Shankhdhar, S.C.Bhatt, Priyanka2021-10-282021-10-282021-09https://krishikosh.egranth.ac.in/handle/1/5810177450Rice (Oryza sativa L.) is the world single most important food crop, being the primary source for more than one third of the world population. Rice is not only the most widely used food crop by a third of the population of the world, but it has also been established as the model monocot plant for study. Rice is extremely sensitive to the environmental factors as, solar radiation, temperature, rainfall, relative humidity and wind. Light is one the most important factor that determines plant growth and development. In some areas of the world with continuously cloudy weather or rainfall, rice yields can be reduced by 30% to 50% indicating that low light is an indispensable problem for rice production. For the Morpho - physiological, biochemical and agronomic responses of rice (Oryza sativa L.) under low light stress condition, a field experiment was conducted in A2 block of Norman E. Borlaug crop research center, G.B. Pant University of Agriculture and Technology, Pantnagar during Kharif season 2020 with twenty one rice genotypes namely, IET 27537, IET 27547, IET 28264, IET 28276, IET 28281, IET 28283, IET 28286, IET 26692, Pooja, IET 26744, Swarnaprabha, IET 29025, IET 29026, IET 29027, Gayatri, IR-8, IET 29029, IET 29030, IET 29031, IET 29032, IET 29033. Swarnaprabha was taken as a check variety among all the parameters. All twenty one genotypes were transplanted in two blocks control i.e., normal light and treatment i.e., which was imposed with low light stress by covering the blocks with 50% shade net supported by bamboo sticks and both the entry ends were left open for proper ventilation. Among the twenty one genotypes only five genotypes attained maturity specifically, IET 28281, IET 29025, IET 29027, Gayatri, and Swarnaprabha. Several parameters namely, plant height, tiller number, leaf area index, leaf dry weight, stem dry weight, total dry matter, panicle number, panicle weight, spikelet number, filled grains, thousand grain weight, grain yield, harvest index, chlorophyll content, carbohydrate content and malondialdehyde content were recorded for the rice genotypes and it was recorded that except plant height, leaf area index, chlorophyll content all the parameters significantly reduced under low light stressed conditions. Due to some genotypic variations some genotypes were regarded as the tolerant genotypes and some as the susceptible genotypes. The low light tolerant genotypes performed better in terms of grain yield, harvest index in comparison to less tolerant and susceptible genotypes. In the present study, genotype IET 28281 was found highly tolerant to low light stress followed by moderately tolerant genotype IET 29027 and the genotype IET 29025 was found least tolerant to low light stress. A positive correlation of most of the morpho-biochemical and yield parameters with grain yield at control (normal) light conditions and a negative correlation of these parameters were found at low light conditions.EnglishThesis