Chhabra, M.L.Walke, Mahadev Bapu2016-11-112016-11-112010http://krishikosh.egranth.ac.in/handle/1/85068The present investigations were undertaken to study the role of epibrassinolide (EBR) on seed germination, seedling growth, 50% seedling mortality, relative water content, membrane stability, free proline content, antioxidative enzymes and metabolites at seedling stage, while gaseous exchange and yield attributes at terminal stage in field grown Brassica juncea plants. When seedlings were grown at 25C, 30C or 35C, it was observed that 25C is optimum temperature for germination and seedling growth. The germination, speed of germination and seedling growth of Brassica juncea in general reduced when temperature was increased from 25C to 30C and 35C. Soaking seeds in EBR (10-6 M, 10-8 M or 10-10 M) for 2 hrs in general reduced germination, seedling growth and delayed seedling mortality. Higher the concentration of EBR used, more was the reduction in germination and seedling growth. Acclimation at sublethal temperature (32C) and EBR pretreatments (10-8 M and 10-10 M ) for 24 hrs prior to high temperature stress (45C) were found to be effective in imparting thermo protection at seedling stage, which is the crucial stage of plant establishment. These pretreatments helped seedling to recover from heat stress by improved relative water content, reduced per cent injury and increased free proline content. Increase in enzymatic activity of catalase, peroxidase, and also reduction in MDA, H2O2 content conferred thermotolerance. At flower cessation stage, compared to normal sown, in late sown crop the rate of photosynthesis and seed yield decreased significantly whereas, rate of transpiration and stomatal conductance increased. Rate of photosynthesis, transpiration and stomatal conductance increased in plants sprayed with EBR at flower cessation stage. Lower concentration of EBR (10-10 M) was more effective to bring consecutive improvement in gaseous exchange. EBR spray (10-10 M) increased the seed yield (13.6%) and oil content (4.23%) as compared to control. Lower concentration of EBR (10-10 M) in general was more effective in imparting thermotolerance in B. juncea.enPlanting, Sowing, Enzymes, Brassica juncea, Biological phenomena, Organic compounds, Germinability, Biological development, Yields, Developmental stagesStudies on epibrassinolide induced amelioration of high temperature stress in brassica juncea (L.) czern & cossThesis