ALBERT

Description: Background   Poplars accumulate inordinate amounts of B in their leaves and are candidate plants for the remediation of B contaminated soil. We aimed to determine the effect of heterogeneous B distribution in soil by comparing the growth and B accumulation of young Populus tremula trees growing in soil with heterogeneous and homogeneous B distributions. Methods   The first of two experiments focused on the tolerance and B accumulation of P. tremula under heterogeneous soil B distributions, while the second was designed to study fine root growth under such conditions in detail. Results   Growth and B accumulation of P. tremula were unaffected by the spatial distribution of B. Root and shoot growth were both reduced simultaneously when leaf B concentrations increased above 800 mg kg −1 . In the heterogeneous soil B treatments, root growth was more reduced in spiked soil portions with B concentrations 〉20 mg kg −1 . Fine root length growth was stronger inhibited by B stress than secondary growth. Conclusions   The root growth responses of P. tremula to B are primarily a systemic effect induced by shoot B toxicity and local toxicity effects on roots become dominant only at rather high soil B concentrations. Local heterogeneity in soil B should have little influence on the phytoremediation of contaminated sites. Content Type Journal Article Category Regular Article Pages 1-13 DOI 10.1007/s11104-012-1183-x Authors Rainer Rees, Institute of Terrestrial Ecosystems, ETH Zurich, Universitätstrasse 16, 8092 Zürich, Switzerland Brett H. Robinson, Soil and Physical Sciences, Burns 222, Lincoln University, PO Box 84, Lincoln 7647, Christchurch, New Zealand Michael W. H. Evangelou, Institute of Terrestrial Ecosystems, ETH Zurich, Universitätstrasse 16, 8092 Zürich, Switzerland Eberhard Lehmann, Spallation Neutron Source Division, Paul-Scherrer-Institut, 5232 Villigen PSI, Switzerland Rainer Schulin, Institute of Terrestrial Ecosystems, ETH Zurich, Universitätstrasse 16, 8092 Zürich, Switzerland Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background and Aims   Rainfall is expected to show greater and more variable changes in response to anticipated rising of earth surface temperatures than most other climatic variables, and will be a major driver of ecosystem change. Methods   We studied the effects of predicted changes in California’s rainy season for storage and stabilization mechanisms of soil organic matter (SOM). In a controlled and replicated experiment, we amended rainfall over large plots of natural grassland in accordance with alternative scenarios of future climate change. Results   We found that increases in annual rainfall have important consequences for soil carbon (C) storage, but that the strength and even direction of these effects depend critically on seasonal timing. Additional rainfall during the winter rainy season led to C loss from soil while additions after the typical rainy season increased soil C content. Analysis of MIneral-Organic Matter (OM) associations reveals a potentially powerful mechanism underlying this difference: increased winter rainfall greatly diminished the role of Fe and Al oxides in SOM stabilization. Dithionite extractable crystalline Fe oxides explained more than 35% of the variability in C storage under ambient control and extended spring rainfall conditions, compared to less than 0.01% under increased winter rainfall. Likewise, poorly crystalline Fe and Al oxides explained more than 25 and 40% of the variability in C storage in the control and extended spring rainfall treatments, respectively, but less than 5% in the increased winter rainfall treatment. Conclusions   Increases in annual precipitation identical in amount but at three-month offsets produced opposite effects on soil C storage. Such clear differences in the amount and chemical composition of SOM, and in the vertical distribution of oxides in the soil profile in response to treatment timing carry important implications for the C sequestration trajectory of this ecosystem. Content Type Journal Article Category Regular Article Pages 1-13 DOI 10.1007/s11104-012-1156-0 Authors Asmeret Asefaw Berhe, School of Natural Sciences, University of California, Merced, 4225 N Hospital Rd Castle, Atwater, CA 95301, USA K. Blake Suttle, Grantham Institute for Climate Change & Division of Biology, Imperial College, London, UK Sarah D. Burton, Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, WA, USA Jillian F. Banfield, Department of Earth and Planetary Sciences, University of California, Berkeley, Berkeley, CA, USA Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background and aims   Legumes of the genus Lessertia have recently been introduced to Australia in an attempt to increase the range of forage species available in Australian farming systems capable of dealing with a changing climate. This study assessed the diversity and the nodulation ability of a collection of Lessertia root nodule bacteria isolated from different agro-climatic areas of the Eastern and Western Capes of South Africa. Methods   The diversity and phylogeny of 43 strains was determined via the partial sequencing of the dnaK , 16srRNA and nodA genes. A glasshouse experiment was undertaken to evaluate symbiotic relationships between six Lessertia species and 17 rhizobia strains. Results   The dnaK and 16S rRNA genes of the majority of the strains clustered with the genus Mesorhizobium . The position of the strains at the intra-genus level was incongruent between phylogenies with few exceptions. The nodA genes from Lessertia spp. formed a cluster on their own, separate from the previously known Mesorhizobium nodA sequences. Strains showed differences in their nodulation and nitrogen fixation patterns that could be correlated with nodA gene phylogeny. L. diffusa, L. herbacea and L. excisa nodulated with nearly all the strains examined while L. capitata , L. incana and L. pauciflora were more stringent. Conclusion   Root nodule bacteria from Lessertia spp. were identified mainly as Mesorhizobium spp. Their nodA genes were unique and correlated with the nodulation and nitrogen fixation patterns of the strains. There were marked differences in promiscuity within Lessertia spp. and within strains of root nodule bacteria. Content Type Journal Article Category Regular Article Pages 1-17 DOI 10.1007/s11104-012-1153-3 Authors Macarena Gerding, Facultad de Agronomía, Universidad de Concepción, Chillán, Chile Graham William O’Hara, Centre for Rhizobium Studies, Murdoch University, Perth, Western Australia, Australia Lambert Bräu, Deakin University, School of Life and Environmental Sciences, Burwood, Australia Kemanthie Nandasena, Centre for Rhizobium Studies, Murdoch University, Perth, Western Australia, Australia John Gregory Howieson, Centre for Rhizobium Studies, Murdoch University, Perth, Western Australia, Australia Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background and aims   Replacement of beech by spruce is associated with changes in soil acidity, soil structure and humus form, which are commonly ascribed to the recalcitrance of spruce needles. It is of practical relevance to know how much beech must be admixed to pure spruce stands in order to increase litter decomposition and associated nutrient cycling. We addressed the impact of tree species mixture within forest stands and within litter on mass loss and nutritional release from litter. Methods   Litter decomposition was measured in three adjacent stands of pure spruce ( Picea abies ), mixed beech-spruce and pure beech ( Fagus sylvatica ) on three nutrient-rich sites and three nutrient-poor sites over a three-year period using the litterbag method (single species and mixed species bags). Results   Mass loss of beech litter was not higher than mass loss of spruce litter. Mass loss and nutrient release were not affected by litter mixing. Litter decay indicated non-additive patterns, since similar remaining masses under pure beech (47%) and mixed beech-spruce (48%) were significantly lower than under pure spruce stands (67%). Release of the main components of the organic substance (C org , N tot , P, S, lignin) and associated K were related to mass loss, while release of other nutrients was not related to mass loss. Conclusions   In contradiction to the widely held assumption of slow decomposition of spruce needles, we conclude that accumulation of litter in spruce stands is not caused by recalcitrance of spruce needles to decay; rather adverse environmental conditions in spruce stands retard decomposition. Mixed beech-spruce stands appear to be as effective as pure beech stands in counteracting these adverse conditions. Content Type Journal Article Category Regular Article Pages 1-21 DOI 10.1007/s11104-012-1165-z Authors Torsten W. Berger, Department of Forest- and Soil Sciences, Institute of Forest Ecology, University of Natural Resources and Live Sciences (BOKU), Peter Jordan-Straße 82, 1190 Vienna, Austria Pétra Berger, Department of Forest- and Soil Sciences, Institute of Forest Ecology, University of Natural Resources and Live Sciences (BOKU), Peter Jordan-Straße 82, 1190 Vienna, Austria Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Aims   In the long term absence of catastrophic disturbance ecosystem retrogression occurs, and this is characterized by reduced soil fertility, and impairment of plant biomass and productivity. The response of plant traits to retrogression remains little explored. We investigated how changes plant traits and litter decomposability shift during retrogression for dominant trees and understory shrubs. Methods   We characterized changes in intraspecific, interspecific and community-averaged values of plant traits and litter decomposability, for six abundant species across thirty lake islands in boreal forest that undergo retrogression with increasing time since fire. Results   For understory shrubs, trait values and litter decomposability often changed as soil fertility declined in a manner reflective of greater conservation (versus acquisition) of nutrients, particularly at the interspecific and whole community levels. Such responses were seldom observed for trees, meaning that trees and shrubs show a decoupled response to declining soil fertility during retrogression. Conclusions   Our results only partially agree with previous studies on temperate and subtropical retrogressive chronosequences. Because traits of only shrubs were responsive, they also highlight that impairment of belowground ecosystem processes during retrogression is primarily driven by changes in the trait spectra of understory vegetation rather than that of the trees. Content Type Journal Article Category Regular Article Pages 1-15 DOI 10.1007/s11104-012-1159-x Authors Anna Lagerström, Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, SE-901 83 Umeå, Sweden Marie-Charlotte Nilsson, Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, SE-901 83 Umeå, Sweden David A. Wardle, Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, SE-901 83 Umeå, Sweden Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background and aims   Uptake of 90 Sr and 137 Cs in plants varies widely between soil types and between plant species. It is now recognized that the radionuclide uptake in plants is more influenced by site-specific and plant-specific parameters rather than the bulk radionuclide concentration in soil. We hypothesized that the stress which Alpine plants experience because of the short growing season may enhance the phylogenetic effect on the 137 Cs and 90 Sr transfer factors as well as the dependency of the uptake by plant to the concentrations of exchangeable Ca and K of soils. Methods   We carried out a field study on the 90 Sr and 137 Cs uptake by 11 species of Alpine plants growing on 6 undisturbed and geochemically different soils in the Alpine valley of Piora, Switzerland. Results   Results show that a strong correlation exists between the log TF and the log of exchangeable Ca or K of the soils. Conclusions   Cs uptake by Phleum rhaeticum (Poales) and Alchemilla xanthochlora (Rosales) is more sensitive to the amount of exchangeable K in the soil than the corresponding uptake by other orders. Moreover, the 90 Sr results indicate a phylogenetic effect between Non-Eudicot and Eudicots: the order Poales ( Phleum rhaeticum ) concentrating much less 90 Sr than Eudicots do. Content Type Journal Article Category Regular Article Pages 1-11 DOI 10.1007/s11104-011-1110-6 Authors Thomas Guillaume, Institute for Radiation Physics, University Hospital Center, University of Lausanne, Lausanne, Switzerland Fabienne Chawla, Institute for Radiation Physics, University Hospital Center, University of Lausanne, Lausanne, Switzerland Philipp Steinmann, Federal Office of Public Health, Radiation Protection, Bern, Switzerland Jean-Michel Gobat, Institute of Biology, Laboratory Soil & Vegetation, University of Neuchâtel, Neuchâtel, Switzerland Pascal Froidevaux, Institute for Radiation Physics, University Hospital Center, University of Lausanne, Lausanne, Switzerland Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description:    Diazotrophic species in the genus Herbaspirillum (e.g. H. frisingense , H. rubrisubalbicans and H. seropedicae ) associate with several economically important crops in the family Poaceae, such as maize ( Zea mays ), Miscanthus , rice ( Oryza sativa ), sorghum ( Sorghum bicolor ) and sugarcane ( Saccharum sp.), and can increase their growth and productivity by a number of mechanisms, including nitrogen fixation. Hence, the improvement and use of these plant growth-promoting bacteria could provide economic and environmental benefits. We review the colonization processes of host plants by Herbaspirillum spp., including histological aspects and molecular mechanisms involved in these interactions, which may be epiphytic, endophytic, and even occasionally pathogenic. Herbaspirillum can recognize plant signals that modulate the expression of colonization traits and plant growth-promoting factors. Although a large proportion of herbaspirilla remain rhizospheric and epiphytic, plant-associated species in this genus are noted for their ability to colonize the plant internal tissues. Endophytic colonization by herbaspirilla begins with the attachment of the bacteria to root surfaces, followed by colonization at the emergence points of lateral roots and penetration through discontinuities of the epidermis; this appears to involve bacterial envelope structures, such as lipopolysaccharide (LPS), exopolysaccharide (EPS), adhesins and the type three secretion system (T3SS), but not necessarily the involvement of cell wall-degrading enzymes. Intercellular spaces are then rapidly occupied, proceeding to colonization of xylem and the aerial parts of the host plants. The response of the host plant includes both the recognition of the bacteria as non-pathogenic and the induction of systemic resistance to pathogens. Phytohormone signaling cascades are also activated, regulating the plant development. This complex molecular communication between some Herbaspirillum spp. and plant hosts can result in plant growth-promotion. Content Type Journal Article Category Review Article Pages 1-22 DOI 10.1007/s11104-012-1125-7 Authors Rose Adele Monteiro, Department of Biochemistry and Molecular Biology, Universidade Federal do Paraná, Curitiba, PR, Brazil Eduardo Balsanelli, Department of Biochemistry and Molecular Biology, Universidade Federal do Paraná, Curitiba, PR, Brazil Roseli Wassem, Department of Genetics, Universidade Federal do Paraná, Curitiba, PR, Brazil Anelis M. Marin, Department of Biochemistry and Molecular Biology, Universidade Federal do Paraná, Curitiba, PR, Brazil Liziane C. C. Brusamarello-Santos, Department of Biochemistry and Molecular Biology, Universidade Federal do Paraná, Curitiba, PR, Brazil Maria Augusta Schmidt, Department of Biochemistry and Molecular Biology, Universidade Federal do Paraná, Curitiba, PR, Brazil Michelle Z. Tadra-Sfeir, Department of Biochemistry and Molecular Biology, Universidade Federal do Paraná, Curitiba, PR, Brazil Vânia C. S. Pankievicz, Department of Biochemistry and Molecular Biology, Universidade Federal do Paraná, Curitiba, PR, Brazil Leonardo M. Cruz, Department of Biochemistry and Molecular Biology, Universidade Federal do Paraná, Curitiba, PR, Brazil Leda S. Chubatsu, Department of Biochemistry and Molecular Biology, Universidade Federal do Paraná, Curitiba, PR, Brazil Fabio O. Pedrosa, Department of Biochemistry and Molecular Biology, Universidade Federal do Paraná, Curitiba, PR, Brazil Emanuel M. Souza, Department of Biochemistry and Molecular Biology, Universidade Federal do Paraná, Curitiba, PR, Brazil Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background & aims   Plants may have dissimilar effects on ecosystem processes because they possess different attributes. Given increasing biodiversity losses, it is important to understand which plant traits are key drivers of ecosystem functions. To address this question, we studied the response of two ecosystem functions that remove nitrogen (N) from wetland soils, the accumulation of N in plant biomass and denitrification potential (DNP), to variation in plant trait composition. Methods   Our experiment manipulated plant composition in a riparian wetland. We determined relative importance of plant traits and environmental variables as predictors of each ecosystem function. Results   We demonstrate that Water Use Efficiency (WUE) had a strong negative effect on biomass N. Root porosity and belowground biomass were negatively correlated with DNP. Trait ordination indicated that WUE was largely orthogonal to traits that maximized DNP. Conclusions   These results indicate that plant species with different trait values are required to maintain multiple ecosystem functions, and provide a more mechanistic, trait-based link between the recent findings that higher biodiversity is necessary for multi-functionality. While we selected plant traits based on ecological theory, several of the plant traits were not good predictors of each ecosystem function suggesting the ecological theory linking traits to function is incomplete and requires strengthening. Content Type Journal Article Category Regular Article Pages 1-17 DOI 10.1007/s11104-011-1113-3 Authors A. E. Sutton-Grier, Nicholas School of the Environment and Earth Sciences, Duke University, Box 90328, Durham, NC, USA J. P. Wright, Biology Department, Duke University, Box 90338, Durham, NC, USA C. J. Richardson, Nicholas School of the Environment and Earth Sciences, Duke University, Box 90333, Durham, NC, USA Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Aims   The aim of this study was to compare the residual effects in soil and the influence on a flax crop ( Linum usitatissimum L.) of applying Zn from different commercial synthetic chelates. The chelates used were: Zn-EDDHSA (Zn-ethylenediamine-N,N'-bis(2-hydroxyphenylacetate), Zn-EDTA (Zn-ethylenediaminetetraacetate), Zn-HEDTA (Zn-N-2-hydroxyethyl-ethylenediaminetriacetate), Zn-EDTA-HEDTA and Zn-DTPA-HEDTA-EDTA (Zn-DTPA, Zn-diethylenetriaminepentaacetate). Methods   The experiment was conducted in a greenhouse using two different soils (Soil acid : a weakly acidic soil and Soil calc : a calcareous soil). Each treatment was administered, in a single application, to a previous flax crop at different Zn application rates. The yield and some of the flax crop quality parameters were determined in the present flax crop. Soil Zn behavior was then evaluated by single and sequential extraction. Results   In Soil acid , the Zn-HEDTA and Zn-EDDHSA fertilizers produced the highest plant parameters values (total Zn concentration, total uptake Zn), percentages of Zn utilization and values of the transfer factor, TF. In contrast, in Soil calc these fertilizers produced the lowest in-plant values, with this soil producing the highest yield, quality, percentage of utilization and TF associated with the application of Zn-DTPA-HEDTA-EDTA and Zn-EDTA fertilizers. However, the Zn-EDTA in Soil acid and Zn-DTPA-HEDTA-EDTA in Soil calc , were associated with the greatest amounts of bioavailable Zn in soil and also with the highest Zn concentrations associated with the sum of the most labile fractions (water soluble plus exchangeable fractions). Conclusions   The residual Zn produced by the different fertilizer treatments estimated using the DTPA, Mehlich-3- and LMWOAs methods- was available in sufficient quantities that it not be necessary to add any further Zn (which could have resulted in over-fertilization) for the subsequent crop to either of the soils. Content Type Journal Article Category Regular Article Pages 1-15 DOI 10.1007/s11104-012-1502-2 Authors Patricia Almendros, Chemistry and Agricultural Analysis Department, College of Agriculture, Technical University of Madrid (UPM), Ciudad Universitaria s.n., 28040 Madrid, Spain Demetrio Gonzalez, Chemistry and Agricultural Analysis Department, College of Agriculture, Technical University of Madrid (UPM), Ciudad Universitaria s.n., 28040 Madrid, Spain Jose M. Alvarez, Chemistry and Agricultural Analysis Department, College of Agriculture, Technical University of Madrid (UPM), Ciudad Universitaria s.n., 28040 Madrid, Spain Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Can hydraulic traits be used to predict sensitivity of drought-prone forests to crown decline and tree mortality? Content Type Journal Article Category Commentary Pages 1-3 DOI 10.1007/s11104-012-1508-9 Authors Rafael S. Oliveira, Departamento de Biologia Vegetal, Instituto de Biologia, Universidade Estadual de Campinas, Campinas, 13083-862 SP, Brazil Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background and aims   In post mining landscapes as in the Lusatian region (Brandenburg, Germany), Pleistocene coarse-textured, sandy sediments are used for soil rehabilitation and land reclamation. The homogeneously-appearing initial soils are characterized by finer-textured soil clumps (fragments) of different sizes that are embedded in a sandy matrix. These soils with typical local-scale heterogeneity may serve as a model for studying how spatially-distributed soil fragments may be utilized by pioneering plant species. The aim of this study was to gain insight into the physical and chemical properties of sandy matrix and fragments that could possibly explain why embedded fragment may act as hot spots for root growth. Methods   In 2009, three soil monoliths of dimension 50 cm × 50 cm × 50 cm that were exclusively vegetated by Lotus corniculatus L. planted in 2008 were studied. Each layer of 10 cm was sampled successively using a cubic metal frame with 10 cm edge length (25 samples per layer each with a volume of 1 l). The samples were analyzed for root biomass, root lengths and diameter, and for chemical and physical properties of sandy matrix and fragments. Results   Bulk density, water contents, total carbon, total nitrogen, and plant available calcium contents were higher for the fragments compared to the sandy matrix. The roots of L. corniculatus were heterogeneously distributed in the monoliths. The root density distributions for the 1 L samples indicated a positive influence of fragments on directed root growth. Fragments embedded in the sandy matrix were found to be strongly penetrated by roots despite their relatively high bulk density. The presence of fragments also led to an increased root biomass in the sandy matrix in the direct vicinity of fragments. Such direct effects on root development were accompanied by more indirect effects by locally-elevated moisture and nutrient contents. Conclusion   The results suggest that finer-textured fragments embedded in coarser-textured sediments, can have favorable effect on plant and root development during the initial stages of establishment of vegetation cover. The fragments can act as water and nutrient hot spots to improve supply of pioneering plants especially in coarse-textured soil. The existence of small-scale heterogeneities owing to incomplete sediment mixing e.g., in soil reclamation, could be generally important for controlling the speed and direction of early plants-establishment, for instance, in the succession of post-mining areas. Content Type Journal Article Category Regular Article Pages 1-16 DOI 10.1007/s11104-012-1505-z Authors Katja M. Boldt-Burisch, Soil Protection and Recultivation, Brandenburg University of Technology, 03046 Cottbus, Germany Horst H. Gerke, Institute of Soil Landscape Research, Leibniz-Centre for Agricultural Landscape Research (ZALF), Müncheberg, Eberswalder Straße 84, 15374 Müncheberg, Germany Seth Nii-Annang, Soil Protection and Recultivation, Brandenburg University of Technology, 03046 Cottbus, Germany Bernd Uwe Schneider, Helmholtz Centre Potsdam – German Research Centre for Geosciences, Telegrafenberg, 14473 Potsdam, Germany Reinhard F. Hüttl, Soil Protection and Recultivation, Brandenburg University of Technology, 03046 Cottbus, Germany Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Aims   Potatoes have an inadequate rooting system for efficient acquisition of water and minerals and use disproportionate amounts of irrigation and fertilizer. This research determines whether significant variation in rooting characteristics of potato exists, which characters correlate with final yield and whether a simple screen for rooting traits could be developed. Methods   Twenty-eight genotypes of Solanum tuberosum groups Tuberosum and Phureja were grown in the field; eight replicate blocks to final harvest, while entire root systems were excavated from four blocks. Root classes were categorised and measured. The same measurements were made on these genotypes in the glasshouse, 2 weeks post emergence. Results   In the field, total root length varied from 40 m to 112 m per plant. Final yield was correlated negatively with basal root specific root length and weakly but positively with total root weight. Solanum tuberosum group Phureja genotypes had more numerous roots and proportionally more basal than stolon roots compared with Solanum tuberosum , group Tuberosum genotypes. There were significant correlations between glasshouse and field measurements. Conclusions   Our data demonstrate that variability in rooting traits amongst commercially available potato genotypes exists and a robust glasshouse screen has been developed. By measuring potato roots as described in this study, it is now possible to assess rooting traits of large populations of potato genotypes. Content Type Journal Article Category Regular Article Pages 1-19 DOI 10.1007/s11104-012-1483-1 Authors Jane Wishart, School of Biology, University of St Andrews, St Andrews, Fife KY16 9TS, UK Timothy S. George, The James Hutton Institute, Invergowrie, Dundee DD2 5DA, UK Lawrie K. Brown, The James Hutton Institute, Invergowrie, Dundee DD2 5DA, UK Gavin Ramsay, The James Hutton Institute, Invergowrie, Dundee DD2 5DA, UK John E. Bradshaw, The James Hutton Institute, Invergowrie, Dundee DD2 5DA, UK Philip J. White, The James Hutton Institute, Invergowrie, Dundee DD2 5DA, UK Peter J. Gregory, East Malling Research, New Road, East Malling ME19 6BJ, UK Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background and Aims   This study was conducted to reveal the genetic diversity of common bean ( Phaseolus vulgaris L.) nodulating rhizobia in various agroecological regions in Nepal. Method   A total of 63 strains were isolated from common bean grown in the soils collected from seven bean fields in Nepal and characterized based on the partial sequences of 16S–23S internal transcribed spacer (ITS) regions, 16S rDNA, nodC , and nifH . Symbiotic properties of some representative strains with host plants were examined to elucidate their characteristics in relation to genotype and their origin. Results   The isolated strains belonged to Rhizobium leguminosarum , Rhizobium etli , Rhizobium phaseoli , and one unknown Rhizobium lineage, all belonging to a common symbiovar (sv.) phaseoli . Nine ITS genotypes were detected mainly corresponding to a single site, including a dominant group at three sites harboring highly diverse multiple ITS sequences. Three symbiotic genotypes corresponded to a geographical region, not to the ribosomal DNA group, suggesting horizontal transfer of symbiotic genes separately in each region. Great differences in nitrogenase activity and nodule forming ability among the strains irrespective of their species and origin were observed. Conclusions   Nepalese Himalaya harbor phylogenetically highly diverse and site-specific strains of common bean rhizobia, some of which could have high potential of symbiotic nitrogen fixation. Content Type Journal Article Category Regular Article Pages 1-13 DOI 10.1007/s11104-012-1518-7 Authors Dinesh Adhikari, Faculty of Life and Environmental Science, Shimane University, 1060 Nishikawatsu, Matsue, Shimane 690-8504, Japan Kazuhito Itoh, Faculty of Life and Environmental Science, Shimane University, 1060 Nishikawatsu, Matsue, Shimane 690-8504, Japan Kousuke Suyama, Faculty of Life and Environmental Science, Shimane University, 1060 Nishikawatsu, Matsue, Shimane 690-8504, Japan Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background and aims   Replant problems or soil sickness are known phenomena but still unsolved. The aims of this study were (i) to set up a test system for detecting replant problems using in vitro propagated apple rootstocks (M26) based on different soil disinfection treatments and (ii) to explore the treatment effects on root morphology and soil microbial community structure. Methods   The bio-test involved soil with apple replant problems (apple sick) and healthy soil from an adjacent plot, both either untreated, or submitted to treatments of 50 and 100 °C, or the chemical soil disinfectant Basamid. Histological analyses of roots and denaturing gradient gel electrophoresis (DGGE) fingerprints in rhizosphere soil collected at the final evaluation were performed. Results   After 10 weeks, shoot dry mass on apple sick soil was 79, 108 and 124 % higher for soil treated at 50 °C, 100 °C and with Basamid, respectively, compared to the untreated soil. Roots in untreated apple sick soil showed destroyed epidermal and cortical layers. DGGE fingerprints revealed treatment dependent differences in community composition and relative abundance of total bacteria, Bacillus , Pseudomonas and total fungi. Conclusions   The clear differences detected in soil microbial communities are the first steps towards a better understanding of the causes for apple replant problems. Content Type Journal Article Category Regular Article Pages 1-15 DOI 10.1007/s11104-012-1454-6 Authors Bunlong Yim, Leibniz Universität Hannover—Institute of Floriculture and Woody Plant Science, Tree Nursery Science Section, Herrenhäuser Str. 2, 30419 Hannover, Germany Kornelia Smalla, Julius Kühn-Institut, Institute for Epidemiology and Pathogen Diagnostics, Messeweg 11-12, 38104 Braunschweig, Germany Traud Winkelmann, Leibniz Universität Hannover—Institute of Floriculture and Woody Plant Science, Tree Nursery Science Section, Herrenhäuser Str. 2, 30419 Hannover, Germany Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background and aims   Root decomposition studies have rarely considered the heterogeneity within a fine-root system. Here, we investigated fine root (〈 0.5 and 0.5–2 mm in diameter) decomposition and accompanying nutrient dynamics of two temperate tree species— Betula costata Trautv and Pinus koraiensis Sieb. et Zucc. Methods   Both litterbag and intact-core techniques were used to examine decomposition dynamic and nutrient release of the two size class roots over a 498-day period. Moreover, we examined differences between the two approaches. Results   The very fine roots (〈 0.5 mm) with an initially lower C:N ratio, decomposed more slowly than 0.5–2 mm roots of both tree species. The differences in mass loss between size classes were smaller when using the intact-core technique compared with litterbag technique. In contrast to root biomass loss, net N release was much higher in the fine roots (〈 0.5 mm). All fine roots initially released N (0–75 days), but immobilized N to varying extent in the following days (75–498 days) during decomposition. Conclusions   Our results suggest that the slow decomposition rate of very fine roots (〈 0.5 mm) may be determined by their high concentration of acid-unhydrolyzable structural components. Additionally, the heterogeneity within a bulk fine-root system could lead to differences in their contribution to soil in terms of carbon and nitrogen dynamics. Content Type Journal Article Category Regular Article Pages 1-14 DOI 10.1007/s11104-012-1457-3 Authors Tao Sun, Key Laboratory of Forest Plant Ecology, Ministry of Education, Northeast Forestry University, Harbin, 150040 People’s Republic of China Zijun Mao, Key Laboratory of Forest Plant Ecology, Ministry of Education, Northeast Forestry University, Harbin, 150040 People’s Republic of China Lili Dong, Key Laboratory of Forest Plant Ecology, Ministry of Education, Northeast Forestry University, Harbin, 150040 People’s Republic of China Lingling Hou, Key Laboratory of Forest Plant Ecology, Ministry of Education, Northeast Forestry University, Harbin, 150040 People’s Republic of China Yuan Song, Key Laboratory of Forest Plant Ecology, Ministry of Education, Northeast Forestry University, Harbin, 150040 People’s Republic of China Xiuwei Wang, School of Forestry, Northeast Forestry University, Harbin, 150040 People’s Republic of China Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background and Aims   Several strains of rhizobacteria may be found in the rhizospheric soil, on the root surface or in association with rice plants. These bacteria are able to colonize plant root systems and promote plant growth and crop yield through a variety of mechanisms. The objectives of this study were to isolate, identify, and characterize putative plant growth-promoting rhizobacteria (PGPR) associated with rice cropped in different areas of southern Brazil. Methods   Bacterial strains were selectively isolated based on their growth on three selective semi-solid nitrogen-free media. Bacteria were identified at the genus level by PCR-RFLP 16S rRNA gene analysis and partial sequencing methodologies. Bacterial isolates were evaluated for their ability to produce indolic compounds and siderophores and to solubilize phosphate. In vitro biological nitrogen fixation and the ability to produce 1-aminocyclopropane-1-carboxylate deaminase were evaluated for each bacterial isolate used in the inoculation experiments. Results   In total, 336 bacterial strains were isolated representing 31 different bacterial genera. Strains belonging to the genera Agrobacterium, Burkholderia, Enterobacter, and Pseudomonas were the most prominent isolates. Siderophore and indolic compounds producers were widely found among isolates, but 101 isolates were able to solubilize phosphate. Under gnotobiotic conditions, eight isolates were able to stimulate the growth of rice plants. Five of these eight isolates were also field tested in rice plants subjected to different nitrogen fertilization rates. Conclusions   The results showed that the condition of half-fertilization plus separate inoculation with the isolates AC32 ( Herbaspirillum sp.), AG15 ( Burkholderia sp.), CA21 ( Pseudacidovorax sp.), and UR51 ( Azospirillum sp.) achieved rice growth similar to those achieved by full-fertilization without inoculation, thus highlighting the potential of these strains for formulating new bioinoculants for rice crops. Content Type Journal Article Category Regular Article Pages 1-19 DOI 10.1007/s11104-012-1430-1 Authors Rocheli de Souza, Departamento de Genética, Instituto de Biociências, Universidade Federal do Rio Grande do Sul (UFRGS), Av. Bento Gonçalves, 9500, Caixa Postal 15.053, Prédio 43312, sala 207b, Porto Alegre, RS CEP 91501-970, Brasil Anelise Beneduzi, Fundação Estadual de Pesquisa Agropecuária (FEPAGRO), Rua Gonçalves Dias 570, 90130-060 Porto Alegre, RS, Brasil Adriana Ambrosini, Departamento de Genética, Instituto de Biociências, Universidade Federal do Rio Grande do Sul (UFRGS), Av. Bento Gonçalves, 9500, Caixa Postal 15.053, Prédio 43312, sala 207b, Porto Alegre, RS CEP 91501-970, Brasil Pedro Beschoren da Costa, Departamento de Genética, Instituto de Biociências, Universidade Federal do Rio Grande do Sul (UFRGS), Av. Bento Gonçalves, 9500, Caixa Postal 15.053, Prédio 43312, sala 207b, Porto Alegre, RS CEP 91501-970, Brasil Jacqueline Meyer, Departamento de Genética, Instituto de Biociências, Universidade Federal do Rio Grande do Sul (UFRGS), Av. Bento Gonçalves, 9500, Caixa Postal 15.053, Prédio 43312, sala 207b, Porto Alegre, RS CEP 91501-970, Brasil Luciano K. Vargas, Fundação Estadual de Pesquisa Agropecuária (FEPAGRO), Rua Gonçalves Dias 570, 90130-060 Porto Alegre, RS, Brasil Rodrigo Schoenfeld, Instituto Riograndense do Arroz (IRGA), Avenida Bonifácio Carvalho Bernardes 1494, 94930-030 Cachoeirinha, RS, Brasil Luciane M. P. Passaglia, Departamento de Genética, Instituto de Biociências, Universidade Federal do Rio Grande do Sul (UFRGS), Av. Bento Gonçalves, 9500, Caixa Postal 15.053, Prédio 43312, sala 207b, Porto Alegre, RS CEP 91501-970, Brasil Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Aims   This study explored molecular mechanism of ascorbic acid (AsA)-mediated enhancement of plant tolerance against cadmium (Cd) stress. Methods   Complex pharmacological, histochemical and molecular approaches were applied to analyse the effect of AsA on the alleviation of Cd stress and corresponding signalling pathway. Results   Cd stress brought about severe oxidative damage and remarkable decrease in AsA content in alfalfa (Medicago sativa) seedling roots. Exogenous AsA not only increased AsA content in vivo, and strengthened the up-regulation of alfalfa heme oxygenase-1 (HO-1) transcript and HO activity triggered by Cd, but also significantly decreased Cd accumulation and oxidative damage, which was confirmed by the histochemical analysis. The responses of AsA were further impaired by the potent inhibitor of HO-1, zinc protoporphyrin IX (ZnPP), which were blocked further when 50 % saturation of carbon monoxide (CO) aqueous solution (in particular) or bilirubin (BR), two catalytic by-products of HO-1, was added, respectively. Molecular evidence illustrated that AsA-triggered the up-regulation of antioxidant enzyme genes, especially Mn-SOD and POD , were sensitive to ZnPP and reversed by CO. Conclusions   In short, above results suggested that cytoprotective roles triggered by AsA might be, at least partially, through HO-1-dependent fashion by the induction of antioxidant system and lowering Cd accumulation. Content Type Journal Article Category Regular Article Pages 1-12 DOI 10.1007/s11104-012-1451-9 Authors Qijiang Jin, College of Life Sciences, Co. Laboratory of Nanjing Agricultural University and Carl Zeiss Far East, Jiangsu Province, Nanjing Agricultural University, Nanjing, 210095 People,s Republic of China Kaikai Zhu, College of Life Sciences, Co. Laboratory of Nanjing Agricultural University and Carl Zeiss Far East, Jiangsu Province, Nanjing Agricultural University, Nanjing, 210095 People,s Republic of China Yanjie Xie, College of Life Sciences, Co. Laboratory of Nanjing Agricultural University and Carl Zeiss Far East, Jiangsu Province, Nanjing Agricultural University, Nanjing, 210095 People,s Republic of China Wenbiao Shen, College of Life Sciences, Co. Laboratory of Nanjing Agricultural University and Carl Zeiss Far East, Jiangsu Province, Nanjing Agricultural University, Nanjing, 210095 People,s Republic of China Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background and aims   The beneficial effects of Si have mainly been observed in herbaceous plants, while little is known about its role in deciduous trees. The aim of this work was to evaluate the effect of foliar application of Si on chestnut leaf growth, photosynthesis and water relations in the presence of short, but intense water deficit. Methods   Sili-K® solution (containing 0.12 % Si and 0.15 % K) was repeatedly (× 3) sprayed onto leaves of potted chestnut plantlets and irrigation was suspended 7 weeks later, for 8 days. Leaf growth, anatomy, as well as physiological and biochemical traits of the plantlets were studied. Results   Si application enhanced chestnut growth, due to increased photosynthetic traits, including higher chlorophyll content and chlorophyll a to b ratio, photochemical efficiency of PSII, gas exchange (stomatal conductance, transpiration rate, net CO 2 assimilation) and oxygen evolution rate. Meanwhile, Si yielded larger and thinner leaves, higher xylem, specific leaf area and transpiration rate, thus being beneficial to the tree in absorbing sunlight energy for photosynthesis and in alleviating heat stress. However, Si also lowered leaf sap osmotic pressure, causing the plant to lose water more quickly, thus being more susceptible to water stress. Conclusions   Si improved chestnut photosynthesis, growth, and heat stress tolerance, but it also increased the susceptibility to drought. Content Type Journal Article Category Regular Article Pages 1-15 DOI 10.1007/s11104-012-1385-2 Authors Changhe Zhang, Centre for the Research and Technology of Agro-Environmental and Biological Sciences (CITAB)/Department of Biological and Environmental Engineering (DeBA), Universidade de Trás-os-Montes e Alto Douro, Apt. 1013, 5001-801 Vila Real, Portugal José M. Moutinho-Pereira, Centre for the Research and Technology of Agro-Environmental and Biological Sciences (CITAB)/Department of Biological and Environmental Engineering (DeBA), Universidade de Trás-os-Montes e Alto Douro, Apt. 1013, 5001-801 Vila Real, Portugal Carlos Correia, Centre for the Research and Technology of Agro-Environmental and Biological Sciences (CITAB)/Department of Biological and Environmental Engineering (DeBA), Universidade de Trás-os-Montes e Alto Douro, Apt. 1013, 5001-801 Vila Real, Portugal João Coutinho, Centre of Chemistry (CQ)/Department of Soil Science, Universidade de Trás-os-Montes e Alto Douro, Apt. 1013, 5001-801 Vila Real, Portugal António Gonçalves, Centre for the Research and Technology of Agro-Environmental and Biological Sciences (CITAB)/Department of Biological and Environmental Engineering (DeBA), Universidade de Trás-os-Montes e Alto Douro, Apt. 1013, 5001-801 Vila Real, Portugal Américo Guedes, Centre for the Research and Technology of Agro-Environmental and Biological Sciences (CITAB)/Department of Biological and Environmental Engineering (DeBA), Universidade de Trás-os-Montes e Alto Douro, Apt. 1013, 5001-801 Vila Real, Portugal José Gomes-Laranjo, Centre for the Research and Technology of Agro-Environmental and Biological Sciences (CITAB)/Department of Biological and Environmental Engineering (DeBA), Universidade de Trás-os-Montes e Alto Douro, Apt. 1013, 5001-801 Vila Real, Portugal Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Aims   Aluminum-tolerant wheat plants often produce more root exudates such as malate and phosphate than aluminum-sensitive ones under aluminum (Al) stress, which provides environmental differences for microorganism growth in their rhizosphere soils. This study investigated whether soil bacterial community composition and abundance can be affected by wheat plants with different Al tolerance. Methods   Two wheat varieties, Atlas 66 (Al-tolerant) and Scout 66 (Al-sensitive), were grown for 60 days in acidic soils amended with or without CaCO 3 . Plant growth, soil pH, exchangeable Al content, bacterial community composition and abundance were investigated. Results   Atlas 66 showed better growth and lower rhizosphere soil pH than Scout 66 irrespective of CaCO 3 amendment or not, while there was no significant difference in the exchangeable Al content of rhizosphere soil between the two wheat lines. The dominant bacterial community composition and abundance in rhizosphere soils did not differ between Atlas 66 and Scout 66, although the bacterial abundance in rhizosphere soil of both wheat lines was significantly higher than that in bulk soil. Sphingobacteriales , Clostridiales , Burkholderiales and Acidobacteriales were the dominant bacteria phylotypes. Conclusions   The difference in wheat Al tolerance does not induce the changes in the dominant bacterial community composition or abundance in the rhizosphere soils. Content Type Journal Article Category Regular Article Pages 1-10 DOI 10.1007/s11104-012-1473-3 Authors Chao Wang, State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008 China Xue Qiang Zhao, State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008 China Rong Fu Chen, State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008 China Hai Yan Chu, State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008 China Ren Fang Shen, State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008 China Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background and aims   The aim of this study is to enhance our knowledge of nitrogen (N) cycling and N acquisition in tropical montane forests through analysis of stable N isotopes (δ 15 N). Methods   Leaves from eight common tree species, leaf litter, soils from three depths and roots were sampled from two contrasting montane forest types in Jamaica (mull ridge and mor ridge) and were analysed for δ 15 N. Results   All foliar δ 15 N values were negative and varied among the tree species but were significantly more negative in the mor ridge forest (by about 2 ‰). δ 15 N of soils and roots were also more negative in mor ridge forests by about 3 ‰. Foliar δ 15 N values were closer to that of soil ammonium than soil nitrate suggesting that trees in these forests may have a preference for ammonium; this may explain the high losses of nitrate from similar tropical montane forests. There was no correlation between the rankings of foliar δ 15 N in the two forest types suggesting a changing uptake ratio of different N forms between forest types. Conclusions   These results indicate that N is found at low concentrations in this ecosystem and that there is a tighter N cycle in the mor ridge forest, confirmed by reduced nitrogen availability and lower rates of nitrification. Overall, soil or root δ 15 N values are more useful in assessing ecosystem N cycling patterns as different tree species showed differences in foliar δ 15 N between the two forest types. Content Type Journal Article Category Regular Article Pages 1-12 DOI 10.1007/s11104-012-1469-z Authors Francis Q. Brearley, Department of Botany, Trinity College, University of Dublin, Dublin 2, Ireland Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Aims   Explore how soil CO 2 efflux and its components change after moving sand dunes are stabilized with shrubs, and how abiotic factors affect those components at different scales. Methods   Soil CO 2 efflux from a sand-stabilized area was compared to that from moving sand dunes in the Tengger Desert. To partition rhizosphere respiration (R R ) from soil basal respiration (R B ), a root-isolation plot was established. Results   Compared to moving sand dunes, total soil respiration (R T ) in the sand-stabilized area increased 3.2 fold to 0.28 ± 0.08 μmol CO 2 m -2  s -1 , two thirds of which was from R B . Shrub patchiness produced spatial variation in soil respiration, whereas temporal dynamics of soil respiration were affected mainly by soil water content. Shallow soil water content (0–20 cm) influenced R T and R B , whereas deep soil water content (30–210 cm) influenced R R and the ratio R R /R T . During most of the year when soil water content was below field capacity, diurnal changes in soil respiration were partially decoupled from soil temperature but could be modeled using soil temperature and photosynthetic active radiation. Conclusions   Sand-dune stabilization increased soil respiration, and increased R B from biological soil crust and altered soil properties such as increased soil organic matter contributed more than increased R R from increased shrubs. Content Type Journal Article Category Regular Article Pages 1-15 DOI 10.1007/s11104-012-1465-3 Authors Zhi-Shan Zhang, Shapotou Desert Research and Experimental Station, Cold and Arid Region Environmental and Engineering Research Institute, Chinese Academy of Sciences, Donggang West Road 320, Lanzhou, 730000 People’s Republic of China Xin-Rong Li, Shapotou Desert Research and Experimental Station, Cold and Arid Region Environmental and Engineering Research Institute, Chinese Academy of Sciences, Donggang West Road 320, Lanzhou, 730000 People’s Republic of China Robert S. Nowak, Department of Natural Resources and Environmental Science, Mail Stop 186, University of Nevada Reno, Reno, NV 89557, USA Pan Wu, Shapotou Desert Research and Experimental Station, Cold and Arid Region Environmental and Engineering Research Institute, Chinese Academy of Sciences, Donggang West Road 320, Lanzhou, 730000 People’s Republic of China Yan-Hong Gao, Shapotou Desert Research and Experimental Station, Cold and Arid Region Environmental and Engineering Research Institute, Chinese Academy of Sciences, Donggang West Road 320, Lanzhou, 730000 People’s Republic of China Yang Zhao, Shapotou Desert Research and Experimental Station, Cold and Arid Region Environmental and Engineering Research Institute, Chinese Academy of Sciences, Donggang West Road 320, Lanzhou, 730000 People’s Republic of China Lei Huang, Shapotou Desert Research and Experimental Station, Cold and Arid Region Environmental and Engineering Research Institute, Chinese Academy of Sciences, Donggang West Road 320, Lanzhou, 730000 People’s Republic of China Yi-Gang Hu, Shapotou Desert Research and Experimental Station, Cold and Arid Region Environmental and Engineering Research Institute, Chinese Academy of Sciences, Donggang West Road 320, Lanzhou, 730000 People’s Republic of China Rong-Liang Jia, Shapotou Desert Research and Experimental Station, Cold and Arid Region Environmental and Engineering Research Institute, Chinese Academy of Sciences, Donggang West Road 320, Lanzhou, 730000 People’s Republic of China Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background   Magnesium (Mg), as an essential mineral element for plants and microbes, can have both indirect as well as direct effects on disease. Balanced nutrition is critical for the expression of disease resistance since nutrition is part of a delicately balanced interdependent system influenced by the plant’s genetics and the environment. A deficiency or excess of Mg can influence a wide range of physiologic functions because of these interrelated processes. Scope   There are fewer reports of direct effects of Mg deficiency or excess on plant disease than for many elements because of its participation in a wide spectrum of general physiological functions so that individual activities involved in defense, virulence, or pathogenesis are not as easily characterized. The ability of Mg to compliment or antagonize other minerals can result in different disease responses to Mg under varying environmental conditions. Fusarium wilt pathogens tend to be less severe when adequate Mg is available, and Mg increases resistance of tissues to degradation by some pectolytic enzymes of macerating or soft rotting pathogens. In contrast, high rates of Mg that interfere with Ca uptake may increase the incidence of diseases such as bacterial spot of tomato and pepper or peanut pod rot. Conclusions   The more general physiological benefits of Mg for active growth often obscure specific mechanisms involved in resistance to disease, although Mg is an important contributor to over-all plant health. A specific mechanism of defense to diseases enhanced by Mg includes increased resistance of tissues to degradation by pectolytic enzymes of bacterial soft rotting pathogens. Management of Mg nutrition to reduce disease, in balance with other minerals, is an underutilized tool for disease control. Content Type Journal Article Category Regular Article Pages 1-13 DOI 10.1007/s11104-012-1476-0 Authors Don M. Huber, Purdue University, West Lafayette, IN, USA Jeff B. Jones, University of Florida, IFAS, Gainesville, FL, USA Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background and aims   Soil carbon storage is an important component of global carbon cycling. Andean Andisols have high carbon content and are vulnerable to erosion because of agricultural intensification and deforestation. This study examines the effects of land use on erosion and soil carbon storage in the Río Chimbo watershed of Ecuador. Methods   Soil carbon content, age, and erosion estimated from 137 Cs inventories was measured along an elevational transect under annual cropping, natural forest, páramo, pasture, and tree plantations. Results   Land use, particularly annual cropping, affected 137 Cs levels in the upper soil layers, but did not have an impact on total carbon storage to a depth of 1 m. Relative erosion rates estimated from 137 Cs inventories at sites under annual cropping averaged 27 t ha −1  y −1 over the erosion rate of non-cultivated sites. A linear relationship was observed between soil carbon age (determined by 14 C levels) and 137 Cs levels, where pasture sites had lower 137 Cs and older carbon compared to natural forest sites. Conclusions   The effects of land use on soil loss in the Río Chimbo watershed suggest a loss and/or removal of soil carbon, particularly under annual cropping. Content Type Journal Article Category Regular Article Pages 1-15 DOI 10.1007/s11104-012-1478-y Authors A. Henry, Intercollege Program in Plant Biology, The Pennsylvania State University, University Park, PA 16802, USA L. Mabit, Environmental Geosciences, Department of Environmental Sciences, University of Basel, Basel, Switzerland R. E. Jaramillo, Department of Plant Science, The Pennsylvania State University, University Park, PA 16802, USA Y. Cartagena, Instituto Nacional Autónomo de Investigaciones Agropecuarias, Estación Experimental Santa Catalina, Quito, Ecuador J. P. Lynch, Intercollege Program in Plant Biology, The Pennsylvania State University, University Park, PA 16802, USA Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Aims   Effects of final harvest of plantations and re-conversion with different tillage intensities on quantity and distribution of organic matter in different soil fractions were assessed. Methods   A field trial was conducted at two poplar and one willow plantation in northern Germany. Distribution of C in aboveground plant and root biomass and within various soil fractions (particulate organic matter, water-stable aggregates, microbial biomass) was determined. Directly after re-conversion, which was performed at tillage depths of 5, 15 and 30 cm, C amounts added with coarse harvest residues and changes in soil C fractions were examined. Results   Plantation C stocks decreased in the order soil 〉 aboveground biomass 〉 roots. After re-conversation no change in bulk soil SOC but an increase of labile soil C was observed. Between 16 and 30 t ha −1 additional C was determined in the soil fraction of plant residues 〉2 mm after re-conversion. Up to 90 % SOC of the fine earth fraction was associated with macroaggregates, which increased after re-conversion despite intensive tillage with a rotary cultivator. Conclusion   The duration of the increased macroaggregate associated C directly after soil tillage is a short term effect of the tillage. The influence of tillage depths on soil C-fractions could be observed only in some cases because of the high variability of harvest residues in the field. Content Type Journal Article Category Regular Article Pages 1-11 DOI 10.1007/s11104-012-1481-3 Authors Charlotte Toenshoff, Department of Soil Biology and Plant Nutrition, University of Kassel, Nordbahnhofstr. 1a, 37213 Witzenhausen, Germany Reinhold Stuelpnagel, Department of Grassland Science and Renewable Plant Resources, University of Kassel, Steinstr. 19, 37213 Witzenhausen, Germany Rainer Georg Joergensen, Department of Soil Biology and Plant Nutrition, University of Kassel, Nordbahnhofstr. 1a, 37213 Witzenhausen, Germany Christine Wachendorf, Department of Soil Biology and Plant Nutrition, University of Kassel, Nordbahnhofstr. 1a, 37213 Witzenhausen, Germany Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background and Aims   Rising costs and pressure on supplies of commercial mineral fertilizers and increasing markets for organically produced foods and feeds have led to a growing interest in soil amendments to supply plant nutrients. Rockdust is a by-product of quarrying and its effectiveness to supply plants with nutrients has been a contested issue and there have been no assessments of its effect on soil biota other than plants. The aim of this study was to assess the effect of a commercially-available volcanic rockdust application on crop growth and element concentrations for a wide range of macro and microelements and the response of soil microbial communities to rockdust due to the potential alteration in soil mineralogy. Methods   A three-year controlled outdoor-growing experiment was conducted on three different soil types with two wheat cultivars in the first year following rockdust application and with forage species in the third year. Results   Our results show that the tested rockdust had no positive or negative effect on plant growth or nutrient composition. In addition, the microbial response to added substrates, a sensitive measure of changes in soil environment, were unaltered by the rockdust. Conclusions   As the rockdust had no nutrient or toxic effect it can probably be considered as an inert material which at least causes no harm but equally has no demonstrable ecological or agricultural benefit. Content Type Journal Article Category Regular Article Pages 1-18 DOI 10.1007/s11104-012-1474-2 Authors Atefeh Ramezanian, Department of Crop Production Ecology, Swedish University of Agricultural Sciences, Box 7043, Ulls väg 16, 750 07 Uppsala, Sweden A. Sigrun Dahlin, Department of Soil and Environment, Swedish University of Agricultural Sciences, Box 7014, 750 07 Uppsala, Sweden Colin D. Campbell, Department of Soil and Environment, Swedish University of Agricultural Sciences, Box 7014, 750 07 Uppsala, Sweden Stephen Hillier, The James Hutton Institute, Craigiebuckler, Aberdeen, AB15 8QH Scotland, UK Birgitta Mannerstedt-Fogelfors, Department of Crop Production Ecology, Swedish University of Agricultural Sciences, Box 7043, Ulls väg 16, 750 07 Uppsala, Sweden Ingrid Öborn, Department of Crop Production Ecology, Swedish University of Agricultural Sciences, Box 7043, Ulls väg 16, 750 07 Uppsala, Sweden Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background and aims   Copper (Cu) is an essential micronutrient required for growth and development of plants. However, excess Cu is toxic to plants. To understand the mechanisms involved in copper stress response, a proteomic approach was used to investigate the differences in Cu stress-induced protein expression between a Cu-tolerant variety (B1139) and a Cu-sensitive one (B1195) of rice. Methods   Rice seedlings were exposed to 8 μM Cu for 3 days, with plants grown in the normal nutrient solution containing 0.32 μM Cu serving as the control. Proteins were extracted from the roots and separated by two-dimensional PAGE. Thirty four proteins were identified using MALDI-TOF mass spectrometry. Results   Thirty-four protein spots were found to be differently expressed in the Cu-stressed roots in at least one variety of rice, including those involved in antioxidative defense, redox regulation, stress response, sulfur and glutathione (GSH) metabolism, carbohydrate metabolism, signal transduction, and some other proteins with various functions. Nine proteins, including putative cysteine synthase, probable serine acetyltransferase 3, L-ascorbate peroxidase 1, putative glutathione S-transferase 2, and thioredoxin-like 3-3, exhibited a greater increase in response to Cu stress in the Cu-tolerant variety B1139 compared with the Cu–sensitive variety B1195. Conclusion   The majority of the proteins showing differential expression in response to Cu exposure are involved in the redox regulation, and sulfur and GSH metabolism, suggesting that these proteins, together with antioxidant enzymes, play an important role in the detoxification of excess Cu and maintaining cellular homeostasis. Content Type Journal Article Category Regular Article Pages 1-12 DOI 10.1007/s11104-012-1458-2 Authors Yufeng Song, College of Life Sciences, Nanjing Agricultural University, Nanjing, 210095 the People’s Republic of China Jin Cui, College of Life Sciences, Nanjing Agricultural University, Nanjing, 210095 the People’s Republic of China Hongxiao Zhang, College of Agricultural, Henan University of Science and Technology, Luoyang, 471003 the People’s Republic of China Guiping Wang, College of Life Sciences, Nanjing Agricultural University, Nanjing, 210095 the People’s Republic of China Fang-Jie Zhao, College of Resources and Environmental Science, Nanjing Agricultural University, Nanjing, 210095 the People’s Republic of China Zhenguo Shen, College of Life Sciences, Nanjing Agricultural University, Nanjing, 210095 the People’s Republic of China Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background and Aims   Bioavailable phosphorus (P) represents a primary constraint on productivity in many ecosystems on highly-weathered soils. Soil moisture can be important to determining P bioavailability and net primary productivity in these systems. However, hydrologic controls on P availability remain poorly understood. Methods   We used “resins” (anion-exchange membranes) to quantify the response of labile P, an estimate of bioavailable P, to soil moisture conditions in two highly-weathered soils (rendzina, ultisol). The resins were either incubated in soil or shaken with a soil-water slurry. Results   Resin incubations in aerobic soil effectively quantified labile P in soils under changing moisture conditions, extracting significant amounts of labile P while avoiding the disturbance imposed by slurries. Wetting field-moist soils resulted in pulsed labile P, with lagged peaks occurring days after the largest moisture additions. Re-wetting air-dried soils enhanced labile P immediately, with the largest amounts observed at the highest moisture levels; labile P steadily declined following the moisture addition. Conclusions   Soil moisture levels and history strongly impacted labile P, indicating the importance of both variables when interpreting labile P measurements. These results also suggest that P availability is linked to both the amount and timing of rainfall, with implications for plant productivity in regions exposed to changing moisture regimes. Content Type Journal Article Category Regular Article Pages 1-9 DOI 10.1007/s11104-012-1373-6 Authors Marcia DeLonge, Department of Environmental Sciences, University of Virginia, PO Box 400123, Charlottesville, VA 22904-4123, USA Karen L. Vandecar, Department of Environmental Sciences, University of Virginia, PO Box 400123, Charlottesville, VA 22904-4123, USA Paolo D’Odorico, Department of Environmental Sciences, University of Virginia, PO Box 400123, Charlottesville, VA 22904-4123, USA Deborah Lawrence, Department of Environmental Sciences, University of Virginia, PO Box 400123, Charlottesville, VA 22904-4123, USA Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background and Aims   We developed a method for processing roots from soil cores and monoliths in the laboratory to reduce the time and cost devoted to separating roots from debris and improve the accuracy of root variable estimates. The method was tested on soil cores from a California oak savanna, with roots from trees, Quercus douglasii, and annual grasses. Methods   In the randomized sampling method, one isolates the sample fraction consisting of roots and organic debris 〈 = 1 cm in length, and randomizes it through immersion in water and vigorous mixing. Sub-samples from the mixture are then used to estimate the percentage of roots in this fraction, thereby enabling an estimate of total sample biomass. Results   We found that root biomass estimates, determined through the randomization method, differed from total root biomass established by meticulously picking every root from a sample with an error of 3.0 % +/− 0.6 % s.e. Conclusions   This method greatly reduces the time and resources required for root processing from soil cores and monoliths, and improves the accuracy of root variable estimates compared to standard methods. This gives researchers the ability to increase sample frequency and reduce the error associated with studying roots at the landscape and plant scales. Content Type Journal Article Category Regular Article Pages 1-16 DOI 10.1007/s11104-012-1350-0 Authors Laura E. Koteen, Department of Environmental Science, Policy and Management, University of California, Berkeley, CA 94720-3114, USA Dennis D. Baldocchi, Department of Environmental Science, Policy and Management, University of California, Berkeley, CA 94720-3114, USA Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background and aims   Biochar additions to tropical soils have been shown to reduce N leaching and increase N use efficiency. No studies exist verifying reduced N leaching in field experiments on temperate agricultural soils or identifying the mechanism for N retention. Methods   Biochar derived from maize stover was applied to a maize cropping system in central New York State at rates of 0, 1, 3, 12, and 30 t ha -1 in 2007. Secondary N fertilizer was added at 100, 90, 70, and 50 % of the recommended rate (108 kg N ha -1 ). Nitrogen fertilizer enriched with 15  N was applied in 2009 to the 0 and 12 t ha -1 of biochar at 100 and 50 % secondary N application. Results   Maize yield and plant N uptake did not change with biochar additions ( p  〉 0.05; n  = 3). Less N (by 82 %; p  〈 0.05) was lost after biochar application through leaching only at 100 % N fertilization. The reason for an observed 140 % greater retention of applied 15  N in the topsoil may have been the incorporation of added 15  N into microbial biomass which increased approximately three-fold which warrants further research. The low leaching of applied fertilizer 15  N (0.42 % of applied N; p  〈 0.05) and comparatively high recovery of applied 15  N in the soil (39 %) after biochar additions after one cropping season may also indicate greater overall N retention through lower gaseous or erosion N losses with biochar. Conclusions   Addition of biochar to fertile soil in a temperate climate did not improve crop growth or N use efficiency, but increased retention of fertilizer N in the topsoil. Content Type Journal Article Category Regular Article Pages 1-16 DOI 10.1007/s11104-012-1383-4 Authors David Güereña, Department of Crop and Soil Sciences, Cornell University, Ithaca, NY 14853, USA Johannes Lehmann, Department of Crop and Soil Sciences, Cornell University, Ithaca, NY 14853, USA Kelly Hanley, Department of Crop and Soil Sciences, Cornell University, Ithaca, NY 14853, USA Akio Enders, Department of Crop and Soil Sciences, Cornell University, Ithaca, NY 14853, USA Charles Hyland, Department of Crop and Soil Sciences, Cornell University, Ithaca, NY 14853, USA Susan Riha, Department of Earth and Atmospheric Sciences, Cornell University, Ithaca, NY 14853, USA Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background and aims   Efficient accumulation of arsenic (As) in rice ( Oryza sativa L.) poses a potential health risk to rice consumers. The aim of this study was to investigate the mechanisms of uptake, transport and distribution of inorganic arsenic (As i ) and dimethylarsinic acid (DMA) in rice plants. Methods   Rice was exposed to As i (As(V)) and DMA in hydroponics. High-performance liquid chromatography inductively coupled plasma mass spectrometry (HPLC-ICP-MS) and synchrotron X-ray fluorescence (SXRF) microprobe were used to determine As concentration and the in situ As distribution. Results   DMA induced abnormal florets before flowering and caused a sharp decline in the seed setting rate after flowering compared to As i . Rice grains accumulated 2-fold higher DMA than As i . The distribution of As i concentration (root 〉 leaf 〉 husk 〉 caryopsis) in As(V) treatments was different from that of the DMA concentration (caryopsis 〉 husk 〉 root ≥ leaf) in DMA treatments. SXRF showed that As i mainly accumulated in the vascular trace of caryopsis with limited distribution to the endosperm, whereas DMA was observed in both tissues. Conclusions   DMA tended to accumulate in caryopsis and induced higher toxicity to the reproductive tissues resulting in markedly reduced grain yield, whereas As i mainly remained in the vegetative tissues and had no significant effect on yield. DMA is more toxic than As i to the reproductive tissues when both of them are at similar concentrations in nutrient solution. Content Type Journal Article Category Regular Article Pages 1-12 DOI 10.1007/s11104-012-1376-3 Authors Mao-Zhong Zheng, Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021 China Gang Li, Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021 China Guo-Xin Sun, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085 China Hojae Shim, University of Macau, Taipa, Macau SAR, China Chao Cai, Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021 China Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Aims   Common bean is a major source of protein for many people worldwide. However, the crop is often subjected to drought conditions and its advantage in undertaking symbiotic nitrogen fixation can be severely decreased. The primary objective of this study was to compare the resistance of nitrogen fixation of 12 selected genotypes to soil drying. Methods   Twelve common bean genotypes of diverse genetic background were compared. Plants were grown in pots and subjected to soil drying over about 2 weeks. Nitrogen fixation was measured daily using a flow-through acetylene reduction technique. The plants were exposed to acetylene for only a short time period allowing repeated measures. The acetylene reduction rate of plants on drying soil was normalized against the rates measured for well-watered plants. Results   Substantial variability was identified among genotypes in the threshold soil water content at which nitrogen fixation was observed to decrease. Genotypes SER 16, SXB 412, NCB 226, and Calima were found to have the greatest delay in their decrease in nitrogen fixation rates based on soil water content. These four genotypes expressed substantial tolerance of nitrogen fixation to soil drying. These experiments also resulted in data on the threshold soil water contents at which transpiration rates decreased. A decrease in transpiration rates at high soil water contents is potentially advantageous since it allows soil water conservation for use as the severity of the drought increases. There was a general trend of those genotypes with sustained nitrogen fixation rates to low soil water contents also expressing decreased transpiration rates at high soil water contents. Conclusions   This study identified genetic variation among common bean genotypes in their response of nitrogen fixation and transpiration to soil drying. Five genotypes (SER 16, SXB 412, NCB 226, Calima, and SEA 5) expressed the desired traits for water-limited conditions, which might be exploited in breeding efforts. Content Type Journal Article Category Regular Article Pages 1-9 DOI 10.1007/s11104-012-1330-4 Authors Mura Jyostna Devi, Crop Science Department, North Carolina State University, Raleigh, NC, USA Thomas R. Sinclair, Crop Science Department, North Carolina State University, Raleigh, NC, USA Stephen E. Beebe, Centro Internacional de Agricultura Tropical (CIAT), A. A. 6713, Cali, Colombia Idupulapati M. Rao, Centro Internacional de Agricultura Tropical (CIAT), A. A. 6713, Cali, Colombia Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background and aims   The vertical distribution of available phosphorus (P) in the soil is usually heterogeneous with soil depth. However, little is known about the P efficiency of conifer species under vertically heterogeneous low-P conditions. The purpose of this study was to investigate the genetic variations in growth traits and P efficiency of Pinus massoniana , under heterogeneous and homogeneous low-P conditions. Methods   Pot experiments consisting of low-P (a low P level in all soil layers), layered-P (a high P level in the topsoil and a low P level in the bottom soil), and high-P (high P levels in all soil layers) conditions were designed and conducted. Three-way ANOVA was used to investigate genetic variations in P efficiency and the major growth traits under these three types of P conditions. Results   There were substantial genetic variations in the major growth traits, including tree height, stem diameter and seedling dry weight, under both heterogeneous and homogeneous low-P conditions. The heritability for major growth traits was high under both types of low-P condition. Moreover, there were significant genotype × P interaction effects for growth parameters. Conclusions   Our results indicate that it may be possible to select Masson pine genotypes with high P efficiency and productivity. The significant genotype × environment interactions should be exploited in breeding, and genotypes showing specific adaptations to certain nutrient environments should be bred and used within that environment. Content Type Journal Article Category Regular Article Pages 1-12 DOI 10.1007/s11104-012-1352-y Authors Yi Zhang, Research Institute of Subtropical Forestry, Chinese Academy of Forestry, Daqiao road, 73#, Fu Yang, Zhe Jiang, People’s Republic of China Zhichun Zhou, Research Institute of Subtropical Forestry, Chinese Academy of Forestry, Daqiao road, 73#, Fu Yang, Zhe Jiang, People’s Republic of China Qing Yang, Research Institute of Subtropical Forestry, Chinese Academy of Forestry, Daqiao road, 73#, Fu Yang, Zhe Jiang, People’s Republic of China Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Purpose   This study investigated the residual contribution of legume and fertilizer nitrogen (N) to a subsequent crop under the effect of elevated carbon dioxide concentration ([CO 2 ]). Methods   Field pea ( Pisum sativum L.) was labeled in situ with 15 N (by absorption of a 15 N-labeled urea solution through cut tendrils) under ambient and elevated (700 μmol mol –1 ) [CO 2 ] in controlled environment glasshouse chambers. Barley ( Hordeum vulgare L.) and its soil were also labeled under the same conditions by addition of 15 N-enriched urea to the soil. Wheat ( Triticum aestivum L.) was subsequently grown to physiological maturity on the soil containing either 15 N-labeled field pea residues (including 15 N-labeled rhizodeposits) or 15 N-labeled barley plus fertilizer 15 N residues. Results   Elevated [CO 2 ] increased the total biomass of field pea (21 %) and N-fertilized barley (23 %), but did not significantly affect the biomass of unfertilized barley. Elevated [CO 2 ] increased the C:N ratio of residues of field pea (18 %) and N-fertilized barley (19 %), but had no significant effect on that of unfertilized barley. Elevated [CO 2 ] increased total biomass (11 %) and grain yield (40 %) of subsequent wheat crop regardless of rotation type in the first phase. Irrespective of [CO 2 ], the grain yield and total N uptake by wheat following field pea were 24 % and 11 %, respectively, higher than those of the wheat following N-fertilized barley. The residual N contribution from field pea to wheat was 20 % under ambient [CO 2 ], but dropped to 11 % under elevated [CO 2 ], while that from fertilizer did not differ significantly between ambient [CO 2 ] (4 %) and elevated [CO 2 ] (5 %). Conclusions   The relative value of legume derived N to subsequent cereals may be reduced under elevated [CO 2 ]. However, compared to N fertilizer application, legume incorporation will be more beneficial to grain yield and N supply to subsequent cereals under future (elevated [CO 2 ]) climates. Content Type Journal Article Category Regular Article Pages 1-11 DOI 10.1007/s11104-012-1314-4 Authors Shu Kee Lam, Melbourne School of Land and Environment, The University of Melbourne, Victoria, 3010 Australia Deli Chen, Melbourne School of Land and Environment, The University of Melbourne, Victoria, 3010 Australia Rob Norton, Melbourne School of Land and Environment, The University of Melbourne, Victoria, 3010 Australia Roger Armstrong, Department of Primary Industries, Private Bag 260, Horsham, Victoria 3401, Australia Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background and Aims   Forest trees directly contribute to carbon cycling in forest soils through the turnover of their fine roots. In this study we aimed to calculate root turnover rates of common European forest tree species and to compare them with most frequently published values. Methods   We compiled available European data and applied various turnover rate calculation methods to the resulting database. We used Decision Matrix and Maximum-Minimum formula as suggested in the literature. Results   Mean turnover rates obtained by the combination of sequential coring and Decision Matrix were 0.86 yr −1 for Fagus sylvatica and 0.88 yr −1 for Picea abies when maximum biomass data were used for the calculation, and 1.11 yr −1 for both species when mean biomass data were used. Using mean biomass rather than maximum resulted in about 30 % higher values of root turnover. Using the Decision Matrix to calculate turnover rate doubled the rates when compared to the Maximum-Minimum formula. The Decision Matrix, however, makes use of more input information than the Maximum-Minimum formula. Conclusions   We propose that calculations using the Decision Matrix with mean biomass give the most reliable estimates of root turnover rates in European forests and should preferentially be used in models and C reporting. Content Type Journal Article Category Review Article Pages 1-16 DOI 10.1007/s11104-012-1313-5 Authors I. Brunner, Swiss Federal Institute for Forest, Snow and Landscape Research WSL, 8903 Birmensdorf, Switzerland M. R. Bakker, University of Bordeaux, UMR1220 TCEM, 33175 Gradignan, France R. G. Björk, Department of Biological and Environmental Sciences, University of Gothenburg, P.O. Box 461, 405 30 Gothenburg, Sweden Y. Hirano, Graduate School of Environmental Studies, Nagoya University, Nagoya, 464-8601 Japan M. Lukac, School of Agriculture, Policy and Development, University of Reading, Reading, RG6 6AR UK X. Aranda, Ecophysiology, IRTA Torre Marimon, 08140 Caldes de Montbui, Spain I. Børja, Norwegian Forest and Landscape Institute, P.O. Box 115, 1431 Ås, Norway T. D. Eldhuset, Norwegian Forest and Landscape Institute, P.O. Box 115, 1431 Ås, Norway H. S. Helmisaari, Department of Forest Sciences, University of Helsinki, P.O. Box 27, 00014 Helsinki, Finland C. Jourdan, CIRAD, UMR Eco&Sols, 2, Place Pierre Viala, 34060 Montpellier, France B. Konôpka, Forest Research Institute, National Forest Centre, 96001 Zvolen, Slovak Republic B. C. López, CREAF Center for Ecological Research and Forestry Applications, and Ecology Unit of the Department of Plant and Animal Biology and Ecology, Edifici Ciències UAB, 08193 Bellaterra, Spain C. Miguel Pérez, Ecophysiology, IRTA Torre Marimon, 08140 Caldes de Montbui, Spain H. Persson, Department of Ecology, Swedish University of Agricultural Sciences SLU, P.O. Box 7044, 750 07 Uppsala, Sweden I. Ostonen, Institute of Ecology and Earth Sciences, University of Tartu, Vanemuise 46, 51014 Tartu, Estonia Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Aims   Decreasing mineral concentrations in high-yield grains of the Green Revolution have coincided in time with rising global cardiovascular disease (CVD) mortality rates. Given the Magnesium (Mg) Hypothesis of CVD, it’s important to assess any changes in food crop Mg concentrations over the past 50+ years. Methods   Using current and historical published sources, Mg concentrations in “old” and “new” wheats, fruits and vegetables were listed/calculated (dry weight basis) and applied to reports of USA’s historic Mg supply, 1900–2006. Resulting trend in USA Mg supply was compared with USA trend in CVD mortality. Human Mg intake studies, old and new, were compared with the range of reported human Mg requirements. Results   Acknowledging assessment difficulties, since the 1850s, wheats have declined in Mg concentration 7–29 %; USA and English vegetables’ Mg declined 15–23 %, 1930s to 1980s. The nadir of USA food Mg supply in 1968 coincides with the USA peak in CVD mortality. As humans transition from “traditional” to modern processed food diets, Mg intake declines. Conclusions   Rising global CVD mortality may be linked to lower Mg intakes as world populations transition from traditional high Mg foods to those low in Mg due to declining crop Mg and processing losses. Content Type Journal Article Category Regular Article Pages 1-15 DOI 10.1007/s11104-012-1471-5 Authors Andrea Rosanoff, Center for Magnesium Education & Research, LLC, 13-1255 Malama St., Pahoa, HI 96778, USA Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Aims   Metallothioneins are cysteine-rich, metal-binding proteins, but their exact functions are not fully understood. In this study, we isolated two metallothionein genes, BcMT1 and BcMT2 from Brassica campestris to increase our understanding of metal tolerance mechanisms in Brassica plants. Methods   Semi-quantitative RT-PCR was used to analyze expression of the two BcMTs genes. BcMT1 and BcMT2 were ectopically expressed in Arabidopsis thaliana . Quantitative real-time RT-PCR and GUS-staining method were used to select transgenic Arabidopsis plants. Cd and Cu concentrations were analyzed by flame atomic absorption spectrometry. Histochemical detection of H 2 O 2 and O 2 •− were conducted by 3,3-diaminobenzidine and nitroblue tetrazoliu-staining methods. Results   BcMT1 is expressed predominantly in roots, whereas BcMT2 is expressed mainly in leaves of B . campestris . Expression of BcMT1 was induced by both Cd and Cu, but expression of BcMT2 was enhanced only by Cd. Ectopic expression of BcMT1 and BcMT2 in Arabidopsis thaliana enhanced the tolerance to Cd and Cu and increased the Cu concentration in the shoots of the transgenic plants. Transgenic Arabidopsis accumulated less reactive oxygen species (ROS) than wild-type plants. Conclusions   BcMT1 and BcMT2 increased Cd and Cu tolerance in transgenic Arabidopsis , and decreased production of Cd- and Cu-induced ROS, thereby protecting plants from oxidative damage. Content Type Journal Article Category Regular Article Pages 1-13 DOI 10.1007/s11104-012-1486-y Authors Yanyan Lv, College of Life Sciences, Nanjing Agricultural University, Nanjing, 210095 China Xiaopeng Deng, Yunnan Academy of Tobacco Agricultural Sciences and China Tobacco Breeding Research (Southern) Center, Yuxi, 653100 China Lingtong Quan, College of Life Sciences, Nanjing Agricultural University, Nanjing, 210095 China Yan Xia, College of Life Sciences, Nanjing Agricultural University, Nanjing, 210095 China Zhenguo Shen, College of Life Sciences, Nanjing Agricultural University, Nanjing, 210095 China Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background and Aims   Evidence shows that plants modify their microbial environment leading to the “crop rotation effect”, but little is known about the changes in rhizobacterial community structure and functionality associated with beneficial rotation effects. Methods   Polymerase chain reaction (PCR) and 454 GS FLX amplicon pyrosequencing were used to describe the composition of the rhizobacterial community evolving under the influence of pea, a growth promoting rotation crop, and the influence of three genotypes of chickpea, a plant known as an inferior rotation crop. The growth promoting properties of these rhizobacterial communities were tested on wheat in greenhouse assays. Results   The rhizobacterial communities selected by pea and the chickpea CDC Luna in 2008, a wet year, promoted durum wheat growth, but those selected by CDC Vanguard or CDC Frontier had no growth-promoting effect. In 2009, a dry year, the influence of plants was mitigated, indicated that moisture availability is a major driver of soil bacterial community dynamics. Conclusion   The effect of pulse crops on soil biological quality varies with the crop species and genotypes, and certain chickpea genotypes may induce positive rotation effects on wheat. The strength of a rotation effect on soil biological quality is modulated by the abundance of precipitation. Content Type Journal Article Category Regular Article Pages 1-13 DOI 10.1007/s11104-012-1485-z Authors Chao Yang, Semiarid Prairie Agricultural Research Centre, Agriculture and Agri-Food Canada, 1030, 1st Airport Road, Swift Current, SK, Canada S9H 3X2 Chantal Hamel, Semiarid Prairie Agricultural Research Centre, Agriculture and Agri-Food Canada, 1030, 1st Airport Road, Swift Current, SK, Canada S9H 3X2 Yantai Gan, Semiarid Prairie Agricultural Research Centre, Agriculture and Agri-Food Canada, 1030, 1st Airport Road, Swift Current, SK, Canada S9H 3X2 Vladimir Vujanovic, Department of Food & Bioproducts Sciences, University of Saskatchewan, Saskatoon, SK, Canada Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background and aims   We studied the response of lignin oxidation in soils of a beech/oak forest to changes in litter fall. Additionally we considered possible factors in lignin oxidation, including altered (i) input of fresh organic matter and (ii) fungi-to-bacteria ratios. Methods   The field-based experiment included (i) doubling and (ii) exclusion of litter fall and (iii) controls with ambient litter fall. Soil (0–20 cm depth) was sampled after 8 years. We analyzed (i) lignin using the CuO oxidation method, (ii) stocks of free and mineral-bound organic carbon (OC), (iii) the response of soil organic matter (SOM) decomposition to addition of labile organic compounds in laboratory incubations, and (iv) ratios of fungal- vs. bacterial-derived amino sugars (F/B ratios). Results   Litter exclusion increased stocks of free-light fraction OC, F/B ratios, the ability of the microbial community to use labile compounds for SOM decomposition, as well as acid-to-aldehyde ratios of vanillyl-type lignin phenols in A horizons. Litter addition had no such effects. We assume that litter exclusion caused enhanced transport of organic debris from lower forest floor horizons with rainwater into the A horizon. Enhanced input of organic debris might have increased (i) the availability of labile compounds and (ii) F/B ratios. Consequently, lignin oxidation increased. Conclusions   Enhanced input of organic debris from forest floors can increase lignin oxidation in mineral topsoils of the studied forest. The expected gradual changes in litter fall due to climate change likely will cause no such effects. Content Type Journal Article Category Regular Article Pages 1-11 DOI 10.1007/s11104-012-1489-8 Authors Thimo Klotzbücher, Earth Surface Science, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Amsterdam, The Netherlands Stefan Strohmeier, Soil Ecology, University of Bayreuth, Bayreuth, Germany Klaus Kaiser, Soil Sciences, Martin Luther University Halle-Wittenberg, Halle, Germany Richard D. Bowden, Department of Environmental Science, Allegheny College, Meadville, PA, USA Kate Lajtha, Botany and Plant Pathology Department, Oregon State University, Corvallis, OR, USA Heike Ohm, Department of Soil Science/Soil Ecology, Institute of Geography, Ruhr-University Bochum, Bochum, Germany Karsten Kalbitz, Earth Surface Science, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Amsterdam, The Netherlands Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Aims   We used a Procrustean superimposition approach associated with regression analysis to test hypotheses regarding the relationship between plant communities and distinct below-ground compartments—soil chemistry (SC) and soil microbial activity (SMA). Additionally, we evaluated litter chemical quality as an interface between the above and below-ground compartments. Methods   Plant community, and soil chemical and biochemical data from three post-mining degraded sites under reclamation and from one nearby forest site in the Brazilian Amazon Basin were analyzed. Results   All studied sites presented distinct plant community, litter quality, SC and SMA. Plant community consistently affected the below-ground variation in both SC and SMA compartments. The influence of litter quality was greater in the plant community versus SMA relationship than in the plant community versus SC. Nevertheless, the SC affected significantly the SMA, but without influence of litter quality. Conclusions   Differently from previous studies, our findings suggest that plant community and soil chemistry can affect the soil microbial activity independently. Specifically for our study area, these results point to a rupture of the ‘in nested’ structure of the causal relationship between changes in vegetation, changes in the chemical litter quality, changes in the SC and the response of SMA. Content Type Journal Article Category Regular Article Pages 1-12 DOI 10.1007/s11104-012-1491-1 Authors Francy J. G. Lisboa, Soil Science Department, Institute of Agronomy, Federal Rural University of Rio de Janeiro, BR 465, km 7, Seropédica, RJ, Brazil Guilherme M. Chaer, Embrapa Agrobiologia, BR 465, km 7, Seropédica, RJ, Brazil Ederson da C. Jesus, Embrapa Agrobiologia, BR 465, km 7, Seropédica, RJ, Brazil Sérgio M. de Faria, Embrapa Agrobiologia, BR 465, km 7, Seropédica, RJ, Brazil Fernando S. Gonçalves, Forests Institute, Federal Rural University of Rio de Janeiro, BR 465, km 7, Seropédica, RJ, Brazil Felipe M. Santos, Forests Institute, Federal Rural University of Rio de Janeiro, BR 465, km 7, Seropédica, RJ, Brazil Alexandre F. Castilho, Environmental Management Department of Vale S/A (GABAM), Núcleo Urbano Carajás, Parauapebas, PA, Brazil Ricardo L. L. Berbara, Soil Science Department, Institute of Agronomy, Federal Rural University of Rio de Janeiro, BR 465, km 7, Seropédica, RJ, Brazil Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background and aims   Climate warming has the potential to increase both the exposure and vulnerability of grass roots to frost in temperate regions by reducing snow cover and altering the timing of cold acclimation. Despite a strong research focus on the direct effects of freezing on grass mortality, the direct sub-lethal effects of freezing on grass performance have not been well-characterized. We examined sub-lethal responses of the grass Poa pratensis to variation in the timing, severity, rate and length of freezing. Methods   We assessed short term root functional responses ( 15 N uptake) and longer term plant growth responses to freezing administered both under controlled conditions in a refrigerated incubator, and in the field by manipulating snow and litter cover. Results   In fall and spring, 15 N uptake declined in response to 1 day of freezing down to −10 °C or to 3 days of freezing at −5 °C, whereas in winter, 15 N uptake was insensitive to freezing. Long term growth responses were similar, with reduced growth only occurring for grasses frozen for 3 days at −5 °C in spring, but not for grasses frozen in fall or winter. Snow and litter removal intensified soil freezing over winter, but did not significantly affect plant growth. Conclusions   Our results demonstrate that while P. pratensis is relatively tolerant to frost damage over winter, it may be vulnerable to sub-lethal frost effects in fall, and particularly in spring. These sub-lethal effects occur at temperatures approximately 15–20 °C warmer than the published LT 50 values for this species. Content Type Journal Article Category Regular Article Pages 1-11 DOI 10.1007/s11104-012-1233-4 Authors Andrey V. Malyshev, Department of Biology, University of Western Ontario, London, Ontario N6A 5B7, Canada Hugh A. L. Henry, Department of Biology, University of Western Ontario, London, Ontario N6A 5B7, Canada Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background and aim   Concentrations of essential minerals in plant foods may have declined in modern high-yielding cultivars grown with large applications of nitrogen fertilizer (N). We investigated the effect of dwarfing alleles and N rate on mineral concentrations in wheat. Methods   Gibberellin (GA)-insensitive reduced height ( Rht ) alleles were compared in near isogenic wheat lines. Two field experiments comprised factorial combinations of wheat variety backgrounds, alleles at the Rht-B1 locus ( rht-B1a , Rht-B1b , Rht-B1c ), and different N rates. A glasshouse experiment also included Rht-D1b and Rht-B1b+D1b in one background. Results   In the field, depending on season, Rht-B1b increased crop biomass, dry matter (DM) harvest index, grain yield, and the economically-optimal N rate ( N opt ). Rht-B1b did not increase uptake of Cu, Fe, Mg or Zn so these minerals were diluted in grain. Nitrogen increased DM yield and mineral uptake so grain concentrations were increased (Fe in both seasons; Cu, Mg and Zn in one season). Rht-B1b reduced mineral concentrations at N opt in the most N responsive season. In the glasshouse experiment, grain yield was reduced, and mineral concentrations increased, with Rht allele addition. Conclusion   Effects of Rht alleles on Fe, Zn, Cu and Mg concentrations in wheat grain are mostly due to their effects on DM, rather than of GA-insensitivity on N opt or mineral uptake. Increased N requirement in semi-dwarf varieties partly offsets this dilution effect. Content Type Journal Article Category Regular Article Pages 1-15 DOI 10.1007/s11104-012-1203-x Authors Mike J. Gooding, School of Agriculture, Policy and Development, The University of Reading, Earley Gate, Reading, RG6 6AR UK Mingsheng Fan, Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ, UK Steve P. McGrath, Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ, UK Peter R. Shewry, Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ, UK Fang-Jie Zhao, Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ, UK Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background and aims   The loss of iron and zinc during milling to produce white rice can have serious consequences for human health. Therefore, the objective was to evaluate Fe and Zn partitioning between the endosperm, bran and embryo, and the milling loss of these nutrients among Thai rice genotypes. Methods   Concentrations of iron and zinc and their partitioning to different parts of the grain were examined in 15 genotypes of Thai rice (10 belonging to the long-slender grain type) grown together under wetland condition. Results   The depression in grain Fe and Zn concentrations (24–60 and 10–58 %, respectively) on milling differed among rice genotypes and were affected by the extent of differential partitioning of Fe and Zn into different parts of the grain. For example, nearly 70 % of white rice Zn was allocated to the endosperm in contrast to only 43 % for Fe. Conclusions   Because of variation in milling loss of Fe and Zn, that can result from genotypic variation in the degree of milling and partitioning of Fe and Zn into different parts of the grain, we conclude that white rice Fe and Zn concentrations should not be inferred solely from brown rice concentrations of these nutrients. Content Type Journal Article Category Regular Article Pages 1-8 DOI 10.1007/s11104-012-1228-1 Authors Chorpet Saenchai, Division of Agronomy, Department of Plant Science and Natural Resources, Faculty of Agriculture, Chiang Mai University, Chiang Mai, 50200 Thailand Chanakan Prom-u-thai, Division of Agronomy, Department of Plant Science and Natural Resources, Faculty of Agriculture, Chiang Mai University, Chiang Mai, 50200 Thailand Sansanee Jamjod, Division of Agronomy, Department of Plant Science and Natural Resources, Faculty of Agriculture, Chiang Mai University, Chiang Mai, 50200 Thailand Bernard Dell, Sustainable Ecosystem Research Institute, Murdoch University, Perth, 6150 Australia Benjavan Rerkasem, Plant Genetic Resource and Nutrition Laboratory, Chiang Mai University, Chiang Mai, 50200 Thailand Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background and aims   Although changes in water and nitrogen (N) supply have been largely used to explain modifications in plant communities, the spatio-temporal variability of those factors has been little studied in chalky environments. Methods   In this study, we explored for 1 year the temporal variations in soil water content, N inorganic forms and net N-mineralization and nitrification for two horizons in three herbaceous communities (short grasslands, tall grasslands, and encroached grasslands) in the Hénouville Nature Reserve (Upper-Normandy, France). Plant available soil water and permanent wilting points of seven plant species were also characterized. Results   We found that plant available soil water was lower in short grasslands than in tall grasslands and encroached grasslands. Soil water content was below permanent wilting point during four months in short grasslands and only three months in the other communities. Seasonal patterns for inorganic N content and N-mineralization and nitrification were observed with peaks of NH 4 + –N in summer and peaks of N-mineralization in spring. Conclusions   For the studied year, our data highlight the harsh soil desiccation that vegetation endured during the late spring (active growth period) and summer, and show that water shortage is an ecological factor affecting the N cycling in the three successional herbaceous communities. Content Type Journal Article Category Review Article Pages 1-17 DOI 10.1007/s11104-012-1234-3 Authors Gaylord Dujardin, Laboratoire d’Ecologie, EA 1293 ECODIV, Structure Fédérative de Recherche SCALE, Bâtiment IRESE A, UFR Sciences et Techniques, Université de Rouen, 76821 Mont Saint Aignan cedex, France Fabrice Bureau, Laboratoire d’Ecologie, EA 1293 ECODIV, Structure Fédérative de Recherche SCALE, Bâtiment IRESE A, UFR Sciences et Techniques, Université de Rouen, 76821 Mont Saint Aignan cedex, France Marthe Vinceslas-Akpa, Laboratoire d’Ecologie, EA 1293 ECODIV, Structure Fédérative de Recherche SCALE, Bâtiment IRESE A, UFR Sciences et Techniques, Université de Rouen, 76821 Mont Saint Aignan cedex, France Thibaud Decaëns, Laboratoire d’Ecologie, EA 1293 ECODIV, Structure Fédérative de Recherche SCALE, Bâtiment IRESE A, UFR Sciences et Techniques, Université de Rouen, 76821 Mont Saint Aignan cedex, France Estelle Langlois, Laboratoire d’Ecologie, EA 1293 ECODIV, Structure Fédérative de Recherche SCALE, Bâtiment IRESE A, UFR Sciences et Techniques, Université de Rouen, 76821 Mont Saint Aignan cedex, France Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background and aims   Long-term experiments could provide valuable information to determine the effects of an agronomic practice on agro-ecosystem productivity and stability. This study evaluated the long-term (18-year) impact of different tillage systems on faba bean ( Vicia faba L.) productivity, including weed and broomrape incidence, and N 2 fixation. Methods   The experiment was carried out on a Vertisol under rainfed Mediterranean conditions. It was set up as a strip-plot design. The tillage systems were: conventional tillage (CT) with moldboard plow, reduced tillage (RT) with chisel plow, and no tillage (NT). Nitrogen fixation was estimated over 2 years in the final phase of the experiment using the 15 N isotope dilution technique. Results   On average, grain yield was 31 % and 23 % higher under NT than under CT and RT, respectively; however, the effect of tillage varied by year. The yield advantage of NT over CT was pronounced when rainfall was scarce. Average broomrape infestation was lower under NT than under CT, but a reduction in tillage intensity resulted in an increase in weed biomass. Tillage had no effect on weed richness, but the use of the NT technique progressively altered the weed composition by determining conditions conducive to the growth of a few weed species that are hard to control. Nitrogen fixation was strongly influenced by tillage, being higher under NT than under CT. Conclusions   The results suggest that NT is a valuable option in the rainfed cereal–legume rotation systems of Mediterranean environments; however, the success of NT technique depends on the use of effective weed control strategies. Content Type Journal Article Category Regular Article Pages 1-13 DOI 10.1007/s11104-012-1224-5 Authors Dario Giambalvo, Dipartimento dei Sistemi Agro-Ambientali – Università di Palermo, Viale delle Scienze Edif. 4, 90128 Palermo, Italy Paolo Ruisi, Dipartimento dei Sistemi Agro-Ambientali – Università di Palermo, Viale delle Scienze Edif. 4, 90128 Palermo, Italy Sergio Saia, Dipartimento dei Sistemi Agro-Ambientali – Università di Palermo, Viale delle Scienze Edif. 4, 90128 Palermo, Italy Giuseppe Di Miceli, Dipartimento dei Sistemi Agro-Ambientali – Università di Palermo, Viale delle Scienze Edif. 4, 90128 Palermo, Italy Alfonso Salvatore Frenda, Dipartimento dei Sistemi Agro-Ambientali – Università di Palermo, Viale delle Scienze Edif. 4, 90128 Palermo, Italy Gaetano Amato, Dipartimento dei Sistemi Agro-Ambientali – Università di Palermo, Viale delle Scienze Edif. 4, 90128 Palermo, Italy Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background and aims   Malnutrition resulting from zinc (Zn) and iron (Fe) deficiency has become a global issue. Excessive phosphorus (P) application may aggravate this issue due to the interactions of P and micronutrients in soil crop. Crop grain micronutrients associated with P applications and the increase of grain Zn by Zn fertilization were field-evaluated. Methods   A field experiment with wheat was conducted to quantify the effect of P applications on grain micronutrient quality during two cropping seasons. The effect of foliar Zn applications on grain Zn quality with varied P applications was tested in 2011. Results   Phosphorus applications decreased grain Zn concentration by 17–56%, while grain levels of Fe, manganese (Mn) and copper (Cu) either remained the same or increased. Although P applications increased grain yield, they restricted the accumulation of shoot Zn, but enhanced the accumulation of shoot Fe, Cu and especially Mn. In 2011, foliar Zn application restored the grain Zn to levels occurring without P and Zn application, and consequently reduced the grain P/Zn molar ratio by 19–53% than that without Zn application. Conclusions   Foliar Zn application may be needed to achieve both favorable yield and grain Zn quality of wheat in production areas where soil P is building up. Content Type Journal Article Category Regular Article Pages 1-10 DOI 10.1007/s11104-012-1238-z Authors Yue-Qiang Zhang, Key Laboratory of Plant-Soil Interaction, MOE; Center for Resources, Environment and Food Security, China Agricultural University, Beijing, 100193 People’s Republic of China Yan Deng, Key Laboratory of Plant-Soil Interaction, MOE; Center for Resources, Environment and Food Security, China Agricultural University, Beijing, 100193 People’s Republic of China Ri-Yuan Chen, Key Laboratory of Plant-Soil Interaction, MOE; Center for Resources, Environment and Food Security, China Agricultural University, Beijing, 100193 People’s Republic of China Zhen-Ling Cui, Key Laboratory of Plant-Soil Interaction, MOE; Center for Resources, Environment and Food Security, China Agricultural University, Beijing, 100193 People’s Republic of China Xin-Ping Chen, Key Laboratory of Plant-Soil Interaction, MOE; Center for Resources, Environment and Food Security, China Agricultural University, Beijing, 100193 People’s Republic of China Russell Yost, Department of Tropical Plant and Soil Science, University of Hawai’i at Manoa, Honolulu, HI 96822, USA Fu-Suo Zhang, Key Laboratory of Plant-Soil Interaction, MOE; Center for Resources, Environment and Food Security, China Agricultural University, Beijing, 100193 People’s Republic of China Chun-Qin Zou, Key Laboratory of Plant-Soil Interaction, MOE; Center for Resources, Environment and Food Security, China Agricultural University, Beijing, 100193 People’s Republic of China Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Aim   Highly alkaline soils (pH 〉 9.0) may adversely affect agricultural crop productivity. Problems encountered include poor structure and nutrient deficiency. Research based on solution cultures suggests that aluminium (Al) phytotoxicity may occur in soils with pH 〉 9.0, but little research has been undertaken on actual soils under controlled conditions. The nature of the Al species responsible and the pH regime of the soils when this occurs are unknown. Methods   The charge and species of Al responsible for this toxicity was investigated using Zeta Potential measurement, Nuclear Magnetic Resonance (NMR) spectroscopy, Al precipitation characteristics and electrical conductivity as a function of pH. An anion exchange resin was used to evaluate Al availability to plants at alkaline pH. To verify Al phytotoxicity, a pot experiment was performed with plants grown at near neutral and high pH, with and without Al. Results   The anionic aluminate species of aluminium was ubiquitous at highly alkaline pH, and was the dominant charged species at pH 9.2. Aluminium was phytotoxic at high pH, significantly reducing the stem and root development of field pea test plants over and above that caused by alkalinity alone. The effects of both alkalinity in general and aluminium in particular became noticeable at pH 9.0 and debilitating at pH 〉 9.2. Conclusion   As this corresponds to the pH where aluminate becomes dominant, it is probably responsible for the phytotoxicity. Content Type Journal Article Category Regular Article Pages 1-10 DOI 10.1007/s11104-012-1232-5 Authors D. J. Brautigan, Soil and Land Systems, School of Earth and Environmental Sciences, The University of Adelaide, Waite campus, Urrbrae, South Australia 5064, Australia P. Rengasamy, Soil Group, School of Agriculture Food and Wine, The University of Adelaide, Waite campus, Urrbrae, South Australia 5064, Australia D. J. Chittleborough, School of Earth and Environmental Sciences, The University of Adelaide, North Terrace campus, Adelaide, South Australia 5001, Australia Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background and aims   Fruit orchards potential as carbon (C) sinks is virtually unknown. Moreover, despite their importance in the Mediterranean area, few data are available about the effect of the reduction in water availability on fruit tree productivity. Here we report the effect of two different irrigation regimes on net primary (NPP) and net ecosystem (NEP) productivities of an apple orchard in northern Italy in 2006. Methods   Trees productivity and heterotrophic soil respiration were estimated by inventory and root exclusion methods, while belowground allocation with a C mass-balance approach. Results   The NPP of the control (7.86 ± 0.25 Mg C ha -1 ; mean ± SE) was significantly greater than that of water stressed trees (6.53 ± 0.12 Mg C ha -1 ), and the ratio between above and below net primary productivity (ANPP/BNPP) was 1.88 and 0.98 respectively. However, the partitioning of ANPP and BNPP among aerial organs and among fine, coarse roots, and root litter was unaffected by the water regime. Although NEP was greater in the control than in stressed trees the C gain of the system after fruit removal (NEP afr ) was unaffected by water availability. Conclusions   This study indicated an effect of water availability on C partitioning patterns above- and belowground, although there were no significant effects on the C sink potential as NEP afr . Content Type Journal Article Category Regular Article Pages 1-13 DOI 10.1007/s11104-012-1235-2 Authors Pietro Panzacchi, Department of fruit trees and woody plants sciences, University of Bologna, Viale Fanin, 46, 40127 Bologna, Italy Giustino Tonon, Faculty of Science and Technology - Piazza Università, Free University of Bolzano/Bozen, 5, 39100 Bolzano-Bozen, Italy Christian Ceccon, Faculty of Science and Technology - Piazza Università, Free University of Bolzano/Bozen, 5, 39100 Bolzano-Bozen, Italy Francesca Scandellari, Faculty of Science and Technology - Piazza Università, Free University of Bolzano/Bozen, 5, 39100 Bolzano-Bozen, Italy Maurizio Ventura, Faculty of Science and Technology - Piazza Università, Free University of Bolzano/Bozen, 5, 39100 Bolzano-Bozen, Italy Marco Zibordi, Department of fruit trees and woody plants sciences, University of Bologna, Viale Fanin, 46, 40127 Bologna, Italy Massimo Tagliavini, Faculty of Science and Technology - Piazza Università, Free University of Bolzano/Bozen, 5, 39100 Bolzano-Bozen, Italy Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background and Aims   Understanding the impact of soil rhizobial populations and inoculant rhizobia in supplying sufficient nodulation is crucial to optimising N 2 fixation by legume crops. This study explored the impact of different rates of inoculant rhizobia and contrasting soil rhizobia on nodulation and N 2 fixation in faba bean ( Vicia faba L.). Methods   Faba beans were inoculated with one of seven rates of rhizobial inoculation, from no inoculant to 100 times the normal rate of inoculation, sown at two field sites, with or without soil rhizobia present, and their nodulation and N 2 fixation assessed. Results   At the site without soil rhizobia, inoculation increased nodule number and increased N 2 fixation from 21 to 129 kg shoot N ha −1 , while N 2 fixation increased from 132 to 218 kg shoot N ha −1 at the site with high background soil rhizobia. At the site without soil rhizobia, inoculation increased concentrations of shoot N from 14 to 24 mg g −1 , grain N from 32 to 45 mg g −1 , and grain yields by 1.0 Mg (metric tonne) ha −1 . Differences in nodulation influenced the contributions of fixed N to the system, which varied from the net removal of 20 kg N ha −1 from the system in the absence of rhizobia, to a net maximum input of 199 kg N ha −1 from legume shoot and root residues, after accounting for removal of N in grain harvest. Conclusions   The impact of inoculation and soil rhizobia strongly influenced grain yield, grain N concentration and the potential contributions of legume cropping to soil N fertility. In soil with resident rhizobia, N 2 fixation was improved only with the highest inoculation rate. Content Type Journal Article Category Regular Article Pages 1-12 DOI 10.1007/s11104-012-1393-2 Authors Matthew D. Denton, Department of Primary Industries, RMB 1145 Chiltern Valley Road, Rutherglen, VIC 3685, Australia David J. Pearce, Department of Primary Industries, RMB 1145 Chiltern Valley Road, Rutherglen, VIC 3685, Australia Mark B. Peoples, CSIRO Sustainable Agriculture National Research Flagship, CSIRO Plant Industry, PO Box 1600, Canberra, ACT 2601, Australia Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background   The need to enhance the sustainability of intensive agricultural systems is widely recognized One promising approach is to encourage beneficial services provided by soil microorganisms to decrease the inputs of fertilizers and pesticides. However, limited success of this approach in field applications raises questions as to how this might be best accomplished. Scope   We highlight connections between root exudates and the rhizosphere microbiome, and discuss the possibility of using plant exudation characteristics to selectively enhance beneficial microbial activities and microbiome characteristics. Gaps in our understanding and areas of research that are vital to our ability to more fully exploit the soil microbiome for agroecosystem productivity and sustainability are also discussed. Conclusion   This article outlines strategies for more effectively exploiting beneficial microbial services on agricultural systems, and cals attention to topics that require additional research. Content Type Journal Article Category Marschner Review Pages 1-13 DOI 10.1007/s11104-012-1361-x Authors Matthew G. Bakker, Center for Rhizosphere Biology, Colorado State University, Fort Collins, CO 80523-1173, USA Daniel K. Manter, Soil-Plant-Nutrient Research, USDA-ARS, Fort Collins, CO 80526, USA Amy M. Sheflin, Center for Rhizosphere Biology, Colorado State University, Fort Collins, CO 80523-1173, USA Tiffany L. Weir, Center for Rhizosphere Biology, Colorado State University, Fort Collins, CO 80523-1173, USA Jorge M. Vivanco, Center for Rhizosphere Biology, Colorado State University, Fort Collins, CO 80523-1173, USA Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: A response to “How red mangrove seedlings stand up: an answer for Cheeseman (2012)” Content Type Journal Article Category Letter Pages 1-2 DOI 10.1007/s11104-012-1410-5 Authors John M. Cheeseman, Department of Plant Biology, University of Illinois at Urbana-Champaign, 505 S Goodwin Ave, Urbana, IL 61801, USA Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background and aims   Winter cover crop cultivation during the fallow season has been strongly recommended in mono-rice paddy soil to improve soil quality, but its impact in increasing the greenhouse gases (GHGs) emissions during rice cultivation when applied as green manure has not been extensively studied. In order to recommend a preferable cover crop which can increase soil productivity and suppress GHG emission impact in paddy soil, the effect of winter cover crop addition on rice yield and total global warming potential (GWP) was studied during rice cultivation. Methods   Two cover crops (Chinese milk vetch, Astragalus sinicus L., hereafter vetch, and rye, Secale cerealis ) having different carbon/nitrogen (C/N) ratios were cultivated during the rice fallow season. The fresh above-ground biomasses of vetch [25 Mg fresh weight (FW) ha −1 , moisture content (MC) 86.9 %, C/N ratio 14.8] and rye (29 Mg rye FW ha −1 , MC 78.0 %, C/N ratio 64.3) were incorporated as green manure 1 week before rice transplanting (NPK + vetch, and NPK + rye). The NPK treatment was installed for comparison as the control. During the rice cultivation, methane (CH 4 ) and nitrous oxide (N 2 O) gases were collected simultaneously once a week using the closed-chamber method, and carbon dioxide (CO 2 ) flux was estimated using the soil C balance analysis. Total GWP impact was calculated as CO 2 equivalents by multiplying the seasonal CH 4 , CO 2 , and N 2 O fluxes by 25, 1, and 298, respectively. Results   Methane mainly covered 79–81 % of the total GWP, followed by CO 2 (14–17 %), but the N 2 O contribution was very small (2–5 %) regardless of the treatment. Seasonal CH 4 fluxes significantly increased to 61 and 122 % by vetch and rye additions, respectively, compared to that of the NPK treatment. Similarly, the estimated seasonal CO 2 fluxes increased at about 197 and 266 % in the vetch and rye treatments, respectively, compared with the NPK control plots. Based on these results, the total GWP increased to 163 and 221 % with vetch and rye applications, respectively, over the control treatment. Rice productivity was significantly increased with the application of green manure due to nutrient supply; however, vetch was more effective. Total GWP per grain yield was similar with the vetch (low C/N ratio) and NPK treatments, but significantly increased with the rye (high C/N ratio) application, mainly due to its higher CH 4 emission characteristic and lower rice productivity increase. Conclusions   A low C/N ratio cover crop, such as vetch, may be a more desirable green manure to reduce total GWP per grain yield and to improve rice productivity. Content Type Journal Article Category Regular Article Pages 1-14 DOI 10.1007/s11104-012-1403-4 Authors Sang Yoon Kim, Division of Applied Life Science (BK 21 Program), Gyeongsang National University, Jinju, 660-701 South Korea Chang Hoon Lee, Division of Applied Life Science (BK 21 Program), Gyeongsang National University, Jinju, 660-701 South Korea Jessie Gutierrez, Division of Applied Life Science (BK 21 Program), Gyeongsang National University, Jinju, 660-701 South Korea Pil Joo Kim, Division of Applied Life Science (BK 21 Program), Gyeongsang National University, Jinju, 660-701 South Korea Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: How red mangrove seedlings stand up: an answer for Cheeseman (2012) Content Type Journal Article Category Commentary Pages 1-4 DOI 10.1007/s11104-012-1400-7 Authors Jack B. Fisher, Department of Botany, University of British Columbia, 3526-6270 University Blvd, Vancouver, BC V6T 1Z4, Canada P. Barry Tomlinson, The Kampong, National Tropical Botanical Garden, 4013 Douglas Rd, Miami, FL 33133, USA Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background   Endophytic diazotrophic bacteria colonize several non-leguminous plants and promote plant growth. Different mechanisms are involved in bacteria-induced plant growth promotion, including biological nitrogen fixation (BNF), mineral solubilization, production of phytohormones, and pathogen biocontrol. Herbaspirillum seropedicae is a broad-host-range endophyte that colonizes sugarcane, rice, wheat, sorghum, and maize, and has been used as a biofertilizer. Contrasting results between greenhouse and field experiments have prompted efforts to improve the consistency of the plant response to microbial stimulation. Aims   The aim of this study was to evaluate the effect of the presence of humic substances on inoculation of maize ( Zea mays L.) with H. seropedicae . Methods   Two experiments were conducted: one in the greenhouse using sand and nutrient solution and the other a field trial in soil with low natural fertility and to which was applied N in the form of urea (50 kg ha −1 ). In the greenhouse, pre-emerging seeds were inoculated with a solution of H. seropedicae (10 9 cells mL −1 ) in the presence of humic substances isolated from vermicompost (10, 20, or 30 mg C L −1 ); in the field trial, bacteria combined with humate were added as a foliar spray (450 L ha −1 ). Results   At early stages (7 and 45 days old) in the greenhouse, the treatment activated plant metabolism including enhancement of plasma membrane H + -ATPase activity, alteration of sugar and N metabolism, and greater net photosynthesis. The number of viable bacterial cells was higher in root tissues when inoculation was in the presence of soluble humic substances. Foliar application of endophytic diazotrophic bacteria and humic substances increased maize grain production 65 % under field conditions. These results show a promising use of humic substances to improve the benefit of endophytic diazotrophic inoculation. Content Type Journal Article Category Regular Article Pages 1-14 DOI 10.1007/s11104-012-1382-5 Authors Luciano Pasqualoto Canellas, Núcleo de Desenvolvimento de Insumos Biológicos para a Agricultura (NUDIBA), Universidade Estadual do Norte Fluminense Darcy Ribeiro (UENF), Av. Alberto Lamego, 2000, Campos dos Goytacazes, 28013-602 Rio de Janeiro, Brazil Dariellys Martínez Balmori, Núcleo de Desenvolvimento de Insumos Biológicos para a Agricultura (NUDIBA), Universidade Estadual do Norte Fluminense Darcy Ribeiro (UENF), Av. Alberto Lamego, 2000, Campos dos Goytacazes, 28013-602 Rio de Janeiro, Brazil Leonardo Oliveira Médici, Departamento de Ciências Fisiológicas, Universidade Federal Rural do Rio de Janeiro, km7 BR 467, Seropédica, Rio de Janeiro, Brazil Natália Oliveira Aguiar, Núcleo de Desenvolvimento de Insumos Biológicos para a Agricultura (NUDIBA), Universidade Estadual do Norte Fluminense Darcy Ribeiro (UENF), Av. Alberto Lamego, 2000, Campos dos Goytacazes, 28013-602 Rio de Janeiro, Brazil Eliemar Campostrini, Laboratório de Melhoramento Genético Vegetal, Universidade Estadual do Norte Fluminense Darcy Ribeiro (UENF), Av. Alberto Lamego, 2000, Campos dos Goytacazes, 28013-602 Rio de Janeiro, Brazil Raul C. C. Rosa, Embrapa Mandioca e Fruticultura, Rua Embrapa, s/nº., CEP 44380-000 Cruz das Almas, BA, Brasil Arnoldo R. Façanha, Núcleo de Desenvolvimento de Insumos Biológicos para a Agricultura (NUDIBA), Universidade Estadual do Norte Fluminense Darcy Ribeiro (UENF), Av. Alberto Lamego, 2000, Campos dos Goytacazes, 28013-602 Rio de Janeiro, Brazil Fábio Lopes Olivares, Núcleo de Desenvolvimento de Insumos Biológicos para a Agricultura (NUDIBA), Universidade Estadual do Norte Fluminense Darcy Ribeiro (UENF), Av. Alberto Lamego, 2000, Campos dos Goytacazes, 28013-602 Rio de Janeiro, Brazil Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background and Aims   Explosives released into the environment from munitions production, processing facilities, or buried unexploded ordnances can be absorbed by surrounding roots and induce toxic effects in leaves and stems. Research into the mechanisms with which explosives disrupt physiological processes could provide methods for discrimination of anthropogenic and natural stresses. Our objectives were to experimentally evaluate the effects of natural stress and explosives on plant physiology and to link differences among treatments to changes in hyperspectral reflectance for possible remote detection. Methods   Photosynthesis, water relations, chlorophyll fluorescence, and hyperspectral reflectance were measured following four experimental treatments (drought, salinity, trinitrotoluene and hexahydro-1,3,5-trinitro-l,3,5-triazine) on two woody species. Principal Components Analyses of physiological and hyperspectral results were used to evaluate the differences among treatments. Results   Explosives induced different physiological responses compared to natural stress responses. Stomatal regulation over photosynthesis occurred due to natural stress, influencing energy dissipation pathways of excess light. Photosynthetic declines in explosives were likely the result of metabolic dysfunction. Select hyperspectral indices could discriminate natural stressors from explosives using changes in the red and near-infrared spectral region. Conclusions   These results show the possibility of using variations in energy dissipation and hyperspectral reflectance to detect plants exposed to explosives in a laboratory setting and are promising for field application using plants as phytosensors to detect explosives contamination in soil. Content Type Journal Article Category Regular Article Pages 1-9 DOI 10.1007/s11104-012-1414-1 Authors Julie C. Zinnert, US Army ERDC, Fluorescence Spectroscopy Lab, 7701 Telegraph Road, Alexandria, VA 22315, USA Stephen M. Via, Department of Biology, Virginia Commonwealth University, Richmond, VA 23284, USA Donald R Young, Department of Biology, Virginia Commonwealth University, Richmond, VA 23284, USA Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background and aims   Soil structure degradation by fire is usually attributed to qualitative and quantitative change of organic and inorganic binding agents, especially in high severity burns (〉300 °C) that last for prolonged periods (〉 1 hour). In contrast, controlled burns are typically managed to be low in intensity and severity. Such burns are considered benign to soil structural stability because organic matter and inorganic binding agents (e.g., gypsum) are relatively stable at such low temperatures. Recent observations at a controlled burn site in the eastern Great Basin (Nevada) showed soil aggregate breakdown found in shrub canopies where soil temperatures briefly exceeded 300 °C as well as interspaces between shrubs, where the temperatures were likely lower than beneath shrubs because of less surface biomass. These alterations cannot be explained in terms of thermal alteration of binding agents. This study was designed to test whether pressure created by rapidly vaporized pore water can cause aggregate breakdown. Methods   We subjected three different sizes of aggregates (0.25–1, 1–2 and 2–4 mm) of soils derived from the eastern Great Basin burn site as well as from a forest and urban garden in California to rapid and slow (3 °C/min) heating rates. These treatments were conducted at 5 peak temperatures (75, 100, 125, 150 and 175 °C). Results   Post-burn water stability of the aggregates showed that rapid heating rate caused more pronounced degradation of aggregate stability than slow heating. Moreover, the heating-rate dependent structural degradation increased with peak temperature. For the majority of the aggregates, the effect also increased with initial water content. In all the soils tested, there was no preferential loss of organic matter in the rapid-heating treatment that can explain the observed enhanced breakdown of aggregates. Conclusions   Our observations indicate that soil structural degradation under low-intensity fire occurs as a result of mechanical stresses extorted by rapidly escaping steam from soil pores under rapid heating rate. Content Type Journal Article Category Regular Article Pages 1-10 DOI 10.1007/s11104-012-1408-z Authors Ammar A. Albalasmeh, University of California, Merced, Merced, CA, USA Markus Berli, Desert Research Institute, University of Nevada System, Reno, NV, USA David S. Shafer, Desert Research Institute, University of Nevada System, Reno, NV, USA Teamrat A. Ghezzehei, University of California, Merced, Merced, CA, USA Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background and aims   Rare Earth Elements (REE) are widely used to trace natural geochemical processes. They are also increasingly used by man (electronics industry, medicine, agriculture) and therefore considered as emerging pollutants. The present study documents REE mobility in non-polluted natural soil-plant systems in order to characterize their environmental availability for future anthropogenic pollution. Methods   The study is based on a field approach in non-polluted natural sites with contrasting geological environments (limestone, granite, and carbonatite) and highly variable REE contents. Results   REE concentrations in soils do not directly reflect bedrock concentrations, but depend largely on pedogenetic processes and on the mineralogy of bedrock and soil. The soils of all sites are with respect to bedrock enriched in heavy REE. The REE uptake by plants is not primarily controlled by the plant itself, but depends on the concentration and the speciation in the soil and the adsorbed soil water pool. Conclusions   REE uptake by plant roots are linked with those of Fe. Roots absorb preferentially the light REE. Before translocation, REE are retained by the Casparian strip leading to much lower concentrations in the aerial parts. The transport of the REE within the xylem is associated with the general nutrient flux. Content Type Journal Article Category Regular Article Pages 1-21 DOI 10.1007/s11104-012-1407-0 Authors L. Brioschi, UMR CNRS 6249 Chrono-Environnement, Université de Franche-Comté, 25030 Besançon, France M. Steinmann, UMR CNRS 6249 Chrono-Environnement, Université de Franche-Comté, 25030 Besançon, France E. Lucot, UMR CNRS 6249 Chrono-Environnement, Université de Franche-Comté, 25030 Besançon, France M. C. Pierret, UMR CNRS 7517 LHyGeS-EOST, Université de Strasbourg, 67084 Strasbourg, France P. Stille, UMR CNRS 7517 LHyGeS-EOST, Université de Strasbourg, 67084 Strasbourg, France J. Prunier, UMR CNRS 7517 LHyGeS-EOST, Université de Strasbourg, 67084 Strasbourg, France P. M. Badot, UMR CNRS 6249 Chrono-Environnement, Université de Franche-Comté, 25030 Besançon, France Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background and aims   Forest management activities influences stand nutrient budgets, belowground carbon allocation and storage in the soil. A field experiment was carried out in Southern Ethiopia to investigate the effect of thinning on fine root dynamics and associated soil carbon accretion of 6-year old C. lusitanica stands. Methods   Fine roots (≤2 mm in diameter) were sampled seasonally to a depth of 40 cm using sequential root coring method. Fine root biomass and necromass, vertical distribution, seasonal dynamics, annual turnover and soil carbon accretion were quantified. Results   Fine root biomass and necromass showed vertical and temporal variations. More than 70 % of the fine root mass was concentrated in the top 20 cm soil depth. Fine root biomass showed significant seasonal variation with peaks at the end of the major rainy season and short rainy season. Thinning significantly increased fine root necromass, annual fine root production and turnover. Mean annual soil carbon accretion, through fine root necromass, in the thinned stand was 63 % higher than that in the un-thinned stand. Conclusions   The temporal dynamics in fine roots is driven by the seasonality in precipitation. Thinning of C. lusitanica plantation would increase soil C accretion considerably through increased fine root necromass and turnover. Content Type Journal Article Category Regular Article Pages 1-11 DOI 10.1007/s11104-012-1420-3 Authors Zeleke Asaye, Oromiya Agricultural Research Institute, Ziway, Ethiopia Solomon Zewdie, School of Forestry, Wondo Genet College of Forestry and Natural Resources, Hawassa University, P. O. Box 128, Hawassa, Ethiopia Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Aims   Chickpea ( Cicer arietinum L.) is considered a salt sensitive species, but some genetic variation for salinity tolerance exists. The present study was initiated to determine the degree of salt tolerance among chickpea genotypes, and the relationship between salt tolerance and ion accumulation in leaves and reproductive tissues. Methods   Three experiments were conducted in a glasshouse in Perth, Western Australia, in which up to 55 genotypes of chickpea were subjected to 0, 40 or 60  mM NaCl added to the soil to determine the variation in salt tolerance, and the association between salt tolerance and reproductive success. Pod and seed numbers, seed yield and yield components, pollen viability, in vitro pollen germination and in vivo pollen tube growth, were used to evaluate reproductive success. Leaves, flowers and seeds were sampled in the reproductive phase to measure the concentrations of sodium, potassium and chloride ions in these organs. Results   When grown in soil with 40  mM NaCl, a 27-fold range in seed yield was observed among the 55 chickpea genotypes. The increased salt tolerance, as measured by yield under salinity or relative yield under saline conditions, was positively associated with higher pod and seed numbers, and higher shoot biomass, but not with time to 50 % flowering nor with the number of filled pods in the non-saline treatment. Pod abortion was higher in the salt sensitive genotypes, but pollen viability, in vitro pollen germination and in vivo pollen tube growth were not affected by salinity in either the salt tolerant or salt sensitive genotypes. The concentrations of sodium and potassium ions, but not chloride, in the seed were significantly higher in the sensitive (106 μmol g −1 DM of sodium and 364 μmol g −1 DM of potassium) than in the tolerant (74 and 303 μmol g −1 DM, respectively) genotypes. Sodium and potassium, but particularly chloride, ions accumulated in leaves and in pod wall, whereas accumulation in the seed was much lower. Conclusions   Considerable genotypic variation for salt tolerance exists in chickpea germplasm. Selection for genotypes with high pod and/or seed numbers that accumulate low concentrations of salt in the seed will be beneficial. Content Type Journal Article Category Regular Article Pages 1-15 DOI 10.1007/s11104-012-1387-0 Authors Neil C. Turner, Centre for Legumes in Mediterranean Agriculture, M080, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia Timothy D. Colmer, Centre for Legumes in Mediterranean Agriculture, M080, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia John Quealy, Centre for Legumes in Mediterranean Agriculture, M080, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia R. Pushpavalli, International Crops Research Institute for the Semi-Arid Tropics, Patancheru, Andhra Pradesh 502 234, India L. Krishnamurthy, International Crops Research Institute for the Semi-Arid Tropics, Patancheru, Andhra Pradesh 502 234, India Jagmeet Kaur, Department of Plant Breeding and Genetics, Punjab Agricultural University, Ludhiana, Punjab 141004, India Guriqbal Singh, Department of Plant Breeding and Genetics, Punjab Agricultural University, Ludhiana, Punjab 141004, India Kadambot H. M. Siddique, The UWA Institute of Agriculture, M082, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia Vincent Vadez, International Crops Research Institute for the Semi-Arid Tropics, Patancheru, Andhra Pradesh 502 234, India Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background and Aim   We hypothesised that amending an acidic ferralsol with biochar would improve the productivity of a subtropical dairy pasture via reducing soil acidity related constraints and result in improved nitrogen use efficiency. We examined two contrasting biochars with different carbon, nutrient content and acid neutralising values. Methods   Field plots were amended with one of three biochar treatments (Nil, feedlot manure biochar [FM], green waste biochar [GW]) in combination with presence or absence of NPK fertiliser and presence or absence of liming. The FM and GW biochars had a carbon content of 44 and 76 %, available phosphorous of 5,960 and 93 mg kg −1 , and liming values of 13 and 5.6 %, respectively. The pasture was managed to supply year round high quality feed for dairy production. Results   The FM biochar increased total pasture productivity by 11 % and improved the agronomic nitrogen use efficiency by 23 %. It also reduced soil acidity but did not significantly affect the pH dependent soil cation exchange capacity. The GW biochar did not improve pasture productivity. Both biochars resulted in an increase in the soil carbon density. Conclusions   The high available phosphorous content of FM biochar makes it an effective amendment for acidic ferralsols. Greenwaste biochar did not have sufficient acid neutralising capacity or phosphorous content to reduce soil acidity constraints. Both biochars enhance soil carbon storage in pasture systems on ferralsol. Content Type Journal Article Category Regular Article Pages 1-15 DOI 10.1007/s11104-012-1412-3 Authors P. G. Slavich, New South Wales Department of Primary Industries, Wollongbar, NSW 2477, Australia K. Sinclair, New South Wales Department of Primary Industries, Wollongbar, NSW 2477, Australia S. G. Morris, New South Wales Department of Primary Industries, Wollongbar, NSW 2477, Australia S. W. L. Kimber, New South Wales Department of Primary Industries, Wollongbar, NSW 2477, Australia A. Downie, Pacific Pyrolysis P/L, Somersby, NSW 2250, Australia L. Van Zwieten, New South Wales Department of Primary Industries, Wollongbar, NSW 2477, Australia Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background   Recent studies have questioned the validity of the mutualism-parasitism continuum of mycorrhizal function. This paper re-evaluates the continuum model and analyzes these concerns. Scope and Conclusions   Three insights arise from this analysis. First, the continuum model defines mycorrhizal function as an emergent property of complex interactions. The model identifies resource trade and symbiotic control as key determinants of the costs and benefits of the symbiosis for plants and fungi, and the interaction of these factors with the environment ultimately controls mycorrhizal function. Second, analysis of carbon costs and phosphorus benefits is too narrow a focus to accurately predict mycorrhizal function. Analysis of plant and fungal fitness responses in ecologically and evolutionarily relevant systems are required to elucidate the full range of nutritional and non-nutritional factors embodied within mycorrhizal functioning. Finally, the definition of the term ‘parasitism’ has evolved. Some fields of science maintain the original definition of a nutritional relationship between host and parasite while other fields define it as a +/- fitness relationship. This has generated debate about whether the continuum of mycorrhizal functioning should properly be called a positive–negative response continuum or a mutualism-parasitism continuum. This controversy about semantics should be resolved, but it does not overturn the continuum concept. Content Type Journal Article Category Review Article Pages 1-9 DOI 10.1007/s11104-012-1406-1 Authors Nancy Collins Johnson, School of Earth Sciences and Environmental Sustainability, Northern Arizona University, PO Box 5694, Flagstaff, AZ 86011, USA James H. Graham, Citrus Research and Education Center, University of Florida, Lake Alfred, FL 33850, USA Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background and aims   Acacia cyclops is an invasive species within Mediterranean ecosystems, characteristically low in soil nutrients. Thus associations with nitrogen-fixing bacteria (NFB) and arbuscular mycorrhiza (AM) may provide an advantage to these legumes. This study investigated the role of AM and NFB in the growth and nutritional physiology of A. cyclops . Methods   Seedlings were inoculated with naturally occurring NFB, Glomus mosseae or both, and grown under glasshouse conditions for 5 months. Plants were cultivated in sand and supplied with a 20 % strength nutrient solution. Xylem sap nutrients, photosynthetic rates, biomass and chemical compositions, were recorded. Results   The dual inoculation decreased the colonization of both symbionts, compared to a single symbiosis with either symbiont. Despite low colonization levels, the dual symbiosis increased host biomass and relative growth rates. This was associated with increased photosynthetic rates and enhanced nutrition. Additionally, dual symbiotic plants had enhanced N and P acquisition and utilization rates. Xylem sap analysis showed higher levels of NH 4 + being exported from the roots to the shoots in the dual symbiotic plants compared with other treatments. Conclusions   These findings suggest the dual symbiosis is an important factor in the growth and development of A. cyclops under nutrient limiting conditions. Content Type Journal Article Category Regular Article Pages 1-13 DOI 10.1007/s11104-012-1421-2 Authors Peter E. Mortimer, Key Laboratory of Biodiversity and Biogeography, Kunming Institute of Botany, Chinese Academy of Sciences, 132 Lanhei Road, Kunming, 650201 China Marcellous R. Le Roux, Botany and Zoology Department, University of Stellenbosch, Private Bag X1, Matieland, 7602 South Africa Maria A. Pérez-Fernández, Area de Ecología, Facultad de Ciencias Experimentales, University Pablo de Olavide, Cartera a Utrera, Km 1, 41013 Seville, Spain Vagner A. Benedito, Genetics and Developmental Biology Program, Division of Plant and Soil Sciences, West Virginia University, 1090 Agricultural Science Building, Morgantown, WV 26506, USA Aleysia Kleinert, Botany and Zoology Department, University of Stellenbosch, Private Bag X1, Matieland, 7602 South Africa Jianchu Xu, World Agroforestry Centre, East Asia, 132 Lanhei Road, Kunming, 650201 China Alexander J. Valentine, Botany and Zoology Department, University of Stellenbosch, Private Bag X1, Matieland, 7602 South Africa Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Aims   Wilderness and other natural areas are threatened by large-scale disturbances (e.g., wildfire), air pollution, climate change, exotic diseases or pests, and a combination of these stress factors (i.e., stress complexes). Linville Gorge Wilderness (LGW) is one example of a high elevation wilderness in the southern Appalachian region that has been subject to stress complexes including chronic acidic deposition and several wildfires, varying in intensity and extent. Soils in LGW are inherently acidic with low base cation concentrations and decades of acidic deposition have contributed to low pH, based saturation, and Ca:Al ratio. We hypothesized that wildfires that occurred in LGW followed by liming burned areas would accelerate the restoration of acidic, nutrient depleted soils. Because soils at LGW had extremely low concentrations of exchangeable Ca 2+ and Mg 2+ dolomitic lime was applied to further boost these cations. We evaluated the effectiveness of dolomitic lime application in restoring exchangeable Ca 2+ and Mg 2+ and subsequently increasing pH and Ca:Al ratio of soils and making Ca and Mg available to recovering vegetation. Methods   Five treatment areas were established: severely burned twice (2000 & 2007) with dolomitic lime application (2xSBL); moderately burned twice with lime application (2xMBL); severely burned twice, unlimed (2xSB); moderately burned once (2000), unlimed (1xMB); and a reference area (REF; unburned, unlimed). In 2008 and 2009, we measured overstory, understory, and ground-layer vegetation; forest floor mass and nutrients; and soil and soil solution chemistry within each treatment area. Results   All wildfire burned sites experienced substantial overstory mortality. However, understory biomass doubled between sample years on the most recently burned sites due to the rapid regrowth of ericaceous shrubs and prolific sprouting of deciduous trees. Burning followed by lime application (2xSBL and 2xMBL) significantly increased shallow soil solution NO 3 -N, but we found no soil solution NO 3 -N response to burning alone (2xSB and 1xMB). Surface soil base saturation and exchangeable Ca 2+ were significantly affected by liming; Ca 2+ concentrations were greater on 2xMBL and 2xSBL than 2xSB, 1xMB and REF. There was a smaller difference due to moderate burning along with greater soil Ca 2+ on 1xMB compared to REF, but no difference between 2xSB and REF. Surface and subsurface soil exchangeable Al 3+ were lower on 2xSBL than 2xSB, 2xMBL, 1xMB, and REF. Liming decreased soil acidity somewhat as surface soil pH was higher on the two burned sites with lime (pH = 3.8) compared to 2xSB without lime (pH = 3.6). Conclusions   Liming resulted in decreased soil Al 3+ on 2xSBL coupled with increased soil Ca 2+ on both 2xSBL and 2xMBL, which improved soil Ca/Al ratios. However, the soil Ca/Al ratio response was transitory, as exchangeable Al 3+ increased and Ca/Al ratio decreased over time. Higher lime application rates may be necessary to obtain a substantial and longer-term improvement of cation-depleted soils at LGW. Content Type Journal Article Category Regular Article Pages 1-19 DOI 10.1007/s11104-012-1416-z Authors Katherine J. Elliott, USDA Forest Service, Southern Research Station, Center for Forest Watershed Science, Coweeta Hydrologic Laboratory, Otto, NC 28763, USA Jennifer D. Knoepp, USDA Forest Service, Southern Research Station, Center for Forest Watershed Science, Coweeta Hydrologic Laboratory, Otto, NC 28763, USA James M. Vose, USDA Forest Service, Southern Research Station, Center for Integrated Forest Science and Synthesis, Raleigh, NC 27607, USA William A. Jackson, USDA Forest Service, Region 8, National Forests of North Carolina, Air Resources Program, Asheville, NC 28804, USA Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Aims   The ability to suppress soil nitrification through the release of nitrification inhibitors from plant roots is termed ‘biological nitrification inhibition’ (BNI). Here, we aimed at the quantification and characterization of the BNI function in sorghum that includes inhibitor production, their chemical identity, functionality and factors regulating their release. Methods   Sorghum was grown in solution culture and root exudate was collected using aerated NH 4 Cl solutions. A bioluminescence assay using recombinant Nitrosomonas europaea was employed to determine the BNI activity. Activity-guided chromatographic fractionation was used to isolate biological nitrification inhibitors (BNIs). The chemical structure was analyzed using NMR and mass spectrometry; pH-stat systems were deployed to analyze the role of rhizosphere pH on BNIs release. Results   Sorghum roots released two categories of BNIs: hydrophilic- and hydrophobic-BNIs. The release rates for hydrophilic- and hydrophobic- BNIs ranged from 10 to 25 ATU g −1 root dwt. d −1 . Addition of hydrophilic BNIs (10 ATU g −1 soil) significantly inhibited soil nitrification (40 % inhibition) during a 30-d incubation test. Two BNI compounds isolated are: sakuranetin (ED 80 0.6 μM; isolated from hydrophilic-BNIs fraction) and sorgoleone (ED 80 13.0 μM; isolated from hydrophobic-BNIs fraction), which inhibited Nitrosomonas by blocking AMO and HAO enzymatic pathways. The BNIs release required the presence of NH 4 + in the root environment and the stimulatory effect of NH 4 + lasted 24 h. Unlike the hydrophobic-BNIs, the release of hydrophilic-BNIs declined at a rhizosphere pH 〉5.0; nearly 80 % of hydrophilic-BNI release was suppressed at pH ≥7.0. The released hydrophilic-BNIs were functionally stable within a pH range of 5.0 to 9.0. Sakuranetin showed a stronger inhibitory activity (ED 50 0.2 μM) than methyl 3-(4-hydroxyphenyl) propionate (MHPP) (ED 50 100 μM) (isolated from hydrophilic-BNIs fraction) in the in vitro culture-bioassay, but the activity was non-functional and ineffective in the soil-assay. Conclusions   There is an urgent need to identify sorghum genetic stocks with high potential to release functional-BNIs for suppressing nitrification and to improve nitrogen use efficiency in sorghum-based production systems. Content Type Journal Article Category Regular Article Pages 1-17 DOI 10.1007/s11104-012-1419-9 Authors G. V. Subbarao, Crop, Livestock and Environment Division, Japan International Research Center for Agricultural Sciences (JIRCAS), 1-1 Ohwashi, Tsukuba, Ibaraki 305 0035, Japan K. Nakahara, Crop, Livestock and Environment Division, Japan International Research Center for Agricultural Sciences (JIRCAS), 1-1 Ohwashi, Tsukuba, Ibaraki 305 0035, Japan T. Ishikawa, Crop, Livestock and Environment Division, Japan International Research Center for Agricultural Sciences (JIRCAS), 1-1 Ohwashi, Tsukuba, Ibaraki 305 0035, Japan H. Ono, National Food Research Institute, National Agriculture and Food Research Organization, Tsukuba, Ibaraki 305-8642, Japan M. Yoshida, National Food Research Institute, National Agriculture and Food Research Organization, Tsukuba, Ibaraki 305-8642, Japan T. Yoshihashi, Crop, Livestock and Environment Division, Japan International Research Center for Agricultural Sciences (JIRCAS), 1-1 Ohwashi, Tsukuba, Ibaraki 305 0035, Japan Yiyong Zhu, Department of Plant Nutrition, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, 210095 China H. A. K. M. Zakir, Department of Crop Botany, Bangladesh Agricultural University, Mymensingh, 2002 Bangladesh S. P. Deshpande, International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru, Hyderabad, 502 324 Andhra Pradesh, India C. T. Hash, International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru, Hyderabad, 502 324 Andhra Pradesh, India K. L. Sahrawat, International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru, Hyderabad, 502 324 Andhra Pradesh, India Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background and Aims   Crop residues are important for the redistribution of alkalinity within soils. A net increase in pH following residue addition to soil is typically reported. However, effects are inconsistent in the field due to confounding soil processes and agronomic practises. Methods   A column experiment investigated the effects of canola, chickpea and wheat residues, differing in alkalinity content and C:N ratio, on soil pH changes in a Podosol (Podzol; initial pH 4.5) and Tenosol (Cambisol; initial pH 6.2) under field conditions. Results   Residues (10 g dry matter kg -1 soil; 0–10 cm) increased soil pH, and temporal changes in alkalinity depended on the residue and soil type. Alkalinity was generated via abiotic association reactions between H + and added organic matter and via ammonification and decarboxylation processes during decomposition. Alkalinity from canola and chickpea residues moved down the soil profile (10–30 cm) and was attributed to nitrate immobilisation and organic anion decomposition by soil microbes. Conclusions   The application of residues to acid and moderately acid soils increased the pH of both topsoil and subsoils, which persisted over 26 months. Maximal increase of pH observed at 3 months was correlated with the concentration of excess cations in the residues. Content Type Journal Article Category Regular Article Pages 1-14 DOI 10.1007/s11104-012-1422-1 Authors C. R. Butterly, Department of Agricultural Sciences, LaTrobe University, Melbourne Campus, Bundoora, Victoria 3086, Australia J. A. Baldock, CSIRO Sustainable Agriculture Flagship, CSIRO Land and Water, PMB 2, Glen Osmond, South Australia 5064, Australia C. Tang, Department of Agricultural Sciences, LaTrobe University, Melbourne Campus, Bundoora, Victoria 3086, Australia Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background and aims   Al tolerance is one of the most important trait for worldwide crop production. Using microarrays, we previously identified a transcription factor belonging to the C2H2 zinc finger protein (ZFP) family associated with Al tolerance in wheat (Houde and Diallo, BMC Genomics 9:400, 2008 ). The current work aimed to identify specific members of the C2H2 ZFP family that are associated with Al tolerance. Methods   Wheat ESTs were used to assemble C2H2 ZFP family members that do not contain a classical EAR repressor domain. Specific primers were designed for qRT-PCR expression profiling of wheat root tips exposed to Al and H 2 O 2. Two Al-tolerant and sensitive wheat cultivars including a pair of near-isogenic lines differing in Al tolerance were used. Results   We reconstituted 16 wheat Q-type C2H2 ZFP. Expression profiling identified two transcripts ( TaZFP2 and TaZFP3 ) that accumulate rapidly upon exposure to Al or in response to H 2 O 2 in two tolerant wheat cultivars, including the tolerant near-isogenic line. Conclusion   The responsiveness of these transcripts to H 2 O 2 suggests that they may represent the wheat orthologs of ZFP transcription factors ZAT7 and ZAT12 that were shown to improve ROS tolerance in Arabidopsis . Thus, they may play a crucial role in the improvement of oxidative stress tolerance in wheat. Content Type Journal Article Category Regular Article Pages 1-14 DOI 10.1007/s11104-012-1417-y Authors Mohamed Ali Ali-Benali, Centre TOXEN, Département des Sciences biologiques, Université du Québec à Montréal, C.P. 8888, Succ. Centre-ville, Montréal, QC, Canada H3C 3P8 Mohamed Badawi, Centre TOXEN, Département des Sciences biologiques, Université du Québec à Montréal, C.P. 8888, Succ. Centre-ville, Montréal, QC, Canada H3C 3P8 Yoan Houde, Centre TOXEN, Département des Sciences biologiques, Université du Québec à Montréal, C.P. 8888, Succ. Centre-ville, Montréal, QC, Canada H3C 3P8 Mario Houde, Centre TOXEN, Département des Sciences biologiques, Université du Québec à Montréal, C.P. 8888, Succ. Centre-ville, Montréal, QC, Canada H3C 3P8 Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background and aims   Biochar is produced from the pyrolysis of organic materials, and when buried in soil can act as a long term soil carbon (C) store. Evidence suggests that biochar can also increase crop yields, reduce nutrient leaching and increase biological nitrogen fixation in leguminous plants. However, the potential for increasing biological N 2 fixation in agroecosystems is poorly understood, with inconsistent reports of root nodulation following biochar application. Therefore, the aim of this study was to determine the effect of biochar application rate and time since application on nodulation and nitrogenase activity in nodules of clover grown in a temperate agricultural soil. Methods   We used replicated field plots with three biochar application rates (0, 25 and 50 t ha −1 ). Three years after biochar amendment, the plots were further split and fresh biochar added at two different rates (25 and 50 t ha −1 ) resulting in double-loaded reapplications of 25 + 25 and 50 + 50 t ha −1 . Results   Three years after biochar application, there was no significant difference in the total number of root nodules between biochar-amended and unamended soil, regardless of the application rate. However, despite clover root nodules being of a similar number and size the level of nitrogenase activity of individual nodules in biochar-amended soil was significantly higher than in unamended soil. Reapplication of biochar resulted in decreased nodulation, although the rate of nitrogenase activity per nodule remained unaffected. Conclusion   In the short term, biochar influences root nodule number and localised N 2 fixation per nodule; however, total nitrogenase activity for the whole root system remained unaffected by the application rate of biochar or time since its application. These results emphasise the importance of long-term field studies, with a variety of applications rates for determining the influence of biochar applications on N 2 -fixing organisms and in providing data that can meaningfully inform agronomic management decisions and climate change mitigation strategies. Content Type Journal Article Category Regular Article Pages 1-10 DOI 10.1007/s11104-012-1411-4 Authors Richard S. Quilliam, School of Environment, Natural Resources & Geography, Bangor University, Bangor, Gwynedd, LL57 2UW UK Thomas H. DeLuca, School of Environment, Natural Resources & Geography, Bangor University, Bangor, Gwynedd, LL57 2UW UK Davey L. Jones, School of Environment, Natural Resources & Geography, Bangor University, Bangor, Gwynedd, LL57 2UW UK Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Aims and background   The DGT test is an emerging soil test to measure available phosphorus (P) in soils. Data from previous pot and field trials suggested a superior predictive power of this test relative to established soil P tests. Modeling also predicted that the critical DGT value (to obtain 80 % of the maximum yield) is plant specific. This study was set-up to test the DGT relative to established soil P tests in predicting the growth response to P addition across different tropical soils marked by P deficiency, for two plants with contrasting P demand. Methods   Maize ( Zea mays L.) and upland rice ( Oryza sativa L.) were grown in a greenhouse on 9 contrasting soils that were amended with P at increasing doses. Soil tests were measured on incubated soils for all P treatments. Results   Shoot dry weight increased with increasing P application by factors 2 to 90. The P doses required to reach 80 % of maximum dry weight or yield ranged from 20 to 580 mg P kg −1 and were always larger for the faster growing maize than for rice. The DGT method and CaCl 2 extractions explained relative yield of maize among soils better (R² = 0.84 and 0.69 respectively) than P determined by Olsen, Colwell, Bray-1, Mehlich-3, ammonium oxalate and resin extractions (R² 〈 0.53). In strong contrast, relative yields of rice were best predicted by Mehlich-3, Bray-1, Olsen and resin P (R² ~ 0.7) compared to DGT (R² = 0.59) and CaCl 2 (R² = 0.12). The DGT P concentration in a soil to obtain 80 % of maximum growth, i.e. the critical DGT values, were 73 μg P L −1 (maize) and 7 μg P L −1 (rice). The critical DGT value measured for maize is in correspondence with literature. Conclusions   For tropical P deficient soils, intensity based indices of soil P availability such as DGT and CaCl 2 , are superior to quantity based indices (i.e. the established soil P tests based on extraction) for maize with high P demand. However, the reverse is true for rice suggesting that diffusion of P in the soil as measured by DGT is not the main factor explaining P uptake for rice. Content Type Journal Article Category Regular Article Pages 1-18 DOI 10.1007/s11104-012-1375-4 Authors Laetitia Six, Department of Earth and Environmental Sciences, Division of Soil and Water Management, KU Leuven, Kasteelpark Arenberg 20, 3001 Heverlee, Belgium Erik Smolders, Department of Earth and Environmental Sciences, Division of Soil and Water Management, KU Leuven, Kasteelpark Arenberg 20, 3001 Heverlee, Belgium Roel Merckx, Department of Earth and Environmental Sciences, Division of Soil and Water Management, KU Leuven, Kasteelpark Arenberg 20, 3001 Heverlee, Belgium Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Aims   Although many studies on the mechanism of Al toxicity and tolerance have been conducted independently, events occurring during the recovery process from Al injury is limited. This study was to investigate Al toxicity recovery mechanism focusing in morphological and physiological aspect. Methods   We investigated the mechanisms underlying Al toxicity recovery in terms of oxidative stress using the pea root apex as a model system. Results   The accumulation of reactive oxygen species was remarkably high in the root under continued Al treatment but decreased in the recovering root. The superoxide anion exuded in the presence of nicotinamide adenine dinucleotide phosphate (NADPH) showed a similar tendency with respect to the accumulation of reactive oxygen species. A similar pattern of lignin content and superoxide dismutase activity was observed among the treatments, while the increased peroxidation in the root under continued Al treatment did not decline with recovery treatment. A longitudinal section of the root under continued Al treatment showed the accumulation of superoxide anion, lignin and peroxide (H 2 O 2 ) at the epidermal and outer cortex region where the Al induced injuries, including ruptures, are detected. Conclusions   Oxidative stress is associated with the mechanism of Al toxicity recovery. The recovery process might include the elongation of the central cylinder as a consequence of the oxidative stress-induced formation of the zonal region (ZR). The results further suggest a plausible role for the ZR in the programmed cell death-like function involved in Al toxicity recovery. Content Type Journal Article Category Regular Article Pages 1-12 DOI 10.1007/s11104-012-1396-z Authors Hideaki Matsumoto, Research Institute of Health and Welfare, KIBI International University, 8 Iga-machi, Takahashi-city, Okayama 716-8508, Japan Hirotoshi Motoda, Research Institute of Health and Welfare, KIBI International University, 8 Iga-machi, Takahashi-city, Okayama 716-8508, Japan Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background and Aims   Field studies have demonstrated that aluminum (Al) toxicity is low in no-till systems during cropping seasons that have adequate and well-distributed rainfall. This study evaluated the performance of corn ( Zea mays L.) and soybean ( Glycine max L. Merrill) on an acid loamy soil under a long-term no-till system, in response to surface liming and as affected by genotypic tolerance to Al and water stress. Methods   A field trial examined the effect of surface application of lime (0, 4, 8, and 12 Mg ha −1 ) on no-till corn and soybean nutrition and yield. Trials were also carried out in undisturbed soil columns taken from the unlimed and limed plots. Two hybrids/cultivars of corn and soybean, one sensitive and the other moderately sensitive to Al were grown at two soil moisture levels with and without water stress (50 % and 80 % water filled pore space). Results   Alleviating soil acidity by liming improved nutrition and increased grain yields of corn and soybean. The benefits of liming on root length density, nutrient uptake and shoot biomass production of corn and soybean were more pronounced in Al-sensitive genotypes under water stress. Conclusions   The results suggest that plants exposed to drought stress under no-till systems are more affected by Al toxicity. Content Type Journal Article Category Regular Article Pages 1-16 DOI 10.1007/s11104-012-1413-2 Authors Helio Antonio Wood Joris, Instituto Agronômico de Campinas (IAC), Av. Barão de Itapura, 1481, Campinas, 13012-970 São Paulo, Brazil Eduardo Fávero Caires, Department of Soil Science and Agricultural Engineering, Universidade Estadual de Ponta Grossa (UEPG), Av. Gen. Carlos Cavalvanti, 4748, Ponta Grossa, 84030-900 Paraná, Brazil Angelo Rafael Bini, Department of Soil Science and Agricultural Engineering, Universidade Estadual de Ponta Grossa (UEPG), Av. Gen. Carlos Cavalvanti, 4748, Ponta Grossa, 84030-900 Paraná, Brazil Danilo Augusto Scharr, Department of Soil Science and Agricultural Engineering, Universidade Estadual de Ponta Grossa (UEPG), Av. Gen. Carlos Cavalvanti, 4748, Ponta Grossa, 84030-900 Paraná, Brazil Adriano Haliski, Department of Soil Science and Agricultural Engineering, Universidade Estadual de Ponta Grossa (UEPG), Av. Gen. Carlos Cavalvanti, 4748, Ponta Grossa, 84030-900 Paraná, Brazil Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Rhizosphere 3: where plants meet soils down-under Content Type Journal Article Category Editorial Pages 1-5 DOI 10.1007/s11104-012-1415-0 Authors Mark Tibbett, National Soil Resources Institute, Department of Environmental Sciences and Technology, School of Applied Sciences, Cranfield University, Cranfield, Bedfordshire MK43 0AL, UK Megan Ryan, School of Plant Biology and Institute of Agriculture, The University of Western Australia, Crawley, WA 6009, Australia Michael A. Kertesz, Faculty of Agriculture and Environment, University of Sydney, Sydney, NSW 2006, Australia Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Aims   Biological soil crusts (BSCs), composed of mosses, lichens, liverworts and cyanobacteria, are a key component of arid and semi-arid ecosystems worldwide, and play key roles modulating several aspects of the nitrogen (N) cycle, such as N fixation and mineralization. While the performance of its constituent organisms largely depends on moisture and rainfall conditions, the influence of these environmental factors on N transformations under BSC soils has not been evaluated before. Methods   The study was done using soils collected from areas devoid of vascular plants with and without lichen-dominated BSCs from a semi-arid Stipa tenacissima grassland. Soil samples were incubated under different temperature (T) and soil water content (SWC) conditions, and changes in microbial biomass-N, dissolved organic nitrogen (DON), amino acids, ammonium, nitrate and both inorganic N were monitored. To evaluate how BSCs modulate the resistance of the soil to changes in T and SWC, we estimated the Orwin and Wardle Resistance index. Results   The different variables studied were more affected by changes in T than by variations in SWC at both BSC-dominated and bare ground soils. However, under BSCs, a change in the dominance of N processes from a net nitrification to a net ammonification was observed at the highest SWC, regardless of T. Conclusions   Our results suggest that the N cycle is more resistant to changes in T in BSC-dominated than in bare ground areas. They also indicate that BSCs could play a key role in minimizing the likely impacts of climate change on the dynamics of N in semi-arid environments, given the prevalence and cover of these organisms worldwide. Content Type Journal Article Category Regular Article Pages 1-13 DOI 10.1007/s11104-012-1404-3 Authors Manuel Delgado-Baquerizo, Departamento de Sistemas Físicos, Químicos y Naturales, Universidad Pablo de Olavide, Carretera de Utrera km. 1, 41013 Sevilla, Spain Fernando T. Maestre, Área de Biodiversidad y Conservación, Departamento de Biología y Geología, Escuela Superior de Ciencias Experimentales y Tecnología, Universidad Rey Juan Carlos, c/Tulipán s/n, 28933 Móstoles, Spain Antonio Gallardo, Departamento de Sistemas Físicos, Químicos y Naturales, Universidad Pablo de Olavide, Carretera de Utrera km. 1, 41013 Sevilla, Spain Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background and aims   DNA-based methods present new opportunities for overcoming the difficulties of accurately identifying and quantifying roots of different plant species in field soils. In order to quantify species-specific root biomass from measurements of DNA, consideration needs to be given to replication and ability to recover roots for calibration purposes in order to account for spatial, temporal and inter- and intra-species variation in DNA content of roots and distribution of roots within the soil profile. Methods   This paper develops the field application of a DNA-based technique for direct quantification of roots in soils. The method was applied to a field experiment to investigate differences in root growth of acid-soil resistant and sensitive genotypes of perennial pasture grasses in an acid soil. DNA was extracted directly from soil and species-specific DNA was quantified using quantitative real-time PCR prior to estimation of root biomass. Results   Root growth of the perennial grasses was quantified using the DNA-based technique, although separate calibration procedures were needed to convert DNA content to root mass for each species, soil layer and sampling date. Compared to acid-soil resistant genotypes, lesser root growth in acid soil layers and reduced above-ground dry matter production was observed for acid-soil sensitive genotypes. Conclusions   The DNA-based method allowed genotypic differences in root growth to be assessed directly in soil and was advantageous for rapid processing of a large number of samples. However, high replication was still required to overcome spatial variability and separate calibrations were required for different species and soil depths across sampling times. The technique demonstrated greater root growth of acid-soil resistant perennial grasses which was beneficial for their establishment and persistence. Content Type Journal Article Category Regular Article Pages 1-17 DOI 10.1007/s11104-012-1405-2 Authors Rebecca E. Haling, CSIRO Sustainable Agriculture National Research Flagship/CSIRO Plant Industry, GPO Box 1600, Canberra, ACT 2601 Australia Richard J. Simpson, CSIRO Sustainable Agriculture National Research Flagship/CSIRO Plant Industry, GPO Box 1600, Canberra, ACT 2601 Australia Richard A. Culvenor, CSIRO Sustainable Agriculture National Research Flagship/CSIRO Plant Industry, GPO Box 1600, Canberra, ACT 2601 Australia Hans Lambers, School of Plant Biology and Institute of Agriculture, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009 Australia Alan E. Richardson, CSIRO Sustainable Agriculture National Research Flagship/CSIRO Plant Industry, GPO Box 1600, Canberra, ACT 2601 Australia Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Aims   Bacteria possessing ACC deaminase activity reduce the level of stress ethylene conferring resistance and stimulating growth of plants under various biotic and abiotic stresses. The present study aims at isolating efficient ACC deaminase producing PGPR strains from the rhizosphere of rice plants grown in coastal saline soils and quantifying the effect of potent PGPR isolates on rice seed germination and seedling growth under salinity stress and ethylene production from rice seedlings inoculated with ACC deaminase containing PGPR. Methods   Soils from root region of rice growing in coastal soils of varying salinity were used for isolating ACC deaminase producing bacteria and three bacterial isolates were identified following polyphasic taxonomy. Seed germination, root growth and stress ethylene production in rice seedlings following inoculation with selected PGPR under salt stress were quantified. Results   Inoculation with selected PGPR isolates had considerable positive impacts on different growth parameters of rice including germination percentage, shoot and root growth and chlorophyll content as compared to uninoculated control. Inoculation with the ACC deaminase producing strains reduced ethylene production under salinity stress. Conclusions   This study demonstrates the effectiveness of rhizobacteria containing ACC deaminase for enhancing salt tolerance and consequently improving the growth of rice plants under salt-stress conditions. Content Type Journal Article Category Regular Article Pages 1-13 DOI 10.1007/s11104-012-1402-5 Authors Himadri Bhusan Bal, Laboratory of Soil Microbiology, Division of Crop Production, Central Rice Research Institute, Cuttack, 753006 Odisha, India Lipika Nayak, Laboratory of Soil Microbiology, Division of Crop Production, Central Rice Research Institute, Cuttack, 753006 Odisha, India Subhasis Das, Laboratory of Soil Microbiology, Division of Crop Production, Central Rice Research Institute, Cuttack, 753006 Odisha, India Tapan K. Adhya, Laboratory of Soil Microbiology, Division of Crop Production, Central Rice Research Institute, Cuttack, 753006 Odisha, India Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background   Dietary mineral deficiencies are widespread in Africa. Our previous studies in Malawi revealed population-level shortfalls in dietary calcium and selenium supply but adequate dietary magnesium (Mg) supply. Here we examine dietary Mg supply throughout Africa. Methods   Food supply data from 1961 to 2007 were compiled using Food and Agriculture Organization (FAO) Food Balance Sheets (FBSs). Magnesium supply was estimated for each country using regional food Mg composition tables. Results   Mean Mg supply in 2007 was 649 mg capita −1 d −1 , ranging from 188 mg d −1 in Eritrea to 1,828 mg d −1 in Burkina Faso. Magnesium supply was greater in West Africa than in other regions, was dominated by sorghum, maize and wheat and was correlated with calorie supply. The World Health Organization (WHO) Estimated Average Requirement (EAR) for Mg (217 mg capita −1 d −1 for adult males) was exceeded in most countries. Using the EAR cut-point method, the risk of dietary Mg deficiency in Africa is 〈4 % and unlikely to be a major problem, assuming access to sufficient food and that phytic acid does not compromise Mg absorption. Conclusions   Estimating Mg supply is highly sensitive to concentration data available for the primary staple crops. Given that soil factors profoundly affect crop Mg concentration, there is a need to increase the spatial resolution of food composition tables for the staple crops. Content Type Journal Article Category Regular Article Pages 1-9 DOI 10.1007/s11104-012-1388-z Authors Edward J. M. Joy, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, LE12 5RD UK Scott D. Young, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, LE12 5RD UK Colin R. Black, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, LE12 5RD UK E. Louise Ander, British Geological Survey, Keyworth, Nottingham, NG12 5GG UK Michael J. Watts, British Geological Survey, Keyworth, Nottingham, NG12 5GG UK Martin R. Broadley, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, LE12 5RD UK Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background and aims   Interacting effects of atmospheric N deposition on the degree to which tree demand for other nutrients is met by soil supply has seldom been explored in Mediterranean-type ecosystems. We hypothesized that patterns for the relative availability of N and P in soils will be matched by variations in process rates related to soil organic P cycling and by shifts from N to P limitation of tree growth. Methods   We examined N/P relationships in Mediterranean-fir ( Abies pinsapo ) forests from two nearby regions differing in N deposition levels. Results   N pools and transformation rates and the contribution of organic fractions to the labile P pool in soils showed increasing trends toward the pollution source. Phosphomonoesterase activity (PME) in bulk soils, root PME per unit biomass (but not per unit soil volume) and biomass accumulation in P-fertilized root-in-growth cores incubated in situ were also the highest at the sites receiving elevated N deposition, indicating P limitation. In contrast, forest stands in the region farther from the pollutant source were N-limited (preferential root growth in N-rich soil microsites) and showed lower PME activities and higher total fine root biomass. Conclusions   In the forests under elevated N deposition, higher values for an overall indicator of soil N status matched with indications of an accelerated soil organic P subcycle and P-limitation of tree growth. Content Type Journal Article Category Regular Article Pages 1-15 DOI 10.1007/s11104-012-1397-y Authors M. C. Blanes, Department of Animal Biology, Plant Biology and Ecology, University of Jaén, Campus Las Lagunillas B-3, 23071 Jaén, Spain B. Viñegla, Department of Animal Biology, Plant Biology and Ecology, University of Jaén, Campus Las Lagunillas B-3, 23071 Jaén, Spain M. T. Salido, Department of Animal Biology, Plant Biology and Ecology, University of Jaén, Campus Las Lagunillas B-3, 23071 Jaén, Spain J. A. Carreira, Department of Animal Biology, Plant Biology and Ecology, University of Jaén, Campus Las Lagunillas B-3, 23071 Jaén, Spain Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background and aims   Mixing effects during litter decomposition could occur between two or more different litter species because of the potential nutrient transfer. However, evidence of mixing effects is variable and the underlying mechanisms remain unclear. Using a three-year decomposition experiment, we aim to examine for the effects of litter mixing and position on decomposition rates and nitrogen (N) and phosphorus (P) dynamics. Methods   We studied litter decomposition of Stipa krylovii (Sk) and Astragalus galactites (Ag), two dominant species with contrasting litter quality, in a typical steppe of northern China in both single decomposition and three mixing treatments. The three mixing treatments included thorough mixing (Sk-Ag), Ag over Sk (Ag/Sk), and Sk over Ag (Sk/Ag). Results   Both the Sk-Ag and the Sk/Ag mixture had negative mixing effects on the mass loss of the litter mixture, while the Ag/Sk mixture had a neutral mixing effect. The percent mass loss was higher when the litter species was placed at the top (25.0 and 51.9 % of mass remaining for Ag and Sk, respectively) than at the bottom (38.3 and 61.8 % of mass remaining for Ag and Sk, respectively). The Sk/Ag mixture had negative effects on the release of N while all three mixing treatments had positive effects on the release of P. Conclusions   Our results indicate that: (1) mixing treatments can induce different mixing effects; (2) environmental factors likely play an important role in controlling the mixing effect; and (3) litter-mixtures have different non-additive effects on N and P, which may further increase the heterogeneity of N and P availability as the two litter species may fall differentially in terms of space and time. Content Type Journal Article Category Regular Article Pages 1-12 DOI 10.1007/s11104-012-1401-6 Authors Yulian Tan, State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, No. 20 Nanxincun, Xiangshan, Beijing, 100093 China Jin Chen, Ezhou Environmental Monitoring Station, Ezhou, 436000 China Liming Yan, State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, No. 20 Nanxincun, Xiangshan, Beijing, 100093 China Jianhui Huang, State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, No. 20 Nanxincun, Xiangshan, Beijing, 100093 China Lixin Wang, Department of Earth Sciences, Indiana University-Purdue University, Indianapolis (IUPUI), Indianapolis, IN 46202, USA Shiping Chen, State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, No. 20 Nanxincun, Xiangshan, Beijing, 100093 China Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Aims   Nitrogen deposition affect fine-root dynamics, a key factor in forest carbon and nutrient dynamics. This study aimed to elucidate the effects of increased soil inorganic nitrogen (N) levels on the fine-root dynamics of Cryptomeria japonica , which is tolerant to excess N load. Methods   An ammonium nitrate solution (28 kg ha −1  month −1 ) was applied for 3 years to plots (1 m × 2 m) in a C. japonica plantation. The elongation and disappearance of the fine roots were examined using the minirhizotron technique. Results   The N fertilization increased soil inorganic N content and lowered the soil pH. Fine-root elongation rates increased with fertilization, whereas patterns of their seasonal changes were not affected. The ratio of cumulative disappearance to cumulative elongation of fine roots was lower in the N-fertilized plots than in the control plots. The mean diameter of the fine roots was not affected by N fertilization. Conclusions   Our results suggest that C. japonica can respond to increased levels of soil inorganic N by increasing both the production and residence time of the fine roots. However, the effects of the changing soil N content are less evident for the phenology and morphology of the fine roots in C. japonica . Content Type Journal Article Category Regular Article Pages 1-11 DOI 10.1007/s11104-012-1354-9 Authors Kyotaro Noguchi, Forestry and Forest Products Research Institute, Shikoku Research Center, Kochi, 780-8077 Japan Junko Nagakura, Forestry and Forest Products Research Institute, Tsukuba, 305-8687 Japan Bohdan Konôpka, National Forest Centre, Zvolen, SK-96092 Slovakia Tadashi Sakata, Forestry and Forest Products Research Institute, Tsukuba, 305-8687 Japan Shinji Kaneko, Forestry and Forest Products Research Institute, Tsukuba, 305-8687 Japan Masamichi Takahashi, Forestry and Forest Products Research Institute, Tsukuba, 305-8687 Japan Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background and aims   Spatial distribution of soil nutrients (soil heterogeneity) and availability have strong effects on above- and belowground plant functional traits. Although there is ample evidence on the tight links between functional traits and ecosystem functioning, the role played by soil heterogeneity and availability as modulators of such relationship is poorly known. Methods   We conducted a factorial experiment in microcosms containing grasses, legumes and non-legume forbs communities differing in composition to evaluate how soil heterogeneity and availability (50 and 100 mg N) affect the links between traits and ecosystem functioning. Community-aggregated specific leaf area (SLA agg ) and specific root length (SRL agg ) were measured as both relevant response traits to soil heterogeneity and availability, and significant effect traits affecting ecosystem functioning ( i.e. , belowground biomass, β-glucosidase and acid phosphatase activities, and in situ N availability rate). Results   SRL agg was negatively and significantly associated to β-glucosidase, phosphatase and N availability rate in the high nutrient availability and heterogeneous distribution scenario. We found a significant negative relationship between SLA agg and availability rate of mineral-N under low nutrient availability conditions. Conclusions   Soil heterogeneity modulated the effects of both traits and nutrient availability on ecosystem functioning. Specific root length was the key trait associated with soil nutrient cycling and belowground biomass in contrasted heterogeneous soil conditions. The inclusion of soil heterogeneity into the trait-based response-effect framework may help to scale from plant communities to the ecosystem level. Content Type Journal Article Category Regular Article Pages 1-11 DOI 10.1007/s11104-012-1349-6 Authors Pablo García-Palacios, Departamento de Biología y Geología, Área de Biodiversidad y Conservación, Escuela Superior de Ciencias Experimentales y Tecnología, Universidad Rey Juan Carlos, c/Tulipán s/n, 28933 Móstoles, Spain Fernando T. Maestre, Departamento de Biología y Geología, Área de Biodiversidad y Conservación, Escuela Superior de Ciencias Experimentales y Tecnología, Universidad Rey Juan Carlos, c/Tulipán s/n, 28933 Móstoles, Spain Rubén Milla, Departamento de Biología y Geología, Área de Biodiversidad y Conservación, Escuela Superior de Ciencias Experimentales y Tecnología, Universidad Rey Juan Carlos, c/Tulipán s/n, 28933 Móstoles, Spain Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background and Aims   NRT1 proteins are H + -coupling nitrate transporters which belong to the family of peptide transporters (PTRs) and facilitate low and high affinity nitrate transport systems in a model plant Arabidopsis thaliana . In this study, we present the first inventory of the Cucumis sativus NRT1 family together with the transcriptional profile of CsNRT1 genes suggesting the physiological function of the family members in cucumber. Methods   Semiquantitative RT- PCR was used to analyze the level and organ-distribution of expression of CsNRT1 genes. The response of those CsNRT1s , whose transcripts were clearly detectable in vegetative tissues to different level of nitrate supply was examined through real-time PCR assays. Results   The newly identified cucumber NRT1s were given the designation according to their homology to A. thaliana AtNRT1s. The comparison of the Arabidopsis and cucumber NRT gene families, similarly to the previous comparison of NRT1s in Arabidopsis , poplar and grasses, reveals some striking differences in genes’ structure and quantity. Conclusions   The putative function of particular CsNRT1 proteins is discussed, considering the results obtained here as well as the already published studies on A. thaliana NRT1 transporters. Content Type Journal Article Category Regular Article Pages 1-16 DOI 10.1007/s11104-012-1345-x Authors M. Migocka, Institute of Experimental Biology, Department of Plant Physiology, Wroclaw University, Kanonia 6/8, 50-328 Wroclaw, Poland A. Warzybok, Institute of Experimental Biology, Department of Plant Physiology, Wroclaw University, Kanonia 6/8, 50-328 Wroclaw, Poland G. Kłobus, Institute of Experimental Biology, Department of Plant Physiology, Wroclaw University, Kanonia 6/8, 50-328 Wroclaw, Poland Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background and aims   Nitrous oxide (N 2 O) and methane (CH 4 ) can be emitted from surfaces of riparian plants. Data on the emission of these greenhouse gases by upland trees are scarce. We quantified CH 4 and N 2 O emissions from stems of Fagus sylvatica , an upland tree, and Alnus glutinosa , a riparian tree. Methods   The gas fluxes were investigated in mesocosms under non-flooded control conditions and during a flooding period using static chamber systems and gas chromatographic analyses. Results   Despite differences in the presence of an aerenchyma system, both tree species emitted N 2 O and CH 4 from the stems. Flooding caused a dramatic transient increase of N 2 O stem emissions by factors of 740 ( A. glutinosa ) and even 14,230 ( F. sylvatica ). Stem emissions of CH 4 were low and even deposition was determined ( F. sylvatica controls). The results suggest that CH 4 was transported mainly through the aerenchyma, whereas N 2 O transport occurred in the xylem sap. Conclusions   For the first time it has been demonstrated that upland trees such as F. sylvatica clearly significantly emit N 2 O from their stems despite lacking an aerenchyma. If this result is confirmed in adult trees, upland forests may constitute a new and significant source of atmospheric N 2 O. Content Type Journal Article Category Regular Article Pages 1-15 DOI 10.1007/s11104-012-1359-4 Authors Katerina Machacova, Tree Physiology, Institute of Forest Botany and Tree Physiology, University of Freiburg, Georges-Koehler-Allee 53/54, 79110 Freiburg, Germany Hans Papen, Institute for Meteorology and Climate Research, Atmospheric Environmental Research, Karlsruhe Institute of Technology, Kreuzeckbahnstrasse 19, 82467 Garmisch-Partenkirchen, Germany Jürgen Kreuzwieser, Tree Physiology, Institute of Forest Botany and Tree Physiology, University of Freiburg, Georges-Koehler-Allee 53/54, 79110 Freiburg, Germany Heinz Rennenberg, Tree Physiology, Institute of Forest Botany and Tree Physiology, University of Freiburg, Georges-Koehler-Allee 53/54, 79110 Freiburg, Germany Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background and Aims   Fenced enclosures have become an important method for re-establishing degraded grassland on the Tibetan plateau, and examination of soil seed banks may provide useful insights to understanding the effects and mechanisms of fencing enclosure on the restoration. Methods   An investigation was conducted into the effects of enclosure for 3 years on the soil seed banks of degraded natural and sown grasslands at eight study sites. Species composition, soil seed bank density and the relationships with above-ground vegetation were analysed based on 4800 soil core samples and counting of seeds extracted from soil samples. Results   After 3 years of fencing enclosure, soil seed banks differed between the different communities across the study sites. Species numbers and seed density in soil seed banks decreased from natural grassland to sown grassland, with most seeds occurring in the upper 5 cm soil layer. In these alpine grasslands, relatively few species produced high numbers of seeds, although their occurrence across the eight study sites was variable. Total vegetation cover increased with enclosure due to the colonization capacity of the vegetation rather than soil seed banks. Conclusions   This study provided evidence that soil seed banks do not play an important role in the restoration of degraded alpine grassland when using fencing enclosures. Further studies conducted over longer periods are needed to address this subject. Content Type Journal Article Category Regular Article Pages 1-16 DOI 10.1007/s11104-012-1362-9 Authors Zhan-Huan Shang, International Centre for Tibetan Plateau Ecosystem Management, State Key Laboratory of Grassland Farming Systems, College of Pastoral Agriculture Science and Technology, Lanzhou University, No. 768, Jiayuguan west road, Lanzhou City, Gansu province 730020, China Bin Deng, International Centre for Tibetan Plateau Ecosystem Management, State Key Laboratory of Grassland Farming Systems, College of Pastoral Agriculture Science and Technology, Lanzhou University, No. 768, Jiayuguan west road, Lanzhou City, Gansu province 730020, China Lu-Ming Ding, School of Life Science, Lanzhou University, Lanzhou, 73000 China Guo-Hua Ren, School of Life Science, Lanzhou University, Lanzhou, 73000 China Guo-Sheng Xin, School of Life Science, Ningxia University, Yinchuan, 750021 China Zhi-Yun Liu, International Centre for Tibetan Plateau Ecosystem Management, State Key Laboratory of Grassland Farming Systems, College of Pastoral Agriculture Science and Technology, Lanzhou University, No. 768, Jiayuguan west road, Lanzhou City, Gansu province 730020, China Yan-Long Wang, Institute of Grassland Science, Qinghai Academy of Animal and Veterinary Science, Xining, 810003 China Rui-Jun Long, International Centre for Tibetan Plateau Ecosystem Management, State Key Laboratory of Grassland Farming Systems, College of Pastoral Agriculture Science and Technology, Lanzhou University, No. 768, Jiayuguan west road, Lanzhou City, Gansu province 730020, China Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Aims   Our goal was to assess how management and sward functional diversity affect nitrogen response efficiency (NRE), the ratio of plant biomass production to supply of available nitrogen (N) in temperate grassland. Methods   A three-factorial design was employed: three sward compositions, two mowing frequencies, and two fertilization treatments. Results   NRE was largely influenced by fertilization followed by mowing frequency and sward composition. NRE was larger in unfertilized than fertilized plots, in plots cut thrice than plots cut once per year, and in control swards than in monocot- or dicot-enhanced swards. Fertilization decreased NRE through decreases in both N uptake efficiency (plant N uptake per supply of available N) and N use efficiency (NUE, biomass produced per plant N uptake) whereas mowing frequency and sward composition affected NRE through N uptake efficiency rather than NUE. The largest NRE in the control sward with 70 % monocots and 30 % dicots attests that these proportions of functional groups were best adapted in this grassland ecosystem. Conclusions   Optimum NRE may not be a target of most farmers, but it is an appropriate tool to evaluate the consequences of grassland management practices, which farmers may employ to maximize profit, on environmental quality . Content Type Journal Article Category Regular Article Pages 1-14 DOI 10.1007/s11104-012-1344-y Authors Andreas Keuter, Soil Science of Tropical and Subtropical Ecosystems, Büsgen Institute, Georg-August-Universität Göttingen, Büsgenweg 2, 37077 Göttingen, Germany Ina Hoeft, Soil Science of Tropical and Subtropical Ecosystems, Büsgen Institute, Georg-August-Universität Göttingen, Büsgenweg 2, 37077 Göttingen, Germany Edzo Veldkamp, Soil Science of Tropical and Subtropical Ecosystems, Büsgen Institute, Georg-August-Universität Göttingen, Büsgenweg 2, 37077 Göttingen, Germany Marife D. Corre, Soil Science of Tropical and Subtropical Ecosystems, Büsgen Institute, Georg-August-Universität Göttingen, Büsgenweg 2, 37077 Göttingen, Germany Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background and Aims   A substantial amount of photosynthesized plant-C is allocated belowground in grassland ecosystems where it influences the structure and function of the soil microbial community with potential implications for C cycling and storage. We applied stable isotope probing of microbial PLFAs and repeated soil sampling in a grassland over a period of 1 year to assess the role of microbial communities in the cycling of rhizodeposit-C. Methods   Pulse-labeling with 13 CO 2 was performed in a grassland site near Gent (Belgium). Soil samples were taken 24 h, 1 week, 1 month, 4 months, 9 months and 1 year following labeling and analyzed for 13 C in soil, roots and microbial PLFAs. Results   C enrichment of PLFAs occurred rapidly (within 24 h) but temporally varied across microbial groups. PLFAs indicative for fungi and gram-negative bacteria showed a faster 13 C uptake compared to gram-positive bacteria and actinomycetes. However, the relative 13 C concentrations of the latter communities increased after 1 week, while those of fungi decreased and those of gram-negative bacteria remained constant. PLFA 13 C mean residence times were much shorter for fungi compared to bacteria and actinomycetes. Conclusions   Our results indicate temporally varying rhizodeposit-C uptake by different microbial groups, and faster turnover rates of mycorrhizal versus saprotrophic fungi and fungi versus bacteria. Fungi appeared to play a major role in the initial processing and possible rapid channeling of rhizodeposit-C into the soil microbial community. Actinomycetes and gram-positive bacteria appeared to have a delayed utilization of rhizodeposit-C or to prefer other C sources upon rhizodeposition. Content Type Journal Article Category Regular Article Pages 1-13 DOI 10.1007/s11104-012-1343-z Authors Wajira K. Balasooriya, Isotope Bioscience Laboratory—ISOFYS, Ghent University, Coupure links 653, Ghent, Belgium Karolien Denef, Natural Resource Ecology Laboratory, Colorado State University, Fort Collins, CO 80523-1499, USA Dries Huygens, Isotope Bioscience Laboratory—ISOFYS, Ghent University, Coupure links 653, Ghent, Belgium Pascal Boeckx, Isotope Bioscience Laboratory—ISOFYS, Ghent University, Coupure links 653, Ghent, Belgium Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Aims   The aim was to quantify the nitrogen (N) transferred via the extra-radical mycelium of the arbuscular mycorrhizal fungus Glomus intraradices from both a dead host and a dead non-host donor root to a receiver tomato plant. The effect of a physical disruption of the soil containing donor plant roots and fungal mycelium on the effectiveness of N transfer was also examined. Methods   The root systems of the donor (wild type tomato plants or the mycorrhiza-defective rmc mutant tomato) and the receiver plants were separated by a 30 μm mesh, penetrable by hyphae but not by the roots. Both donor genotypes produced a similar quantity of biomass and had a similar nutrient status. Two weeks after the supply of 15  N to a split-root part of donor plants, the shoots were removed to kill the plants. The quantity of N transferred from the dead roots into the receiver plants was measured after a further 2 weeks. Results   Up to 10.6 % of donor-root 15 N was recovered in the receiver plants when inoculated with the arbuscular mycorrhizal fungus (AMF). The quantity of 15 N derived from the mycorrhizal wild type roots clearly exceeded that from the only weakly surface-colonised rmc roots. Hyphal length in the donor rmc root compartments was only about half that in the wild type compartments. The disruption of the soil led to a significantly increased AMF-mediated transfer of N to the receiver plants. Conclusions   The transfer of N from dead roots can be enhanced by AMF, especially when the donor roots have been formerly colonised by AMF. The transfer can be further increased with higher hyphae length densities, and the present data also suggest that a direct link between receiver mycelium and internal fungal structures in dead roots may in addition facilitate N transfer. The mechanical disruption of soil containing dead roots may increase the subsequent availability of nutrients, thus promoting mycorrhizal N uptake. When associated with a living plant, the external mycelium of G. intraradices is readily able to re-establish itself in the soil following disruption and functions as a transfer vessel. Content Type Journal Article Category Regular Article Pages 1-15 DOI 10.1007/s11104-012-1372-7 Authors Anja Müller, Institute of Vegetable and Ornamental Crops (IGZ), Theodor-Echtermeyer-Weg 1, 14979 Grossbeeren, Germany Eckhard George, Institute of Vegetable and Ornamental Crops (IGZ), Theodor-Echtermeyer-Weg 1, 14979 Grossbeeren, Germany Elke Gabriel-Neumann, Faculty of Food and Agriculture/Department of Aridland Agriculture, United Arab Emirates University, P.O. Box 17555, Al-Ain, United Arab Emirates Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background and aims   The roots of tussock-forming plants contribute to the formation of microtopographic features in many ecosystems, but the dynamics of such roots are poorly understood. We examined the spatial heterogeneity of tussock fine root dynamics to investigate allocation patterns and the role of root productivity in the persistence of tussock structures. Methods   We compared the spatial variability of fine root (〈1 mm, 1–2 mm) density, biomass, % live, allocation, turnover rate (using bomb 14C), and productivity of four Carex stricta Lam.-dominated tussock meadows in the upper Midwest, USA (3 reference, 1 restored site). Results   Relative to underlying microsites, tussocks were warm, dry, and high in root density, productivity, % live biomass, and turnover. Root productivity averaged 649 g m −2  yr −1 (±208) in reference sites, comprised 57 % (±10) of total net production, and was concentrated in tussocks (70 % ± 4). Root turnover rate averaged 0.63 yr −1 (±0.08), but tussocks had ~50 % faster root turnover than the underlying soil, and 〈1 mm roots turned over ~40 % faster than 1–2 mm roots. Conclusions   Our detailed analysis of the spatial heterogeneity of tussock root dynamics suggests that high allocation and elevated turnover of tussock roots facilitates organic matter accumulation and tussock persistence over time. Content Type Journal Article Category Regular Article Pages 1-15 DOI 10.1007/s11104-012-1360-y Authors Beth A. Lawrence, Department of Botany, University of Wisconsin-Madison, 430 Lincoln Drive, Madison, WI 53706, USA Timothy J. Fahey, Department of Natural Resources, Cornell University, 12 Fernow Hall, Ithaca, NY 14853, USA Joy B. Zedler, Department of Botany, University of Wisconsin-Madison, 430 Lincoln Drive, Madison, WI 53706, USA Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background   Zinc (Zn) deficiency is one of the important abiotic factors limiting rice productivity worldwide and also a widespread nutritional disorder affecting human health. Given that rice is a staple for populations in many countries, studies of Zn dynamics and management in rice soils is of great importance. Scope   Changing climate is forcing the growers to switch from conventional rice transplanting in flooded soils to water-saving cultivation, including aerobic rice culture and alternate wetting and drying system. As soil properties are changed with altered soil and water management, which is likely to affect Zn solubility and plant availability and should be considered before Zn management in rice. In this review, we critically appraise the role of Zn in plant biology and its dynamics in soil and rice production systems. Strategies and options to improve Zn uptake and partitioning efficiency in rice by using agronomic, breeding and biotechnological tools are also discussed. Conclusions   Although soil application of inorganic Zn fertilizers is widely used, organic and chelated sources are better from economic and environmental perspectives. Use of other methods of Zn application (such as seed treatment, foliar application etc., in association with mycorrhizal fungi) may improve Zn-use efficiency in rice. Conventional breeding together with modern genomic and biotechnological tools may result in development of Zn-efficient rice genotypes that should be used in conjunction with judicious fertilization to optimize rice yield and grain Zn content. Content Type Journal Article Category Review Article Pages 1-24 DOI 10.1007/s11104-012-1346-9 Authors Hafeez-ur Rehman, Department of Crop Physiology, University of Agriculture, Faisalabad, 38040 Pakistan Tariq Aziz, Institute of Soil and Environmental Sciences, University of Agriculture, Faisalabad, 38040 Pakistan Muhammad Farooq, Institute of Plant Nutrition, Justus-Liebig-University, Heinrich-Buff-Ring 26-32, 35392 Giessen, Germany Abdul Wakeel, Institute of Soil and Environmental Sciences, University of Agriculture, Faisalabad, 38040 Pakistan Zed Rengel, School of Earth and Environment, The University of Western Australia, Crawley, WA 6009, Australia Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background and Aims   Roots express morphological and physiological plasticity that may be adaptations for efficient nutrient capture when soil nutrients are heterogeneous in space and time. In terms of nutrient capture per unit of carbon invested in roots, morphological plasticity should be more advantageous when nutrient patches are stable in time, and physiological plasticity when nutrients are variable in time. Methods   Here we examined both traits in two Pinus species, two Liquidambar species, two Solidago species, Ailanthus altissima and Callistephus chinesis , grown in pots where the same total level of nutrient addition was provided in a factorial experiment with different levels of spatial and temporal variability. Results   Total plant root growth, Root/Shoot ratios and morphological plasticity were less when nutrients were temporally variable instead of stable. Physiological plasticity was more variable than morphological across treatments and species and was not predictably greater when nutrient supply was pulsed instead of constant. Large variability, especially in physiological plasticity, was observed, and physiological plasticity was greater in non-woody than in woody species. Conclusions   Our results suggest that the two traits differ in environmental factors that control their expression, and that the nature of nutrient patchiness may have more direct impact on the evolution of morphological than physiological plasticity. Content Type Journal Article Category Regular Article Pages 1-12 DOI 10.1007/s11104-012-1336-y Authors Pu Mou, State Key Laboratory of Earth Surface Processes and Resource Ecology & Ministry of Education Key Laboratory for Biodiversity Science and Engineering, Beijing Normal University, Beijing, 100875 China Robert H. Jones, Eberly College of Art and Sciences, West Virginia University, Morgantown, WV USA Zengquan Tan, State Key Laboratory of Earth Surface Processes and Resource Ecology & Ministry of Education Key Laboratory for Biodiversity Science and Engineering, Beijing Normal University, Beijing, 100875 China Zhe Bao, Department of Biological Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA Hongmei Chen, State Key Laboratory of Earth Surface Processes and Resource Ecology & Ministry of Education Key Laboratory for Biodiversity Science and Engineering, Beijing Normal University, Beijing, 100875 China Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Aims   We examine how root system demography and morphology are affected by air warming and multiple, simultaneous climate change drivers. Methods   Using minirhizotrons, we studied root growth, morphology, median longevity, risk of mortality and standing root pool in the upper soil horizon of a temperate grassland ecosystem for 3 years. Grassland monoliths were subjected to four climate treatments in a replicated additive design: control (C); elevated temperature (T); combined T and summer precipitation reduction (TD); combined TD and elevated atmospheric CO 2 (TDCO 2 ). Results   Air warming (C vs T) and the combined climate change treatment (C vs TDCO 2 ) had a positive effect on root growth rate and standing root pool. However, root responses to climate treatment varied depending on diameter size class. For fine roots (≤ 0.1 mm), new root length and mortality increased under warming but decreased in response to elevated CO 2 (TD vs TDCO 2 ); for coarse roots (〉 0.2 mm), length and mortality increased under both elevated CO 2 and combined climate change drivers. Conclusions   Our data suggest that the standing roots pool in our grassland system may increase under future climatic conditions. Contrasted behaviour of fine and coarse roots may correspond to differential root activity of these extreme diameter classes in future climate. Content Type Journal Article Category Regular Article Pages 1-14 DOI 10.1007/s11104-012-1371-8 Authors R. Pilon, INRA, UR874, Grassland Ecosystem Research Team, 5 chemin de Beaulieu, 63100 Clermont-Ferrand, France C. Picon-Cochard, INRA, UR874, Grassland Ecosystem Research Team, 5 chemin de Beaulieu, 63100 Clermont-Ferrand, France J. M. G. Bloor, INRA, UR874, Grassland Ecosystem Research Team, 5 chemin de Beaulieu, 63100 Clermont-Ferrand, France S. Revaillot, INRA, UR874, Grassland Ecosystem Research Team, 5 chemin de Beaulieu, 63100 Clermont-Ferrand, France E. Kuhn, INRA, UR341, Mathématiques et Informatique Appliquées, 78350 Jouy-en-Josas, France R. Falcimagne, INRA, UR874, Grassland Ecosystem Research Team, 5 chemin de Beaulieu, 63100 Clermont-Ferrand, France P. Balandier, Irstea, Research Unit on Forest Ecosystems (EFNO), 45290 Nogent-sur-Vernisson, France J.-F. Soussana, INRA, UR874, Grassland Ecosystem Research Team, 5 chemin de Beaulieu, 63100 Clermont-Ferrand, France Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background and Aims   Soil mineralization, nitrification, and dynamic changes in abundance of ammonia-oxidizing bacteria (AOB) and archaea (AOA) were studied to validate our hypothesis that soil mineralization and nitrification decreased along the chronosequence of rice cultivation. Methods   Paddy soils with a 300, 700 and 2000-year cultivation history (P300, P700 and P2000) were selected to study net mineralization and nitrification processes. Dynamic abundance of AOB and AOA was estimated by quantifying their respective amoA gene copies. Results   The net mineralization rate was higher for P300 than P700 and P2000. Potential nitrification ( N p ) and average nitrification rates ( V a ) were similar for P300 and P700 soils, but the simulated potential nitrification rate ( V p ) and nitrification rate (k 1 ) was 72 % and 88 % higher for P300 than P700, respectively. V a was about 70 % lower than for P2000 than P300 and P700. AOB amoA gene copies were higher for P300 than P700 and P2000, whereas AOA abundance did not show significant differences. AOB abundance showed a positive response to NH 4 supply but AOA did not. Conclusions   Both N mineralization and nitrification were depressed with increased cultivation time. Archaea responded to mineralization positively rather than nitrification, which suggested that readily mineralized organic matter may play an important role in AOA. Content Type Journal Article Category Regular Article Pages 1-10 DOI 10.1007/s11104-012-1377-2 Authors Xianjun Jiang, Key Laboratory of Eco-environments in Three Gorges Reservoir Region (Ministry of Education), College of Resources and Environment, Southwest University, 2 Tiansheng Road, Beibei, Chongqing 400715, China Wei Liu, Key Laboratory of Eco-environments in Three Gorges Reservoir Region (Ministry of Education), College of Resources and Environment, Southwest University, 2 Tiansheng Road, Beibei, Chongqing 400715, China Qin Liu, Institute of Soil Science, Chinese Academy of Sciences, 71 Eastern Beijing Road, NanJing, 210008 China Zhongjun Jia, Institute of Soil Science, Chinese Academy of Sciences, 71 Eastern Beijing Road, NanJing, 210008 China Alan L. Wright, Everglades Research & Education Center, University of Florida, Belle Glade, FL 33430, USA Zhihong Cao, Institute of Soil Science, Chinese Academy of Sciences, 71 Eastern Beijing Road, NanJing, 210008 China Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background and Aims   Increased N availability induced by agricultural fertilization applications and atmospheric N deposition may affect plant nutrient resorption in temperate wetlands. However, the relationship between nutrient resorption and N availability is still unclear, and most studies have focused on leaf nutrient resorption only. The aim of our study was to examine the response of leaf and non-leaf organ nutrient resorption to N enrichment in a temperate freshwater wetland. Methods   We conducted a 7-year N addition experiment to investigate the effects of increased N loading on leaf, sheath and stem nutrient (N and P) resorption of two dominant species ( Deyeuxia angustifolia and Glyceria spiculosa ) in a freshwater marsh in the Sanjiang Plain, Northeast China. Results   Our results showed that, for both leaf and non-leaf organs (sheath and stem), N addition decreased N resorption proficiency and hence increased litter N concentration. Moreover, the magnitude of N addition effect on N resorption proficiency varied with fertilization rates for D. angustifolia sheaths and stems, and G. spiculosa leaves. However, increased N loading produced inconsistent impacts on N and P resorption efficiencies and P resorption proficiency, and the effects only varied with species and plant organs. In addition, N enrichment increased litter mass and altered litter allocation among leaf, sheath and stem. Conclusions   Our results highlight that leaf and non-leaf organs respond differentially to N addition regarding N and P resorption efficiencies and P resorption proficiency, and also suggest that N enrichment in temperate freshwater wetlands would alter plant internal nutrient cycles and increase litter quality and quantity, and thus substantially influence ecosystem carbon and nutrient cycles. Content Type Journal Article Category Regular Article Pages 1-10 DOI 10.1007/s11104-012-1370-9 Authors Rong Mao, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, 3195 Weishan Road, Changchun, 130012 China Chang-Chun Song, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, 3195 Weishan Road, Changchun, 130012 China Xin-Hou Zhang, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, 3195 Weishan Road, Changchun, 130012 China Xian-Wei Wang, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, 3195 Weishan Road, Changchun, 130012 China Zheng-Hai Zhang, Yunnan Academy of Forestry, 2 Lan’an Road, Kunming, 650204 China Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Aim   Zinc (Zn) fertilization is an effective agronomic tool for Zn biofortification of wheat for overcoming human Zn deficiency. But it still needs to be evaluated across locations with different management practices and wheat cultivars, since grain Zn concentrations may be significantly affected by locations, cultivars and management. Materials   Field experiments were conducted over 3 years with the following four Zn treatments: nil Zn, soil Zn application, foliar Zn application and soil + foliar Zn application to explore the impact of Zn fertilization in Zn biofortification of wheat. The experiments were conducted at a total of 23 experimental site-years in China, India, Kazakhstan, Mexico, Pakistan, Turkey and Zambia. Results   The results showed that foliar Zn application alone or in combination with soil application, significantly increased grain Zn concentrations from 27 mg kg −1 at nil Zn to 48 and 49 mg kg −1 across all of 23 site-years, resulting in increases in grain Zn by 84 % and 90 %, respectively. Overall, soil Zn deficiency was not a growth limiting factor on the experimental sites. A significant grain yield increase in response to soil Zn fertilization was found only in Pakistan. When all locations and cropping years are combined, soil Zn fertilization resulted in about 5 % increase in grain yield. Foliar Zn application did not cause any adverse effect on grain yield, even slightly improved the yield. Across the 23 site-years, soil Zn application had a small effect on Zn concentration of leaves collected before foliar Zn application, and increased grain Zn concentration only by 12 %. The correlation between grain yield and the effectiveness of foliar Zn application on grain Zn was condition dependent, and was positive and significant at certain conditions. Conclusion   Foliar Zn application resulted in successful biofortification of wheat grain with Zn without causing yield loss. This effect of Zn fertilization occurred irrespective of the soil and environmental conditions, management practices applied and cultivars used in 23 site-years. Foliar Zn fertilizer approach can be locally adopted for increasing dietary Zn intake and fighting human Zn deficiency in rural areas. Content Type Journal Article Category Regular Article Pages 1-12 DOI 10.1007/s11104-012-1369-2 Authors C. Q. Zou, Department of Plant Nutrition, Key Laboratory of Plant-Soil Interaction, MOE; Center for Resources, Environment and Food Security, China Agricultural University, Beijing, 100193 People’s Republic of China Y. Q. Zhang, Department of Plant Nutrition, Key Laboratory of Plant-Soil Interaction, MOE; Center for Resources, Environment and Food Security, China Agricultural University, Beijing, 100193 People’s Republic of China A. Rashid, Pakistan Academy of Sciences, Islamabad, Pakistan H. Ram, Punjab Agricultural University, Ludhiana, Punjab India E. Savasli, Transitional Zone Agricultural Research Institute, 26002 Eskisehir, Turkey R. Z. Arisoy, BD International Agricultural research Institute, 42020 Konya, Turkey I. Ortiz-Monasterio, CIMMYT International, AP370, PO Box 60326, Houston, TX 77205, USA S. Simunji, Golden Valley Agricultural Research Trust, P.O. Box 50834, Lusaka, Zambia Z. H. Wang, College of Resources and Environment, Northwest Agricultural and Forestry University, Yangling, Shaanxi 712100, People’s Republic of China V. Sohu, Punjab Agricultural University, Ludhiana, Punjab India M. Hassan, Plant Breeding and Genetics Division, Nuclear Institute for Agriculture and Biology (NIAB), Faisalabad, Pakistan Y. Kaya, BD International Agricultural research Institute, 42020 Konya, Turkey O. Onder, Transitional Zone Agricultural Research Institute, 26002 Eskisehir, Turkey O. Lungu, Department of Soil Science, University of Zambia, Lusaka, Zambia M. Yaqub Mujahid, National Agricultural Research Centre, 44000 Islamabad, Pakistan A. K. Joshi, CIMMYT, POB 5186, Kathmandu, Nepal Y. Zelenskiy, CIMMYT, P.O. Box 1446, Astana, 010000 Kazakhstan F. S. Zhang, Department of Plant Nutrition, Key Laboratory of Plant-Soil Interaction, MOE; Center for Resources, Environment and Food Security, China Agricultural University, Beijing, 100193 People’s Republic of China I. Cakmak, Faculty of Engineering and Natural Sciences, Sabanci University, 34956 Istanbul, Turkey Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background and aims   Boron (B) deficiency depresses grain set and grain yield of wheat and maize while having little effect on their vegetative growth. This paper describes effects of B deficiency in rice and how these vary with planting season and variety. Methods   Three rice varieties (KDML105, CNT1, SPR1) were grown in sand culture without (B0) and with 10 μM (B10) B added to the nutrient solution, in the cool season of 2007/08 and 2008/09 and the hot season of 2011 in Chiang Mai, Thailand (18°47′N, 98°59′E). Boron responses were measured in growth and yield parameters, pollen viability and B concentration of the flag leaf and anthers at anthesis. Results   Grain weight was strongly depressed by B deficiency ranging from 28 % in SPR1 to 79 % in CNT1, and the yield was much lower in the cool season than in the hot season plantings. The variation in grain weight was closely associated with grain set and number of spikelets but not with shoot dry weight or tillering. Grain set was closely related to pollen viability, and both were increased with increasing anther B concentration at 〉20 mg B kg −1 . In addition to its adverse effect on grain set, B deficiency also depressed grain filling and weight of individual grains in rice. Conclusions   Boron deficiency depressed rice grain yield through adverse effects on reproductive growth, panicle and spikelet formation and grain filling, in addition to grain set as in wheat and maize. Content Type Journal Article Category Regular Article Pages 1-9 DOI 10.1007/s11104-012-1323-3 Authors S. Lordkaew, Center for Agricultural Resource System Research, Faculty of Agriculture, Chiang Mai University, Chiang Mai, 50200 Thailand S. Konsaeng, Department of Plant Science and Natural Resources, Faculty of Agriculture, Chiang Mai University, Chiang Mai, 50200 Thailand J. Jongjaidee, Department of Plant Science and Natural Resources, Faculty of Agriculture, Chiang Mai University, Chiang Mai, 50200 Thailand B. Dell, Sustainable Ecosystem Research Institute, Murdoch University, Perth, 6150 Australia B. Rerkasem, Plant Genetic Resource and Nutrition Laboratory, Chiang Mai University, Chiang Mai, 50200 Thailand S. Jamjod, Department of Plant Science and Natural Resources, Faculty of Agriculture, Chiang Mai University, Chiang Mai, 50200 Thailand Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Aims   Although water conservation in rice production has become increasingly important, the effects of water management on the allocation and dynamics of carbon (C) within the rice-soil system remain unknown. Methods   We compared the allocation and dynamics of C assimilated by rice under continuously flooded, non-flooded and alternate water regimes. Rice ( Oryza sative L. cv. Luliangyou 996) was labeled with 14 CO 2 and harvested 7 times within 45 days. Results   More 14 C was released from roots into the soil in non-flooded and alternate water regimes treatments. Microbial 14 C decreased with time after the labeling and was lowest under flooded condition. Roots and rhizomicrobial respiration followed the order of non-flooded 〉 alternate water regimes 〉 flooded treatment. Water management affected 14 C distribution in aggregates with more 14 C in macroaggregates in the non-flooded treatment. Estimated amounts of C transferred remaining belowground by rice 45 days after labeling were 1,986, 2,827 and 2,472 kg C ha −1 , of which rhizodeposition accounted for about 41 %, 16 % and 30 % of C transferred belowground under non-flooded, flooded and alternate water regimes, respectively. Conclusions   Water management affected the allocation and dynamics of recently assimilated C within the rice-soil system and also changed the relative contribution of rhizodeposition to C transferred belowground. This study suggests the differences in the driving mechanisms of C sequestration under flooded vs. non-flooded and alternate water regimes. Content Type Journal Article Category Regular Article Pages 1-13 DOI 10.1007/s11104-012-1327-z Authors Jing Tian, Key Laboratory of Plant-Soil Interactions, Ministry of Education; and College of Resources and Environmental Sciences, China Agricultural University, Beijing, 100193 China Johanna Pausch, Department of Agroecosystem Research, University of Bayreuth, 95440 Bayreuth, Germany Mingsheng Fan, Key Laboratory of Plant-Soil Interactions, Ministry of Education; and College of Resources and Environmental Sciences, China Agricultural University, Beijing, 100193 China Xiaolin Li, Key Laboratory of Plant-Soil Interactions, Ministry of Education; and College of Resources and Environmental Sciences, China Agricultural University, Beijing, 100193 China Qiyuan Tang, College of Agriculture, Hunan Agricultural University, 410128 Changsha, China Yakov Kuzyakov, Department of Soil Science of Temperate Ecosystems, University of Göttingen, 37077 Göttingen, Germany Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background and aims   Little information is currently available regarding the number of species of black-foot and Petri disease pathogens present in soil and their capacity to infect grapevine roots and reach the xylem vessels. Methods   Seedlings of grapevine rootstock 41-B, and cvs. Bobal and Palomino were planted both in pots containing soil samples collected from commercial vineyards and in nursery fields. Roots and xylem vessels were later analyzed for fungal isolation. Results   Black-foot pathogens: Ilyonectria alcacerensis , I. macrodidyma , I. novozelandica and I. torresensis were frequently isolated from roots of seedlings grown in all soils evaluated, whereas Petri disease pathogens: Cadophora luteo-olivacea , Phaeoacremonium aleophilum , Pm. parasiticum and Phaeomoniella chlamydospora were only isolated from xylem vessels of seedlings grown in nursery soils, with a low incidence. Ilyonectria alcacerensis, I. novozelandica and I. torresensis were isolated for the first time from grapevines in Spain, and Pm. parasiticum and Ca. luteo-olivacea were detected for the first time in nursery soils. Conclusions   Our results confirm nursery and vineyard soils as an important inoculum source for black-foot pathogens and demonstrate the presence of several Petri disease pathogens in nursery soils. Content Type Journal Article Category Regular Article Pages 1-9 DOI 10.1007/s11104-012-1333-1 Authors Carlos Agustí-Brisach, Instituto Agroforestal Mediterráneo, Universidad Politécnica de Valencia, Camino de Vera s/n, 46022 Valencia, Spain David Gramaje, Department of Crop Protection, Institute for Sustainable Agriculture (IAS), Spanish National Research Council (CSIC), Alameda del Obispo s/n, APDO 4084, 14004 Córdoba, Spain José García-Jiménez, Instituto Agroforestal Mediterráneo, Universidad Politécnica de Valencia, Camino de Vera s/n, 46022 Valencia, Spain Josep Armengol, Instituto Agroforestal Mediterráneo, Universidad Politécnica de Valencia, Camino de Vera s/n, 46022 Valencia, Spain Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background and Aims   Ecosystem recovery following disturbance requires the reestablishment of key soil biogeochemical processes. This long-term 7 year study describes effects of organic material, moisture, and vegetation on soil microbial community development in the Athabasca Oil Sands Region of Western Canada. Methods   Phospholipid fatty acid analysis was used to characterize and compare soil microbial community composition and development on reclaimed and natural forest sites. Additionally, we conducted a laboratory moisture manipulation experiment. Results   The use of forest floor material as an organic amendment resulted in a greater percent cover of upland vegetation and placed the soil microbial community on a faster trajectory towards ecosystem recovery than did the use of a peat amendment. The soil microbial composition within the reclaimed sites exhibited a greater response to changes in moisture than did the soil microbial communities from natural sites. Conclusion   Our research shows that the use of native organic amendment (forest floor) on reclaimed sites, and the associated establishment of native vegetation promote the development of soil microbial communities more similar to those found on natural forest sites. Additionally, soil microbial communities from natural sites may be more resistant to changes in soil moisture than those found on reclaimed sites. Content Type Journal Article Category Regular Article Pages 1-14 DOI 10.1007/s11104-012-1306-4 Authors Aria S. Hahn, Department of Renewable Resources, University of Alberta, 3-40C Earth Sciences Building, Edmonton, Alberta, Canada T6G 2E3 Sylvie A. Quideau, Department of Renewable Resources, University of Alberta, 3-40C Earth Sciences Building, Edmonton, Alberta, Canada T6G 2E3 Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Purpose   We attempted to determine the contribution of entrapped gas bubbles to the soil methane (CH 4 ) pool and their role in CH 4 emissions in rice paddies open to the atmosphere. Methods   We buried pots with soil and rice in four treatments comprising two atmospheric CO 2 concentrations (ambient and ambient +200 μmol mol −1 ) and two soil temperatures (ambient and ambient +2 °C). Pots were retrieved for destructive measurements of rice growth and the gaseous CH 4 pool in the soil at three stages of crop development: panicle formation, heading, and grain filling. Methane flux was measured before pot retrieval. Results   Bubbles that contained CH 4 accounted for a substantial fraction of the total CH 4 pool in the soil: 26–45 % at panicle formation and 60–68 % at the heading and grain filling stages. At panicle formation, a higher CH 4 mixing ratio in the bubbles was accompanied by a greater volume of bubbles, but at heading and grain filling, the volume of bubbles plateaued and contained ~35 % CH 4 . The bubble-borne CH 4 pool was closely related to the putative rice-mediated CH 4 emissions measured at each stage across the CO 2 concentration and temperature treatments. However, much unexplained variation remained between the different growth stages, presumably because the CH 4 transport capacity of rice plants also affected the emission rate. Conclusions   The gas phase needs to be considered for accurate quantification of the soil CH 4 pool. Not only ebullition but also plant-mediated emission depends on the gaseous-CH 4 pool and the transport capacity of the rice plants. Content Type Journal Article Category Regular Article Pages 1-13 DOI 10.1007/s11104-012-1356-7 Authors Takeshi Tokida, National Institute for Agro-Environmental Sciences, 3-1-3 Kannondai, Tsukuba, Ibaraki 305-8604, Japan Weiguo Cheng, Faculty of Agriculture, Yamagata University, 1-23 Wakaba-cho, Tsuruoka, Yamagata 997-8555, Japan Minaco Adachi, National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506, Japan Toshinori Matsunami, Akita Prefectural Agriculture, Forestry and Fisheries Research Center, 34-1 Yuwaaikawa-aza-genpachizawa, Akita, 010-1231 Japan Hirofumi Nakamura, Taiyo Keiki Co., Ltd, Tokyo, 114-0032, 1-12-3 Nakajujo, Kita-ku, Tokyo 114-0032, Japan Masumi Okada, Faculty of Agriculture, Iwate University, 3-18-8 Ueda, Morioka, Iwate 020-8550, Japan Toshihiro Hasegawa, National Institute for Agro-Environmental Sciences, 3-1-3 Kannondai, Tsukuba, Ibaraki 305-8604, Japan Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background and Aims   Phosphorus (P) is commonly one of most limiting nutrients in tropical and subtropical forests, but whether P limitation would be exacerbated during forest succession remains unclear. Methods   Soil phosphatase activity is often used as an indicator of P limitation. Here we examined soil acid phosphatase activity (APA) underneath tree species in pine forest (PF), mixed pine and broadleaf forest (MF) and monsoon evergreen broadleaf forest (MEBF) which represented the early, middle and late successional stages of subtropical forests in China, respectively. We also analyzed other indicators of P status (soil available P and N and P stoichiometry of the tree species). Results   APA or APA per unit soil organic carbon under tree species was relatively low in the early successional forest. Different from PF and MF, soil available P beneath the tree species was lower than in the bulk soils in MEBF. Soil APA was closely related to N:P ratios of tree species across all three forests. Conclusions   Our results imply that P limitation increases during forest succession at our site. The dominant tree species with low soil APAs in MEBF are likely more P-limited than other tree species. Content Type Journal Article Category Regular Article Pages 1-11 DOI 10.1007/s11104-012-1355-8 Authors Wenjuan Huang, Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650 China Juxiu Liu, Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650 China Ying Ping Wang, Marine and Atmospheric Research, CSIRO, Aspendale, VIC 3195, Australia Guoyi Zhou, Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650 China Tianfeng Han, Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650 China Yin Li, Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650 China Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background and aims   The role of the root system in mediating crop yields has recently been emphasised, resulting in several laboratory approaches for phenotyping root traits. We aimed to determine the existence of, and reasons for, genotypic variation in wheat ( Triticum aestivum L.) root penetration of strong wax layers. Methods   Three contrasting groups (UK elite lines, CIMMYT lines and near-isogenic lines of cv Mercia containing dwarfing and semi-dwarfing Rht alleles) comprising 18 different genotypes with contrasting phenologies were studied. We determined the ability of roots of these genotypes to penetrate strong wax layers and the angular spread of the root systems. Results   There were no intrinsic differences in root system ability to penetrate strong wax layers (consistent with the similar root diameter of all lines) since greater root penetration was simply related to more root axes. Recording root penetration of concentric zones of the wax layer demonstrated that cv. Battalion had a root system with a smaller angular spread than cv. Robigus, which had the root system with the greatest angular spread. Conclusions   There was limited genotypic variability in root penetration of strong layers within the wheat cultivars studied. A key challenge will be to determine the physiological and agronomic significance of the variation in root angular spread. Content Type Journal Article Category Regular Article Pages 1-9 DOI 10.1007/s11104-012-1342-0 Authors W. R. Whalley, Rothamsted Research, Harpenden, West Common, Hertfordshire, AL5 2JQ UK I. C. Dodd, The Lancaster Environment Centre, Lancaster University, Lancaster, LA1 4YQ UK C. W. Watts, Rothamsted Research, Harpenden, West Common, Hertfordshire, AL5 2JQ UK C. P. Webster, Rothamsted Research, Harpenden, West Common, Hertfordshire, AL5 2JQ UK A. L. Phillips, Rothamsted Research, Harpenden, West Common, Hertfordshire, AL5 2JQ UK J. Andralojc, Rothamsted Research, Harpenden, West Common, Hertfordshire, AL5 2JQ UK R. P. White, Rothamsted Research, Harpenden, West Common, Hertfordshire, AL5 2JQ UK W. J. Davies, The Lancaster Environment Centre, Lancaster University, Lancaster, LA1 4YQ UK M. A. J. Parry, Rothamsted Research, Harpenden, West Common, Hertfordshire, AL5 2JQ UK Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background & Aims   The effects of an alfalfa plant ( Medicago sativa L.) hydrolysate-based biostimulant (EM) containing triacontanol (TRIA) and indole-3-acetic acid (IAA) were tested in salt-stressed maize plants. Methods   Plants were grown for 2 weeks in the absence of NaCl or in the presence (25, 75 and 150 mM). On the 12th day, plants were supplied for 48 h with 1.0 mg L −1 EM or 11.2 μM TRIA. Results   EM and TRIA stimulated the growth and nitrogen assimilation of control plants to a similar degree, while NaCl reduced plant growth, SPAD index and protein content. EM or TRIA increased plant biomass under salinity conditions. Furthermore, EM induced the activity of enzymes functioning in nitrogen metabolism. The activity of antioxidant enzymes and the synthesis of phenolics were induced by salinity, but decreased after EM treatment. The enhancement of phenylalanine ammonia-lyase (PAL) activity and gene expression by EM was consistent with the increase of flavonoids. Conclusion   The present study proves that the EM increases plant biomass even when plants are grown under salinity conditions. This was likely because EM stimulated plant nitrogen metabolism and antioxidant systems. Therefore, EM may be proposed as bioactive product in agriculture to help plants overcome stress situations. Content Type Journal Article Category Regular Article Pages 1-14 DOI 10.1007/s11104-012-1335-z Authors Andrea Ertani, Dipartimento di Agronomia Animali Alimenti Risorse Naturali e Ambiente, Università degli Studi di Padova, Agripolis, Viale dell’Università 16, 35020 Legnaro, Padova, Italy Michela Schiavon, Dipartimento di Agronomia Animali Alimenti Risorse Naturali e Ambiente, Università degli Studi di Padova, Agripolis, Viale dell’Università 16, 35020 Legnaro, Padova, Italy Adele Muscolo, Dipartimento di Gestione dei Sistemi Agrari e Forestali, Facoltà di Agraria Università “Mediterranea” di Reggio Calabria, Feo di Vito, 89060 Reggio Calabria, Italy Serenella Nardi, Dipartimento di Agronomia Animali Alimenti Risorse Naturali e Ambiente, Università degli Studi di Padova, Agripolis, Viale dell’Università 16, 35020 Legnaro, Padova, Italy Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background and aims   The relationship between tree species and soil nutrient availability is critical for evaluating plantation succession and promoting forest restoration. This study was conducted to evaluate the impact of exotic and native tress species on soil nutrient availability. Methods   Four exotic species ( Eucalyptus urophylla , E. tereticornis , Acaia auriculaeformis , A. mangium ) and four native species ( Castanopsis fissa , Schima superba , C. hystrix , Michelia macclurei ) were planted and grown for one-year. Soil solution (DOC, DON, NH 4 −N, NO 3 −N) was sampled and analyzed during the study. After the experiment, soil properties were determined, and plant tissues were analyzed. Results   DOC levels were greater in soils with trees planted than controls without trees. Compared to native species, exotic species had much faster growth rates and greatly reduced DON and NO 3 −N concentrations. Exotic species always had less P concentrations in leaves and stems than native species. Furthermore, N-fixing A. auriculaeformis led to greater soil available P compared to other species. Conclusions   Based on these findings, we provide some recommendations for afforestation practice. This study highlights that a better understanding of the pros and cons of exotic species would be beneficial to advance afforestation in China and the world. Content Type Journal Article Category Regular Article Pages 1-12 DOI 10.1007/s11104-012-1353-x Authors Faming Wang, Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Botanical Garden, Chinese Academy of Sciences, Xingke Road 723, Tianhe District, Guangzhou, People’s Republic of China 510650 Weixing Zhu, Department of Biological Sciences, State University of New York-Binghamton, Binghamton, NY 13902, USA Bi Zou, Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Botanical Garden, Chinese Academy of Sciences, Xingke Road 723, Tianhe District, Guangzhou, People’s Republic of China 510650 Deborah A. Neher, Department of Plant and Soil Science, University of Vermont, Burlington, VT 05405, USA Shenglei Fu, Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Botanical Garden, Chinese Academy of Sciences, Xingke Road 723, Tianhe District, Guangzhou, People’s Republic of China 510650 Hanping Xia, Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Botanical Garden, Chinese Academy of Sciences, Xingke Road 723, Tianhe District, Guangzhou, People’s Republic of China 510650 Zhian Li, Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Botanical Garden, Chinese Academy of Sciences, Xingke Road 723, Tianhe District, Guangzhou, People’s Republic of China 510650 Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X