Author(s):

D Panda, M Biswal, L Behera, MJ Baig, P Dey, L Nayak, S Sharma, S Samantaray, U Ngangkham and A Kumar

Abstract: Low light resulting from overcast skies during wet season is one of the important constraints in achieving high crop productivity. Field experiments were conducted to investigate the effect of low light stress on photosynthesis, chlorophyll accumulation, grain yield and yield components of rice. Five rice genotypes, Nirajo, Purnendu, Malliksalli, Megha Rice-1 and ASD-14 along with tolerant check, Swarnaprabha and susceptible check, IR-8 were grown under 100% and 75% of full sunlight intensity. Plants exposed to depleted radiation during reproductive stage were found to accumulate more of total chlorophyll but reduced Chl a/b ratio in the flag leaf and lesser net photosynthetic rate, stomatal conductance and rate of transpiration, which contributed to reduction in grain yield in all the genotypes Purnendu and Nirajo exhibited highest reduction in Chl a/b ratio and lesser reduction in starch accumulation in grains compared to others. Though there was significant reduction in grain yield of all genotypes, Purnendu and Nirajo exhibited relatively less grain yield loss which suggests there genetic competence to adapt to low light stress by retaining a reduced Chl a/b ratio and permitting insignificant curtailment in photosynthetic rate during reproductive stage under the subjected stress condition. Thus, they can be recommended for cultivation in regions prone to low light stress.

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