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Anthropogenic nitrogen inputs cause major negative environmental impacts, including emissions of the important greenhouse gas N2O. Despite their importance, shifts in terrestrial N loss pathways driven by global change are highly uncertain. Here we present a coupled soil-atmosphere isotope model (IsoTONE) to quantify terrestrial N losses and N2O emission factors from 1850-2020. We find that N inputs from atmospheric deposition caused 51% of anthropogenic N2O emissions from soils in 2020. The mean effective global emission factor for N2O was 4.3 ± 0.3% in 2020 (weighted by N inputs), much higher than the surface area-weighted mean (1.1 ± 0.1%). Climate change and spatial redistribution of fertilisation N inputs have driven an increase in global emission factor over the past century, which accounts for 18% of the anthropogenic soil flux in 2020. Predicted increases in fertilisation in emerging economies will accelerate N2O-driven climate warming in coming decades, unless targeted mitigation measures are introduced., Nature Communications, 13 (1), ISSN:2041-1723

Risk models for decisions on fungicide use based on weather data, disease monitoring, and control thresholds are used as important elements in a sustainable cropping system. The need for control of leaf blotch diseases in wheat (caused by Zymoseptoria tritici, Parastagonospora nodorum and Pyrenophora tritici-repentis) vary significantly across years and locations. Disease development is mainly driven by humidity events during stem elongation and heading. Two risk models were tested in field trials in order to identify situations favourable for the development of leaf blotch diseases in Lithuania, Norway, Sweden, Finland and Denmark. The Crop Protection Online (CPO) model uses days with precipitation (>1 mm), while the humidity model (HM) uses 20 continuous hours with relative humidity (RH) ≥ 85% as criteria for the need of a fungicide application. Forty-seven field trials were carried out during two seasons to validate these two risk-models against reference fungicide treatments. The season 2018 was dry and 2019 had an average precipitation profile. The two risk models with few exceptions provided acceptable disease control. In 2018, very few treatments were recommended by the models, saving 85–98% of treatments compared to the reference treatments, while in the wetter season 2019, 31% fewer applications were recommended. Based on specific criteria including fungicide input and net yield responses the models gave correct recommendations in 95% of the trials in 2018 and in 54–58% of the trials in 2019 compared with reference treatments dominated by 2–3 sprays. In comparison with single spray references, the models gave correct recommendations in 54–69% of the situations.

The use of disease-free seeds or bulbs is very crucial to ensure sustainable and profitable agricultural pro-duction. Seed-borne pathogens which are responsible for significant yield losses in various crops need to be successfully eliminated with appropriate seed treatments. In this study, we investigated the efficacy of gaseous ozone (O3) and ozonated water treatments on the inactivation of seed-borne fungal and bacterial pathogens of widely cultivated vegetable and cereal seeds, and ornamental bulbs. We demonstrated that O3 application to tomato and cucumber seeds inactivates Fusarium oxysporum f. sp. lycopersici, Fusarium oxysporum f. sp. radicis-lycopersici, Clavibacter michiganensis subsp. michiganensis, Pseuodomonas syringae pv. tomato, and Pseudomonas syringae pv. lachrymans, respectively, with no negative effect on seed ger-mination rate. The sterilization capacity of O3 has substantially increased when the seeds were soaked in water before the treatments. The saprophytic fungal load and the infection rate of Pectobacterium caro-tovorum subsp. carotovorum on several species and cultivars of ornamental bulbs were suppressed by O3 treatment. A strong decrease in the infection rate of Tilletia caries was also shown in O3-treated wheat seeds under field conditions. Overall, the current study indicated that O3 treatment has great potential in ensuring the use of disease-free seeds or other propagation materials, which is indispensable at the beginning of crop production.(c) 2022 The Author(s). Published by Elsevier B.V. on behalf of King Saud University. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/)., Scientific and Technological Research Council of Turkey; [108O380], Funding This work was supported by the Scientific and Technological Research Council of Turkey [Grant No 108O380] .

Pre-anthesis drought is expected to greatly increase yield losses in wheat (Triticum aestivum L.), one of the most important crops worldwide. Most studies investigate the effects of pre-anthesis drought only at maturity. The physiology of the plant before anthesis and how it is affected during drought is less studied. Our study focused on physiological patterns in wheat plants during pre- and post-anthesis drought. To this end, we measured leaf xylem water potential, osmotic potential and water content in different plant parts at a high temporal frequency: every 3 days, three times a day. The experiment started just before booting until 2 weeks after flowering. Drought stress was induced by withholding irrigation with rewatering upon turgor loss, which occurred once before and once after anthesis. The goal was to investigate the patterns of osmotic adjustment, when it is used for protection against drought, and if the strategy changes during the phenological development of the plant. Our data gave no indication of daily osmotic adjustment, but did show a delicate control of the osmotic potential during drought in both leaves and stem. Under high drought stress, osmotic potential decreased to avoid further water loss. Before anthesis, rewatering restored leaf water potential and osmotic potential quickly. After anthesis, rewatering restored water potential in the flag leaves, but the osmotic potential in the stem and flag leaf remained low longer. Osmotic adjustment was thus maintained longer after anthesis, showing that the plants invest more energy in the osmotic adjustment after anthesis than before anthesis. We hypothesize that this is because the plants consider the developing ear after anthesis a more important carbohydrate sink than the stem, which is a carbohydrate sink before anthesis, to be used later as a reserve. Low osmotic potential in the stem allowed turgor maintenance, while the low osmotic potential in the flag leaf led to an increase in leaf turgor beyond the level of the control plants. This allowed leaf functioning under drought and assured that water was redirected to the flag leaf and not used to refill the stem storage.

Breeding of multi-resistant varieties to reduce yield loss due to disease damage and lodging, and reduction of input intensity are of high importance for a more sustainable cereal production. The aim of this study was to evaluate (i) yield reduction caused by diseases and lodging and (ii) impact of input intensity and soil fertility in cereal variety trials grown under two intensities. Intensity 2 was treated with and intensity 1 without fungicides and growth regulators. We applied multiple regression approaches based on mixed linear models. First, we estimated relative yield reduction in intensity 1 compared to intensity 2 as a function of severity scores of diseases and lodging. High yield reductions occurred in winter wheat and winter triticale, moderate in winter rye and winter barley and low in spring barley. The damage potential was highest for yellow rust, followed by brown rust, lodging and Septoria tritici blotch. Medium damage potential was identified for dwarf leaf rust and low for powdery mildew, Septoria nodorum blotch, Rhynchosporium as well as for stem and ear buckling. Second, differences in input intensity did not affect yield in intensity 2 across the range of nitrogen and fungicide application rates while higher yield occurred at higher growth regulator rates and soil fertility. Growth regulator was strongly related with higher yield in winter rye and winter barley, however in spring barley, a negative relation was found. Soil fertility showed the strongest yield impact in all crops.

International audience; The Nitrogen Use Efficiency (NUE) of grain cereals depends on nitrate (NO3-) uptake from the soil, translocation to the aerial parts, nitrogen (N) assimilation and remobilization to the grains. Brachypodium distachyon has been proposed as a model species to identify the molecular players and mechanisms that affects these processes, for the improvement of temperate C3 cereals. We report on the developmental, physiological and grain-characteristic responses of the Bd21-3 accession of Brachypodium to variations in NO3- availability. As previously described in wheat and barley, we show that vegetative growth, shoot/root ratio, tiller formation, spike development, tissue NO3- and N contents, grain number per plant, grain yield and grain N content are sensitive to pre- and/or post-anthesis NO3- supply. We subsequently described constitutive and NO3--inducible components of both High and Low Affinity Transport Systems (HATS and LATS) for root NO3- uptake, and BdNRT2/3 candidate genes potentially involved in the HATS. Taken together, our data validate Brachypodium Bd21-3 as a model to decipher cereal N nutrition. Apparent specificities such as high grain N content, strong post-anthesis NO3- uptake and efficient constitutive HATS, further identify Brachypodium as a direct source of knowledge for crop improvement.

Made available in DSpace on 2019-09-12T16:53:36Z (GMT). No. of bitstreams: 0 Previous issue date: 2019 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) In tropical biomes, abrupt cold events frequently occur in subtropical regions and can be associated with large daily thermal fluctuations. The bromeliad Nidularium minutum Mez is a cold tolerant species from the Atlantic Rainforest, which grows in the subtropical latitude, where temperatures range from 2 to 30 degrees C. We hypothesized that N. minutum plants would implement rapid metabolic adjustments to ensure survival during sudden cold events that occur in seasons other than winter. N. minutum plants were cultivated at 10 degrees C. Under this condition, there was an observed increase in soluble sugar content and nitric oxide (NO) emission, as well as a high nitrate reductase (NR) activity observed within the 72 h of cold exposure, when compared with plants maintained at 25 degrees C. These responses coincided with a decrease in antioxidant activity and an increase in lipid peroxidation (LPO). After 72 h of cold exposure, a subset of plants were de-acclimated at 25 degrees C. These plants displayed reduced soluble sugar concentrations, NO emissions, NR activity and LPO. Additionally, there was an increase in anti-oxidant activity, which indicated that the plants were recovering from cold stress. Furthermore, it was found that plants maintained at 10 degrees C for 168 h acclimated to the cold by reducing the NO content and maintaining the increased sugar concentrations, thus resulting in a less intense stress response. We conclude that rapid changes in NO content, sugar concentrations and antioxidant activity are metabolic adjustments that occur during the acclimation and de-acclimation processes of this bromeliad to low temperatures. During abrupt thermal changes in subtropical regions, such adjustments could enhance cold tolerance and increase the chances of survival for this plant. [Carvalho, Camila Pereira; Nievola, Catarina Carvalho] Inst Bot SMA SP, Nucleo Pesquisa Plantas Ornamentals, Ave Miguel Stefano 3687, BR-04301902 Sao Paulo, SP, Brazil [Cardoso-Gustayson, Poliana] Univ Fed ABC, Ctr Ciencias Nat & Humans, BR-09606070 Sao Bernardo Do Campo, Brazil [Rodrigues, Edson] Universidade de Taubaté (Unitau), Inst Basico Biociencias, BR-12030180 Taubate, SP, Brazil [Braga, Marcia Regina] Inst Botan SMA SP, Nucleo Pesquisa Fisiol & Bioquim, BR-04301902 Sao Paulo, SP, Brazil [Mercier, Helenice] Univ Sao Paulo, Inst Biociencias, Dept Bot, BR-05508090 Sao Paulo, SP, Brazil

Soils with high stone content represent a challenge to root development, as each stone is an obstacle to root growth. A high stone content also affects soil properties such as temperature or water content, which in turn affects root growth. We investigated the effects of all soil properties combined on root development in the field using both experiments and modeling. Field experiments were carried out in rhizotron facilities during two consecutive growing seasons (wheat [Triticum aestivum L.] and maize [Zea mays L.]) in silty loam soils with high (>50%) and low (

Organic dryland winter wheat (Triticum aestivum) growers in the U.S. are faced with high interannual variability in yields. This is related to the low annual precipitation and low soil fertility on the cultivated soils. Improving soil health is the key to increasing and maintaining crop yields. In this study, we compared the effects of different rates (0, 12.5, 25 and 50 Mg DW ha-1 compost and 2 Mg ha manure-1) of large quantities of steer manure compost and the inclusion of cover crops versus fallow on soil health and on carbon and phosphorus dynamics in two organic dryland systems with varying soil characteristics and microclimatic conditions. The two sites are located in Snowville and Blue Creek, Utah. At Snowville, the soil fertility is extremely low, pH is 8.5, and average total annual precipitation is 290 mm. At Blue Creek, the soil is more fertile, pH is 7.2 and average total annual precipitation is 485 mm. The results showed that the compost effect on measured physical, biological and chemical soil health indices (soil moisture, dehydrogenase and phosphatasesenzyme activities, soil organic carbon, Olsen P) were greater than the effects of cover crops at both sites. Differences were also found in phosphorus cycling between the two sites, with potential long-term impacts in soils with extreme low fertility due to lower rate of nutrient mineralization. By applying large quantities of compost (25-50 Mg DW ha-1) once, organic dryland winter wheat farmers can improve soil health, enhance SOM associated water retention and availability, and provide an environment for continuous sustainable wheat yield.

International audience; Agricultural crop residues represent a significant part of the biomass potentially available for renewable energy systems. Sustaining soil organic carbon (C) is a common limiting factor applied to the biophysically available resource to determine crop residues potential for bioenergy. Studies quantifying this potential have so far largely considered crop biomass to produce renewable energy as being independent from the energy conversion pathway. However, the conversion method has great influence on how much C in crop residues can be returned back and retained in soils. Here, we applied the C-TOOL soil C model for two extreme conversion pathways of agricultural straw management in terms of C returned back to soils, using Denmark as a case study. Those were anaerobic digestion, involving the return of recalcitrant C to fields, and combustion, involving no C returns to agricultural fields. Danish agriculture was represented by six different soil-cropping schemes units on which our two extreme bioenergy pathways were modelled. We applied a premise that for a given geographical unit, the same long-term soil C level needs to be achieved under these extreme bioenergy scenarios; therefore, we identified how much straw could be removed from agricultural fields in each case while maintaining equal soil organic carbon (SOC) levels. We found that at the scale of the whole country, only 26% of the straw potential can be harvested for use in combustion to maintain in average long-term SOC at the same level as it would have been with the anaerobic digestion scenario. Thus, consideration for the biomass conversion pathway is important when identifying agricultural residue potentials for energy conversion while ensuring that SOC level is not compromised.

There is an urgent need among plant breeders for a deeper understanding of the links between wheat genotypes and their ability to utilize light for biomass production and their efficiency at converting the biomass into grain yield. This field trail was conducted to investigate the variations in radiation use efficiency (RUE) and harvest index (HI) of four spring wheat cultivars grown on two soil types with two nitrogen (N) fertilization levels. Grain yield (GY) was significantly higher with 200 kg N ha&minus, 1 than 100 kg N ha&minus, 1 and on clay soil than on sandy soil, and a similar trend was observed for shoot dry matter (DM) at maturity. RUE and HI was neither affected by cultivar nor N-fertilization, but was affected by soil type, with a significantly higher RUE and HI on clay than on sandy soil. The differences of water holding capacity between the two soil types was suggested to be a major factor influencing RUE and HI as exemplified by the principal component analysis. Thus, to achieve a high RUE and/or HI, sustaining a good soil water status during the critical growth stages of wheat crops is essential, especially on sandy soils with a low water holding capacity.

Timely diagnosis of sugar beet above-ground biomass (AGB) is critical for the prediction of yield and optimal precision crop management. This study established an optimal quantitative prediction model of AGB of sugar beet by using hyperspectral data. Three experiment campaigns in 2014, 2015 and 2018 were conducted to collect ground-based hyperspectral data at three different growth stages, across different sites, for different cultivars and nitrogen (N) application rates. A competitive adaptive reweighted sampling (CARS) algorithm was applied to select the most sensitive wavelengths to AGB. This was followed by developing a novel modified differential evolution grey wolf optimization algorithm (MDE−GWO) by introducing differential evolution algorithm (DE) and dynamic non-linear convergence factor to grey wolf optimization algorithm (GWO) to optimize the parameters c and γ of a support vector machine (SVM) model for the prediction of AGB. The prediction performance of SVM models under the three GWO, DE−GWO and MDE−GWO optimization methods for CARS selected wavelengths and whole spectral data was examined. Results showed that CARS resulted in a huge wavelength reduction of 97.4% for the rapid growth stage of leaf cluster, 97.2% for the sugar growth stage and 97.4% for the sugar accumulation stage. Models resulted after CARS wavelength selection were found to be more accurate than models developed using the entire spectral data. The best prediction accuracy was achieved after the MDE−GWO optimization of SVM model parameters for the prediction of AGB in sugar beet, independent of growing stage, years, sites and cultivars. The best coefficient of determination (R2), root mean square error (RMSE) and residual prediction deviation (RPD) ranged, respectively, from 0.74 to 0.80, 46.17 to 65.68 g/m2 and 1.42 to 1.97 for the rapid growth stage of leaf cluster, 0.78 to 0.80, 30.16 to 37.03 g/m2 and 1.69 to 2.03 for the sugar growth stage, and 0.69 to 0.74, 40.17 to 104.08 g/m2 and 1.61 to 1.95 for the sugar accumulation stage. It can be concluded that the methodology proposed can be implemented for the prediction of AGB of sugar beet using proximal hyperspectral sensors under a wide range of environmental conditions.

The development and validation of hydroecological land-surface models to simulate agricultural areas require extensive data on weather, soil properties, agricultural management, and vegetation states and fluxes. However, these comprehensive data are rarely available since measurement, quality control, documentation, and compilation of the different data types are costly in terms of time and money. Here, we present a comprehensive dataset, which was collected at four agricultural sites within the Rur catchment in western Germany in the framework of the Transregional Collaborative Research Centre 32 (TR32) “Patterns in Soil–Vegetation–Atmosphere Systems: Monitoring, Modeling and Data Assimilation”. Vegetation-related data comprise fresh and dry biomass (green and brown, predominantly per organ), plant height, green and brown leaf area index, phenological development state, nitrogen and carbon content (overall > 17 000 entries), and masses of harvest residues and regrowth of vegetation after harvest or before planting of the main crop (> 250 entries). Vegetation data including LAI were collected in frequencies of 1 to 3 weeks in the years 2015 until 2017, mostly during overflights of the Sentinel 1 and Radarsat 2 satellites. In addition, fluxes of carbon, energy, and water (> 180 000 half-hourly records) measured using the eddy covariance technique are included. Three flux time series have simultaneous data from two different heights. Data on agricultural management include sowing and harvest dates as well as information on cultivation, fertilization, and agrochemicals (27 management periods). The dataset also includes gap-filled weather data (> 200 000 hourly records) and soil parameters (particle size distributions, carbon and nitrogen content; > 800 records). These data can also be useful for development and validation of remote-sensing products. The dataset is hosted at the TR32 database (https://www.tr32db.uni-koeln.de/data.php?dataID=1889, last access: 29 September 2020) and has the DOI https://doi.org/10.5880/TR32DB.39 (Reichenau et al., 2020).

Stomatal regulation and whole plant hydraulic signaling affect water fluxes and stress in plants. Land surface models and crop models use a coupled photosynthesis–stomatal conductance modeling approach. Those models estimate the effect of soil water stress on stomatal conductance directly from soil water content or soil hydraulic potential without explicit representation of hydraulic signals between the soil and stomata. In order to explicitly represent stomatal regulation by soil water status as a function of the hydraulic signal and its relation to the whole plant hydraulic conductance, we coupled the crop model LINTULCC2 and the root growth model SLIMROOT with Couvreur's root water uptake model (RWU) and the HILLFLOW soil water balance model. Since plant hydraulic conductance depends on the plant development, this model coupling represents a two-way coupling between growth and plant hydraulics. To evaluate the advantage of considering plant hydraulic conductance and hydraulic signaling, we compared the performance of this newly coupled model with another commonly used approach that relates root water uptake and plant stress directly to the root zone water hydraulic potential (HILLFLOW with Feddes' RWU model). Simulations were compared with gas flux measurements and crop growth data from a wheat crop grown under three water supply regimes (sheltered, rainfed, and irrigated) and two soil types (stony and silty) in western Germany in 2016. The two models showed a relatively similar performance in the simulation of dry matter, leaf area index (LAI), root growth, RWU, gross assimilation rate, and soil water content. The Feddes model predicts more stress and less growth in the silty soil than in the stony soil, which is opposite to the observed growth. The Couvreur model better represents the difference in growth between the two soils and the different treatments. The newly coupled model (HILLFLOW–Couvreur's RWU–SLIMROOT–LINTULCC2) was also able to simulate the dynamics and magnitude of whole plant hydraulic conductance over the growing season. This demonstrates the importance of two-way feedbacks between growth and root water uptake for predicting the crop response to different soil water conditions in different soils. Our results suggest that a better representation of the effects of soil characteristics on root growth is needed for reliable estimations of root hydraulic conductance and gas fluxes, particularly in heterogeneous fields. The newly coupled soil–plant model marks a promising approach but requires further testing for other scenarios regarding crops, soil, and climate.

Carbon exchange over croplands plays an important role in the European carbon cycle over daily to seasonal time scales. A better description of this exchange in terrestrial biosphere models-most of which currently treat crops as unmanaged grasslands-is needed to improve atmospheric CO2 simulations. In the framework we present here, we model gross European cropland CO2 fluxes with a crop growth model constrained by grain yield observations. Our approach follows a two-step procedure. In the first step, we calculate day-to-day crop carbon fluxes and pools with the WOrld FOod STudies (WOFOST) model. A scaling factor of crop growth is optimized regionally by minimizing the final grain carbon pool difference to crop yield observations from the Statistical Office of the European Union. In a second step, we re-run our WOFOST model for the full European 25 x 25 km gridded domain using the optimized scaling factors. We combine our optimized crop CO2 fluxes with a simple soil respiration model to obtain the net cropland CO2 exchange. We assess our model's ability to represent cropland CO2 exchange using 40 years of observations at seven European FluxNet sites and compare it with carbon fluxes produced by a typical terrestrial biosphere model. We conclude that our new model framework provides a more realistic and strongly observation-driven estimate of carbon exchange over European croplands. Its products will be made available to the scientific community through the ICOS Carbon Portal and serve as a new cropland component in the CarbonTracker Europe inverse model.

International audience; Climate change is increasing crop losses and yield variability with impacts for global food security. In this context, conservation agriculture appears as a potential solution to maintain crop productivity, soil fertility and environmental sustainability. Therefore, understanding the combined effects of soil tillage and crop succession over a long period is of primary interest. In this study, we analyzed data from a 50 year long-term field experiment to assess (i) the change of climatic parameters, wheat yield and soil organic carbon (SOC) content; (ii) the combined effects of crop succession (monoculture vs. crop rotation) and soil tillage system (minimum tillage vs. plough) on wheat yield, SOC content and other soil properties at three soil depths (0-10, 10-20 and 20-50 cm); and (iii) the relative contributions of climatic parameters, wheat phenology and agricultural practices on wheat yield variability. Wheat yield was 16% higher in crop rotation compared to monoculture, while soil tillage system had no significant effect on wheat yield during the period 1977-2016. Despite a SOC content decline over time, which was especially marked during the first ten years of the study, SOC content was 7% higher in the minimum tillage treatment compared to the plough treatment, while crop rotation had no significant effect. In 2016, after 50 years of experimentation, both crop succession and soil tillage systems influenced soil properties. Over the 50-year period, the climatic conditions around the heading phase explained 22% of yield variability, while 18% of this variability was explained by crop succession and 6% by the growing degree days until heading stage. In a context of conservation agriculture promotion, our long-term field experiment provides key evidence that the combination of both minimum soil tillage and crop rotation improves soil fertility and crop productivity.

Ammonia (NH3) emission from agriculture is an environmental threat and a loss of nitrogen for crop production. Mineral fertilizers and manure are significant sources of NH3, therefore, abatement technologies have been introduced to mitigate these emissions. The aim of this study was to demonstrate that low-cost measuring techniques are suitable to assess NH3 emissions in smaller plots, appropriate to test different managements. Two experiments were established to quantify NH3 emissions from urea application in a multi-plot design with radii of 5 (R5) and 20 m (R20). Field was bare soil partially surrounded by shelterbelts. Measurement techniques included passive flux samplers (Leuning), and passive concentration samplers (ALPHA) coupled to WindTrax dispersion model. NH3 emission from R5 was consistent with the emission from R20 when the surface-to-atmosphere exchange was not affected by shelterbelts, and wind speed near surface was greater than 1 m s&minus, 1. Both measurement methods gave unreliable NH3 quantification in combination with wind speed lower than 1 m s&minus, 1 and low emission strength. Cumulative emission over 60 h was 2% of the supplied N from the plots not affected by the shelterbelt, and 1% from the plots affected by shelterbelts, indicating that these structures can significantly reduce NH3 emissions.

In recent decades, remote sensing has increasingly been used to estimate the spatio-temporal evolution of crop biophysical parameters such as the above-ground biomass (AGB). On a local scale, the advent of unmanned aerial vehicles (UAVs) seems to be a promising trade-off between satellite/airborne and terrestrial remote sensing. This study aims to evaluate the potential of a low-cost UAV RGB solution to predict the final AGB of Zea mays. Besides evaluating the interest of 3D data and multitemporality, our study aims to answer operational questions such as when one should plan a combination of two UAV flights for AGB modeling. In this case, study, final AGB prediction model performance reached 0.55 (R-square) using only UAV information and 0.8 (R-square) when combining UAV information from a single flight with a single-field AGB measurement. The adding of UAV height information to the model improves the quality of the AGB prediction. Performing two flights provides almost systematically an improvement in AGB prediction ability in comparison to most single flights. Our study provides clear insight about how we can counter the low spectral resolution of consumer-grade RGB cameras using height information and multitemporality. Our results highlight the importance of the height information which can be derived from UAV data on one hand, and on the other hand, the lower relative importance of RGB spectral information.

Stevia rebaudiana Bertoni is a sweet medicinal herb that is cultivated worldwide. This study aimed to identify the genotypic responses and function of nine cultivars of S. rebaudiana (accession numbers 1-9 from the EUSTAS Stevia Gene Bank) to low temperature. Plants were grown in vitro and incubated under controlled conditions at 5° or 25°C for 1 month. Cold stress significantly decreased the maximum quantum yield of photosystem II (Fv/Fm) in all cultivars, which was more pronounced in cultivars 5, 6, 8, and 9. The efficiency of photosystems I and II (PIABS) also declined in cold-stressed plants and was accompanied by reductions in net photosynthesis (PN), intercellular CO2 (Ci), water use efficiency (WUE), and chlorophyll a, chlorophyll b and carotenoid contents, more so in cultivars 5, 6, 8, and 9. Regardless of the downregulation of photosynthetic capacity, the cold stress increased water-soluble carbohydrates in all cultivars, which was accompanied by an increase in fresh leaf mass and area, more so in cultivars 5, 6, 8, and 9. Furthermore, cold stress increased the stomatal index and density, epidermal cell density, stem diameter, xylem vessel width, phloem tissue width, and number of sclerenchyma in all cultivars. Even though the nine cultivars of S. rebaudiana had lower PSII efficiencies at low temperatures, the increase in carbohydrates and leaf mass suggests that damage to PSII is not responsible for the reduction in its efficiency. ispartof: FRONTIERS IN PLANT SCIENCE vol:9 ispartof: location:Switzerland status: published

In the Mediterranean, durum wheat is one of the major crops, but a high variability of grain yield and protein concentration (GPC) prevents an adequate agronomic planning at the farm or consortium level. Although there are many studies on monitoring of crop production and early prediction of yields, little has been done at the local scale. The aim of this study was to assess simplified integration algorithms (SIAs) for integrating remote sensing information with a crop model, to forecast the GPC and grain yield at the field scale. To this end, the CERES-Wheat model was run to simulate the seasonal average of grain yield (AVE) and GPC in Val d’ Orcia (Tuscany Region, Italy) during the 2009–2010 and 2010–2011 growing seasons. The performances of different vegetation indices from MODIS imagery in harvest forecasting were assessed and compared. The SIA formulation was based on the simulated AVE and GPC, and on their spatialization in relation to the intraannual variability between the fields described by vegetation indices. The simulated AVE traced the observed trend. The fraction of absorbed photosynthetically active radiation (fPAR) was the best index in describing grain yield, and the related SIA showed at validation good performance at the field scale (r² = 0.74). Conversely, the SIA was unable to predict GPC due to the low performance of CERES-Wheat in capturing the interannual variability and to the failure of the fPAR in describing the GPC interfields variability at intermediate canopy reflectance values.

Carbon exchange over croplands plays an important role in the European carbon cycle over daily to seasonal time scales. A better description of this exchange in terrestrial biosphere models-most of which currently treat crops as unmanaged grasslands-is needed to improve atmospheric CO2 simulations. In the framework we present here, we model gross European cropland CO2 fluxes with a crop growth model constrained by grain yield observations. Our approach follows a two-step procedure. In the first step, we calculate day-to-day crop carbon fluxes and pools with the WOrld FOod STudies (WOFOST) model. A scaling factor of crop growth is optimized regionally by minimizing the final grain carbon pool difference to crop yield observations from the Statistical Office of the European Union. In a second step, we re-run our WOFOST model for the full European 25 x 25 km gridded domain using the optimized scaling factors. We combine our optimized crop CO2 fluxes with a simple soil respiration model to obtain the net cropland CO2 exchange. We assess our model's ability to represent cropland CO2 exchange using 40 years of observations at seven European FluxNet sites and compare it with carbon fluxes produced by a typical terrestrial biosphere model. We conclude that our new model framework provides a more realistic and strongly observation-driven estimate of carbon exchange over European croplands. Its products will be made available to the scientific community through the ICOS Carbon Portal and serve as a new cropland component in the CarbonTracker Europe inverse model.

International audience; Scenario analysis constitutes a useful approach to synthesize knowledge and derive hypotheses in the case of complex systems that are documented with mainly qualitative or very diverse information. In this article, a framework for scenario analysis is designed and then, applied to global wheat health within a timeframe from today to 2050. Scenario analysis entails the choice of settings, the definition of scenarios of change, and the analysis of outcomes of these scenarios in the chosen settings. Three idealized agrosystems, representing a large fraction of the global diversity of wheat-based agrosystems, are considered, which represent the settings of the analysis. Several components of global changes are considered in their consequences on global wheat health: climate change and climate variability, nitrogen fertilizer use, tillage, crop rotation, pesticide use, and the deployment of host plant resistances. Each idealized agrosystem is associated with a scenario of change that considers first, a production situation and its dynamics, and second, the impacts of the evolving production situation on the evolution of crop health. Crop health is represented by six functional groups of wheat pathogens: the pathogens associated with Fusarium head blight; biotrophic fungi, Septoria-like fungi, necrotrophic fungi, soilborne pathogens, and insect-transmitted viruses. The analysis of scenario outcomes is conducted along a risk-analytical pattern, which involves risk probabilities represented by categorized probability levels of disease epidemics, and risk magnitudes represented by categorized levels of crop losses resulting from these levels of epidemics within each production situation. The results from this scenario analysis suggest an overall increase of risk probabilities and magnitudes in the three idealized agrosystems. Changes in risk probability or magnitude however vary with the agrosystem and the functional groups of pathogens. We discuss the effects of global changes on the six functional groups, in terms of their epidemiology and of the crop losses they cause. Scenario analysis enables qualitative analysis of complex systems, such as plant pathosystems that are evolving in response to global changes, including climate change and technology shifts. It also provides a useful framework for quantitative simulation modeling analysis for plant disease epidemiology.

International audience; Organic farming is often advocated as an approach to mitigate biodiversity loss on agricultural land. The phyllosphere provides a habitat for diverse fungal communities that are important for plant health and productivity. However, it is still unknown how organic farming affects the diversity of phyllosphere fungi in major crops. We sampled wheat leaves from 22 organically and conventionally cultivated fields in Sweden, paired based on their geographical location and wheat cultivar. Fungal communities were described using amplicon sequencing and real-time PCR. Species richness was higher on wheat leaves from organically managed fields, with a mean of 54 operational taxonomic units (OTUs) compared with 40 OTUs for conventionally managed fields. The main components of the fungal community were similar throughout the 350-km-long sampling area, and seven OTUs were present in all fields : Zymoseptoria, Dioszegia fristingensis, Cladosporium, Dioszegia hungarica, Cryptococcus, Ascochyta and Dioszegia. Fungal abundance was highly variable between fields, 10(3)-10(5) internal transcribed spacer copies per ng wheat DNA, but did not differ between cropping systems. Further analyses showed that weed biomass was the strongest explanatory variable for fungal community composition and OTU richness. These findings help provide a more comprehensive understanding of the effect of organic farming on the diversity of organism groups in different habitats within the agroecosystem.

International audience; Wheat being staple food of Pakistan is constantly attacked by major wheat aphid species, Schizaphis graminum (R.), Rhopalosiphum padi (L.) and Sitobion avenae (F.). Due to concern on synthetic chemical use in wheat, it is imperative to search for alternative environment-and human-friendly control measures such as botanical pesticides. In the present study, we evaluated the comparative role of neem seed extract (NSE), moringa leaf extract (MLE) and imidacloprid (I) in the management of the aphid as well as the yield losses parameters in late planted wheat fields. Imidacloprid reduced significantly aphids infestation compared to the other treatments, hence resulting in higher yield, particularly when applied with MLE. The percentages of yield increase in I+MLE treated plots over the control were 19.15-81.89% for grains per spike, 5.33-37.62% for thousand grain weight and 27.59-61.12% for yield kg/ha. NSE was the second most effective control measure in suppressing aphid population, but the yield protected by NSE treatment over the control was comparable to that by imidacloprid. Population densities of coccinellids and syrphids in the plots treated with NSE-2 were higher than those treated with imidacloprid in two out of three experiments during 2013-14. Low predator density in imidacloprid-treated plots was attributed to the lower availability of prey aphids. The efficacy of NSE against aphids varied depending on degree of synchronization among the application timing, the activity of aphids, crop variety and environmental conditions. Despite that, we suggested NSE to be a promising alternative botanical insecticide compared to the most commonly recommended imidiacloprid. Further studies should consider the side effects of biopesticides on non-target organisms in order to provide better management practices in the field.

International audience; Weed dynamics models are needed to design innovative weed management strategies. Here, we developed a 3D individual-based model called FLORSYS predicting growth and development of annual weeds and crops as a function of daily weather and cropping practices: (1) crop emergence is driven by temperature, and emerged plants are placed onto the 3D field map, depending on sowing pattern, density, and emergence rate; plants are described as cylinders with their leaf area distributed according to height; (2) weed emergence is predicted by an existing submodel, emerged weed seedlings are placed randomly; (3) plant phenology depends on temperature; (4) a previously developed submodel predicts available light in each voxel of the canopy; after emergence, plant growth is driven by temperature; when shaded, biomass accumulation results from the difference between photosynthesis and respiration; shading causes etiolation; (5) frost reduces biomass and destroys plants, (6) at plant maturity, the newly produced seeds are added to the soil seed bank. The model was used to test different sowing scenarios in an oilseed rape/winter wheat/winter barley rotation with sixteen weed annuals, showing that (1) crop yield loss was negatively correlated to weed biomass averaged over the cropping season; (2) weed biomass was decreased by scenarios allowing early and homogenous crop canopy closure (e.g. reduced interrows, increased sowing density, associated or undersown crops), increased summer fatal weed seed germination (e.g. delayed sowing) or, to a lesser degree, cleaner fields at cash crop sowing (e.g. sowing a temporary cover crop for "catching" nitrogen); (3) the scenario effect depended on weed species (e.g. climbing species were little affected by increased crop competition), and the result thus varied with the initial weed community (e.g. communities dominated by small weed species were hindered by the faster emergence of broadcast-sown crops whereas taller species profited by the more frequent gap canopies); (4) the effect on weed biomass of sowing scenarios applied to one year was still visible up to ten years later, and the beneficial effect during the test year could be followed by detrimental effects later (e.g. the changed tillage dates accompanying catch crops reduced weed emergence in the immediately following cash crop but increased seed survival and thus infestation of the subsequent crops). This simulation showed FLORSYS to predict realistic potential crop yields, and the simulated impact of crop scenarios was consistent with literature reports. (C) 2013 Elsevier B.V. All rights reserved.

This work is a detailed study of the infection of fungal biotrophic pathogens causing powdery mildew diseases on introgression lines originating from the intergeneric hybridisation between wheat and barley (Triticum aestivum L. × Hordeum vulgare L.). Powdery mildew fungi are among the most widespread biotrophic pathogens of plants also and infect dicot and monocot species. Most powdery mildew species are strictly host specific. They colonize only a narrow range of species or one particular host species. The intergeneric hybridisation between wheat and barley could result in expansions of host ranges of the barley powdery mildew. Our experiments covered natural infections in the field and artificial infections under greenhouse conditions. Formae speciales of powdery mildew were identified on the basis of the sequencing results of ribosomal internal transcribed spacer sequences (rDNA-ITS). We identified Blumeria graminis f.sp. tritici isolate 14 (HM484334) on the wheat parent and all wheat-barley introgression lines and B. g. f. sp. hordei isolate MUMH1723 (AB 273556) on the barley parent, respectively. The wheat-barley introgression lines were inoculated with barley powdery mildew under greenhouse conditions. According to our results the added barley chromosomes (or segments) do not cause host range expansion of barley powdery mildew.

To determine if present commercial broccoli cultivars meet the diverse needs of organic management systems, such as adaptation to low N input, mechanical weed management, and no chemical pesticide use, and to propose the selection environments for crop improve- ment for organic production, we compared hor- ticultural trait performance of 23 broccoli cul- tivars (G) under two management (M) systems (organic and conventional) in two regions of the United States (Oregon and Maine), includ- ing spring and fall trials. In our trials, location and season had the largest effect on broccoli head weight, with Oregon outperforming Maine, and fall trials outperforming spring plantings. M main effects and G × M interactions were often small, but G × M × E (location and sea- son) were large. Cultivars with both greater head weight and stability under conventional condi- tions generally had high head weight and stabil- ity under organic growing conditions, although there were exceptions in cultivar rank between management systems. Larger genotypic vari- ances and somewhat increased error variances observed in organic compared with conven- tional management systems led to repeatability for head weight and other horticultural traits that were similar or even higher in organic compared with conventional conditions. The ratio of cor- related response (predicting performance under organic conditions when evaluated in conven- tional conditions) to direct response (predicted performance in organic when evaluated under organic conditions) for all traits was close to but less than 1.0 with the exception of bead unifor- mity. This would imply that in most cases, direct selection in an organic environment could result in a more rapid genetic gain than indirect selec- tion in a conventional environment.

The aim of this study was to evaluate the performance of two predictive models for deoxynivalenol contamination of wheat at harvest in the Netherlands, including the use of weather forecast data and external model validation. Data were collected in a different year and from different wheat fields than data used for model development. The two models were run for six preset scenarios, varying in the period for which weather forecast data were used, from zero-day (historical data only) to a 13-day period around wheat flowering. Model predictions using forecast weather data were compared to those using historical data. Furthermore, model predictions using historical weather data were evaluated against observed deoxynivalenol contamination of the wheat fields. Results showed that the use of weather forecast data rather than observed data only slightly influenced model predictions. The percent of correct model predictions, given a threshold of 1,250 µg/kg (legal limit in European Union), was about 95% for the two models. However, only three samples had a deoxynivalenol concentration above this threshold, and the models were not able to predict these samples correctly. It was concluded that two- week weather forecast data can reliable be used in descriptive models for deoxynivalenol contamination of wheat, resulting in more timely model predictions. The two models are able to predict lower deoxynivalenol contamination correctly, but model performance in situations with high deoxynivalenol contamination needs to be further validated. This will need years with conducive environmental conditions for deoxynivalenol contamination of wheat.

The mycotoxin deoxynivalenol (DON), produced by several Fusarium spp., acts as a virulence factor and is essential for symptom development after initial wheat infection. Accumulating evidence shows that the production of this secondary metabolite can be triggered by diverse environmental and cellular signals, implying that it might have additional roles during the life cycle of the fungus. Here, we review data that position DON in the saprophytic fitness of Fusarium, in defense and in the primary C and N metabolism of the plant and the fungus. We combine the available information in speculative models on the role of DON throughout the interaction with the host, providing working hypotheses that await experimental validation. We also highlight the possible impact of control measures in the field on DON production and summarize the influence of abiotic factors during processing and storage of food and feed matrices. Altogether, we can conclude that DON is a very important compound for Fusarium to cope with a changing environment and to assure its growth, survival, and production of toxic metabolites in diverse situations.

During the past 50 years, China has successfully realized food self-sufficiency for its rapidly growing population. Currently, it feeds 22% of the global population with 9% of the global area of arable land. However, these achievements were made at high external resource use and environmental costs. The challenge facing China is to further increase food production while drastically decreasing the environmental costs of food production. Here we review the major developments in nutrient management in China over the last 50 years. We briefly analyze the current organizational structure of the “advisory system” in agriculture, the developments in nutrient management for crop production, and the developments in nutrient management in animal production. We then discuss the nutrient management challenges for the next decades, considering nutrient management in the whole chain of crop production–animal production–food processing–food consumption by households. We argue that more coherent national policies and institutional structures are required for research extension education to be able to address the immense challenges ahead. Key actions include nutrient management in the whole food chain concomitant with a shift in objectives from food security only to food security, resource use efficiency, and environmental sustainability; improved animal waste management based on coupled animal production and crop production systems; and much greater emphasis on technology transfer from science to practice through education, training, demonstration, and extension services.

International audience; Triticale and wheat are similar crops, but triticale represents a valuable alternative to wheat due to its greater biomass production and grain yield in Mediterranean-type growing conditions. However, despite the higher yield potential and increasing importance of this crop, there are no dynamic crop models available to assist triticale adaptation via simulation experiments. In a previous study, the APSIM-Nwheat model was parameterized for triticale resulting in a new APSIM-Triticale model but the new model was never compared with detailed experimental triticale data in a one-to-one comparison. Here, the new model was tested with detailed field experimental observations. APSIM-Triticale was able to reproduce phenology, biomass, grain yields and soil water dynamics. The model performed well over several years and management options that included different sowing densities, sowing dates and a short and tall cultivar. The tested model was then used to explore management options to maximize triticale yield across the Mediterranean Basin. The response to sowing density was cultivar and rainfall-environment dependent. The simulation analysis indicated that there was no yield advantage with higher sowing densities with a tall cultivar type in high yielding environments, despite its higher biomass growth rates. The highest yields were achieved at the early sowing date at the sowing densities between 100 and 300 plants/m(2) in the high rainfall regions for both short and the tall cultivars. The simulation study suggests that sowing a short cultivar with a reduced radiation use efficiency but early vigour growth could increase current yields across different regions, seasons and management options in the Mediterranean climate. (C) 2013 Elsevier B.V. All rights reserved.

Background In wheat, the vernalization requirement is mainly controlled by the VRN genes. Different species of hexaploid and tetraploid wheat are widely used as genetic source for new mutant variants and alleles for fundamental investigations and practical breeding programs. In this study, VRN-A1 and VRN-B1 were analysed for 178 accessions representing six tetraploid wheat species (Triticum dicoccoides, T. dicoccum, T. turgidum, T. polonicum, T. carthlicum, T. durum) and five hexaploid species (T. compactum, T. sphaerococcum, T. spelta, T. macha, T. vavilovii). Results Novel allelic variants in the promoter region of VRN-A1 and VRN-B1 were identified based on the change in curvature and flexibility of the DNA molecules. The new variants of VRN-A1 (designated as Vrn-A1a.2, Vrn-A1b.2 – Vrn-A1b.6 and Vrn-A1i) were found to be widely distributed in hexaploid and tetraploid wheat, and in fact were predominant over the known VRN-A1 alleles. The greatest diversity of the new variants of VRN-B1 (designated as VRN-B1.f, VRN-B1.s and VRN-B1.m) was found in the tetraploid and some hexaploid wheat species. For the first time, minor differences within the sequence motif known as the VRN-box of VRN1 were correlated with wheat growth habit. Thus, vrn-A1b.3 and vrn-A1b.4 were revealed in winter wheat in contrast to Vrn-A1b.2, Vrn-A1b.5, Vrn-A1b.6 and Vrn-A1i. It was found that single nucleotide mutation in the VRN-box can influence the vernalization requirement and growth habit of wheat. Our data suggest that both the A-tract and C-rich segment within the VRN-box contribute to its functionality, and provide a new view of the hypothesised role of the VRN-box in regulating transcription of the VRN1 genes. Specifically, it is proposed that combination of mutations in this region can modulate vernalization sensitivity and flowering time of wheat. Conclusions New allelic variants of the VRN-A1 and VRN-B1 genes were identified in hexaploid and tetraploid wheat. Mutations in A-tract and C-rich segments within the VRN-box of VRN-A1 are associated with modulation of the vernalization requirement and flowering time. New allelic variants will be useful in fundamental investigations into the regulation of VRN1 expression, and provide a valuable genetic resource for practical breeding of wheat. Electronic supplementary material The online version of this article (doi:10.1186/s12870-015-0691-2) contains supplementary material, which is available to authorized users.

International audience; We show the error in water-limited yields simulated by crop models which is associated with spatially aggregated soil and climate input data. Crop simulations at large scales (regional, national, continental) frequently use input data of low resolution. Therefore, climate and soil data are often generated via averaging and sampling by area majority. This may bias simulated yields at large scales, varying largely across models. Thus, we evaluated the error associated with spatially aggregated soil and climate data for 14 crop models. Yields of winter wheat and silage maize were simulated under water-limited production conditions. We calculated this error from crop yields simulated at spatial resolutions from 1 to 100 km for the state of North Rhine-Westphalia, Germany. Most models showed yields biased by

Weed control is generally considered to be essential for crop production and herbicides have become the main method used for weed control in developed countries. However, concerns about harmful environmental consequences have led to strong pressure on farmers to reduce the use of herbicides. As food demand is forecast to increase by 50% over the next century, an in-depth quantitative analysis of crop yields, weeds and herbicides is required to balance economic and environmental issues. This study analysed the relationship between weeds, herbicides and winter wheat yields using data from 150 winter wheat fields in western France. A Bayesian hierarchical model was built to take account of farmers’ behaviour, including implicitly their perception of weeds and weed control practices, on the effectiveness of treatment. No relationship was detected between crop yields and herbicide use. Herbicides were found to be more effective at controlling rare plant species than abundant weed species. These results suggest that reducing the use of herbicides by up to 50% could maintain crop production, a result confirmed by previous studies, while encouraging weed biodiversity. Food security and biodiversity conservation may, therefore, be achieved simultaneously in intensive agriculture simply by reducing the use of herbicides.

The use of cultivar mixtures to control foliar fungal diseases is well documented for windborne diseases, but remainscontroversial for splash-dispersed diseases. To try to improve this strategy, a cultivar mixture was designed consistingof two wheat cultivars with contrasted resistance to Mycosphaerella graminicola, responsible for the rainborne diseaseseptoria tritici blotch (STB), in a 1:3 susceptible:resistant ratio rather than the 1:1 ratio commonly used in previousstudies. The impact of natural STB epidemics in this cultivar mixture was studied in field experiments over 4 years.Weekly assessments of the number of sporulating lesions, pycnidial leaf area and green leaf area were carried out onthe susceptible cultivar. In years with sufficient STB pressure, disease impacts on the susceptible cultivar in the mixturewere always significantly lower than in the pure stand (e.g. 42% reduction of pycnidial leaf area for the three upperleaves in 2008 and 41% in 2009). In years with low STB pressure (2010 and 2011), a reduction of disease impactswas also shown but was not always significant. After major rainfall events, the number of sporulating lesions observedon the susceptible cultivar after one latent period was reduced on average by 45% in the mixture compared to the purestand. All the measurements showed that a susceptible cultivar was consistently protected, at least moderately, in amixture under low to moderate STB pressure. Therefore, the results prove that the design of an efficient cultivar mix-ture can include the control of STB, among other foliar diseases.Keywords: cultivar mixtures, disease resistance, Mycosphaerella graminicola, septoria tritici blotch, splash dispersal,wheat

Climate change will affect mycotoxin contamination of feed and food. Mathematical models for predicting mycotoxin concentrations in cereal grains are useful for estimating the impact of climate change on these toxins. The objective of the current study was to construct a descriptive model to estimate climate change impacts on deoxynivalenol (DON) contamination of mature wheat grown in northwestern Europe. Observational data from 717 wheat fields in Norway, Sweden, Finland, and The Netherlands were analyzed, including the DON concentrations in mature wheat, agronomical practices, and local weather. Multiple regression analyses were conducted, and the best set of explanatory variables, mainly including weather factors, was selected. The final model included the following variables: flowering date, length of time between flowering and harvest, wheat resistance to Fusarium infection, and several climatic variables related to relative humidity, temperature, and rainfall during critical stages of wheat cultivation. The model accounted for 50 % of the variance, which was sufficient to make this model useful for estimating the trends of climate change on DON contamination of wheat in northwestern Europe. Application of the model in possible climate change scenarios is illustrated.

We propose that oxidative stress resulting from an imbalance between generation and scavenging hydrogen peroxide contributes to tissue regeneration efficiency during somatic embryogenesis of hexaploid winter wheat (Triticum aestivum cv. Kamila) and organogenesis of faba bean (Vicia faba ssp. minor cv. Nadwislanski). Endogenous hydrogen peroxide content and antioxidant capacity of cells were determined in initial explants and callus cultures derived from these explants. Regeneration-competent explants (immature embryos) contained more endogenous H2O2 than explants initiated from regeneration-recalcitrant tissue (mature wheat embryos and faba bean epicotyls). Higher H2O2 levels were observed despite the higher activity of antioxidative enzymes (superoxide dismutase and catalase) and the induction of their gene expression. Calli originating from immature embryos retained the capacity of the initial explants: high H2O2 production was observed during the whole culture period. Low temperature treatment (4°C) was found to be an effective factor, which improved both regeneration ability and H2O2 production. Exogenous application to the medium of H2O2 and catalase blocker (3-aminotriazole), but not FeEDTA and superoxide dismutase blocker (diethyldithiocarbamate), also resulted in the enhancement of regeneration efficiency. These results clearly indicate that plant regeneration is specifically regulated by endogenous H2O2 and by factors, which improve its accumulation. Moreover, a study of the activity of various SOD isoforms suggests that not only the absolute concentration of H2O2, but also its localisation might be responsible for controlling regeneration processes.

Miscanthus, a perennial, C-4 grass, has numerous advantages for biomass production, notably its high yield per hectare and low input requirements. However, establishment of this crop may be affected in Europe by frost damage when stem emergence occurs early in the year. The principal aim of this study was to quantify the impact of frost on young miscanthus shoots at different leaf-stages, and to characterise inter-species variations in frost tolerance. Four clones belonging to two species were tested at three leaf stages in a climate-controlled chamber simulating acclimation conditions and frost treatments. Frost tolerance was scored using a 0-6 visual assessment scale and analysed with nonparametric tests. We were thus able to show that more developed plants (6 or 7-leaf stage) were less frost tolerant than those at the 3 or 5-leaf stage. Plants at the 6 or 7-leaf stage also displayed differences in tolerance between clones. The leaf-stage of the plant is linked to apex height, and this appeared to play a role in frost tolerance. M. sinensis displayed variable frost tolerance (tolerance score of between 3.6 and 4.9), although the three clones observed were always more frost tolerant than M. x giganteus (with a score of 3). Moreover, the differences in frost tolerance were negatively correlated (r= -0.94) with the mean leaf surface area of clones at the time of frost exposure. Finally, we observed that acclimation at 12 C under strong light intensity (600 mu mol m(-2) s(-1)) enabled an increase in the tolerance of young shoots in all the clones tested. (C) 2011 Published by Elsevier B.V.

Many studies have evaluated the effects of nitrogen-fertilizer rates on Fusarium head blight (FHB) and mycotoxin contamination of wheat (Triticum aestivum) in both conventional and organic systems. Results are often conflicting while underlying mechanisms remain illusive. This study aimed to provide insights into these conflicting results. Spring wheat was grown at two sites in the Netherlands in 2006 and 2007 using compost-, slurry-, or farmyard manure-based organic fertilizing systems, each with five total-nitrogen rates. In 2006, overall Fusarium infection levels and deoxynivalenol (DON) contents of the grain were low, and the data suggested a positive, multivariate relation between DON content and grain-nitrogen content. Higher DON contents were also accompanied by more vegetative growth (straw biomass). In 2007, plant density of the crop was relatively low while overall FHB infection levels and DON contents were relatively high. In this year, no clear correlations between straw dry matter production or grain-nitrogen content and DON content were found, while weed infestation increased with higher nitrogen levels. Practical implications of the multivariate relations between N-rates, N-contents, DON, microclimate and the presence of weeds are discussed.

Wheat quality is an important target trait. Previous studies mainly focus on storage protein, but their contribution to quality is partial, and most loci for quality are still undetected. Wild species of wheat are valuable resources for wheat improvement and introgression lines (ILs) are the ideal materials for detecting quantitative trait loci (QTL). In this study, a set of 82 BC5 F2-6 ILs, carrying a range of introgressed chromosome segments from a synthetic hexaploid wheat Am3 (Triticum carthlicum x Aegilops tauschii), was developed and genotyped with 170 microsatellite markers. QTL analysis was performed for 14 parameters, sodium dodecyl sulfate sedimentation volume, grain protein content (GPC), grain hardness and 11 mixograph parameters, associated with end-use quality of wheat, using the materials harvested in three environments. This led to the detection of 116 QTL, with c. 95% of the positive alleles contributed by Am3. Six important and novel genomic regions for bread-making quality were found on chromosomes 2D, 3A, 4A, 4B, 5A and 6A. These loci for bread-making quality showed pleiotropy and had large positive effects on several quality parameters with no or very weak negative effect on grain yield, thus demonstrating the value of synthetic wheat as a source of useful genetic variation for the improvement of bread wheat quality.