Identification of Heat Stress Tolerant Wheat Genotype Using Stress Tolerance Indices

Abstract

This experiment was conducted to identify heat stress tolerant wheat genotypes using stress tolerance indices. A total of twenty wheat genotypes, provided by the National Wheat Research Program (NWRP) in Bhairahawa, were evaluated in both irrigated and heat stress environments. These genotypes comprised three Bhairahawa Lines (BL), fifteen Nepal Lines (NL), and two commercial checks—Bhrikuti and Gautam. The research was conducted at the Institute of Agriculture and Animal Science (IAAS) in Paklihawa, using alpha lattice design. Results showed that the mean grain yield of wheat was reduced by 24.82% under heat stress conditions as compared to irrigated conditions. Notably, mean productivity (MP), geometric mean productivity (GMP), stress tolerance index (STI), and yield index (YI) exhibited strong and highly significant positive correlations with yield under both irrigated and heat stress conditions. In contrast, tolerance index (TOL) and stress susceptibility index (SSI) displayed negative correlations under heat stress conditions. Genotype NL 1384 exhibited the highest MP, GMP, and STI, closely followed by NL 1417, establishing them as the most stable and productive genotypes. These findings suggest that these genotypes have the potential to be selected for high yields under both irrigated and heat stress conditions. The biplot analysis showed a positive correlation of MP, STI, GMP, YI, and yield stability index (YSI) with yield in the irrigated environment (Ys) and yield in the heat stress environment (Yp), and a negative correlation of stress susceptibility index (SSI), TOL, and reduction (Red). Hence, these indices could potentially be used for the evaluation of wheat genotypes under both irrigated and heat stress conditions.