How changes in climate and agricultural practices influenced wheat production in Western Europe

Mitigating drought-induced oxidative stress in wheat (Triticum aestivum L.) through foliar application of sulfhydryl thiourea

Drought stress is a major abiotic stress affecting the performance of wheat (Triticum aestivum L.). The current study evaluated the effects of drought on wheat phenology, physiology, and biochemistry; and assessed the effectiveness of foliar-applied sulfhydryl thiourea to mitigate drought-induced oxidative stress. The treatments were: wheat varieties; V1 = Punjab-2011, V2 = Galaxy-2013, V3 = Ujala-2016, and V4 = Anaaj-2017, drought stress; D1 = control (80% field capacity [FC]) and D2 = drought stress (40% FC), at  the reproductive stage, and sulfhydryl thiourea (S) applications; S0 = control-no thiourea and S1 = foliar thiourea application @ 500 mg L-1. Results of this study indicated that growth parameters, including height, dry weight, leaf area index (LAI), leaf area duration (LAD), crop growth rate (CGR), net assimilation rate (NAR) were decreased under drought stress-40% FC, as compared to control-80% FC. Drought stress reduced the photosynthetic efficiency, water potential, transpiration rates, stomatal conductances, and relative water contents by 18, 17, 26, 29, and 55% in wheat varieties as compared to control. In addition, foliar chlorophyll a, and b contents were also lowered under drought stress in all wheat varieties due to an increase in malondialdehyde and electrolyte leakage. Interestingly, thiourea applications restored wheat growth and yield attributes by improving the production and activities of proline, antioxidants, and osmolytes under normal and drought stress as compared to control. Thiourea applications improved the osmolyte defense in wheat varieties as peroxidase, superoxide dismutase, catalase, proline, glycine betaine, and total phenolic were increased by 13, 20, 12, 17, 23, and 52%; while reducing the electrolyte leakage and malondialdehyde content by 49 and 32% as compared to control. Among the wheat varieties, Anaaj-2017 showed better resilience towards drought stress and also gave better response towards thiourea application based on morpho-physiological, biochemical, and yield attributes as compared to Punjab-2011, Galaxy-2013, and Ujala-2016. Eta-square values showed that thiourea applications, drought stress, and wheat varieties were key contributors to most of the parameters measured. In conclusion, the sulfhydryl thiourea applications improved the morpho-physiology, biochemical, and yield attributes of wheat varieties, thereby mitigating the adverse effects of drought.  Moving forward, detailed studies pertaining to the molecular and genetic mechanisms under sulfhydryl thiourea-induced drought stress tolerance are warranted.

Analysis of the Effects of the Vrn-1 and Ppd-1 Alleles on Adaptive and Agronomic Traits in Common Wheat (Triticum aestivum L.)

Wheat heading time is primarily governed by two loci: VRN-1 (response to vernalization) and PPD-1 (response to photoperiod). Five sets of near-isogenic lines (NILs) were studied with the aim of investigating the effect of the aforementioned genes on wheat vegetative period duration and 14 yield-related traits. Every NIL was sown in the hydroponic greenhouse of the Institute of Cytology and Genetics, SB RAS. To assess their allelic composition at the VRN-1 and PPD-1 loci, molecular markers were used. It was shown that HT in plants with the Vrn-A1vrn-B1vrn-D1 genotype was reduced by 29 and 21 days (p < 0.001) in comparison to HT in plants with the vrn-A1Vrn-B1vrn-D1 and the vrn-A1vrn-B1Vrn-D1 genotypes, respectively. In our study, we noticed a decrease in spike length as well as spikelet number per spike parameter for some NIL carriers of the Vrn-A1a allele in comparison to carriers of the Vrn-B1 allele. PCA revealed three first principal components (PC), together explaining more than 70% of the data variance. Among the studied genetic traits, the Vrn-A1a and Ppd-D1a alleles showed significant correlations with PCs. Regarding genetic components, significant correlations were calculated between PC3 and Ppd-B1a (-0.26, p < 0.05) and Vrn-B1 (0.57, p < 0.05) alleles. Thus, the presence of the Vrn-A1a allele affects heading time, while Ppd-D1a is associated with plant height reduction.

Mapping the race between crop phenology and climate risks for wheat in France under climate change

Climate change threatens food security by affecting the productivity of major cereal crops. To date, agroclimatic risk projections through indicators have focused on expected hazards exposure during the crop's current vulnerable seasons, without considering the non-stationarity of their phenology under evolving climatic conditions. We propose a new method for spatially classifying agroclimatic risks for wheat, combining high-resolution climatic data with a wheat's phenological model. The method is implemented for French wheat involving three GCM-RCM model pairs and two emission scenarios. We found that the precocity of phenological stages allows wheat to avoid periods of water deficit in the near future. Nevertheless, in the coming decades the emergence of heat stress and increasing water deficit will deteriorate wheat cultivation over the French territory. Projections show the appearance of combined risks of heat and water deficit up to 4 years per decade under the RCP 8.5 scenario. The proposed method provides a deep level of information that enables regional adaptation strategies: the nature of the risk, its temporal and spatial occurrence, and its potential combination with other risks. It's a first step towards identifying potential sites for breeding crop varieties to increase the resilience of agricultural systems.

An insight into the impact of climate factors associated with altitude on wheat volatiles' fingerprints at harvest using multivariate statistical analysis

BACKGROUND

Climate changes associated with global warming are increasingly affecting the quality of cultivated crops. Cultivation at different altitudes and similar latitudes may offer an extraordinarily useful opportunity to obtain a diversificated dataset of climate variables and to further investigate their effect on crop quality. This study evaluated the effect of climate indices - temperature, rainfall precipitation and solar radiation data - on commercial parameters and the volatile organic compound (VOC) profile of wheat at harvest.

RESULTS

Three common and durum wheat varieties, including two heritage wheats, were sown in experimental fields sited at three altitudes for 3 years consecutively, and they were analyzed for their yield, grading parameters, and VOC profiles. The datasets were processed by partial least squares regression (PLS-R) and the results indicate that summer days (SU25) and diurnal temperature range (ΔT) are the climate indices mainly responsible for the VOC profile changes in both common and durum wheat. Accumulated growth degree days (GDD), consecutive dry days (CDD), and accumulated solar radiation (ASR) induced species-specific responses. Terpenes represented the chemical class of VOCs most affected by stresses, followed by ketones and alcohols, which were affected by CDD, GDD, and ASR.

CONCLUSION

This study showed a selective response of wheat to abiotic stresses associated with climate variables in terms of VOC synthesis. Its findings may be relevant in several fields, from plant ecology to agronomy and food quality, with implications for local economic strategies. © 2023 Society of Chemical Industry.

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.

Timing and intensity of heat and drought stress determine wheat yield losses in Germany

Crop yields are increasingly affected by climate change-induced weather extremes in Germany. However, there is still little knowledge of the specific crop-climate relations and respective heat and drought stress-induced yield losses. Therefore, we configure weather indices (WIs) that differ in the timing and intensity of heat and drought stress in wheat (Triticum aestivum L.). We construct these WIs using gridded weather and phenology time series data from 1995 to 2019 and aggregate them with Germany-wide municipality level on-farm wheat yield data. We statistically analyze the WI's explanatory power and region-specific effect size for wheat yield using linear mixed models. We found the highest explanatory power during the stem elongation and booting phase under moderate drought stress and during the reproductive phase under moderate heat stress. Furthermore, we observed the highest average yield losses due to moderate and extreme heat stress during the reproductive phase. The highest heat and drought stress-induced yield losses were observed in Brandenburg, Saxony-Anhalt, and northern Bavaria, while similar heat and drought stresses cause much lower yield losses in other regions of Germany.

Impacts of heat, drought, and combined heat-drought stress on yield, phenotypic traits, and gluten protein traits: capturing stability of spring wheat in excessive environments

Wheat production and end-use quality are severely threatened by drought and heat stresses. This study evaluated stress impacts on phenotypic and gluten protein characteristics of eight spring wheat genotypes (Diskett, Happy, Bumble, SW1, SW2, SW3, SW4, and SW5) grown to maturity under controlled conditions (Biotron) using RGB imaging and size-exclusion high-performance liquid chromatography (SE-HPLC). Among the stress treatments compared, combined heat-drought stress had the most severe negative impacts on biomass (real and digital), grain yield, and thousand kernel weight. Conversely, it had a positive effect on most gluten parameters evaluated by SE-HPLC and resulted in a positive correlation between spike traits and gluten strength, expressed as unextractable gluten polymer (%UPP) and large monomeric protein (%LUMP). The best performing genotypes in terms of stability were Happy, Diskett, SW1, and SW2, which should be further explored as attractive breeding material for developing climate-resistant genotypes with improved bread-making quality. RGB imaging in combination with gluten protein screening by SE-HPLC could thus be a valuable approach for identifying climate stress-tolerant wheat genotypes.

Development and the Effect of Weather and Mineral Fertilization on Grain Yield and Stability of Winter Wheat following Alfalfa-Analysis of Long-Term Field Trial

Within the framework of a long-term experiment, established in 1955, we evaluated the development and effects of weather and mineral fertilization (Control, NPK1, NPK2, NPK3, NPK4) on the yield and stability of winter wheat following alfalfa. In total, 19 seasons were analysed. The weather changed considerably at the experimental site. Significant increases in minimal, mean, and maximal temperatures were dated to the period 1987-1988, while precipitation remained the same to this day (insignificantly increasing trend by 0.5 mm per annum). Rising temperatures in November, May, and July positively affected wheat grain yield, especially in treatments with higher N doses. No relationship between yield and precipitation was recorded. Highest inter-annual yield variability was recorded in Control and NPK4 treatments. Although minerally fertilized treatments provided slightly higher yields, the difference between Control and NPK treatments was insignificant. According to the linear-plateau response model, the recommended dose of 44 kg ha^-1 N corresponds with yield of 7.4 t ha^-1, while Control provides an average yield of 6.8 t ha^-1. The application of higher doses did not lead to significant grain yield increase. Alfalfa as a preceding crop reduces the need of N fertilization and contributes to sustainable conventional agriculture, however, its share in crop rotations is decreasing both in the Czech Republic and in Europe.

Environmental Filtering Drives Fungal Phyllosphere Community in Regional Agricultural Landscapes

To adapt to climate change, several agricultural strategies are currently being explored, including a shift in land use areas. Regional differences in microbiome composition and associated phytopathogens need to be considered. However, most empirical studies on differences in the crop microbiome focused on soil communities, with insufficient attention to the phyllosphere. In this study, we focused on wheat ears in three regions in northeastern Germany (Magdeburger Börde (MBB), Müncheberger Sander (MSA), Uckermärkisches Hügelland (UKH)) with different yield potentials, soil, and climatic conditions. To gain insight into the fungal community at different sites, we used a metabarcoding approach (ITS-NGS). Further, we examined the diversity and abundance of Fusarium and Alternaria using culture-dependent and culture-independent techniques. For each region, the prevalence of different orders rich in phytopathogenic fungi was determined: Sporidiobolales in MBB, Capnodiales and Pleosporales in MSA, and Hypocreales in UKH were identified as taxonomic biomarkers. Additionally, F. graminearum was found predominantly in UKH, whereas F. poae was more abundant in the other two regions. Environmental filters seem to be strong drivers of these differences, but we also discuss the possible effects of dispersal and interaction filters. Our results can guide shifting cultivation regions to be selected in the future concerning their phytopathogenic infection potential.

Determining the environmental and economic implications of lupin cultivation in wheat-based organic rotation systems in Galicia, Spain

Crop rotation represents a potentially sustainable strategy to address environmental problems of intensive agricultural practices, such as soil degradation, biodiversity reduction, and greenhouse gas emissions. This manuscript assesses the environmental and economic implications of introducing lupin cultivation into winter wheat-based rotation systems under an organic regime in Galicia, Spain. Life Cycle Assessment methodology was used to determine the environmental impacts of three rotation systems over a six-year period: lupin → wheat → rapeseed (OA1), lupin → potato → wheat (OA2), and lupin → wheat → rapeseed ‖ maize (OA3). For a robust assessment, three functional units were applied: land management (ha), economic indicator (gross margin in euros) and protein content (1 kg of protein-corrected grain). Moreover, the environmental profiles were compared with rotation systems without lupin crop in a conventional regime. In terms of Global Warming, impacts of about 2214, 3119 and 766 kg CO₂eq·ha^-1 were obtained for OA1, OA2 and OA3, respectively. Moreover, OA1 is the best rotation in terms of land and protein. Meanwhile, OA2 rotation is the best choice in the economic function, as it obtained the highest level of gross margin (5708 €·ha^-1). Furthermore, with the exception of acidification, organic systems are less impactful than conventional systems. Ammonia emissions from the use of manure are the reason for these higher impacts. Organic rotations OA1 and OA2 have about 6 % or 15 % less gross margin than their conventional counterparts, respectively, however, an increase of 28 % was obtained for rotation OA3. This study helps decision-makers to implement environmentally and economically viable strategies.

A systematic literature review of life cycle assessments in the durum wheat sector

It is recognised today that the global food system does not always deliver good nutrition for all human beings, and, additionally, dramatically contributes to climate change, environmental degradation, and biodiversity loss. In particular, the cereal sector threatens biodiversity and ecosystem functions, due to environmentally harmful farming activities, that critically alter climate conditions, along with energy, land, and water resources. According to this paper's authors' opinion, this supports the rationale of conducting a systematic literature review of Life Cycle Assessments (LCAs) in the durum wheat (DW) sector, to highlight environmental hotspots and improvement potentials in the phases of cultivation and processing into finished products like pasta and bread. Methodological aspects were also discussed in this paper, to provide useful insights on how to best perform LCA in such agri-food supply chains. Given the findings from the papers reviewed, the authors could document that the cultivation phase is the primary environmental hotspot of DW-derived food products and suggested several mitigation and improvements solution including, organic farming practices, diversified cropping systems, reduction of N fertilisers and pesticides application, and irrigation optimisation strategies. Furthermore, the review highlighted that there exist two main gaps in the literature, mainly related to the scarce attention on the organic farming sector and DW landraces, and the lack of nutritional-property accounting in LCAs. Finally, although specific, the review may be of interest to researchers, LCA practitioners, farmers and producers, policy- and decision-makers, and other stakeholders, and could support the promotion of environmental sustainability in the DW sector.

Effects of climatic and cultivar changes on winter wheat phenology in central Lithuania

It is essential to understand how climate change and varieties affect crop phenology and yields to adapt to future climate change. The aim of this study was to analyse the phenological development trends of three winter wheat cultivars (1990-2020) to identify the most critical meteorological-climatic factors influencing the development and yield of the cultivars and to investigate the heat requirements for each phenological phase to reveal the potential of the different cultivars to adapt to the warming climate. The observed dates of green-up, the beginning of stem elongation, and the grain development advanced significantly, but the timing of maturity changed insignificantly during the period of 1990-2020. The most marked change was related to the shortening of the period from sowing to green-up. The green-up dates were related to the mean temperature of the period after sowing. The occurrence of stem elongation and grain development dates were negatively correlated with the mean temperature in May. Significant correlations were found between temperature and duration from sowing to green-up and positive from stem elongation to grain development. The change of cultivar led to earlier green-up and grain development dates, but cultivar choise had no influence on sowing, stem elongation, and maturity dates from 1990 to 2020. The newer cultivar Skagen was more successful in exploiting increased thermal resources. The heat requirements remained almost unchanged during the vegetative development period, while the heat amount required during the reproductive period increased by about 15%. These findings demonstrate that the choice of crop cultivars with higher thermal requirements may be an appropriate adaptation mean to achieve higher yields in response to climate change, at least in the middle latitudes.

Offsetting the environmental impacts of single or multi-product biorefineries from wheat straw

Moving toward a bioeconomy system is fundamental to climate change mitigation, nevertheless, the biotechnological routes should guarantee an environmental sustainability. Isobutene, a precursor in several industrial applications, is one of those chemicals that the environmental effects of its bio-based production have been scarcely explored. This study aims to assess the environmental performance of two biorefinery systems: the first one focuses only on the production of isobutene (I) and the second one on the co-production with lignin (I + L), both from the valorisation of wheat straw. The Life Cycle Assessment methodology is used to determine the environmental impacts considering mid-point and end-point categories. Biorefineries report 0.65 and 1.32 kg CO₂-eq per kg of biomass processed for I and I + L system, respectively. The most affected endpoint damage category corresponds to Human Health, regardless of the scenarios. Moreover, the pre-treatment stage constitutes the main hotspot of both systems considering midpoint and endpoint perspectives.

The Effects of Weather and Fertilization on Grain Yield and Stability of Winter Wheat Growing on Orthic Luvisol—Analysis of Long-Term Field Experiment

Based on a long-term experiment in Prague, established in 1954, we analyzed the effect of weather and seven fertilization treatments (mineral and manure treatments) on winter wheat grain yield (GY) and stability. In total, 23 seasons were analyzed, where a wheat crop followed a summer crop of potatoes. A regression analysis showed that, since the experiment started, there has been a significant increase in the annual daily maximum, average, and minimum temperature of 0.5 °C, and an increase in annual rainfall of 0.3 mm. Grain yield was positively associated with April precipitation, mean daily temperature in October, and daily maximum temperature in February. Yields were most stable between years with two fertilizer treatments that supplied a mean of 47 kg N ha⁻¹yr⁻¹, 54 kg P ha⁻¹yr⁻¹, and 108 kg K ha⁻¹yr⁻¹. The rate of N at which grain yield was optimized was determined according to the linear-plateau (LP) and quadratic response models as 44 kg N ha⁻¹yr⁻¹ for the long-strawed varieties and 87 kg N ha⁻¹yr⁻¹for short-strawed varieties.A gradual increase in yields was observed in all treatments, including the unfertilized control, which was attributed to improved varieties rather than to a changing climate.

Mapping Crop Types of Germany by Combining Temporal Statistical Metrics of Sentinel-1 and Sentinel-2 Time Series with LPIS Data

Nationwide and consistent information on agricultural land use forms an important basis for sustainable land management maintaining food security, (agro)biodiversity, and soil fertility, especially as German agriculture has shown high vulnerability to climate change. Sentinel-1 and Sentinel-2 satellite data of the Copernicus program offer time series with temporal, spatial, radiometric, and spectral characteristics that have great potential for mapping and monitoring agricultural crops. This paper presents an approach which synergistically uses these multispectral and Synthetic Aperture Radar (SAR) time series for the classification of 17 crop classes at 10 m spatial resolution for Germany in the year 2018. Input data for the Random Forest (RF) classification are monthly statistics of Sentinel-1 and Sentinel-2 time series. This approach reduces the amount of input data and pre-processing steps while retaining phenological information, which is crucial for crop type discrimination. For training and validation, Land Parcel Identification System (LPIS) data were available covering 15 of the 16 German Federal States. An overall map accuracy of 75.5% was achieved, with class-specific F1-scores above 80% for winter wheat, maize, sugar beet, and rapeseed. By combining optical and SAR data, overall accuracies could be increased by 6% and 9%, respectively, compared to single sensor approaches. While no increase in overall accuracy could be achieved by stratifying the classification in natural landscape regions, the class-wise accuracies for all but the cereal classes could be improved, on average, by 7%. In comparison to census data, the crop areas could be approximated well with, on average, only 1% of deviation in class-specific acreages. Using this streamlined approach, similar accuracies for the most widespread crop types as well as for smaller permanent crop classes were reached as in other Germany-wide crop type studies, indicating its potential for repeated nationwide crop type mapping.

Genetics, not environment, contributed to winter wheat yield gains in Ontario, Canada

Changes in entries' market classes and genetic improvements within classes-not environmental changes-enhanced yields over thirty-one years of wheat trials. Correlations between yields and ancestries drove genomic prediction accuracies. Increasing crop yields is important for enhancing farmers' livelihoods, meeting market demands, and reducing the environmental impact of agriculture. We analyzed the yield trends of Ontario winter wheat variety trials between 1988 and 2018. Over this period, wheat yields steadily increased by 38 kg ha^-1 yr^-1, or 0.68% yr^-1 relative to the mean. While fungicide treatment of trials contributed a one-time 670 kg ha^-1 yield increase, yields were otherwise unaffected by long-term changes in agronomic practice, climate, or other non-genetic factors. Genetic improvement entirely accounted for yield improvement. Market class changes over the 31 year span accounted for some yield improvement. More importantly, genetic improvement occurred within each market class. Entry yield estimates calculated from genomic prediction models strongly correlated with field estimated yields with a mean r of 0.68. Genomic prediction accuracies were high because yields differed across genetically distinct subpopulations. Despite environmental changes, genetic improvement will likely increase Ontario winter wheat yields into the future.

Genetic control of compatibility in crosses between wheat and its wild or cultivated relatives

In the recent years, the agricultural world has been progressing towards integrated crop protection, in the context of sustainable and reasoned agriculture to improve food security and quality, and to preserve the environment through reduced uses of water, pesticides, fungicides or fertilisers. For this purpose, one possible issue is to cross-elite varieties widely used in fields for crop productions with exotic or wild genetic resources in order to introduce new diversity for genes or alleles of agronomical interest to accelerate the development of new improved cultivars. However, crossing ability (or crossability) often depends on genetic background of the recipient varieties or of the donor, which hampers a larger use of wild resources in breeding programmes of many crops. In this review, we tried to provide a comprehensive summary of genetic factors controlling crossing ability between Triticeae species with a special focus on the crossability between wheat (Triticum aestivum L.) and rye (Secale cereale), which lead to the creation of Triticale (x Triticosecale Wittm.). We also discussed potential applications of newly identified genes or markers associated with crossability for accelerating wheat and Triticale improvement by application of modern genomics technologies in breeding programmes.

Genome Editing-accelerated Re-Domestication (GEaReD) - a new major direction in plant breeding

BACKGROUND

The effects of climate change, soil depletion, a growing world population putting pressure on food safety and security are major challenges for agriculture in the 21st century. The breeding success of the green revolution has decelerated and current programs can only offset the yield affecting factors.

PURPOSE AND SCOPE

New approaches are urgently needed and we propose "Genome Editing-accelerated Re-Domestication" (GEaReD) as a major new direction in plant breeding. By combining the upcoming technologies for phenotyping, omics, and artificial intelligence with the promising new CRISPR-toolkits, this approach is closer than ever.

SUMMARY AND CONCLUSION

Wild relatives of current crops are often adapted to harsh environments and have a high genetic diversity. Redomestication of wild barley or teosinte could generate new cultivars adapted to environmental changes. De novo domestication of perennial relatives such as Hordeum bulbosum could counter soil depletion and increase soil carbon. Recent research already proved the principle of redomestication in tomato and rice and therefore laid the foundation for GEaReD. This article is protected by copyright. All rights reserved.

Environmental assessment of the production of itaconic acid from wheat straw under a biorefinery approach

This study performs the environmental assessment of itaconic acid (IA) production from wheat straw. The Life Cycle Assessment (LCA) methodology is used to determine the environmental hotspots, considering impact categories such as Global Warming (GW), Fossil Resource Scarcity (FRS), Water Consumption (WC), among others. A sensitivity analysis was performed considering an optimization of the steam explosion process and 100% renewable energy. Results report an impact of about 14.33 kg CO₂ eq in GW, 4.15 kg of oil eq in FRS, for each kg of IA produced for the baseline scenario. Moreover, the pretreatment and fermentation stages constitute hotspots of the IA production. In addition, using a renewable energy source in production would reduce the impact by 82% in GW, 71% in PM and 82% in FRS categories. The optimization of the steam explosion process presents a better performance in GW and FRS but also lies in an increase in WC.

Breeding for Economically and Environmentally Sustainable Wheat Varieties: An Integrated Approach from Genomics to Selection

There is currently a strong societal demand for sustainability, quality, and safety in bread wheat production. To address these challenges, new and innovative knowledge, resources, tools, and methods to facilitate breeding are needed. This starts with the development of high throughput genomic tools including single nucleotide polymorphism (SNP) arrays, high density molecular marker maps, and full genome sequences. Such powerful tools are essential to perform genome-wide association studies (GWAS), to implement genomic and phenomic selection, and to characterize the worldwide diversity. This is also useful to breeders to broaden the genetic basis of elite varieties through the introduction of novel sources of genetic diversity. Improvement in varieties particularly relies on the detection of genomic regions involved in agronomical traits including tolerance to biotic (diseases and pests) and abiotic (drought, nutrient deficiency, high temperature) stresses. When enough resolution is achieved, this can result in the identification of candidate genes that could further be characterized to identify relevant alleles. Breeding must also now be approached through in silico modeling to simulate plant development, investigate genotype × environment interactions, and introduce marker-trait linkage information in the models to better implement genomic selection. Breeders must be aware of new developments and the information must be made available to the world wheat community to develop new high-yielding varieties that can meet the challenge of higher wheat production in a sustainable and fluctuating agricultural context. In this review, we compiled all knowledge and tools produced during the BREEDWHEAT project to show how they may contribute to face this challenge in the coming years.

Improving Grain Yield via Promotion of Kernel Weight in High Yielding Winter Wheat Genotypes

Simple Summary

Improving plant net photosynthetic rates and accelerating water-soluble carbohydrate accumulation play an important role in increasing the carbon sources for wheat kernel growth and yield. The objective of this study was to quantify the relative yield contribution by analyzing the photosynthesis rate of flag leaf, water-soluble carbohydrate content of flag leaf, flag leaf sheath and stem, and other agronomic and physiological traits in 15 wheat cultivars released in Shandong Province, China between 1969 and 2006. Our results suggest that increase of flag leaf photosynthesis and WSC had a positive effect of 0.593 on the TKW, and thus benefit for developing high yielding wheat cultivars.

Abstract

Improving plant net photosynthetic rates and accelerating water-soluble carbohydrate accumulation play an important role in increasing the carbon sources for yield formation of wheat (Triticum aestivum L.). Understanding and quantify the contribution of these traits to grain yield can provide a pathway towards increasing the yield potential of wheat. The objective of this study was to identify kernel weight gap for improving grain yield in 15 winter wheat genotypes grown in Shandong Province, China. A cluster analysis was conducted to classify the 15 wheat genotypes into high yielding (HY) and low yielding (LY) groups based on their performance in grain yield, harvest index, photosynthetic rate, kernels per square meter, and spikes per square meter from two years of field testing. While the grain yield was significantly higher in the HY group, its thousand kernel weight (TKW) was 8.8% lower than that of the LY group (p < 0.05). A structural equation model revealed that 83% of the total variation in grain yield for the HY group could be mainly explained by TKW, the flag leaf photosynthesis rate at the grain filling stage (Pn75), and flag leaf water-soluble carbohydrate content (WSC) at grain filling stage. Their effect values on yield were 0.579, 0.759, and 0.444, respectively. Our results suggest that increase of flag leaf photosynthesis and WSC could improve the TKW, and thus benefit for developing high yielding wheat cultivars.

The effect of silicon supply on photosynthesis and carbohydrate metabolism in two wheat (Triticum aestivum L.) cultivars contrasting in response to phosphorus nutrition

Phosphorus (P) deficiency affects agricultural systems by limiting crop quality and yield. Studies have suggested that silicon (Si) improves P uptake in plants grown under P deficiency. However, the effects of Si on photosynthesis and carbohydrate metabolism under P stress remain unclear. We performed a hydroponic study using two wheat cultivars with contrasting sensitivity to P deficiency (Púrpura, sensitive; Fritz, semi-tolerant) that were exposed to P (0, 0.01, or 0.1 mM) and Si (0 or 2 mM), and we evaluated the photosynthetic performance and metabolic alterations. In plants from the sensitive cultivar undergoing P deficiency, Si application increased sucrose levels, starch breakdown and length of shoots, and also improved plant dry weight. In Fritz (the semi-tolerant cultivar), Si exposure reduced P concentration, and increased shoot length and P use efficiency (PUE) under P shortage. Interestingly, Si application altered cell wall composition, which was associated with higher mesophyll conductance and net CO₂ assimilation in Fritz plants grown under P stress. Together, our results indicate that under P deficiency, Si nutrition positively affects photosynthesis and carbohydrate levels in a genotype-dependent manner. Furthermore, these results suggest that Si plays an important role in maintaining high photosynthetic rates in wheat plants undergoing P deficiency.

Introducing Beneficial Alleles from Plant Genetic Resources into the Wheat Germplasm

Wheat (Triticum sp.) is one of the world's most important crops, and constantly increasing its productivity is crucial to the livelihoods of millions of people. However, more than a century of intensive breeding and selection processes have eroded genetic diversity in the elite genepool, making new genetic gains difficult. Therefore, the need to introduce novel genetic diversity into modern wheat has become increasingly important. This review provides an overview of the plant genetic resources (PGR) available for wheat. We describe the most important taxonomic and phylogenetic relationships of these PGR to guide their use in wheat breeding. In addition, we present the status of the use of some of these resources in wheat breeding programs. We propose several introgression schemes that allow the transfer of qualitative and quantitative alleles from PGR into elite germplasm. With this in mind, we propose the use of a stage-gate approach to align the pre-breeding with main breeding programs to meet the needs of breeders, farmers, and end-users. Overall, this review provides a clear starting point to guide the introgression of useful alleles over the next decade.

Dissecting Bread Wheat Heterosis through the Integration of Agronomic and Physiological Traits

To meet the challenge of feeding almost 10 billion people by 2050, wheat yield has to double by 2050. However, over the past 20 years, yield increase has slowed down and even stagnated in the main producing countries. Following the example of maize, hybrids have been suggested as a solution to overcome yield stagnation in wheat. However, wheat heterosis is still limited and poorly understood. Gaining a better understanding of hybrid vigor holds the key to breed for better varieties. To this aim, we have developed and phenotyped for physiological and agronomic traits an incomplete factorial design consisting of 91 hybrids and their nineteen female and sixteen male parents. Monitoring the plant development with normalized difference vegetation index revealed that 89% of the hybrids including the five higher yielding hybrids had a longer grain filling phase with a delayed senescence that results in larger grain size. This average increase of 7.7% in thousand kernel weight translated to a positive mid-parent heterosis for grain yield for 86% of hybrids. In addition, hybrids displayed a positive grain protein deviation leading to a +4.7% heterosis in protein yield. These results shed light on the physiological bases underlying yield heterosis in wheat, paving new ways to breed for better wheat hybrids.

Mitigation of climate change and environmental hazards in plants: Potential role of the beneficial metalloid silicon

In the last decades, the concentration of atmospheric CO₂ and the average temperature have been increasing, and this trend is expected to become more severe in the near future. Additionally, environmental stresses including drought, salinity, UV-radiation, heavy metals, and toxic elements exposure represent a threat for ecosystems and agriculture. Climate and environmental changes negatively affect plant growth, biomass and yield production, and also enhance plant susceptibility to pests and diseases. Silicon (Si), as a beneficial element for plants, is involved in plant tolerance and/or resistance to various abiotic and biotic stresses. The beneficial role of Si has been shown in various plant species and its accumulation relies on the root's uptake capacity. However, Si uptake in plants depends on many biogeochemical factors that may be substantially altered in the future, affecting its functional role in plant protection. At present, it is not clear whether Si accumulation in plants will be positively or negatively affected by changing climate and environmental conditions. In this review, we focused on Si interaction with the most important factors of global change and environmental hazards in plants, discussing the potential role of its application as an alleviation strategy for climate and environmental hazards based on current knowledge.

The optimization of wheat yield through adaptive crop management in a changing climate: evidence from China

BACKGROUND

Adaptive crop management is critical to food security in a changing climate, but the respective contributions of climate change and crop management to yields remain unclear. Thus, we distinguished and quantified the respective contribution of climate change and crop management on wheat yield between 1981 and 2018 in China, using first-difference multivariate regression model.

RESULTS

Wheat production in China has increased over the past four decades. Under the sole impact of climate change, wheat yield generally decreased (-5.45 to +1.09% decade^-1 ). Crop management increased the wheat yield from 7.11 to 19.94% decade^-1 . Sensitivities of wheat yield to climatic variables (average temperature, accumulated sunshine hours, accumulated precipitation) were spatially heterogeneous; notably, in spring-wheat planting areas, wheat yield was more susceptible to the negative impact of warming. In terms of relative contribution, the contribution of climate change to spring wheat yield was -24.08% to -5.41%, and the contribution to winter wheat was -4.98% to +34.69%. Crop management had a positive contribution to all wheat-growing areas (65.31-96.84%).

CONCLUSION

Crop management had a greater effect on wheat yield than climate change did. Among the three climatic variables investigated, average temperature had the dominant effect on wheat yield change; the impact of precipitation was minimal but mostly negative. The results provide insight regarding the contribution of climate change and crop management to wheat yield; adaptation measures may be more effective in planting areas where crop management contributes more, which will help stakeholders optimize crop management and adaptation strategies. © 2020 Society of Chemical Industry.

Evaluating the environmental profiles of winter wheat rotation systems under different management strategies

Climate change poses a remarkable challenge to global food security, for which wheat is one of the main staple agricultural commodities. The cultivation of different varieties of winter wheat in Galicia (commercial and native) under rotation systems with potato, maize and oilseed rape was evaluated from an environmental point of view. The general approach of this study included the gathering of the inventory data of the different crops, the quantification of their environmental impacts and economic benefits, to identify the best land management system. Life Cycle Assessment (LCA) was used as environmental tool. The environmental profiles of each rotation system were reported in terms of nine impact categories. Crop rotations were analysed both per hectare and per € of gross margin, so that the information can be relevant to land-management decisions. Preference ranks were established based on an environmental normalized score for both units. The results suggest that arable operations contribute decisively to the environmental profile of the rotations. The avoided mineral fertilization processes, the carbon storage in the soil when returning straw to the field, as well as the electricity production clearly influence the environmental impact of the rotations. Scenarios that include native wheat under organic management are always the environmentally preferred ones while the preferred alternate crop depends on the reference unit. Concerning the margin gross, scenarios including the native variety report the highest profits, being the potato the preferred alternate crop. Further assessment needs to be undertaken to identify differences in the results of different ways of conducting LCA, i.e. attributional vs consequential approaches.