Impact of Low Light Stress on Physiological Characters, Yield and Yield Attributes of Rice (Oryza sativa L.)

Background: Keeping in view of low light effect on rice yield and quality, identification of low light tolerant genotypes as donor for plant breeding program is needed. Methods: Field experiments were conducted for low light tolerance during kharif 2021 at Regional Agricultural Research Station, Maruteru with an aim to screen and identify low light tolerant cultivars. The impact of low light was investigated on physiological, yield and yield attributes of eighteen rice genotypes. Result: Low light treatment resulted and increase in mean days to 50% flowering and days to maturity. An increment of both plant height and leaf area was noted under low light stress in all the tested genotypes. Yield and yield attributes such as panicle number, grain number per panicle and test weight were also affected. The reduction in total dry matter and harvest index was recorded on exposure to low light condition. Under low light grain yield was maximum in IET 29032 followed by IET 30408 and Gayatri and these were identified as low light tolerant genotypes. These genotypes had a higher panicle number. Genotype Gayatri showed maximum 1000 grain weight and minimum reduction in harvest index was evident in IET 29032 and IET 30408. The chlorophyll a pigment content reduced under low light while majority of the genotypes showed an increase in chlorophyll b pigment. Gayatri followed by IET 29032 and IET 30408 retained higher chlorophyll content under low light stress. Lesser reduction in chlorophyll content (less than 13%) was evident in IET 30408, Gayatri, Swarnaprabha, IET 29031 and IET 29032.