Shankhdhar, S.C.Reddy, Gajji Aravinda2022-10-182022-10-182022-08https://krishikosh.egranth.ac.in/handle/1/5810189131In the global food chain, rice is a staple crop that provides the majority of the world's population with all of their energy needs. During crucial growth stages like flowering and seed development, it is extremely sensitive to environmental conditions including temperature, light, drought, etc. High temperatures have the potential to permanently harm rice grain quality, yield, and plant functions. A study was conducted at the N. E. Borlaug Crop Research Center in Pantnagar during the kharif season of 2021 to determine the effects of high temperature stress on morpho-physiological and biochemical parameters, as well as to examine the yield characteristics of various rice genotypes under heat stress. Different rice genotypes received heat treatment during blooming by creating a polythene tunnel in one block that retains heat and leaving the other block open as a control. It has openings on both ends for adequate ventilation. Only 10 genotypes—29173(R), CO-51, IET 29939, IET 29940, IET 29947, IET 29948, IET 29952, IET 29958, and IET 29960—out of 25 genotypes were chosen for further study based on their sensitivity to high temperatures and yield characteristics. Parameters regarding the physiological, biochemical and morphological characters are recorded during the investigation. It was found that stem weight during flowering, shoot weight during maturity TDM at flowering and maturity, stomatal conductance, transpiration rate, panicle dry weight during flowering and maturity, grain yield, protein, amylose and carbohydrate content was reduced during heat stress conditions. It was found that plant height at flowering, effective tiller number, LAI, leaf dry weight at flowering, photosynthetic rate, intercellular CO2 concentration, grain number and spikelet number per m2, spikelet fertility, harvest index and chlorophyll content were increase/decrease in some genotypes. When the parameters are correlated with grain yield, they are found to be positively correlated and significant except one that is shoot weight at maturity it is found to be non-significant. Different genotypes from diverse backgrounds showed varied results since, out of 10 genotypes, IET 29958 and IET 29947 was found to be tolerant while IET 29942 and 29173(R) were sensitive to high temperature in the present investigation.EnglishThesis