Journal of Experimental Agriculture International

Correlation studies are a key tool for identifying these relationships, enabling indirect selection for yield improvement and helping breeders prioritize traits for heat resilience. The study aims to explore trait variability, their interrelationships, and contributions to yield under heat stress to support the development of high-yielding, heat-tolerant wheat genotypes. This study evaluated 50 wheat genotypes during the 2019–2020 and 2020–2021 Rabi seasons at the Zonal Agricultural Research Station, Pawarkheda, Madhya Pradesh, under three sowing environments designed to impose variable temperature regimes: early (cool conditions), normal (optimal conditions), and late (terminal heat stress). The experiment followed a randomized complete block design with three replications. The study assessed phenotypic correlations among morpho-physiological and yield traits in 50 bread wheat (Triticum aestivum L.) genotypes evaluated under Environment 1. Grain yield per plant showed strong and significant positive correlations with grains per spike (r = 0.721**), number of grains per plant (r = 0.682**), spike length (r = 0.627**), biological yield (r = 0.461**), harvest index (r = 0.745**), and spike weight (r = 0.356**), indicating that yield components and biomass partitioning are major determinants of productivity. Grains per spike also displayed significant positive associations with number of grains per plant (r = 0.697**), spike length (r = 0.572**), and flag leaf area (r = 0.489**). Tillers per plant was strongly correlated with spikes per plant (r = 0.775**), highlighting its importance in determining sink size. Physiological traits showed relevant correlations, with canopy temperature at flowering negatively associated with grain yield (r = –0.246*) and harvest index (r = –0.211*), while chlorophyll content at the vegetative stage was positively correlated with harvest index (r = 0.211*). Flag leaf area showed a significant negative correlation with chlorophyll at the vegetative stage (r = –0.291**). Overall, the correlation structure emphasizes the key role of yield components, biological yield, harvest index, and certain physiological traits in influencing grain yield, providing valuable indicators for selecting high-performing wheat genotypes.