Rising global temperatures and frequent terminal heat stress events pose a serious threat to wheat productivity, particularly in vulnerable agro-climatic zones such as North-East India. Elevated temperatures during anthesis and grain filling accelerate senescence, impair photosynthetic efficiency, destabilize cellular membranes, and reduce yield stability. Despite increasing concern, limited integrated studies have simultaneously examined physiological and biochemical determinants of heat tolerance under this regional context. The present investigation aimed to identify key physiological and antioxidant biomarkers conferring hyperthermal durability in wheat (Triticum aestivum L.).

A field experiment was conducted using a Randomized Block Design (RBD) with contrasting sowing environments (early vs. late sowing) to impose natural terminal heat stress. Physiological traits including chlorophyll fluorescence (Fv/Fm), membrane stability index (MSI), and relative water content (RWC) were measured alongside biochemical markers such as superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), malondialdehyde (MDA), and proline accumulation. Yield parameters were recorded at maturity. Data were analyzed using ANOVA to detect varietal differences, Pearson’s correlation to assess trait associations, and Principal Component Analysis (PCA) to identify major contributors to variability.