Association Analysis among Morpho-physiological Traits of Indian Mustard [Brassica juncea (L.) Czern. & Coss.] Lines under Rainfed and Irrigated Conditions

This study was conducted during rabi season (November, 2023–March, 2024) at the Agricultural Research Farm, Institute of Agricultural Sciences, BHU, Varanasi, Uttar Pradesh, India to assess the influence of key traits on seed yield in fourteen mustard genotypes grown under rainfed and irrigated conditions. Indian mustard [Brassica juncea (L.) Czern. & Coss.], a major oilseed crop, faced significant yield challenges in India due to climate change and water scarcity, which intensified biotic and abiotic stresses. Nineteen phenological, morphological, and physiological traits were analysed for correlation and path coefficients to identify those contributing most to seed yield plant-1. Under rainfed conditions, the highest positive correlations with seed yield plant-1 were observed for chlorophyll content (0.533P, 0.992G), the number of primary branches (0.600P, 0.983G), main raceme length (0.540P, 0.943G), number of siliquae plant-1 (0.669P. 0.902G), plant height (0.615P, 0.883G), number of siliquae on main raceme (0.523P, 0.720G), and test weight (0.554P, 0.920G). In irrigated conditions, traits like number of secondary branches (0.609P, 0.699G), main raceme length (0.422P, 0.936G), chlorophyll content (0.583P, 0.760G), yield ha-1 (0.617P, 0.717G), siliquae plant-1 (0.580P, 0.655G), and plant height (0.470P, 0.543G) showed strong correlations with seed yield. Path analysis revealed biological yield and harvest index exhibited the highest positive direct effects on seed yield in both conditions highlighting their importance for direct selection. Therefore, these characters should be considered to improve the seed yield plant-1 in rainfed and irrigated conditions.