Trait association analysis under abiotic stresses in Indian mustard (Brassica juncea L. Czern. & Coss.): Unraveling relationships and significance

Aim: The present study was conducted to estimate the character association among yield and its associated traits and identify tolerant genotypes of Indian mustard under abiotic stress condition. Methodology: 70 genotypes and 5 check varieties of Indian mustard, viz., RH-749, NRCHB-101, RH-406, Giriraj, and Kranti were sown in augmented block design, for two consecutive seasons during Rabi 2020-21 and 2021-22, under three conditions, viz., timely sown, drought and late sown (terminal heat stress) at Agricultural Research Farm, Banaras Hindu University, Varanasi. The morphological and physiological data were observed to determine the traits associated with seed yield under abiotic stress condition. The heat susceptibility index (HSI) and drought susceptibility index (DSI) were calculated based on seed yield to categorize genotypes according to their response under stress condition. Results: Plant height, biological yield, secondary branches, number of silique on main raceme and silique per plant showed significant positive correlation with seed yield per plant under all three conditions, and the highest positive direct effect on seed yield/plant under all three conditions as per path analysis was exhibited by biological yield and harvest index. Genotypes viz., HUJM-07-06, PM-25 and Vaibhav were found to be most heat tolerant whereas Urvashi, RB-50 and BPR-543-2 were found to be most drought tolerant. Interpretation: It can be interpreted that direct selection for such traits may aid in improving seed yield per plant under stress condition and thus, be used in breeding programs to select genotypes suitable under stress environment. Key words: Drought, Indian mustard, Path coefficient analysis, Susceptible indices, Terminal heat stress