Genetic variability, heritability, and multivariate analysis of drought tolerance-related traits in field pea (Pisum sativum L.) under varying drought stresses
Field peas (Pisum sativum L.) withstand short-term drought stress; however, prolonged water deficiency causes a significant reduction in grain yield, reported up to 25%. Drought tolerance is a complex mechanism involving the morphological, physiological, molecular, and cellular mechanisms. This study aimed to quantify genetic variability and identify key physiological traits governing drought tolerance in field pea under contrasting water stresses. Thirty-six pea genotypes were utilized to determine the inheritance of drought tolerance using a completely randomized design (CRD). Key traits evaluated include plant height, leaf area, days to fifty percent flowering, root length, shoot to root ratio, chlorophyll content, electrolyte leakage, relative water content, and proline accumulation. Highly significant differences (P ≤ 0.01) were observed for all traits, indicating substantial genetic variability. Plant height, root length, relative water content, and chlorophyll content exhibited high GCV, heritability, and genetic advance, indicating strong additive gene action and suitability for selection. Under drought stress, physiological traits including relative water content, leaf area, and chlorophyll content remained key contributors to variability, as confirmed by principal component analysis. Findings revealed a strong positive correlation among root length, leaf area, and relative water content, highlighting their collective role in drought tolerance. In contrast, yield per plant showed weak and inconsistent correlations under stress, suggesting its complex inheritance and dependence on multiple interacting traits. This weak association of yield with individual traits under severe stress suggests that indirect selection through key physiological traits may be more effective for improving productivity under drought conditions. Traits such as root length, relative water content, and chlorophyll content can be effectively used for selecting drought-tolerant genotypes.