• Energy Research

Water scarceness is a major threat to wheat productivity under changing climate scenarios, especially in arid and semi-arid regions. However, growing drought-tolerant wheat genotypes could be a sustainable option to enhance wheat productivity under drought stress conditions. The aim of this study was to evaluate the effect of mild to severe drought stress on gas exchange parameters, relative water content, SPAD-chlorophyll value, and yield-related parameters of 14 wheat genotypes being cultivated in arid to semi-arid areas on large scale. The genotypes were grown in earthen pots under three drought levels, namely (1) control-well watered, (2) mild water stress, i.e., 60% water holding capacity, and (3) severe water stress, i.e., 40% water holding capacity. The drought was imposed from the jointing stage to physiological maturity. Drought significantly decreased net photosynthesis, stomatal conductance, relative water contents, 100-grain weight, and grain yield in all genotypes. However, the reduction percentage was different in different genotypes under drought stress compared with well-watered conditions. The highest relative water content (65.2%) was maintained by the genotype Galaxy-2013, followed by AAS-2011 (64.6%) and Johar-2016 (62.3%) under severe drought conditions. Likewise, Galaxy-2013 showed the highest net photosynthesis and stomatal conductance under severe drought conditions. The highest grain yield per plant (6.2 g) and 100-grain weight (3.3 g) was also recorded in Galaxy-2013 under severe drought conditions, while the highest grain yield under well-watered conditions was recorded in Johar-2016, followed by Galaxy-2013. These results suggest that wheat variety Galaxy-2013 could be cultivated extensively to obtain good wheat yield under limited water conditions.

Water scarceness is a major threat to wheat productivity under changing climate scenarios, especially in arid and semi-arid regions. However, growing drought-tolerant wheat genotypes could be a sustainable option to enhance wheat productivity under drought stress conditions. The aim of this study was to evaluate the effect of mild to severe drought stress on gas exchange parameters, relative water content, SPAD-chlorophyll value, and yield-related parameters of 14 wheat genotypes being cultivated in arid to semi-arid areas on large scale. The genotypes were grown in earthen pots under three drought levels, namely (1) control-well watered, (2) mild water stress, i.e., 60% water holding capacity, and (3) severe water stress, i.e., 40% water holding capacity. The drought was imposed from the jointing stage to physiological maturity. Drought significantly decreased net photosynthesis, stomatal conductance, relative water contents, 100-grain weight, and grain yield in all genotypes. However, the reduction percentage was different in different genotypes under drought stress compared with well-watered conditions. The highest relative water content (65.2%) was maintained by the genotype Galaxy-2013, followed by AAS-2011 (64.6%) and Johar-2016 (62.3%) under severe drought conditions. Likewise, Galaxy-2013 showed the highest net photosynthesis and stomatal conductance under severe drought conditions. The highest grain yield per plant (6.2 g) and 100-grain weight (3.3 g) was also recorded in Galaxy-2013 under severe drought conditions, while the highest grain yield under well-watered conditions was recorded in Johar-2016, followed by Galaxy-2013. These results suggest that wheat variety Galaxy-2013 could be cultivated extensively to obtain good wheat yield under limited water conditions.

Two chickpea genotypes viz. Bhakar-2011 (desi) and Noor-2013 (kabuli) were sown in soil filled pots supplied with low (0.3 mg kg-1) and high (3 mg kg-1 soil) zinc (Zn) under control (70% water holding capacity and 25/20 °C day/night temperature), drought (35% water holding capacity) and heat (35/30 °C day/night temperature) stresses. Drought and heat stresses reduced rate of photosynthesis, photosystem II efficiency, plant growth and Zn uptake in chickpea. Low Zn supply exacerbated adverse effects of drought and heat stresses in chickpea, and caused reduction in plant biomass, carbon assimilation, antioxidant activity, impeded Zn uptake and enhanced oxidative damage. However, adequate Zn supply ameliorated adverse effect of drought and heat stresses in both chickpea types. The improvements were more in desi than kabuli type. Adequate Zn nutrition is crucial to augment growth of chickpea plants under high temperature and arid climatic conditions.

Two chickpea genotypes viz. Bhakar-2011 (desi) and Noor-2013 (kabuli) were sown in soil filled pots supplied with low (0.3 mg kg-1) and high (3 mg kg-1 soil) zinc (Zn) under control (70% water holding capacity and 25/20 °C day/night temperature), drought (35% water holding capacity) and heat (35/30 °C day/night temperature) stresses. Drought and heat stresses reduced rate of photosynthesis, photosystem II efficiency, plant growth and Zn uptake in chickpea. Low Zn supply exacerbated adverse effects of drought and heat stresses in chickpea, and caused reduction in plant biomass, carbon assimilation, antioxidant activity, impeded Zn uptake and enhanced oxidative damage. However, adequate Zn supply ameliorated adverse effect of drought and heat stresses in both chickpea types. The improvements were more in desi than kabuli type. Adequate Zn nutrition is crucial to augment growth of chickpea plants under high temperature and arid climatic conditions.

Salt stress in soils impacts grain crop yield. Soil amendment with biochar and arbuscular mycorrhizal alone has been analyzed to improve the growth of several crops under salinity stress. However, the combined application of biochar and arbuscular mycorrhizal fungi for the remediation of salinity and improvement of crop productivity in wheat are rarely discussed and have remained unclear. Therefore, this experiment was performed to investigate the effect with biochar (150 g biochar per each treated pot containing 3 kg soil) and/or arbuscular mycorrhizal fungi (20 g AMF inoculum containing 80% mycorrhizal roots, 100–160 spores, and extraradical hyphae per each treated pot) on the productivity of wheat (Triticum aestivum L.) under four salt stress gradients; 0, 50, 100, and 150 mM NaCl. The results show salinity significantly reduced plant height (9.9% to 22.9%), shoot fresh weight (35.6% to 64.4%), enzymatic activities (34.1% to 39.3%), and photosynthetic pigments—i.e., total chlorophyll contents (75.0%) and carotenoids contents (56.2%) of plants—as compared with control. Under exclusive biochar application, the plants were moderately tolerant to salinity stress, which was evident in their growth, moderately reduced fatty acid content, partially impaired enzymatic activity, and photosynthetic pigments, while under the exclusive AMF application, the wheat plants were relatively sensitive to salinity stress, resulting in impaired growth rate, decreased unsaturated fatty acid composition, enzymatic activity, and photosynthetic pigments. Conversely, under the co-application of biochar and AMF, wheat plants partially increased plant height (14.1%), shoot fresh biomass (75.7%), root fresh biomass (24.9%), partially increased enzymatic activity (49.5%), and unimpaired photosynthetic pigments (30.2% to 54.8%) of wheat under salinity stress. Current findings concluded that exclusive incorporation of biochar, and the synergistic application of AMF and biochar, could be utilized as a promising way to reduce the deleterious effects of salinity stress in wheat production.

Salt stress in soils impacts grain crop yield. Soil amendment with biochar and arbuscular mycorrhizal alone has been analyzed to improve the growth of several crops under salinity stress. However, the combined application of biochar and arbuscular mycorrhizal fungi for the remediation of salinity and improvement of crop productivity in wheat are rarely discussed and have remained unclear. Therefore, this experiment was performed to investigate the effect with biochar (150 g biochar per each treated pot containing 3 kg soil) and/or arbuscular mycorrhizal fungi (20 g AMF inoculum containing 80% mycorrhizal roots, 100–160 spores, and extraradical hyphae per each treated pot) on the productivity of wheat (Triticum aestivum L.) under four salt stress gradients; 0, 50, 100, and 150 mM NaCl. The results show salinity significantly reduced plant height (9.9% to 22.9%), shoot fresh weight (35.6% to 64.4%), enzymatic activities (34.1% to 39.3%), and photosynthetic pigments—i.e., total chlorophyll contents (75.0%) and carotenoids contents (56.2%) of plants—as compared with control. Under exclusive biochar application, the plants were moderately tolerant to salinity stress, which was evident in their growth, moderately reduced fatty acid content, partially impaired enzymatic activity, and photosynthetic pigments, while under the exclusive AMF application, the wheat plants were relatively sensitive to salinity stress, resulting in impaired growth rate, decreased unsaturated fatty acid composition, enzymatic activity, and photosynthetic pigments. Conversely, under the co-application of biochar and AMF, wheat plants partially increased plant height (14.1%), shoot fresh biomass (75.7%), root fresh biomass (24.9%), partially increased enzymatic activity (49.5%), and unimpaired photosynthetic pigments (30.2% to 54.8%) of wheat under salinity stress. Current findings concluded that exclusive incorporation of biochar, and the synergistic application of AMF and biochar, could be utilized as a promising way to reduce the deleterious effects of salinity stress in wheat production.

Conventional tillage, extreme climate events, increasing weed incidence, pest and disease pressures, and diminished farm input availability negatively impact crop yield, stability, profitability, and water productivity in South Asia's rice-wheat (R-W) systems. This article reviews and evaluates the effectiveness and benefits of conservation agriculture (CA) practices in improving soil health, water productivity, and sustainability in R-W systems. CA practices focus on minimum soil disturbance, permanent soil cover, and crop rotations. Techniques such as direct seeding in rice and zero tillage in wheat are employed, supported by advancements in zero tillage sowing machinery like super-seeders. CA practices contribute significantly to ecosystem health by conserving soil and water, enhancing soil quality, reducing erosion, and improving nutrient use efficiency. They also lower production costs, increase water use efficiency, stabilize yields, promote crop diversification, and mitigate climate change effects through carbon sequestration and reduced greenhouse gas emissions. However, initial challenges include increased weed pressure and the need for suitable rice varieties for direct seeding. In conclusion, CA practices support sustainable and climate-resilient farming, improving land and water productivity, food security, and on-farm profits. Despite the benefits and growing government support, widespread adoption in South Asia remains limited. Effective support systems, including incentives, technical knowledge dissemination, and integrated weed management, are crucial for overcoming barriers and enhancing CA adoption in R-W systems.

Conventional tillage, extreme climate events, increasing weed incidence, pest and disease pressures, and diminished farm input availability negatively impact crop yield, stability, profitability, and water productivity in South Asia's rice-wheat (R-W) systems. This article reviews and evaluates the effectiveness and benefits of conservation agriculture (CA) practices in improving soil health, water productivity, and sustainability in R-W systems. CA practices focus on minimum soil disturbance, permanent soil cover, and crop rotations. Techniques such as direct seeding in rice and zero tillage in wheat are employed, supported by advancements in zero tillage sowing machinery like super-seeders. CA practices contribute significantly to ecosystem health by conserving soil and water, enhancing soil quality, reducing erosion, and improving nutrient use efficiency. They also lower production costs, increase water use efficiency, stabilize yields, promote crop diversification, and mitigate climate change effects through carbon sequestration and reduced greenhouse gas emissions. However, initial challenges include increased weed pressure and the need for suitable rice varieties for direct seeding. In conclusion, CA practices support sustainable and climate-resilient farming, improving land and water productivity, food security, and on-farm profits. Despite the benefits and growing government support, widespread adoption in South Asia remains limited. Effective support systems, including incentives, technical knowledge dissemination, and integrated weed management, are crucial for overcoming barriers and enhancing CA adoption in R-W systems.