Morpho-Physiological Mechanisms of Maize for Drought Tolerance

Abstract

Maize is one of the mostly consumed grains in the world. It possesses a greater potentiality of being an alternative to rice and wheat in the near future. In field condition, maize encounters abiotic stresses like salinity, drought, water logging, cold, heat, etc. Physiology and production of maize are largely affected by drought. Drought has become a prime cause of agricultural disaster because of the major occurrence records of the last few decades. It leads to immense losses in plant growth (plant height and stem), water relations (relative water content), gas exchange (photosynthesis, stomatal conductance, and transpiration rate), and nutrient levels in maize. To mitigate the effect of stress, plant retreats by using multiple morphological, molecular, and physiological mechanisms. Maize alters its physiological processes like photosynthesis, oxidoreductase activities, carbohydrate metabolism, nutrient metabolism, and other drought-responsive pathways in response to drought. Synthesis of some chemicals like proline, abscisic acid (ABA), different phenolic compounds, etc. helps to fight against stress. Inoculation of plant growth-promoting rhizobacteria (PGPR) can result to the gene expression involved in the biosynthesis of abscisic acid which also helps to resist drought. Moreover, adaptation to drought and heat stress is positively influenced by the activity of chaperone proteins and proteases, protein that responds to ethylene and ripening. Some modifications generated by clustered regularly interspaced short palindromic repeat (CRISPR)-Cas9 are able to improve maize yield in drought. Forward and reverse genetics and functional and comparative genomics are being implemented now to overcome stress conditions like drought. Maize response to drought is a multifarious physiological and biochemical process. Applying data synthesis approach, this study aims toward better demonstration of its consequences to provide critical information on maize tolerance along with minimizing yield loss.

Effects of Phloem-Feeding Pest, Dalbulus maidis on Morphological Expression of Drought-Tolerant Traits in Maize

“…Morphological traits that are selected for under drought stress include, but are not limited to, reduced leaf area, high leaf number and short plants, thick stems, short internodes, small tassels, erect leaves, reduced root biomass, and deep root systems with little lateral root branching [13][14][15][16][17]. As water becomes scarce maize reduce transpiration and close stomata to reduce water loss, which may result in reduction in leaf area and leaf rolling [18]. A well-documented physiological response that contributes to drought tolerance in maize is redirection of growth and dry matter accumulation from shoots to roots, which enhances water uptake [13,19,20].…”