Comparative analysis of drought tolerance among Indian mustard ( Brassica juncea L.) advanced breeding lines using agro‐physiological traits and yield‐based indices

Drought is a major constraint in Indian mustard production, especially under rainfed conditions. This study evaluated 11 advanced breeding lines and 3 checks under irrigated and rainfed environments during Rabi 2023–24 at BHU, Varanasi. Morphological and physiological traits, including relative water content (RWC), membrane stability index (MSI), and SPAD chlorophyll readings, were recorded. Drought tolerance was assessed using indices such as stress tolerance index (STI), geometric mean productivity (GMP), and yield stability index (YSI). Significant variation among genotypes was observed. HUJM(D)23‐01 exhibited superior drought tolerance with high seed yield, RWC, and chlorophyll content. Mean ranking and principal component analysis (PCA) confirmed its stable performance across environments. Indices like STI, GMP, and DI correlated strongly with yield under both conditions, whereas TOL and SSPI were associated with susceptibility. The study demonstrates the utility of integrating physiological traits and selection indices for identifying drought‐resilient mustard genotypes.