Drought Tolerance in Lentil: Multi‐Season Phenotyping and Trait Validation Across the Stages

ABSTRACT Drought stress is a primary abiotic constraint limiting lentil ( Lens culinaris Medik.) productivity globally, and identifying genotypes with stable physiological tolerance across multiple growth stages is essential for developing climate‐resilient varieties. This study combined multi‐season field screening of diverse lentil germplasm panel using seedling vigour derived stress susceptibility index (SSI), a measure of proportional reduction in seedling vigour under stress relative to control adjusted by overall stress intensity followed by physiological and biochemical validation of contrasting genotypes under drought stress at seedling and reproductive stages. Multi‐season screening identified 11 tolerant genotypes (IC560051, IC560246, IC560032, IG134349, IC201678, P3227, IC559924,. IC559666, IG130033 and P3208 including check FLIP‐96‐51) with lower mean SSI rank values. Seedling vigour‐derived SSI provided a proxy for selection of stress‐tolerant genotypes at an early growth stage. Contrasting genotypes tolerant IC560246 and highly sensitive IC424523 along with their checks FLIP‐96‐51 (tolerant) and JL3 (sensitive) were evaluated for physiological traits (NDVI, canopy temperature), antioxidant enzyme activities (SOD, CAT, POX), lipid peroxidation (TBARS), root system architecture (RSA), biomass, and yield components. Tolerant genotypes maintained superior trait values under drought, with markedly smaller reductions in NDVI, biomass, and root architecture, along with elevated antioxidant enzyme activities and lower lipid peroxidation compared to sensitive genotypes. Principal component analysis indicated that antioxidant enzymes (SOD, CAT, POX) and growth traits were the key contributors to drought‐stress‐related variance at both stages. Correlation analysis identified traits strongly associated with seed yield ( r > 0.80), including shoot and root fresh weight, number of branches, and antioxidant enzyme activities that were correlated to seed yield, while shoot dry weight, total root length, surface area, NDVI, and number of pods had strong correlations at the reproductive stage only. These traits were subsequently integrated into a multi‐trait composite drought tolerance index. A promising tolerant genotype, IC560246 was identified with validated tolerance stability across growth stages, offering potential as a donor for developing climate‐resilient lentil varieties.