ALBERT

Beschreibung: Agronomy, Vol. 7, Pages 54: Combination of Lactic Acid-Based Deep Eutectic Solvents (DES) with β-Cyclodextrin: Performance Screening Using Ultrasound-Assisted Extraction of Polyphenols from Selected Native Greek Medicinal Plants Agronomy doi: 10.3390/agronomy7030054 Authors: Chrysa Georgantzi Antonia-Eleni Lioliou Nikos Paterakis Dimitris Makris A series of novel l-lactic acid-based deep eutectic solvents (DES) were tested for polyphenol extraction performance, using organically grown, native Greek medicinal plants. The extractions were ultrasonically-assisted and the effect of the addition of β-cyclodextrin (β-CD) as extraction booster was also tested, at a concentration of 1.5% (w/v). The estimation of total polyphenol yield (YTP) suggested that DES composed of l-lactic acid and nicotinamide and l-lactic acid and l-alanine, both at a molar ratio of 7:1, are promising solvents giving significantly higher yields compared with 60% (v/v) aqueous ethanol and water. However, when β-CD was combined with DES comprised of l-lactic acid and ammonium acetate (molar ratio 7:1), the extraction yields obtained in some instances were equal of even higher. The pattern was not consistent when the yield in total flavonoids (YTFn) was considered, indicating water, 60% (v/v) aqueous ethanol and l-lactic acid:sodium acetate (molar ratio 7:1) to be the most efficient solvents. In this case, the effect of β-CD was of rather lower magnitude. The examination of the antioxidant activity of the extracts generated showed that there is a close correlation mainly with their concentration in total polyphenols.

Beschreibung: Agronomy, Vol. 7, Pages 55: Impacts of Fertilization Type on Soil Microbial Biomass and Nutrient Availability in Two Agroecological Zones of Ghana Agronomy doi: 10.3390/agronomy7030055 Authors: Richard Omari Elsie Sarkodee-Addo Yoshiharu Fujii Yosei Oikawa Sonoko Bellingrath-Kimura The decline in soil productivity amidst efforts to increase crop yield in Sub Saharan Africa (SSA) has made it imperative to assess the current fertilization management approaches. This study was conducted in two agroecological zones (i.e., Guinea Savannah (GS) and Deciduous forest (DF)) of Ghana to evaluate how different fertilization schemes in the long term (>5 years) impacted the soil biochemical properties. Soil samples under four fertilization schemes (inorganic fertilizer only, low-to-medium organic residues only, inorganic fertilizers plus low-to-medium organic residues, and no fertilization) from 20 farmers’ field were sampled from March to April 2015. Soil biochemical quality indicators were determined using standard procedures. Overall, the average chemical and microbial biomass contents for most indicators were significantly higher in DF compared to GS. Relative to the reference sites, soil quality improvement were observed under inorganic fertilization in both agroecologies in contrast to significant soil deterioration (26.5%) under sole organic residue application in GS. Furthermore, the results showed that increased inorganic fertilization rate alone or combination with organic residues improved soil quality relative to the reference. The present results suggest the need to raise the current fertilizer application rates, especially in GS in order to enhance optimum soil productivity.

Beschreibung: Agronomy, Vol. 7, Pages 57: Responses of Fourteen Vietnamese Rice (Oryza sativa L.) Cultivars to High Temperatures during Grain Filling Period under Field Conditions Agronomy doi: 10.3390/agronomy7030057 Authors: Tran Thuy Kuniyiki Saitoh High temperatures significantly affect rice grain yield and quality. However, little information is known about the response of indica cultivars, especially Vietnamese cultivars, to high temperature. In this study, field experiments were conducted in 2015 and 2016 to evaluate the response of Vietnamese cultivars under high temperatures during the grain filling period. The high temperature was applied after the first cultivar started anthesis, by opening two sides of a plastic chamber that housed the cultivar when the temperature reached above 36 °C under field conditions. The difference in the maximum temperature between the control and the high temperature treatment was about 1.3 °C to 10.1 °C in 2015, and 0.73 °C to 10.2 °C in 2016. Decreases in crop growth rate (CGR) and yield were correlated with increased temperature conditions during the grain filling period. The grain yield of 14 Vietnamese cultivars fell to 81.5 and 79.4% of the control in 2015 and 2016, respectively. The variable with the greatest impact on grain yield was spikelet sterility induced by high temperature. Under high temperature conditions during the grain filling period, the percentage of grain chalkiness in the high temperature-treatment group increased compared to the control. Our study showed that Vietnamese rice yield and quality were significantly affected by high temperature.

Beschreibung: Agronomy, Vol. 7, Pages 59: Farming in Northern Ontario: Untapped Potential for the Future Agronomy doi: 10.3390/agronomy7030059 Authors: Tejendra Chapagain Farming in Northern Ontario is limited to less than 1% of the total land area available. With over 2000 farms, this is home to about 6% of the province’s population, concentrated in the five major southern border cities of Thunder Bay, Sault Ste. Marie, Timmins, Sudbury and North Bay, with a significant presence of indigenous (i.e., First Nations) and disadvantaged peoples. This review highlights the challenges and opportunities of agriculture in Northern Ontario and offers a few strategies for establishing and sustaining agricultural operations locally. The challenges of farming in this region include the prevalence of adverse climatic conditions, lack of crop/economic diversification, insufficient infrastructure and support services, presence of small local markets, an aging population and youth out-migration, attitudes of dependency on government and limited investment potential. Nevertheless, this region offers much potential for farming as it contains significant amounts of fertile soils, good road networks and affordable land to start up farm businesses. Furthermore, the changing climate could be a boon to improve growing conditions, with expanded cropping options and increased yields in recent years. Production and consumption of local foods, conducting innovative on-farm research that addresses the needs of local producers including First Nations peoples, fostering regional research centres, building relationships through networking, exchange of ideas through effective use of different extension avenues, and collaboration and assisting local producers with market development may help establish a more competitive and sustainable agrifood sector in Northern Ontario. Favourable government policies to support growers who have experienced damage to their crops, forages and livestock due to adverse climatic conditions will further help sustain and expand their agricultural operations.

Beschreibung: Agronomy, Vol. 7, Pages 60: Glyphosate Efficacy of Different Salt Formulations and Adjuvant Additives on Various Weeds Agronomy doi: 10.3390/agronomy7030060 Authors: Ilias Travlos Nikolina Cheimona Dimitrios Bilalis In many crops, weeds are managed by herbicides, mainly due to the decrease in crop yields and farmers’ incomes caused by them. In general, chemical control of weeds is considered to be an easy, relatively cheap, and highly effective method. However, not all weeds can be successfully controlled, either because of their natural tolerance or their herbicide resistance. Glyphosate is one of the most widely used herbicides in the world. It can manage effectively a broad spectrum of weeds, and promotes conservation agriculture by significantly reducing conventional plough tillage. Unfortunately, its extensive use has led to the evolution of glyphosate resistance, which has evolved into a major problem for global crop production. Alternative herbicides are, in some cases, available, but they do not usually control certain weeds as efficiently as glyphosate. The transmission of herbicides to the target site is a complex process, and consists of several stages. Each herbicide is affected and can be manipulated by the product formulation for the optimization of its use. Many experiments have confirmed that different glyphosate salts and adjuvant additives are instrumental in the optimization of herbicide absorption and delivery processes. The objective of this paper is to provide a brief overview of these experiments and summarize the literature related to the effect of various glyphosate formulations and adjuvants on weed control. Determining the differences among formulations and adjuvants may lead to the further optimized long-term use of glyphosate.

Beschreibung: Agronomy, Vol. 7, Pages 56: Understanding Starch Structure: Recent Progress Agronomy doi: 10.3390/agronomy7030056 Authors: Eric Bertoft Starch is a major food supply for humanity. It is produced in seeds, rhizomes, roots and tubers in the form of semi-crystalline granules with unique properties for each plant. Though the size and morphology of the granules is specific for each plant species, their internal structures have remarkably similar architecture, consisting of growth rings, blocklets, and crystalline and amorphous lamellae. The basic components of starch granules are two polyglucans, namely amylose and amylopectin. The molecular structure of amylose is comparatively simple as it consists of glucose residues connected through α-(1,4)-linkages to long chains with a few α-(1,6)-branches. Amylopectin, which is the major component, has the same basic structure, but it has considerably shorter chains and a lot of α-(1,6)-branches. This results in a very complex, three-dimensional structure, the nature of which remains uncertain. Several models of the amylopectin structure have been suggested through the years, and in this review two models are described, namely the “cluster model” and the “building block backbone model”. The structure of the starch granules is discussed in light of both models.

Beschreibung: Agronomy, Vol. 7, Pages 58: Volatile Semiochemical Mediated Plant Defense in Cereals: A Novel Strategy for Crop Protection Agronomy doi: 10.3390/agronomy7030058 Authors: Amanuel Tamiru Zeyaur Khan Plants have evolved highly intriguing ways of defending themselves against insect attacks, including through emission of defense volatiles. These volatiles serve the plant’s defense by directly repelling phytophagous insects and/or indirectly through attracting natural enemies antagonistic to the herbivores. Several laboratory studies established the potential of improving plant resistance against insect attacks by manipulating the plant-derived volatile semiochemicals emissions. Yet, more efforts need to be conducted to translate the promising laboratory studies to fight economically-important crop pests under real field conditions. This is needed to address an increasing demand for alternative pest control options driven by ecological and environmental costs associated with the use of broad-spectrum insecticides. The practical examples discussed in this review paper demonstrate the real prospect of exploiting an inducible and constitutive plant volatile semiochemicals for developing novel and ecologically-sustainable pest management strategies to protect cereal crops from damaging insect pests.

Beschreibung: Agronomy, Vol. 7, Pages 62: Geographic and Research Center Origins of Rice Resistance to Asian Planthoppers and Leafhoppers: Implications for Rice Breeding and Gene Deployment Agronomy doi: 10.3390/agronomy7040062 Authors: Finbarr Horgan Thanga Srinivasan Jagadish Bentur Ram Kumar K. Bhanu Preetinder Sarao Ho Chien Maria Almazan Carmencita Bernal Angelee Ramal Jedeliza Ferrater Shou-Horng Huang This study examines aspects of virulence to resistant rice varieties among planthoppers and leafhoppers. Using a series of resistant varieties, brown planthopper, Nilaparvata lugens, virulence was assessed in seedlings and early-tillering plants at seven research centers in South and East Asia. Virulence of the whitebacked planthopper, Sogatella furcifera, in Taiwan and the Philippines was also assessed. Phylogenetic analysis of the varieties using single-nucleotide polymorphisms (SNPs) indicated a clade of highly resistant varieties from South Asia with two further South Asian clades of moderate resistance. Greenhouse bioassays indicated that planthoppers can develop virulence against multiple resistance genes including genes introgressed from wild rice species. Nilaparvata lugens populations from Punjab (India) and the Mekong Delta (Vietnam) were highly virulent to a range of key resistance donors irrespective of variety origin. Sogatella furcifera populations were less virulent to donors than N. lugens; however, several genes for resistance to S. furcifera are now ineffective in East Asia. A clade of International Rice Research Institute (IRRI)-bred varieties and breeding lines, without identified leafhopper-resistance genes, were highly resistant to the green leafhopper, Nephotettix virescens. Routine phenotyping during breeding programs likely maintains high levels of quantitative resistance to leafhoppers. We discuss these results in the light of breeding and deploying resistant rice in Asia.

Beschreibung: Agronomy, Vol. 7, Pages 65: Effect of Vegetative Propagation Materials on Globe Artichoke Production in Semi-Arid Developing Countries: Agronomic, Marketable and Qualitative Traits Agronomy doi: 10.3390/agronomy7040065 Authors: Jouhaina Riahi Carlo Nicoletto Ghaith Bouzaein Paolo Sambo Karima Khalfallah In Tunisia, globe artichoke is mainly propagated by underground dormant axillary buds (ovoli), which are removed from the field in August during the quiescence period. The high cost of in vitro-plants and the absence of specialized nurseries were among the reasons for the rise of heterogeneity and spread of diseases. The aim was to help farmers to improve artichoke yield and quality by ameliorating their vegetative propagation technique with low cost methods. Three plant cuttings management methods were tested: summer ovoli (T0); spring offshoots nursery’s cuttings forced to pass a vegetative rest period by stopping irrigation (T1); and offshoots nursery’s cuttings not forced (T2). The cuttings management can affect both yield and qualitative traits of artichoke. T1 nursery plants produced the heaviest primary heads, 7% and 23% higher than T2 and T0, respectively. T1 plants exhibited the highest yield during the harvest season, with +17.7% and +12.2% compared to T0 and T2, respectively. T0 and T1 showed the highest total antioxidant capacity and inulin content; the propagation method also affected the short-chain sugars ratio. T1 is a viable and sustainable alternative to the traditional one that does not heavily impact on growing costs and improves yield and quality of artichoke.

Beschreibung: Agronomy, Vol. 7, Pages 63: Vegetable Intercropping in a Small-Scale Aquaponic System Agronomy doi: 10.3390/agronomy7040063 Authors: Carmelo Maucieri Carlo Nicoletto Zala Schmautz Paolo Sambo Tamas Komives Maurizio Borin Ranka Junge This paper reports the results of the first study of an aquaponic system for Pangasianodon hypophthalmus production that uses Lactuca sativa L. (lettuce) and Cichorium intybus L. rubifolium group (red chicory) intercropping in the hydroponic section. The experiment was conducted in a greenhouse at the Zurich University of Applied Sciences, Wädenswil, Switzerland, using nine small-scale aquaponic systems (each approximately 400 L), with the nutrient film technique (NFT). The intercropping of vegetables did not influence the water temperature, pH, electric conductivity (EC), oxidation–reduction potential, nor O2 content. Intercropping with red chicory increased the lettuce sugar content (+16.0% and +25.3% for glucose and fructose, respectively) and reduced the lettuce caffeic acid content (−16.8%). In regards to bitter taste compounds (sesquiterpene lactones), intercropping reduced the concentrations of dihydro-lactucopicrin + lactucopicrin (−42.0%) in lettuce, and dihydro-lactucopicrin + lactucopicrin (−22.0%) and 8-deoxy–lactucin + dihydro-lactucopicrin oxalate (−18.7%) in red chicory, whereas dihydro-lactucin content increased (+40.6%) in red chicory in regards to monoculture. A significantly higher organic nitrogen content was found in the lettuce (3.9%) than in the red chicory biomass (3.4%), following the intercropping treatment. Anion and cation contents in vegetables were affected by species (Cl−, NO3−, PO43−, SO42−, and Ca2+), intercropping (K+ and Mg2+), and species × intercropping interactions (NO2− and NH4+). Experimental treatments (monoculture vs intercropping and distance from NFT inlet) did not exert significant effects on leaf SPAD (index of relative chlorophyll content) values, whereas the red coloration of the plants increased from the inlet to the outlet of the NFT channel. Intercropping of lettuce and red chicory affected the typical taste of these vegetables by increasing the sweetness of lettuce and changing the ratio among bitter taste compounds in red chicory. These results suggest intercropping as a possible solution for improving vegetable quality in aquaponics. Although the results are interesting, they have been obtained in a relatively short period, thus investigations for longer periods are necessary to confirm these findings. Further studies are also needed to corroborate the positive effect of the presence of red chicory in the system on fish production parameters.

Beschreibung: Agronomy, Vol. 7, Pages 64: Evaluating Agricultural Management Effects on Alachlor Availability: Tillage, Green Manure, and Biochar Agronomy doi: 10.3390/agronomy7040064 Authors: Kassio Mendes Kathleen Hall Kurt Spokas William Koskinen Valdemar Tornisielo Agricultural and soil management practices have been reported to affect alachlor sorption–desorption and degradation rates. Though alachlor has been banned in the E.U. since 2006, it is still used in U.S. corn and soybean production. The objectives of this study were to: (a) assess differences in alachlor sorption due to tillage treatments (chisel plow and ridge tillage) on soils from three midwestern U.S. locations; and (b) determine the effect of various soil amendments on the sorption–desorption and mineralization of alachlor. Soils were amended at a rate of 10% (w/w) with biochars derived from soybean stover, sugarcane bagasse, and wood chips, as well as the uncharred feedstock materials. Sorption–desorption studies were performed using the batch equilibration method, and alachlor mineralization was evaluated in a 30-day incubation. Tillage management did not affect alachlor sorption to soil across the three sites, despite the fact that the tillage operations were imposed for 4 years (p > 0.05). While the sorption coefficient (Kd) values for alachlor were relatively low in the three unamended soils (Kd = 1.76, 1.73, and 1.15 L·kg−1 for IL, MN, and PA soils, respectively), biochar amendments increased alachlor sorption between 4× and 33× compared to the unamended soil. The amendments also affected alachlor mineralization such that degradation was slower in both biochar- and raw feedstock-amended soils. Based on these results, biochar additions are expected to affect the availability of alachlor for transport and degradation. Furthermore, this study highlights the larger impact of biochar addition than tillage practices on altering immediate alachlor sorption capacities.

Beschreibung: Agronomy, Vol. 7, Pages 61: Response of Chlorophyll, Carotenoid and SPAD-502 Measurement to Salinity and Nutrient Stress in Wheat (Triticum aestivum L.) Agronomy doi: 10.3390/agronomy7030061 Authors: Syed Shah Rasmus Houborg Matthew McCabe Abiotic stress can alter key physiological constituents and functions in green plants. Improving the capacity to monitor this response in a non-destructive manner is of considerable interest, as it would offer a direct means of initiating timely corrective action. Given the vital role that plant pigments play in the photosynthetic process and general plant physiological condition, their accurate estimation would provide a means to monitor plant health and indirectly determine stress response. The aim of this work is to evaluate the response of leaf chlorophyll and carotenoid (Ct) content in wheat (Triticum aestivum L.) to changes in varying application levels of soil salinity and fertilizer applied over a complete growth cycle. The study also seeks to establish and analyze relationships between measurements from a SPAD-502 instrument and the leaf pigments, as extracted at the anthesis stage. A greenhouse pot experiment was conducted in triplicate by employing distinct treatments of both soil salinity and fertilizer dose at three levels. Results showed that higher doses of fertilizer increased the content of leaf pigments across all levels of soil salinity. Likewise, increasing the level of soil salinity significantly increased the chlorophyll and Ct content per leaf area at all levels of applied fertilizer. However, as an adaptation process and defense mechanism under salinity stress, leaves were found to be thicker and narrower. Thus, on a per-plant basis, increasing salinity significantly reduced the chlorophyll (Chlt) and Ct produced under each fertilizer treatment. In addition, interaction effects of soil salinity and fertilizer application on the photosynthetic pigment content were found to be significant, as the higher amounts of fertilizer augmented the detrimental effects of salinity. A strong positive (R2 = 0.93) and statistically significant (p < 0.001) relationship between SPAD-502 values and Chlt and between SPAD-502 values and Ct content (R2 = 0.85) was determined based on a large (n = 277) dataset. We demonstrate that the SPAD-502 readings and plant photosynthetic pigment content per-leaf area are profoundly affected by salinity and nutrient stress, but that the general form of their relationship remains largely unaffected by the stress. As such, a generalized regression model can be used for Chlt and Ct estimation, even across a range of salinity and fertilizer gradients.

Beschreibung: Flowering time is a key target trait for extending the vegetative phase to increase biomass in bioenergy crops such as perennial C4 grasses. Molecular genetic studies allow the identification of genes involved in the control of flowering in different species. Some regulatory factors of the Arabidopsis pathway are conserved in other plant species such as grasses. However, differences in the function of particular genes confer specific responses to flowering. One of the major pathways is photoperiod regulation, based on the interaction of the circadian clock and environmental light signals. Depending on their requirements for day-length plants can be classified as long-day (LD), short-day (SD), and day-neutral. The CONSTANS (CO) and Heading Date 1 (Hd1), orthologos genes, are central regulators in the flowering of Arabidopsis and rice, LD and SD plants, respectively. Additionally, Early heading date 1 (Ehd1) induces the expression of Heading date 3a (Hd3a), conferring SD promotion and controls Rice Flowering Locus T 1 (RFT1) in LD conditions, independently of Hd1. Nevertheless, the mechanisms promoting flowering in perennial bioenergy crops are poorly understood. Recent progress on the regulatory network of important gramineous crops and components involved in flowering control will be discussed.

Beschreibung: Seasonal growth patterns of perennial plants are linked to patterns of acclimation and de-acclimation to seasonal stresses. The timing of cold acclimation (development of freezing resistance) and leaf growth cessation in autumn, and the timing of de-acclimation and leaf regrowth in spring, is regulated by seasonal cues in the environment, mainly temperature and light factors. Warming will lead to new combinations of these cues in autumn and spring. Extended thermal growing seasons offer a possibility for obtaining increased yields of perennial grasses at high latitudes. Increased productivity in the autumn may not be possible in all high latitude regions due to the need for light during cold acclimation and the need for accumulating a carbohydrate storage prior to winter. There is more potential for increased yields in spring due to the availability of light, but higher probability of freezing events in earlier springs would necessitate a delay of de-acclimation, or an ability to rapidly re-acclimate. In order to optimize the balance between productivity and overwintering in the future, the regulation of growth and acclimation processes may have to be modified. Here, the current knowledge on the coordinated regulation of growth and freezing resistance in perennial grasses is reviewed.

Beschreibung: This review deals with the adaptive mechanisms that plants can implement to cope with the challenge of salt stress. Plants tolerant to NaCl implement a series of adaptations to acclimate to salinity, including morphological, physiological and biochemical changes. These changes include increases in the root/canopy ratio and in the chlorophyll content in addition to changes in the leaf anatomy that ultimately lead to preventing leaf ion toxicity, thus maintaining the water status in order to limit water loss and protect the photosynthesis process. Furthermore, we deal with the effect of salt stress on photosynthesis and chlorophyll fluorescence and some of the mechanisms thought to protect the photosynthetic machinery, including the xanthophyll cycle, photorespiration pathway, and water-water cycle. Finally, we also provide an updated discussion on salt-induced oxidative stress at the subcellular level and its effect on the antioxidant machinery in both salt-tolerant and salt-sensitive plants. The aim is to extend our understanding of how salinity may affect the physiological characteristics of plants.

Beschreibung: Conservation agriculture is often presented as being ‘climate smart’ due to anticipated increases in soil moisture. The extent of enhanced water availability in farmers’ fields is, however, poorly documented. This paper presents five data sets describing soil moisture in fields of small-scale conservation and conventional farmers in the Agro-ecological Zone IIa, Zambia. The data include (1) soil cover; (2) time required for visible soil surface saturation, ponding and initial runoff under artificial rainfall; (3) saturated water infiltration rates; (4) weekly soil moisture at six soil depths for two entire rain seasons; and (5) weekly rainfall in each field. Measurements were done for 15 pairs of comparable fields under conservation and conventional agriculture. Pairwise analysis showed significantly shorter time for surface saturation, ponding, and runoff in conservation fields compared to conventional fields. Saturated infiltration rates in riplines and basins of conservation fields were similar to rates in ploughed/hoed fields. Infiltration rates between riplines and between basins were 31–37% lower than those in ploughed/hoed fields. Soil moisture in riplines and basins of conservation fields was higher by an average factor of 1.08 down to 40 cm soil depth, whereas it was lower by an average factor of 0.89 between plant rows compared to fields under conventional tillage. Based on 34,000 soil moisture measurements from 0 to 60 cm depth over two seasons, soils in conservation fields contained a weighted average of 18.2% (vol.) water compared to 19.9% (vol.) in conventional fields (p 〈 0.05). The results indicate that small-scale adopters of conservation agriculture are less ‘climate smart’ than conventional farmers in terms of water infiltration and soil moisture.

Beschreibung: After uptake in cereal crops, nitrogen (N) is rapidly assimilated into glutamine (Gln) and other amino acids for transport to sinks. Therefore Gln has potential as an improved indicator of soil N availability compared to plant N demand. Gln has primarily been assayed to understand basic plant physiology, rather than to measure plant/soil-N under field conditions. It was hypothesized that leaf Gln at early-to-mid season could report the N application rate and predict end-season grain yield in field-grown maize. A three-year maize field experiment was conducted with N application rates ranging from 30 to 218 kg ha−1. Relative leaf Gln was assayed from leaf disk tissue using a whole-cell biosensor for Gln (GlnLux) at the V3-V14 growth stages. SPAD (Soil Plant Analysis Development) and NDVI (Normalized Difference Vegetation Index) measurements were also performed. When sampled at V6 or later, GlnLux glutamine output consistently correlated with the N application rate, end-season yield, and grain N content. Yield correlation outperformed GreenSeekerTM NDVI, and was equivalent to SPAD chlorophyll, indicating the potential for yield prediction. Additionally, depleting soil N via overplanting increased GlnLux resolution to the earlier V5 stage. The results of the study are discussed in the context of luxury N consumption, leaf N remobilization, senescence, and grain fill. The potential and challenges of leaf Gln and GlnLux for the study of crop N physiology, and future N management are also discussed.

Beschreibung: Previous studies conducted on a unique field site comprising three contrasting soils (diluvial sand DS, alluvial loam AL, loess loam LL) under identical cropping history, demonstrated soil type-dependent differences in biocontrol efficiency against Rhizoctonia solani-induced bottom rot disease in lettuce by two bacterial inoculants (Pseudomonas jessenii RU47 and Serratia plymuthica 3Re-4-18). Disease severity declined in the order DS > AL > LL. These differences were confirmed under controlled conditions, using the same soils in minirhizotron experiments. Gas chromatography-mass spectrometry (GC-MS) profiling of rhizosphere soil solutions revealed benzoic and lauric acids as antifungal compounds; previously identified in root exudates of lettuce. Pathogen inoculation and pre-inoculation with bacterial inoculants significantly increased the release of antifungal root exudates in a soil type-specific manner; with the highest absolute levels detected on the least-affected LL soil. Soil type-dependent differences were also recorded for the biocontrol effects of the two bacterial inoculants; showing the highest efficiency after double-inoculation on the AL soil. However, this was associated with a reduction of shoot growth and root hair development and a limited micronutrient status of the host plants. Obviously, disease severity and the expression of biocontrol effects are influenced by soil properties with potential impact on reproducibility of practical applications.

Beschreibung: Interest in sustainable alternatives to synthetic nitrogen (N) for switchgrass (Panicum virgatum L.) forage and bioenergy production, such as biological N2 fixation (BNF) via legume-intercropping, continues to increase. The objectives were to: (i) test physical and chemical scarification techniques (10 total) for common vetch (Vicia sativa L.); (ii) assess whether switchgrass yield is increased by BNF under optimum seed dormancy suppression methods; and (iii) determine BNF rates of common and hairy vetch (Vicia villosa L.) via the N-difference method. Results indicate that chemical scarification (sulfuric acid) and mechanical pretreatment (0.7 kg of pressure for one minute) improve common vetch germination by 60% and 50%, respectively, relative to controls. Under optimum scarification methods, BNF was 59.3 and 43.3 kg·N·ha−1 when seeded at 7 kg pure live seed ha−1 for common and hairy vetch, respectively. However, at this seeding rate, switchgrass yields were not affected by BNF (p > 0.05). Based on BNF rates and plant density estimates, seeding rates of 8 and 10 kg pure live seed (PLS) ha−1 for common and hairy vetch, respectively, would be required to obtain plant densities sufficient for BNF at the current recommended rate of 67 kg·N·ha−1 for switchgrass biomass production in the Southeastern U.S.

Beschreibung: The problems of low soil fertility resulting from continuous monocropping, crop residue removal and limited fertilizer use represent key challenges to produce surplus food for the ever increasing population of Ethiopia. However, the practices of crop rotation and integrated sources of fertilizer uses could potentially improve soil fertility and productivity. In 2012 and 2014, soybean with different trials consisting of two soybean varieties (Boshe and Ethio-ugozilavia), three levels of farm yard manure (FYM) (3, 6 and 9 t/ha) and three phosphorus levels (8, 16 and 24 kg P ha−1) were combined in 2 × 3 × 3 factorial arrangements. Two soybean varieties receiving no fertilizer application followed by finger millet receiving a recommended rate (20 kg P/ha) were included. The experiment was laid out in a randomized complete block design with three replications. In 2013 and 2015, finger millet was planted on each soybean plot as per previous treatment arrangements to evaluate the effect of the precursor crop (soybean) and integrated fertilizer application on yield performance of the subsequent finger millet. Soil pH, organic carbon, total nitrogen and available phosphorus before planting and after crop harvest of soybean in each year showed treatment differences. Both precursor crop and fertilizer application had a positive effect on soil fertility status and, hence, improved the performance of the subsequent finger millet. On the other hand, since the rainfall amount and distribution were different in the 2012 and 2014 seasons, the response of soybean varieties to applied fertilizers was significantly affected, and the correlation between soybean yield and annual rainfall was strongly positive. Use of an early maturing soybean variety (Boshe) with the lowest rates of organic and inorganic fertilizers gave significantly higher yield in 2012 (short rainy season) compared with other treatment combinations. In the 2014 cropping season, however, ‘Ethio-ugozilavia’ showed greater yield performance with the combined application of 3 t FYM/ha and 1616 kg PP/ha followed by 3 t FYM and 88 kg P/ha. Hence, it is recommended to use the ‘Boshe’ variety under a short rainy season and under a low soil fertility status, while variety the ‘Ethio-ugozilavia’ can be used under good rainy and soil fertility management conditions. Considering residual effects, the use of the early maturing soybean variety as a precursor with 3 t FYM/ha and 8–16,816 kg P/ha during the short rainy season could enhance the yield of the subsequent finger millet. On the other hand, the use of the late maturing soybean variety as a precursor with higher organic fertilizer rates (6–9 t FYM/ha) resulted in a significant yield increase of the subsequent finger millet. The use of a late maturing variety of soybean with lower rates of organic manure resulted in a finger millet yield comparable to farmers’ practice, indicating that this option can be adopted by smallholder farmers who cannot produce sufficient organic manure. This study showed that planting of finger millet after a soybean precursor crop even without fertilizer application could give better yield and economic benefits as it saves 70%–85% of chemical fertilizer costs compared to the farmers’ practice.

Beschreibung: Stress-inducible genes undergo epigenetic modifications under stress conditions. To investigate if HSP17, of which transcripts accumulate in plant cells under stress, is regulated through epigenetic mechanisms under drought stress, 5-day-old barley (Hordeum vulgare cv. Carina) plants were subjected to progressive drought through water withholding for 22 days. Changes in physiological status and expression of HSP17 gene were monitored in primary leaves of control and drought-treated plants every two days. Twelve days after drought started, control and drought-treated plants were analyzed by chromatin-immunoprecipitation using antibodies against three histone modifications (H3K4me3, H3K9ac, and H3K9me2) and H3 itself. Already after four days of drought treatment, stomatal conductance was severely decreased. Thereafter, maximum and quantum yield of photosystem II (PSII), regulated and non-regulated energy dissipation in PSII, and later also chlorophyll content, were affected by drought, indicating the stress-induced onset of senescence. At the 12th day of drought, before leaf water content declined, expression of HSP17 gene was increased two-fold in drought-treated plants compared to the controls. Twelve days of drought caused an increase in H3 and a loss in H3K9me2 not only at HSP17, but also at constitutively transcribed reference genes ACTIN, PROTEIN PHOSPHATASE 2A (pp2A), and at silent regions BM9, CEREBA. In contrast, H3K4me3 showed a specific increase at HSP17 gene at the beginning and the middle part of the coding region, indicating that this mark is critical for the drought-responsive transcription status of a gene.

Beschreibung: Most of the available research studies have focused on the production of high grain yields of wheat and have neglected yield stability. However, yield stability is a relevant factor in agronomic practice and, therefore, is the focus of this comprehensive survey. The aim was to first describe the importance of yield stability as well as currently used practical management strategies that ensure yield stability in wheat production and secondly, to obtain potential research areas supporting yield stability in the complex system of agronomy. The target groups were German farmers with experience in wheat production and advisors with expertise in the field of wheat cultivation or research. A sample size of 615 completed questionnaires formed the data basis of this study. The study itself provides evidence that the yield stability of winter wheat is even more important than the amount of yield for a large proportion of farmers (48%) and advisors (47%). Furthermore, in the view of the majority of the surveyed farmers and advisors, yield stability is gaining importance in climate change. Data analysis showed that site adapted cultivar choice, favorable crop rotations and integrated plant protection are ranked as three of the most important agronomic management practices to achieve high yield stability of wheat. Soil tillage and fertilization occupied a middle position, whereas sowing date and sowing density were estimated with lower importance. However, yield stability is affected by many environmental, genetic and agronomic factors, which subsequently makes it a complex matter. Hence, yield stability in farming practice must be analyzed and improved in a systems approach.

Beschreibung: Agronomy, Vol. 7, Pages 50: Detection and Response of Sugarcane against the Infection of Sugarcane Mosaic Virus (SCMV) in Indonesia Agronomy doi: 10.3390/agronomy7030050 Authors: Hardian Addy Nurmalasari Agus Wahyudi Ahmil Sholeh Cahya Anugrah Febrian Iriyanto Win Darmanto Bambang Sugiharto Sugarcane mosaic virus (SCMV) is one among many viruses that infect sugarcane, cause yield loss, and become serious disease agents on sugarcane plantations. Since the morphological symptoms of SCMV are similar to other symptoms caused by Sugarcane streak mosaic virus (SCSMV) or nitrogen deficiency, the detection of SCMV is important through accurate diagnostic-like ELISA or RT-PCR. This research aimed to study the causative mosaic pathogen of SCMV in East Java, Indonesia, including mosaic development. The results showed that the mosaic symptom is present in all sugarcane plantations with 78% and 65% disease incidence and severity, respectively. Moreover, the detection procedure based on an amplification of cDNA of the coat protein gene sequence confirmed that SCMV was the causative agent of mosaic disease on sugarcane. Re-inoculation of healthy sugarcane plants with plant sap from a symptomatic leaf from the field showed similar mosaic or yellowish chlorotic areas on the leaf blade, and appeared on the fourth leaves upward from the inoculation leaf, in addition to showing different levels of peroxidase but not total phenol. Mosaic also correlated with the amount of total chlorophyll. Although Sucrose phosphate synthase (SPS) protein accumulation and activity were at a lower level in infected leaves, sucrose accumulation was at a higher level in the same leaves.

Beschreibung: Agronomy, Vol. 7, Pages 51: Evaluation of Agronomic Traits and Drought Tolerance of Winter Wheat Accessions from the USDA-ARS National Small Grains Collection Agronomy doi: 10.3390/agronomy7030051 Authors: Yuxiu Liu Brian Bowman Yin-Gang Hu Xi Liang Weidong Zhao Justin Wheeler Natalie Klassen Harold Bockelman J. Bonman Jianli Chen Wheat accessions from the USDA-ARS National Small Grains Collection (NSGC) are a potential genetic resource for variety improvement. This study assessed the agronomic performance and drought tolerance in 198 winter wheat accessions under irrigated and terminal drought environments in the 2012–2013 season, and repeated the test under terminal drought only during the 2013–2014 season. The 198 accessions were classified into three maturity groups, early, intermediate, and late based on heading data. In all three environments, the early accessions had the best agronomic performance, produced higher grain yield, thousand-kernel weight and grain volume weight, and had earlier heading date and shorter plant height. The intermediate accessions had similar grain yield and thousand-kernel weight as the early accessions in the irrigated environment, but had lower thousand-kernel weight in the terminal drought environments. Terminal drought had significant effects on grain yield, plant height, thousand-kernel weight, and grain volume weight. The positive correlation between GY and HD suggests that the ‘late early’ types in the early maturity were the most successful. Out of 198 accessions evaluated, twenty-three had high yield stability and drought tolerance according to the drought susceptibility index and membership function value of drought tolerance. The eight of twenty-three accessions identified (four early and four intermediate) had high grain yield in three environments. Some of these accessions have been further used in bi-parental mapping studies and by breeders for grain yield and drought tolerance improvement.

Beschreibung: Agronomy, Vol. 7, Pages 52: Variability and Correlations among Groundnut Populations for Early Leaf Spot, Pod Yield, and Agronomic Traits Agronomy doi: 10.3390/agronomy7030052 Authors: Adama Zongo Abel Nana Mahamadou Sawadogo Abdourasmane Konate Philippe Sankara Bonny Ntare Haile Desmae The present experiment was conducted in Mali to study the genetic variability and correlation of early leaf spot (ELS) resistance parameters and agro-morphological traits in groundnut using two F3 populations from crosses QH243C X NAMA and TS32-1 X NAMA. Estimates of genotypic coefficient of variation and phenotypic coefficient of variation revealed high value for pod yield, kernel yield, and ELS score at 60 and 80 days after sowing for the cross QH243C X NAMA. Low-to-moderate GCV and PCV were obtained for the remaining traits for both crosses. High heritability values coupled with high genetic advance as percentage of mean recorded for ELS_II, defoliation percent, pod yield in cross QH243C X NAMA; shelling percent for the cross TS32-1 X NAMA and ELS_III; and plant height, kernel yield in both crosses, indicate the significant role of additive gene action for inheritance of these traits. Correlation analysis indicated that pod and kernel yield were significant and positively correlated with 100 kernel weight and shelling percent. For cross QH243C X NAMA, kernel yield showed significant positive correlation with all ELS resistance components but the correlation was not significant for the cross TS32-1 X NAMA. Positive and significant correlation was observed between ELS resistance components themselves, suggesting that these components could be controlled by a similar polygenic system. The findings suggest that early generation selection should be effective for days to first flowering, days to 50% flowering, plant height, pod yield, kernel yield, 100 kernel weight and early leaf spot resistance which recorded the highest value of heritability in the two crosses.

Beschreibung: Agronomy, Vol. 7, Pages 53: Characterisation of Faba Bean (Vicia faba L.) Transcriptome Using RNA-Seq: Sequencing, De Novo Assembly, Annotation, and Expression Analysis Agronomy doi: 10.3390/agronomy7030053 Authors: Shivraj Braich Shimna Sudheesh John Forster Sukhjiwan Kaur RNA sequencing (RNA-Seq) is a deep sequencing method used for transcriptome profiling. RNA-Seq assemblies have successfully been used for a broad variety of applications, such as gene characterisation, functional genomic studies, and gene expression analysis, particularly useful in the absence of a well-studied genome reference sequence. This study reports on the development of reference unigene sets from faba bean using RNA-Seq. Two Australian faba bean cultivars (Doza and Farah) that differ in terms of disease resistance, breeding habit, and adaptation characteristics, and have been extensively used in breeding programs, were utilised in this study. The de novo assembly resulted in a total of 58,962 and 53,275 transcripts with approximately 67 Mbp (1588 bp N50) and 61 Mbp (1629 bp N50) for Doza and Farah, respectively. The generated transcripts have been compared to the protein and nucleotide databases of NCBI, as well as to the gene complements of several related legume species such as Medicago truncatula, soybean, and chickpea. Both assemblies were compared to previously-published faba bean transcriptome reference sets for the degree of completeness and utility. Annotation of unigenes has been performed, and patterns of tissue-specific expression identified. The gene complement derived from this comprehensive transcriptome analysis shows that faba bean, despite its complex 13 Gbp genome, compares well to other legumes in expressed gene content. This study in faba bean represents the most comprehensive reference transcriptomes from two different Australian cultivars available to date and it provides a valuable resource for future genomics-assisted breeding activities in this species.

Beschreibung: Agronomy, Vol. 7, Pages 66: Investigating the Combined Effect of Tillage, Nitrogen Fertilization and Cover Crops on Nitrogen Use Efficiency in Winter Wheat Agronomy doi: 10.3390/agronomy7040066 Authors: Hazzar Habbib Bertrand Hirel Julien Verzeaux David Roger Jérôme Lacoux Peter Lea Frédéric Dubois Thierry Tétu A field study was conducted in northern France over two consecutive years to evaluate the combined effect of conventional tillage (CT) vs no till (NT) with or without cover crops (cc) and nitrogen (N) fertilization on various agronomic traits related to N use efficiency in winter wheat. Five years after conversion of CT to NT, significant increases in N use efficiency, N utilization efficiency, N agronomic efficiency, N partial factor productivity, N apparent recovery fraction and N remobilization were observed under three N fertilization regimes (0, 161, 215 kg ha−1). It was also observed that grain yield and grain N content were similar under CT and NT. The N nutrition index was higher under NT at the three rates of N fertilization. Moreover, N use efficiency related traits were increased in the presence of cc both under NT and CT. Thus, agronomic practices based on continuous NT in the presence of cc, appear to be promising strategies to increase N use efficiency in wheat, while reducing both the use and the loss of N-based fertilizers.

Beschreibung: Agronomy, Vol. 7, Pages 67: Arsenic Accumulation in Rice and Probable Mitigation Approaches: A Review Agronomy doi: 10.3390/agronomy7040067 Authors: Anindita Mitra Soumya Chatterjee Roxana Moogouei Dharmendra Gupta According to recent reports, millions of people across the globe are suffering from arsenic (As) toxicity. Arsenic is present in different oxidative states in the environment and enters in the food chain through soil and water. In the agricultural field, irrigation with arsenic contaminated water, that is, having a higher level of arsenic contamination on the top soil, which may affects the quality of crop production. The major crop like rice (Oryza sativa L.) requires a considerable amount of water to complete its lifecycle. Rice plants potentially accumulate arsenic, particularly inorganic arsenic (iAs) from the field, in different body parts including grains. Different transporters have been reported in assisting the accumulation of arsenic in plant cells; for example, arsenate (AsV) is absorbed with the help of phosphate transporters, and arsenite (AsIII) through nodulin 26-like intrinsic protein (NIP) by the silicon transport pathway and plasma membrane intrinsic protein aquaporins. Researchers and practitioners are trying their level best to mitigate the problem of As contamination in rice. However, the solution strategies vary considerably with various factors, such as cultural practices, soil, water, and environmental/economic conditions, etc. The contemporary work on rice to explain arsenic uptake, transport, and metabolism processes at rhizosphere, may help to formulate better plans. Common agronomical practices like rain water harvesting for crop irrigation, use of natural components that help in arsenic methylation, and biotechnological approaches may explore how to reduce arsenic uptake by food crops. This review will encompass the research advances and practical agronomic strategies on arsenic contamination in rice crop.

Beschreibung: Agronomy, Vol. 7, Pages 74: Resistance to Wheat Curl Mite in Arthropod-Resistant Rye-Wheat Translocation Lines Agronomy doi: 10.3390/agronomy7040074 Authors: Lina Aguirre-Rojas Luaay Khalaf Sandra Garcés-Carrera Deepak Sinha Wen-Po Chuang C. Smith The wheat curl mite, Aceria toschiella (Keifer), and a complex of viruses vectored by A. toschiella substantially reduce wheat yields in every wheat-producing continent in the world. The development of A. toschiella-resistant wheat cultivars is a proven economically and ecologically viable method of controlling this pest. This study assessed A. toschiella resistance in wheat genotypes containing the H13, H21, H25, H26, H18 and Hdic genes for resistance to the Hessian fly, Mayetiola destructor (Say) and in 94M370 wheat, which contains the Dn7 gene for resistance to the Russian wheat aphid, Diuraphis noxia (Kurdjumov). A. toschiella populations produced on plants containing Dn7 and H21 were significantly lower than those on plants of the susceptible control and no different than those on the resistant control. Dn7 resistance to D. noxia and H21 resistance to M. destructor resulted from translocations of chromatin from rye into wheat (H21—2BS/2RL, Dn7—1BL/1RS). These results provide new wheat pest management information, indicating that Dn7 and H21 constitute resources that can be used to reduce yield losses caused by A. toschiella, M. destructor, D. noxia, and wheat streak mosaic virus infection by transferring multi-pest resistance to single sources of germplasm.

Beschreibung: Agronomy, Vol. 7, Pages 81: Starch Biosynthesis in the Developing Endosperms of Grasses and Cereals Agronomy doi: 10.3390/agronomy7040081 Authors: Ian Tetlow Michael Emes The starch-rich endosperms of the Poaceae, which includes wild grasses and their domesticated descendents the cereals, have provided humankind and their livestock with the bulk of their daily calories since the dawn of civilization up to the present day. There are currently unprecedented pressures on global food supplies, largely resulting from population growth, loss of agricultural land that is linked to increased urbanization, and climate change. Since cereal yields essentially underpin world food and feed supply, it is critical that we understand the biological factors contributing to crop yields. In particular, it is important to understand the biochemical pathway that is involved in starch biosynthesis, since this pathway is the major yield determinant in the seeds of six out of the top seven crops grown worldwide. This review outlines the critical stages of growth and development of the endosperm tissue in the Poaceae, including discussion of carbon provision to the growing sink tissue. The main body of the review presents a current view of our understanding of storage starch biosynthesis, which occurs inside the amyloplasts of developing endosperms.

Beschreibung: Agronomy, Vol. 7, Pages 73: A Dynamic Decision-Making Tool for Calculating the Optimal Rates of N Application for 40 Annual Crops While Minimising the Residual Level of Mineral N at Harvest Agronomy doi: 10.3390/agronomy7040073 Authors: Jean-Marie Machet Pascal Dubrulle Nathalie Damay Rémy Duval Jean-Luc Julien Sylvie Recous Adequate nitrogen (N) fertilisation is an important component of sustainable management in agricultural systems because it reduces the environmental impacts of agriculture. However, taking into account the varied sources of soil N remains a challenge, and farmers require robust decision-making tools to manage increasingly diverse growing conditions. To address these issues, we present the AzoFert® decision support system for farmers and extension services. This tool is capable of providing N recommendations at the field scale for 40 main field crops. It is based on a full inorganic N balance sheet and integrates the dynamic modelling of N supply from soil and various organic sources. Because of the choice of formalisms and parameters and the structure and modularity of the computer design, the tool is easily adaptable to new crops and cropping systems. We illustrate the application of Azofert® through a range of N fertilisation experiments conducted on cereals, sugar beet and vegetables in France.

Beschreibung: Agronomy, Vol. 7, Pages 75: Trade-Offs in Arbuscular Mycorrhizal Symbiosis: Disease Resistance, Growth Responses and Perspectives for Crop Breeding Agronomy doi: 10.3390/agronomy7040075 Authors: Catherine Jacott Jeremy Murray Christopher Ridout There is an increasing need to develop high-yielding, disease-resistant crops and reduce fertilizer usage. Combining disease resistance with efficient nutrient assimilation through improved associations with symbiotic microorganisms would help to address this. Arbuscular mycorrhizal fungi (AMF) form symbiotic relationships with most terrestrial plants, resulting in nutritional benefits and the enhancement of stress tolerance and disease resistance. Despite these advantages, arbuscular mycorrhizal (AM) interactions are not normally directly considered in plant breeding. Much of our understanding of the mechanisms of AM symbiosis comes from model plants, which typically exhibit positive growth responses. However, applying this knowledge to crops has not been straightforward. In many crop plants, phosphate uptake and growth responses in AM-colonized plants are variable, with AM plants exhibiting sometimes zero or negative growth responses and lower levels of phosphate acquisition. Host plants must also balance the ability to host AMF with the ability to resist pathogens. Advances in understanding the plant immune system have revealed similarities between pathogen infection and AM colonization that may lead to trade-offs between symbiosis and disease resistance. This review considers the potential trade-offs between AM colonization, agronomic traits and disease resistance and highlights the need for translational research to apply fundamental knowledge to crop improvement.

Beschreibung: Agronomy, Vol. 7, Pages 79: Determination of Micronutrient Accumulation in Greenhouse Cucumber Crop Using a Modeling Approach Agronomy doi: 10.3390/agronomy7040079 Authors: Lino Ramírez-Pérez América Morales-Díaz Karim de Alba-Romenus Susana González-Morales Adalberto Benavides-Mendoza Antonio Juárez-Maldonado The control of micronutrient application in cucumber cultivation has great importance as they participate in many functions of metabolism. In addition, micronutrient application efficiency is fundamental to avoid periods of overconsumption or deficits in the crop. To determine micronutrient accumulation using a dynamic model, two cycles of Vitaly and Luxell cucumber crops were grown. During the development of the crop, micronutrient content (Fe, B, Mn, Cu, and Zn) in the different organs of the cucumber plant was quantified. The model dynamically simulated the accumulation of biomass and micronutrients using climatic variables recorded inside the greenhouse as inputs. It was found that a decrease in photosynthetically active radiation and temperature significantly diminished the accumulation of biomass by the cucumber plants. On the other hand, the results demonstrated that the model efficiently simulated both the accumulation of biomass and micronutrients in a cucumber crop. The efficiency evaluation showed values higher than R2 > 0.95. This dynamic model can be useful to define adequate strategies for the management of cucumber cultivation in greenhouses as well as the application of micronutrients.

Beschreibung: Agronomy, Vol. 7, Pages 77: Nitrogen Sources and Rates Affect Soybean Seed Composition in Mississippi Agronomy doi: 10.3390/agronomy7040077 Authors: Gurpreet Kaur William Serson John Orlowski Justin McCoy Bobby Golden Nacer Bellaloui Soybean (Glycine max L.) seed is a major source of protein, oil, carbohydrates and other nutrients that are important for human and animal nutrition. Producers have considered applying nitrogen (N) fertilizer to soybean crop to maximize seed yield; however, its effect on seed composition is not well understood. The objective of this two-year (2015 and 2016) study was to evaluate the effects of N fertilizer sources and application rates (45, 90, 135 and 179 kg N ha−1) on soybean seed composition on two soil textures (clay and silt-loam) in Mississippi. The three fertilizer sources included in this study were urea with N-(n butyl) thiophosphoric triamide (Urea+NBPT), polymer-coated urea (PCU), and ammonium sulfate (AMS). Nitrogen application at 179 kg ha−1 on clay soil reduced seed protein by 1.05% compared to unfertilized soybeans in 2016. However, N application at 179 kg ha−1 increased oil content by 0.7% on clay soil compared to the unfertilized soybeans only in 2016. Nitrogen applications reduced stachyose content on both soil textures in 2015. The fatty acids showed variable response to N applications. Since, seed quality is not a trait from which growers receive an economic incentive, they are unlikely to adopt this practice for standard soybean production.

Beschreibung: Agronomy, Vol. 7, Pages 76: Assessment of Soil Aggradation through Soil Aggregation and Particulate Organic Matter by Riparian Switchgrass Buffers Agronomy doi: 10.3390/agronomy7040076 Authors: Carmen Márquez Víctor García Richard Schultz Tom Isenhart The restoration of riparian zones has been an important issue in many regions for the recovery of ecosystem functions. The objective of this study was to assess soil aggradation in a 7-year established riparian switchgrass buffer (SGB) and in a non-buffered riparian zone with an annual row crop (ARC). We measured the aggregate size distribution and stability of macroaggregates, aggregate-associated soil organic carbon, soil organic matter fractions and the chemical composition of light particulate organic matter to monitor soil aggregation in a riparian soil following the conversion of agricultural row crops to switchgrass filters. Aggregate size fractions were separated by wet sieving using the aggregate size-stability protocol. The proportion of soil and total organic C was quantified for each aggregate size class. Soil organic matter fractions were isolated by size and density into light particulate organic matter and heavy particulate organic matter and mineral fraction organic matter. The categorization of aggregates by size and water stability (slaking resistance) showed a significantly larger (p < 0.001) proportion of water-unstable large macroaggregates (>2000 µm) under SGB (34%) compared to that under ARC (29%), while the proportion of water-unstable small macroaggregates (250–2000 µm) was significantly higher under ARC (14%) than under SGB (10%). Our results showed that the amounts of light and heavy particulate organic matter did not change in the short-term (7 years) after SGB establishment. It appears that the lower soil stabilization and soil organic C storage under SGB is related to (i) the large number of coarse roots; (ii) lower inputs of light and heavy particulate organic matter; (iii) no changes in the alkyl-C/O-alkyl-C ratio over time; and (iv) light particulate organic matter with a high C/N ratio.

Beschreibung: Agronomy, Vol. 7, Pages 78: In-Vitro Inhibition of Pythium ultimum, Fusarium graminearum, and Rhizoctonia solani by a Stabilized Lactoperoxidase System alone and in Combination with Synthetic Fungicides Agronomy doi: 10.3390/agronomy7040078 Authors: Zachariah Hansen Marie Donnelly Stéphane Corgié Advances in enzyme stabilization and immobilization make the use of enzymes for industrial applications increasingly feasible. The lactoperoxidase (LPO) system is a naturally occurring enzyme system with known antimicrobial activity. Stabilized LPO and glucose oxidase (GOx) enzymes were combined with glucose, potassium iodide, and ammonium thiocyanate to create an anti-fungal formulation, which inhibited in-vitro growth of the plant pathogenic oomycete Pythium ultimum, and the plant pathogenic fungi Fusarium graminearum and Rhizoctonia solani. Pythium ultimum was more sensitive than F. graminearum and R. solani, and was killed at LPO and GOx concentrations of 20 nM and 26 nM, respectively. Rhizoctonia solani and F. graminearum were 70% to 80% inhibited by LPO and GOx concentrations of 242 nM and 315 nM, respectively. The enzyme system was tested for compatibility with five commercial fungicides as co-treatments. The majority of enzyme + fungicide co-treatments resulted in additive activity. Synergism ranging from 7% to 36% above the expected additive activity was observed when P. ultimum was exposed to the enzyme system combined with Daconil® (active ingredient (AI): chlorothalonil 29.6%, GardenTech, Lexington, KY, USA), tea tree oil, and mancozeb at select fungicide concentrations. Antagonism was observed when the enzyme system was combined with Tilt® (AI: propiconazole 41.8%, Syngenta, Basel, Switzerland) at one fungicide concentration, resulting in activity 24% below the expected additive activity at that concentration.

Beschreibung: Agronomy, Vol. 7, Pages 80: Breeding for Quality Protein Maize (QPM) Varieties: A Review Agronomy doi: 10.3390/agronomy7040080 Authors: Liliane N. Tandzi Charles S. Mutengwa Eddy L. M. Ngonkeu Noé Woïn Vernon Gracen The nutritional evaluation of quality protein maize (QPM) in feeding trials has proved its nutritional superiority over non-QPM varieties for human and livestock consumption. The present paper reviews some of the most recent achievements in development of QPM varieties using both conventional and molecular breeding under stressed and non-stressed environments. It is evident that numerous QPM varieties have been developed and released around the world over the past few decades. While the review points out some gaps in information or research efforts, challenges associated with adoption QPM varieties are highlighted and suggestions to overcome them are presented. The adoption of released varieties and challenges facing QPM production at the farmer level are also mentioned. Several breeding methods have been conventionally used to develop QPM varieties in stressed (drought, low soil nitrogen, resistance to grey leaf spot, Turcicum leaf blight, ear rot, and Striga) and non-stressed environments. At least three genetic loci have been found to be implicated in controlling the levels of a protein synthesis factor correlated with lysine. They have been mapped on chromosomes 2, 4, and 7. While the use of molecular approaches will improve the efficiency and speed of variety development, the cost implications might limit the use of these technologies in the developing world. More emphasis should be given to breeding QPM for tolerance to environmental stresses, such as low soil pH, heat, and combined heat and drought stress. The post-harvest attack of QPM grains should also be considered. The adoption of QPM genotypes by farmers has been found to be limited mainly due to the minimal collaboration between maize breeders, farmers, agricultural extension workers, and other relevant stakeholders, as well as the need for isolating QPM varieties from normal maize. Therefore, there is need to use participatory plant breeding (PPB) and/or participatory variety selection (PVS) to enhance and improve the adoption of QPM varieties.

Beschreibung: Agronomy, Vol. 7, Pages 70: Prospects for Genetic Improvement in Internal Nitrogen Use Efficiency in Rice Agronomy doi: 10.3390/agronomy7040070 Authors: Terry Rose Tobias Kretzschmar Daniel L. E. Waters Jeanette Balindong Matthias Wissuwa While improving the efficiency at which rice plants take up fertiliser nitrogen (N) will be critical for the sustainability of rice (Oryza sativa L.) farming systems in future, improving the grain yield of rice produced per unit of N accumulated in aboveground plant material (agronomic N use efficiency; NUEagron) through breeding may also be a viable means of improving the sustainability of rice cropping. Given that NUEagron (grain yield/total N uptake) is a function of harvest index (HI; grain yield/crop biomass) × crop biomass/total N uptake, and that improving HI is already the target of most breeding programs, and specific improvement in NUEagron can only really be achieved by increasing the crop biomass/N uptake. Since rice crops take up around 80% of total crop N prior to flowering, improving the biomass/N uptake (NUEveg) prior to, or at, flowering may be the best means to improve the NUEagron. Ultimately, however, enhanced NUEagron may come at the expense of grain protein unless the N harvest index increases concurrently. We investigated the relationships between NUEagron, total N uptake, grain yield, grain N concentration (i.e., protein) and N harvest index (NHI) in 16 rice genotypes under optimal N conditions over two seasons to determine if scope exists to improve the NHI and/or grain protein, while maintaining or enhancing NUEagron in rice. Using data from these experiments and from an additional experiment with cv. IR64 under optimum conditions at an experimental farm to establish a benchmark for NUE parameters in high-input, high yielding conditions, we simulated theoretical potential improvements in NUEveg that could be achieved in both low and high-input scenarios by manipulating target NHIs and grain protein levels. Simulations suggested that scope exists to increase grain protein levels in low yielding scenarios with only modest (5–10%) reductions in current NUEagron by increasing the current NHI from 0.6 to 0.8. Furthermore, substantial scope exists to improve NUEveg (and therefore NUEagron) in high-yielding scenarios if maintaining current grain protein levels of 7.3% is not essential.

Beschreibung: Agronomy, Vol. 7, Pages 69: Reducing Severity of Late Blight (Phytophthora infestans) and Improving Potato (Solanum tuberosum L.) Tuber Yield with Pre-Harvest Application of Calcium Nutrients Agronomy doi: 10.3390/agronomy7040069 Authors: Yewubnesh Wendimu Seifu The efficiency of pre-harvest application of calcium chloride alone, calcium nitrate alone, and combined application of calcium chloride and calcium nitrate (1:1) was evaluated in reducing the severity of P. infestans and improving potato tuber yield. Pot experiment was conducted in randomized complete block design with four replications. The treatments consisted of combination of two potato varieties (Shenkola and Gera) and three types of calcium nutrients (calcium chloride alone, calcium nitrate alone, and calcium chloride mixed with calcium nitrate), each at three levels (5, 10, and 15 g per liter per plant) and the control treatment (0 g of calcium nutrients). In comparison to the control treatment, the application of calcium nutrients significantly decreased the severity of late blight disease and improved potato tuber yield. The effect of calcium nutrients on the severity of late blight disease and potato tuber yield differed among the two potato varieties. The maximum severity reduction (60%) was noticed in the Gera potato variety with the application of calcium chloride mixed with calcium nitrate (1:1), supplied at 15 g per plant. However, the highest average tuber yield was obtained with the application of calcium nitrate at 15 g per plant, and average tuber yield was increased by 77% in both potato varieties. Hence, foliar application of either calcium nitrate alone or calcium nitrate mixed with calcium chloride was found to be more efficient than the application of calcium chloride alone. This result suggests that the nitrate ion present in the calcium nitrate may make a difference in terms of reducing the severity of late blight disease and improving potato tuber yield. The lowered severity of late blight disease and the increased tuber yield in potato plants sprayed with calcium nutrients may be because of the higher accumulation of calcium in the plant tissue.

Beschreibung: Agronomy, Vol. 7, Pages 72: Genotypic Response of Dry Bean (Phaseolus vulgaris L.) to Natural Field Infection of Ascochyta Blight (Phoma exigua var. diversispora (Bubak) Boerema) under Diverse Environmental Conditions in Rwanda Agronomy doi: 10.3390/agronomy7040072 Authors: Clement Urinzwenimana Rob Melis Julia Sibiya Ascochyta blight, caused by Phoma exigua var. diversispora (Bubak) Boerema, is a serious constraint in the cultivation of the common bean (Phaseolus vulgaris L.) in Rwanda, particularly in the cool and wet highland production areas. In order to identify resistant genotypes, a germplasm evaluation study was conducted to quantify the impact of the disease on phenotypic and agronomic traits under natural conditions. Field screening trials of 39 bush (Types I, II and III) and 36 climbing (Type IV) genotypes from different accessions within and outside the country were conducted at three sites, namely, Rwerere, Nyamagabe and Musanze Research Stations, for two seasons. The relative area under the disease progress curve (RAUDPC) based on evaluations of the disease severity (percentage leaf area infected), was used to evaluate the genotypes. Thirteen genotypes were identified with some level of ascochyta resistance. The study revealed Rwandan genotypes G 2333 and SMC 18 as new sources of resistance to Ascochyta blight. Additional results showed a negative relationship (r = −0.42 and −0.51 for Seasons A and B, respectively) between ascochyta infection and yield. Further relationships were identified between the plant flower colour and seed size to ascochyta resistance. Some of the identified resistant genotypes can be used to introgress ascochyta resistance into susceptible Rwandan market classes of common bean genotypes.

Beschreibung: Agronomy, Vol. 8, Pages 1: Soil Factors Effects on the Mineralization, Extractable Residue, and Bound Residue Formation of Aminocyclopyrachlor in Three Tropical Soils Agronomy doi: 10.3390/agronomy8010001 Authors: Jeane Francisco Kassio Mendes Rodrigo Pimpinato Valdemar Tornisielo Ana Guimarães Aminocyclopyrachlor is an herbicide that belongs to the new class of chemicals known as the pyrimidine carboxylic acids, which are used to control broadleaf weeds and brush. However, the environmental behavior and fate of aminocyclopyrachlor are not fully understood. The aim of the present study was thus to evaluate the mineralization, extractable residue and bound residue formation of aminocyclopyrachlor in three tropical soils with different physico-chemical properties. 14C-labeled [pyrimidine-2-14C] aminocyclopyrachlor was used to assess the fate of this herbicide in soil placed in biometer culture flasks. Total mineralization (accumulated 14CO2) of aminocyclopyrachlor was found to be <10% in all soils, decreasing in the following order: Oxisol—Typic Hapludox (clay) > Oxisol—Typic Hapludox (loamy sand) > Plinthosol—Petric (sandy clay). Overall, constant rate of mineralization (k) values for all soils were very low (0.00050% to 0.00079% 14CO2 d−1), with mineralization half-life times (MT50) consequently very high (877 to 1376 days), suggesting potential long persistence in soil. The amount of extractable residues decreased from ~31% to 50% in all soils after 126 days of incubation, indicating an increase in bound residue formation from ~5.0- to 7.5-fold compared to evaluation immediately after herbicide application, suggesting that degradation herbicide is involved in the formation of bound residues. Extractable residues are important factors that control mineralization and bound residue formation from aminocyclopyrachlor in the soil. The present study is the first to assess the fate, distribution, and formation of bound residues of aminocyclopyrachlor in soils. Aminocyclopyrachlor residues were predominantly associated with the OM and clay contents of soil. This effect of soil physico-chemical properties should be considered in environmental risk assessment of aminocyclopyrachlor and its application in the field for weed control.

Beschreibung: Agronomy, Vol. 7, Pages 85: A Case Study of Potential Reasons of Increased Soil Phosphorus Levels in the Northeast United States Agronomy doi: 10.3390/agronomy7040085 Authors: Lakesh Sharma Sukhwinder Bali Ahmed Zaeen Recent phosphorus (P) pollution in the United States, mainly in Maine, has raised some severe concerns over the use of P fertilizer application rates in agriculture. Phosphorus is the second most limiting nutrient after nitrogen and has damaging impacts on crop yield if found to be deficient. Therefore, farmers tend to apply more P than is required to satisfy any P loss after its application at planting. Several important questions were raised in this study to improve P efficiency and reduce its pollution. The objective of this study was to find potential reasons for P pollution in water bodies despite a decrease in potato acreage. Historically, the potato was found to be responsible for P water contamination due to its high P sensitivity and low P removal (25–30 kg ha−1) from the soil. Despite University of Maine recommended rate of 56 kg ha−1 P, if soil tests reveal that P is below 50 kg ha−1, growers tend to apply P fertilizer at the rate of 182 kg ha−1 to compensate for any loss. The second key reason for excessive P application is its tendency to get fixed by aluminum (Al) in the soil. Soil sampling data from UMaine Soil Testing Laboratory confirmed that in Maine reactive Al levels have remained high over the last ten years and are increasing further. Likewise, P application to non-responsive sites, soil variability, pH change, and soil testing methods were found to be other possible reasons that might have led to increases in soil P levels resulting in P erosion to water streams.

Beschreibung: Agronomy, Vol. 7, Pages 86: Assessing Genotype-By-Environment Interactions in Aspergillus Ear Rot and Pre-Harvest Aflatoxin Accumulation in Maize Inbred Lines Agronomy doi: 10.3390/agronomy7040086 Authors: Sheila Okoth Lindy Rose Abigael Ouko Nakisani Netshifhefhe Henry Sila Altus Viljoen Aspergillus flavus, causal agent of the Aspergillus ear rot (AER) of maize, also produces aflatoxins that cause aflatoxicosis in humans and livestock. Ten maize inbred lines were evaluated in replicated trials in two aflatoxicosis outbreak hot spots in Kenya and in three maize-growing areas in South Africa for resistance to AER, A. flavus colonization, and pre-harvest aflatoxin accumulation during the 2012/13 growing season. AER severity was measured by visual assessment, while A. flavus colonization and aflatoxin content were quantified by real-time polymerase chain reaction (PCR) and liquid chromatography tandem mass spectrometry, respectively. Genotype by environment interaction (GEI) was determined using analysis of variance (ANOVA), additive main effects and multiplicative models (AMMI), and genotype plus by environment (GGE) biplot analyses. Stability of genotypes was evaluated using AMMI analysis. AER severity and fungal colonization significantly (p < 0.001) varied between genotypes. GEI influenced the severity of AER symptoms and aflatoxin accumulation significantly (p < 0.001), while fungal colonization was not affected. The inbred lines response was consistent for this trait in the test environments and was thus considered a desirable measure to indicate maize lines with a high risk of aflatoxin accumulation. CML495, CKL05019, LaPosta, and MIRTC5 were the least diseased lines, with the lowest aflatoxin contamination and a stable phenotypic response across the environments. Kiboko was determined as the ideal representative test environment, with discriminative ability of the genotypes for selection of the desired stable responses of the three traits.

Beschreibung: Agronomy, Vol. 8, Pages 2: Generation of Transgenic Rootstock Plum ((Prunus pumila L. × P. salicina Lindl.) × (P. cerasifera Ehrh.)) Using Hairpin-RNA Construct for Resistance to the Plum pox virus Agronomy doi: 10.3390/agronomy8010002 Authors: Tatiana Sidorova Alexander Pushin Dmitry Miroshnichenko Sergey Dolgov The use of Prunus rootstocks that are resistant to plum pox virus (PPV) is an important agronomic strategy to combat the spread of the Sharka disease in nurseries and orchards. Despite remarkable progress in developing stone fruit rootstocks to adapt to various stresses, breeding that ensures durable virus resistance has not yet been achieved. For this reason, the engineering of PPV resistant plants through genetic transformation is a very promising approach to control sharka disease. The aim of the present study is to produce transgenic plants of the clonal rootstock ‘Elita’, which is resistant to PPV using ribonucleic acid interference (RNAi) technology. The genetic construct containing the self-complementary fragments of the plum pox virus coat protein (PPV-CP) gene sequence were used to induce the mechanism of post-transcriptional gene silencing to ensure virus resistance. Transgenic plants have been produced after agrobacterium-mediated transformation of in vitro explanted leaves. The results of polymerase chain reaction (PCR) and Southern blotting analyses confirmed the stable genomic integration of the PPV-CP sense and antisense intron-hairpin-RNA sequence. The functionality of the introduced expression cassette was confirmed by the activity of including the uidA gene into the transferring T-DNA. To our knowledge, this is the first interspecific plum rootstock produced by genetic engineering to achieve PPV resistance.

Beschreibung: Agronomy, Vol. 8, Pages 3: Effect of Water Deficit-Induced at Vegetative and Reproductive Stages on Protein and Oil Content in Soybean Grains Agronomy doi: 10.3390/agronomy8010003 Authors: Liliane Mertz-Henning Leonardo Ferreira Fernando Henning José Mandarino Elizeu Santos Maria Oliveira Alexandre Nepomuceno José Farias Norman Neumaier Soybean is one of the most common grain crops worldwide, representing an important protein and oil source. Although genetic variability in the chemical composition of grains is seen in soybean, the mean levels of proteins have remained stagnant or, in some cases, have decreased over time, arousing concern in the agricultural industry. Furthermore, environmental conditions influence the chemical composition of grains. Thus, the present study evaluated the effect of water deficit (WD) induced at the vegetative period (vegetative stress (VS)) and reproductive period (reproductive stress (RS)) on the protein and oil contents of grains in different soybean genotypes. Yield and its components were evaluated to evaluate the interrelation of these traits. The experiment was completed over three crop seasons under field conditions in Londrina, Paraná (PR), Brazil. WD was induced using rainout shelters and then stress treatments with irrigated and non-irrigated conditions were compared. WD negatively affected yield and its components. All evaluated genotypes showed similar responses for oil and protein contents under different water conditions. Higher protein content and lower oil content were observed in grains under RS. Such a relationship was not equally established under VS. Additionally, negative relationships between protein and oil content and between protein content and yield were confirmed.

Beschreibung: Agronomy, Vol. 7, Pages 71: Artificial Seeds (Principle, Aspects and Applications) Agronomy doi: 10.3390/agronomy7040071 Authors: Hail Rihan Fakhriya Kareem Mohammed El-Mahrouk Michael Fuller Artificial seeds are artificially encapsulated somatic embryos (usually) or other vegetative parts such as shoot buds, cell aggregates, auxiliary buds, or any other micropropagules which can be sown as a seed and converted into a plant under in vitro or in vivo conditions. An improved artificial seed production technique is considered a valuable alternate technology of propagation in many commercially important crops and a significant method for mass propagation of elite plant genotypes. The production of plant clones multiplied by tissue culture and distributed as artificial seeds could be a useful alternative to the costly F1 hybrids for different plant crops. The delivery of artificial seeds also facilitates issues such as undertaking several ways for scaling up in vitro cultures and acclimatization to ex vitro conditions. The development of an artificial seed technique also provides a great approach for the improvement of various plant species such as trees and crops.

Beschreibung: Adaptation can be a key factor that will shape the future severity of climate change impacts on food production. The objective of this study was to assess the suitability of an agro-ecological approach based on various techniques as potential adaptation strategy in organic horticultural systems. A long-term field experiment was set up in Southern Italy, combining: (i) appropriate soil surface shaping; (ii) cash crop rotation; (iii) agro-ecological service crops (ASC) introduction as living mulch and complementary crops; (iv) tailored organic fertilization; and (v) alternative tillage strategies. In this paper, the first two-year results on cauliflower (Brassica oleracea L.) and tomato (Solanum lycopersicum L.) crops, as well as energy consumptions through the Energy Analysis (EA) method are reported. Due to the climatic conditions that occurred, which were characterized by the absence of extreme climatic events (particularly rainfall), it was not possible to verify if the designed experimental device was able to mitigate the impact of climate change, whereas the EA indicated that total energy inputs were lower when ASC are introduced in cropping systems.

Beschreibung: Agronomic characteristics and phytoestrogen concentrations were measured on 17 cultivars and 47 accessions of red clover (Trifolium pratense). These accessions included a range of currently recommended cultivars—from Australia and overseas—and germplasm accessed from genetic resource collections. All lines were grown in the field at Hamilton Vic in 2000 and 2001. Significant genetic variation was detected for key agronomic parameters such as growth habit, leaf shape and markings, leaf area, herbage yield, flowering time, and prolificacy. Significant variation in the concentration of the four main phytoestrogens was found; total isoflavone concentration ranged from 0.14–1.45% DM. Maximum concentrations of daidzein, genistein, formononetin, and biochanin were 0.06, 0.08, 0.86, and 0.91% DM respectively. Multivariate analysis showed that the accessions grouped into 10 distinct clusters that had between 1 and 10 members. Several accessions were superior to existing cultivars—notably Mediterranean accessions with regard to cool season vigour—and valuable for breeding programs to develop high yielding cultivars with either high (for possible medicinal purposes) or low (for grazing) phytoestrogen concentrations.

Beschreibung: Elevated carbon dioxide (eCO2) stimulates wheat grain yield, but simultaneously reduces protein/nitrogen (N) concentration. Also, other essential nutrients are subject to change. This study is a synthesis of wheat experiments with eCO2, estimating the effects on N, minerals (B, Ca, Cd, Fe, K, Mg, Mn, Na, P, S, Zn), and starch. The analysis was performed by (i) deriving response functions to assess the gradual change in element concentration with increasing CO2 concentration, (ii) meta-analysis to test the average magnitude and significance of observed effects, and (iii) relating CO2 effects on minerals to effects on N and grain yield. Responses ranged from zero to strong negative effects of eCO2 on mineral concentration, with the largest reductions for the nutritionally important elements of N, Fe, S, Zn, and Mg. Together with the positive but small and non-significant effect on starch concentration, the large variation in effects suggests that CO2-induced responses cannot be explained only by a simple dilution model. To explain the observed pattern, uptake and transport mechanisms may have to be considered, along with the link of different elements to N uptake. Our study shows that eCO2 has a significant effect on wheat grain stoichiometry, with implications for human nutrition in a world of rising CO2.

Beschreibung: The growth of the blueberry industry in the past three decades has been remarkably robust. However, a labor shortage for hand harvesting, increasingly higher labor costs, and low harvest efficiencies are becoming bottlenecks for sustainable development of the fresh market blueberry production. In this study, we evaluated semi-mechanical harvesting systems consisting of a harvest-aid platform with soft fruit catching surfaces that collected the fruit detached by portable, hand-held, pneumatic shakers. The softer fruit catching surfaces were not glued to the hard sub-surfaces of the harvest-aid platform, but suspended over them. Also, the ergonomic aspect of operating powered harvesting equipment was determined. The pneumatic shakers removed 3.5 to 15 times more fruit (g/min) than by hand. Soft fruit catching surfaces reduced impact force and bruise damage. Fruit firmness was higher in fruit harvested by hand compared to that by pneumatic shakers in some cultivars. The bruise area was less than 8% in fruit harvested by hand and with semi-mechanical harvesting system. The percentage of blue, packable fruit harvested by pneumatic shakers comprised as much as 90% of the total, but less than that of hand-harvested fruit. The ergonomic analysis by electromyography showed that muscle strain in the back, shoulders, and forearms was low in workers operating the light-weight, pneumatic shakers that were tethered to the platform with a tool balancer. The new harvesting method can reduce the labor requirement to about 100 hour/hectare/year and help to mitigate the rising labor cost and shortage of workers for harvesting fresh-market quality blueberries.

Beschreibung: The perception and absorption of light by plants is a driving force in plant evolutionary history, as plants have evolved multiple photoreceptors to perceive different light attributes including duration, intensity, direction and quality. Plant photoreceptors interpret these signals from the light environment and mold plant architecture to maximize foliar light capture. As active sites of the production and accumulation of energy‐rich products, leaves are targets of pests and pathogens, which have driven the selection of physiological processes to protect these energy‐rich tissues. In the last ten years, several research groups have accumulated evidence showing that plant photoreceptors control specific molecular programs that define plant growth and immune processes. Here, we discuss recent knowledge addressing these roles in Arabidopsis and show that (1) plant immune responses affect energy acquisition and partitioning; (2) plant photoreceptors interpret the light environment and control growth and immune processes; and finally; (3) defense and light signaling pathways can be genetically manipulated to obtain plants able to grow and defend at the same time. This basic knowledge from Arabidopsis plants should lead new lines of applied research in crops.

Beschreibung: The population of Africa will double in the next 33 years to reach 2.5 billion by 2050. Although roughly 60% of the continent’s population is engaged in agriculture, the produce from this sector cannot feed its citizens. Hence, in 2013 alone, Africa imported 56.5 million tons of wheat, maize, and soybean at the cost of 18.8 billion USD. Although crops cultivated in Africa play a vital role in their contribution to Food Security, they produce inferior yields compared to those in other parts of the world. For instance, the average cereal yield in Africa is only 1.6 t·ha−1 compared to the global 3.9 t·ha−1. Low productivity in Africa is also related to poor soil fertility and scarce moisture, as well as a variety of insect pests, diseases, and weeds. While moisture scarcity is responsible for up to 60% of yield losses in some African staple cereals, insect pests inflict annually substantial crop losses. In order to devise a strategy towards boosting crop productivity on the continent where food insecurity is most prevalent, these production constraints should be investigated and properly addressed. This review focuses on conventional (also known as genetic) intensification in which crop productivity is raised through breeding for cultivars with high yield-potential and those that thrive well under diverse and extreme environmental conditions. Improved crop varieties alone do not boost crop productivity unless supplemented with optimum soil, water, and plant management practices as well as the promotion of policies pertaining to inputs, credit, extension, and marketing. Studies in Kenya and Uganda have shown that the yield of cassava can be increased by 140% in farmers’ fields using improved varieties and management practices. In addition to traditional organic and inorganic fertilizers, biochar and African Dark Earths have been found to improve soil properties and to enhance productivity, although their availability and affordability to African farmers remains to be explored. The concept of Integrated Soil Fertility Management (ISFM) has been successfully implemented in some African countries in the Great Lake Region. Other innovative technologies favorably accepted by farmers are the “Push-pull System” (an elegant method of controlling a devastating insect pest and a parasitic weed) and NERICA (New Rice for Africa, in which rice varieties with desirable nutritional and agronomic properties were developed by crossing Asian and African rice). This review calls for African governments and institutions not only to provide conducive environments but also to abide by the Maputo 2003 Declaration where they agreed to invest 10% of their national budget to agricultural research and development as the outcome has a positive impact on productivity and ultimately improves the livelihood of farmers.

Beschreibung: Plants are extremely versatile organisms that respond to the environment in which they find themselves, but a large part of their development is under genetic regulation. The links between developmental parameters and yield are poorly understood in oilseed rape; understanding this relationship will help growers to predict their yields more accurately and breeders to focus on traits that may lead to yield improvements. To determine the relationship between seed yield and other agronomic traits, we investigated the natural variation that already exists with regards to resource allocation in 37 lines of the crop species Brassica napus. Over 130 different traits were assessed; they included seed yield parameters, seed composition, leaf mineral analysis, rates of pod and leaf senescence and plant architecture traits. A stepwise regression analysis was used to model statistically the measured traits with seed yield per plant. Above-ground biomass and protein content together accounted for 94.36% of the recorded variation. The primary raceme area, which was highly correlated with yield parameters (0.65), provides an early indicator of potential yield. The pod and leaf photosynthetic and senescence parameters measured had only a limited influence on seed yield and were not correlated with each other, indicating that reproductive development is not necessarily driving the senescence process within field-grown B. napus. Assessing the diversity that exists within the B. napus gene pool has highlighted architectural, seed and mineral composition traits that should be targeted in breeding programmes through the development of linked markers to improve crop yields.

Beschreibung: Rice is the staple food for more than half of the world’s population. Although rice production has doubled in the last 30 years as a result of the development of high-yield, widely adaptable, resource-responsive, semi-dwarf varieties, the threat of a food crisis remains as severe as it was 60 years ago due to the ever-increasing population, water scarcity, labor scarcity, shifting climatic conditions, pest/diseases, loss of productive land to housing, industries, rising sea levels, increasing incidences of drought, flood, urbanization, soil erosion, reduction in soil nutrient status, and environmental issues associated with high-input agriculture. Among these, drought is predicted to be the most severe stress that reduces rice yield. Systematic research on drought over the last 10 years has been conducted across institutes on physiology, breeding, molecular genetics, biotechnology, and cellular and molecular biology. This has provided a better understanding of plant drought mechanisms and has helped scientists to devise better strategies to reduce rice yield losses under drought stress. These include the identification of quantitative trait loci (QTLs) for grain yield under drought as well as many agronomically important traits related to drought tolerance, marker-assisted pyramiding of genetic regions that increase yield under drought, development of efficient techniques for genetic transformation, complete sequencing and annotation of rice genomes, and synteny studies of rice and other cereal genomes. Conventional and marker-assisted breeding rice lines containing useful introgressed genes or loci have been field tested and released as varieties. Still, there is a long way to go towards developing drought-tolerant rice varieties by exploiting existing genetic diversity, identifying superior alleles for drought tolerance, understanding interactions among alleles for drought tolerance and their interaction with genetic backgrounds, and pyramiding the best combination of alleles.

Beschreibung: Napier grass (Pennisetum purpureum Schumach.) is a fast-growing perennial grass native to Sub-Saharan Africa that is widely grown across the tropical and subtropical regions of the world. It is a multipurpose forage crop, primarily used to feed cattle in cut and carry feeding systems. Characterization and diversity studies on a small collection of Napier grasses have identified a moderate level of genetic variation and highlighted the availability of some good agronomic traits, particularly high biomass production, as a forage crop. However, very little information exists on precise phenotyping, genotyping and the application of molecular technologies to Napier grass improvement using modern genomic tools which have been applied in advancing the selection and breeding of important food crops. In this review paper, existing information on genetic resources, molecular diversity, yield and nutritional quality of Napier grass will be discussed. Recent findings on characterizing disease resistance and abiotic stress (drought) tolerance will also be highlighted. Finally, opportunities and future prospects for better conservation and use arising from the application of modern genomic tools in Napier grass phenotyping and genotyping will be discussed.

Beschreibung: Agriculture is the largest user of world water resources, accounting for 70% of all consumption. Reducing water consumption and increasing water use efficiency in agriculture are two of the main challenges that need to be faced in the coming decades. Radicchio Rosso di Treviso Tardivo (RTT) is a vegetable that requires a water forcing process prior to final commercialization which presents a significant environmental impact due to the high water volumes used and then dispersed into the environment. The experiment was aimed at reducing the water use in the forcing process of RTT, by developing a pilot system with recycled water in a closed loop through ozone treatment. Concerning water quality, the redox potential value was higher in the ozonized system, whereas turbidity, pH and electrical conductivity of the ozonized system did not change significantly from the control. Yield and quality of plants obtained in the ozonized system did not significantly differ from the control plants except for the antioxidant activity that was higher in plants forced using the water treated with ozone. Our initial results suggest that the ozone treatment could be applied in the forcing process and is suitable for growers, saving up to 95% of water volumes normally used for this cultivation practice.

Beschreibung: Groundnut (Arachis hypogaea L.) genotypes were assessed for pod yield and physiological parameters under heat-stress and non-stress environments. The air temperatures under heat-stress environments were 35 °C and above during flowering, and below 35 °C in non-stress environments. Variability was significant for pod yield and physiological parameters among the genotypes under heat stress. A pod yield reduction of 1.5% to 43.2% was observed under heat-stress environments. However, in heat-tolerant genotypes, either stable or increased pod yield was recorded under high-temperature stress. GJG 31, ICGV 87846, ICGV 03057, ICGV 07038 and GG 20 showed an increase in pod yield by 9.0% to 47.0% at high temperatures, with a 0.65% to 3.6% increase in pod growth rate, while ICGV 06420, ICGV 87128, ICGV 97182, TCGS 1043 and ICGV 03042 are stable for pod yield and recorded a 0.25% to 3.1% increase in pod growth rate. Pod yield, hundred-seed weight, and pod growth rate under heat stress can be used as criteria for selection of heat stress tolerant-genotypes. Based on stress tolerance indices and pod yield performance, ICGVs 07246, 07012, 06039, 06040, 03042, 07038 and 06424 were identified as heat-tolerant genotypes.

Beschreibung: A field experiment was conducted at three locations in the southern region of Ethiopia during the 2012 and 2013 cropping seasons to evaluate chickpea cultivars for their response to soil zinc application, including agronomic performance, grain yield, grain zinc concentration, zinc and agronomic efficiency. Fifteen chickpea cultivars were evaluated in a randomized complete block design with three replications at each location and year. The highest number of pods (237) plant−1 was obtained from Butajira local landrace. The cultivar Naatolii produced the highest grain yield (2895 kg·ha−1), while the breeding line FLIP03-53C had the lowest yield (1700 kg·ha−1). The highest zinc concentrations of 47.5, 47.4, and 46.4 mg·kg−1 grain were obtained from the cultivar Arerti, and the two breeding lines FLIP07-27C and FLIP08-60C, respectively. The highest zinc efficiency (88%) was obtained from the Wolayita local landrace, whereas the highest agronomic efficiency of 68.4 kg yield increase kg−1 zinc application was obtained from the cultivar Naatolii. The current research identified chickpea cultivars with high grain zinc concentration, zinc efficiency, agronomic efficiency, and grain yield. The identification of cultivars with high grain zinc concentration allows the use of chickpea as a potential alternative to help to correct zinc deficiency, which is highly prevalent in the population of the region.

Beschreibung: Round-bale silage harvesting and processing methods were assessed to evaluate overwintering ability and dry matter (DM) yield, fermentation quality and palatability of overwintered dwarf Napiergrass (Pennisetum purpureum Schumach) in the two years following establishment in Nagasaki, Japan, in May 2013 using rooted tillers with a density of 2 plants/m2. In 2014, harvesting methods under no-wilting treatment were compared for flail-type harvesting with a round-baler (Flail/baler plot) and mower conditioning with a round-baler (Mower/baler plot), which is common for beef-calf–producing farmers in the region. In 2015, the effect of ensilage with wilting was investigated only in the Mower/baler plot. Dwarf Napiergrass was cut twice, in early August (summer) and late November (late autumn), each year. The winter survival rate was greater than 96% in May both years. The DM yield in the Mower/baler plot did not differ significantly for the first summer cutting or the annual total from the Flail/baler plot, but did show inferior yield for the second cutting. The fermentation quality of the second-cut plants, estimated using the V2-score, was higher in the Flail/baler plot than in the Mower/baler plot, possibly because of higher air-tightness, and the second-cut silage tended to have better fermentation quality than the first-cut silage in both harvesting plots. Wilting improved the fermentation quality of dwarf Napiergrass silage in summer, but not in autumn. The palatability of the silage, as estimated by alternative and voluntary intake trials using Japanese Black beef cattle, did not differ significantly between plots. The results suggest that dwarf Napiergrass can be better harvested using a mower conditioner with processing by a round-baler, an approach common to beef-calf–producing farmers, than with the flail/baler system, without reducing the persistence, yield, or palatability of the silage. Moreover, wilting treatment improved the fermentation quality of the dwarf Napiergrass silage when processed in summer.

Beschreibung: The combination of biochar (BC) with compost has been suggested to be a promising strategy to promote plant growth and performance, but although “synergistic” effects have been stated to occur, full-factorial experiments are few, and explicit tests for synergism are lacking. We tested the hypothesis that a combination of BC and spent mushroom substrate (SMS) has a positive synergistic effect on plant growth and physiological performance in a nutrient-limited growing media. A greenhouse experiment with a full factorial design was conducted using mixed-wood BC (3.0 kg·m−2) and SMS (1.5 kg·m−2) (the combination was not co-composted) as organic soil amendments for the annual Abutilon theophrasti and the perennial Salix purpurea. Several measurements related to plant growth and physiological performance were taken throughout the experiment. Contrary to the hypothesis, we found that the combination of BC + SMS had neutral or antagonistic interactive effects on many plant growth traits. Antagonistic effects were found on maximum leaf area, above- and belowground biomass, reproductive allocation, maximum plant height, chlorophyll fluorescence, and stomatal conductance of A. theophrasti. The effect on S. purpurea was mostly neutral. We conclude that the generalization that BC and compost have synergistic effects on plant performance is not supported.

Beschreibung: Remotely-sensed canopy temperature from infrared thermometer (IRT) sensors has long been shown to be effective for detecting plant water stress. A field study was conducted to investigate peach tree responses to deficit irrigation which was controlled using canopy to air temperature difference (ΔT) during the postharvest period at the USDA-ARS (U.S. Department of Agriculture, Agricultural Research Service) San Joaquin Valley Agricultural Sciences Center in Parlier, California, USA. The experimental site consisted of a 1.6 ha early maturing peach tree orchard. A total of 18 IRT sensors were used to control six irrigation treatments including furrow, micro-spray, and surface drip irrigation systems with and without postharvest deficit irrigation. During the postharvest period in the 2012–2013 and 2013–2014 growing seasons, ΔT threshold values at mid-day was tested to trigger irrigation in three irrigation systems. The results showed that mid-day stem water potentials (ψ) for well irrigated trees were maintained at a range of −0.5 to −1.2 MPa while ψ of deficit irrigated trees dropped to lower values. Soil water content in deficit surface drip irrigation treatment was higher compared to deficit furrow and micro-spray irrigation treatments in 2012. The number of fruits and fruit weight from peach trees under postharvest deficit irrigation treatment were less than those well-watered trees; however, no statistically significant (at the p 〈 0.05 level) reduction in fruit size or quality was found for trees irrigated by surface drip and micro-spray irrigation systems by deficit irrigation. Beside doubles, we found an increased number of fruits with deep sutures and dimples which may be a long-term (seven-year postharvest regulated deficit irrigation) impact of deficit irrigation on this peach tree variety. Overall, deployment of IRT sensors provided real-time measurement of canopy water status and the information is valuable for making irrigation management decisions.

Beschreibung: Brachiaria grass is an emerging forage option for livestock production in Kenya. Kenya lies within the center of diversity for Brachiaria species, thus a high genetic variation in natural populations of Brachiaria is expected. Overgrazing and clearing of natural vegetation for crop production and nonagricultural uses and climate change continue to threaten the natural biodiversity. In this study, we collected 79 Brachiaria ecotypes from different parts of Kenya and examined them for genetic variations and their relatedness with 8 commercial varieties. A total of 120 different alleles were detected by 22 markers in the 79 ecotypes. Markers were highly informative in differentiating ecotypes with average diversity and polymorphic information content of 0.623 and 0.583, respectively. Five subpopulations: International Livestock Research Institute (ILRI), Kitui, Kisii, Alupe, and Kiminini differed in sample size, number of alleles, number of private alleles, diversity index, and percentage polymorphic loci. The contribution of within‐the‐individual difference to total genetic variation of Kenyan ecotype population was 81%, and the fixation index (FST = 0.021) and number of migrant per generation (Nm = 11.58) showed low genetic differentiation among the populations. The genetic distance was highest between Alupe and Kisii populations (0.510) and the lowest between ILRI and Kiminini populations (0.307). The unweighted neighborjoining (NJ) tree showed test ecotypes grouped into three major clusters: ILRI ecotypes were present in all clusters; Kisii and Alupe ecotypes and improved varieties grouped in clusters I and II; and ecotypes from Kitui and Kiminini grouped in cluster I. This study confirms higher genetic diversity in Kenyan ecotypes than eight commercial varieties (Basilisk, Humidicola, Llanero, Marandú, MG4, Mulato II, Piatá and Xaraés) that represent three species and one three‐way cross‐hybrid Mulato II. There is a need for further collection of local ecotypes and their morphological, agronomical, and genetic characterizations to support Brachiaria grass breeding and conservation programs.

Beschreibung: Maize production in Uganda is constrained by various factors, but especially drought and stem borers contribute to significant yield losses. Genetically modified (GM) maize with increased drought tolerance and/or Bt insect resistance (producing the Bacillus thuringiensis Cry protein) is considered as an option. For an ex ante impact analysis of these technologies, a farmer survey was carried out in nine districts of Uganda, representing the major farming systems. The results showed that farmers did rate stem borer and drought as the main constraints for maize farming. Most farmers indicated a positive attitude towards GM maize, and 86% of all farmers said they would grow GM maize. Farmer estimated yield losses to drought and stem borer damage were on average 54.7% and 23.5%, respectively, if stress occurred. Taking the stress frequency into consideration (67% for both), estimated yield losses were 36.5% and 15.6% for drought and stem borer, respectively. According to the ex-ante partial budget analysis, Bt hybrid maize could be profitable, with an average value/cost ratio of 2.1. Drought tolerant hybrid maize had lower returns and a value/cost ratio of 1.5. Negative returns occurred mainly for farmers with non-stressed grain yields below 2 t·ha−1. The regulatory framework in Uganda needs to be finalized with consideration of strengthening key institutions in the maize sector for sustainable introduction of GM maize.

Beschreibung: Breeding of native cool-season grasses has the potential to improve forage production and expand the range of bioenergy feedstocks throughout western North America. Basin wildrye (Leymus cinereus) and creeping wildrye (Leymus triticoides) rank among the tallest and most rhizomatous grasses of this region, respectively. The objectives of this study were to develop interspecific creeping wildrye (CWR) × basin wildrye (BWR) hybrids and evaluate their biomass yield relative to tetraploid ‘Trailhead’, octoploid ‘Magnar’ and interploidy-hybrid ‘Continental’ BWR cultivars in comparison with other perennial grasses across diverse single-harvest dryland range sites and a two-harvest irrigated production system. Two half-sib hybrid populations were produced by harvesting seed from the tetraploid self-incompatible Acc:641.T CWR genet, which was clonally propagated by rhizomes into isolated hybridization blocks with two tetraploid BWR pollen parents: Acc:636 and ‘Trailhead’. Full-sib hybrid seed was also produced from a controlled cross of tetraploid ‘Rio’ CWR and ‘Trailhead’ BWR plants. In space-planted range plots, the ‘Rio’ CWR × ‘Trailhead’ BWR and Acc:641.T CWR × Acc:636 BWR hybrids displayed high-parent heterosis with 75% and 36% yield advantages, respectively, but the Acc:641.T CWR × ‘Trailhead’ BWR hybrid yielded significantly less than its BWR high-parent in this evaluation. Half-sib CWR × BWR hybrids of Acc:636 and ‘Trailhead’ both yielded as good as or better than available BWR cultivars, with yields similar to switchgrass (Panicum virgatum), in the irrigated sward plots. These results elucidate opportunity to harness genetic variation among native grass species for the development of forage and bioenergy feedstocks in western North America.

Beschreibung: Soil fertility is one of the major limiting factors for crop’s productivity in Egypt and the world in general. Biological nitrogen fixation (BNF) has a great importance as a non-polluting and a cost-effective way to improve soil fertility through supplying N to different agricultural systems. Faba bean (Vicia faba L.) is one of the most efficient nitrogen-fixing legumes that can meet all of their N needs through BNF. Therefore, understanding the impact of rhizobial inoculation and contrasting soil rhizobia on nodulation and N2 fixation in faba bean is crucial to optimize the crop yield, particularly under low fertility soil conditions. This study investigated the symbiotic effectiveness of 17 Rhizobium/Agrobacterium strains previously isolated from different Egyptian governorates in improving the nodulation and N2 fixation in faba bean cv. Giza 843 under controlled greenhouse conditions. Five strains that had a high nitrogen-fixing capacity under greenhouse conditions were subsequently tested in field trials as faba bean inoculants at Ismaillia Governorate in northeast Egypt in comparison with the chemical N-fertilization treatment (96 kg N·ha−1). A starter N-dose (48 kg N·ha−1) was applied in combination with different Rhizobium inoculants. The field experiments were established at sites without a background of inoculation under low fertility sandy soil conditions over two successive winter growing seasons, 2012/2013 and 2013/2014. Under greenhouse conditions, inoculated plants produced significantly higher nodules dry weight, plant biomass, and shoot N-uptake than non-inoculated ones. In the first season (2012/2013), inoculation of field-grown faba bean showed significant improvements in seed yield (3.73–4.36 ton·ha−1) and seed N-yield (138–153 Kg N·ha−1), which were higher than the uninoculated control (48 kg N·ha−1) that produced 2.97 Kg·ha−1 and 95 kg N·ha−1, respectively. Similarly, in the second season (2013/2014), inoculation significantly improved seed yield (3.16–4.68 ton·ha−1) and seed N-yield (98–155 Kg N·ha−1) relative to the uninoculated control (48 kg N·ha−1), which recorded 2.58 Kg·ha−1 and 80 kg N·ha−1, respectively. Interestingly, faba bean inoculated with strain Rlv NGB-FR 126 showed significant increments in seed yield (35%–48%) and seed N-yield (34%–49%) compared to the inorganic N fertilizers treatment (96 kg N·ha−1) over the two cropping seasons, respectively. These results indicate that inoculation of faba bean with effective rhizobial strains can reduce the need for inorganic N fertilization to achieve higher crop yield under low fertility soil conditions.

Beschreibung: In recent years, with climate change, drought stress has been witnessed in many parts of the world. In many irrigated regions also, shortage of water supply allows only limited irrigation. These conditions have an adverse effect on the productivity of many crops including cereals such as wheat. Therefore, genetics of drought/water stress tolerance in different crops has become a priority area of research. This research mainly involves use of quantitative trait locus (QTL) analysis (involving both interval mapping and association mapping) for traits that are related to water-use efficiency. In this article, we briefly review the available literature on QTL analyses in wheat for traits, which respond to drought/water stress. The outlook for future research in this area and the possible approaches for utilizing the available information on genetics of drought tolerance for wheat breeding are also discussed.

Beschreibung: n/a

Beschreibung: Phalaris aquatica is a cool-season perennial grass species that is extensively cultivated in Australia, with additional usage in other areas of the world. Phalaris displays a number of desirable agronomic characteristics, although unfavourable traits include excessive seed shattering, sensitivity to aluminium toxicity, and several toxicosis syndromes. Varietal development has to date been based on traditional selection methods, but would benefit from the application of genomics-based approaches, which require the development of large-scale sequence resources. Due to a large nuclear DNA content, methods that target the expressed component of the genome and reduce the complexity of analysis are most amenable to current sequencing technologies. A reference unigene set has been developed by transcriptome sequencing of multiple tissues from a single plant belonging to the variety Landmaster. Comparisons have been made to gene complements from related species, as well as reference protein databases, and patterns of gene expression in different tissues have been evaluated. A number of candidate genes relevant to removal of undesirable attributes have been identified. The reference unigene set will provide the basis for detailed studies of differential gene expression and identification of candidate genes for potential transgenic deployment, as well as a critical resource for genotypic analysis to support future genomics-assisted breeding activities for phalaris improvement.

Beschreibung: Because of continuing increases in atmospheric CO2, identifying cultivars of crops with larger yield increases at elevated CO2 may provide an avenue to increase crop yield potential in future climates. Free-air CO2 enrichment (FACE) systems have most often been used with multiple replications of each CO2 treatment in order to increase confidence in the effect of elevated CO2. For screening of cultivars for yield increases at elevated CO2, less precision about the CO2 effect, but more precision about cultivar ranking within CO2 treatments is appropriate. As a small-scale test of this approach, three plots, each of four cultivars of wheat, were grown in single FACE and control plots over two years, and the cultivar rankings of yield at elevated and ambient CO2 were compared. Each replicate plot was the size used in traditional cultivar comparisons. An additional test using four smaller replicate plots per cultivar within one FACE and one ambient plot was used to compare nine cultivars in another year. In all cases, elevated CO2 altered the ranking of cultivars for yield. This approach may provide a more efficient way to utilize FACE systems for the screening of CO2 responsiveness.

Beschreibung: In northern Europe, replacing winter barley with winter wheat as the preceding crop for winter oilseed rape (Brassica napus L.; WOSR) often results in a delayed WOSR sowing and poor autumn growth. Based on data from a field experiment running in 2009/2010, 2010/2011, and 2012/2013, this study aims (i) to investigate how a delayed sowing method affects seed yield, N offtake with the seeds, and apparent N use efficiency (NUE) of WOSR; (ii) to test the ability of autumn and spring N fertilization to compensate for the negative effects of a delayed sowing method; and (iii) to estimate the minimum autumnal growth for optimal seed yield. In order to create sufficiently differentiated canopies, a combination of four sowing methods (first week of August until the third week of September) and four autumn N treatments (0, 30, 60, and 90 kg·N·ha−1) was established. Each of these 16 different canopies was fertilized with 5 N amounts (0/0, 40/40, 80/80, 120/120, 140/140 kg·N·ha−1) in spring in order to estimate separate N response curves. Above-ground N accumulation in autumn and seed yield and N offtake by the seeds were determined. Plant establishment after mid-September significantly decreased seed yield. Autumn N fertilization of at least 30 kg·N·ha−1 increased seed yield and N offtake by the seeds without any significant interaction with sowing method and spring N supply. However, the pathway(s) remain(s) unclear. Spring N fertilization up to 130 kg·N·ha−1 (estimated by a Linear-Plateau N response curve) increased seed yield. NUE decreased with increasing N supply, where WOSR used autumn N to a lesser extent than spring N. An above-ground N uptake of at least 10–15 kg·N·ha−1 at the end of autumn growth was required to achieve high seed yields. From an environmental point of view, optimal autumn growth should be attained by choosing an adequate sowing method, not by applying additional N in autumn.

Beschreibung: Leaf senescence is a long developmental phase important for plant performance and nutrient management. Cell constituents are recycled in old leaves to provide nutrients that are redistributed to the sink organs. Up to now, metabolomic changes during leaf senescence have been mainly studied in Arabidopsis (Arabidopsis thaliana L.). The metabolite profiling conducted in barley (Hordeum vulgare L.) during primary leaf senescence under two nitrate regimes and in flag leaf shows that amino acids, hexose, sucrose and glycolysis intermediates decrease during senescence, while minor carbohydrates accumulate. Tricarboxylic acid (TCA) compounds changed with senescence only in primary leaves. The senescence-related metabolite changes in the flag leaf were globally similar to those observed in primary leaves. The effect of senescence on the metabolite changes of barley leaves was similar to that previously described in Arabidopsis except for sugars and glycolysis compounds. This suggests a different role of sugars in the control of leaf senescence in Arabidopsis and in barley.

Beschreibung: Forage legumes have a relatively high biomass yield and crude protein content, but their grazed and harvested biomass lacks the high-energy carbohydrates required to meet the productivity potential of modern livestock breeds. Because of their low carbohydrate content, forage legume diets are typically supplemented with starch rich cereal grains or maize (Zea mays), leading to the disruption of local nutrient cycles. Although plant leaves were first reported to accumulate starch in a diurnal pattern over a century ago, leaf starch content has yet to be exploited as an agronomic trait in forage crops. Forage legumes such as red clover (Trifolium pratense) have the genetic potential to accumulate up to one third of their leaf dry mass as starch, but this starch is typically degraded at night to support nighttime growth and respiration. Even when diurnal accumulation is considered with regard to the time the crop is harvested, only limited gains are realized due to environmental effects and post-harvest losses from respiration. Here we present original data for starch metabolism in red clover and place it in the broader context of other forage legumes such as, white clover (T. repens), and alfalfa (Medicago sativa). We review the application of recent advances in molecular breeding, plant biology, and crop phenotyping, to forage legumes to improve and exploit a potentially valuable trait for sustainable ruminant livestock production.

Beschreibung: Agronomy, Vol. 7, Pages 68: Performance of Precision Mobile Drip Irrigation in the Texas High Plains Region Agronomy doi: 10.3390/agronomy7040068 Authors: Susan A. O’Shaughnessy Paul D. Colaizzi Mobile drip irrigation (MDI) technology adapts driplines to the drop hoses of moving sprinkler systems to apply water as the drip lines are pulled across the field. There is interest in this technology among farmers in the Texas High Plains region to help sustain irrigated agriculture. However, information on the performance of this system and its benefits relative to common sprinkler application technologies in the region are limited. A two-year study was conducted in 2015 and 2016 to compare grain yields, crop water use (ETc) and water use efficiency (WUE) of corn (Zea Mays L.) irrigated with MDI, low elevation spray application (LESA) and low energy precision application (LEPA) methods. Irrigation amounts for each application method were based on weekly neutron probe readings. In both years, grain yield and yield components were similar among application treatment methods. Although WUE was similar for the MDI treatment plots compared with LEPA and LESA during the wet growing season (2015), MDI demonstrated improved WUE during the drier year of 2016. Additional studies using crops with less than full canopy cover at maturity (sorghum and cotton) are needed to document the performance of MDI in the Texas High Plains region.

Beschreibung: Agronomy, Vol. 7, Pages 82: Transferring a Biomass Enhancement Biotechnology from Glasshouse to Field: A Case Study on Wheat GWD RNAi Agronomy doi: 10.3390/agronomy7040082 Authors: Alex Whan Arunas Verbyla Jos Mieog Crispin Howitt Jean-Philippe Ral In glasshouse studies we have previously shown that endosperm-specific RNAi suppression of the primary starch phosphorylation enzyme, Glucan, Water Dikinase (GWD) leads to enhanced early vigor, greater leaf biomass, and increases in both head size and yield. To confirm these affects in a field setting, trials were conducted in three Australian environments. Field results were consistent with those in the glasshouse for increased flag leaf area and rachis nodes. However, there was also a decrease in tiller number and consequently a decrease in yield for one event at two sites. These findings provide potentially important information on plant vigor enhancement and highlight the challenges of transferring the modification of complex traits from single plants in controlled environments to the field.

Beschreibung: High value crop producers in California rely heavily on soil fumigation to control a wide array of soil borne pests including nematodes, pathogens and weeds. Fumigants with broad biocidal activity can affect soil microbial communities that contribute to nutrient cycling and plant nutrient uptake which can impact soil health. It is often thought that soil microbial communities make a relatively rapid recovery following fumigation. However, recently it has been found that repeated application of fumigants over time can have greater and longer lasting impacts on soil microorganisms than single fumigation events. Therefore, the main objective of this study was to determine the effect of long-term repeated application of fumigants on soil microbial communities and compare them with non-fumigated and organic sites. Soil samples were collected from fields in Watsonville, CA. Chronosequence sites were defined by number of years of annual fumigation (yaf) with methyl bromide (15, 26, 33, 39 yaf) at the time of sampling, and representative non-fumigated sites were also included for comparison. Phospholipid fatty acid (PLFA) analysis was used to analyze the samples. The canonical variate analysis showed that microbial communities in sites with a longer history of fumigation (33 and 39 yaf) were similar to one another; however, they differed significantly from 15 yaf site and further analysis concluded that non-fumigated sites were significantly different than fumigated sites. This study showed that the proportion of arbuscular mycorrhizal fungi (AMF) was lower in all fumigated (15, 33 and 39 yaf) sites as compared to their non-fumigated counterparts, which could be a threat to sustainability since AMF plays a major role in soil health and quality.

Beschreibung: Arbuscular mycorrhizal fungi (AMF) play major roles in nutrient acquisition by crops and are key actors of agroecosystems productivity. However, agricultural practices can have deleterious effects on plant–fungi symbiosis establishment in soils, thus inhibiting its potential benefits on plant growth and development. Therefore, we have studied the impact of different soil management techniques, including conventional moldboard ploughing and no-till under an optimal nitrogen (N) fertilization regime and in the absence of N fertilization, on AMF spore density and soil chemical, physical, and biological indicators in the top 20 cm of the soil horizon. A field experiment conducted over six years revealed that AMF spore density was significantly lower under conventional tillage (CT) combined with intensive synthetic N fertilization. Under no-till (NT) conditions, the density of AMF spore was at least two-fold higher, even under intensive N fertilization conditions. We also observed that there were positive correlations between spore density, soil dehydrogenase enzyme activity, and soil penetration resistance and negative correlations with soil phosphorus and mineral N contents. Therefore, soil dehydrogenase activity and soil penetration resistance can be considered as good indicators of soil quality in agrosystems. Furthermore, the high nitrate content of ploughed soils appears to be detrimental both for the dehydrogenase enzyme activity and the production of AMF spores. It can be concluded that no-till, by preventing soil from structural and chemical disturbances, is a farming system that preserves the entire fungal life cycle and as such the production of viable spores of AMF, even under intensive N fertilization.

Beschreibung: Agronomy, Vol. 7, Pages 83: Comprehensive Screening of Some West and Central African Sesame Genotypes for Drought Resistance Probing by Agromorphological, Physiological, Biochemical and Seed Quality Traits Agronomy doi: 10.3390/agronomy7040083 Authors: Komivi Dossa Louis Yehouessi Benoît Likeng-Li-Ngue Diaga Diouf Boshou Liao Xiurong Zhang Ndiaga Cissé Joseph Bell Sesame is an important crop in West and Central Africa playing a role of an alternative cash crop for smallholders. However, sesame productivity is highly impaired by drought. This study aimed at identifying some drought-resistant genotypes and efficient screening traits in large sesame germplasm. Ten genotypes were examined based on 21 biochemical, physiological, agromorphological and seed quality traits under three weeks of water stress. A high variability for drought resistance was observed among the genotypes. The genotypes WC17, WC18 and WC14 were drought resistant, WC12, WC13, WC06 and WC03 were moderately drought resistant while, WC02, WC10 and WC08 were drought sensitive, based on principal component analysis. The resistant genotypes exhibited both avoidance and tolerance features including increase of the root system, reduced water loss, highest activity of antioxidative enzymes and accumulation of proline. They produced higher biomass and had higher ability to maintain seed quality under drought stress compared with the sensitive genotypes. Strong accumulation (~200% ratio stress/control) of biochemical markers including superoxide dismutase, ascorbate peroxidase, catalase and proline could be regarded as an important indicator for selecting drought resistant genotypes. This study represents a reference for future research towards developing new varieties with improved drought resistance in West and Central Africa.

Beschreibung: Agronomy, Vol. 7, Pages 84: Straw Application Strategy to Optimize Nutrient Release in a Southeastern China Rice Cropland Agronomy doi: 10.3390/agronomy7040084 Authors: Weiqi Wang Jordi Sardans Chun Wang Ting Pan Congsheng Zeng Derrick Lai Mireia Bartrons Josep Peñuelas The management and improvement of paddy soils fertility are key factors for the future capacity of rice production. The return of rice straw to paddy soils is the best alternative to the application of industrial fertilizers for rice production sustainability. The best strategy for applying rice straw to improve soil nutritional capacity during rice growth has not yet been investigated. We compared straw decomposition in the ditches and ridges in paddy fields subjected to a typical crop management in southeastern China. Straw spread on the ridges provided lower residual straw carbon (C) concentration and mass, lower nitrogen:phosphorus ratio N:P, C:N, and C:P ratios, and lower soil salinity, as well as higher temperature, and higher N- and P-release capacity during the rice crop in comparison to the straw spread in the ditches. Therefore, applying rice straw to the ridges is better strategy than applying it to ditches to enhance rice production.

Beschreibung: Conservation agriculture (CA) can sustainably address soil degradation and improve crop yields. However, the success of CA amongst South African smallholder farmers is not known. The aims of the study were to find out: (1) the extent of CA practice by the Eastern Cape smallholder farmers; (2) perceptions towards CA amongst smallholder farmers with some history of practising the technology; and (3) the impact of practised CA components on soil quality indicators. Diagnostic survey techniques and soil sampling in farmers’ fields were employed to gather data from five districts of the Eastern Cape, South Africa. The most common CA principle adopted by surveyed farmers was no-till (34.81%), whilst crop rotation and residue retention were practised by only 25.93% and 22.22% of the farmers, respectively. Education level and CA training influenced the likelihood of a farmer to practise no-till farming, whilst the likelihood of farmers to retain residues was influenced by education level and access to grazing lands. Lack of appropriate equipment and costly herbicides were the major constraining factors to practising CA. Crop residue retention conflicted with the common practice of free-range livestock grazing. Cabbage, maize and beans were the most common crops of choice for the few farmers that practised crop rotations. No significant (p > 0.05) improvement on soil quality indicators was observed with CA compared to the conventional farming method. The noted high dependency on government grants by the smallholder farmers could be a disincentive towards the adoption of agricultural innovations such as CA. Identification of practical key CA entry points is recommended, bearing in mind the noted impediments to CA adoption.

Beschreibung: Vegetable sources and agro-industrial residues represent an important source of phenolic compounds that are useful in a wide range of applications, especially those with biological activities. Conventional techniques of phytochemical extraction have been associated with a high consumption of organic solvents that limits the application of bioactive extracts, leading to the implementation of novel extraction technologies using mechanisms such as Ultrasound Assisted Extraction (UAE). In the present review, an analysis of the involved variables in the extraction yield of phenolic compounds through UAE is presented, highlighting the advantages of this technology based on the results obtained in various optimized studies. A comparison with other technologies and a proposal of its possible application for agro industrial residues as raw material of phenolic compounds is also indicated. Finally, it is concluded that UAE is a technology that is placed within the area of Sustainable Chemistry since it promotes the use of renewable raw materials through the extraction of phenolic compounds, implementing the substitution of organic solvents with solvents that do not present toxic effects, lowering the energy consumption when compared to conventional methods and minimizing process times and temperatures, which is useful for the extraction of thermo-labile compounds.

Beschreibung: Several miRNAs are conserved in different plant families, but their abundance and target genes vary between species, organs, and stages of development. Target genes of miRNAs are mostly transcription factors, involved in the control of many plant developmental processes, including fruit development. MiR164 is a conserved miRNA, highly expressed in fruits, and is validated to target a subset of genes of the NAC-domain transcription factor gene family. The objective of this work was to analyze the phenotypic effects of the constitutive expression of miR164 during the life cycle of Arabidopsis and tomato. MiR164 overexpression (164-OE) lines for Arabidopsis and tomato were generated and analyzed during plant development. The constitutive miR164 expression showed that miR164 affected the morphology of Arabidopsis and tomato, and it affected the transition from the vegetative to the reproductive phase in Arabidopsis. Moreover, the miR164 overexpression affected the time required for each developmental stage of tomato fruit. These results suggest that miR164 plays general and specific roles during development in Arabidopsis and tomato, including fruit development, which could be exploited for the improvement of traits of agronomic interest in important species.

Beschreibung: Agronomy, Vol. 7, Pages 49: Impact of Different Agricultural Waste Biochars on Maize Biomass and Soil Water Content in a Brazilian Cerrado Arenosol Agronomy doi: 10.3390/agronomy7030049 Authors: Alicia Speratti Mark Johnson Heiriane Martins Sousa Gilmar Nunes Torres Eduardo Guimarães Couto Arenosols in the Brazilian Cerrado are increasingly being used for agricultural production, particularly maize. These sandy soils are characterized by low soil organic matter, low available nutrients, and poor water-holding capacity. For this reason, adding biochar as a soil amendment could lead to improved water and nutrient retention. A greenhouse experiment was carried out using twelve biochars derived from four feedstocks (cotton husks, swine manure, eucalyptus sawmill residue, sugarcane filtercake) pyrolized at 400, 500 and 600 °C and applied at 5% w/w. The biochars’ effect on maize biomass was examined, along with their contribution to soil physical properties including water retention, electrical conductivity (EC), and grain size distribution. After six weeks, maize plants in soils with eucalyptus and particularly filtercake biochar had higher biomass compared to those in soils with cotton and swine manure biochars. The latter’s low biomass was likely related to excessive salinity. In general, our biochars showed potential for increasing θ in sandy soils compared to the soil alone. Filtercake and eucalyptus biochars may improve soil aeration and water infiltration, while applying cotton and swine manure biochars at levels <5% to avoid high salinity could contribute to improved soil water retention in Cerrado Arenosols.

Beschreibung: In nature, plants integrate a wide range of light signals from solar radiation to adapt to the surrounding light environment, and these light signals also regulate a variety of important agronomic traits. Blue light-sensing cryptochrome (cry) and red/far-red light-sensing phytochrome (phy) play critical roles in regulating light-mediated physiological responses via the regulated transcriptional network. Accumulating evidence in the model plant Arabidopsis has revealed that crys and phys share two mechanistically distinct pathways to coordinately regulate transcriptional changes in response to light. First, crys and phys promote the accumulation of transcription factors that regulate photomorphogenesis, such as HY5 and HFR1, via the inactivation of the CONSTITUTIVE PHOTOMORPHOGENIC1/SUPPRESSOR OF PHYA-105 E3 ligase complex by light-dependent binding. Second, photoactive crys and phys directly interact with PHYTOCHROME INTERACTING FACTOR transcription factor family proteins to regulate transcriptional activity. The coordinated regulation of these two pathways (and others) by crys and phys allow plants to respond with plasticity to fluctuating light environments in nature.

Beschreibung: Heterogeneity in pineapple fruit quality explains the low export volume of fruits from Benin to international markets. This work aims to investigate the influences of residues mulching or burying and N-K fertilization on (1) fresh fruit juice quality and the proportion of fruit meeting European standards and (2) fruit acceptability for fresh local consumption, as well as to identify morphological characteristics most related to fruit chemical quality attributes. The experimental design was a split-plot with three replications, where the main factor was N-K fertilization (T1 = 1.6 N and 1.6 K, T2 = 5.8 N and 6.6 K, T3 = 10 N and 11.6 K, T4 = 1.6 N and 11.6 K, T5 = 10 N and 1.6 K in g·plant−1) and the sub-plot factor was mulching with pineapple residues (no mulching = 0, surface mulching = 10, buried = 10 in t·ha−1). The results suggested that residues mulching and N-K fertilization has improved the percentage of fruit meeting European standards and local acceptability. The treatments T2B (T2 + burying) and T4B (T4 + burying) gave a higher proportion of fruits meeting European standards and were also promising for producing highly acceptable fruits by local consumers. Finally, the results revealed that the ratios of crown length: fruit length, crown length: infructescence length and crown length: median diameter were significantly associated with fruit quality, which has not yet been reported.

Beschreibung: High molecular weight fructans are the main class of water-soluble carbohydrate used for energy storage in many temperate grass species including perennial ryegrass (Lolium perenne L.). As well as being important readily mobilisable energy reserves for the plant, fructans are also involved in stress tolerance. Fructans are also readily digested by grazing ruminants and hence are a valuable source of energy for sheep, beef and dairy production systems in temperate regions. This paper describes the re-programming of the expression of fructan biosynthesis genes through the transgenic manipulation of 6-glucose fructosyltransferase (6G-FFT) and sucrose:sucrose 1-fructosyl-transferase (1-SST) in perennial ryegrass. Transgenic events were developed with altered fructan accumulation patterns with increases in fructan accumulation and greatly increased accumulation of fructan in leaf blades as opposed to the traditional site of fructan accumulation in the pseudostem. This altered site of fructan accumulation has potential benefits for animal production as leaf blades form the major part of the diet of grazing ruminants. Some of the transgenic events also exhibited enhanced biomass production. This combination of high quality and enhanced yield is of great interest to forage plant breeders and whilst the expression of these phenotypes needs to be confirmed under field conditions, the identification and characterisation of the transgenic events described in this paper validate the potential for the manipulation of fructan biosynthesis in perennial ryegrass.

Beschreibung: This paper reviews the current status, methodology, achievements, and prospects of alfalfa (Medicago sativa L.) breeding in China. There are 77 cultivars that have been registered in the country, these include 36 cultivars bred through breeding programs, 17 introduced from overseas, 5 domesticated from wild ecotypes, and 19 through regional collection/breeding programs. Cultivars have been selected for cold resistance, disease resistance, salt tolerance, grazing tolerance, high yield, and early maturity. Most of these cultivars have been developed through conventional breeding techniques, such as selective and cross breeding, and some are now being evaluated that have been developed through the application of transgenic technology. The major problems for alfalfa breeding in China include low success rate, slow progress to breed resistant varieties, lack of breeding materials and their systematic collection, storage and evaluation, lack of advanced breeding techniques, and low adoption rate of new cultivars. There are gaps in alfalfa breeding between China and the developed world. Improvement of alfalfa breeding techniques, development of cultivars with adaptations to different regions within China, and the protection and utilization of alfalfa germplasm resources have been identified as major strategies to improve the efficiency of alfalfa breeding in China.

Beschreibung: A novel new way to achieve chemical-free defoliation of cotton is discussed. The research found that by severing the phloem tissue on the main stalk, via a girdling operation, the operation stimulated the cotton plant to alter its growth into an early senescence pathway that resulted in the plant shedding its leaves and opening up all its bolls, leaving the plant in the perfect state for machine harvesting. Even with follow-up rains, zero regrowth occurred in the treated plants, unlike the untreated control plots where significant regrowth did occur. This report compares the results of greenhouse and field trials where the girdling operation was performed by hand, flame, mechanical and via a CO2 laser to achieve phloem tissue severance. Design parameters for a prototype laser girdling system are also provided. Results suggest that for deficit irrigated cotton, girdling can provide an alternative means to defoliate cotton.

Beschreibung: Previous work has shown that a short non-saline sprinkling, following saline sprinkling, increased crop growth. We incorporated this finding into an investigation of two approaches to the conjunctive use of saline and non-saline water sources for sprinkler irrigation of potatoes viz., (i) mixing waters prior to application, and (ii) keeping waters temporally separate, that is commencing each irrigation with saline water and finishing it with non-saline sprinkling. The latter approach delayed canopy senescence and increased tuber weight by at least 150%. Under both approaches, soil salinities and leaf and tuber concentrations of Na+ and Cl− were similar. Thus, the advantages of a non-saline sprinkling cannot be explained in terms of its effect on either soil osmotic potential or bulk tissue concentrations of putatively toxic ions Na+ and Cl−. We propose that the positive effect of finishing irrigations with a non-saline sprinkling may be attributed to either dilution, and hence increase in osmotic potential, of the water film that remains on the leaf after each irrigation or its effect on the distribution of the putatively toxic ions Na+ and Cl− within tissue.

Beschreibung: Peat is used as rooting medium in greenhouse horticulture. Biochar is a sustainable alternative for the use of peat, which will reduce peat derived carbon dioxide emissions. Biochar in potting soil mixtures allegedly increases water storage, nutrient supply, microbial life and disease suppression but this depends on feedstock and the production process. The aim of this paper is to find combinations of feedstock and production circumstances which will deliver biochars with value for the horticultural end user. Low-temperature (600 °C–750 °C) gasification was used for combined energy and biochar generation. Biochars produced were screened in laboratory tests and selected biochars were used in plant experiments. Tests included dry bulk density, total pore space, specific surface area, phytotoxicity, pH, EC, moisture characteristics and microbial stability. We conclude that biochars from nutrient-rich feedstocks are too saline and too alkaline to be applied in horticultural rooting media. Biochars from less nutrient-rich feedstocks can be conveniently neutralized by mixing with acid peat. The influence of production parameters on specific surface area, pH, total pore space and toxicity is discussed. Biochar mildly improved the survival of beneficial micro-organisms in a mix with peat. Overall, wood biochar can replace at least 20% v/v of peat in potting soils without affecting plant growth.