International Journal of Environment and Climate Change

Terminal heat stress is a major constraint for taking a profitable wheat crop by small and marginal farmers in the Indo-Gangetic Plains of south Asia. Hence, breeders remain in constant search for heat-tolerant genotypes. The present study was conducted on 15 wheat genotypes (G1 to G15). This study was done to find out high-yielding wheat genotypes that perform stably under terminal heat stress as well as to conclude an easy phenotyping trait for this objective. The crop was grown under two environments viz., timely (17^th November, 2020) and late sown (24^th December, 2020) with three replications. The physiological traits like Normalized difference vegetation index (NDVI), canopy temperature, and above-ground biomass; and morphological (at 80, 100, and 110 DAS) and yield attributing characters viz., days to heading, days to anthesis, days to maturity, grain yield (g/m²) and Heat susceptibility index (HSI) at harvesting stage. Among the genotypes, genotype G12 (657.33 g/m²) and G14 (653.33 g/m²) performed better under the timely sown (TS) condition while genotypes G13 (486.00 g/m²) and G14 (507.33 g/m²) under the late sown (LS) condition in terms of having higher NDVI, biomass, yield, and its attributes. Heat susceptibility index (HSI) was used to assess heat tolerance. The genotype G14 was found to be highly tolerant with lower HSI under LS condition whereas G6 was highly sensitive based on highest HSI.