EXPLORATION OF MELATONIN-MEDIATED SALT STRESS TOLERANCE IN CONTRASTING GENOTYPES OF VIGNA RADIATA (L.) WILCZEK THROUGH MORPHOLOGICAL, PHYSIOLOGICAL, AND BIOCHEMICAL CHARACTERIZATION

Abstract

Salinity is a significant abiotic factor reducing the productivity of mungbeans; melatonin turned out as a plant stress tolerance regulating factor. In the current study, 12 Vigna radiata genotype were tested for salt-stress tolerance and the effect of pre-treating with melatonin (exogenous). The various genotypes were evaluated under control, NaCl stress (50 mM), melatonin supply (100 µM) and NaCl + melatonin. Morphological and yield attributes and germination was evaluated to screen the genotype and detailed physiological, biochemical and phenolic characterization of two contrasting genotypes ML2056 and ML1808 was done. Salinity decreased all the other traits including germination, biomass, yield parameters, chlorophyll, RWC and membrane stability and had more negative impact on the same in ML1808. The plant growth and physiological stability of ML2056 was relatively more stable under salt stress. Melatonin reduced the some impacts of salt stress highlighted by a better chlorophyll retention, water status, membrane stability and antioxidant enzyme activity, along with less MDA and H₂O₂ accumulation. Other hallmarks of osmotic and antioxidants protection were the elevation of proline, soluble sugars, phenolics and flavonoids. Coordinated regulation of physiological, biochemical and phenolic responses was facilitated using integrated correlation analysis and PCA. To conclude, ML2056 exhibited better salt tolerance and melatonin had a positive effect on stress adaptability of mungbean.