Indexing heat stress-induced changes in Indian mustard germplasm using biochemical traits, stress tolerance indices and seed morphological features

Heat stress in Brassica is a great threat to its productivity and it is a major abiotic challenge in the current scenario of changing global climatic conditions. Oil production from Brassica is the second largest production after soybean, globally. In this study, 32 Indian mustard accessions were evaluated (post-anthesis stage) under heat stress in field conditions during the rabi season of 2019-20, by being exposed to 3 different growing conditions i.e., early, optimum and late sowing. Biochemical assays were performed at the post-anthesis stage to analyze the best-performing accessions under heat stress during the rabi season of 2021-22. Seed morphological parameters and stress indices (MDA, proline content) were used to find high-performing accessions. The results showed a significant correlation between yield under stress and STI (stress tolerance index), YI (yield index), SSPI (stress susceptibility percent index) and MP (mean productivity), indicating the utility of these indices in the selection of heat-tolerant and high-yielding lines. Based on the morphological, seed yield and quality parameters, accessions IC280920, IC401575, IC426400, IC491509 and IC570301 were found tolerant to heat stress as compared to other accessions. Therefore, the selected accessions can be utilized to improve crop Brassica, especially under heat stress.