Morpho-physiological and biochemical assessment of heat tolerance in various rice (Oryza sativa L.) genotypes
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Date
2021-02
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G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand)
Abstract
Rice is a staple food crop in global food system fulfilling the energy requirement of major part of world population. It is very sensitive to environmental factors such as temperature, light, drought etc. during critical stages of growth, such as flowering and seed development. High temperature can irreversibly damage the rice grain quality, yield and plant processes. A research
investigation was carried out to evaluate the effect of high temperature stress on morphophysiological and biochemical parameters; and to study the yield attributes of different rice genotypes under heat stressin B1 block of N. E. Borlaug crop research center, Pantnagar during kharif season 2019. Heat treatment was given to different rice genotypes during flowering by making a polythene tunnel in one block which traps heat and other block kept open as control. Both the ends were open for sufficient ventilation. Among 30 genotypes only five genotypes, viz., Vandana, IET 28417, N-22, IET 28409 and IET 27908 were selected for the further research
work on the basis of their sensitivity to high temperature and on yield attributes. Parameters such as plant height, effective tiller number, total dry matter, leaf area index, chlorophyll content, chlorophyll fluorescence, stem weight, panicle weight, number of filled
grains per panicle, number of spikelet, spikelet fertility, test weight, grain yield, harvest index, total carbohydrate and protein content of harvested seeds etc. were recorded. It was found that chlorophyll fluorescence, leaf weight, stem weight, panicle weight and TDM reduced after flowering. At maturity, there was a decrease in shoot weight, TDM, panicle weight, spikelet fertility, grain yield, harvest index andproteindue to high temperature. Physiological and biochemical analysis revealed that the carotenoid content and LAI were increased in all; whereas, carbohydrate, chlorophyll a, chlorophyll b content, test weight, spikelet number, grain number, panicle number, effective tillers and plant height were increased/decreased in some genotypes. The parameters which were positively correlated with grain yield were leaf weight, stem weight, panicle number, panicle weight, shoot weight, and TDM whereas test weight was negatively correlated. Genetic diversity was responsible for the stress effects and stress mitigation in the crop as different genotypes from diverse backgrounds showed varied results; since, out of five genotypes, IET28417 was found to be tolerant while IET 27908 and Vandana were sensitive to high temperature in the present investigation.