Kriterien zur Stickstoffeffizienz moderner Winterweizensorten und deren Eignung für low-input Anbausysteme

Nitrogen deficiency is one of the most important reasons for reduced quality and yield stability in wheat production under low-input conditions. The present project intends to develop criteria allowing to find varieties that are adapted for low-input agricultural conditions. Therefore, yield and nitrogen uptake and use dynamics of eleven modern wheat varieties have been studied under low and high input conditions on a long term field experiment in Changins. This preliminary report shows that nitrogen efficiency defined as yield per available nitrogen is a useful criterion to distinguish nutrient efficiency under high nitrogen conditons but not when nitrogen is lacking. In further studies we will focus on backing quality as a potential indicator for nitrogen efficiency at low nitrogen conditions

Mapping of quantitative adult plant field resistance to leaf rust and stripe rust in two European winter wheat populations reveals co-location of three QTL conferring resistance to both rust pathogens

Key message We detected several, most likely novel QTL for adult plant resistance to rusts. Notably three QTL improved resistance to leaf rust and stripe rust simultaneously indicating broad spectrum resistance QTL. Abstract The rusts of wheat (Puccinia spp.) are destructive fungal wheat diseases. The deployment of resistant cultivars plays a central role in integrated rust disease management. Durability of resistance would be preferred, but is difficult to analyse. The Austrian winter wheat cultivar Capo was released in the 1989 and grown on a large acreage during more than two decades and maintained a good level of quantitative leaf rust and stripe rust resistance. Two bi-parental mapping populations: Capo × Arina and Capo × Furore were tested in multiple environments for severity of leaf rust and stripe rust at the adult plant stage in replicated field experiments. Quantitative trait loci associated with leaf rust and stripe rust severity were mapped using DArT and SSR markers. Five QTL were detected in multiple environments associated with resistance to leaf rust designated as QLr.ifa-2AL, QLr.ifa-2BL, QLr.ifa-2BS, QLr.ifa-3BS, and QLr.ifa-5BL, and five for resistance to stripe rust QYr.ifa-2AL, QYr.ifa-2BL, QYr.ifa-3AS, QYr.ifa-3BS, and QYr.ifa-5A. For all QTL apart from two (QYr.ifa-3AS, QLr.ifa-5BL) Capo contributed the resistance improving allele. The leaf rust and stripe rust resistance QTL on 2AL, 2BL and 3BS mapped to the same chromosome positions, indicating either closely linked genes or pleiotropic gene action. These three multiple disease resistance QTL (QLr.ifa-2AL/QYr.ifa-2AL, QLr.ifa.2BL/QYr.ifa-2BL, QLr.ifa-3BS/QYr.ifa.3BS) potentially contribute novel resistance sources for stripe rust and leaf rust. The long-lasting resistance of Capo apparently rests upon a combination of several genes. The described germplasm, QTL and markers are applicable for simultaneous resistance improvement against leaf rust and stripe rust. © 2014 The Author(s)

Cell culturability of Pseudomonas protegensCHA0 depends on soil pH

Pseudomonas inoculants may lose colony-forming ability in soil, but soil properties involved are poorly documented. Here, we tested the hypothesis that soil acidity could reduce persistence and cell culturability of Pseudomonas protegensCHA0. At 1 week in vitro, strain CHA0 was found as culturable cells at pH 7, whereas most cells at pH 4 and all cells at pH 3 were noncultured. In 21 natural soils of contrasted pH, cell culturability loss of P. protegensCHA0 took place in all six very acidic soils (pH < 5.0) and in three of five acidic soils (5.0 < pH < 6.5), whereas it was negligible in the neutral and alkaline soils at 2 weeks and 2 months. No correlation was found between total cell counts of P. protegensCHA0 and soil composition data, whereas colony counts of the strain correlated with soil pH. Maintenance of cell culturability in soils coincided with a reduction in inoculant cell size. Some of the noncultured CHA0 cells were nutrient responsive in Kogure's viability test, both in vitro and in soil. Thus, this shows for the first time that the sole intrinsic soil composition factor triggering cell culturability loss in P. protegensCHA0 is soil acidit

Performance of eleven winter wheat varieties in a long term experiment on mineral nitrogen and organic fertilisation

There is an increasing awareness about the need for improving nitrogen use efficiency in crop production in order to meet economic and ecological standards. The present work provides insight into the varietal factors of wheat that determine nitrogen use in the plant. The performance of eleven winter wheat varieties in terms of grain yield and nitrogen uptake and use efficiency was tested within the framework of a 40-year long term field experiment of organic enrichment and mineral nitrogen fertilisation treatments. Globally, organic enrichment had a beneficial effect on the yield and grain nitrogen concentration and showed a strong interaction with the amount of applied mineral nitrogen fertiliser. Manure application generally had positive effects on varietal performances mainly due to indirect longterm effects on the soil properties. Varieties showed a broad range of responses to the treatments of the long term experiment, revealing significant genotype × environment interactions. Nevertheless, the varieties which performed well at high input levels were also the best at low input levels, suggesting that the genotype × environment interactions were not strong enough to inverse the performance ranking.Similarly, the varietal traits associated with high yielding or grain nitrogen concentration in high input conditions were the same as those identified under low input conditions. To conclude, these results suggest that the selection of wheat for nitrogen efficiency is possible under any nitrogen fertilisation regime.However, to be adapted to low input or organic agriculture, varieties also need traits other than nutrientuse efficiency, for example, disease resistance, resilience to abiotic stresses and competitiveness against weeds

Relationships Between Root Pathogen Resistance, Abundance and Expression of \u3ci\u3ePseudomonas\u3c/i\u3e Antimicrobial Genes, and Soil Properties in Representative Swiss Agricultural Soils

Strains of Pseudomonas that produce antimicrobial metabolites and control soilborne plant diseases have often been isolated from soils defined as disease-suppressive, i.e., soils, in which specific plant pathogens are present, but plants show no or reduced disease symptoms. Moreover, it is assumed that pseudomonads producing antimicrobial compounds such as 2,4-diacetylphloroglucinol (DAPG) or phenazines (PHZ) contribute to the specific disease resistance of suppressive soils. However, pseudomonads producing antimicrobial metabolites are also present in soils that are conducive to disease. Currently, it is still unknown whether and to which extent the abundance of antimicrobials-producing pseudomonads is related to the general disease resistance of common agricultural soils. Moreover, virtually nothing is known about the conditions under which pseudomonads express antimicrobial genes in agricultural field soils. We present here results of the first side-by-side comparison of 10 representative Swiss agricultural soils with a cereal-oriented cropping history for (i) the resistance against two soilborne pathogens, (ii) the abundance of Pseudomonas bacteria harboring genes involved in the biosynthesis of the antimicrobials DAPG, PHZ, and pyrrolnitrin on roots of wheat, and (iii) the ability to support the expression of these genes on the roots. Our study revealed that the level of soil disease resistance strongly depends on the type of pathogen, e.g., soils that are highly resistant to Gaeumannomyces tritici often are highly susceptible to Pythium ultimum and vice versa. There was no significant correlation between the disease resistance of the soils, the abundance of Pseudomonas bacteria carrying DAPG, PHZ, and pyrrolnitrin biosynthetic genes, and the ability of the soils to support the expression of the antimicrobial genes. Correlation analyses indicated that certain soil factors such as silt, clay, and some macro- and micronutrients influence both the abundance and the expression of the antimicrobial genes. Taken together, the results of this study suggests that pseudomonads producing DAPG, PHZ, or pyrrolnitrin are present and abundant in Swiss agricultural soils and that the soils support the expression of the respective biosynthetic genes in these bacteria to various degrees. The precise role that these pseudomonads play in the general disease resistance of the investigated agricultural soils remains elusive

Plant secondary metabolite-dependent plant-soil feedbacks can improve crop yield in the field.

Plant secondary metabolites that are released into the rhizosphere alter biotic and abiotic soil properties, which in turn affect the performance of other plants. How this type of plant-soil feedback affects agricultural productivity and food quality in the field in the context of crop rotations is unknown. Here, we assessed the performance, yield and food quality of three winter wheat varieties growing in field plots whose soils had been conditioned by either wild type or benzoxazinoid-deficient bx1 maize mutant plants. Following maize cultivation, we detected benzoxazinoid-dependent chemical and microbial fingerprints in the soil. The benzoxazinoid fingerprint was still visible during wheat growth, but the microbial fingerprint was no longer detected. Wheat emergence, tillering, growth, and biomass increased in wild type conditioned soils compared to bx1 mutant conditioned soils. Weed cover was similar between soil conditioning treatments, but insect herbivore abundance decreased in benzoxazinoid-conditioned soils. Wheat yield was increased by over 4% without a reduction in grain quality in benzoxazinoid-conditioned soils. This improvement was directly associated with increased germination and tillering. Taken together, our experiments provide evidence that soil conditioning by plant secondary metabolite producing plants can increase yield via plant-soil feedbacks under agronomically realistic conditions. If this phenomenon holds true across different soils and environments, optimizing root exudation chemistry could be a powerful, genetically tractable strategy to enhance crop yields without additional inputs

Factors of wheat grain resistance to Fusarium head blight

Fusarium head blight (FHB), caused by Fusarium graminearum, is an important wheat disease that affects grain yield and conformation, and contaminates grains with mycotoxins, including the trichothecene deoxynivalenol (DON). The impacts of Fusarium infections on grain filling, grain deformation and rheological properties were assessed under different environmental conditions. Genotypes with elevated grain anthocyanin content were used. Resistance of seven wheat varieties and breeding lines was assessed with artificial infections in the field. Grains from infected and control plots were assessed for proportion of Fusarium damaged kernels, grain filling (thousand kernel weight) and DON accumulation. Biochemical and rheological properties of harvested grain were also assessed. Grain resistance to Fusarium has several components, including resistance against DON accumulation, deformation and stability of grain filling. These mechanisms are interdependent but act independently. Resistance against DON contamination was highly influenced by environmental conditions, but environment had little effect on the other resistance components. Anthocyanins and protein concentrations were unchanged in infected grains, suggesting that FHB does not affect grain biosynthesis processes but impacts the transport of assimilates caused by changes in grain composition. We suggest that this is the reason for the alterations of rheological properties. The greater the grain resistance, the less was the impact on dough properties. This study suggests that the resilience of rheological properties under FHB infection pressure is an additional component of grain resistance to the disease

High-resolution analysis of a QTL for resistance to Stagonospora nodorum glume blotch in wheat reveals presence of two distinct resistance loci in the target interval

Stagonospora nodorum glume blotch (SNG), caused by the necrotrophic fungus Stagonospora nodorum, is one of the economically important diseases of bread wheat (Triticum aestivum L.). Resistance to SNG is known to be quantitative and previous studies of a recombinant inbred line (RIL) population identified a major quantitative trait locus (QTL) for resistance to SNG on the short arm of chromosome 3B. To localize this QTL (QSng.sfr-3BS) with high resolution, we constructed a genetic map for the QTL target region using information from sequenced flow-sorted chromosomes 3B of the two parental cultivars ‘Arina' and ‘Forno', the physical map of chromosome 3B of cultivar ‘Chinese Spring' and BAC-clone sequences. The mapping population of near-isogenic lines (NIL) was evaluated for SNG resistance in field infection tests. NILs segregated for disease resistance as well as for plant height; additionally, we observed a high environmental influence on the trait. Our analysis detected a strong negative correlation of SNG resistance and plant height. Further analysis of the target region identified two linked loci associated with SNG resistance. One of them was also associated with plant height, revealing an effect of QSng.sfr-3BS on plant height that was hidden in the RIL population. This result demonstrates an unexpectedly high genetic complexity of resistance controlled by QSng.sfr-3BS and shows the importance of the study of QTL in mendelized form in NILs

Lessons From 20 Years of Studies of Wheat Genotypes in Multiple Environments and Under Contrasting Production Systems

Identifying opportunities and limitations for closing yield gaps is essential for setting right the efforts dedicated to improve germplasm and agronomic practices. This study analyses genotypes × environments interaction (G × E), genetic progress, and grain yield stability under contrasting production systems. For this, we analyzed datasets obtained from three Swiss trial-networks of winter wheat that were designed to evaluate genotypes under organic farming conditions, conventional management with low-inputs (150 kg nitrogen (N) ha−1 with no fungicide application) and conventional management with high-inputs (170 kg N ha−1 with fungicide application). The datasets covered the periods from 1998 to 2018 for organic and conventional management with low-inputs and from 2008 to 2018 for conventional management with high-inputs. The trial-networks evaluated each year an average of 36 winter wheat genotypes that included released varieties, advanced breeding lines, and lines for registration and post-registration in Switzerland. We investigated within each trial-network the influence of years, genotypes, environments and their interactions on the total variance in grain yield and grain N concentration using variance components analyses. We further applied mixed models with regression features to dissect genetic components due to breeding efforts from non-genetic components. The genotype as a single factor or as a factor interacting with the environment or the year (G × E, G × year, and G × E × year) explained 13% (organic), 20% (conventional low-inputs), and 24% (conventional high-inputs) of the variance in grain yield, while the corresponding values for grain N concentration were 29%, 25%, and 32%. Grain yield has stagnated since 1990 for conventional systems while the trend under organic management was slightly negative. The dissection of a genetic component from the grain yield trends under conventional management showed that genetic improvements contributed with 0.58 and 0.68 t ha−1 y−1 with low- and high- inputs, respectively. In contrast, a significant genetic source in the grain yield trend under organic management was not detected. Therefore, breeding efforts have been less effective on the wheat productivity for organic farming conditions than for conventional ones