Assessment of terminal heat tolerance ability of wheat genotypes based on chemometric analysis and agro-physiological traits

Climate change causes a substantial impact on wheat yield and heat stress at the end of the harvest is a major problem for wheat production in India. Therefore, a study was carried out to ascertain the effects of terminal heat stress on 40 genotypes of Indian wheat with respect to 7 physiological and 6 agronomic parameters. Using chemometric analysis, such as principal component analysis (PCA), agglomerative hierarchical cluster analysis (AHC), and heat maps, the genotypes were grouped. Based on AHC and heat maps, the genotypes were divided into three clusters: tolerant, moderate, and sensitive. Tolerant genotypes such as DBW14, RAJ 3765, WH730, NW1014, and HALNA exhibited improved physiological response in terms of membrane stability index (MSI), chlorophyll content (CHL), photosynthesis rate (PN), antioxidative performance, and yield attributes under heat stress conditions while genotypes like Chirya7, HW2004, and many others were found to be relatively heat sensitive. Physiological traits like MSI, CHL, Proline, catalase (CAT), and PN were found to be the main determinants of genotype group assignments and showed positive correlations with grain yield. The results indicated that Thousand-grain weight (TGW), Grain yield (GY), and MSI could be used for the identification and assortment of heat-tolerant genotypes. In conclusion,thousand-grain weight (TGW) can be employed as a final assessment of heat tolerance after harvest. The findings also suggest that tolerant genotypes such as DBW 14, RAJ 3765, WH730, NW1014 HALNA, HI1563, and WH730 can be employed to develop climate-resilient varieties for India or other countries experiencing high-temperature stresses (HTS) at their terminal stage.