Rainfed Wheat Research Articles

Addressing food insecurity: An exploration of wheat production expansion

Wheat plays a crucial role in global food security, serving as a vital food crop that feeds billions of people worldwide. Currently, Russia and Ukraine are responsible for exporting approximately 25% of the world’s wheat, making any issues in these regions a cause for concern regarding global wheat supply. The problems faced in these areas have led to a surge in wheat prices worldwide. Consequently, it becomes necessary to explore alternative regions that can compensate for the decline in wheat production and supply. This study focuses on wheat production and yield in major producing countries, utilizing the GYGA (Global Yield Gap Atlas) protocol for predictions. The findings reveal a global wheat production gap of 270,378,793 tons. Notably, the largest gap in irrigated wheat production exists in countries like China, India, Pakistan, Turkey, Iran, Afghanistan, Uzbekistan, Egypt, and Azerbaijan. Additionally, the rainfed wheat production gap on a global scale amounts to 545,215,692 tons, with Russia, the USA, Kazakhstan, Australia, Ukraine, China, Turkey, Canada, India, and France having the most significant production gaps. Through boundary line analysis, specific criteria were identified for suitable areas of irrigated and rainfed wheat cultivation. For irrigated conditions, the temperature range of 3000 to 7000 GDD (Growing Degree Days) and a temperature seasonality of 3 were determined as favorable. Under rainfed conditions, the suitable areas encompass a temperature range of 2000 to 4000 GDD, an aridity index exceeding 600, and a temperature seasonality of 2. Thirteen countries possess extensive agricultural land within the climatic codes favorable for irrigated wheat cultivation. Approximately 50% of the agricultural lands within these countries, corresponding to the total arable area for irrigated wheat, fall within the climatic codes 3403, 5403, 5303, 4303, 5503, 5203, 3503, 3303, and 4103. China, the United States, Ukraine, Russia, and Iran are the top five countries with favorable lands for irrigated wheat cultivation. Similarly, fourteen countries have significant agricultural lands within the favorable climatic codes for rainfed wheat cultivation. Around 52% of the agricultural lands within these countries are within the climatic codes 3702, 2702, 2802, and 4602. France, Germany, Britain, Poland, and Denmark possess the highest potential to expand rainfed wheat cultivation areas within these favorable climate codes, with respective areas of 2.7, 2.6, 1.6, and 0.9 million hectares. According to the study, the North China Plain emerges as a primary region for increasing irrigated wheat production, both in terms of cultivated area and yield potential. For rainfed conditions, the European continent stands out as a significant region to enhance wheat production.

Straw Residual Retention on Wheat Photosynthetic Characteristics, Utilization of Water and Nitrogen, and Reactive Nitrogen Losses

Straw residual retention is an emerging and promoted practice in rain-fed northwest China, but its effect on wheat photosynthetic characteristics, the utilization of water and nitrogen, and reactive nitrogen losses is poorly understood. A two-year consecutive field experiment was conducted to investigate the impacts of residual incorporation into soil and nitrogen application on wheat nitrogen and water utilization, yield and nitrogen losses during 2018–2020. The split-plot design of two tillage systems [conventional tillage (CT), and straw residue incorporated into soil (SR)] and three nitrogen rates [0 kg ha−1 (N0), 144 kg ha−1 (N144), 180 kg ha−1 (N180)] was implemented. Our results demonstrated that compared to CT, SR significantly influenced several key metrics. Compared with CT, SR increased the wheat photosynthetic rate (Pn), transpiration rate (Tr), leaf area index (LAI), leaf total chlorophyll (Chl-total), glutamine synthetase (GS) and nitrate reductase (NR) by an average of 5.38%, 12.75%, 8.21%, 5.79%, 16.21% and 20.08%, respectively (p < 0.05). In addition, SR increased the wheat grain yield and nitrogen uptake accumulation (NUA), evapotranspiration (ET), precipitation storage efficiency (PSE), and mineral nitrogen residual after harvest (except for SR-N180 in 2019–2020), but decreased the apparent nitrogen recovery when compared with CT. However, there was an insignificant difference in the ammonia (NH3) volatilization and nitrous oxide (N2O) emissions of SR and CT. With an increase in the N-fertilization rate, the Pn and Tr, NH3 volatilization, N2O emission, mineral nitrogen residual (except for SR-N180 in 2019–2020), LAI, Chl-total (except for SR-N180 and CT-N180 in 2018–2019), GS, NR, grain yield, WUE, and NUA increased significantly; however, the ET, PSE, apparent nitrogen recovery (ANR), and nitrogen harvest index (NHI) decreased significantly. Furthermore, the differences between N144 and N180 in terms of the photosynthetic characteristics of wheat, the utilization of water and nitrogen, and yield were not significant. Overall, straw retention with N144 could be recommended as a resource-saving and environment-friendly management practice in a rain-fed winter wheat–fallow cropping system in northwest China.

Combination of seed priming and nutrient foliar application improved physiological attributes, grain yield, and biofortification of rainfed wheat.

Seed priming and foliar application are two crop management practices that can increase grain yield and quality. The research aimed to assess the influence of seed priming and foliar application on rainfed wheat. Two field experiments with two seed priming rates (control and priming) and five foliar applications [control, urea (4%), silicon (4 mM), FeSO4.7H2O (0.6%), and ZnSO4.7H2O (0.4%)] at the anthesis/Z61 stage were conducted. Seeds were primed for 12h at 25 ± 2°C, by soaking in an aerating solution [urea (20g L-1) + FeSO4.7H2O (50 ppm) + ZnSO4.7H2O (50 ppm) + silicon (20 mg L-1)]. Seed weight-to-solution volume ratio was 1:5 (kg L-1). A pot experiment was also conducted to examine the effect of priming on root growth. Overall, combined seed priming and foliar application induced a positive impact on physiological traits and attributes. Maximum chlorophyll a, chlorophyll b, total chlorophyll, and carotenoid concentrations (1.58, 0.669, 2.24, and 0.61 mg g-1 FW), membrane stability index (77.31%), superoxide dismutase and peroxidase activity (0.174 and 0.375 Unit mg-1 protein), 1,000-grain weight (35.30g), biological yield, grain yield (8,061 and 2,456 kg ha-1), and minimum malondialdehyde concentration (3.91 µg g-1 FW) were observed in seed priming combination with ZnSO4 foliar application. The highest glycine betaine concentration (6.90 mg g-1 DW) and proline (972.8 µg g-1 FW) were recorded with the co-application of seed priming and foliar urea spraying. Foliar application of ZnSO4, FeSO4, and urea drastically enhanced grain Zn (29.17%), Fe (19.51%), and protein content (increased from 11.14% in control to 12.46% in urea foliar application), respectively. Compared to control, seed priming increased root length, root volume, and dry mass root by 8.95%, 4.31%, and 9.64%, respectively. It is concluded that adequate Zn, Fe, silicon, and N supply through seed priming and foliar applications of these compounds at the terminal stage of rainfed wheat alleviates drought stress and improves GY and biofortification.

Determination of Resistance of Winter Wheat Varieties Against Root and Crown Rot Fusarium culmorum Under the Artificial Drought Conditions

This study was conducted to investigate the relationship between the recent increase in the frequency of drought conditions and Root-Crown Rot (Fusarium pseudograminearum, Fusarium culmorum) in rainfed wheat growing areas of Central Anatolia. In 2018, the experiment was established in the greenhouse of Konya Bahri Dağdaş International Agricultural Research Institute using 25 registered wheat varieties in a randomised block split-plot experimental design with 4 replications. Irrigation levels (100% field capacity and 50% field capacity) were designed as main plots, inoculation (+ and -) as subplots and varieties as sub-subplots. In the study, the response of the cultivars to inoculation under artificial drought conditions was evaluated by measuring Crown Score (CR), Lesion Length (LL), Number of Diseased Leaves from outside to inside (NDL) and Plant Height (PH) from five plants in each pot. Statistically, the differences between inoculation, irrigation, NDL and LL were found to be significant at P<0.0001 level, while the differences between varieties were found to be significant at P<0.001 level for the CR parameter. On the other hand, when the interactions were evaluated for the NDL parameter, the differences were found to be significant at P<0.0001 level for all three interactions of cultivar*inoculation, cultivar*irrigation and cultivar*inoculation*irrigation. When the effect of reduced water application intended to be used in resistance breeding was evaluated for 25 different varieties under Fusarium culmorum inoculation, there was an increase in CR from 41,7% (Gerek-79) to 487,5% (Altay-2000), NDL from 7,14% (Kirgiz-95) to 200% (Alpu-2001), LL from -36,84% (Karahan-99) to 283,33% (Altay-2000) and in PH reduction from 12,41% (Seval) to 32,22% (Kirgiz-95). The results showed that drought-stressed plants were already weakened and therefore more easily and severely infected by pathogens. According to these results, it has been determined that it is very important for the region to obtain resistance to drought and crown rot diseases, which have such an obvious relationship, in breeding studies.

Manure substitution with appropriate N rate enhanced the soil quality, crop productivity and net ecosystem economic benefit: A sustainable rainfed wheat practice

Partial substitution of organic fertilizer is adopted to increase production and alleviate farmland greenhouse gas (GHG) emissions. However, there is a lack of integrated assessment of soil quality, crop productivity, and environmental benefits through organic fertilizer substitution. Therefore, an in-situ experiment was conducted with the single nitrogen (N) treatments (120, 180, 240 kg N ha−1, expressed with N120, N180, N240, respectively) and partial substitution with manure fertilizer (each N treatment decreased by 30 kg N ha−1 and plus 2 t ha−1 pig manure, expressed with NM120, NM180, NM240, respectively) for rainfed wheat production on the Loess Plateau. A comparison between N and NM treatments showed that manure substitution treatments: 1) increased soil quality index by 50.9 − 57.4%, grain yield by 9.0 − 42.9%, total N accumulation by 8.6 − 31.1% and nitrogen recovery efficiency by 10.7 − 76.9%; 2) decreased N2O emission by 10.6 − 15.3% and CH4 uptake by 2.9 − 3.6%, whereas increased CO2 emission by 5.1 − 6.7%; 3) reduced the carbon footprint by 1.7 − 2.3 time mainly by the soil organic carbon sequestration. The global warming potential (GWP), Greenhouse gas emission intensity (GHGI), grain yield and net ecosystem economic benefit (NEEB) increased as the fertilizer rates increasing. NM180 had higher yield (average 6022 kg ha−1) and lower GWP (16489 kg CO2-eq ha−1) than N180, which obtained the smaller GHGI (2.67 kg CO2-eq kg−1) and maximum NEEB (4150 RMB ha−1). Overall, manure partial substitution with appropriate N rate enhances soil quality, crop productivity and environment benefit, which is a sustainable rainfed wheat practice.

Probabilistic climate risk assessment in rainfed wheat yield: Copula approach using water requirement satisfaction index

The trend of population growth and the consequent need to increase agricultural production in order to provide for the necessary food is critical topic nowadays. To account for the risks and damage caused by changes in weather and climate constrains, it is important to know how these changes affect the agricultural productivity. Wheat is the world's most widely grown crop and is directly related to worldwide food security issues. As a result, it has always been of interest to researchers as a strategic crop. In this study, the correlation of the Water Requirement Satisfaction Index in six growing periods of rainfed wheat with its yield was examined and found that the highest correlation is seen over the entire growing season. Based on statistical distributions and copula functions, the sensitivity and rainfed wheat yield to the Water Requirement Satisfaction Index was examined. Clayton Copula was selected based on AIC and RMSE evaluation indices. The probability of having crop losses is around 50%, in general. The results showed that the yield risk of rainfed wheat in the Tabriz region drops to 46% under low climatic risk conditions and reaches to 98% under medium and high climate risk conditions. The results allow farmers and stakeholders to better plan and manage food security by knowing the changes in rainfed wheat yield depending on weather conditions. By using different options under different conditions such as wet events, it is also possible to work towards higher yield amounts of rainfed wheat and other rainfed crops.

Modeling the potential impacts of climate change on wheat yield in Iran: Evidence from national and provincial data analysis

Wheat is one of the essential food resources, and its cultivation is one of Iran's most vulnerable activities to climate change. In this context, this study aims to unravel the effects of climate change on both irrigated and rain-fed types of wheat yield in Iran and across different regions to provide valuable insights to researchers, policymakers, and farmers. The study will assist in comprehending the adaption and spatial difference effects of climate change on wheat yield. For this purpose, provinces were classified into two climate types based on the De Martonne Aridity Index. The Feasible generalized least squares model was then employed to data from 28 Iranian provinces over the period 2001 to 2019. The index results show that most provinces are in the arid climate group, while the rest are in the semi-arid group. Our findings for the country indicated that changes in climate factors could have positive and negative effects on wheat yield, with results varying by region. Both wheat varieties are acclimated to climate change's effects, and the coefficients of climate factors from 2001 to 2019 are smaller than those from 2008 to 2019. Conversely, semi-arid provinces' irrigated and rain-fed wheat yields were not adapted to the impact of temperature and participation level changes, while irrigated and rain-fed wheat yields were adapted to carbon emissions. In arid provinces, temperature coefficients for rain-fed wheat yield increased from -1.68 to -2.90, while for irrigated type, coefficients decreased from -0.32 to -0.22. The yield of irrigated wheat has not adapted to changes in carbon emissions and precipitation levels. The study's findings can be useful to policymakers and farmers as they plan and alter crop farming to adapt to the effects of changing climate conditions.

Global insight into understanding wheat yield and production through Agro-Ecological Zoning

Global food security requires food production to be increased in the future decades. Agro-Ecological Zones (AEZ) methodology is a successful approach used in land evaluation studies to support sustainable agricultural development. This approach can facilitate finding suitable areas for wheat production on a global scale. This study was conducted based on a climate zone map, soil data, wheat cultivation area, yield, and production under irrigated and rainfed conditions, worldwide. The results for irrigated wheat indicated that there is an area of 59.5 Mha with an average yield of 4.02 t/ha which leads to the production of about 239.6 Mt of grain yield. Furthermore, climate zones (CZs) of 8002, 5203, 5302, 5403, and 8102 have the highest wheat production with an average of 20.7, 14.2, 13.3, 11.8, 11.5 Mt, respectively. The highest amount of irrigated wheat production has been achieved in soil type code 17 (Loam LF120), which has a cultivation area of around 23.6 Mha and a production of about 106.8 Mt. Rainfed wheat production is 410 Mt, and the cultivation area is 160.2 Mha. The highest rainfed wheat production with an average of 17 Mt was related to the 3702 CZ, followed by the other CZs (3802, 1303, 1203, 3602, 4602, etc.). The soil codes 11 (Loam HF120), 10 (Loam HF180), and 14 (Loam MF120) showed the highest rainfed wheat production. The findings of this study can be useful for agricultural scientists, authorities, and decision-makers around the world to find suitable lands to expand wheat cultivation and also to find new locations for increasing global wheat production to feed the increasing population in the world.

On-farm assessment of agronomic performance of rainfed wheat cultivars under different tillage systems

Evaluation of new cultivars for the agronomic performance under actual on-farm conditions is a highly recommended method for assessing the performance and stability of new cultivars in variable environments and under different management practices. The main purpose of this study was to evaluate the performance and agronomic characteristics of new wheat cultivars in on-farm conditions using different tillage systems to provide suggestions to help the improvement programs and increase the farmers' crop productivity from cropping systems and new cultivars. Seven wheat cultivars, including three bread wheat and four durum wheat cultivars, were evaluated under three tillage systems, including conventional tillage (CT), reduced tillage (RT), and no-tillage (NT) in farmers' fields conditions across two locations and three cropping seasons (2018–21). The results indicated that some of the traits were mainly explained by the genotype effect (thousand kernel weight, heading date and NDVI), while some others by the management practices (grain yield), some by the location (grain yield, spike density, heading date) and year (grain yield, TKW, NDVI, spike density, heading date) effects. Across years and locations, the highest productivity was recorded under CT (2603 kg/ha) followed by RT (2378 kg/ha) and NT (2295 kg/ha), indicating about 13% and 10% superiority production under CT compared with NT and RT, respectively. The wheat cultivars showed different responses to tillage systems, showing the performance of genotypes varied between tillage systems. The Shalan and Eminbey varieties did not interact with tillage systems, but other genotypes significantly differed in their adaptation to tillage systems. The highest mean yield was recorded for the Saji cultivar (durum wheat) under RT (2310 kg/ha), while the Shalan cultivar (bread wheat) performed well in NT (2058 kg/ha), and Saji, Imren, Zahab (durum wheat), and Rijaw and Paraw (bread wheat) had the highest yield under CT. According to GGE biplot analysis, the Shalan and Eminbey varieties had superior performance across on-farm trials, suggesting that they have a broad adaptation to diverse environments. The results identified genotypes with both specific and general adaptions to tillage systems in farmers' fields, that could be explored for increasing productivity and stability under rainfed conditions. Conservation agriculture principles must be incorporated into current wheat breeding program under CT system, to use wheat genetic diversity for conservation agriculture conditions to keep pace food insecurity.

Genotype and agronomic management interaction to enhance wheat yield and water use efficiency in the Mediterranean rainfed environment of Morocco: I. Field data analysis

Durum wheat (Triticum turgidum subsp. durum), considered better drought tolerant, is the most cultivated wheat in Morocco and in the Middle East and North Africa (MENA) region. The region, including Morocco, predominantly has rainfed production systems, declining water supply, and increasing trends and effects of rainfall variability and climate extremes leading to poor crop yield and yield stability. The objectives of this study were to understand major factors determining wheat yield and water use efficiency (WUE); assess the interaction of genotype × environment × management on crop yield and field- and crop-water use efficiencies; and determine the water-limited yield gaps of genotypes under different agronomic management practices in the Mediterranean climate of Morocco. Four years (2015/16–2018/19) of on-station experiments investigating genotype (ten genotypes including seven advanced line and three commercial varieties), seeding time (17 November vs. 29 December), and water management (rainfed vs. supplementary irrigation), was conducted at Merchouch research station, Morocco. The results showed that durum wheat yield mostly varied due to year (rainfall) by 43%, followed by water management × year (23%), year × seeding time (15%), and genotype (7%), with the highest yield (7.15 t ha−1) observed in 2018 (wet year) and the lowest in 2019 (dry year). Across years, not only the rainfall amount but also its distribution during the crop growing season caused yield variability. In low-rainfall years, supplementary irrigation (28–166 mm) increased yield by 2.12–3.27 t ha−1 compared to rainfed conditions. The significant (p < 0.01) year × seeding time × genotype effect on grain yield and WUEs indicates that the response of genotype and seeding time varied with rainfall amount and distribution as the water-limited yield gap in rainfed conditions appeared to be more than 2 t ha−1. In both supplementary irrigated and rainfed systems, the machine learning model showed the effect of different climatic (rainfall and temperature) and management (seeding time, genotype, and irrigation) factors determining yield, yield attributes, and WUEs. The total rainfall remained the most important factor explaining variation in rainfed wheat yield followed by the temperature at flowering, mid- and early-season rainfall, and genotype in order of importance. Similarly, seasonal rainfall was the most important factor explaining variation in grain yield followed by early-season rainfall, days to flowering, temperature at flowering, irrigation amount, seeding time, and genotype in supplementary irrigated durum wheat. Our study clearly shows that yield is highly related to rainfall in rainfed drylands, and the selection of high WUE variety and crop management practices are the key to improving the resilience and sustainability of durum wheat in Morocco and similar production environments in the MENA region.

Integrative effect of activated biochar to reduce water stress impact and enhance antioxidant capacity in crops

Biochar is a soil amendment that can change soil's physical and hydraulic properties. However, biochar application is far from being a ‘one size fits-all’ approach. The impact of the management practices is dependent on biochar type (feedstock and production conditions), application depth and method, climate and site characteristics. Hence, this study aims to enrich the available inconclusive information on how biochar could affect clay loamy soil and to assess the potential impact of the induced change on water stress mitigation of rain-fed durum wheat under the specific condition of the semi-arid environment of North West of Tunisia. A field experiment was investigated in which three biochar rates 0 (B0), 10 (equivalent to 0.5% of weight) (B1) and 20 t/ha (equivalent to 1% of weight), (B2), were tested. Other laboratory analysis allowed the evaluation of soil water retention curve (SWRC), saturated hydraulic conductivity (Ks), dry density (ρb) and biostress biomarkers such as glutathione-S-transferase (GST), catalase activities (CAT) and malondialdehyde content (MDA) as well as yield attributes. Results showed that treatment B2 significantly decreased ρb and Ks with relative change values of about −3.1% and −19%. Consequently, SWRC showed a better water retention capacity, mostly from saturation to matric potential value (h) of 33 kPa. Total (TAWC), plant (PAWC) and readily (RAWC) available water contents, significantly increased under B2 with relative changes of +6%, +44% and +44% respectively. Moreover, GST and CAT were also boosted under B2. Consequently, biological and grain yields as well as grain water use efficiency (GWUE) significantly increased. GWUE increased from 0.81 ± 0.04 in B0 to 1.09 ± 0.01 kg/m3 in B2. The correlation analysis showed a significant and positive correlation, between GWUE and soil water parameters (θs, θfc and θmre) suggesting the indirect effect of biochar on water-use efficiency for grain yield of wheat. Therefore, among the tested rates 20 t/ha could be suggested to improve plant soil water availability and reduce the harmful impact of drought stress on rain-fed durum wheat.

Sustainability of a Rainfed Wheat Production System in Relation to Water and Nitrogen Dynamics in the Soil in the Eyre Peninsula, South Australia

Rainfed wheat production systems are usually characterized by low-fertility soils and frequent droughts, creating an unfavorable environment for sustainable crop production. In this study, we used a processed-based biophysical numerical model to evaluate the water balance and nitrogen (N) dynamics in soils under rainfed wheat cultivation at low (219 mm, Pygery) and medium rainfall (392 mm, Yeelanna) sites in south Australia over the two seasons. Estimated evapotranspiration components and N partitioning data were used to calibrate and validate the model and to compute wheat’s water and N use efficiency. There was a large disparity in the estimated water balance components at the two sites. Plant water uptake accounted for 40–50% of rainfall, more at the low rainfall site. In contrast, leaching losses of up to 25% of seasonal rainfall at the medium rainfall site (Yeelanna) indicate a significant amount of water evading the root zone. The model-predicted N partitioning revealed that ammonia–nitrogen (NH4–N) contributed little to plant N nutrition, and its concentration in the soil remained below 2 ppm throughout the crop season except immediately after the NH4–N-based fertilizer application. Nitrate–nitrogen (NO3–N) contributed to most N uptake during both seasons at both locations. The N losses from the soil at the medium rainfall site (3.5–20.5 kg ha−1) were mainly attributed to NH4–N volatilization (Nv) and NO3–N leaching (NL) below the crop root zone. Water productivity (8–40 kg ha−1 mm−1) and N use efficiency (31–41 kg kg−1) showed immense variability induced by climate, water availability, and N dynamics in the soil. These results suggest that combining water balance and N modeling can help manage N applications to optimize wheat production and minimize N losses in rainfed agriculture.

Fog water harvesting potential and its use in supplementary irrigation of rainfed crops (winter wheat) in Abi-beyglu, Ardabil (Iran)

Abstract In arid and semi-arid areas where available water resources are very limited, the application of unconventional sources of water like the fog is of paramount importance. In this paper, the feasibility of using a standard fog collector (SFC) to collect fog water for complementary irrigation of rainfed wheat in the Abi-beyglu area was investigated. For this purpose, collected water volume was measured on a daily basis during fog time in 2021. The water demand of the winter wheat was estimated by the FAO Penman–Monteith equation under dry and normal conditions. Then the contribution of the collected water to supply the water demand of the wheat and the resultant increase in the yield under two different scenarios, namely complementary irrigation with 30 and 60 mm of collected water, was estimated using the AquaCrop model. Results showed that it is feasible to obtain an average water production of 3.6 L/m2/day over the studied period. Upon irrigation with 30 and 60 mm of collected water under dry and normal conditions, 26 and 34% of the water deficiency for wheat farming was supplied, leading to increased crop yields by 0.6 and 1.7 ton/ha, respectively.

Water stress memory in wheat/maize intercropping regulated photosynthetic and antioxidative responses under rainfed conditions

Drought is a most prevalent environmental stress affecting the productivity of rainfed wheat and maize in the semiarid Loess Plateau of China. Sustainable agricultural practices such as intercropping are important for enhancing crop performance in terms of better physiological and biochemical characteristics under drought conditions. Enzymatic and non-enzymatic antioxidant enzyme activities are associated with improved abiotic tolerance in crop plants, however, its molecular mechanism remains obscure. A 2-year field study was conducted to evaluate the influence of intercropping treatment viz. wheat mono-crop (WMC), maize mono-crop (MMC), intercropping maize (IM) and wheat (IW) crops, and nitrogen (N) application rates viz. control and full-dose of N (basal application at 150 and 235 kg ha−1 for wheat and maize, respectively) on chlorophyll fluorescence, gas exchange traits, lipid peroxidation, antioxidative properties and expression patterns of six tolerance genes in both crops under rainfed conditions. As compared with their respective monocropping treatments, IW and IM increased the Fo/Fm by 18.35 and 14.33%, PS-11 efficiency by 7.90 and 13.44%, photosynthesis by 14.31 and 23.97%, C-capacity by 32.05 and 12.92%, and stomatal conductance by 41.40 and 89.95% under without- and with-N application, respectively. The reductions in instantaneous- and intrinsic-water use efficiency and MDA content in the range of 8.76–26.30% were recorded for IW and IM treatments compared with WMC and MMC, respectively. Compared with the WMC and MMC, IW and IM also triggered better antioxidant activities under both N rates. Moreover, we also noted that intercropping and N addition regulated the transcript levels of six genes encoding non-enzymatic antioxidants cycle enzymes. The better performance of intercropping treatments i.e., IW and IM were also associated with improved osmolytes accumulation under rainfed conditions. As compared with control, N addition significantly improved the chlorophyll fluorescence, gas exchange traits, lipid peroxidation, and antioxidant enzyme activities under all intercropping treatments. Our results increase our understanding of the physiological, biochemical, and molecular mechanisms of intercropping-induced water stress tolerance in wheat and maize crops.

The effect of silicon fertilizers on agronomic performance of bread wheat under drought stress and non‐stress conditions

AbstractDrought is one of the major constraints of wheat production, especially in rainfed wheat production systems. The objective of this study was to evaluate the effects of different silicon fertilizer formulations on the agronomic performance of diverse wheat genotypes under drought‐stressed conditions. Twenty wheat genotypes were evaluated in field and greenhouse environments under non‐stressed and drought‐stressed and two silicon fertilizer formulations (granular and liquid potassium silicate) and untreated control. The four‐way interaction involving genotype, environment, water regime and silicon formulation had a significant effect (p &lt; .05) for aboveground biomass, productive spike number, hundred seed weight and grain yield. Granular silicon application was the most effective treatment both under non‐stressed and drought‐stressed conditions compared to the liquid and control treatments. Under field and drought conditions, the highest yielding genotype was MC18, which exhibited a mean grain yield of 4.17 t ha−1 with granular silicon, 2.56 t ha−1 with liquid silicon and 2.18 t ha−1 without silicon. The yield of genotype MC18 improved by 91.3% using granular silicon under drought‐stressed and by 44.6% under non‐stressed conditions compared with the untreated control. Granular silicon positively affected the drought stress tolerance indices compared to the liquid silicon and untreated control. The principal component biplot analysis revealed that liquid and granular silicon positively impact yield response for all test genotypes under drought‐stressed and non‐stressed conditions compared with the control. Silicon application reduced genotype variation for agronomic traits and enhanced agronomic trait relationships under drought‐stressed conditions. Drought stress tolerance indices are influenced by silicon application. The effect of silicon has a direct and indirect effect on yield and yield components. Silicon fertilization can be considered as a mitigation measure to cope with the adverse effect of drought stress on wheat.

Precision nitrogen management in rainfed durum wheat cultivation: exploring synergies and trade-offs via energy analysis, life cycle assessment, and monetization

Fertilization with variable rate technology (VRT) is a pivotal technique of precision agriculture proposed for eco-friendly farming practices. Yet the magnitude of environmental benefits is often not well known or is highly variable. This study used a multi-indicator model and life cycle-based indicators to compare the performance of rain-fed durum wheat production using uniform (UA) and variable N fertilization (VRT). Two functional units were used: 1 ha of cultivated wheat and 1 ton of wheat produced. The energy analysis indicated that VRT increases energy use efficiency and productivity by 13.3%, reduces specific energy and total energy input by 11.7%, and increases net energy gain by 15.3%. The life cycle assessment (LCA) analysis indicated that for some environmental impacts, VRT had minor negative effects due to the comparable yield performance with UA. Yet, the VRT had a noteworthy positive impact on global warming, fine particulate matter formation, stratospheric ozone depletion, terrestrial acidification, and marine eutrophication, generating a final environmental benefit of 12.2% for 1 ton of product and 13.3% for 1 ha of land. Economic valuation or monetization of LCA results using monetization weighting factors indicated indirect economic benefits of VRT can be up to 6.6% for 1 ton of product and 7.7% for 1 ha of land. Our findings support the use of nitrogen fertilization with VRT for sustainable extensification and improved eco-efficiency of wheat production in a Mediterranean context. As a result of our research, we conclude that future case studies on annual crops with moderate land requirements should employ multiple metrics and functional units, as well as the concepts of monetization and life cycle assessment, to investigate trade-offs between yield, economic, and environmental benefits and to aid decision-making about the true sustainability of proposed farming technologies.Graphical abstract

Moderate organic fertilizer substitution for partial chemical fertilizer improved soil microbial carbon source utilization and bacterial community composition in rain-fed wheat fields: current year.

Organic fertilizers can partially replace chemical fertilizers to improve agricultural production and reduce negative environmental impacts. To study the effect of organic fertilizer on soil microbial carbon source utilization and bacterial community composition in the field of rain-fed wheat, we conducted a field experiment from 2016 to 2017 in a completely randomized block design with four treatments: the control with 100% NPK compound fertilizer (N: P2O5: K2O = 20:10:10) of 750 kg/ha (CK), a combination of 60% NPK compound fertilizer with organic fertilizer of 150 kg/ha (FO1), 300 kg/ha (FO2), and 450 kg/ha (FO3), respectively. We investigated the yield, soil property, the utilization of 31 carbon sources by soil microbes, soil bacterial community composition, and function prediction at the maturation stage. The results showed that (1) compared with CK, organic fertilizer substitution treatments improved ear number per hectare (13%-26%), grain numbers per spike (8%-14%), 1000-grain weight (7%-9%), and yield (3%-7%). Organic fertilizer substitution treatments increased the total nitrogen, available nitrogen, available phosphorus, and soil organic matter contents by 26%, 102%, 12%, and 26%, respectively, compared with CK treatments. Organic fertilizer substitution treatments significantly advanced the partial productivity of fertilizers. (2) Carbohydrates and amino acids were found to be the most sensitive carbon sources for soil microorganisms in different treatments. Particularly for FO3 treatment, the utilization of β-Methyl D-Glucoside, L-Asparagine acid, and glycogen by soil microorganisms was higher than other treatments and positively correlated with soil nutrients and wheat yield. (3) Compared with CK, organic fertilizer substitution treatments increased the relative abundance of Proteobacteria, Acidobacteria, and Gemmatimonadetes and decreased the relative abundance of Actinobacteria and Firmicutes. Interestingly, FO3 treatment improved the relative abundance of Nitrosovibrio, Kaistobacter, Balneimonas, Skermanella, Pseudomonas, and Burkholderia belonging to Proteobacteria and significantly boosted the relative abundance of function gene K02433 [the aspartyl-tRNA (Asn)/glutamyl-tRNA (Gln)]. Based on the abovementioned findings, we suggest FO3 as the most appropriate organic substitution method in rain-fed wheat fields.

Soil nutrition management may preserve non-detrimental weed communities in rainfed winter wheat (T. aestivum)

Overuse of fertilizers has been associated with the selection of competitive and dominant weed communities and biodiversity loss. Considering that crop nutrient management is going through a continuous revisitation process to improve nutrient use efficiency and energy savings, we addressed the consequences of different nutritional levels (low, optimal, and surplus) on weed community composition and wheat growth, yield, and kernel quality. Weed density and biomass were evaluated on sampling areas at the heading stage, and the data obtained were subjected to a cluster analysis for the identification of different weed communities throughout the experimental plots. At harvest, plant growth, yield and quality traits of wheat and wheat kernels were evaluated and correlated with the presence of different weed communities. Out of the four weed communities identified under optimal and low nutrition, two communities did not significantly reduce wheat yield. Under surplus nutrition only one weed community was identified, which resulted to be detrimental for wheat production in terms of yield quantity and quality. The non-detrimental communities were characterized by a high presence of corn chamomile (Anthemis arvensis L.), birdeye speedwell (Veronica persica Poir.), and common chickweed (Stellaria media (L.) Vill). On the contrary, the detrimental communities, were characterized by a high density and aboveground biomass of burr medic (Medicago polymorpha L.). Finally, under surplus nutrition, species richness declined, and the density and aboveground biomass of annual ryegrass (Lolium rigidum Gaud.) increased compared to optimal and low nutrition. Our results showed that soil fertilization plays a crucial role in differentiating detrimental vs. non-detrimental weed communities, with excess fertilization reducing species richness and selecting for competitive and specialized weed species. Overall, an efficient management of soil nutrients may promote non-detrimental weed communities while reducing weed management intensity and thereby improving biodiversity and sustainability. Assessing the efficiency of soil fertilization management and understanding how different fertilization rates and forms may affect weed communities is crucial to advancing sustainable weed management.

Soil Aggregates Stability Response to Summer Fallow Tillage in Rainfed Winter Wheat Fields on the Loess Plateau

Soil aggregates are one of the most important indicators of soil quality, which can be affected strongly by soil tillage. Little is known about the composition and stability of soil aggregates under summer fallow tillage in rainfed winter wheat fields on the Loess Plateau. Soil aggregates were assessed before sowing and after the harvest of winter wheat under three tillage treatments during summer fallow, including minimum tillage (FMT), subsoiling (FST) and plough tillage (FPT). The results showed that the 0.25–2 mm soil mechanical-stable aggregates (MSA) under the FPT treatment were significantly higher (25.5–42.1%) compared with the FMT treatment in the 0–40 cm soil layer before sowing. The FMT treatment significantly increased the 0.5–2 mm size WSA content (24.6–342.4%) compared with the FPT treatment in the 0–20 cm soil layer before sowing and after harvesting. Compared with the FMT treatment, the FPT treatment significantly increased the stability of the MSA in the 0–20 cm soil layer before sowing and the FST treatment significantly increased the stability of the MSA in the 0–50 cm soil layer after harvest. The FPT treatment significantly decreased the geometric mean diameter (4.2–9.3%) and the stability rate (73.6–252.6%) and increased the destruction rate (1.3–3.5%) and the unstable aggregate index of the WSA (0.8–2.3%) in the 0–20 cm soil layer before sowing, compared with the FMT treatment. In summary, the application of FPT and FST increased the stability of the MSA in the 0–20 cm soil layer; however, FMT improved the stability of the WSA in the 0–40 cm soil layer.

Impact of Climate Variables Change on the Yield of Wheat and Rice Crops in Iran (Application of Stochastic Model Based on Monte Carlo Simulation).

This study aims to predict the yield of two strategic crops in Iran; wheat and rice, under climate scenarios that indicate probable changes in climate variables. It implemented by a stochastic model based on the Monte Carlo method. This model were estimated based on historical data from 1988 to 2019 for precipitation and temperature provided possible changes in the pattern of and their probability of occurrence. The results show that rain-fed wheat, irrigated wheat and rice yields decrease by 42%, 29% and 21% respectively in the average scenario. Therefore, policy makers should try to make the right decisions to increase the production of the country's strategic crops. R&D management to introduce drought-tolerant varieties, use of modern irrigation systems and use of low-volume irrigation methods are some of the proposed solutions to mitigate the effects of climate change.