EVALUATION OF PHYSIOLOGICAL AND BIOCHEMICAL TRAITS AS SCREENING TECHNIQUE FOR HEAT STRESS TOLERANCE IN INDIAN MUSTARD [Brassica juncea (L.) CZERN & COSS.] GENOTYPES

Indian mustard is a highly valuable crop is mostly targeted for commercial cultivation. Due to intensive cropping pattern, Brassica juncea is mostly encounter with heat stress at the reproductive stage. The experiment was conducted during rabi crop season (2017-18) at Punjab Agricultural University, Ludhiana to evaluate the physiological and biochemical responses during reproductive stage in the leaves of Indian mustard genotypes. The RWC decline by 23.0%, LWR by 12.0% and MS by 36.3% while incrementing in WSD by 16.8%, RSD by 15.4% and in MI by 18.1% under delayed sowing. The upregulation of antioxidative enzymes viz. catalase by 1.51, SOD by 1.48 and POD by 1.76 fold and non-enzymatic antioxidative metabolites i.e. tocopherol by 1.82 and ascorbic acid by 2.16 by in late sowing activates the defense mechanism under heat stress. Total siliquae/plant reduced by 43.5%, seed/siliqua by 16.2% and 1000 SW by 26.5% with delayed planting. These results suggested that the physiological and biochemical responses in plants plays a significant role to reveal the underlying mechanism during stress environment. Based on plant water status, yield attributed and CSRI value of biochemical traits, genotypes HLM-41-13-2, DAR-8, CSR-45 and CSR-1163 identified as promising genotypes.