Climate change, food shortage, water scarcity, and population growth are some of the threatening challenges being faced in today’s world. Drought stress (DS) poses a constant challenge for agricultural crops and has been considered a severe constraint for global agricultural productivity; its intensity and severity are predicted to increase in the near future. Legumes demonstrate high sensitivity to DS, especially at vegetative and reproductive stages. They are mostly grown in the dry areas and are moderately drought tolerant, but severe DS leads to remarkable production losses. The most prominent effects of DS are reduced germination, stunted growth, serious damage to the photosynthetic apparatus, decrease in net photosynthesis, and a reduction in nutrient uptake. To curb the catastrophic effect of DS in legumes, it is imperative to understand its effects, mechanisms, and the agronomic and genetic basis of drought for sustainable management. This review highlights the impact of DS on legumes, mechanisms, and proposes appropriate management approaches to alleviate the severity of water stress. In our discussion, we outline the influence of water stress on physiological aspects (such as germination, photosynthesis, water and nutrient uptake), growth parameters and yield. Additionally, mechanisms, various management strategies, for instance, agronomic practices (planting time and geometry, nutrient management), plant growth-promoting Rhizobacteria and arbuscular mycorrhizal fungal inoculation, quantitative trait loci (QTLs), functional genomics and advanced strategies (CRISPR-Cas9) are also critically discussed. We propose that the integration of several approaches such as agronomic and biotechnological strategies as well as advanced genome editing tools is needed to develop drought-tolerant legume cultivars.

Enhancement of resource use efficiencies and crop productivity in sustainable agriculture are important especially in low-input production systems. This experiment was planned to evaluate the performance of maize under different water and nitrogen levels. Three irrigation treatments i.e., I1= three leaf stage (V1), nine leaf stage (V2), tasseling (T) and milking stage (M); I2 = V1, V2, T, M and dough stage (R1), I3= V1, V2, T, M , R1 and blister stage (R2) were applied with 70 mm application depth with different nitrogen application rates i.e., 0 , 150, 200 and 250 kg N ha-1. Results revealed that maximum growth i.e., plant height, leaf area index (LAI), crop growth rate (CGR), cob length and diameter as well as yield and yield components i.e., grains rows/cob, grains/row, grains/cob, grain weight/cob, 100-grain weight, grain yield, biological yield and harvest index, water and nitrogen use efficiencies as well as transpiration and photosynthetic activities were recorded at I3 with 250 kg N ha-1. However, increased irrigation and nitrogen application rates delayed days to tasseling, silking and maturity. Conclusively, six irrigations (I3) with 250 kg N ha-1 can be adopted as the best input levels to get maximum maize yield under semi-arid regions. In future both these inputs may be used as water and nitrogen based agricultural best management practices (BMPs) in regions with similar type of environmental conditions.

Modern cropping is based on relatively high plant density. The improved grain yield per unit area of modern maize (Zea mays L.) hybrids is due to the increased optimum plant population rather than the improved grain yield per plant. High plant density has been widely used to enhance grain yield in maize. Subsequently we review the effect of planting density on physiology, phenology, morphology, nitrogen use efficiency, water use efficiency grain yield information in maize crop. At higher plant populations reduced grain yield also results from the increased pollento-silking interval and the following barrenness. However, it may lead to higher risk lodging hence causing significant yield loss of the crop. Future insights are morphological and physiological basis controlling barren and stalk lodging resistance. How root traits, and anatomy of sheath and stem of maize plants correspond to high plant population and a further study on the physiological and biological basis of organ development that may govern the mechanisms of high plant density would be essential for future research.

Plants react to the environment and to management interventions by undergoing architectural and structural modifications. A field trial was conducted in China in 2016 to study the effects of the plant population on morphological development of the maize canopy. The main objectives of the current study were (i) to characterize the effects of increased plant density on canopy morphology and stalk lodging and (ii) to explore the relationships between organ morphology and stalk lodging. The field experiment was composed of five plant densities (4.5, 6, 7.5, 9, and 15 plants m−2) of three cultivars: Zhengdan 958 (lodging-resistant cultivar), Longping 206 and Jinqiu 119 (lodging-susceptible cultivars). In response to plant densities of all the three cultivars, the lamina and sheath lengths increased in lower phytomers but decreased in upper phytomers. The lamina width and internode diameter decreased for all phytomers in response to plant densities for all the cultivars. The correlation between organ morphology, plant density and stalk lodging was linear. Data obtained from characterization used in this study (that is, canopy morphology, correlation of organ morphology with stalk lodging traits in response to various plant densities for different cultivars, etc.) will be useful in future modeling studies to predict the morphology characteristics of the canopy affected by interplant competition and stalk lodging.

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