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Drought stress is one of the most detrimental abiotic stresses limiting wheat productivity worldwide. Methyl Jasmonate (MeJA), a stress signaling compound, may be effective in alleviating drought-induced adversities in wheat. Current study examined the role of exogenously applied MeJA in improving drought tolerance in five different wheat cultivars (Yu-Mai-1, Lu-Nong-116, Huai-Mai-19, Yan-Nong-19, Bai-Maizi). Drought stress (35 % field capacity) was imposed either at jointing (DS1), heading (DS2) or grain filling (DS3) stage. A control was maintained at field capacity of 90 % for comparison. The MeJA was applied at 0.5 mM after 1 week after imposition of drought. Data regarding different growth and yield attributes was recorded. Results depicted that drought stress at any growth stage substantially reduced the growth and yield of all wheat cultivars. More severe reductions in plant height, peduncle length, dry biomass (leaves, culm, root), and in yield components were observed in DS1 compared with DS2 or DS3. Exogenous application of MeJA effectively assuaged the damaging effects of drought. Beneficial effects of MeJA on dry biomass, number of grains per spike, and grain weight led to higher grain and biological yield in MeJA–treated plants under drought as well as control conditions. Variations were also apparent among cultivars regarding their response to drought stress. The cultivar Yu-Mai-1 remained superior to rest of cultivars in terms of wheat yield. In summary, our results suggested the involvement of MeJA in improving the drought tolerance of wheat by maintaining growth and yield performance of plants.

Water deficit is perhaps the most severe threat to sustainable crop production in the conditions of changing climate. Researchers are striving hard to develop resistance against water deficit in crop plants to ensure food security for the coming generations. This study was conducted to establish the role of fulvic acid (FA) application in improving the performance of hybrid maize (Zea mays L.) under drought. Maize plants were grown under normal conditions till tasselling and were then subjected to drought by cessation of water followed by foliar application of FA (1.5 mg l−1). Drought stress disrupted the photosynthetic pigments and reduced the gas exchange leading to reduction in plant growth and productivity. Nonetheless, exogenous FA application substantially ameliorated the adversities of drought by sustaining the chlorophyll contents and gas exchange possibly by enhanced levels of antioxidant enzyme (superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT)) activities and proline. These beneficial effects yielded in terms of plant growth and allometry, and grain yield. It is interesting to note that FA application also improved the crop performance under well‐watered conditions. Hence, FA may be applied to improve the crop performance under drought and well‐watered conditions.

Glycinebetaine acts as an osmoprotectant and is closely related with drought resistance. In the present study, glycinebetaine (GB) was exogenously-applied to two contrasting maize cultivars, Dongdan-60 and ND-95, to see whether GB improves drought resistance. Maize cultivars were grown with normal water supply till the heading stage and then exposed to two levels of soil moisture, well-watered control and drought-stressed, and then GB solution of 100 mmol was foliar applied five days after moisture treatments were imposed. The gas exchange and chlorophyll concentration were substantially declined in both maize cultivars under water stressed conditions. However, this reduction was less in Dongdan-60 than ND-95. Nonetheless, GB-treated plants considerably maintained higher gas exchange rate and chlorophyll concentration during drought stress than non-GB treated plants. The GB-induced improvement in gas exchange and chlorophyll synthesis under water stress ultimately resulted in improved growth and yield in both maize cultivars. Furthermore, the positive responses to exogenous GB application were more pronounced in Dongdan-60 as compared to ND-95 in all traits examined under water-deficit con ditions. In conclusion, exogenously applied GB to maize crops could improve gas exchange, chlorophyll synthesis, growth and yield of maize.

Methyl jasmonate (MeJA), a plant-signalling molecule, is involved in an array of plant development and the defence responses. This study was conducted to explore the role of exogenous MeJA application in alleviating the adversities of drought stress in soybean (Glycine max L. Merrill.). Soybean plants were grown under normal conditions until blooming and were then subjected to drought by withholding irrigation followed by foliar application of (50 lm) MeJA. Drought stress substantially suppressed the yield and yield-related traits, whereas it accelerated the membrane lipid peroxidation. Nonetheless, substantial increase in activities of enzymatic antioxidants (superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT)), proline, relative water contents (RWC) with simultaneous decrease in membrane lipid peroxidation was observed in MeJA-treated plants under drought. These beneficial effects led to improvement in biological and grain yield, and harvest index under drought. Interestingly, MeJA application was also useful under well-watered conditions. These results suggest the involvement of MeJA in improving the drought tolerance of soybean by modulating the membrane lipid peroxidation and antioxidant activities.

Brassinolides (BRs) are naturally occurring substances, which modulate plant growth and development events and have been known to improve the crop tolerance to abiotic stresses. In this study, possible role of exogenously applied brassinolide (BR) in alleviating the detrimental effects of drought in maize was evaluated in a rain-protected wire-house. Maize was subjected to drought at the start of tasseling for 6 days by withholding water application followed by foliar spray of BR (0.1 mg l−1) to assess the changes in growth, gas exchange, chlorophyll contents, protein, relative leaf water contents (RLWC), proline, malonialdehyde (MDA) and enzymatic antioxidants. Drought substantially reduced the maize growth in terms of plant height, leaf area and plant biomass. Moreover, substantial decrease in gas exchange attributes (net photosynthetic rate (A), transpiration rate (E), stomatal conductance (gs), water use efficiency (WUE), instantaneous water use efficiency (WUEi) and intercellular CO2 (Ci) was also recorded. However, exogenous application of BR remarkably improved the gas exchange attributes, plant height, leaf area, cobs per plant, seedling dry weight both under drought and well-watered conditions. BR-induced promotion in growth and physiological and metabolic activities were mediated through increased protein synthesis enabling maintenance of tissue water potential and activities of antioxidant enzymes lowering the lipid peroxidation under drought.

An investigation was carried out to examine the combined and individual effects of cadmium (Cd) and arsenic (As) stress on osmolyte accumulation, antioxidant activities, and reactive oxygen species (ROS) production at different growth stages (45, 60, 75, 90 days after sowing (DAS)) of two maize cultivars viz., Dong Dan 80 and Run Nong 35. The Cd (100 μM) and As (200 μM) were applied separately as well as in combination (Cd + As) at 30 DAS. Results revealed pronounced variations in the behavior of antioxidants, osmolytes, and ROS in both maize cultivars under the influence of Cd and As stress. Activities of enzymatic (SOD, POD, CAT and APX, GPX, GR) and non-enzymatic (GSH and AsA) antioxidants, generation of ROS, and accumulation of osmolytes were enhanced with the passage of time; therefore, the maximum values for these attributes were observed at 90 DAS for both cultivars. Exposure of plants to Cd or As stress considerably enhanced the antioxidant activities, ROS, and osmolyte accumulation compared with control, while combined application of Cd + As was more devastating in reducing plant biomass of both maize cultivars. Among cultivars, Dong Dan 80 was better able to negate the heavy metal-induced oxidative damage, which was associated with higher antioxidant activities, greater osmolytes accumulation, and lower ROS production in this cultivar.

Increased cadmium (Cd) accumulation in soils has led to tremendous environmental problems, with pronounced effects on agricultural productivity. Present study investigated the effects of Cd stress imposed at various concentrations (0, 75, 150, 225, 300, 375 μM) on antioxidant activities, reactive oxygen species (ROS), Cd accumulation, and productivity of two maize (Zea mays L.) cultivars viz., Run Nong 35 and Wan Dan 13. Considerable variations in Cd accumulation and in behavior of antioxidants and ROS were observed under Cd stress in both maize cultivars, and such variations governed by Cd were concentration dependent. Exposure of plant to Cd stress considerably increased Cd concentration in all plant parts particularly in roots. Wan Dan 13 accumulated relatively higher Cd in root, stem, and leaves than Run Nong 35; however, in seeds, Run Nong 35 recorded higher Cd accumulation. All the Cd toxicity levels starting from 75 μM enhanced H2O2 and MDA concentrations and triggered electrolyte leakage in leaves of both cultivars, and such an increment was more in Run Nong 35. The ROS were scavenged by the enhanced activities of superoxide dismutase, peroxidase, catalase, ascorbate peroxidase, and glutathione peroxidase in response to Cd stress, and these antioxidant activities were higher in Wan Dan 13 compared with Run Nong 35 at all Cd toxicity levels. The grain yield of maize was considerably reduced particularly for Run Nong 35 under different Cd toxicity levels as compared with control. The Wan Dan 13 was better able to alleviate Cd-induced oxidative damage which was attributed to more Cd accumulation in roots and higher antioxidant activities in this cultivar, suggesting that manipulation of these antioxidants and enhancing Cd accumulation in roots may lead to improvement in Cd stress tolerance.

Based on the survey and experimental results, this paper analyzed the time-sequence relationship between crop growth and rainfall distribution, and the potential water use rate, water supply-demand equilibrium and deficit features of different upland crops in the loess hilly zone of south Ningxia. The model of water ecological adaptability index (WEAI) was proposed to evaluate these features of upland crops. The results showed that autumn crops were superior to summer crops in the coupling characteristics between crop growth and rainfall distribution. There were also differences in rainfall potential use rate among crops, the order being: perennial cropsroot and stem cropsgrain crops; autumn cropssummer crops. The water satiety rate and water ecological adaptability were higher for autumn crops than for summer crops, and higher in rainy years than in dry years. In line with water ecological adaptability index, the 6 main crops could be put in order of milletpotatopanicflaxpeaspring wheat. The results of this study may provide theoretic basis for drawing up the decision scheme of cropping system in upland regions.