The rise in Earth’s temperature is one of the most alarming climatic issues in the field of agriculture and food production, in the present context. The increase in temperature leads to heat stress, major abiotic stress responsible for a huge decline in the production of crops. Wheat (Triticum aestivum), among many crops, also experiences a significant decline in yield and overall productivity due to extreme heat stress. But Wheat has also developed natural tolerance mechanisms to defend itself from heat damage. The selection of cultivars with a higher degree of tolerance mechanism protects against thermal stress, which minimizes the risk of poor productivity to a greater extent. In this review, we discuss the current works of literature concerning the heat stress tolerance mechanism in wheat plants and also highlight the strategic approaches that improve their heat stress tolerance at the molecular level. The success of these approaches depends on a better understanding of heat tolerance traits, their genomic composition, and molecular responses.

Heat stress is the major constraint for wheat production causing significant drops in the yield and potential productivity making it difficult to achieve the target yield by 2030, increasing food insecurity in Nepal. The main aim of the study is to help plant breeders to select appropriate heat stress-tolerant indices for increasing wheat yield by coping with the major problem of heat stress. The experiment holds the study for three years at the Institute of Agriculture and Animal Science (IAAS), Paklihawa campus. The experimental trial was of alpha-lattice design with 5 blocks and 4 plots. There were in total of 2 replications each of 20 genotypes. MP (Mean Productivity) had the highest strong correlation with the stress tolerance indices followed by STI (Stress Tolerance Index) for all three years, whereas YSI (Yield Stability Index) had the lowest tolerance index with a negative correlation for the years 2019 and 2021. The selection of MP and STI is encouraged for the production of heat-stress-tolerant varieties for high-yielding with tolerance.

An experimental trial of nine rice genotypes was conducted in the Agronomy field of the Institute of Agriculture and Animal Science (IAAS) Paklihawa Campus under a randomized block design layout with three replications from July to November of 2022. The aim was to study genetic variability and analyze the character association of yield and yield-attributing components in rice genotypes and their direct and indirect effect on grain yield under reproductive drought stress conditions. Observations on days to flowering (50%), plant height, panicle length, panicle weight, number of grains/panicles, effective panicle/m², grain yield, and 1000 kernel weight were recorded. Grain yield showed a highly positive significant correlation with effective panicle/m² (0.713**), followed by plant height (0.347) and panicle length (0.289). The path coefficient analysis of different traits revealed the highest positive direct effect of the effective panicle per m² (0.748963), followed by panicle length (0.24145) and plant height (0.227505). The highest negative direct effect was shown by the number of grains per panicle (-0.31218). The experimental results revealed that the selection of trait-effective panicle per square meter would be most beneficial for the improvement of yield in rice genotypes facilitating selection and plant breeding programs.