Identification of drought-tolerant and stable mung bean genotypes using stress tolerance indices

Mung bean (Vigna radiata L. Wilczek) is an important grain legume increasingly cultivated in water-limited environments. However, strong genotype × environment interaction (GEI) often complicates the identification of broadly adapted and drought-tolerant genotypes. This study integrated multi-environment phenotypic evaluation with molecular characterization to identify superior mung bean genotypes for stressful environments.

Nine mung bean genotypes were evaluated under two irrigation regimes across two growing seasons. Environmental effects accounted for more than half of the total variation in seed and biological yields, while drought stress reduced seed yield by 25.66% across genotypes. Green seed fresh weight per pod, green pod fresh weight, and thousand-seed weight exhibited high broad-sense heritability coupled with high genetic advance, indicating favorable prospects for selection. Stress tolerance index (STI), geometric mean productivity (GMP), and mean productivity (MP) were strongly associated with grain yield under drought conditions. Multi-environment analyses revealed significant GEI, with the first two AMMI interaction principal components explaining 95.04% of the interaction variance. GGE biplot and complementary stability statistics consistently identified G8 as the highest-yielding genotype and G6 as the most stable across environments, whereas G8, G3, and G6 combined superior productivity with favorable yield stability. SCoT marker analysis generated 44 amplification products, of which 42 were polymorphic (95.45%), confirming substantial genetic diversity among the evaluated genotypes. The molecular analysis further supported the phenotypic differentiation of the superior genotypes, particularly the mutant-derived genotype G6, thereby strengthening confidence in its selection as a valuable breeding resource.

The integration of drought tolerance indices, multi-environment stability analyses, and SCoT molecular markers provided a framework for identifying superior mung bean genotypes under contrasting irrigation conditions. G8 was identified as the most productive genotype, whereas G6 combined broad adaptation with high yield stability and detectable molecular differentiation from its parental genotype (G1). These findings provide valuable genetic resources for developing climate-resilient mung bean cultivars and demonstrate the advantage of combining phenotypic and molecular approaches to improve breeding decisions under water-limited environments.