Scilight Press

The production and productivity of wheat are mainly limited by terminal heat stress in the South Asian regions of the world. The limited production of wheat has posed a significant threat to the food and nutritional security of the world. A field experiment was conducted to evaluate the heat stress tolerance of 20 elite wheat lines comprising 15 Nepal lines, two Bhairahawa lines, and three commercial checks viz., Bhrikuti, Gautam and RR 21. The field experiment was carried out using alpha lattice design at the Institute of Agriculture and Animal Science (IAAS), Paklihawa campus, Bhairahawa under irrigated and heat stress conditions. Heat stress environment was created by sowing the genotypes one month later as compared to irrigated and the evaluation was done using seven stress tolerance indices. The mean grain yield of wheat was reduced by 45.29% under heat stress conditions as compared to irrigated conditions. The correlation revealed the grain yield under irrigated condition (Yp) had a highly significant positive association with TOL (0.657), MP (0.916), GMP (0.917) and STI (0.836) and the grain yield under heat stress condition (Ys) had a highly significant positive correlation with YSI (0.694), MP (0.855), GMP (0.853) and STI (0.927; P<0.01). The grain yield under both the conditions (Yp and Ys) had a significant positive association with MP, GMP, and STI, so these indices can be used for the evaluation of highyielding heat-stress tolerant genotypes. The principal component analysis revealed NL1402, NL1488 and NL1447 as the heat-tolerant genotypes that can be recommended in the tropical region of Nepal to increase the overall production and productivity of wheat.