Effect of Heat Stress during Reproductive Stage on Plant Growth, Total Biomass Production and their Correlation with Grain Yield in Rice

Rice (Oryza sativa L.) is highly sensitive to high temperature during its reproductive stages. This study aims to elucidate the effects of heat stress during reproductive stage on plant growth, total dry matter accumulation, and their correlation with grain yield in diverse rice genotypes. A field experiment in split plot design was conducted at G.B.P.U.A.& T., Pantnagar during rainy season 2022-23, where high temperature stress was imposed on 15 rice genotypes during reproductive stage (after panicle initiation till maturity) using a polytunnel. The results showed that heat stress lead to reduction in dry matter accumulation and harvest index in 10 genotypes, although with different magnitude. The genotypes were screened into tolerant and susceptible based on yield reduction by comparing with the genotype N-22, which was used as a check for heat stress. It was observed that the genotypes, IET 29415, MTU-1282, MTU-1121, NLR-40042 and US-314 maintaining higher biomass and HI under heat stress conditions were able to maintain grain yield. The identified genotypes with better performance under heat stress conditions offer valuable genetic resources for breeding programs aimed at improving heat tolerance in rice.