Reduced Wheat Yield Research Articles

Renewal of wheat cultivars enhances ozone resistance in yield but detrimentally impacts quality: a survey of Chinese wheat

The aggravation of ozone (O3) pollution poses a significant threat to agricultural production. With China being the leading wheat producer of the world, contributing 17.8% to global output, the vulnerability of wheat to O3 is of particular concern. Despite extensive research on the impacts of O3 on wheat production and the ongoing development of new wheat cultivars over the years, a connection between yield loss and the released ages of wheat cultivars under O3 stress remains unestablished. Addressing this, the experiment was carried out at the Yangzhou Rice and Wheat Free-air Gas Concentration Enrichment (FACE) Testing Base in China, using 17 wheat cultivars developed since the 1970s as experimental materials. The elevated O3 concentration in the test was 1.5 times higher than that in a normal atmosphere. The results indicated that O3 led to a significant reduction in wheat yield of 18.19%. The yield of cultivars released in the 1970s, 1980s, 1990s, and after 2000, decreased by 24.9%, 23.3%, 19.8%, and 14.7%, respectively. Overall, the direct effect of 1,000-grain weight on yield was the most significant, followed by the number of grains per spike, whereas the number of spikes contributed least to the yield components. To enhance resistance to O3 stress in future breeding efforts, increasing the 1,000-grain weight should be a primary objective. Our findings also revealed that elevated O3 concentration led to higher sedimentation values and protein content while lowering bulk density, hardness, and starch content. As the release age approaches, the rate of decrease in bulk density diminishes gradually. In terms of hardness, sedimentation value, and starch content, varieties released in the 1990s exhibited less sensitivity, whereas those released after the 2000s experienced the most significant changes in protein content. It is worth noting that the impact on the nutritional quality of modern cultivars is particularly significant, particularly regarding starch and protein content. Stress indices indicate that the cultivars released after 2000 exhibit stronger resistance to yield loss. The Yangmai series cultivars appear to be promising parental lines for future breeding programs aimed at developing O3-resistant wheat.

Impact of Climate Change in Wheat Yield and Water Productivity-Review

Climate change is linked to many catastrophic events and causes many disasters for people around the world. We cannot say that just those impoverished countries are impacted by the worsening effects of climate change, when wealthier nations continue to lose billions of dollars and thousands of lives year. This review work's primary goal was to determine how climate change affects crop water requirements and productivity while also offering recommendations. Numerous books and papers, both published and unpublished, were reviewed as part of the methodology. The outcome showed that the impact of climate change will vary by region and could be either good or unfavorable. In some regions of the world, raising the temperature by just one degrees Celsius may significantly reduce wheat yield productivity, but in other regions, it will enhance yield and water productivity. According to those studies, despite an increase in yield and water productivity, the high levels of carbon dioxide in the environment will cause the quality to deteriorate. Additionally. According to the reports, depending on various situations and horizons with sowing dates as well, the water need for wheat production will fall by 10% to 32% as a result of temperature increases. Researchers also underlined that water productivity will occasionally decline if mitigating efforts are not made to address the effects of climate change.

Strategic Switching from Conventional Urea to Nano-Urea for Sustaining the Rice-Wheat Cropping System.

In the face of declining crop yields, inefficient fertilizer usage, nutrient depletion, and limited water availability, the efficiency of conventional NPK fertilizers is a critical issue in India. The hypothesis of this study posits that nano-nitrogen could enhance growth and photosynthetic efficiency in crop plants compared to conventional fertilizers. For this, a randomized block design (RBD) field experiment was conducted with six treatments: no nitrogen (T1), 100% N through urea (T2), and varying levels of N replacement with nano-nitrogen (33%: T3; 50%: T4; 66%: T5; and 100%: T6). Morphological and physiological traits and yield attributes were measured at physiological maturity, and yield attributes were measured at harvest. Results showed that 33% nitrogen replacement with nano-nitrogen (T3) outperformed conventional urea (T2) in physiological traits and achieved higher grain yields (3789 kg/ha for rice and 4206 kg/ha for wheat) compared to T2 (3737 kg/ha for rice and 4183 kg/ha for wheat with 100% urea). Although T4 and T5 showed statistically similar yields, they were lower than T2 and T3 for rice, while 50%, 66%, and 100% replacements reduced wheat yield by 2.49%, 8.39%, and 41.26%, respectively, compared to T2. Key enzymes of N metabolism decreased with higher nano-nitrogen substitution. Maximum nitrogen availability was observed in T2 and T3. This study concludes that nano-nitrogen is an effective strategy to enhance growth, balancing productivity and environmental sustainability.

Genome-Wide Association Studies for Wheat Height Under Different Nitrogen Conditions

Lodging causes a reduction in wheat (Triticum aestivum L.) yield and quality. A shorter plant height (PH) can reduce the incidence of lodging. The overuse of nitrogen promotes excessive vegetative growth, leads to taller plants, and increases lodging risk. Here, we utilized genome-wide association studies (GWASs) to explore the genetic basis of PH and the nitrogen effect index (NEI), a parameter to estimate the responses of PH under varying nitrogen conditions, using 21,201 SNP markers from the Illumina Wheat 90K SNP array. A total of 191 wheat varieties from Yellow and Huai Valley regions of China, as well as other global regions, were analyzed across two growing seasons under four nitrogen treatments, namely N0 (0 kg/ha), N150 (150 kg/ha), N210 (210 kg/ha), and N270 (270 kg/ha). GWAS results showed that 30 genetic markers were associated with PH, explaining phenotypic variance from 5.92% to 13.69%. Additionally, nine significant loci were associated with the NEI. Notably, markers on chromosomes 1A and 6B were linked to both PH and the NEI, which were insensitive to low- and high-nitrogen fertilizers. In addition, the PH of the three cultivars (Zhoumai16, Zhoumai13, and Bima1) showed little variation in four nitrogen fertilizer levels. This study identified key genetic markers associated with wheat PH and the NEI, providing insights for optimizing nitrogen use in wheat breeding.

YOLOv5s-Based Image Identification of Stripe Rust and Leaf Rust on Wheat at Different Growth Stages.

Stripe rust caused by Puccinia striiformis f. sp. tritici and leaf rust caused by Puccinia triticina, are two devastating diseases on wheat, which seriously affect the production safety of wheat. Timely detection and identification of the two diseases are essential for taking effective disease management measures to reduce wheat yield losses. To realize the accurate identification of wheat stripe rust and wheat leaf rust during the different growth stages, in this study, the image-based identification of wheat stripe rust and wheat leaf rust during different growth stages was investigated based on deep learning using image processing technology. Based on the YOLOv5s model, we built identification models of wheat stripe rust and wheat leaf rust during the seedling stage, stem elongation stage, booting stage, inflorescence emergence stage, anthesis stage, milk development stage, and all the growth stages. The models were tested on the different testing sets in the different individual growth stages and in all the growth stages. The results showed that the models performed differently in disease image identification. The model based on the disease images acquired during an individual growth stage was not suitable for the identification of the disease images acquired during the other individual growth stages, except for the model based on the disease images acquired during the milk development stage, which had acceptable identification performance on the testing sets in the anthesis stage and the milk development stage. In addition, the results demonstrated that wheat growth stages had a great influence on the image identification of the two diseases. The model built based on the disease images acquired in all the growth stages produced acceptable identification results. Mean F1 Score values between 64.06% and 79.98% and mean average precision (mAP) values between 66.55% and 82.80% were achieved on each testing set composed of the disease images acquired during an individual growth stage and on the testing set composed of the disease images acquired during all the growth stages. This study provides a basis for the image-based identification of wheat stripe rust and wheat leaf rust during the different growth stages, and it provides a reference for the accurate identification of other plant diseases.

Nuclear integration of MYB36 and APX-1 genes impart heat tolerance in wheat.

Elevated temperatures during grain filling stage, exceeding the optimal range by 3-4°C, not only results in a substantial yield reduction in wheat by 10-50% but activates disease and insect infestation. In this research, we introduced heat-tolerant MYB36 and APX-1 gene cassettes into wheat, employing an efficient Agrobacterium mediated transformation protocol, demonstrating higher transformation efficiency. The study encompassed the assembly of MYB36 and APX-1 gene cassettes, and confirmation of gene products in Agrobacterium, followed by the transformation of the MYB36 and APX-1 genes into wheat explants. We were able to select transgenic plant with various combinations. The transgenic plants with APX-1 gene alone produced medium sized grain and spike whereas with both APX-1 and MYB36 genes expressed individually under SPS and rd29a promoter respectively showed good tolerance to heat at 32oC at grain filling/milking stage and produced relatively bold grains. While non-transgenic plants grains were wrinkled with thin spike showing susceptibility to heat. This research contributes to the broader scientific understanding of plant stress responses and the combined effectiveness of MYB36 and APX-1 genes in crop improvement without disturbing normal nutritional values. The gene integration can serve as a valuable tool in breeding programs aimed at developing heat-tolerant wheat varieties. These findings also advance our comprehension of the functions of heat-induced genes and lay the foundation for selecting optimal candidates for in-depth functional studies of heat-responsive MYB36 and APX-1 genes in wheat.

Responses of Wheat (Triticum aestivum) Constitutively Expressing Four Different Monolignol Biosynthetic Genes to Fusarium Head Blight Caused by Fusarium graminearum.

The Fusarium head blight (FHB) pathogen Fusarium graminearum produces the trichothecene mycotoxin deoxynivalenol and reduces wheat yield and grain quality. Spring wheat (Triticum aestivum) genotype CB037 was transformed with constitutive expression (CE) constructs containing sorghum (Sorghum bicolor) genes encoding monolignol biosynthetic enzymes caffeoyl coenzyme A (CoA) 3-O-methyltransferase (SbCCoAOMT), 4-coumarate-CoA ligase (Sb4CL), or coumaroyl shikimate 3-hydroxylase (SbC3'H) or monolignol pathway transcriptional activator SbMyb60. Spring wheats were screened for type I (resistance to initial infection, using spray inoculations) and type II (resistance to spread within the spike, using single-floret inoculations) resistances in the field (spray) and greenhouse (spray and single floret). Following field inoculations, disease index, percentage of Fusarium-damaged kernels (FDK), and deoxynivalenol measurements of CE plants were similar to or greater than those of CB037. For greenhouse inoculations, the area under the disease progress curve (AUDPC) and FDK were determined. Following screens, focus was placed on two each of SbC3'H and SbCCoAOMT CE lines because of trends toward a decreased AUDPC and FDK observed following single-floret inoculations. These four lines were as susceptible as CB037 following spray inoculations. However, single-floret inoculations showed that these CE lines had a significantly reduced AUDPC (P < 0.01) and FDK (P ≤ 0.02) compared with CB037, indicating improved type II resistance. None of these CE lines had increased acid detergent lignin compared with CB037, indicating that lignin concentration may not be a major factor in FHB resistance. The SbC3'H and SbCCoAOMT CE lines are valuable for investigating phenylpropanoid-based resistance to FHB.

Precision management influences productivity and nutrients availability in dryland cropping system

AbstractPrecision management (PM) aims to reduce inputs while increasing land productivity and economical return and enhancing cropping system resiliency to climate change. This study evaluated how climate (precipitation) and management influenced yields and soil nutrients in a dryland agricultural system. We compared an “aspirational” (ASP) system (no‐till, 4‐year rotation of winter wheat [Triticum aestivum L.], corn [Zea mays L.], proso millet [Panicum miliaceum L.], and fallow/flex) to a traditional “business‐as‐usual” (BAU) system (reduced tillage, 2‐year rotation of winter wheat and fallow: W–F). Phases of each rotation were included yearly throughout the study period (2018–2022) with three replications. The ASP system incorporated PM by dividing each ASP field into three zones (high‐, medium‐, and low‐PM) according to prior yield and topography. Nitrogen was applied at high, medium, or low application rates within those zones. Under favorable precipitation, wheat, corn, and millet yields responded to PM treatments, with yields increasing proportional to N addition. Years with low in‐season precipitation had a significant reduction in wheat and corn yields (2020 and 2022) and complete millet yield failures (2020 and 2021). Low soil organic matter accumulation (0.1%–0.5%) and a reduction in soil macro‐ and micronutrient status suggested that soil nutrient additions are needed to prevent soil‐nutrient degradation. The ASP treatment added a third crop every 4 years and did so without significantly decreasing wheat yield following fallow. The ASP management shows promise as an alternative to BAU in the Great Plains dryland production region.

Effects of climate change and deep fertilization on the growth and yield of winter wheat in the Loess Plateau of China.

Global temperature is projected to rise continuously under climate change, negatively impacting the growth and yield of winter wheat. Optimizing traditional agricultural measures is necessary to mitigate potential winter wheat yield losses caused by future climate change. This study aims to explore the variations in winter wheat growth and yield on the Loess Plateau of China under future climate change, identify the key meteorological factors affecting winter wheat growth and yield, and analyze the differences in winter wheat yield and root characteristics under different fertilization depths. Meteorological data from 20 General Circulation Models were applied to drive the Decision Support System for Agrotechnology Transfer model, simulating the future growth characteristics of winter wheat under various fertilization depths. The Random Forest model was used to determine the relative importance of meteorological factors influencing winter wheat yield, root length density and leaf area index. The results showed that temperature and high emission concentration were primary factors influencing crop yield under future climate change. The temperature increase projected from 2021 to 2100 would be anticipated to shorten the phenology period of winter wheat by 2-16 days and reduce grain yield by 2.9-12.7% compared to the period from 1981 to 2020. Conversely, the root length density and root weight of winter wheat would increase by 1.2-10.9% and 0.2-24.1%, respectively, in the future, and excessive allocation of root system resources was identified as a key factor contributing to the reduction in winter wheat yield. Compared with the shallow fertilization treatment (N5), the deep fertilization treatments (N15 and N25) increased the proportion of roots in the deep soil layer (30-60 cm) by 2.7-10.2%. Because of the improvement in root structure, the decline in winter wheat yield under deep fertilization treatments in the future is expected to be reduced by 1.2% to 6.5%, whereas water use efficiency increases by 1.1% to 2.4% compared to the shallow fertilization treatment. The deep fertilization treatment can enhance the root structure of winter wheat and increase the proportion of roots in the deep soil layer, thereby effectively mitigating the decline in winter wheat yield under future climate change. Overall, optimizing fertilization depth effectively addresses the reduced winter wheat yield risks and agricultural production challenges under future climate change. © 2024 Society of Chemical Industry.

Prairie soil improves wheat establishment and accelerates the developmental transition to flowering compared to agricultural soils.

Less than 1% of native prairie lands remain in the United States. Located in eastern Washington, the rare habitat called Palouse prairie was largely converted to wheat monocropping. With this conversion came numerous physical, chemical, and biological changes to the soil that may ultimately contribute to reduced wheat yields. Here, we explored how wheat (Tritcum aestivum L.) seedling establishment, plant size, and heading, signifying the developmental transition to flowering, were affected by being planted in prairie soil versus agricultural soils. We then sought to understand whether the observed effects were the result of changes to the soil microbiota due to agricultural intensification. We found that prairie soil enhanced both the probability of wheat seedling survival and heading compared to agricultural soil; however, wheat growth was largely unaffected by soil source. We did not detect effects on wheat developmental transitions or phenotype when inoculated with prairie microbes compared with agricultural microbes, but we did observe general antagonistic effects of microbes on plant size, regardless of soil source. This work indicates that agricultural intensification has affected soils in a way that changes early seedling establishment and the timing of heading for wheat, but these effects may not be caused by microbes, and instead may be caused by soil nutrient conditions.

LWSDNet: A Lightweight Wheat Scab Detection Network Based on UAV Remote Sensing Images

Wheat scab can reduce wheat yield and quality. Currently, unmanned aerial vehicles (UAVs) are widely used for monitoring field crops. However, UAV is constrained by limited computational resources on-board the platforms. In addition, compared to ground images, UAV images have complex backgrounds and smaller targets. Given the aforementioned challenges, this paper proposes a lightweight wheat scab detection network based on UAV. In addition, overlapping cropping and image contrast enhancement methods are designed to preprocess UAV remote-sensing images. Additionally, this work constructed a lightweight wheat scab detection network called LWSDNet using mixed deep convolution (MixConv) to monitor wheat scab in field environments. MixConv can significantly reduce the parameters of the LWSDNet network through depthwise convolution and pointwise convolution, and different sizes of kernels can extract rich scab features. In order to enable LWSDNet to extract more scab features, a scab feature enhancement module, which utilizes spatial attention and dilated convolution, is designed to improve the ability of the network to extract scab features. The MixConv adaptive feature fusion module is designed to accurately detect lesions of different sizes, fully utilizing the semantic and detailed information in the network to enable more accurate detection by LWSDNet. During the training process, a knowledge distillation strategy that integrates scab features and responses is employed to further improve the average precision of LWSDNet detection. Experimental results demonstrate that the average precision of LWSDNet in detecting wheat scab is 79.8%, which is higher than common object detection models and lightweight object detection models. The parameters of LWSDNet are only 3.2 million (M), generally lower than existing lightweight object detection networks.

Probabilistic analysis of drought impact on wheat yield and climate change implications

Drought is projected to intensify under warming climate and will continuously threaten global food security. Assessing the risk of yield loss due to drought is key to developing effective agronomic options for farmers and policymakers. However, little has been known about determining the likelihood of reduced crop yield under different drought conditions and defining thresholds that trigger yield loss at the regional scale in Australia. Here, we estimated the dependence of yield variation on drought conditions and identified drought thresholds for 12 Australia's key wheat producing regions with historical yield data by developing bivariate models based on copula functions. These identified drought thresholds were used to investigate drought statistics under climate change with an ensemble of 36 climate models from Coupled Model Intercomparison Project Phase 6 (CMIP6). We found that drought-induced yield loss was region-specific. The drought thresholds leading to the same magnitude of wheat yield reduction were smaller in regions of southern Queensland and larger in Western Australia mainly due to different climate and soil conditions. Drought will be more frequent and affect larger areas under future warming climates. Based on our results, we advocate for more effective crop management options, particularly in regions where wheat yield is vulnerable to drought in Australia. This will mitigate potential drought impacts on crop production and safeguard global food security.

Nutrient-coated urea mitigates deleterious impacts of salinity and supports wheat performance by enhancing antioxidant activities, photosynthetic performance and nitrogen use efficiency

Soil salinization has increased over recent years and is negatively affecting crop productivity. Nutrient application is an effective strategy to improve abiotic stress tolerance in crops. The application of coated fertilizers has emerged as an excellent approach to mitigate the adverse impacts of soil salinity. Therefore, the present study was conducted to determine the effects of zinc and sulfur coated urea on the performance of wheat growing under saline conditions. The study comprised of diverse salinity stress levels; 0, 6 and 12 dS m−1, cross combined with normal urea (NU), zinc coated urea (ZCU) and sulfur coated urea (SCU). Salinity stress reduced wheat yield by impairing leaf water status, reducing photosynthetic pigments, osmolytes accumulation, potassium (K) and nitrogen (N) uptake while increasing sodium (Na) and chloride (Cl) uptake and hydrogen peroxide (H2O2), malondialdehyde (MDA) and electrolyte leakage (EL) accumulation. The application of ZCU increased the wheat yield by enhancing photosynthetic pigments, leaf water status, antioxidant activities, osmolytes accumulation, and reducing H2O2, MDA and EL accumulation. Furthermore, the significant increase in growth and yield of wheat with ZCU and SCU was also linked with improved K and N uptake, higher nitrogen use efficiency (NUE) and reduced Na and Cl concentration. Thus, the application of ZCU could be an effective approach to improve wheat productivity under saline conditions.

Integrated nitrogen fertilizer management for improving wheat yield and the efficiency of water and nitrogen fertilizer use

Improving resource use efficiency through optimized nitrogen (N) management is the key to increasing crop productivity, but it remains unclear whether integrated N management practices could better improve wheat yield and the use of N and water. Here we investigated the effects of individual and integrated N management practices on wheat production in different soil-climatic conditions, and constructed the relationship between the soil-climate factors and N application rate on wheat yield. Results showed that individual N management practice (optimized N application rate only) reduced wheat yield by 2.4 %, increased N use efficiency (NUE) by 45 %, and decreased water use efficiency (WUE) by 2.2 %; however, integrated N management practice (integrating optimized N rate with irrigation, tillage, manure, or straw return) increased yield and NUE on average by 5.4 % and 55 % respectively, without reducing WUE. In different soil-climate conditions, individual N management practice decreased wheat yield from 1.1 % to 5.0 %; however, integrated N management practice increased yield by 8.5 %, 6.4 %, and 5.8 % in soil organic carbon (SOC) ≥ 10 g kg−1, mean annual precipitation ≤ 400 mm, and 10 °C < mean annual temperature ≤ 15 °C, respectively. Mixed-effects model showed that the integrated N management practice had a higher yield by better exploiting the yield-enhancing benefits of SOC. Facing the complex production environment of the future, applying integrated N management practice will be a key alternative for improving grain production and resource use efficiency.

Resistance of bread wheat (Triticum aestivum L.) varieties to fusarium head blight (Fusarium graminearum) in Ethiopia

AbstractFusarium head blight (FHB) is a devastating disease reduces wheat yield and quality. This study was aimed to evaluate wheat varieties' responses to spray inoculation with Fusarium graminearum mixture isolates under greenhouse conditions. The treatments were laid out in a randomized completely block design with three replications using 24 bread wheat varieties registered in Ethiopia. The varieties inoculated with mixed inoculum derived from four pathogenic isolates of F. graminearum that had been isolated from wheat kernels. Disease severity was evaluated using a 1–9 scale based on the proportion of bleached spikelets, and the area under disease progress curve (AUDPC) was determined from the disease severity data. At harvest, the kernel weight reduction was determined in comparison to the control. The evaluated traits were significantly interrelated and showed high and significant variation among (p &lt; 0.0001) wheat varieties. Disease severity index among the varieties varied from 29% to 72%, while AUDPC varied from 326%‐ to 1010%‐days. The disease progress rate of the Kingbird variety inoculated with F. graminearum was the slowest (0.0191 units day−1), whereas Ogolcho had the fastest disease progression rate (0.0581 units day−1). Kingbird, Wane, and Limu were moderately resistant, with lower disease severity, AUDPC, and a reduction in 1000‐grain weight and grain weight per spike. Dereselgne, Dambal, and Ogolcho varieties were highly susceptible, with the greatest grain weight per spike reduction (53.2%, 41.4%, and 37.4%) and 1000‐grain weight reduction (41.5%, 42.8%, and 37.5%), respectively. The results implied that there were different levels of FHB resistance in Ethiopian bread wheat varieties. Although current greenhouse evaluation of varieties gives encouraging results, field testing is required to confirm the current findings.

Summer cover crop and temporary legume-cereal intercrop effects on soil microbial indicators, soil water and cash crop yields in a semi-arid environment

ContextFew studies have investigated summer cover crops as a replacement for bare fallow in semi-arid temperate regions, and summer cover crop impacts on soil biological function, water balances and subsequent winter crop yields in these regions remain largely unknown. ObjectiveThe 4-year field study aimed to determine the consequences of replacing a summer fallow with a summer growing cover crop on soil function, water balances and subsequent winter cash crop yields in a semi-arid region (486 mm mean annual rainfall) of the Australian southern cropping zone. MethodsA canola (Brassica napus)-wheat (Triticum aestivum L.) rotation with summer fallow was compared to the same rotation with either i) a single species (buckwheat, Fagopyrum esculentum L.) summer cover crop; ii) a four-species mixed brassica + cereal summer cover crop or iii) a cropping sequence with a temporary legume intercrop in the wheat phase of the rotation. Cover crop biomass production, soil water to a depth of 90 cm at cash crop sowing, crop yields and soil functional indices were quantified. ResultsCover crops produced 500–700 kg biomass ha−1 in the 2020 and 2021 seasons and 1000–2400 kg biomass ha−1 in 2022. The four-species mixed cover crop significantly lowered soil water (around 30 mm; P < 0.05) at the time of sowing the cash crop compared to the control and resulted in 15% reduction (P = 0.12) in canola seed yield in 2020, but no significant effect of cover crops of soil water and mineral N at sowing, or cash crop yields, were observed in subsequent seasons. In 2021 the temporary vetch intercrop produced > 1000 kg ha−1 biomass over 9 weeks, and led to a (non-significant) 10% wheat yield reduction. There was no significant effect of cover crop or temporary intercrop treatments on soil functions in the 2020 or 2021 seasons, but activities of several soil enzymes (leucine aminopeptidase, arylsulfatase and B-glucosidase; P < 0.05) and water-soluble carbon (P = 0.059) were significantly higher in the summer cover crop plots compared to control and intercrop plots in March 2022 following termination of the cover crops. These changes coincided with a significant increase in saturated hydraulic conductivity in the four-species cover crop plots in March 2022 compared to control plots. ImplicationsThe study did not provide any compelling evidence for benefits of summer cover crops over fallow in the short term (3–4 years). The relatively low cover crop biomass production over the 4-year study suggests summer cover crops are unlikely to substantially improve soil carbon levels in temperate, semi-arid cropping systems.

Impact of climatic factors and poverty on wheat yields via machine learning in a semi-arid region across West Asia.

Abstract Winter-sown wheat is particularly vulnerable to high temperatures in spring. However, little is known concerning the impact of high temperatures and other climatic and non-climatic factors in combination on winter-sown wheat yields in arid and semi-arid regions. Therefore, in this study we investigate the impacts of high temperatures and other climatic indices, including evapotranspiration and aridity index during spring months, and non-climatic factors, including technology improvement and poverty ratio on irrigated and dryland wheat yields. We employed Random Forests a machine learning technique to our long-term data (1980-2010) and annual wheat yields (irrigated and dryland) for 27 provinces of Iran. The results show that technology improvement and poverty ratio are the most important variables which explain irrigated wheat yields variability. Temperatures above 31°C, evapotranspiration and aridity index are the other variables that alter irrigated whet yields in the region during the period 1980-2010. Dryland wheat yields mainly explained by temperatures above 31°C. Poverty ratio, technology improvement, evapotranspiration and aridity index ranked after high temperatures above 31°C, respectively. This study demonstrates that, although, in arid areas technological improvement and irrigation may avoid yield reduction due to high temperatures in spring months, in poor arid areas and dryland systems, high temperatures significantly reduce wheat yields.

Compensatory effect of supplementary irrigation on winter wheat under warming conditions

Global warming may exacerbate cropland soil drought, affect microbial systems, and decrease grain yield. However, the compensatory effects of supplementary irrigation on winter wheat yield and soil microbial communities under increased temperatures have not been fully studied. Here, a three-year field experiment was conducted, to verify the effects of warming treatments (WS: winter and spring warming; FF: flowering and filling period warming) and irrigation (W0: conventional irrigation; W1: supplemental irrigation) on crop-soil systems during the winter wheat growth stages. The results demonstrated that warming measures have significant negative effects on the net assimilation rate of flag leaves and yield formation, which led to a reduction of wheat yield by 14–40%. However, increasing irrigation can compensate for a yield of 9.7–15%. In addition, warming increases the soil temperature and decreases the soil water content, resulting in decreased soil microbial diversity. The effect size (β) = −0.23 to −0.53 for index of phylogenetic diversity (PD) under warming, while β= 0.16 under increased irrigation. The SEM model further showed that supplementary irrigation during anthesis to filling can improve the soil environment and extend the validity of photosynthetic to increase production, which was an important mitigation measure to adapt to the warming climate in wheat production.

Unveiling the Impact of Growth Traits on the Yield of Bread Wheat Germplasm Subjected to Waterlogging

Changes in the climate have led to the occurrence of extreme events that threaten the production of major crops, namely that of bread wheat (Triticum aestivum L.). Waterlogging imposed at the tillering stage can severely affect the yield, but several genotype features may counterbalance the negative impacts on yields. The aim of this work was to evaluate the effect of waterlogging on the number of fertile spikes, kernels per plant, and single kernel weight, as well as to assess the main culm and tiller participation in yields. We also investigated if the growth stages affected by stress would influence such traits. The study was conducted in climatized growth chambers using 23 genotypes from five distinct germplasm groups (Portuguese landraces, varieties with the introduced Italian germplasm, post-Green Revolution varieties with the introduced CIMMYT germplasm, advanced lines from the Portuguese wheat breeding program, Australian varieties). Variability was observed between and within the groups. Ten genotypes performed well under waterlogged conditions, showing promising results. Among these, GR-2 showed a rise in tiller yield, AdvL-3 in both the main culm and tiller yield, and the remaining ones displayed unaltered values in both the main culm and tillers. PL-1, PL-5, GR-1, GR-3, AdvL-2, Austrl-2, and Austrl-4 were able to compensate for the decreases observed for several traits, reaching harvest yield values that were unaffected in both the main culm and tillers. Rises in the tiller yield or in the tillers and main culm, GR-2 and AdvL-3 exhibited either stability or increases in all the studied parameters. Results also suggest a negative correlation between the growth stage reached during waterlogging and the effect of this stress on the number of spikes per plant, plant and tiller yield, kernel per spike (tillers), and single kernel weight (tillers). Our findings may contribute to a better understanding of wheat responses to waterlogging and to the development of solutions that mitigate the socio-economic impacts of 20–50% wheat yield reductions, thereby preserving the daily 20% supply of energy and protein required for human nutrition and global food security.

Effects of applying lime and phosphogypsum in soybean and wheat nutrition

This study aimed to assess the nutritional status of soybean and wheat and the relationship with grain yield and biometric components after lime and phosphogypsum (GY) reapplication. Treatments consisted of two lime application methods, surface liming and incorporated liming, to different levels of base saturation (BS) (44, 70, and 90%), in addition to surface liming to 70% BS associated with a standard dose (70GY1) or double dose (70GY2) of GY. Treatments were applied in 2012 and reapplied in 2016. The results refer to the 2018/2019 soybean season and the 2019 wheat season. Lime + GY treatment increased leaf area, plant height, leaf dry matter, and stem dry matter in soybean but had no effect on specific leaf area (235.4 cm2 g−1), stem diameter (6.08 mm), number of pods per plant (71.7), grain number per plant (165), or thousand grain weight (117 g). Liming to 90% BS reduced leaf manganese contents in both crops and leaf iron content in soybean. GY application improved the calcium status of both crops and the sulfur status of soybean. However, 70GY2 reduced leaf magnesium contents in soybean and wheat. Soil tillage without lime reduced wheat yield by 12% compared with no-till. Soybean yield correlated positively with leaf nitrogen (0.79), leaf phosphorus (0.91), leaf area (0.62), and thousand grain weight (0.65), whereas wheat yield correlated with leaf phosphorus (0.83), calcium (0.75), and sulfur (0.74). For improved soybean and wheat performance, it is preferable to apply lime and GY to the soil surface (70GY1), permanently maintaining no-till practices.