Tolerance indices based evaluation of wheat (Triticum aestivum) genotypes under terminal heat stress conditions

Abstract

Present study was carried out during winter (rabi) seasons of 2021–22 and 2022–23 at Crop Research Centre, Sardar Vallabhbhai Patel University of Agriculture and Technology, Meerut, Uttar Pradesh to evaluate the terminal heat tolerance ability of 30 wheat (Triticum aestivum L.) genotypes using 8 heat stress tolerance indices. The results indicate that 12 genotypes showed low yield reduction as compared to average yield reduction. The stress susceptibility index (SSI) was observed as robust indicator for identifying heat-tolerant genotypes. Stress tolerance index (TOL) was observed crucial which reflects genotype's ability to maintain grain yield under terminal heat stress. Analysis of correlation revealed positive relationships between grain yield under normal and stress conditions, suggesting that best-performing genotypes under normal conditions also perform well under terminal heat stress conditions. Principal component analysis and biplot analysis further confirmed the importance of studied tolerance indices for identification of heat tolerance genotypes. PC1 was associated with yield potential and heat tolerance, while PC2 was associated with stress susceptibility. Based on analysis, genotypes, viz. DBW14, DBW90, HD2864, HD2932, HD2985, HS375, HUW234, RAJ4083, WH1021, WH1124, DBW71 and PBW757 exhibited higher terminal heat stress tolerance. Cluster analysis revealed two major clusters, cluster I contained 12 heat tolerant genotype while cluster II was consisting 18 heat susceptible genotypes. The SSI and TOL index were found promising indices for identification of heat tolerant genotypes of wheat.

Keywords

• Cluster analysis, Susceptible, Tolerant, Terminal heat stress, Tolerance indices, Wheat