Vol. 11, Issue 11 (2022)

Crop productivity is seriously threatened by heat stress, which is caused by high ambient temperatures, on a global scale. Particularly CO₂, methane, chlorofluorocarbons, and nitrous oxides are greenhouse gases emitted as a result of human activities in agriculture. Presently, rice is cultivated in areas where temperatures are already close to their optimum levels; hence, a further rise in global temperature at vulnerable periods may be supra-optimal and may decrease grain production. The impact of heat stress on the morphology and growth of rice must be understood in light of the aforementioned facts. Therefore, the following objectives were established for this study, i.e., to analyze the effects of heat stress on rice growth and morphology, and to assess the response of various rice cultivars for growth and grain yield across growing environments. Normal growing (25 °C±2) and heat stress (42 °C±2 daytime and 25 °C±2 night time) experiment was set up. Stress has been imposed for 6 continuous days during the panicle initiation stage for ten rice cultivars (IG-333, IG-235, IG-354, IG-170, ARB-6-11, Nagina-22, MTU-1010, Swarna, Dagaddeshi, and R-RF-127). Using a measuring scale, the Flag leaf's length, flag leaf width, panicle length, plant height, and panicle exertion were determined. Five primary tillers randomly chosen were taken & counted. Plant height, number of tillers, panicle length, & 50% flowering are found high in control when compared with stress conditions. Flag leaf length, flag leaf width, flag leaf area, and panicle exertion were increased in stressed genotypes. On the basis of morphology and yield, IG-333 and R-RF-127 (table 1 and table 2) are found to show heat stress tolerance when compared with check. No major change in plant height was recorded in heat stress and control, especially in Nagina-22. MTU-1010 genotype was found to be susceptible on the basis of yield and morphological analysis. A highly significant and positive correlation was found between flag leaf length and flag leaf area, and flag leaf width and flag leaf area in both control and heat stress conditions. A significant and positive correlation was observed between the number of tillers and days to 50% flowering under control and heat stress conditions.