Trait-based selection for excess moisture tolerance in chickpea: genetic and physiological insights

Excess soil moisture is an increasingly important yet underexplored constraint to chickpea (Cicer arietinum L.) production. To elucidate the physiological and agronomic basis of tolerance, 191 recombinant inbred lines (RILs) were evaluated under optimum (OM), suboptimum (SM), and supra-optimum (SuM) moisture regimes. Agronomic, phenological, and physiological traits, together with Ascochyta blight severity, were assessed using variance component analysis, heritability estimates, stress indices, and multivariate approaches. Significant genotypic variation and genotype × environment interactions (P < 0.001) were detected for all traits, with high broad-sense heritability (75-91%). Excess moisture delayed flowering and maturity by approximately 16 and 12 d, respectively, and reduced seed number, biomass, and grain yield by 44-54%. However, an extended grain-filling period under SuM partially mitigated yield losses. Physiological traits, particularly normalized difference vegetation index (NDVI) at anthesis and ground cover, remained relatively stable across moisture regimes. In contrast, NDVI at podding increased under stress conditions, indicating delayed canopy senescence. These traits were strongly and positively associated with grain yield, suggesting their utility as indicators of stress adaptation and productivity. Ascochyta blight developed only under SM and SuM and was strongly negatively associated with grain yield (R² = 0.74 under SuM). Principal component analysis identified agronomic and physiological traits as the major contributors to genotypic differentiation. Consistent with these findings, stress indices identified RIL 1_97 as a superior genotype combining high yield potential with stability across moisture regimes, highlighting its value as a donor parent for breeding chickpea cultivars with improved excess-moisture tolerance. Overall, this study provides the first comprehensive field-based assessment of chickpea responses to contrasting moisture regimes and demonstrates the value of integrating physiological, agronomic, and disease-related traits for the identification of excess-moisture-tolerant germplasm and the advancement of trait-based breeding strategies.