Seed Priming and Foliar Application of Chitosan Ameliorate Drought Stress Responses in Mungbean Genotypes Through Modulation of Morpho-physiological Attributes and Increased Antioxidative Defense Mechanism

Drought is one of the important abiotic stress factors that affect crop productivity worldwide. In recent years, applications of biopolymer chitosan on plants have received attention due to their biostimulant activity and ability to elicit a defense response to stress. The current study investigates the effect of seed priming and foliar application, or both, under drought stress in pot experiments. The optimal concentration of chitosan was determined through morpho-physiological attributes and carried forward for seed priming and foliar application under drought stress in pot experiments for two consecutive years. Morpho-physiological, biochemical and yield attributes were investigated in two genotypes of mungbean which were previously screened for drought tolerant and susceptibility. Results revealed that drought stress considerably reduced plant growth parameters, relative water content, and increased oxidative stress markers such as proline, H 2 O 2 and MDA leading to reduced yield attributes. However, chitosan application significantly mitigates these effects. Both seed priming and foliar-applied chitosan in both the genotypes significantly improved all the studied parameters through increased antioxidant enzymes like SOD, CAT and APX in drought stress plants. The combination of both seed priming and foliar application of chitosan most significantly improved drought-induced responses which are reflected through improvement in morpho-physiological, biochemical attributes, increased antioxidative enzyme activities and improved yield in both the tolerant and susceptible genotypes.