ALBERT

Description:    Successful revegetation of saline land is dependent on seedling recruitment to maintain vegetative cover for lowering of saline water tables and agricultural production. This paper examines seasonal effects of tree/shrub microsites and leaf-litter on soil conditions and seedling recruitment in a saline grazing system planted with Eucalyptus sargentii Maiden tree rows (15 years old) and saltbush ( Atriplex spp.) inter-rows (8 years old). Salt bush rows were also slightly mounded. As litter accumulation decreases with increased distance from tree rows, soil conditions and seedling recruitment were compared between paired bare and litter-covered zones within three microsites: tree row, saltbush row 1 (saltbush row closest, viz. 3–4 m, to tree row) and saltbush mid-row (middle row of saltbush between adjacent tree rows, viz. 7–9 m from trees). Microsite facilitation in winter was negligible due to moderate temperatures and high water availability. However, in warmer months, saltbush mid-row microsites were most favourable for recruitment. Tree microsites inhibited recruitment through increased salinity, water repellency and potential root competition. Despite negative interactions within the tree row, trees indirectly facilitated recruitment through litter provision in saltbush rows. Overall, litter increased seedling densities through amelioration of soil temperatures and salinity. Litter reduced salinity (top 2 cm) in warmer months, from ‘severe’ where only halophytes survive, to ‘moderate’ where growth of non-halophytic species is possible, but at reduced rates. Recruitment was influenced by microsite characteristics including, litter quantities, mounding and row position. Content Type Journal Article Pages 1-13 DOI 10.1007/s11104-011-0850-7 Authors Claire Farrell, School of Plant Biology, Faculty of Natural and Agricultural Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009, Australia Christopher Szota, School of Plant Biology, Faculty of Natural and Agricultural Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009, Australia Richard J. Hobbs, School of Plant Biology, Faculty of Natural and Agricultural Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009, Australia Timothy D. Colmer, School of Plant Biology, Faculty of Natural and Agricultural Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009, Australia Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description:    Warming and elevated atmospheric CO 2 (eCO 2 ) can elicit contrasting responses on different SOM pools, thus to understand the effects of combined factors it is necessary to evaluate individual pools. Over two years, we assessed responses to eCO 2 and warming of SOM pools, their susceptibility to decomposition, and whether these responses were mediated by plant inputs in a semi-arid grassland at the PHACE ( P rairie H eating a nd C O 2 E nrichment) experiment. We used long-term soil incubations and assessed relationships between plant inputs and the responses of the labile and resistant pools. We found strong and contrasting effects of eCO 2 and warming on the labile C pool. In 2008 labile C was increased by eCO 2 and was positively related to plant biomass. In contrast, in 2007 eCO 2 and warming had interactive effects on the labile C, and the pool size was not related to plant biomass. Effects of warming and eCO 2 in this year were consistent withtreatment effects on soil moisture and temperature and their effects on labile C decomposition. The decomposition rate of the resistant C was positively related to indicators of plant C inputs. Our approach demonstrated that SOM pools in this grassland can have early and contrasting responses to climate change factors. The labile C pool in the mixed-grass prairie was highly responsive to eCO 2 and warming but the factors behind such responses were highly dynamic across years. Results suggest that in this grassland the resistant C pool could be negatively affected by increases in plant-production driven available soil C. Content Type Journal Article Pages 1-12 DOI 10.1007/s11104-011-0853-4 Authors Yolima Carrillo, Department of Botany, University of Wyoming, Laramie, WY 82071, USA Elise Pendall, Department of Botany, University of Wyoming, Laramie, WY 82071, USA Feike A. Dijkstra, Faculty of Agriculture, Food and Natural Resources, The University of Sydney, Level 4, Biomedical Building—C81, Australian Technology Park, Eveleigh, NSW 2015, Australia Jack A. Morgan, Rangeland Resources Research Unit, USDA-ARS, Crops Research Laboratory, 1701 Center Ave, Fort Collins, CO 80526, USA Joanne M. Newcomb, Department of Botany, University of Wyoming, Laramie, WY 82071, USA Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description:    Recent studies suggest that phosphatase activity in soil under legumes is higher than under other plants, but whether this is due to plant activity, microbe activity, or a response to altered soil N or P is unclear. I addressed two main questions: (i) do legumes have a higher root phosphomonoesterase (PME) activity than non-legumes?, and (ii) does root PME activity of legumes and non-legumes respond differently to variation in P or N supply? In four greenhouse experiments, I compared PME activity of seven leguminous forbs and nine other herb species (mostly forbs), under various supplies of inorganic P or N. Under low P and high N supply, legumes had on average a 50% or 120% higher PME activity than other forbs (expressed per fresh or dry roots). Legumes were similar or more plastic in their response to gradients of P, but less plastic to gradients of N. Root PME activity did not seem to depend on the presence of nodules, nor on growing in species monocultures or mixtures. On average leguminous forbs do have a higher root PME activity than other forbs, particularly under low inorganic P and N supply. Under higher N supply, the difference between leguminous and non-leguminous forbs becomes smaller, and PME activity of grasses may even be higher than that of legumes. The results help explaining why legumes can become abundant in plant communities on P and N-poor soils. Content Type Journal Article Pages 1-10 DOI 10.1007/s11104-011-0834-7 Authors Harry Olde Venterink, Institute of Integrative Biology, ETH Zurich, Universitätsstrasse 16, 8092 Zurich, Switzerland Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description:    Forest plantations and agroforestry systems with Schizolobium parahyba var. amazonicum have greatly expanded in the Brazilian Amazon, generally as an alternative for reforesting degraded areas. To our knowledge there are no reports of above- and below-ground production in these forest systems. We quantified litter and fine root production in 6-yr old Schizolobium -based plantation forests (monospecific: MON, mixture: MIX, and agroforestry system: AFS) and in ~25-yr old regrowth forest (REG) over 8–12 months. We used litter traps and ingrowth cores to quantify litter and fine root production, respectively. Annual litter production was significantly lower in Schizolobium -based plantations (mean ± standard error, MON = 5.92 ± 0.15, MIX = 6.08 ± 0.13, AFS = 6.63 ± 0.13 Mg ha −1  year −1 ) than in regrowth forest (8.64 ± 0.08 Mg ha −1  year −1 ). Schizolobium -based plantations showed significantly higher litter stock (MON = 7.7 ± 1.0, MIX = 7.4 ± 0.1 Mg ha −1 ) than REG (5.9 ± 1.3 Mg ha −1 ). Total fine root production over an 8-month period was significantly higher in Schizolobium -based plantations (MON = 3.8 ± 0.2, MIX = 3.4 ± 0.2, AFS = 2.7 ± 0.1 Mg ha −1 ) than in REG (1.1 ± 0.03 Mg ha −1 ). Six-yr old Schizolobium -based plantations and ~25-yr old regrowth forests showed comparable rates of litter + fine root production, suggesting that young forest plantations may be an interesting alternative to restore degraded areas due to early reestablishment of organic matter cycling under the studied conditions. Content Type Journal Article Pages 1-10 DOI 10.1007/s11104-011-0857-0 Authors Antonio Kledson Leal Silva, Universidade Federal do Para, Programa de Pos-graduacao em Ciencias Ambientais, Belem, Para, Brazil Steel Silva Vasconcelos, Embrapa Amazonia Oriental, Laboratorio de Ecofisiologia Vegetal, Belem, Para, Brazil Claudio José Reis de Carvalho, Embrapa Amazonia Oriental, Laboratorio de Ecofisiologia Vegetal, Belem, Para, Brazil Iracema Maria Castro Coimbra Cordeiro, Tramontina Belem S.A., Belem, Para, Brazil Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description:    Several studies have shown that soil biotic communities from organically managed fields are more diverse and exhibit higher activity levels compared to conventionally managed fields. The impact of these different soil communities on plant productivity and the provision of soil ecosystem services are, however, still unclear. Here, we test the effects of soil inoculation from each of three organic and three conventional maize fields on maize productivity and nutrient loss during leaching events induced by simulated rain. In particular, we examine whether differences in productivity and nutrient loss are related to the abundance and species composition of arbuscular mycorrhizal (AM) fungi. We hypothesized that soil biota from organically managed fields would improve maize growth and reduce nutrient leaching significantly more than those from conventionally managed fields. In contrast to our hypothesis, we found that plant productivity was negatively affected by soil inoculation, and this effect was stronger with inoculum from organic fields. Plant productivity was inversely correlated with AMF abundance, suggesting that enhanced carbon allocation to AMF is at least in part responsible for plant growth reduction under our experimental conditions. However, soil inoculation did alter the ecological functioning of the system by reducing phosphorus leaching losses after simulated rain. Moreover, these leaching losses were lower with increased hyphal density and were related with abundance of particular AMF types, suggesting that abundance of AMF and their community composition may be useful indicators of phosphorus leaching losses. The results demonstrate that soil communities from different agricultural fields vary in their impact on plant productivity and nutrient leaching losses. The results further indicate that there is a potential tradeoff between positive effects of soil communities on sustainability and negative effects on crop productivity. Content Type Journal Article Pages 1-13 DOI 10.1007/s11104-011-0828-5 Authors Erik Verbruggen, Department of Ecological Science, Faculty of Earth and Life Sciences, VU University Amsterdam, Amsterdam, the Netherlands E. Toby Kiers, Department of Ecological Science, Faculty of Earth and Life Sciences, VU University Amsterdam, Amsterdam, the Netherlands Patrick N. C. Bakelaar, Department of Ecological Science, Faculty of Earth and Life Sciences, VU University Amsterdam, Amsterdam, the Netherlands Wilfred F. M. Röling, Molecular Cell Physiology, Faculty of Earth and Life Sciences, VU University Amsterdam, Amsterdam, the Netherlands Marcel G. A. van der Heijden, Department of Ecological Science, Faculty of Earth and Life Sciences, VU University Amsterdam, Amsterdam, the Netherlands Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description:    For establishing rational farming mechanism, it is essential to know the relative contribution of different geological background and anthropogenic activities to trace elements in agricultural soil. In this paper, 282 surface soil samples were collected based on the different geological background. Five harmful trace elements (As, Cd, Cr, Hg and Pb) were analyzed. The results indicated most of trace elements contents were far beyond the threshold of uncultivated soil background, which indicate anthropogenic input strongly influenced on trace elements in agricultural soil. In addition, correlation analysis showed trace element contents exhibited high relationships with soil pH, C/N and physical clay (〈0.01 mm) ( p  〈 0.05). The principal component analysis showed that the first component included Cd, Cr and Hg, while Pb and As formed the second component. Furthermore, in the agricultural topsoil derived from carbonate rock, the high background values of trace elements and alkaline condition made the enrichments of Cd, Cr and Hg were the most significant. In the agricultural topsoil derived from red residua, the Pb and As contents was the highest values among the soil categories, partly because the type of soil had amount of physical clay (〈0.01 mm). In the agricultural topsoil derived from shale, the pH or physical clay had significant relationship with Cd, Pb, Hg and As ( p  〈 0.01). In the agricultural topsoil derived from sand stone, the acid condition and loose texture might account for the lowest values of Cd, Cr, Pb and As content to some extent. Content Type Journal Article Pages 1-11 DOI 10.1007/s11104-011-0866-z Authors Chenglong Tu, State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550002 China Tengbing He, Agricultural college, Guizhou University, Guiyang, 550001 China Congqiang Liu, State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550002 China Xiaohui Lu, School of Geographic and Environmental Sciences, Guizhou Normal University, Guiyang, 550001 China Yunchao Lang, State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550002 China Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Genes do not form channels Content Type Journal Article Pages 1-3 DOI 10.1007/s11104-011-0872-1 Authors Dev T. Britto, Department of Biological Sciences, University of Toronto, Toronto, ON, Canada M1C 1A4 Herbert J. Kronzucker, Department of Biological Sciences, University of Toronto, Toronto, ON, Canada M1C 1A4 Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description:    This study aims to quantify nitrogen (N) effect on occurrence of perfect rice kernel (PRK) and imperfect grains which includes white-belly rice kernel (WBRK), white-core rice kernel (WCRK), green rice kernel (GRK), opaque rice kernel (ORK), and other imperfect grains (OTHERS). Two-year field experiments involving six japonica rice cultivars and seven N treatments were performed. The structural differences between white-belly and white-core tissues were compared using scanning electron microscope. Averaged over cultivars, grain yield increased progressively with N rate. PRK increased with N rate in 2008, but decreased with increased N rate in 2009. WBRK and WCRK decreased as N rate increased for both years. High N input resulted in higher occurrence of GRK and OTHERS for both years. Most starch granules in white-belly tissues are intact and surrounded by globular protein bodies, with many air spaces between them; while in white-core tissues, starch granules are easily broken into many single granules and no protein bodies are visible. Our results suggest that N has suppressing influence on chalky grains but favorable effect on other imperfect grains, and indicate different mechanism between WBRK and WCRK. Content Type Journal Article Pages 1-12 DOI 10.1007/s11104-011-0861-4 Authors Jiangfang Qiao, College of Agronomy, Nanjing Agricultural University, Nanjing, 210095 China Zhenghui Liu, College of Agronomy, Nanjing Agricultural University, Nanjing, 210095 China Shanyu Deng, College of Agronomy, Nanjing Agricultural University, Nanjing, 210095 China Huifeng Ning, College of Agronomy, Nanjing Agricultural University, Nanjing, 210095 China Xiaoyu Yang, College of Agronomy, Nanjing Agricultural University, Nanjing, 210095 China Zhaomiao Lin, College of Agronomy, Nanjing Agricultural University, Nanjing, 210095 China Ganghua Li, College of Agronomy, Nanjing Agricultural University, Nanjing, 210095 China Qiangsheng Wang, College of Agronomy, Nanjing Agricultural University, Nanjing, 210095 China Shaohua Wang, College of Agronomy, Nanjing Agricultural University, Nanjing, 210095 China Yanfeng Ding, College of Agronomy, Nanjing Agricultural University, Nanjing, 210095 China Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description:    Root hairs are tip-growing extensions from root epidermal cells that play important roles in nutrient uptake and in plant-soil interactions. In this review, we discuss the major environmental, physiological and genetic factors that regulate the differentiation and growth of root hairs in angiosperms. Root hair cells are arranged in a number of different patterns in the root epidermis of different species. In Arabidopsis ( Arabidopsis thaliana L.), a striped pattern of hair and non-hair files is generated by an intercellular gene regulatory network that involves feedback loops and protein movement between neighbouring cells. The growth of root hairs can be broadly divided into an initiation phase, where site selection and bulge formation take place, and an elongation phase. The initiation phase is regulated by different transcription factors, GTPases and cell wall modification enzymes. During the elongation phase root hairs grow by tip growth, a type of polarised cell expansion that is restricted to the growing apex. Root hair elongation is characterized by a strong polarisation of the cytoskeleton, active cell wall modifications and dynamic ion movements. Finally, we discuss the functional and genetic similarities between the root hairs of angiosperms and the rhizoids of bryophytes and ferns. Content Type Journal Article Pages 1-14 DOI 10.1007/s11104-011-0845-4 Authors Sourav Datta, Department of Plant Sciences, University of Oxford, Oxford, OX1 3RB, UK Chul Min Kim, Department of Plant Sciences, University of Oxford, Oxford, OX1 3RB, UK Monica Pernas, Department of Plant Sciences, University of Oxford, Oxford, OX1 3RB, UK Nuno D. Pires, Department of Plant Sciences, University of Oxford, Oxford, OX1 3RB, UK Hélène Proust, Department of Plant Sciences, University of Oxford, Oxford, OX1 3RB, UK Thomas Tam, Department of Plant Sciences, University of Oxford, Oxford, OX1 3RB, UK Priya Vijayakumar, Department of Plant Sciences, University of Oxford, Oxford, OX1 3RB, UK Liam Dolan, Department of Plant Sciences, University of Oxford, Oxford, OX1 3RB, UK Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description:    In the present work a general theoretical framework for coupled dimensionally-heterogeneous partial differential equations is developed. This is done by recasting the variational formulation in terms of coupling interface variables. In such a general setting we analyze existence and uniqueness of solutions for both the continuous problem and its finite dimensional approximation. This approach also allows the development of different iterative substructuring solution methodologies involving dimensionally-homogeneous subproblems. Numerical experiments are carried out to test our theoretical results. Content Type Journal Article Pages 1-37 DOI 10.1007/s00211-011-0387-y Authors Pablo J. Blanco, LNCC, Laboratório Nacional de Computação Científica, Av. Getúlio Vargas 333, Quitandinha, 25651-075 Petrópolis, Brazil Marco Discacciati, MATHICSE, Chair of Modelling and Scientific Computing, Ecole Polytechnique Fédérale de Lausanne, Station 8, CH-1015 Lausanne, Switzerland Alfio Quarteroni, MATHICSE, Chair of Modelling and Scientific Computing, Ecole Polytechnique Fédérale de Lausanne, Station 8, CH-1015 Lausanne, Switzerland Journal Numerische Mathematik Online ISSN 0945-3245 Print ISSN 0029-599X

Description:    In this paper we introduce a generalized Sobolev space by defining a semi-inner product formulated in terms of a vector distributional operator P consisting of finitely or countably many distributional operators P n , which are defined on the dual space of the Schwartz space. The types of operators we consider include not only differential operators, but also more general distributional operators such as pseudo-differential operators. We deduce that a certain appropriate full-space Green function G with respect to L :=  P * T P now becomes a conditionally positive function. In order to support this claim we ensure that the distributional adjoint operator P * of P is well-defined in the distributional sense. Under sufficient conditions, the native space (reproducing-kernel Hilbert space) associated with the Green function G can be embedded into or even be equivalent to a generalized Sobolev space. As an application, we take linear combinations of translates of the Green function with possibly added polynomial terms and construct a multivariate minimum-norm interpolant s f , X to data values sampled from an unknown generalized Sobolev function f at data sites located in some set X Ì \mathbb R d . We provide several examples, such as Matérn kernels or Gaussian kernels, that illustrate how many reproducing-kernel Hilbert spaces of well-known reproducing kernels are equivalent to a generalized Sobolev space. These examples further illustrate how we can rescale the Sobolev spaces by the vector distributional operator P . Introducing the notion of scale as part of the definition of a generalized Sobolev space may help us to choose the “best” kernel function for kernel-based approximation methods. Content Type Journal Article Pages 1-27 DOI 10.1007/s00211-011-0391-2 Authors Gregory E. Fasshauer, Department of Applied Mathematics, Illinois Institute of Technology, Chicago, IL 60616, USA Qi Ye, Department of Applied Mathematics, Illinois Institute of Technology, Chicago, IL 60616, USA Journal Numerische Mathematik Online ISSN 0945-3245 Print ISSN 0029-599X

Description:    We are concerned with the inverse problem for an eikonal equation of determining the speed function using observations of the arrival time on a fixed surface. This is formulated as an optimisation problem for a quadratic functional with the state equation being the eikonal equation coupled to the so-called Soner boundary condition. The state equation is discretised by a suitable finite difference scheme for which we obtain existence, uniqueness and an error bound. We set up an approximate optimisation problem and show that a subsequence of the discrete mimina converges to a solution of the continuous optimisation problem as the mesh size goes to zero. The derivative of the discrete functional is calculated with the help of an adjoint equation which can be solved efficiently by using fast marching techniques. Finally we describe some numerical results. Content Type Journal Article Pages 1-25 DOI 10.1007/s00211-011-0386-z Authors Klaus Deckelnick, Institut für Analysis und Numerik, Otto-von-Guericke-Universität Magdeburg, Universitätsplatz 2, 39106 Magdeburg, Germany Charles M. Elliott, Mathematics Institute, University of Warwick, Coventry, CV4 7AL UK Vanessa Styles, Department of Mathematics, University of Sussex, Brighton, BN1 9RF UK Journal Numerische Mathematik Online ISSN 0945-3245 Print ISSN 0029-599X

Description:    We present a new model unifying state-of-the-art descriptions of microbial processes for denitrification, nitrification and decomposition of soil organic matter. The model is of medium complexity, filling a gap between simplistic model approaches with low predictive power and complex models, which are difficult to verify experimentally. The model M icrobial C arbon and N itrogen T urnover in soils (MiCNiT) is written in Ansi C++ and embedded into a modelling framework (MoBiLE) that provides initial conditions and accompanying ecosystem processes such as N uptake by plants, litterfall, soil water and soil temperature with established model approaches. The MiCNiT model explicitly calculates decomposition, dynamics of microbial biomass, denitrification, autotrophic and heterotrophic nitrification, applying the microbial activity concept, as well as transport of gases and solutes between anaerobic and aerobic soil fractions and through the soil profile. The model was tested against N 2 O and CO 2 emission as well as C and N pool data from the Höglwald Forest, Germany. Due to a detailed description of the soil biochemistry and gaseous transfers, MiCNiT is capable of simulating soil air NO, N 2 O and N 2 concentrations and the net exchange of these gases at the soil-atmosphere interface, including a possible net uptake of N 2 O by soils. Content Type Journal Article Pages 1-34 DOI 10.1007/s11104-011-0821-z Authors Sergey Blagodatsky, Karlsruhe Institute of Technology, Institute for Meteorology and Climate Research, Atmospheric Environmental Research (IMK-IFU), Kreuzeckbahnstr. 19, 82467 Garmisch-Partenkirchen, Germany Rüdiger Grote, Karlsruhe Institute of Technology, Institute for Meteorology and Climate Research, Atmospheric Environmental Research (IMK-IFU), Kreuzeckbahnstr. 19, 82467 Garmisch-Partenkirchen, Germany Ralf Kiese, Karlsruhe Institute of Technology, Institute for Meteorology and Climate Research, Atmospheric Environmental Research (IMK-IFU), Kreuzeckbahnstr. 19, 82467 Garmisch-Partenkirchen, Germany Christian Werner, Karlsruhe Institute of Technology, Institute for Meteorology and Climate Research, Atmospheric Environmental Research (IMK-IFU), Kreuzeckbahnstr. 19, 82467 Garmisch-Partenkirchen, Germany Klaus Butterbach-Bahl, Karlsruhe Institute of Technology, Institute for Meteorology and Climate Research, Atmospheric Environmental Research (IMK-IFU), Kreuzeckbahnstr. 19, 82467 Garmisch-Partenkirchen, Germany Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description:    Changes in precipitation patterns and N cycling across the globe are likely to affect ecosystem primary productivity and CO 2 exchanges, especially in arid and semi-arid grasslands. To evaluate the effects of water and N availability on ecosystem CO 2 fluxes, we conducted a manipulative field experiment with water and N addition in a temperate semiarid steppe in 2006 and 2007 with remarkably different amount of natural precipitation. For each growing season (June–September), water (15 mm) was added about every 2 weeks, which summed up to about 120 mm year −1 . N (as urea) was added at a rate of 6.96 g N m −2 every month during the same period. Variations of the growing-season CO 2 fluxes, including net ecosystem exchange (NEE), gross ecosystem photosynthesis (GEP) and ecosystem respiration (ER) were examined. Net carbon uptake was found in all treatments over the growing season in both years, with the growing season average NEE ranging from −1.27 to −5.59 μmol m −2  s −1 . During two growing seasons, water and N addition significantly increased NEE (+42% and +30% in 2006 and 2007, respectively), because greater stimulation of GEP than ER. Net primary productivity, especially grass biomass, correlated closely with variation in GEP and ER. Precipitation (and thus soil moisture) regulated seasonal and inter-annual variations in GEP and ER, and subsequently NEE. Moreover, both water and N addition effects depended greatly on the initial water condition in this temperate semiarid steppe. Content Type Journal Article Pages 1-14 DOI 10.1007/s11104-011-0864-1 Authors Liming Yan, State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, No. 20 Nanxincun, Xiangshan, Beijing, 100093 China Shiping Chen, 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 Guanghui Lin, 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:    Glyphosate tolerance by Clitoria ternatea , Neonotonia wightii and Amaranthus hybridus was studied in whole plants from Mexico. Experiments in a controlled growth chamber showed both legumes to be highly tolerant of glyphosate, with and ED 50 values of 600.18 g ae ha –1 for C. ternatea and 362.94 g ae ha –1 for N. wightii . On the other hand, A. hybridus was highly susceptible to the herbicide (ED 50  = 42.22 g ae ha –1 ). Shikimate accumulation peaked 96 h after treatment in the tolerant plants and the susceptible weed under 500 g ae ha –1 glyphosate. The shikimic acid content of whole leaves was 4.0 and 5.0 times higher in the susceptible weed than in N. wightii and C. ternatea , respectively. 14 C-glyphosate absorption and translocation tests showed A. hybridus to absorb 30% more herbicide than the legumes 24 h after glyphosate foliar application. 14 C-glyphosate translocation as measured by quantified autoradiography revealed increased translocation of the herbicide to untreated leaves and roots in A. hybridus relative to the two legumes. The cuticular surface of A. hybridus exhibited very low wax coverage relative to the epicuticular surface of N. wightii and, especially, C. ternatea . No significant degradation of glyphosate to aminomethylphosphonic acid and glyoxylate metabolites was detected among the tolerant leguminous plants or the susceptible weed population. These results indicate that the high glyphosate tolerance of Clitoria ternatea and Neonotonia wightii is mainly a result of poor penetration and translocation of the herbicide to apical growing points in their plants. Content Type Journal Article Pages 1-10 DOI 10.1007/s11104-011-0840-9 Authors Hugo Cruz-Hipolito, Department of Agricultural Chemistry and Edaphology, University of Córdoba, Córdoba, Spain Antonia Rojano-Delgado, Department of Agricultural Chemistry and Edaphology, University of Córdoba, Córdoba, Spain José A. Domínguez-Valenzuela, Department of Agricultural Parasitology, Chapingo Autonomous University, Chapingo, State of Mexico, Mexico Antonio Heredia, Department of Molecular Biology and Biochemistry, University of Málaga, Málaga, Spain María Dolores Luque de Castro, Department of Analytical Chemistry, Campus of Rabanales, University of Córdoba, Córdoba, Spain Rafael De Prado, Department of Agricultural Chemistry and Edaphology, University of Córdoba, Córdoba, Spain Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description:    Tillage effects on soil nitrification kinetics at the aggregate scale were studied for a subtropical rice soil. Soil samples were separated into large aggregates (〉2.0 mm), macro-aggregates (2.0–0.25 mm), micro-aggregates (0.25–0.053 mm) and silt + clay fractions (〈0.053 mm) by wet-sieving. The net nitrification process was simulated by a zero- and first kinetics model. Conventional tillage (CT) increased the proportion of the silt + clay fraction by 60% and decreased large-aggregates by 35% compared to ridge with no-till (RNT). Regression analysis showed that the time-dependent kinetics of net nitrification were best fitted by a zero-order model for the large-aggregates and silt + clay fraction but a first-order kinetic model for macro- and microaggregates and whole soil, regardless of tillage regime. Both potential nitrification rates ( V p ) and net nitrification rates ( V a ) were higher for macroaggregates than microaggregates. The potential nitrification ( N p ) for whole soil under RNT was 38.7% higher than CT. The V p and V a for whole soil was 88.5% and 64.7% higher under RNT than CT, respectively. Although nitrification was stimulated under RNT, the kinetics model of nitrification was not affected by tillage. This inferred that the interaction between substrates and enzymes involved in nitrification associated with aggregates was not altered by tillage. For this soil, nitrifying microorganisms were mainly associated with macro- and microaggregates rather than large-aggregates and silt + clay fractions. Content Type Journal Article Pages 1-8 DOI 10.1007/s11104-011-0849-0 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 People’s Republic of China Xiuli Shi, College of Horticulture and Landscape Architecture, 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 People’s Republic of China Alan L. Wright, Everglades Research & Education Center, University of Florida, Belle Glade, FL 33430, USA Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description:    Members of the genus Burkholderia are highly versatile bacteria that can be beneficial as well as pathogenic for their eukaryotic hosts. Furthermore, many strains exhibit a remarkable biotechnological potential. To study the ecosystem function and lifestyle of B. terricola , we analysed the interactions with plants and survival in soil as well as the mechanisms behind it. We used a combination of in vitro and ad planta assays to study Burkholderia -plant interaction and assess the role of poly-β-hydroxybutyrate (PHB). Additionally, DsRed-labelled bacteria were analysed by confocal laser scanning microscopy (CLSM) to study root colonisation. B. terricola ZR2-12 treatment resulted in enhanced growth of sugar beet plants with a more than doubled biomass relative to the non-treated control. The strain was a remarkable good root coloniser, which was found in rhizosphere as well as endorhiza of sugar beet up to 10 log 10 CFU g −1 . Using CLSM, we observed that ZR2-12 cells form large micro-colonies along the apoplastic spaces of the root. Xylem vessels were colonised by smaller aggregates and single cells, whereas in root tips mainly single cells were present. The colonisation patterns differed strongly between older and younger parts of the roots. PHB production of ZR2-12 (up to 70% (w/w) of cell dry mass) provided a competitive advantage for rhizosphere colonisation. B. terricola ZR2-12 belongs to the plant-associated Burkholderia cluster with biotechnological potential due to its excellent root colonisation and plant growth promotion. Content Type Journal Article Pages 1-12 DOI 10.1007/s11104-011-0833-8 Authors Ilona Gasser, Institute of Environmental Biotechnology, Graz University of Technology, Graz, Austria Massimiliano Cardinale, Institute of Environmental Biotechnology, Graz University of Technology, Graz, Austria Henry Müller, Institute of Environmental Biotechnology, Graz University of Technology, Graz, Austria Stefanie Heller, Institute of Plant Biology, University of Zurich, Zurich, Switzerland Leo Eberl, Institute of Plant Biology, University of Zurich, Zurich, Switzerland Nicole Lindenkamp, Institut für Molekulare Mikrobiologie und Biotechnologie, Westfälische Wilhelms-Universität Münster, Münster, Germany Chlud Kaddor, Institut für Molekulare Mikrobiologie und Biotechnologie, Westfälische Wilhelms-Universität Münster, Münster, Germany Alexander Steinbüchel, Institut für Molekulare Mikrobiologie und Biotechnologie, Westfälische Wilhelms-Universität Münster, Münster, Germany Gabriele Berg, Institute of Environmental Biotechnology, Graz University of Technology, Graz, Austria Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description:    Many rangelands around the world are degraded by severe overgrazing with resulting loss of nutrients and reduced productivity. However, grazing may also increase nutrient cycling and enhance ecosystem productivity. The aim of this study was to determine effects of grazing on availability of nitrogen (N), sources of N utilized by plants and cycling and distribution of N at a low-alpine site, Southern Norway. The study was part of a sheep grazing experiment with three density levels of sheep (no sheep, 25 km −2 and 80 km −2 ) since 2001. The N-content of plants was determined in June 2008, August 2008 and August 2009. Indirect effects of herbivory on sources of N and N-cycling were assessed by δ 15 N natural abundance and the system’s distribution of added 15 NH 4 -N. We found little evidence for grazing induced effects on availability, sources or cycling of N based on N content of plants and δ 15 N natural abundance. The organic soil horizon was the largest sink for the added 15 NH 4 -N. Proportional tracer recoveries and tracer enrichments indicate a somewhat greater N cycling at grazed than at non-grazed sites. We conclude that the experimental levels of grazing have limited impact on distribution and cycling of N and thus represent sustainable ecosystem management in terms of N dynamics in the long-term. Content Type Journal Article Pages 1-14 DOI 10.1007/s11104-011-0847-2 Authors Vegard Martinsen, Department of Plant and Environmental Sciences, Norwegian University of Life Sciences, P.O. Box 5003, NO-1432 Ås, Norway Gunnar Austrheim, Museum of Natural History and Archaeology, Section of Natural History, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway Atle Mysterud, Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biology, University of Oslo, P.O. Box 1066, Blindern, NO-0316 Oslo, Norway Jan Mulder, Department of Plant and Environmental Sciences, Norwegian University of Life Sciences, P.O. Box 5003, NO-1432 Ås, Norway Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description:    Increasing iron (Fe) concentration in food crops is an important global challenge due to high incidence of Fe deficiency in human populations. Evidence is available showing that nitrogen (N) fertilization increases Fe concentration in wheat grain. This positive impact of N on grain Fe was, however, not studied under varied soil and foliar applications of Fe. Greenhouse experiments were conducted to investigate a role of soil- and foliar-applied Fe fertilizers in improving shoot and grain Fe concentration in durum wheat ( Triticum durum ) grown under increasing N supply as Ca-nitrate. Additionally, an effect of foliar Fe fertilizers on grain Fe was tested with and without urea in the spray solution. Application of various soil or foliar Fe fertilizers had either a little positive effect or remained ineffective on shoot or grain Fe. By contrast, at a given Fe treatment, raising N supply substantially enhanced shoot and grain concentrations of Fe and Zn. Improving N status of plants from low to sufficient resulted in a 3-fold increase in shoot Fe content (e.g., total Fe accumulated), whereas this increase was only 42% for total shoot dry weight. Inclusion of urea in foliar Fe fertilizers had a positive impact on grain Fe concentration. Nitrogen fertilization represents an important agronomic practice in increasing grain Fe. Therefore, the plant N status deserves special attention in biofortification of food crops with Fe. Content Type Journal Article Pages 1-11 DOI 10.1007/s11104-011-0863-2 Authors Seher Bahar Aciksoz, Faculty of Engineering and Natural Sciences, Sabanci University, 34956 Istanbul, Turkey Atilla Yazici, Faculty of Engineering and Natural Sciences, Sabanci University, 34956 Istanbul, Turkey Levent Ozturk, Faculty of Engineering and Natural Sciences, Sabanci University, 34956 Istanbul, Turkey Ismail 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:    Boron (B) is essential for the normal growth and development of oilseed rape. To gain better insight into the metabolic processes of Brassica napus in response to B starvation, a time course proteomics analysis of roots under conditions of hydroponic cultivation was carried out. Forty-six differentially expressed proteins were identified by MALDI-TOF/TOF MS. These proteins were classified into the following functional categories: carbohydrate and energy metabolism, stress response, signaling and regulation, cell wall, protein process, amino acid and fatty acid metabolism, nucleic acid metabolism. In general, the energy metabolism pathway and certain biosynthesis pathways were maintained at a relatively low level, while signaling, regulation and stress response pathways were dramatically induced in the absence of B. Eight genes were selected for qPCR analysis to detect the relationships among protein and gene expression patterns. Furthermore, analyses of lipid peroxidation and glutathione reductase activity revealed that oxidative damage was induced and the antioxidative system was activated under conditions of B deficiency. These results suggest that carbon flux is a putative modulating process that controls the response to B deficiency stress, and a stable cell wall structure, resistance to oxidative damage and a complex signaling network may contribute to the tolerance to B deficiency. Content Type Journal Article Pages 1-16 DOI 10.1007/s11104-011-0838-3 Authors Zhenhua Wang, National Key Laboratory of Crop Genetic Improvement, and Microelement Research Centre, Huazhong Agricultural University, Wuhan, 430070 China Zhifang Wang, National Key Laboratory of Crop Genetic Improvement, and Microelement Research Centre, Huazhong Agricultural University, Wuhan, 430070 China Shuisen Chen, National Key Laboratory of Crop Genetic Improvement, and Microelement Research Centre, Huazhong Agricultural University, Wuhan, 430070 China Lei Shi, National Key Laboratory of Crop Genetic Improvement, and Microelement Research Centre, Huazhong Agricultural University, Wuhan, 430070 China Fangsen Xu, National Key Laboratory of Crop Genetic Improvement, and Microelement Research Centre, Huazhong Agricultural University, Wuhan, 430070 China Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description:    The tissue structure of a bamboo stem (culm) differs from that of woody species, exhibiting a large cavity in the internode surrounded by a cortex with high silica concentration. Thus, to obtain an accurate estimation of the necromass, as well as carbon (C) and nitrogen (N) stocks in dead bamboo culms, we examined the basic characteristics of culm structure as well as the C and N concentrations of decomposing culms of Phyllostachys bambusoides and P. heterocycla . We collected dead culms of the two bamboo species from 15 bamboo stands in central and southwestern Japan, and analyzed the relationship between the ratio of wall volume to culm disk volume and culm diameter, as well as the changes of C and N concentrations in dead culms with wall density, which can be used as an indicator of the degree of decomposition. The ratio of wall volume to culm volume tended to decrease with increasing culm diameter for both species. The C concentration did not change, but the N concentration increased with decreasing wall density. The wall density was related to the C/N ratio, which is a chemical parameter of the degree of decomposition. The culm structure should be considered when estimating culm density. The mean C concentration can be used for estimating the C stock of decomposing culms irrespective of decomposition level. N concentration, however, should be determined according to decomposition level for N stock estimation. Content Type Journal Article Pages 1-10 DOI 10.1007/s11104-011-0844-5 Authors Shin Ugawa, Department of Forest Site Environment, Forestry and Forest Products Research Institute, Matsunosato 1, Tsukuba-shi, Ibaraki, 305-8687 Japan Satoru Miura, Department of Forest Site Environment, Forestry and Forest Products Research Institute, Matsunosato 1, Tsukuba-shi, Ibaraki, 305-8687 Japan Yojiro Matsuura, Department of Forest Site Environment, Forestry and Forest Products Research Institute, Matsunosato 1, Tsukuba-shi, Ibaraki, 305-8687 Japan Masamichi Takahashi, Department of Research Planning and Coordination, Forestry and Forest Products Research Institute, Matsunosato 1, Tsukuba-shi, Ibaraki, 305-8687 Japan Shinji Kaneko, Department of Forest Site Environment, Forestry and Forest Products Research Institute, Matsunosato 1, Tsukuba-shi, Ibaraki, 305-8687 Japan Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description:    Soil respiration (R S ) and soil carbon stocks, as well as stand properties were investigated in a warm-temperate oak chronosequence in order to understand the age effect on soil CO 2 efflux. The chronosequence consisted of three 40-year-old, 48-year-old, 80-year-old, and 143-year-old oak stands, respectively. R S measurements were conducted using a Li-8100 soil CO 2 flux system from October 2008 to October 2009. Temporal variations of R S of all the four forests largely depended on soil temperature of 5 cm depth (T 5 ) (R 2  = 0.738–0.825). The mean R S for 40-year-old, 48-year-old, 80-year-old, and 143-year-old forests were 2.37, 2.59, 2.99, and 3.32 μmol CO 2 m -2  s -1 respectively. Both top soil organic carbon (SOC) and light fraction organic carbon (LFOC) stocks were significantly correlated to R S variation, while only significant different LFOC among stands was found. This indicated that cumulated labile organic carbon was a better indicator on R S variation, which was further illustrated by a better relationship between R 10 and LFOC than that of R 10 and SOC. We found that the variation of mean R S among stands was well correlated with basal area (BA). Marginal correlation between R S and fine root biomass (FR) demonstrated the relationship between R S and belowground metabolism. We also found total porosity (TP) negatively influenced the mean R S and this negative effect may mainly be attributed to the capillary porosity (CP). Forest growth and yield could be contributed to R S variation among stands. Forest succession also changed soil labile carbon stock and soil physical properties that influenced the CO 2 efflux. Content Type Journal Article Pages 1-11 DOI 10.1007/s11104-011-0842-7 Authors Junwei Luan, Key Laboratory of Forest Ecology and Environment, China’s State Forestry Administration; The Research Institute of Forest Ecology, Environment and Protection, Chinese Academy of Forestry, Beijing, 100091 People’s Republic of China Shirong Liu, Key Laboratory of Forest Ecology and Environment, China’s State Forestry Administration; The Research Institute of Forest Ecology, Environment and Protection, Chinese Academy of Forestry, Beijing, 100091 People’s Republic of China Xueling Zhu, Baotianman Natural Reserve Administration, Neixiang, Henan 474350, People’s Republic of China Jingxin Wang, Division of Forestry and Natural Resources, West Virginia University, Morgantown, WV 26506, USA Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description:    Little is known about the soils that support agriculture in Tibet. The aim of this paper is to investigate the physical and chemical properties of Tibet’s agricultural soils, the nutritional status of wheat ( Triticum aestivum L.) and barley ( Hordeum vulgare L.) crops, and the sustainability of current soil management practices. Physical descriptions of Tibet’s agricultural soils were based on soil pits dug at three locations across Tibet’s agricultural zone. Chemical analyses were conducted on soils from seven sites across the zone. Nutritional constraints to agriculture were identified through leaf tissue tests on wheat and barley crops from 23 fields. These results, combined with published information on farm inputs and yields, provided insight into the sustainability of current nutrient practice. Soils were found to be silty or sandy clay loams with alkaline reaction, low organic content and low K and Zn status. Leaf analysis revealed one third to one half of cereal crops were marginal or deficient for K, Zn and Mg. Most farmers export grain and import only nitrogenous and phosphatic fertilizers leading to a nutrient imbalance. A balanced fertilizer program is required to halt nutrient depletion and increase grain production. Reduced tillage and crop residue retention are needed to improve soil health. Content Type Journal Article Pages 1-11 DOI 10.1007/s11104-011-0859-y Authors Nicholas G. Paltridge, School of Agriculture Food and Wine, The University of Adelaide, PMB1, Glen Osmond, SA 5064, Australia Samantha P. P. Grover, Global Change Processes, Landcare Research, PO Box 40, Lincoln, 7640 New Zealand Liu Gouyi, Tibet Agricultural Research Institute, Lhasa, Tibet Autonomous Region, People’s Republic of China Jin Tao, Tibet Agricultural Research Institute, Lhasa, Tibet Autonomous Region, People’s Republic of China Murray J. Unkovich, School of Agriculture Food and Wine, The University of Adelaide, PMB1, Glen Osmond, SA 5064, Australia Nyima Tashi, Tibet Agricultural Research Institute, Lhasa, Tibet Autonomous Region, People’s Republic of China David R. Coventry, School of Agriculture Food and Wine, The University of Adelaide, PMB1, Glen Osmond, SA 5064, Australia Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description:    Symbiotic relationships with microbes may influence how plants respond to environmental change. Here, we investigated how fungal endophyte infection affected the growth of a native grass under altered water and nutrient availability. In a two-month field experiment, we compared the performance of endophyte-infected (EI) and endophyte-free (EF) Achnatherum sibiricum subjected to four treatments comprised of a factorial combination of two levels of water availability and two levels of fertilization. The greatest benefits of endophyte infection occurred in the well-watered fertilized treatment. With reduced water and/or nutrient availability, the benefits declined. EI plants subjected to drought and fertilization had higher root:shoot ratios and allocated more nitrogen to photosynthetic machinery and thus had a higher net photosynthetic rate than EF counterparts. In the well-watered unfertilized treatment, EF plants allocated more nutrients to photosynthetic machinery, while EI plants allocated more resources to defense. Thus EI plants were superior to EF plants in terms of nutrient conservation. In the drought unfertilized treatment, no significant difference occurred between EI and EF plants. Our results support the idea that the endophyte-grass interactions are dependent on available resources. However, we did not find a clear cost of endophyte infection. For A. sibiricum , fertilizer addition resulted in greater benefits of the symbiosis for plant growth, but this advantage decreased under drought. Content Type Journal Article Pages 1-11 DOI 10.1007/s11104-011-0824-9 Authors An Zhi Ren, College of Life Sciences, Nankai University, Tianjin, 300071 People’s Republic of China Xia Li, College of Life Sciences, Nankai University, Tianjin, 300071 People’s Republic of China Rong Han, College of Life Sciences, Nankai University, Tianjin, 300071 People’s Republic of China Li Jia Yin, College of Life Sciences, Nankai University, Tianjin, 300071 People’s Republic of China Mao Ying Wei, College of Life Sciences, Nankai University, Tianjin, 300071 People’s Republic of China Yu Bao Gao, College of Life Sciences, Nankai University, Tianjin, 300071 People’s Republic of China Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description:    In this paper we construct polynomial lattice rules which have, in some sense, small gain coefficients using a component-by-component approach. The gain coefficients, as introduced by Owen, indicate to what degree the method improves upon Monte Carlo. We show that the variance of an estimator based on a scrambled polynomial lattice rule constructed component-by-component decays at a rate of N −(2 α +1)+ δ , for all δ  〉 0, assuming that the function under consideration has bounded variation of order α for some 0 〈 α ≤ 1, and where N denotes the number of quadrature points. An analogous result is obtained for Korobov polynomial lattice rules. It is also established that these rules are almost optimal for the function space considered in this paper. Furthermore, we discuss the implementation of the component-by-component approach and show how to reduce the computational cost associated with it. Finally, we present numerical results comparing scrambled polynomial lattice rules and scrambled digital nets. Content Type Journal Article Pages 1-27 DOI 10.1007/s00211-011-0385-0 Authors Jan Baldeaux, School of Mathematics, University of New South Wales, Sydney, 2052 Australia Josef Dick, School of Mathematics, University of New South Wales, Sydney, 2052 Australia Journal Numerische Mathematik Online ISSN 0945-3245 Print ISSN 0029-599X

Description:    We explored the relationship between soil processes, estimated through soil respiration ( R soil ), and the spatial variation in forest structure, assessed through the distribution of tree size, in order to understand the determinism of spatial variations in R soil in a tropical forest. The influence of tree size was examined using an index ( I c ) calculated for each tree as a function of (1) the trunk cross section area and (2) the distance from the measurement point. We investigated the relationships between I c and litterfall, root mass and R soil , respectively. Strong significant relationships were found between I c and both litterfall and root mass. R soil showed a large range of variations over the 1-ha experimental plot, from 1.5 to 12.6 g C m −2 d −1 . The best relationship between I c and R soil only explained 17% of the spatial variation in R soil . These results support the assumption that local spatial patterns in litter production and root mass depend on tree distribution in tropical forests. Our study also emphasizes the modest contribution of tree size distribution–which is mainly influenced by the presence of the biggest trees (among the large range size of the inventoried trees greater than 10 cm diameter at 1.30 m above ground level or at 0.5 m above the buttresses)–in explaining spatial variations in R soil . Content Type Journal Article Pages 1-11 DOI 10.1007/s11104-011-0848-1 Authors Laëtitia Bréchet, INRA, UMR Ecologie des Forêts de Guyane, Campus Agronomique, BP 709, 97387 Kourou cedex, French Guiana Stéphane Ponton, INRA, UMR Ecologie des Forêts de Guyane, Campus Agronomique, BP 709, 97387 Kourou cedex, French Guiana Tancrède Alméras, INRA, UMR Ecologie des Forêts de Guyane, Campus Agronomique, BP 709, 97387 Kourou cedex, French Guiana Damien Bonal, INRA, UMR Ecologie des Forêts de Guyane, Campus Agronomique, BP 709, 97387 Kourou cedex, French Guiana Daniel Epron, INRA, UMR 1137, Ecologie et Ecophysiologie Forestières, Centre de Nancy, 54280 Champenoux, France Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description:    Xiphinema index is the most aggressive root parasite affecting vines in Chile, controlled mainly chemically. The aim of this study was to identify rhizobacteria in grapevine roots growing in infested soils and to determine if some of these affect the parasitism caused by the nematode. Rhizobacteria of ungrafted grapevine cultivars from 11 vineyards were isolated using TSBA and identified with FAMEs analysis. The antagonistic effect to X. index of those from soils 1 to 4 was assessed in 500 ml pots treating 2 months old in vitro plants with a bacterial suspension containing 1 × 10 6 c.f.u./ml and 400 nematodes, determining after 4 months growth nematode populations and root damages. Also culture filtrates were assessed. 400 isolates in 25 genera were obtained from the 11 vineyards. The most frequent species were Pseudomonas putida (35.1%), Escherichia coli (7.6%) and Pseudomonas fluorescens (6.1%). Isolates of soils 1 to 4, show that Bacillus megaterium, B. brevis, Pseudomonas corrugata, P. savastanoi, Stenotrophomonas maltophilia and Serratia plymuthica reduced root damage and suppressed populations, meanwhile strains of B. brevis and Comamonas acidovorans increased plant growth but did not control nematodes. It is concluded that these isolates may be useful in biological control programmes in vineyards. Content Type Journal Article Pages 1-13 DOI 10.1007/s11104-011-0851-6 Authors Erwin Aballay, Department of Crop Protection, Faculty of Agronomical Sciences, University of Chile, P.O. Box 1004, Santiago, Chile Anna Mårtensson, Department of Soil and Environment, Swedish University of Agricultural Sciences, Box 7014, SE- 750 07 Uppsala, Sweden Paula Persson, Department of Crop Production Ecology, Swedish University of Agricultural Sciences, Box 7043, SE- 750 07 Uppsala, Sweden Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description:    Since little is known about how the Mediterranean Basin ecosystems are affected by nitrogen deposition, we aimed to understand the use of nitrogen by distinct plant functional groups (PFG: summer semi-deciduous and evergreen sclerophylls) present in the Mediterranean maquis in order to assess which may be more affected by changes in nitrogen availability. The availability of soil inorganic nitrogen, leaf nitrate concentrations and nitrate reductase activity (in vivo and in vitro) were measured during the year in three plant species from each PFG. The patterns of in vitro NRA along the shoot and through the day were also determined. Although summer semi deciduous species occupied soil patches richer in nitrate, their leaf NRA were significantly lower than that of evergreen sclerophylls species. The pattern of nitrate and ammonium availabilities along the year also distinguished the PFG. Results show that each PFG is composed of a number of physiologically similar species. Patterns of NRA varied according to the PFG, which may represent distinct specializations of co-occurring species to access nitrogen. Therefore, the NRA can be used as an indicator of the nitrate availability taking into consideration the time of the year, the plant species and its PFG. Content Type Journal Article Pages 1-14 DOI 10.1007/s11104-011-0856-1 Authors Teresa Dias, Faculdade de Ciências, Centro de Biologia Ambiental (CBA), Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal Domingos Neto, Faculdade de Ciências, Centro de Biologia Ambiental (CBA), Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal Maria Amélia Martins-Loução, Faculdade de Ciências, Centro de Biologia Ambiental (CBA), Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal Lucy Sheppard, Centre of Ecology and Hydrology (CEH), Bush Estate, Penicuik, EH26 OQB UK Cristina Cruz, Faculdade de Ciências, Centro de Biologia Ambiental (CBA), Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description:    Determining which kinds of roots are likely to be consumed by root herbivores may improve our understanding of the mechanistic control on fine root dynamics. Here, we tested the hypothesis that root herbivores prefer to consume the distal lower order roots in their branching networks. Insecticide was applied to soil to quantify effects of root herbivores on root biomass and production in the first five orders (the distal roots numbered as first-order) in Fraxinus mandshurica and Larix gmelinii plantations from May 2008 to July 2009. Root morphology, chemistry, anatomy and physiology were measured simultaneously across branching orders. Among the first five order roots, significant consumptions by herbivores were found only for the two distal lower order roots throughout growing seasons, with 62% of biomass and 57% of production for F. mandshurica , and 71% and 79% for L. gmelinii , respectively. Our results suggest that the distal lower order roots are more palatable and attractive to root herbivores in both plantations, probably because they have higher tissue N, greater respiration rates and lower cellulose. Thus, overlooking herbivore consumption may lead to large underestimation in root biomass and production, which are critical in determining C budget and nutrient cycles in forest ecosystems. Content Type Journal Article Pages 1-11 DOI 10.1007/s11104-011-0854-3 Authors Yue Sun, Key Laboratory of Forest Tree Genetic Improvement and Biotechnology, Ministry of Education, Northeast Forestry University, Harbin, 150040 China Jiacun Gu, Key Laboratory of Forest Tree Genetic Improvement and Biotechnology, Ministry of Education, Northeast Forestry University, Harbin, 150040 China Haifeng Zhuang, Key Laboratory of Forest Tree Genetic Improvement and Biotechnology, Ministry of Education, Northeast Forestry University, Harbin, 150040 China Dali Guo, Department of Ecology, College of Urban and Environmental Sciences, Peking University, Beijing, 100871 China Zhengquan Wang, Key Laboratory of Forest Tree Genetic Improvement and Biotechnology, Ministry of Education, Northeast Forestry University, Harbin, 150040 China Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description:    Salt stress is one of the major abiotic stresses limiting crop growth and productivity. This work investigated the potential of five ST isolates of Trichoderma harzianum (Th-13, Th-14, Th-19, Th-33 and Th-50) applied through seed biopriming in reducing the detrimental effects of salinity stress on wheat ( Triticum aestivum L.). Growth, physiological and biochemical parameters were studied to characterize salt tolerance. One factor was treatments (T1, T2, T3, T4, T5 and T6) and second factor was four levels of salt stress viz., 0, 2, 4 and 6 dsm −1 . In germination test, most of the isolates (Th-14, Th-19 and Th-13) were effective in improving germination percentage and reducing RPG during salinity stress. Seedlings raised from ST Trichoderma isolates had significantly higher root and shoot lengths, CC and MSI than control at all stress levels. The treatments Th-14, Th-19 and Th-13 showed lower accumulation of MDA content whereas proline content and phenolics were higher in treated plants under both non-saline and saline conditions. Highest MDA content was observed in control at salt stress level of 6 dSm −1 . It is concluded that seed biopriming with different salinity tolerant isolates of Trichoderma reduced severity of the effects of salinity though the amelioration was better in Th-14 under present experimental material and conditions. Content Type Journal Article Pages 1-14 DOI 10.1007/s11104-011-0858-z Authors Laxmi Rawat, Center of Advance Faculty Training, Department of Plant Pathology, College of Agriculture, G.B. Pant University of Agriculture & Technology, Pantnagar, 263 145 Uttarakhand, India Y. Singh, Center of Advance Faculty Training, Department of Plant Pathology, College of Agriculture, G.B. Pant University of Agriculture & Technology, Pantnagar, 263 145 Uttarakhand, India N. Shukla, Center of Advance Faculty Training, Department of Plant Pathology, College of Agriculture, G.B. Pant University of Agriculture & Technology, Pantnagar, 263 145 Uttarakhand, India J. Kumar, Center of Advance Faculty Training, Department of Plant Pathology, College of Agriculture, G.B. Pant University of Agriculture & Technology, Pantnagar, 263 145 Uttarakhand, India Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description:    This study examined the impact of plants on acid sulphate soils with the aim of determining whether plants are able to reduce acid production. The study was conducted with clayey acid sulphate soil under controlled conditions with treatments lasting up to 24 weeks and measurements made in the top 0–60 mm of soil. pH profiles in the soil were strongly dependent on soil moisture and the pattern of irrigation. When bare soil was allowed to dry down without further irrigation, there was very little acidification of either the surface or subsurface layers. Planting of Phragmites accelerated soil drying and caused extensive cracking and acidification of the subsoil under simulated drought conditions. Under a wetting and drying regime, both Phragmites and a surface spreading grass Paspalum increased soil acidification, while a surface spreading herbaceous shrub Cotula had little effect on acidification. There was no evidence that live plants could ameliorate acid sulphate soils. However, application of dead plant matter to the surface of the soil was effective in reducing acidification, especially if submerged. Content Type Journal Article Pages 1-8 DOI 10.1007/s11104-011-0855-2 Authors Robert J. Reid, School of Earth and Environmental Sciences, DX650312, University of Adelaide, Adelaide, 5005 Australia Christopher S. Butcher, School of Earth and Environmental Sciences, DX650312, University of Adelaide, Adelaide, 5005 Australia Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description:    Effects of soil pH on damping-off of sugar beet by R. solani (AG2-2) and soil suppressiveness against the disease were studied by comparing disease incidences in pasteurized versus non-pasteurized, infested soils. Soil pH was correlated neither to disease incidence in five soils ranging from pH 4.5 to 7.2 nor to indigenous disease suppressiveness, the difference in disease incidences between non-treated soil and its pasteurized counterpart. When an alkaline soil was acidified with H 2 SO 4 , disease suppression markedly declined, increasing disease incidence in the non-pasteurized soil. Inversely, disease suppression was enhanced when an acidic soil was neutralized by adding Ca(OH) 2 . Soil amendment with dried peanut plant residue suppressed the disease in two pasteurized, near-neutral soils, lowering the incidence to the levels in the non-pasteurized soils, but was less effective in two pasteurized, acidic soils. In vitro mycelial growth of the pathogen and seedling growth was optimal at pH 4.5–5.5 and 6.0–6.5, respectively, and declined as the pH became higher or lower. (Conclusions) These results suggest that the seedlings were inhibited more than the pathogen at low pH, and that indigenous disease suppressiveness through the activity of antagonistic soil microorganisms operates effectively in near-alkaline soils, but is weakened or nullified in acidic soils. Content Type Journal Article Pages 1-14 DOI 10.1007/s11104-011-0843-6 Authors Kaori Watanabe, Department of Bio-productive Science, Faculty of Agriculture, Utsunomiya University, Utsunomiya, Tochigi, Japan Mariko Matsui, Department of Bio-productive Science, Faculty of Agriculture, Utsunomiya University, Utsunomiya, Tochigi, Japan Hitoshi Honjo, Department of Bio-productive Science, Faculty of Agriculture, Utsunomiya University, Utsunomiya, Tochigi, Japan J. Ole Becker, Department of Nematology, University of California at Riverside, Riverside, CA, USA Ryo Fukui, Department of Bio-productive Science, Faculty of Agriculture, Utsunomiya University, Utsunomiya, Tochigi, Japan Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description:    Salinity together with waterlogging or flooding, a condition that occurs frequently in the field, can cause severe damage to crops. Combined flooding and salinity decreases the growth and survival of plants more than either stress alone. We report here the first proteomic analysis to investigate the global effects of saline flooding on multiple metabolic pathways. Soybean seedlings at the emergence (VE) stage were treated with 100 mM NaCl and flooded with water or 100 mM sodium chloride solution for 2 days. Proteins were extracted from hypocotyl and root samples and analyzed by two-dimensional gel electrophoresis followed by MALDI-TOF, MALDI-TOF/TOF mass spectrometry or immunoblotting. A total of 43 reproducibly resolved, differentially expressed protein spots visualized by Coomassie brilliant blue staining were identified by MALDI-TOF MS. Identities of several proteins were also validated by MS/MS analysis or immunoblot analysis. Twenty-nine proteins were upregulated, eight proteins were downregulated and six spots were newly induced. The identified proteins include well-known salt and flooding induced proteins as well as novel proteins expressed by the salinity-flooding combined stress. The comparative analysis identified changes at the proteome level that are both specific and part of a common or shared response. The identification of such differentially expressed proteins provides new targets for future studies that will allow assessment of their physiological roles and significance in the response of glycophytes to a combination of flooding and salinity. Content Type Journal Article Pages 1-18 DOI 10.1007/s11104-011-0792-0 Authors Iftekhar Alam, Division of Applied Life Science (BK21 Program), IALS, PMBBRC, Gyeongsang National University, Jinju, 660-701 Korea Shamima Akhtar Sharmin, Division of Applied Life Science (BK21 Program), IALS, PMBBRC, Gyeongsang National University, Jinju, 660-701 Korea Kyung-Hee Kim, Division of Applied Life Science (BK21 Program), IALS, PMBBRC, Gyeongsang National University, Jinju, 660-701 Korea Yong-Goo Kim, Division of Applied Life Science (BK21 Program), IALS, PMBBRC, Gyeongsang National University, Jinju, 660-701 Korea Jeung Joo Lee, Department of Applied Biology, Gyeongsang National University, Jinju, 660-701 Korea Jeong Dong Bahk, Division of Applied Life Science (BK21 Program), IALS, PMBBRC, Gyeongsang National University, Jinju, 660-701 Korea Byung-Hyun Lee, Division of Applied Life Science (BK21 Program), IALS, PMBBRC, Gyeongsang National University, Jinju, 660-701 Korea Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description:    This study aims to investigate the colonization of poplar by the endophyte Pseudomonas putida W619 and its capacity to promote plant growth. Poplar cuttings were inoculated with P. putida W619 (wild-type or gfp -labelled). The colonization of both strains was investigated and morphological, physiological and biochemical parameters were analyzed to evaluate plant growth promotion. Inoculation with P. putida W619 (wild-type) resulted in remarkable growth promotion, decreased activities of antioxidative defence related enzymes, and reduced stomatal resistance, all indicative of improved plant health and growth in comparison with the non-inoculated cuttings. In contrast, inoculation with gfp -labelled P. putida W619 did not promote growth; it even had a negative effect on plant health and growth. Furthermore, compared to the wildtype strain, colonization by the gfp -labelled P. putida W619:: gfp 1 was much lower; it only colonized the rhizosphere and root cortex while the wild-type strain also colonized the root xylem vessels. Despite the strong plant growth promoting capacity of P. putida W619 (wild-type), after gfp labelling its growth promoting characteristics disappeared and its colonization capacity was strongly influenced; for these reasons gfp labelling should be applied with sufficient caution. Content Type Journal Article Pages 1-14 DOI 10.1007/s11104-011-0831-x Authors Nele Weyens, Environmental Biology, Hasselt University, Agoralaan Building D, B-3590 Diepenbeek, Belgium Jana Boulet, Environmental Biology, Hasselt University, Agoralaan Building D, B-3590 Diepenbeek, Belgium Dirk Adriaensen, Laboratory of Cell Biology & Histology, Department of Veterinary Sciences, Antwerp University, Groenenborgerlaan 171, 2020 Antwerp, Belgium Jean-Pierre Timmermans, Laboratory of Cell Biology & Histology, Department of Veterinary Sciences, Antwerp University, Groenenborgerlaan 171, 2020 Antwerp, Belgium Els Prinsen, Department of Biology, Groenenborgercampus, Antwerp University, Groenenborgerlaan 171, 2020 Antwerp, Belgium Sandra Van Oevelen, Department of Biology, Groenenborgercampus, Antwerp University, Groenenborgerlaan 171, 2020 Antwerp, Belgium Jan D’Haen, Institute for Materials Research, Hasselt University, Wetenschapspark 1, B-3590 Diepenbeek, Belgium Karen Smeets, Biodiversity, Phylogeny & Population Studies, Hasselt University, Agoralaan Building D, B-3590 Diepenbeek, Belgium Daniel van der Lelie, Research Triangle Institute (RTI), International 3040 Cornwallis Road, Research Triangle Park, NC 27709-2194, USA Safiyh Taghavi, Brookhaven National Laboratory (BNL), Biology Department, Building 463, Upton, NY 11973, USA Jaco Vangronsveld, Environmental Biology, Hasselt University, Agoralaan Building D, B-3590 Diepenbeek, Belgium Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description:    Plant growth promoting rhizobacteria (PGPR) confer disease resistance in many agricultural crops. In the case of Bacillus subtilis (UFLA285) isolated from the cotton producing state of Mato Grosso (Brazil), in addition to inducing foliar and root growth, disease resistance against damping-off caused by Rhizoctonia solani was observed. The aim of this cotton study was to identify gene transcriptional events altered with exposure to the PGPR strain UFLA285 in infected plants. Global gene transcription was profiled using a commercially-available cotton gene chip; cotton plants with and without UFLA285-seed treatment were infected with R. solani 9-days after planting and harvested on day14. Microarray data of stem tissue revealed 247 genes differentially regulated in infected plants, seed treated versus untreated with UFLA285. Transcripts encoding disease resistance proteins via jasmonate/ethylene signaling as well as osmotic regulation via proline synthesis genes were differentially expressed with UFLA285 induction. Consistent with transcriptional regulation, UFLA285 increased plant-proline accumulation and dry weight. This study has identified transcriptional changes in cotton, induced by the beneficial soil bacterium UFLA285 and associated with disease control. Content Type Journal Article Pages 1-11 DOI 10.1007/s11104-011-0852-5 Authors Flavio H. V. Medeiros, Departamento de Fitopatologia, Universidade Federal de Lavras, CP 3037, CEP 37200–000 Lavras, MG, Brazil Ricardo M. Souza, Departamento de Fitopatologia, Universidade Federal de Lavras, CP 3037, CEP 37200–000 Lavras, MG, Brazil Fernanda C. L. Medeiros, Departamento de Fitopatologia, Universidade Federal de Lavras, CP 3037, CEP 37200–000 Lavras, MG, Brazil Huiming Zhang, Departments of Chemistry and Biology, Texas Tech University, Lubbock, TX 79409, USA Terry Wheeler, TAES, Rt. 3, Box 219, Lubbock, TX 79403, USA Paxton Payton, United States Department of Agriculture, 3810 4th St, Lubbock, TX 79415, USA Henrique M. Ferro, Departamento de Fitopatologia, Universidade Federal de Lavras, CP 3037, CEP 37200–000 Lavras, MG, Brazil Paul W. Paré, Departments of Chemistry and Biology, Texas Tech University, Lubbock, TX 79409, USA Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description:    The objective of this study was to investigate how the management practices of prescribed fire and understorey vegetation removal affect water and nutrient relations of old, yet prematurely declining Eucalyptus gomphocephala . Long unburnt sites were established in Yalgorup National Park, Western Australia, adjacent to frequently burnt state forest sites. Trees were allocated to vegetation clearing, prescribed fire or no prescribed fire treatments. Prescribed fire was achieved in only one long unburnt national park site so that the results were pseudoreplicated but analysed accordingly. Soil chemistry, plant nutrient availability and tree foliar carbon and nitrogen isotope ratio and nutrient concentration were investigated. No effects of vegetation clearing were found. Prescribed fire sites were associated with sky exposure and bare ground whereas no prescribed fire sites were associated with shrub and litter cover and litter depth. Foliar carbon isotope ratios were significantly more negative in prescribed fire, relative to no prescribed fire, treatments on long unburnt sites. Soil exchangeable Zn and Mn and plant available (estimated by charged resin beads) Mg were higher on prescribed fire, relative to no prescribed fire, long unburnt sites. Seedling bioassays indicated elevated P and Cu availability on prescribed fire, relative to no prescribed fire, treatments. In overstorey E. gomphocephala , foliar N levels were elevated (but not to excessive levels), and there was a trend toward elevated foliar Mn, in prescribed fire relative to no prescribed fire treatments on long unburnt sites. In the context of our large-scale pseudoreplicated case study, prescribed fire provided a pulse of water and N, (with some indications towards provision of elevated Mn, Cu and Mg) availability to E. gomphocephala in decline on sites with a history of a long absence of fire that may in part underpin observations of elevated tree health on sites that have a history of relatively frequent fire. Content Type Journal Article Pages 1-12 DOI 10.1007/s11104-011-0862-3 Authors Dugald C. Close, School of Plant Science, The University of Tasmania, Private Bag 55, Hobart, Tasmania 7001, Australia Neil J. Davidson, School of Plant Science, The University of Tasmania, Private Bag 55, Hobart, Tasmania 7001, Australia Perry W. Swanborough, Bushfire CRC, Level 5, 340 Albert Street, East Melbourne, Victoria 3002, Australia Ross Corkrey, Tasmanian Institute of Agricultural Research, The University of Tasmania, Private Bag 54, Hobart, Tasmania 7001, Australia Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description:    Molecular techniques present a new opportunity to study roots and their interactions in soil. Extraction and quantification of species-specific DNA directly from soil allows direct identification of roots in mixed swards reducing the need for labour-intensive methods to recover and identify individual roots. DNA was extracted directly from up to 0.5 kg of soil and the presence of individual species quantified using species-specific probes with quantitative real-time PCR. A range of plant and soil factors influenced the DNA content measured in roots and it was necessary to account for these influences when converting DNA amount to root mass. The utility of the method for quantitative root studies was demonstrated in an experiment to investigate the effect of lime on root growth of acid-soil resistant and sensitive perennial grasses grown together in an aluminium-toxic soil. The root mass of an acid-soil resistant species was unaffected by lime application, whereas that of an acid-soil sensitive species was restricted by soil acidity. Molecular techniques present a promising tool for quantification of root mass directly in soil and have applications for field studies involving mixed species of plants. Content Type Journal Article Pages 1-15 DOI 10.1007/s11104-011-0846-3 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 Alan C. McKay, Plant and Soil Health, South Australian Research and Development Institute, Plant Research Centre, 2b Hartley Grove, Urrbrae, SA 5064, Australia Diana Hartley, CSIRO Ecosystem Sciences, GPO Box 1700, 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 Kathy Ophel-Keller, Plant and Soil Health, South Australian Research and Development Institute, Plant Research Centre, 2b Hartley Grove, Urrbrae, SA 5064, Australia Sue Wiebkin, Plant and Soil Health, South Australian Research and Development Institute, Plant Research Centre, 2b Hartley Grove, Urrbrae, SA 5064, Australia Herdina, Plant and Soil Health, South Australian Research and Development Institute, Plant Research Centre, 2b Hartley Grove, Urrbrae, SA 5064, Australia Ian T. Riley, Plant and Soil Health, South Australian Research and Development Institute, Plant Research Centre, 2b Hartley Grove, Urrbrae, SA 5064, 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:    A procedure for the construction of robust, upper bounds for the error in the finite element approximation of singularly perturbed reaction–diffusion problems was presented in Ainsworth and Babuška (SIAM J Numer Anal 36(2):331–353, 1999 ) which entailed the solution of an infinite dimensional local boundary value problem. It is not possible to solve this problem exactly and this fact was recognised in the above work where it was indicated that the limitation would be addressed in a subsequent article. We view the present work as fulfilling that promise and as completing the investigation begun in Ainsworth and Babuška (SIAM J Numer Anal 36(2):331–353, 1999 ) by removing the obligation to solve a local problem exactly. The resulting new estimator is indeed fully computable and the first to provide fully computable, robust upper bounds in the setting of singularly perturbed problems discretised by the finite element method. Content Type Journal Article Pages 1-25 DOI 10.1007/s00211-011-0384-1 Authors Mark Ainsworth, Department of Mathematics, Strathclyde University, 26 Richmond St., Glasgow, G1 1XH Scotland Tomáš Vejchodský, Institute of Mathematics, Academy of Sciences, Žitná 25, 115 67 Prague 1, Czech Republic Journal Numerische Mathematik Online ISSN 0945-3245 Print ISSN 0029-599X

Description:    Using short-term treatments, the aim of this study was to analyze the role of hydrogen peroxide in the regulation of AAO activity during Cd, Cu or IAA treatments in barley root tips. For analysis individual barley root segments were obtained by the gradual cutting of each root from the tip to the base 1, 2, 3 or 6 h after short-term treatments. Already a short 30 min exposure of barley roots to Cd induced significant root growth inhibition in a Cd concentration dependent manner, which was accompanied by a marked reduction of AAO activity. At Cu concentration which had no effect on the root growth a significant increase in AAO activity was observed. This increased AAO activity was detected only in ionically-bound CW fraction. In contrast, Cu at higher concentration and IAA inhibited both ionically-bound CW AAO isozymes. Prompt inhibition of AAO activity immediately after short-term treatment was observed only in the case of H 2 O 2 treatment suggesting that H 2 O 2 may act as an inhibitor of AAO. This was further supported by the observation that all Cd-, Cu- or IAA-induced root growth and AAO activity inhibition in barley roots was connected with an elevated production of H 2 O 2 . Content Type Journal Article Pages 1-9 DOI 10.1007/s11104-011-0869-9 Authors Veronika Zelinová, Institute of Botany, Slovak Academy of Sciences, Dúbravská cesta 9, SK-84523 Bratislava, Slovak Republic Ľubica Halušková, Institute of Botany, Slovak Academy of Sciences, Dúbravská cesta 9, SK-84523 Bratislava, Slovak Republic Igor Mistrík, Institute of Botany, Slovak Academy of Sciences, Dúbravská cesta 9, SK-84523 Bratislava, Slovak Republic Ladislav Tamás, Institute of Botany, Slovak Academy of Sciences, Dúbravská cesta 9, SK-84523 Bratislava, Slovak Republic Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description:    It is known that the number of limiting nutrients may affect the species richness of plant communities, but it is unclear whether the type of nutrient limitation is also important. I place the results from a study in Patagonia (elsewhere in this issue) in the context of the number and types of nutrients that are limiting. I present four mechanisms through which N or P limitation may potentially influence species richness. These mechanisms are related to: (i) the number of forms in which P or N are present in soil and the plant traits needed to acquire them, (ii) the mechanisms and traits that control species competition and coexistence under N or P limitation, (iii) the regional species pools of plants capable of growing under N- and P-limited conditions, and (iv) the interaction between the type of nutrient limitation and community productivity. It appears likely that P limitation can favour a higher species richness than N limitation, in at least in a variety of low productive plant communities, but evidence to support this conclusion is so far lacking. The four mechanisms proposed here offer a framework for exploring whether the type of nutrient limitation per se, or an interaction with productivity, is a potential driver for variation in species diversity. Content Type Journal Article Pages 1-9 DOI 10.1007/s11104-011-0796-9 Authors Harry Olde Venterink, Institute of Integrative Biology, ETH Zurich, Universitätsstrasse 16, 8092 Zurich, Switzerland Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description:    Ammonia (NH 3 ) fluxes between beech leaves ( Fagus sylvatica ) and the atmosphere were investigated in a 90-year-old forest canopy and related to leaf nitrogen (N) pools and glutamine synthetase (GS) activities. The stomatal ammonia compensation point, χ NH 3 , was measured by both a twig cuvette and bioassay techniques involving measurements of pH and ammonium (NH 4 + ) concentration in the leaf apoplastic solution. The χ NH 3 determined on the basis of the gas exchange measurements followed a seasonal variation with early-season peaks during leaf expansion (9.6 nmol NH 3 mol −1 air) and late-season peaks during leaf senescence (7.3 nmol NH 3 mol −1 air). In the mid-season, the χ NH 3 of mature green leaves was much lower (around 3 nmol NH 3 mol −1 air) and dropped below the NH 3 concentration in the ambient atmosphere. For comparison, χ NH 3 obtained by the apoplastic bioassay were 7.0, 3.7 and 6.4 nmol NH 3 mol −1 air in early-, mid-, and late -season, thus agreeing reasonably well with χ NH 3 values derived from the gas exchange measurements. Potential NH 3 emission fluxes during early and late season were 1.31 and 0.51 nmol m −2 leaf surface area s −1 , respectively, while leaves were a sink for NH 3 during mid-season. During leaf establishment and senescence, both apoplastic and bulk tissue NH 4 + concentrations were relatively high coinciding with low activities of glutamine synthetase, which is a key enzyme in leaf N metabolism. In conclusion, the exchange of NH 3 between beech leaves and the atmosphere followed a seasonal variation with NH 3 emission peaks being related to N mobilization during early leaf establishment and remobilization during late leaf senescence. Content Type Journal Article Pages 1-16 DOI 10.1007/s11104-010-0693-7 Authors Liang Wang, Plant and Soil Science Section, Faculty of Life Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Copenhagen Denmark Yingchun Xu, Plant and Soil Science Section, Faculty of Life Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Copenhagen Denmark Jan Kofod Schjoerring, Plant and Soil Science Section, Faculty of Life Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Copenhagen Denmark Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description:    Boron (B) deficiency depresses wheat, barley and triticale yield through male sterility. On the basis of field responses to B fertilization, maize ( Zea mays L.) is affected by B deficiency in five continents. In a series of sand culture trials with maize subject to B0 (nil added B) and B20 (20 μM added B) treatments, we described how B deficiency depressed maize grain yield while showing an imperceptible effect on vegetative dry weight. With manual application of pollen to the silk of each plant, B0 plants produced 0.4 grain ear −1 compared with 410 grains ear −1 in B20 plants. Symptoms of B deficiency was observed only in B0 plants, which exhibited symptoms of narrow white to transparent lengthwise streaks on leaves, multiple but small and abnormal ears with very short silk, small tassels with some branches emerging dead, and small, shrivelled anthers devoid of pollen. Tassels, silk and pollen of B0 plants contained only 3–4 mg B kg −1 DW compared with twice or more B in these reproductive tissues in B20 plants. A cross-fertilization experiment showed that, although the tassels and pollen were more affected, the silk was more sensitive to B deficiency. Pollen from B20 plants applied to B0 silk produced almost no grains, while pollen from B0 on B20 silk increased the number of grains to 37% of the 452 grains plant −1 produced from B20 pollen on B20 silk. Therefore, the silk of the first ear may be targeted for precise diagnosis of B status at maize reproduction, for timely correction by foliar B application, and even for B-efficient genotype selection. Content Type Journal Article Pages 1-14 DOI 10.1007/s11104-010-0685-7 Authors Sittichai Lordkaew, Multiple Cropping Center, Faculty of Agriculture, Chiang Mai University, Chiang Mai, 50200 Thailand Bernard Dell, Sustainable Ecosystem Research Institute, Murdoch University, Perth, 6150 Australia Sansanee Jamjod, Department of Plant Science and Natural Resources, Faculty of Agriculture, Chiang Mai University, Chiang Mai, 50200 Thailand Benjavan Rerkasem, 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:    Oxidation by soil bacteria is the only biological sink for atmospheric methane (CH 4 ). There are substantial uncertainties regarding the global size of this sink, in part because the ecological controls of the involved processes are not well understood to date. We have investigated effects of severe summer drought and of nitrogen inputs (ammonium nitrate or cattle urine) on soil CH 4 fluxes in a field experiment. Soil moisture was the most important factor regulating the temporal dynamics of CH 4 fluxes. Simulated drought episodes altered the soil’s water balance throughout the year, increasing CH 4 oxidation by 50% on an annual basis. N fertilizers exerted only small and transient effects at the ecosystem level. Laboratory incubations suggested that effects differed between soil layers, with larger effects of drought and N application in the top soil than in deeper layers. With soil moisture being the primary controlling factor of methanotrophy, a detailed understanding of the ecosystem’s water balance is required to predict CH 4 budgets under future climatic conditions. Content Type Journal Article Pages 1-11 DOI 10.1007/s11104-010-0690-x Authors Adrian A. Hartmann, Institute of Plant, Animal and Agroecosystem Sciences, ETH Zurich, Universitätsstr. 2, 8092 Zurich, Switzerland Nina Buchmann, Institute of Plant, Animal and Agroecosystem Sciences, ETH Zurich, Universitätsstr. 2, 8092 Zurich, Switzerland Pascal A. Niklaus, Institute of Plant, Animal and Agroecosystem Sciences, ETH Zurich, Universitätsstr. 2, 8092 Zurich, Switzerland Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description:    Phosphorus (P) loss from land can impair surface water quality. Losses can occur from soil and plant components. While it is known that P losses increase with soil P concentration, it is not known how losses from pasture plants vary with soil P concentration or between different forages. We examined total P and filterable reactive P (FRP) in water extracts of plant shoots, used as a measure of potential P loss to surface runoff, in different forage species relative to soil P concentration in field trials and a glasshouse experiment. The mean total P concentration of 16 forage species in grazed field plots was greater ( P  〈 0.01; LSD 05  = 117 mg kg −1 ) in legumes (3,480 mg kg −1 ) than for grasses (3,210 mg kg −1 ). Total plant P concentrations of grasses and legumes increased with soil Mehlich-3 P concentrations in both glasshouse and field trials with concentrations close to 6,000 mg kg −1 in arrowleaf clover at 680 mg kg −1 Mehlich-3 soil P. FRP in water extracts of plant shoots increased relative to plant total P as soil Mehlich-3 P increased, with the greatest concentrations shown by crimson clover and arrowleaf clover. Analysis of water extracts of ryegrass and clover herbage from a field trial showed that while FRP was increasing, phytase-available-P decreased significantly from about 70% of filterable unreactive P at the lowest Mehlich-3 P concentrations, to close to zero at 200 mg kg −1 Mehlich-3 P. The wide variation, and enrichment of FRP in water extracts and total P with increasing Mehlich-3 P among species, indicates that cultivar and site selection and sward management provide a potential option to mitigate P loss to surface waters. Content Type Journal Article Pages 1-13 DOI 10.1007/s11104-010-0687-5 Authors Richard W. McDowell, AgResearch, Invermay Agricultural Centre, Private Bag 50034, Mosgiel, 9053 New Zealand Andrew N. Sharpley, Department of Soil, Crop and Environmental Science, University of Arkansas, Fayetteville, AR USA James R. Crush, AgResearch, Ruakura Research Centre, Private Bag 3123, Hamilton, 3240 New Zealand Tara Simmons, Department of Soil, Crop and Environmental Science, University of Arkansas, Fayetteville, AR USA Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description:    Hydraulic redistribution is the process where soil water is translocated by plant roots from wet to dry areas as it is drawn through xylem pathways by a water potential gradient. Hydraulic redistribution places soil water resources where they would otherwise not be, which results in a range of ecological and hydrological consequences. Although deep-rooted plants can transfer water up from depth into shallow soil layers, any localised ‘irrigation’ of neighbouring plants tends to be obscured by recovery of the very same water by the donor plants during daytime transpiration. A new intercropping system was recently trialled which eliminates transpiration by the donor plant through complete shoot removal in order to maximise hydraulic redistribution. In the absence of any transpiring shoots, the donor plants are left to wick water up from depth 24 hours a day via their root systems, to the benefit of neighbouring shallow-rooted crops. This system allows deeper-rooted ‘nurse plants’ to capture water that is out of reach of crops in a ‘water safety-net’ role, which may be of considerable benefit in water-scarce environments. Content Type Journal Article Pages 1-5 DOI 10.1007/s11104-010-0638-1 Authors Stephen S. O. Burgess, School of Plant Biology, University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description:    Humidity is an important determinant of the mycotoxin production (DON, ZEA) by Fusarium species in the grain ears. From a landscape perspective humidity is not evenly distributed across fields. The topographically-controlled redistribution of water within a single field rather leads to spatially heterogeneous soil water content and air humidity. Therefore we hypothesized that the spatial distribution of mycotoxins is related to these topographically-controlled factors. To test this hypothesis we studied the mycotoxin concentrations at contrasting topographic relief positions, i.e. hilltops and depressions characterized by soils of different soil moisture regimes, on ten winter wheat fields in 2006 and 2007. Maize was the preceding crop and minimum tillage was practiced in the fields. The different topographic positions were associated with moderate differences in DON and ZEA concentrations in 2006, but with significant differences in 2007, with six times higher median ZEA and two times higher median DON detected at depression sites compared to the hilltops. The depression sites correspond to a higher topographic wetness index as well as redoximorphic properties in soil profiles, which empirically supports our hypothesis at least for years showing wetter conditions in sensitive time windows for Fusarium infections. Content Type Journal Article Pages 1-12 DOI 10.1007/s11104-010-0695-5 Authors Marina Elsa Herta Müller, Leibniz-Centre for Agricultural Landscape Research, Institute of Landscape Matter Dynamics, Eberswalder Str. 84, 15374 Müncheberg, Germany Sylvia Koszinski, Leibniz-Centre for Agricultural Landscape Research, Institute of Soil Landscape Research, Eberswalder Str. 84, 15374 Müncheberg, Germany Alexander Brenning, Department of Geography and Environmental Management, University of Waterloo, 200 University Ave. W, Waterloo, ON N2L 3G1, Canada Gernot Verch, Leibniz-Centre for Agricultural Landscape Research, Research Station Dedelow, OT Dedelow, Steinfurter Str. 14, 17291 Prenzlau, Germany Ulrike Korn, Leibniz-Centre for Agricultural Landscape Research, Institute of Landscape Matter Dynamics, Eberswalder Str. 84, 15374 Müncheberg, Germany Michael Sommer, Leibniz-Centre for Agricultural Landscape Research, Institute of Soil Landscape Research, Eberswalder Str. 84, 15374 Müncheberg, Germany Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description:    Arbuscular mycorrhizal fungi (AMF) are crucial for ecosystem functioning, and thus have potential use for sustainable agriculture. In this study, we investigated the impact of organic and mineral fertilizers on the AMF community composition and content of Glomalin-related soil protein (GRSP) in a field experimental station which was established in 1979, in the Loess Plateau of China. Roots and soils were sampled three times during the growing period of winter wheat in 2008. The treatments including: N (inorganic N), NP (inorganic N and P), SNP (straw, inorganic N and P), M (farmyard manure), MNP (farmyard manure, inorganic N and P), and CK (no fertilization). AMF communities of root and soil samples were analyzed using PCR-DGGE, cloning and sequencing techniques; and GRSP content was determined by Bradford assay. Our results indicated that spore density, GRSP, and AMF community varied significantly in soils of long-term fertilization plots at three different wheat growing stages. The effects of wheat growing period on AMF community in roots were much more evident than fertilization regimes. However, the diversity of AMF was low in our study field. Up to five AMF phylotypes appeared in each sample, with the overwhelming dominance of a Glomus -like phylotype affiliated to G. mosseae . GRSP content was correlated positively with organic carbon, total phosphorus, available phosphorus, soil pH, and spore densities, but correlated negatively with soil C/N ( P  〈 0.05). The results of our study highlight that the richness of AMF in Loess Plateau agricultural region is low, and long-term fertilization, especially amendments with manure and straw, has beneficial effects on accumulation of soil organic carbon, spore density, GRSP content, and AMF diversity. Host phenology, edaphic factors (influenced by long-term fertilization), and habitats interacted to affect the AMF community and agoecosystem functioning. Additionally, soil moisture and pH make a greater contribution than other determined soil parameters to the AMF community dynamics in such a special semi-arid agroecosystem where crops rely greatly on rainfall. Content Type Journal Article Pages 1-15 DOI 10.1007/s11104-010-0688-4 Authors Fasi Wu, School of Life Sciences, Key Lab of Arid and Grassland Ecology of Ministry of Education, Lanzhou University, Lanzhou, 730000 People’s Repulic of China Maoxing Dong, School of Life Sciences, Key Lab of Arid and Grassland Ecology of Ministry of Education, Lanzhou University, Lanzhou, 730000 People’s Repulic of China Yongjun Liu, School of Life Sciences, Key Lab of Arid and Grassland Ecology of Ministry of Education, Lanzhou University, Lanzhou, 730000 People’s Repulic of China Xiaojun Ma, School of Life Sciences, Key Lab of Arid and Grassland Ecology of Ministry of Education, Lanzhou University, Lanzhou, 730000 People’s Repulic of China Lizhe An, School of Life Sciences, Key Lab of Arid and Grassland Ecology of Ministry of Education, Lanzhou University, Lanzhou, 730000 People’s Repulic of China J. Peter W. Young, Department of Biology, University of York, PO Box 373, York, YO10 5YW UK Huyuan Feng, School of Life Sciences, Key Lab of Arid and Grassland Ecology of Ministry of Education, Lanzhou University, Lanzhou, 730000 People’s Repulic of China Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description:    Rhizotoxic effects of many trace metals are known, but there is little information on recovery after exposure. Roots of 3-d-old cowpea ( Vigna unguiculata (L.) Walp. cv. Caloona) seedlings were grown for 4 or 12 h in solutions of 960 μM Ca and 5 μM B at two concentrations (which reduce growth by 50 or 85%) of nine trace metals that rupture the outer layers of roots. Measured concentrations were 34 or 160 μM Al, 0.6 or 1.6 μM Cu, 2.2 or 8.5 μM  Ga, 2.3 or 12 μM Gd, 0.8 or 1.9 μM Hg, 1.0 or 26 μM In, 2.4 or 7.3 μM La, 1.8 or 3.8 μM Ru, and 1.3 or 8.6 μM Sc. Roots were rinsed, transferred to solutions free of trace metals, and regrowth monitored for up to 48 h. Recovery from exposure to Hg occurred within 4 h, but regrowth was delayed for ≥ 12 h with Al, Ga, or Ru. There was poor regrowth after 4 or 12 h exposure to Cu, Gd, In, La, or Sc. Roots recovered after being grown for 12 to 48 h in 170 μM Al, 5.1 μM  Ga, 2.0 μM Hg, or 1.4 μM Ru, but the extent of recovery was reduced with longer exposure time. Microscopy showed marked differences in symptoms on roots recovering from exposure to the various trace metals. Differences in (i) concentrations that are toxic, (ii) ability of roots to recover, (iii) time for recovery to occur, and (iv) symptoms that develop, suggest that each trace metal has a unique combination of rhizotoxic effects. Content Type Journal Article Pages 1-14 DOI 10.1007/s11104-010-0655-0 Authors F. P. C. Blamey, School of Land, Crop and Food Sciences, The University of Queensland, St. Lucia, Queensland Australia 4072 P. M. Kopittke, School of Land, Crop and Food Sciences, The University of Queensland, St. Lucia, Queensland Australia 4072 J. B. Wehr, School of Land, Crop and Food Sciences, The University of Queensland, St. Lucia, Queensland Australia 4072 N. W. Menzies, School of Land, Crop and Food Sciences, The University of Queensland, St. Lucia, Queensland Australia 4072 Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description:    We identified the role of various soil parameters and root density as drivers of soil respiration (R s ) in an apple orchard, measured during different periods of the year and at a range of distances from trees, in plots with a different history of nutrient supply. R s was measured in April, May, August and December and studied in relation to soil temperature and moisture, total soil C and N, as well as to fine root density and medium-, and large-sized root density and root N concentration. The study also aimed to partition R s by applying the root regression technique. R s ranged from 0.06 in December to 1.49 g CO 2 m −2  h −1 in August. Average soil temperature alone explained up to 71% of the annual variability of R s , while soil water content was negatively correlated to R s . Fertilization, soil C and N concentration and root N had negligible effects on R s . Fine root density, but not medium- and large-sized root density, contributed to explaining part of the yearly variability of R s and proved to be a good predictor in December, when the statistical significance of the regression made it possible to estimate the autotrophic component of R s as being about 35% of total soil respiration. Content Type Journal Article Pages 1-12 DOI 10.1007/s11104-010-0684-8 Authors Christian Ceccon, Department of Fruit Tree and Woody Plant Sciences, Bologna University, Viale Fanin 46, 40127 Bologna, Italy Pietro Panzacchi, Department of Fruit Tree and Woody Plant Sciences, Bologna University, Viale Fanin 46, 40127 Bologna, Italy Francesca Scandellari, Department of Fruit Tree and Woody Plant Sciences, Bologna University, Viale Fanin 46, 40127 Bologna, Italy Luca Prandi, Department of Fruit Tree and Woody Plant Sciences, Bologna University, Viale Fanin 46, 40127 Bologna, Italy Maurizio Ventura, Department of Fruit Tree and Woody Plant Sciences, Bologna University, Viale Fanin 46, 40127 Bologna, Italy Barbara Russo, Faculty of Computer Science, Free University of Bolzano/Bozen, Piazza Università 1, 39100 Bolzano, Italy Peter Millard, The Macaulay Land Use Research Institute, Aberdeen, AB15 8QJ UK Massimo Tagliavini, Faculty of Science and Technology, Free University of Bolzano/Bozen, Piazza Università 5, 39100 Bolzano, Italy Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description:    Mutations affecting the development of root symbiosis between legume plants ( Fabaceae ) and nodule bacteria (rhizobia) are often associated with pleiotropy. This might either primarily be caused by the mutation or develops as a physiological consequence of a changed nodule structure, number and activity. Three pleiotropic traits were revealed in the pea ( Pisum sativum L.) mutant RisfixC which is of supernodulation/nitrate-tolerant symbiosis (Nts) type. They comprise shortened internodes, reduced shoot dry mass accumulation and increased nitrogen content in the root tissues when compared to the wild type. The changes were expressed in the same degree in asymbiotic and nodulated plants when the effect of symbiotic nitrogen on plant growth was abolished with a saturating nitrate level. Consequently, the pleiotropic traits are inherently associated with the mutation. In RisfixC, the pleiotropy coincided with the presumed absence of the systemic feedback factor regulating nodule number. However, no differences were detected in the comparison of nonnodulating mutant Risnod27 ( sym8 ) with the wild type and of inoculated with noninoculated wild-type plants although these pairs also differ in the presence of the systemic factor. Therefore, the pathway leading from the RisfixC mutant product to pleiotropic changes appears to be independent of systemic nodule number regulation. Implications for the genetic improvement of growth and yield parameters of supernodulating breeding lines are discussed. Content Type Journal Article Pages 1-10 DOI 10.1007/s11104-010-0682-x Authors Karel Novák, Institute of Microbiology AS CR, Vídeňská 1083, 142 20 Prague 4, Czech Republic Ludmila Lisá, Institute of Microbiology AS CR, Vídeňská 1083, 142 20 Prague 4, Czech Republic Vladimír Škrdleta, Institute of Microbiology AS CR, Vídeňská 1083, 142 20 Prague 4, Czech Republic Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description:    A discrepancy between plant demand and soil supply of nitrogen (N) has been observed in early successional stages of riparian vegetation in interior Alaska. We hypothesized that a hydrologically mediated N supply serves as a mechanism to balance this apparent deficiency of plant N supply. To test this hypothesis, we conducted a tracer experiment and measured the activity of nitrate reductase (NRA) over the summer on the early successional floodplain of the Tanana River in interior Alaska. Isotopic data showed that river-/groundwater was an important source of plant water and that hyporheic N could be absorbed by early successional species. Plant NRA generally increased as the growing season progressed, and NO 3 − -N availability increased. Both Salix interior Rowlee and Populus balsamifera L. used NO 3 − -N, and the timing of plant NRA relative to river discharge chemistry and soil NO 3 − -N concentrations, strongly suggest that plant uptake of NO 3 − -N is coupled to fluvial dynamics. Moreover, this physiological function helps explain the apparent discrepancy between N mineralization and productivity in these riparian ecosystems, and demonstrates that plant N availability in these riparian stands is under significant hydrological control. Content Type Journal Article Pages 1-11 DOI 10.1007/s11104-010-0676-8 Authors Lina Koyama, Graduate School of Informatics, Kyoto University, Kyoto, 606-8501 Japan Knut Kielland, Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK 99775, USA Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description:    Phytolith Occluded Carbon (PhytOC) has recently been demonstrated to be an important long-term terrestrial carbon fraction. The aim of this study was to examine the rates of silica accumulation and carbon bio-sequestered within the silica phytoliths of the leaf and stem material of wheat (Triticum sp.) cultivars. The phytolith content of 53 wheat cultivars sourced from 25 countries around the world and grown on a single trial site was first isolated and the PhytOC content then determined. The data shows that the phytolith occluded carbon content of the wheat cultivars ranged from 0.06% to 0.60% of dry leaf and stem biomass: a range of 1,000%. The data also demonstrates that it is the efficiency by which carbon is encapsulated within silica rather than the quantity of silica accumulated by the plant that is the most important factor in determining the relative PhytOC yields. The potential phytolith carbon bio-sequestration rates in the leaf and stem components of these wheat cultivars ranged up to 0.246 t-e-CO 2 ha −1 y −1 . These phytolith carbon bio-sequestration rates indicate a substantial potential (~50 million t-e-CO 2 y −1 ) exists for increasing the rate of secure carbon bio-sequestration in wheat crops using existing cultivars. Content Type Journal Article Pages 1-7 DOI 10.1007/s11104-010-0680-z Authors Jeffrey F. Parr, Southern Cross GeoScience, Southern Cross University, Lismore, NSW 2480, Australia Leigh A. Sullivan, Southern Cross GeoScience, Southern Cross University, Lismore, NSW 2480, Australia Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description:    We present a hierarchical a posteriori error analysis for the minimum value of the energy functional in symmetric obstacle problems. The main result is that the error in the energy minimum is, up to oscillation terms, equivalent to an appropriate hierarchical estimator. The proof does not invoke any saturation assumption. We even show that small oscillation implies a related saturation assumption. In addition, we prove efficiency and reliability of an a posteriori estimate of the discretization error and thereby cast some light on the theoretical understanding of previous hierarchical estimators. Finally, we illustrate our theoretical results by numerical computations. Content Type Journal Article Pages 1-25 DOI 10.1007/s00211-011-0364-5 Authors Qingsong Zou, Freie Universität Berlin, Berlin, Germany Andreas Veeser, Freie Universität Berlin, Berlin, Germany Ralf Kornhuber, Freie Universität Berlin, Berlin, Germany Carsten Gräser, Freie Universität Berlin, Berlin, Germany Journal Numerische Mathematik Online ISSN 0945-3245 Print ISSN 0029-599X

Description:    In this article, we give a new rigorous condition number estimate of the finite element tearing and interconnecting (FETI) method and a variant thereof, all-floating FETI. We consider a scalar elliptic equation in a two- or three-dimensional domain with a highly heterogeneous (multiscale) diffusion coefficient. This coefficient is allowed to have large jumps not only across but also along subdomain interfaces and in the interior of the subdomains. In other words, the subdomain partitioning does not need to resolve any jumps in the coefficient. Under suitable assumptions, we derive bounds for the condition numbers of one-level and all-floating FETI that are robust with respect to strong variations in the contrast in the coefficient, and that are explicit in some geometric parameters associated with the coefficient variation. In particular, robustness holds for face, edge, and vertex islands in high-contrast media. As a central tool we prove and use new weighted Poincaré and discrete Sobolev type inequalities that are explicit in the weight. Our theoretical findings are confirmed in a series of numerical experiments. Content Type Journal Article Pages 1-45 DOI 10.1007/s00211-011-0359-2 Authors Clemens Pechstein, Institute of Computational Mathematics, Johannes Kepler University, Altenberger Str. 69, 4040 Linz, Austria Robert Scheichl, Department of Mathematical Sciences, University of Bath, Bath, BA2 7AY UK Journal Numerische Mathematik Online ISSN 0945-3245 Print ISSN 0029-599X

Description:    We consider the Fourier analysis of multigrid methods (of Galerkin type) for symmetric positive definite and semi-positive definite linear systems arising from the discretization of scalar partial differential equations (PDEs). We relate the so-called smoothing factor to the actual two-grid convergence rate and also to the convergence rate of the V-cycle multigrid. We derive a two-sided bound that defines an interval containing both the two-grid and V-cycle convergence rate. This interval is narrow and away from 1 when both the smoothing factor and an additional parameter are small enough. Besides the smoothing factor, the convergence mainly depends on the angle between the range of the prolongation and the eigenvectors of the system matrix associated with small eigenvalues. Nice V-cycle convergence is guaranteed if the tangent of this angle has an upper bound proportional to the eigenvalue, whereas nice two-grid convergence requires a bound proportional to the square root of the eigenvalue. We also discuss the well-known rule which relates the order of the prolongation to that of the differential operator associated to the problem. We first define a frequency based order which in most cases amounts to the so-called high frequency order as defined in Hemker (J Comput Appl Math 32:423–429, 1990 ). We give a firmer basis to the related order rule by showing that, together with the requirement of having the smoothing factor away from one, it provides necessary and sufficient conditions for having the two-grid convergence rate away from 1. A stronger condition is further shown to be sufficient for optimal convergence with the V-cycle. The presented results apply to rigorous Fourier analysis for regular discrete PDEs, and also to local Fourier analysis via the discussion of semi-positive systems as may arise from the discretization of PDEs with periodic boundary conditions. Content Type Journal Article Pages 1-27 DOI 10.1007/s00211-011-0362-7 Authors Artem Napov, Service de Métrologie Nucléaire, Université Libre de Bruxelles (C.P. 165/84), 50, Av. F.D. Roosevelt, 1050 Brussels, Belgium Yvan Notay, Service de Métrologie Nucléaire, Université Libre de Bruxelles (C.P. 165/84), 50, Av. F.D. Roosevelt, 1050 Brussels, Belgium Journal Numerische Mathematik Online ISSN 0945-3245 Print ISSN 0029-599X

Description:    Dynamic root-development models are indispensable for biomechanical and biomass allocation studies, and also play an important role in understanding slope stability. There are few root-development models in the literature, and there is a specific lack of dynamic models. Therefore, the aim of this study is to develop a 3D growth-development model for coarse roots, which is species independent, as long as annual rings are formed. In order to implement this model, the objectives are (I) to interpolate annual growth layers, and (II) to evaluate the interpolations and annual volume computations. The model developed is a combination of 3D laser scans and 2D tree-ring data. A FARO laser ScanArm is used to acquire the coarse-root structure. A MATLAB program then integrates the ring-width measurements into the 3D model. A weighted interpolation algorithm is used to compute cross sections at any point within the model to obtain growth layers. The algorithm considers both the root structure and the ring-width data. The model reconstructed ring profiles with a mean absolute error for mean ring chronologies of 〈9% and for single radii of 〈20%. The interpolation accuracy was dependent on the number of input sections and root curvature. Total volume computations deviated by 3.5–6.6% from the reference model. A new robust root-modelling tool was developed which allows for annual volume computations and sophisticated root-development analyses. Content Type Journal Article Pages 1-18 DOI 10.1007/s11104-011-0797-8 Authors Bettina Wagner, Swiss Federal Research Institute WSL, Zürcherstrasse 111, 8903 Birmensdorf, Switzerland Silvia Santini, Institute for Pervasive Computing, ETH Zurich, 8092 Zurich, Switzerland Hilmar Ingensand, Institute of Geodesy and Photogrammetry, ETH Zurich, 8093 Zurich, Switzerland Holger Gärtner, Swiss Federal Research Institute WSL, Zürcherstrasse 111, 8903 Birmensdorf, Switzerland Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description:    Positive effects of sugar beet (SB) application on soil properties and performance of several woody shrub legumes have been described under heavy metal stress and in diverse degraded environments, especially when combined with arbuscular mycorrhiza (AM). However, information on the combined effect of SB amendments and AM symbiosis in horticultural crop plants under drought stress is scarce. Thus, the main objective of this work was to determine if the combination of treated SB waste and AM fungi results in improved drought tolerance of an horticultural food crop such as lettuce and whether or not the effects observed are linked to enhanced antioxidant activities and regulation of two stress-related genes. Lettuce plants inoculated or not with Glomus intraradices and grown on soil amended or not with a treated SB waste were cultivated under well-watered conditions or subjected to drought stress. Plant growth, expression of two drought responsive genes encoding for Δ 1 -pyrroline-5-carboxylate synthetase and 9-cis -epoxycarotenoid dioxygenase, oxidative damage to lipids and the activity of four antioxidant enzymes were measured. Results showed that the application of treated SB waste resulted negative for the development of AM and nonAM plants (both under well-watered and under drought stress conditions). This effect can not be ascribed to the impairment of specific plant antioxidant defenses. In contrast, a lack of induction of a gene from the ABA biosynthetic pathway was observed in SB-treated plants, which could have contributed to the low performance of these plants. The positive effects of combined application of treated SB waste as amendment and AM fungi have not been shown for a horticultural food crop such as Lactuca sativa . Thus, before starting a program aimed at the utilization of different amendments based on transformed wastes, basic studies on functional and physiological compatibility between the plant and the amendment are necessary. Content Type Journal Article Pages 1-14 DOI 10.1007/s11104-011-0805-z Authors Juan Manuel Ruíz-Lozano, Departamento de Microbiología del Suelo y Sistemas Simbióticos, Estación Experimental del Zaidín (CSIC), Profesor Albareda nº 1, 18008 Granada, Spain María del Carmen Perálvarez, Departamento de Microbiología del Suelo y Sistemas Simbióticos, Estación Experimental del Zaidín (CSIC), Profesor Albareda nº 1, 18008 Granada, Spain Ricardo Aroca, Departamento de Microbiología del Suelo y Sistemas Simbióticos, Estación Experimental del Zaidín (CSIC), Profesor Albareda nº 1, 18008 Granada, Spain Rosario Azcón, Departamento de Microbiología del Suelo y Sistemas Simbióticos, Estación Experimental del Zaidín (CSIC), Profesor Albareda nº 1, 18008 Granada, Spain Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description:    Urbanization has been rapid across the world but the responses of phosphorus (P) cycling to urbanization have not been well-investigated. This study was to understand the influences of rapid urbanization on forest P cycling in a developing country. Soil P fractions and P resportion were determined for nine slash pine ( Pinus elliottii Engelm.) forests along a 30-km long urban-suburban-rural gradient in Nanchang City, southern China. The total P stocks in the surface soils in urban and suburban forests were 317% and 182% higher, respectively, than levels found in rural forests. The concentrations of soil available P, labile P, slow P, occluded P and total extractable P were also much higher in urban and suburban forests than in rural forests ( P  〈 0.05). Soil weathered P concentrations were highest in urban forests. Annual mean foliar P concentrations were enhanced in urban and suburban forests compared to rural forests. The P resorption efficiency (PRE) was higher in rural forests than in suburban and urban forests, while the P resorption proficiency (PRP) was lower in rural forests than in suburban and urban forests. Urbanization associated with high extraneous P inputs has altered soil P status and plant P uptake. Foliar P concentration, PRE and PRP were largely dependent on soil P availability in our study forests. Content Type Journal Article Pages 1-10 DOI 10.1007/s11104-011-0799-6 Authors Xiao-Fei Hu, College of Life Sciences, Nanchang University, Nanchang, 330031 China Fu-Sheng Chen, College of Life Sciences, Nanchang University, Nanchang, 330031 China Gregory Nagle, Department of Natural Resources, Cornell University, Ithaca, NY 14853, USA Yun-Ting Fang, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650 China Ming-Quan Yu, College of Life Sciences, Jiangxi Science & Technology Normal University, Nanchang, 330038 China Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description:    Loss of functional diversity has been demonstrated to have a variety of impacts on ecosystem functioning. However, most studies have been implemented in artificially assembled communities by removing the original vegetation and seeding with desired species or functional group compositions. Such approaches could significantly disturb belowground biomass, especially roots, making it difficult to examine belowground responses to diversity manipulations. To circumvent this issue, plant diversity gradients were established by in situ removal of aboveground biomass of different plant functional groups (PFGs) in a typical steppe, and belowground processes related to roots and soil were examined. Root nutrient pools exhibited contrasting patterns, with the phosphorus (P) pool decreasing linearly upon increased PFG removal while the nitrogen (N) pool had a hump-shaped response. Soil NO 3− increased while net N mineralization decreased with PFG removal. In contrast, soil P showed little response to PFG removal. Furthermore, both the identity and number of PFG removed had a significant influence on root and soil properties. The results of this study showed that loss of a combination of PFGs was important in natural grassland, and an approach with minimal influence on belowground processes is promising in studying diversity loss effects in natural ecosystems. Content Type Journal Article Pages 1-12 DOI 10.1007/s11104-011-0803-1 Authors Deliang Kong, Key Laboratory for Urban Habitat Environmental Science and Technology, Peking University Shenzhen Graduate School, Shenzhen, 518055 China Huifang Wu, Department of Horticulture, Institute of Agricultural Sciences, Nanyang, 473000 China Hui Zeng, Key Laboratory for Urban Habitat Environmental Science and Technology, Peking University Shenzhen Graduate School, Shenzhen, 518055 China Xiaotao Lü, Key Laboratory of Vegetation and Environmental Change Institute of Botany, Chinese Academy of Sciences, No.20 Nanxincun, Xiangshan, 100093 Beijing, China Matthew Simmons, Key Laboratory of Vegetation and Environmental Change Institute of Botany, Chinese Academy of Sciences, No.20 Nanxincun, Xiangshan, 100093 Beijing, China Meng Wang, Key Laboratory of Vegetation and Environmental Change Institute of Botany, Chinese Academy of Sciences, No.20 Nanxincun, Xiangshan, 100093 Beijing, China Xiaofang Sun, Key Laboratory of Vegetation and Environmental Change Institute of Botany, Chinese Academy of Sciences, No.20 Nanxincun, Xiangshan, 100093 Beijing, China Xingguo Han, Key Laboratory of Vegetation and Environmental Change Institute of Botany, Chinese Academy of Sciences, No.20 Nanxincun, Xiangshan, 100093 Beijing, China Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description:    Cadmium (Cd) toxicity inhibited the seedling growth while inducing the occurrences of lateral roots (LR) and adventitious roots (AR). Further study indicated that auxin and nitric oxide (NO) are involved in the processes. In this study, we chose model plant Arabidopsis thaliana and Cd-hyperaccumulator Solanum nigrum as material to examine the involvement of Cd-induced auxin redistribution in NO accumulation in plants and the effect of NO on Cd accumulation. For this aim, the histochemical staining, NO fluorescence probe (DAF-2DA) detections combined with the pharmacological study were used in this study. By using DR5:GUS staining analysis combined with NO fluorescence probe (DAF-2DA) detection, we found that Cd-induced NO accumulation is at least partly due to auxin redistribution in plants exposure to Cd. Supplementation with SNP donor S-nitrosoglutathione (GSNO) increased the number of LR and AR. In contrast, NO-scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethyl imidazoline-1-oxyl-3-oxide (cPTIO) reversed the effects of NO on modulating root system architecture and Cd accumulation. These results suggest that manipulation of the NO level is an effective approach to improve Cd tolerance in plants by modulating the development of LR and AR, and provide insights into novel strategies for phytoremediation. Content Type Journal Article Pages 1-13 DOI 10.1007/s11104-011-0800-4 Authors Jin Xu, Key Laboratory of Agricultural Water Resources, Center for Agricultural Resources Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Huaizhong RD 286, Shijiazhuang, 050021 China Wenying Wang, College of Life Science and Geography, Qinghai Normal University, Wusi west RD 38, Xining, 810008 China Jianhang Sun, Key Laboratory of Agricultural Water Resources, Center for Agricultural Resources Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Huaizhong RD 286, Shijiazhuang, 050021 China Yuan Zhang, College of Life Science, Jilin Agricultural University, Changchun, 130118 China Qing Ge, College of Life Science, Gansu Agricultural University, Lanzhou, 730070 China Liguo Du, Key Laboratory of Agricultural Water Resources, Center for Agricultural Resources Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Huaizhong RD 286, Shijiazhuang, 050021 China Hengxia Yin, College of Life Science and Geography, Qinghai Normal University, Wusi west RD 38, Xining, 810008 China Xiaojing Liu, Key Laboratory of Agricultural Water Resources, Center for Agricultural Resources Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Huaizhong RD 286, Shijiazhuang, 050021 China Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description:    Rhizosphere communities are critical to plant and ecosystem function, yet our understanding of the role of disturbance in structuring these communities is limited. We tested the hypothesis that soil contamination with petroleum hydrocarbons (PHCs) alters spatial patterns of ecto- (ECM) and ericoid (ERM) mycorrhizal fungal and root-associated bacterial community structure in the shared rhizosphere of pine ( Pinus contorta var. latifolia ) and lingonberry ( Vaccinium vitis-idaea ) in reconstructed sub-boreal forest soils. Pine seeds and lingonberry cuttings were planted into containers with an organic (mor humus, FH or coarse woody debris, CWD) layer overlying sandy mineral horizons (Ae and Bf) of forest soils collected from field sites in central British Columbia, Canada. After 4 months, 219 mg cm -2 crude oil was applied to the soil surface of half of the systems; systems were sampled 1 or 16 weeks later. Composition, relative abundance and vertical distribution of pine ECMs were assessed using light microscopy; community profiles were generated using LH-PCR of ribosomal DNA. Multivariate analysis revealed that plant and soil factors were more important determinants of community composition than was crude oil treatment. Fungal communities differed between pine and lingonberry roots; ECM communities were structured by soil layer whereas ERM communities varied between FH and CWD soil systems. Bacterial communities varied between plants and soil layers, indicating properties of ECM and ERM rhizospheres and the soil environment influence bacterial niche differentiation. This integration of mycorrhizal and bacterial community analysis contributes to a greater understanding of forest soil sustainability in forest ecosystems potentially contaminated with PHCs. Content Type Journal Article Pages 1-12 DOI 10.1007/s11104-011-0802-2 Authors Susan J. Robertson, Natural Resources and Environmental Studies, University of Northern British Columbia, 3333 University Way, Prince George, British Columbia V2N 4Z9, Canada P. Michael Rutherford, Environmental Science and Engineering, University of Northern British Columbia, 3333 University Way, Prince George, British Columbia V2N 4Z9, Canada Hugues B. Massicotte, Ecosystem Science and Management, University of Northern British Columbia, 3333 University Way, Prince George, British Columbia V2N 4Z9, Canada Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description:    Necessary and sufficient conditions for existence and uniqueness of solutions are developed for twofold saddle point problems which arise in mixed formulations of problems in continuum mechanics. This work extends the classical saddle point theory to accommodate nonlinear constitutive relations and the twofold saddle structure. Application to problems in incompressible fluid mechanics employing symmetric tensor finite elements for the stress approximation is presented. Content Type Journal Article Pages 1-31 DOI 10.1007/s00211-011-0372-5 Authors Jason S. Howell, Department of Mathematics, Clarkson University, Potsdam, NY 13676, USA Noel J. Walkington, Department of Mathematical Sciences, Carnegie Mellon University, Pittsburgh, PA 15213, USA Journal Numerische Mathematik Online ISSN 0945-3245 Print ISSN 0029-599X

Description:    The effects of flooding on rhizospheric organic acid concentrations of three abundant flooding tolerant plant species ( Alternanthera philoxeroides Mart., Arundinella anomala Steud., Salix variegata Franch.) from the water fluctuation zone of the Three Gorges Reservoir (TGR, Yangtze River) were investigated. Soil solution samples of eight low molecular weight organic acids were obtained from rhizotrons using micro suction cups during 3 weeks of waterlogging, after 6 weeks flooding and after a 1 week recovery. To estimate the contribution of water temperature and microbial community, plants in sterile glass bead substrate and original Yangtze sediment were submerged in laboratory at +10°, +20° and +30°C. Waterlogged plants did seldom express a significantly different pattern of rhizospheric organic acid (OA) composition compared to control plants. Flooding caused no burst of organic acid concentration in soil solution: All species express a silencing strategy. Average OA levels were higher in A. anomala rhizosphere than in the other two species, but increased again after resurfacing in all species. Temperature had a stronger influence in sediment than in sterile setup. In contrast to field measurements, succinate, malate and citrate were detected in the sterile setup. Microbial contribution appeared to have great influence on increasing OA occurrence. Content Type Journal Article Pages 1-19 DOI 10.1007/s11104-011-0732-z Authors Christina M. Schreiber, Key Laboratory of Eco-Environments in Three Gorges Reservoir Region (Ministry of Education), School of Life Sciences, Southwest China University, Chongqing, 400715 People’s Republic of China Bo Zeng, Key Laboratory of Eco-Environments in Three Gorges Reservoir Region (Ministry of Education), School of Life Sciences, Southwest China University, Chongqing, 400715 People’s Republic of China Vicky M. Temperton, Research Centre Juelich, IBG-2: Plant Sciences, 52425 Juelich, Germany Uwe Rascher, Research Centre Juelich, IBG-2: Plant Sciences, 52425 Juelich, Germany Marian Kazda, Institute of Systematic Botany and Ecology, University Ulm, 89069 Ulm, Germany Ulrich Schurr, Research Centre Juelich, IBG-2: Plant Sciences, 52425 Juelich, Germany Agnes Höltkemeier, Research Centre Juelich, IBG-3: Agrosphere, 52425 Juelich, Germany Arnd J. Kuhn, Research Centre Juelich, IBG-2: Plant Sciences, 52425 Juelich, Germany Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description:    The plasma membrane (PM) H + ATPase is involved in the plant response to nutrient deficiency. However, adaptation of this enzyme in monocotyledon plants to phosphorus (P) deficiency lacks direct evidence. In this study, we detected that P deficient roots of rice ( Oryza Sativa L.) could acidify the rhizosphere. We further isolated the PM from rice roots and analyzed the activity of PM H + ATPase. In vitro, P deficient rice roots showed about 30% higher activity of PM H + ATPase than the P sufficient roots at assay of pH 6.0. The P deficiency resulted in a decrease of the substrate affinity value ( K m ) of PM H + ATPase. The proton pumping activity of membrane vesicles from the P deficient roots was about 70% higher than that from P sufficient roots. Western blotting analysis indicated that higher activity of PM H + ATPase in P deficient roots was related to a slightly increase of PM H + ATPase protein abundance in comparison with that in P sufficient roots. Taken together, our results demonstrate that the P deficiency enhanced activities of both PM H + -ATPase and H + pump, which contributed to the rhizosphere acidification in rice roots. Content Type Journal Article Pages 1-9 DOI 10.1007/s11104-011-0774-2 Authors Ruiping Zhang, State Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, 210095 China Gan Liu, State Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, 210095 China Na Wu, State Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, 210095 China Mian Gu, State Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, 210095 China Houqing Zeng, State Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, 210095 China Yiyong Zhu, State Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, 210095 China Guohua Xu, State Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, 210095 China Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description:    The ancient landscape of the South - West Australian Floristic Region (SWAFR) is characterized by exceptional floristic diversity, attributed to a complex mosaic of nutrient - impoverished soils. Between - soil type differences in nutrient availability are expected to affect floristic assemblage patterns in the SWAFR. We compared patterns of floristic diversity between open - forest samples from three soil types in the high - rainfall zone of the SWAFR. The importance of environmental and spatial factors for species compositional turnover within soil types were evaluated within canonical correspondence analyses using variation partitioning. Patterns of phylogenetic diversity and dispersion were contrasted between soil types and related to differences in soil nutrient availability. Between - quadrat shared phylogenetic branch length for individual life form categories was correlated with explanatory variables using Mantel tests. Species and phylogenetic diversity increased with a decline in soil nutrients and basal area. Nutrient - poorer soils were differentiated by higher species density and phylogenetic diversity, and larger phylogenetic distances between species. Species turnover was best explained by environmental factors when soil nutrient concentrations and basal area were low. Coastal and inland quadrats from the most fertile soil type were distinguished by significantly differing patterns of phylogenetic diversity. Inland quadrats were characterized by strong relationships between phylogenetic diversity and environment, while phylogenetic patterns remained largely unaccounted for by explanatory variables within coastal quadrats. Phylogenetic diversity was more strongly related with environment within upland landform types for nutrient-poor soils. We highlight the complex relationships between climatic and edaphic factors within the SWAFR, and propose that the occurrence of refugial habitat for plant phylogenetic diversity is dynamically linked with these interactions. Climate change susceptibility was estimated to be especially high for inland locations within the high - rainfall zone. Despite the strong relationship between floristic diversity and soil fertility, holistic conservation approaches are required to conserve the mosaic of soil types regardless of soil nutrient status. Content Type Journal Article Pages 1-22 DOI 10.1007/s11104-011-0763-5 Authors Juliane Sander, School of Geography, Planning and Environmental Management, The University of Queensland, St Lucia, Queensland, Australia Grant Wardell-Johnson, School of Geography, Planning and Environmental Management, The University of Queensland, St Lucia, Queensland, Australia Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description:    Root systems are highly plastic as they express a range of responses to acquire patchily distributed nutrients. However, the ecological significance of placing roots selectively in nutrient hotspots is still unclear. Here, we investigate under what conditions selective root placement may be a significant functional trait that determines belowground competitive ability. We studied two grasses differing in root foraging behaviour, Festuca rubra and Anthoxanthum odoratum . The plants were grown in stable and more dynamic heterogeneous environments, by switching nutrient patches halfway through the experiment. A. odoratum was a factor of two less selective in placing its roots into nutrient-rich patches than F. rubra . A. odoratum produced overall higher root length densities with higher specific root length than F. rubra and acquired more nutrients. A. odoratum appeared to be the superior competitor, irrespective of the nutrient dynamics. Our results suggest that root behaviour consisting of producing high root length densities at relatively low biomass investments can be a more effective foraging strategy than placing roots selectively in nutrient hotspots. When understanding the functionality of root traits among different species, specific root length may play a key role. Content Type Journal Article Pages 1-14 DOI 10.1007/s11104-011-0752-8 Authors Liesje Mommer, Institute for Water and Wetland Research, Experimental Plant Ecology, Radboud University Nijmegen, P.O. box 9010, 6500 GL, Nijmegen, The Netherlands Eric J. W. Visser, Institute for Water and Wetland Research, Experimental Plant Ecology, Radboud University Nijmegen, P.O. box 9010, 6500 GL, Nijmegen, The Netherlands Jasper van Ruijven, Nature Conservation and Plant Ecology Group, Wageningen UR, P.O. box 47, 6700 AA Wageningen, The Netherlands Hannie de Caluwe, Institute for Water and Wetland Research, Experimental Plant Ecology, Radboud University Nijmegen, P.O. box 9010, 6500 GL, Nijmegen, The Netherlands Ronald Pierik, Plant Ecophysiology, Institute of Environmental Biology, Utrecht University, Padualaan 8, 3584 CH Utrecht, the Netherlands Hans de Kroon, Institute for Water and Wetland Research, Experimental Plant Ecology, Radboud University Nijmegen, P.O. box 9010, 6500 GL, Nijmegen, The Netherlands Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background and aims   The effects of drying and rewetting (DRW) have been studied extensively in non-saline soils, but little is known about the impact of DRW in saline soils. An incubation experiment was conducted to determine the impact of 1–3 drying and re-wetting events on soil microbial activity and community composition at different levels of electrical conductivity in the saturated soil extract (ECe) (ECe 0.7, 9.3, 17.6 dS m −1 ). Methods   A non-saline sandy loam was amended with NaCl to achieve the three EC levels 21 days prior to the first DRW; wheat straw was added 7 days prior to the first DRW. Each DRW event consisted of 1 week drying and 1 week moist (50% of water holding capacity, WHC). After the last DRW, the soils were maintained moist until the end of the incubation period (63 days after addition of the wheat straw). A control was kept moist (50% of WHC) throughout the incubation period. Results   Respiration rates on the day after rewetting were similar after the first and the second DRW, but significantly lower after the third DRW. After the first and second DRW, respiration rates were lower at EC17.6 compared to the lower EC levels, whereas salinity had little effect on respiration rates after the third DRW or at the end of the experiment when respiration rates were low. Compared to the continuously moist treatment, respiration rates were about 50% higher on day 15 (d15) and d29. On d44, respiration rates were about 50% higher at EC9.7 than at the other two EC levels. Cumulative respiration was increased by DRW only in the treatment with one DRW and only at the two lower EC levels. Salinity affected microbial biomass and community composition in the moist soils but not in the DRW treatments. At all EC levels and all sampling dates, the community composition in the continuously moist treatment differed from that in the DRW treatments, but there were no differences among the DRW treatments. Conclusions   Microbes in moderately saline soils may be able to utilise substrates released after multiple DRW events better than microbes in non-saline soil. However, at high EC (EC17.6), the low osmotic potential reduced microbial activity to such an extent that the microbes were not able to utilise substrate released after rewetting of dry soil. Content Type Journal Article Pages 1-11 DOI 10.1007/s11104-011-0918-4 Authors Nasrin Chowdhury, School of Agriculture, Food & Wine, The University of Adelaide, Adelaide, South Australia 5005, Australia Andre S. Nakatani, Universidade de São Paulo, ESALQ, Avenida Pádua Dias, 11, CEP 13418-900, Piracicaba, SP, Brazil Raj Setia, School of Agriculture, Food & Wine, The University of Adelaide, Adelaide, South Australia 5005, Australia Petra Marschner, School of Agriculture, Food & Wine, The University of Adelaide, Adelaide, South Australia 5005, Australia Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Erratum to: Prospects and problems of simple linear models for estimating symbiotic N 2 fixation by crop and pasture legumes Content Type Journal Article Pages 1-1 DOI 10.1007/s11104-011-0914-8 Authors M. J. Unkovich, Soil and Land Systems Group, Earth and Environmental Sciences, The University of Adelaide, Waite Campus, PMB 1, Glen Osmond, SA 5064, Australia J. Baldock, CSIRO Land and Water, PMB 2, Glen Osmond, SA 5064, Australia M. B. Peoples, CSIRO Plant Industry, GPO Box 1600, Canberra, ACT 2601, Australia Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Aims   We explored drivers of the spatial variability of plant carbon (C) and nitrogen (N) isotopes in the Los Angeles Basin and the implications of such plant isotopes for alterations to urban environments. Methods   We made simultaneous measurements of plant and soil isotopes, air pollutant concentrations, and soil N cycling. The common winter annual Bromus ( B . hordeaceus and B . madritensis ) and 0–10 cm soil were sampled at 13–15 sites located near air quality monitoring stations in 2008 and 2009. Results   The N isotopic composition (δ 15 N) of plants and soils were significantly correlated in both years. The plant-soil δ 15 N enrichment factor (EF), or the deviation of plant δ 15 N from soil δ 15 N, was positively correlated with nitrogen dioxide (NO 2 ) concentrations in 2008 but not in 2009. However, in 2009 plant EF decreased as the relative percentage of net nitrification in the soil (% net nitrification) increased up to 90%. Plant C isotopic composition (δ 13 C) was significantly and negatively correlated with soil moisture and with concentrations of atmospheric carbon monoxide (CO) and NO 2 . Conclusion   Urban plant isotopes may be used as indicators of altered environmental factors such as air pollution and also of soil N cycling. Content Type Journal Article Pages 1-16 DOI 10.1007/s11104-011-0912-x Authors Wenwen Wang, Department of Ecology and Evolutionary Biology, University of California, Irvine, Irvine, CA 92697-2525, USA Diane E. Pataki, Department of Earth System Science and Department of Ecology and Evolutionary Biology, University of California, Irvine, Irvine, CA 92697-3100, USA Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background and aims   Excessive accumulation of arsenic (As) in rice ( Oryza sativa L.) may pose a health risk to rice consumers. Long-distance transport of As within plant tissues is not well understood. The aim of our study was to evaluate As translocation from roots to shoots and from shoot tissues to rice grain. Methods   At the grain filling stage, 73 As-labelled arsenite was fed to roots, cut stems or flag leaves of rice. The root-feeding experiment also included a treatment of steam girdling near the base of panicle to block phloem transport. 73 As distribution in different tissues was quantified after 2 or 4 days. Results   In the root-feeding experiment, about 10% of the 73 As taken up was distributed to shoots mostly in stems and leaves, with 3.3% of the shoot 73 As found in the grain. Steam girdling decreased grain 73 As by 97%. In the stem-feeding experiment, most 73 As was retained in the stem with 3.9% distributed to the grain. In the flag leaf-feeding experiment, 12–15% of 73 As was exported to other tissues with 2–3% reaching the grain. Conclusions   As (mainly arsenite) has a relatively low mobility within rice plants. Arsenite was transported to rice grain mainly through the phloem. A small proportion of arsenite fed to flag leaves can be transported to grain. Content Type Journal Article Pages 1-8 DOI 10.1007/s11104-011-0926-4 Authors Fang-Jie Zhao, Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ, UK Jacqueline L. Stroud, Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ, UK M. Asaduzzaman Khan, Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ, UK Steve P. McGrath, Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ, UK Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Aims   Postfire logging recoups the economic value of timber killed by wildfire, but whether such forest management activity supports or impedes forest recovery in stands differing in structure from historic conditions remains unclear. The aim of this study was to determine the impact of mechanical logging after wildfire on soil bacterial and fungal communities and other measures influencing soil productivity. Methods   We compared soil bacterial and fungal communities and biogeochemical responses of 1) soils compacted, and 2) soils compacted and then subsoiled, to 3) soils receiving no mechanical disturbance, across seven stands, 1–3 years after postfire logging. Results   Compaction decreased plant-available N on average by 27% compared to no mechanical disturbance, while subsoiling decreased plant-available P (Bray) on average by 26% compared to the compacted and non-mechanically disturbed treatments. Neither bacterial nor fungal richness significantly differed among treatments, yet distinct separation by year in both bacterial and fungal community composition corresponded with significant increases in available N and available P between the first and second postharvest year. Conclusions   Results suggest that nutrients critical to soil productivity were reduced by mechanical applications used in timber harvesting, yet soil bacteria and fungi, essential to mediating decomposition and nutrient cycling, appeared resilient to mechanical disturbance. Results of this study contribute to the understanding about impacts of harvesting fire-killed trees and bear consideration along with the recovery potential of a site and the impending risk of future fire in stands with high densities of fire-killed trees. Content Type Journal Article Pages 1-19 DOI 10.1007/s11104-011-0925-5 Authors Tara N. Jennings, Department of Forest Ecosystems and Society, Oregon State University, Corvallis, OR 97331, USA Jane E. Smith, U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station, Forestry Sciences Laboratory, 3200 Jefferson Way, Corvallis, OR 97331, USA Kermit Cromack, Department of Forest Ecosystems and Society, Oregon State University, Corvallis, OR 97331, USA Elizabeth W. Sulzman, Department of Crop and Soil Science, Oregon State University, Corvallis, OR 97331, USA Donaraye McKay, U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station, Forestry Sciences Laboratory, 3200 Jefferson Way, Corvallis, OR 97331, USA Bruce A. Caldwell, Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331, USA Sarah I. Beldin, U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station, Forestry Sciences Laboratory, 3200 Jefferson Way, Corvallis, OR 97331, USA Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background and aims   Tecticornia species are stem-succulent, perennial halophytes (sub-family Salicornioideae; Chenopodiaceae) that inhabit saline areas including the margins of ephemeral salt lakes in Australia. Based on zonation observed at salt lakes, species were hypothesised to differ in tolerances to salinity and/or waterlogging. Methods   Three Tecticornia species were grown in sub-irrigated or waterlogged sand culture with treatments from 10 to 800 m M NaCl, for 60 d in a glasshouse. Growth, tissue solutes, root porosity, root radial O 2 loss, and ethanol production, were assessed. Results   The three species were salt tolerant; at 800 m M NaCl shoot RGR (ash-free) was reduced by 9% in T. indica , 22% in T. pergranulata and 39% in T. mellaria . Na + and Cl − were the predominant osmotica in succulent stem tissues. Glycinebetaine was a major organic solute. T. pergranulata and T. indica were waterlogging tolerant; shoot RGR was reduced by at most 29% irrespective of salinity. Waterlogging tolerance in T. mellaria was variable (shoot RGR 8%–56% of controls) and some individuals died. T. pergranulata formed adventitious roots with aerenchyma, but the two other species did not. Anoxic tips of lateral roots produced ethanol. Conclusion   The three Tecticornia species are salt tolerant. T. pergranulata is also waterlogging tolerant and formed adventitious roots containing aerenchyma, traits consistent with growth on mud flats of salt lakes. T. indica was unexpectedly tolerant of waterlogging, whereas T. mellaria was less tolerant. Future work is needed to evaluate tolerances of inundation (i.e. submergence) and to higher salinity treatments. Content Type Journal Article Pages 1-18 DOI 10.1007/s11104-011-0924-6 Authors Jeremy P. English, School of Plant Biology (M084), The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia Timothy D. Colmer, School of Plant Biology (M084), The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Introduction   Proper understanding of how rate of OM decomposition varies across a given watershed is important to determine the potential of soil erosion to induce terrestrial carbon (C) sequestration. However, as of yet, our understanding of the spatial variability of rate of organic matter (OM) decomposition ( k ) across a watershed is incomplete, at best. Aim   The objective of this study is to determine how rates of organic substrate decomposition vary on the surface and in soil profiles of eroding vs. depositional landform positions. Methods   To determine rate of organic substrate decomposition in eroding vs. depositional landform positions, a field litterbag decomposition study was conducted in Tennessee Valley, Northern California using in situ foliage (from grasses and a shrub) and two standard substrates (filter paper and birch tongue depressors, that served as proxies for OM that is relatively easier vs. harder to breakdown during microbial decomposition). We conducted the experiment at 3–4 depths at each landform position. Results   The effect of erosional transport (surface to surface transfer of topsoil and associated SOM from eroding to depositional landform positions) and burial (after deposition of eroded SOM by successive erosional events) on decomposition rate of eroded SOM was different depending on the nature of eroding and depositional landform positions considered. The k of organic substrates at 25 cm soil depth in the depositional positions was up to 2 orders of magnitude higher than on the surface of the eroding positions. Results of this litterbag decomposition study suggest that transport of SOM from topsoil of eroding positions to the surface of depositional positions can reduce its k ; but burial of eroded SOM in soil profiles at the depositional positions can lead to increasing k . Conclusion   Because erosion-induced C sequestration is a function of changes in rate of OM decomposition and input post-compared to pre-erosion, our findings suggest that higher rates of plant productivity in eroding watersheds is needed to create and maintain a C sink in such eroding watersheds. Content Type Journal Article Pages 1-20 DOI 10.1007/s11104-011-0902-z Authors Asmeret Asefaw Berhe, School of Natural Sciences, University of California, Merced, 4225 N. Hospital Rd, Castle # 47, Atwater, CA 95301, USA Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background   The eutrophication of aquatic systems due to diffuse pollution of agricultural phosphorus (P) is a local, even regional, water quality problem that can be found world-wide. Scope   Sustainable management of P requires prudent tempering of agronomic practices, recognizing that additional steps are often required to reduce the downstream impacts of most production systems. Conclusions   Strategies to mitigate diffuse losses of P must consider chronic (edaphic) and acute, temporary (fertilizer, manure, vegetation) sources. Even then, hydrology can readily convert modest sources into significant loads, including via subsurface pathways. Systemic drivers, particularly P surpluses that result in long-term over-application of P to soils, are the most recalcitrant causes of diffuse P loss. Even in systems where P application is in balance with withdrawal, diffuse pollution can be exacerbated by management systems that promote accumulation of P within the effective layer of effective interaction between soils and runoff water. Indeed, conventional conservation practices aimed at controlling soil erosion must be evaluated in light of their ability to exacerbate dissolved P pollution. Understanding the opportunities and limitations of P management strategies is essential to ensure that water quality expectations are realistic and that our beneficial management practices are both efficient and effective. Content Type Journal Article Pages 1-14 DOI 10.1007/s11104-011-0832-9 Authors Peter J. A. Kleinman, USDA-ARS, Pasture Systems and Watershed Management Research Unit, University Park, PA, USA Andrew N. Sharpley, Department of Crop, Soil and Environmental Sciences, University of Arkansas, Fayetteville, AR, USA Richard W. McDowell, AgResearch, Ltd., Invermay Agricultural Centre, Mosgiel, New Zealand Don N. Flaten, Department of Soil Science, University of Manitoba, Winnipeg, Manitoba, Canada Anthony R. Buda, USDA-ARS, Pasture Systems and Watershed Management Research Unit, University Park, PA, USA Liang Tao, Chinese Academy of Sciences, Institute of Geographic Sciences and Natural Resources, Beijing, China Lars Bergstrom, Department of Soil Science, Swedish University of Agricultural Sciences, Uppsala, Sweden Qing Zhu, USDA-ARS, Pasture Systems and Watershed Management Research Unit, University Park, PA, USA Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background   Arbuscular mycorrhizal (AM) fungi contribute to plant nutrient uptake in systems managed with reduced fertilizer and pesticide inputs such as organic agriculture by extending the effective size of the rhizosphere and delivering minerals to the root. Connecting the molecular study of the AM symbiosis with agriculturally- and ecologically-relevant field environments remains a challenge and is a largely unexplored research topic. Methods   This study utilized a cross-disciplinary approach to examine the transcriptional, metabolic, and physiological responses of tomato ( Solanum lycopersicum ) AM roots to a localized patch of nitrogen (N). A wild-type mycorrhizal tomato and a closely-related non-mycorrhizal mutant were grown at an organic farm in soil that contained an active AM extraradical hyphal network and soil microbe community. Results   The majority of genes regulated by upon enrichment of nitrogen were similarly expressed in mycorrhizal and non-mycorrhizal roots, suggesting that the primary response to an enriched N patch is mediated by mycorrhiza-independent root processes. However where inorganic N concentrations in the soil were low, differential regulation of key tomato N transport and assimilation genes indicate a transcriptome shift towards mycorrhiza-mediated N uptake over direct root supplied N. Furthermore, two novel mycorrhizal-specific tomato ammonium transporters were also found to be regulated under low N conditions. A conceptual model is presented integrating the transcriptome response to low N and highlighting the mycorrhizal-specific ammonium transporters. Conclusions   These results enhance our understanding of the role of the AM symbiosis in sensing and response to an enriched N patch, and demonstrate that transcriptome analyses of complex plant-microbe-soil interactions provide a global snapshot of biological processes relevant to soil processes in organic agriculture. Content Type Journal Article Pages 1-18 DOI 10.1007/s11104-011-0890-z Authors Daniel R. Ruzicka, Donald Danforth Plant Science Center, 975 N Warson Rd., St. Louis, MO 63132, USA Natasha T. Hausmann, Department of Land, Air, and Water Resources, University of California, 1 Shields Avenue, Davis, CA 95616, USA Felipe H. Barrios-Masias, Department of Land, Air, and Water Resources, University of California, 1 Shields Avenue, Davis, CA 95616, USA Louise E. Jackson, Department of Land, Air, and Water Resources, University of California, 1 Shields Avenue, Davis, CA 95616, USA Daniel P. Schachtman, Donald Danforth Plant Science Center, 975 N Warson Rd., St. Louis, MO 63132, USA Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Aims   This study aimed to determine whether white lupin adaptation to moderately calcareous soils could be enhanced by lime-tolerant plants and Bradyrhizobium strains. Methods   Fourteen landraces from Italy, Morocco and Egypt and some cultivars were grown in moderate-lime (ML) and low-lime (LL) soil with each of two inoculants, one commercial and one including three Bradyrhizobium strains well-nodulating under ML soil (isolated from other lupin species). Grain yield and above-ground biomass were assessed in large artificial environments that mimicked field conditions. Shoot, root and nodulation traits at onset of flowering were studied in a pot experiment. Results   ML soil severely reduced plant yield, growth and nodulation but increased the harvest index relative to LL. Top-yielding genotypes for grain yield displayed significant rank inversion across soil types (P 〈 0.05). Lime-tolerant genotypes reduced their nodulation in ML soil less than limesusceptible ones. Some landraces outperformed the reference lime-tolerant cultivar Giza 1 in ML soil. One Italian landrace had a lime-tolerant response across agricultural locations. The Moroccan inoculant provided greater nodulation, more shoot residues but similar grain yield in ML soil, and less grain and shoot residues in LL soil, compared with the commercial inoculant. Conclusions   Lupin adaptation to ML soil can be improved mainly through selection of lime-tolerant plants. Content Type Journal Article Pages 1-14 DOI 10.1007/s11104-011-0889-5 Authors Paolo Annicchiarico, CRA-Centro di Ricerca per le Produzioni Foraggere e Lattiero-Casearie, viale Piacenza 29, 26900 Lodi, Italy Imane Thami Alami, Institut National de la Recherche Agronomique (INRA), Avenue de la Victoire, BP 415 Rabat, Morocco Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Aims   Temperate grassland is one of the major global biome types and is widely used as rangeland. Typically, cold winters are followed by a transition period with soil thawing that may last from days to weeks. Pulse N 2 O emissions during freeze-thaw events have been observed in a range of temperate ecosystem types and may contribute significantly to annual N 2 O emissions. It was shown recently that spring thaw pulse N 2 O emissions dominated annual N 2 O emissions in a steppe region of Inner Mongolia. Even though biogeochemical models are increasingly used for up scaling of N 2 O emissions from terrestrial ecosystems, they still need to be further developed to be capable of both simulating pulse N 2 O emission during spring thaw and accounting for the impact of grazing on soil N 2 O emissions in general. Methods   In this study, we modified an existing biogeochemical model, Mobile-DNDC, to allow an improved simulation of plant production, snow height, and soil moisture for steppe in Inner Mongolia exposed to different grazing intensities. The newly introduced routines relate maximum snow height to end-of-season biomass (ESSB), to account for decreased plant productivity due to grazing and consider the increase of resistance (impedance) of soil ice on the soil hydraulic conductivity. Results   The implementation of the impedance concept, which means the consideration of decreased hydraulic conductivity in frozen soil, resulted in an improved simulation of soil water content and decreased simulated oxygen content in the top soil during freeze-thaw periods. Increased soil moisture and associated oxygen limitation stimulated N 2 O emission by enhanced denitrification. Based on observations in the field, maximum snow height was limited by ESSB, protecting snow against erosion by wind. Since grazing reduced biomass and thereby snow cover, water availability during spring thaw was smaller at grazed sites as compared to ungrazed sites. In agreement with field observations, lower water content and anaerobiosis resulted in decreased N 2 O emissions during spring thaw. Conclusions   The introduction of the impedance concept into Mobile-DNDC is a major step forward in simulating pulse N 2 O emissions from soils during spring-thaw. Content Type Journal Article Pages 1-14 DOI 10.1007/s11104-011-0908-6 Authors Benjamin Wolf, Institute for Meteorology and Climate Research (IMK-IFU), Karlsruher Institute of Technology, Kreuzeckbahnstrasse 19, 82467 Garmisch-Partenkirchen, Germany Ralf Kiese, Institute for Meteorology and Climate Research (IMK-IFU), Karlsruher Institute of Technology, Kreuzeckbahnstrasse 19, 82467 Garmisch-Partenkirchen, Germany Weiwei Chen, State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute for Atmospheric Physics, Chinese Academy of Sciences (IAP-CAS), 100029 Beijing, China Rüdiger Grote, Institute for Meteorology and Climate Research (IMK-IFU), Karlsruher Institute of Technology, Kreuzeckbahnstrasse 19, 82467 Garmisch-Partenkirchen, Germany Xunhua Zheng, State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute for Atmospheric Physics, Chinese Academy of Sciences (IAP-CAS), 100029 Beijing, China Klaus Butterbach-Bahl, Institute for Meteorology and Climate Research (IMK-IFU), Karlsruher Institute of Technology, Kreuzeckbahnstrasse 19, 82467 Garmisch-Partenkirchen, Germany Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background and Aims   This study investigated initial land-use change effects on ecosystem biomass, carbon (C) and nitrogen (N) allocation and storage by comparing a recently afforested grassland with an adjacent intensively managed grassland in southern Ireland. Methods   Soil C, N and fine root (〈2 mm) stocks were determined from soil cores. Above ground biomass, C and N stocks were estimated from biomass clipping, inventory and allometric biomass equations developed for ash ( Fraxinus excelsior L.) and black alder ( Alnus glutinosa L.) in the 5-year-old forest plantation. Results   Five years after grassland afforestation, the mean fine root stock of 0.31 kg m −2 in the forest was about half that of 0.64 kg m −2 in the grassland. This decrease was offset by an additional gain of 0.36 kg m −2 in tree biomass since afforestation. The above- to below ground biomass ratio shifted from 0.20 in the grassland to 1.59 in the forest. From May to October, mean net N mineralization was significantly lower in the forest compared to the grassland. Soil C and N concentrations in the 0–10 cm soil layer were significantly higher in the forest (62 mg C g −1 ; 5.7 mg N g −1 ) compared to the grassland (45 mg C g −1 ; 3.6 mg N g −1 ). However, the bulk density in the upper forest soil layer was lower than in the grassland. As a result, no differences existed between the respective total (0–30 cm depth) soil C and N stocks. Total ecosystem C and N storage was also similar for the forest (9.5 kg C m −2 ; 0.75 kg N m −2 ) and the grassland (9.3 kg C m −2 ; 0.77 kg N m −2 ). Conclusions   A significant change in total ecosystem C and N following afforestation of this intensively managed grassland was not observed. Nevertheless, this study highlights immediate implications from such land-use change activities on biomass, C and N reallocation among the above- and belowground ecosystem pools which may subsequently affect ecosystem biogeochemical cycles. Content Type Journal Article Pages 1-16 DOI 10.1007/s11104-011-0905-9 Authors Matthias Peichl, Center for Hydrology, Micrometeorology & Climate Change, Department of Civil and Environmental Engineering, University College Cork, Cork, Republic of Ireland Natalie Anne Leava, Center for Hydrology, Micrometeorology & Climate Change, Department of Civil and Environmental Engineering, University College Cork, Cork, Republic of Ireland Gerard Kiely, Center for Hydrology, Micrometeorology & Climate Change, Department of Civil and Environmental Engineering, University College Cork, Cork, Republic of Ireland Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Aims   A key issue related to the usefulness of the minirhizotron technique is whether root presence and behaviour in the soil zone at the minirhizotron interface are consistent with those in the bulk soil. We wanted to test the null hypotheses that there were no differences in root densities or specific root length (SRL) between those positions. The effects of different nutrient and water regimes, and different tree species (grey alder and basket willow) on the root variables were also examined. Methods   We quantified root mass and length densities, and calculated SRL, of three diameter classes from cores sampled around minirhizotrons and in the bulk soil, i.e. quartz sand. Fine root dynamics were monitored in the minirhizotrons during three consecutive years prior to sampling. The study was conducted on individual root systems within buried and covered lysimeters, placed in a stand structure, and with different water and nutrient regimes. Results   Significant discrepancies in root densities were found between positions. Plants subjected to limited water or nutrient supply had up to three times higher densities at the minirhizotrons. However, effects of species and treatments showed a similar pattern for the diameter class 〈1 mm between the two sampling positions and minirhizotron observations. The pulses of fine root growth and decay were coordinated in time for both species and treatments. The SRL was not affected by the tube in any diameter class. Conclusions   We concluded that the minirhizotron technique alone was of limited use for estimating root densities in the bulk soil. But the results showed that minirhizotrons could be useful, for example, combined with soil coring or in comparative studies. The patterns of fine root growth and decay were similar for species and treatments, and SRL was unaffected, suggesting that minirhizotrons can be used in studies of root dynamics and morphology. There is, however, a need for further studies concerning the influence on root survival and decay. Content Type Journal Article Pages 1-16 DOI 10.1007/s11104-011-0896-6 Authors Rose-Marie Rytter, Rytter Science, Backavägen 16, SE-26868 Röstånga, Sweden Lars Rytter, Rytter Science, Backavägen 16, SE-26868 Röstånga, Sweden Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background and Aims:   The idea of immobilizing Fe and the formation of a slow-release fertilizer has been considered in several studies. However, none of the proposed materials were found efficient in correcting Fe deficiency. In the present study immobilization of Fe chelates on a solid matrix, as a first step in the production and supply process, is tested. Methods:   The free forms of the siderophores desferrioxamine B (DFOB) and ethylendiaminebis( o -hydroxyphenyl-acetic acid) (EDDHA) were immobilized on p -nitrophenylchloroformate activated Sepharose and tested as Fe source for both strategy I (peanuts and cucumber, Arachis hypogeae L. and Cucumis sativus L., respectively) and strategy II (barley and wheat, Hordeum vulgare L. and Triticum aestivum L., respectively), plants. Plants grown in hydroponic cultures at pH 7.3 were supplied with the immobilized Fe-chelate either free in solution or confined in a dialysis tube with or without EDDHA in the outer solution as a carrier. Results:   Cucumber and barley plants were found efficient in acquiring Fe from the immobilized chelates. Conclusions:   The effectiveness in utilizing the immobilized Fe-chelate differed among cultivars and was related to the efficiency of the reductases activity or phytosiderophores secretion systems, in Strategy I and Strategy II plants, respectively. Content Type Journal Article Pages 1-13 DOI 10.1007/s11104-011-0923-7 Authors Zehava Yehuda, Department of Soil and Water Sciences, Robert H. Smith Faculty of Agriculture Food and Environment, The Hebrew University of Jerusalem, P.O.B. 12, Rehovot, 76100 Israel Yitzhak Hadar, Department of Plant Pathology and Microbiology, Robert H. Smith Faculty of Agriculture Food and Environment, The Hebrew University of Jerusalem, P.O.B. 12, Rehovot, 76100 Israel Yona Chen, Department of Soil and Water Sciences, Robert H. Smith Faculty of Agriculture Food and Environment, The Hebrew University of Jerusalem, P.O.B. 12, Rehovot, 76100 Israel Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background   Biochar’s role as a carbon sequestration agent, while simultaneously providing soil fertility improvements when used as an amendment, has been receiving significant attention across all sectors of society, ranging from academia, industry, government, as well as the general public. This has lead to some exaggeration and possible confusion regarding biochar’s actual effectiveness as a soil amendment. One sparsely explored area where biochar appears to have real potential for significant impact is the soil nitrogen cycle. Scope   Taghizadeh-Toosi et al. (this issue) examined ammonia sorption on biochar as a means of providing a nitrogen-enriched soil amendment. The longevity of the trapped ammonia was particularly remarkable; it was sequestered in a stable form for at least 12 days under laboratory air flow. Furthermore, the authors observed increased 15 N uptake by plants grown in soil amended with the 15 N-enriched biochar, indicating that the 15 N was not irreversibly bound, but, was plant-available. Conclusions   Their observations add credence to utilizing biochar as a carrier for nitrogen fertilization, while potentially reducing the undesired environmental consequences through gas emissions, overland flow, and leaching. Content Type Journal Article Pages 1-8 DOI 10.1007/s11104-011-0930-8 Authors Kurt A. Spokas, USDA-ARS, Soil and Water Management Unit, 1991 Upper Buford Circle – 439 Borlaug Hall, St. Paul, MN 55108, USA Jeff M. Novak, USDA-ARS, Coastal Plains Soil, Water, and Plant Research Center, 2611 W. Lucas Street, Florence, SC 29501, USA Rodney T. Venterea, USDA-ARS, Soil and Water Management Unit, 1991 Upper Buford Circle – 439 Borlaug Hall, St. Paul, MN 55108, USA Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Aims   To study the relationship between changes in soil properties and plant community characters produced by grazing in a meadow steppe grassland and the composition and diversity of spore-producing arbuscular mycorrhizal fungi (AMF). Methods   A field survey was carried out in a meadow steppe area with a gradient of grazing pressures (a site with four grazing intensities and a reserve closed to grazing). The AMF community composition (characterized by spore abundance) and diversity, the vegetation characters and soil properties were measured, and root colonization by AMF was assessed. Results   AMF diversity (richness and evenness) was higher under light to moderate grazing pressure and declined under intense grazing pressures. Results of multiple regressions indicated that soil electrical conductivity was highly associated with AMF diversity. The variation in AMF diversity was partially associated to the density of tillers of the dominant grass ( Leymus chinensis ), the above and below-ground biomass and the richness of the plant community. Conclusions   We propose that the relationship between plants and AMF is altered by environmental stress (salinity) which is in turn influenced by animal grazing. Direct and indirect interactions between vegetation, soil properties, and AMF community need to be elucidated to improve our ability to manage these communities. Content Type Journal Article Category Regular Article Pages 1-14 DOI 10.1007/s11104-011-0985-6 Authors Lei Ba, Institute of Grassland Science, Northeast Normal University, Key Laboratory of Vegetation Ecology, Ministry of Education, Changchun, 130024 People’s Republic of China Jiaxu Ning, Institute of Grassland Science, Northeast Normal University, Key Laboratory of Vegetation Ecology, Ministry of Education, Changchun, 130024 People’s Republic of China Deli Wang, Institute of Grassland Science, Northeast Normal University, Key Laboratory of Vegetation Ecology, Ministry of Education, Changchun, 130024 People’s Republic of China Evelina Facelli, School of Agriculture Food and Wine, The University of Adelaide, Adelaide, SA, Australia José M. Facelli, School of Earth and Environmental Science, The University of Adelaide, Adelaide, SA, Australia Yaning Yang, Institute of Grassland Science, Northeast Normal University, Key Laboratory of Vegetation Ecology, Ministry of Education, Changchun, 130024 People’s Republic of China Lichao Zhang, Institute of Grassland Science, Northeast Normal University, Key Laboratory of Vegetation Ecology, Ministry of Education, Changchun, 130024 People’s Republic of China Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description:    Recently, the format of TT tensors (Hackbusch and Kühn in J Fourier Anal Appl 15:706–722, 2009 ; Oseledets in SIAM J Sci Comput 2009 , submitted; Oseledets and Tyrtyshnikov in SIAM J Sci Comput 31:5, 2009 ; Oseledets and Tyrtyshnikov in Linear Algebra Appl 2009 , submitted) has turned out to be a promising new format for the approximation of solutions of high dimensional problems. In this paper, we prove some new results for the TT representation of a tensor U Î \mathbb R n 1 × ¼ × n d and for the manifold of tensors of TT-rank r . As a first result, we prove that the TT (or compression) ranks r i of a tensor U are unique and equal to the respective separation ranks of U if the components of the TT decomposition are required to fulfil a certain maximal rank condition. We then show that the set \mathbb T of TT tensors of fixed rank r locally forms an embedded manifold in \mathbb R n 1 × ¼ × n d , therefore preserving the essential theoretical properties of the Tucker format, but often showing an improved scaling behaviour. Extending a similar approach for matrices (Conte and Lubich in M2AN 44:759, 2010 ), we introduce certain gauge conditions to obtain a unique representation of the tangent space T U \mathbb T of \mathbb T and deduce a local parametrization of the TT manifold. The parametrisation of T U \mathbb T is often crucial for an algorithmic treatment of high-dimensional time-dependent PDEs and minimisation problems (Lubich in From quantum to classical molecular dynamics: reduced methods and numerical analysis, 2008 ). We conclude with remarks on those applications and present some numerical examples. Content Type Journal Article Pages 1-31 DOI 10.1007/s00211-011-0419-7 Authors Sebastian Holtz, TU Berlin, Straße des 17. Juni 136, 10623 Berlin, Germany Thorsten Rohwedder, TU Berlin, Straße des 17. Juni 136, 10623 Berlin, Germany Reinhold Schneider, TU Berlin, Straße des 17. Juni 136, 10623 Berlin, Germany Journal Numerische Mathematik Online ISSN 0945-3245 Print ISSN 0029-599X

Description: Background and Aims   In line with the Stress Gradient Hypothesis, studies of facilitation have tended to focus on plant–plant interactions (biotic nurses), while the relative role of abiotic nurses has been little studied. We assessed the role of biotic and abiotic nurses, and their interaction, on soil enhancement and the consequential performance of a native annual grass, Dactyloctenium radulans . Methods   We used a growth chamber study with two levels of water application to compare the performance of D. radulans growing in soil from foraging pits of the Short-beaked echidna ( Tachyglossus aculeatus ; abiotic nurse) and non-pit soil from either under tree canopies (biotic nurse) or surrounding open areas. Results   All measures of plant performance were more pronounced under the high than the low water treatment. The greatest differences between pit and surface Microsites occurred under the low water application, reinforcing our view that facilitatory effects are greater in resource-limited environments. Despite tree canopy soil having greater N, there was no significant effect on plant performance, nor any significant interaction with Microsite. Conclusions   Our study provides strong evidence that foraging pits enhance soil properties and this soil, in turn, facilitates plant growth; and supports previous work documenting the positive effect of nurse-protégé interactions under greater levels of abiotic stress. Content Type Journal Article Category Regular Article Pages 1-11 DOI 10.1007/s11104-011-1000-y Authors Samantha K. Travers, Evolution and Ecology Research Centre, School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, NSW 2052, Australia David J. Eldridge, Evolution and Ecology Research Centre, School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, NSW 2052, Australia Terry B. Koen, Office of Environment and Heritage, P.O. Box 445, Cowra, NSW 2794, Australia Santiago Soliveres, Área de Biodiversidad y Conservación, Departamento de Biología y Geología, Escuela Superior de Ciencias Experimentales y Tecnología, Universidad Rey Juan Carlos, 28933 Móstoles, Spain Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background and aims   Soils derived from serpentinite (serpentine soils) often have low macronutrient concentrations, exceedingly low Ca:Mg molar ratios and high heavy metal concentrations, typically resulting in sparse vegetative cover. This combined suite of edaphic stresses is referred to as the “serpentine syndrome.” Although several plant community-level studies have been conducted to identify the most important edaphic factor limiting plant growth on serpentine, the primary factor identified has often varied by plant community and local climate. Few studies to date have been conducted in serpentine plant communities of alpine or boreal climates. The goal of our study was to determine the primary limiting edaphic factors on plant community species composition and productivity (cover) in the alpine and boreal climate of the Western Alps, Italy. Methods   Soil properties and vegetation composition were analyzed for several sites underlain by serpentinite, gabbro, and calc-schist substrates and correlated using direct and indirect statistical methods. Results   Boreal forest soils were well-developed and tended to have low pH throughout the soil profile resulting in high Ni availability. Alpine soils, in comparison, were less developed. The distinct serpentine plant communities of the Western Alps are most strongly correlated with high levels of bioavailable Ni associated with low soil pH. Other factors such as macronutrient deficiency, low Ca:Mg molar ratio and drought appear to be less important. Conclusions   The strong ecological influence of Ni is caused by environmental conditions which increase metal mobilization. Content Type Journal Article Category Regular Article Pages 1-23 DOI 10.1007/s11104-011-0932-6 Authors Michele E. D’Amico, Department of Environmental Sciences, University of Milano Bicocca, Piazza della Scienza 1, 20126 Milan, Italy Franco Previtali, Department of Environmental Sciences, University of Milano Bicocca, Piazza della Scienza 1, 20126 Milan, Italy Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Aims   The aim of the present study was to compare lead accumulation and tolerance among heavy metal hyperaccumulating and non-hyperaccumulating metallophytes. Methods   To this purpose, we compared Pb tolerance and accumulation in hydroponics among calamine and non-calamine populations of Silene vulgaris , Noccaea caerulescens , and Matthiola flavida . We established the effects of Ca on Pb tolerance and accumulation in M. flavida , and measured exchangeable soil Pb and Ca at two calamine sites. Results   Results revealed that calamine populations of S. vulgaris and N. caerulescens were Pb hypertolerant, but the calamine M. flavida population was not. Pb hyperaccumulation capacity was exclusively found in one of the calamine N. caerulescens populations. Conclusions   1) Pb hypertolerance is sometimes lacking in metallophyte populations from strongly Pb-enriched soil, probably due to a relatively high level of exchangeable soil Ca, 2) Ca effectively counteracts Pb uptake and Pb toxicity, 3) The tendency to hyperaccumulate Pb is a population-specific phenomenon in N. caerulescens , 4) Pb hypertolerance in N. caerulescens is not necessarily associated with a tendency to hyperaccumulate Pb, 5) apparent natural Pb hyperaccumulation in M. flavida is not reproducible in hydroponics, probably due to the absence of air-born contamination in laboratory experiments. Content Type Journal Article Category Regular Article Pages 1-10 DOI 10.1007/s11104-011-0994-5 Authors Ahmad Mohtadi, Department of Biology, University of Isfahan, Isfahan, 81746-73441 Iran Seyed Majid Ghaderian, Department of Biology, University of Isfahan, Isfahan, 81746-73441 Iran Henk Schat, Department of Genetics, Faculty of Earth and Life Sciences, Vrije Universiteit Amsterdam, De Boelelaan 1085, 1081 HV Amsterdam, The Netherlands Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Aims and methods   Concentrations of heavy metals such as Cd, As, Hg, Pb, Cr, Cu, Zn and Ni in different tissues (seeds, roots and shoots) of the mature canola ( Brassica napus L. ) plants and in the associated rhizosphere soils from Yangtze River Delta (YRD) region of China, were determined to evaluate the heavy metals’ pollution in the soils and the canola seeds, and to discuss their accumulation and translocation characteristics in canola plants. At the same time, the phytoextraction potential of the canola plant for the above heavy metals was theoretically calculated and discussed on the basis of above measured data. Results   The results showed that the concentration ranges of Cd, As, Hg, Pb, Cr, Cu, Zn and Ni in the rhizosphere soils were 0.115–0.481, 3.40–20.5, 0.069–0.682, 9.92–27.4, 46.8–86.6, 17.7–253.3, 65.2–511.7 and 16.0–37.8 mg kg −1 , respectively. The concentrations of Cu, Zn and Hg at some sampling sites exceeded the 2nd grade threshods of Chinese national environmental quality standard for soils. The potential ecological risk of heavy metals in the canola rhizosphere soils decreased in the order of Zhejiang 〉 Shanghai 〉 Jiangsu provinces. The concentration ranges of above heavy metals in the canola seeds were 0.032–0.067, 0.002–0.005, 0.001–0.005, 0.053–0.165, 0.191–0.855, 3.01–13.20, 34.82–96.95 and 0.343–2.86 mg kg −1 , respectively, with Cu and Zn at some sampling sites exceeding the permissible concentrations in foods of China. Heavy metals’ concentrations in canola seeds didn’t increase with their increasing concentrations in the rhizosphere soils. The bioconcentration factors (BCFs) of most heavy metals in the canola seeds decreased with their increasing concentrations in the associated rhizosphere soils. The average BCFs of heavy metals decreased in the order of Zn (0.488)〉Cd (0.241)〉Cu (0.145)〉Ni (0.038)〉Hg (0.021)〉Pb (0.005)=Cr (0.005)〉As (0.000) in the canola seeds, Cd (1.550)〉Cu (0.595)〉Zn (0.422)〉Hg (0.138)〉Ni (0.085)〉Pb (0.080)〉As (0.035)〉Cr (0.031) in the roots, and Cd (0.846)〉Zn (0.242)〉Cu (0.205)〉Hg (0.159)〉Ni (0.031)〉Pb (0.025)〉As (0.012)〉Cr (0.007) in the shoots, respectively. The accumulation capacity for most of the above heavy metals in the mature canola tissues was root 〉 shoot 〉 seed, with the exceptions of seed 〉 root 〉 shoot for Zn and shoot 〉 root 〉 seed for Hg. Except Hg from root to shoot and Zn from root to seed, translocation factors (TFs) of above heavy metals were lower than 1.0. Conclusions   The concentrations, BCFs and TFs of above heavy metals in the canola tissues indicated that the investigated canola plants did not meet the criteria of hyperaccumulators for the above heavy metals. The phytoextracton potential of the studied canola plants for the above heavy metals from the polluted soils was very limited. It would take 920, 3,170 and 3,762 years (assuming two crops per year) to reduce the initial soil Zn, Cu and Hg concentrations, respectively, from the most polluted soil concentrations to the 2nd grade thresholds of Chinese national environmental quality standard for soils. Content Type Journal Article Category Regular Article Pages 1-13 DOI 10.1007/s11104-011-1006-5 Authors Ruilian Yu, Institute of Surficial Geochemistry, School of Earth Sciences and Engineering, Nanjing University, Nanjing, 210093 China Junfeng Ji, Institute of Surficial Geochemistry, School of Earth Sciences and Engineering, Nanjing University, Nanjing, 210093 China Xuyin Yuan, College of Environment, Hohai University, Nanjing, 210098 China Yinxian Song, Institute of Surficial Geochemistry, School of Earth Sciences and Engineering, Nanjing University, Nanjing, 210093 China Cheng Wang, Institute of Surficial Geochemistry, School of Earth Sciences and Engineering, Nanjing University, Nanjing, 210093 China Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background and aims   Changes in soil moisture availability seasonally and as a result of climatic variability would influence soil nitrogen (N) cycling in different land use systems. This study aimed to understand mechanisms of soil moisture availability on gross N transformation rates. Methods   A laboratory incubation experiment was conducted to evaluate the effects of soil moisture content (65 vs. 100% water holding capacity, WHC) on gross N transformation rates using the 15 N tracing technique (calculated by the numerical model FLUAZ) in adjacent grassland and forest soils in central Alberta, Canada. Results   Gross N mineralization and gross NH 4 + immobilization rates were not influenced by soil moisture content for both soils. Gross nitrification rates were greater at 100 than at 65% WHC only in the forest soil. Denitrification rates during the 9 days of incubation were 2.47 and 4.91 mg N kg -1 soil d -1 in the grassland and forest soils, respectively, at 100% WHC, but were not different from zero at 65% WHC. In the forest soil, both the ratio of gross nitrification to gross NH 4 + immobilization rates (N/IA) and cumulative N 2 O emission were lower in the 65 than in the 100% WHC treatment, while in the grassland soil, the N/IA ratio was similar between the two soil moisture content treatments but cumulative N 2 O emission was lower at 65% WHC. Conclusions   The effect of soil moisture content on gross nitrification rates differ between forest and grassland soils and decreasing soil moisture content from 100 to 65% WHC reduced N 2 O emissions in both soils. Content Type Journal Article Category Regular Article Pages 1-13 DOI 10.1007/s11104-011-0997-2 Authors Yi Cheng, State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008 China Zu-cong Cai, State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008 China Jin-bo Zhang, State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008 China Man Lang, College of Applied Meteorology, Nanjing University of Information Science & Technology, Nanjing, 210044 China Bruno Mary, INRA, Unit Agro-Impact, Site de Laon, Pole du Griffon, 02000 Barenton-Bugny, France Scott X. Chang, Department of Renewable Resources, University of Alberta, 442 Earth Sciences Building, Edmonton, T6G 2E3 Canada Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Belowground DNA-based techniques: untangling the network of plant root interactions Content Type Journal Article Category Commentary Pages 1-7 DOI 10.1007/s11104-011-0962-0 Authors Liesje Mommer, Nature Conservation and Plant Ecology, Wageningen University, PO Box 47, 6700 AA Wageningen, The Netherlands Alex J. Dumbrell, Department of Biological Sciences, University of Essex, Wivenhoe Park, Colchester, CO4 3SQ UK C. (Niels) A. M. Wagemaker, Molecular Ecology, Institute for Water and Wetland Research, Radboud University Nijmegen, PO Box 9010, 6500 GL Nijmegen, The Netherlands N. Joop Ouborg, Molecular Ecology, Institute for Water and Wetland Research, Radboud University Nijmegen, PO Box 9010, 6500 GL Nijmegen, The Netherlands Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Aims   Iron (Fe) is an essential micronutrient, and plant available Fe is often limited in alkaline soils. Fe deficiency chlorosis decreases plant growth and yield. Identification of germplasm with high and low Fe use efficiency will allow studies to better understand the genetic components for breeding Fe efficient varieties. Methods   A screen using cucumber ( Cucumis sativus ) seedlings identified varieties that maintained contrasting levels of chlorophyll under Fe deficiency or limitation. A time course of mineral dynamics in cotyledons was conducted. Results   The variety Ashley had the highest chlorophyll under Fe deficiency and per unit Fe in the leaf, while the variety Miniature White had the lowest. Ashley also maintained higher chlorophyll when challenged with low Fe or bicarbonate, accumulated greater quantities of Fe, and had higher root ferric reductase activity. Cotyledons accumulated minerals for the first several days, then Fe, P, K, and Cu were remobilized. The Fe use efficient and inefficient varieties remobilized Fe and P on different timescales. Conclusions   Our results suggest that this screen can identify varieties for systems level studies that could elucidate factors needed for Fe use efficiency and remobilization of minerals. The time course indicated that cotyledon Fe stores did not contribute to seedling Fe use efficiency. Content Type Journal Article Category Regular Article Pages 1-13 DOI 10.1007/s11104-011-0988-3 Authors Brian M. Waters, Department of Agronomy and Horticulture, University of Nebraska-Lincoln, Lincoln, NE 68583-0915, USA Grace C. Troupe, Department of Agronomy and Horticulture, University of Nebraska-Lincoln, Lincoln, NE 68583-0915, USA Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Aims   Most cereals accumulate Si in their shoots. Soil bioavailability of Si may be a constraint on the beneficial role of silica in cereals but it is not yet well supported by field data. The aim of this study is to evaluate the long-term impact of wheat straw exports on the pool of soil phytoliths, which, it is suggested, represents the most labile and renewable pool of soil Si. Methods   We measured the amorphous Si (ASi) in soils from several experiments at Rothamsted Research (UK), which provided long-term soil data back to the middle of the 19th century, using two alternative extraction techniques: Na 2 CO 3 (referred to as AS nc ) or zinc bromide extraction (referred to as ASi zb ). Results   All samples showed a similar range of AS nc and ASi zb but low values (0.1–3.4 mg g −1 DW) compared to published data on natural ecosystems. In the Broadbalk experiment, a decrease over time in ASi in the topsoil samples is in good agreement with the hypothesis that cropping and exports of straw leads to depletion of soil phytoliths. A decrease in Si concentration in straw samples was observed between 1883 and 1944. From 1944 to the present, Si concentration increased irregularly in the straw, probably as the result of liming, which enhanced the dissolution of the remaining phytoliths through increasing pH. In the reforested Geescroft field the higher phytolith concentration in the modern topsoil samples is in good agreement with a re-building of phytolith storage from litter input in an acidic environment. Conclusions   Our results therefore support the hypothesis that export of wheat straw leads to a decrease in bioavailable Si. Content Type Journal Article Category Regular Article Pages 1-12 DOI 10.1007/s11104-011-0987-4 Authors Flore Guntzer, CEREGE CNRS/Aix-Marseille Université, Europôle Méditerranéen de l′Arbois, 13545 Aix-en-Provence, cedex 4, France Catherine Keller, CEREGE CNRS/Aix-Marseille Université, Europôle Méditerranéen de l′Arbois, 13545 Aix-en-Provence, cedex 4, France Paul R. Poulton, Rothamsted Research, Harpenden, Herts AL5 2JQ, UK Steve P. McGrath, Rothamsted Research, Harpenden, Herts AL5 2JQ, UK Jean-Dominique Meunier, CEREGE CNRS/Aix-Marseille Université, Europôle Méditerranéen de l′Arbois, 13545 Aix-en-Provence, cedex 4, France Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description:    Deckelnick and Dziuk (Math. Comput. 78(266):645–671, 2009 ) proved a stability bound for a continuous-in-time semidiscrete parametric finite element approximation of the elastic flow of closed curves in \mathbb R d , d ³ 2 . We extend these ideas in considering an alternative finite element approximation of the same flow that retains some of the features of the formulations in Barrett et al. (J Comput Phys 222(1): 441–462, 2007 ; SIAM J Sci Comput 31(1):225–253, 2008 ; IMA J Numer Anal 30(1):4–60, 2010 ), in particular an equidistribution mesh property. For this new approximation, we obtain also a stability bound for a continuous-in-time semidiscrete scheme. Apart from the isotropic situation, we also consider the case of an anisotropic elastic energy. In addition to the evolution of closed curves, we also consider the isotropic and anisotropic elastic flow of a single open curve in the plane and in higher codimension that satisfies various boundary conditions. Content Type Journal Article Pages 1-54 DOI 10.1007/s00211-011-0416-x Authors John W. Barrett, Department of Mathematics, Imperial College London, London, SW7 2AZ UK Harald Garcke, Fakultät für Mathematik, Universität Regensburg, 93040 Regensburg, Germany Robert Nürnberg, Department of Mathematics, Imperial College London, London, SW7 2AZ UK Journal Numerische Mathematik Online ISSN 0945-3245 Print ISSN 0029-599X

Description: Background and aims   Characterisation of genetic variation in nitrate accumulation by lettuce will inform strategies for selecting low-nitrate varieties more capable of meeting EU legislation on harvested produce. This study uses a population of recombinant inbred lines (RILs) of lettuce to determine how genotypic differences influence N uptake, N assimilation and iso-osmotic regulation, and to identify key related traits prior to future genetic analysis. Methods   Measurements were made on plants grown to maturity in soil fertilised with ammonium nitrate, and in a complete nutrient solution containing only nitrate-N. A simple osmotic balance model was developed to estimate variations in shoot osmotic concentration between RILs. Results   There were significant genotypic variations in nitrate accumulation when plants were grown either with nitrate alone or in combination with ammonium. Ammonium-N significantly reduced nitrate in the shoot but had no effect on its relative variability, or on the ranking of genotypes. Shoot nitrate-N was correlated positively with total-N and tissue water, and negatively with assimilated-C in both experiments. Corresponding relationships with assimilated-N and shoot weight were weaker. Estimated concentrations of total osmotica in shoot sap were statistically identical in all RILs, despite variations in nitrate concentration across the population. Conclusions   Approximately 73% of the genotypic variability in nitrate accumulation within the population of RILs arose from differences in nitrate uptake and only 27% from differences in nitrate assimilated, irrespective of whether or not part of the N was recovered as ammonium, or whether the plants were grown in soil or solution culture. Genotypic variability in nitrate accumulation was associated with changes in concentrations of other endogenous solutes (especially carboxylates and soluble carbohydrates) and of tissue water, which minimised differences in osmotic potential of shoot sap between RILs. This offers the opportunity of using the regulation of these solutes as additional traits to manipulate nitrate accumulation. Content Type Journal Article Category Regular Article Pages 1-19 DOI 10.1007/s11104-011-0999-0 Authors Ian G. Burns, Warwick Crop Centre, School of Life Sciences, Wellesbourne Campus, University of Warwick, Wellesbourne, Warwick, CV35 9EF UK James Durnford, Warwick Crop Centre, School of Life Sciences, Wellesbourne Campus, University of Warwick, Wellesbourne, Warwick, CV35 9EF UK James Lynn, Applied Statistical Solutions, 10 Church Hill, Bishops Tachbrook, Warwickshire, CV33 9RJ UK Sandy McClement, Warwick Crop Centre, School of Life Sciences, Wellesbourne Campus, University of Warwick, Wellesbourne, Warwick, CV35 9EF UK Paul Hand, Harper Adams University College, Newport, Shropshire TF10 8NB, UK David Pink, Harper Adams University College, Newport, Shropshire TF10 8NB, UK Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Background and aims   Many plant-beneficial microorganisms can influence secondary plant metabolism, but whether these effects add up when plants are co-inoculated is unclear. This issue was assessed, under field conditions, by comparing the early impacts of seed inoculation on secondary metabolite profiles of maize at current or reduced mineral fertilization levels. Methods   Maize seeds were inoculated singly with selected strains from bacterial genera Pseudomonas and Azospirillum or mycorrhizal genus Glomus , or with these strains combined two by two or all three together. At 16 days, maize root methanolic extracts were analyzed by RP-HPLC and secondary metabolites (phenolics, flavonoids, xanthones, benzoxazionoids, etc.) identified by LC/MS. Results   Inoculation did not impact on plant biomass but resulted in enhanced total root surface, total root volume and/or root number in certain inoculated treatments, at reduced fertilization. Inoculation led to qualitative and quantitative modifications of root secondary metabolites, particularly benzoxazinoids and diethylphthalate. These modifications depended on fertilization level and microorganism(s) inoculated. The three selected strains gave distinct results when used alone, but unexpectedly all microbial consortia gave somewhat similar results. Conclusions   The early effects on maize secondary metabolism were not additive, as combining strains gave effects similar to those of Glomus alone. This is the first study demonstrating and analyzing inoculation effects on crop secondary metabolites in the field. Content Type Journal Article Category Regular Article Pages 1-13 DOI 10.1007/s11104-011-0960-2 Authors Vincent Walker, Université de Lyon, 69622 Lyon, France Olivier Couillerot, Université de Lyon, 69622 Lyon, France Andreas Von Felten, Institute of Integrative Biology, ETH, CH-8092 Zürich, Switzerland Floriant Bellvert, Université de Lyon, 69622 Lyon, France Jan Jansa, Institute of Plant Agricultural Sciences, ETH, Eschikon 33, CH-8315 Lindau, Switzerland Monika Maurhofer, Institute of Integrative Biology, ETH, CH-8092 Zürich, Switzerland René Bally, Université de Lyon, 69622 Lyon, France Yvan Moënne-Loccoz, Université de Lyon, 69622 Lyon, France Gilles Comte, Université de Lyon, 69622 Lyon, France Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Soil-plant-microbe interactions from microscopy to field practice Content Type Journal Article Category Editorial Pages 1-5 DOI 10.1007/s11104-011-0969-6 Authors Lynette K. Abbott, School of Earth and Environment, The UWA institute of Agriculture, Faculty of Natural and Agricultural Sciences, The University of Western Australia, Crawley, WA 6009, Australia Caixian Tang, Department of Agriculture Science/Centre for AgriBioscience, La Trobe University, Melbourne Campus, Bundoora, VIC 3086, Australia Doug Reuter, Reuter and Associates, Medindie, SA 5081, Australia Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description: Aims   Higher plants are an understudied component of the global silicon cycle; they absorb silicic acid (dSi) which is stored as biogenic silica (bSiO 2 ). Si is believed to alleviate physical, chemical, and biological stresses such as storms, high salinity, heavy metal toxicity, grazing, and disease. We investigated a Si-accumulating invasive species growing in the tidal marshes of the Bay of Brest (France), viz., Spartina alterniflora . Our objectives were to determine (1) where and when bSiO 2 accumulates in the plant during its life cycle, (2) whether this accumulation varies with abiotic factors: wave action, estuarine salinity, and duration of immersion, and (3) if the accumulation was limited by dSi availability in marsh porewater. Methods   A 2 years field survey permitted to sample plants which were analyzed for there bSiO 2 concentrations. Sediment cores were sampled seasonally and the dSi concentrations in the porewater were measured from 0 to 10 cm. Results   bSiO 2 accumulated more in mature leaves than in other organs. There was a strong linear relationship between bSiO 2 concentration and plant length. bSiO 2 concentrations did not increase, but rather decreased as a function of exposure to the three abiotic factors tested. dSi availability was not significantly different for each of the tested sites and dSi profiles did not exhibit huge losses in the root zone. Conclusions   Our evidence suggests that dSi availability did not seem to be a limiting factor. bSiO 2 did not increase with increasing abiotic stresses but was strongly correlated with growth. Hence, S. alterniflora is likely to have other adaptive strategies for dealing with environmental stressors but it did not exclude the possible role of Si in alleviating these stresses. If this is the case, there remain intriguing questions about Si uptake, its availability, and its role in silicification and growth. Content Type Journal Article Category Regular Article Pages 1-15 DOI 10.1007/s11104-011-0986-5 Authors Jérémy Querné, LEMAR UMR6539, U.B.O, Institut Universitaire Européen de la Mer, I.U.E.M, Université de Bretagne Occidentale, place Nicolas Copernic, 29280 Plouzane, France Olivier Ragueneau, LEMAR UMR6539, U.B.O, Institut Universitaire Européen de la Mer, I.U.E.M, Université de Bretagne Occidentale, place Nicolas Copernic, 29280 Plouzane, France Nathalie Poupart, LEBHAM EA3877, U.B.O, Institut Universitaire Européen de la Mer, I.U.E.M, Université de Bretagne Occidentale, place Nicolas Copernic, 29280 Plouzane, France Journal Plant and Soil Online ISSN 1573-5036 Print ISSN 0032-079X

Description:    We consider convergence analysis for a model reduction algorithm for a class of linear infinite dimensional systems. The algorithm computes an approximate balanced truncation of the system using solution snapshots of specific linear infinite dimensional differential equations. The algorithm is related to the proper orthogonal decomposition, and it was first proposed for systems of ordinary differential equations by Rowley (Int. J. Bifurc. Chaos Appl. Sci. Eng. 15(3):997–1013, 2005 ). For the convergence analysis, we consider the algorithm in terms of the Hankel operator of the system, rather than the product of the system Gramians as originally proposed by Rowley. For exponentially stable systems with bounded finite rank input and output operators, we prove that the balanced realization can be expressed in terms of balancing modes, which are related to the Hankel operator. The balancing modes are required to be smooth, and this can cause computational difficulties for PDE systems. We show how this smoothness requirement can be lessened for parabolic systems, and we also propose a variation of the algorithm that avoids the smoothness requirement for general systems. We prove entrywise convergence of the matrices in the approximate reduced order models in both cases, and present numerical results for two example PDE systems. Content Type Journal Article Pages 1-38 DOI 10.1007/s00211-011-0424-x Authors John R. Singler, Department of Mathematics and Statistics, Missouri University of Science and Technology, Rolla, MO 65409-0020, USA Journal Numerische Mathematik Online ISSN 0945-3245 Print ISSN 0029-599X

Description:    We present and analyze subspace correction methods for the solution of variational inequalities of the second kind and apply these theoretical results to non smooth contact problems in linear elasticity with Tresca and non-local Coulomb friction. We introduce these methods in a reflexive Banach space, prove that they are globally convergent and give error estimates. In the context of finite element discretizations, where our methods turn out to be one- and two-level Schwarz methods, we specify their convergence rate and its dependence on the discretization parameters and conclude that our methods converge optimally. Transferring this results to frictional contact problems, we thus can overcome the mesh dependence of some fixed-point schemes which are commonly employed for contact problems with Coulomb friction. Content Type Journal Article Pages 1-27 DOI 10.1007/s00211-011-0423-y Authors L. Badea, Institute of Mathematics of the Romanian Academy, P.O. Box 1-764, 014700 Bucharest, Romania R. Krause, Institute of Computational Science, University of Lugano, via Giuseppe Buffi 13, 6900 Lugano, Switzerland Journal Numerische Mathematik Online ISSN 0945-3245 Print ISSN 0029-599X

Description:    We discuss the full discretization of an elliptic optimal control problem with pointwise control and state constraints. We provide the first reliable a-posteriori error estimator that contains only computable quantities for this class of problems. Moreover, we show, that the error estimator converges to zero if one has convergence of the discrete solutions to the solution of the original problem. The theory is illustrated by numerical tests. Content Type Journal Article Pages 1-30 DOI 10.1007/s00211-011-0422-z Authors Arnd Rösch, Fakultät für Mathematik, Universität Duisburg-Essen, Forsthausweg 2, 47057 Duisburg, Germany Daniel Wachsmuth, Johann Radon Institute for Computational and Applied Mathematics (RICAM), Austrian Academy of Sciences, Altenbergerstraße 69, 4040 Linz, Austria Journal Numerische Mathematik Online ISSN 0945-3245 Print ISSN 0029-599X

Description:    Invariant pairs have been proposed as a numerically robust means to represent and compute several eigenvalues along with the corresponding (generalized) eigenvectors for matrix eigenvalue problems that are nonlinear in the eigenvalue parameter. In this work, we consider nonlinear eigenvalue problems that depend on an additional parameter and our interest is to track several eigenvalues as this parameter varies. Based on the concept of invariant pairs, a theoretically sound and reliable numerical continuation procedure is developed. Particular attention is paid to the situation when the procedure approaches a singularity, that is, when eigenvalues included in the invariant pair collide with other eigenvalues. For the real generic case, it is proven that such a singularity only occurs when two eigenvalues collide on the real axis. It is shown how this situation can be handled numerically by an appropriate expansion of the invariant pair. The viability of our continuation procedure is illustrated by a numerical example. Content Type Journal Article Pages 1-28 DOI 10.1007/s00211-011-0392-1 Authors Wolf-Jürgen Beyn, Fakultät für Mathematik, Universität Bielefeld, Postfach 100131, 33501 Bielefeld, Germany Cedric Effenberger, Seminar for Applied Mathematics, D-MATH, ETH Zurich, Raemistrasse 101, 8092 Zurich, Switzerland Daniel Kressner, MATHICSE, EPF Lausanne, Station 8, 1015 Lausanne, Switzerland Journal Numerische Mathematik Online ISSN 0945-3245 Print ISSN 0029-599X