IMPACT OF WATER DEFICIT CONDITIONS ON MORPHOLOGICAL AND PHYSIOLOGICAL TRAITS OF SPRING WHEAT DURING EARLY AND LATE GROWTH STAGES

Background: Wheat (Triticum aestivum L.) is one of the most essential cereal crops globally due to its nutritional value and wide consumption. However, drought stress significantly reduces wheat productivity, with grain yield losses reaching up to 40% in arid and semi-arid regions. Enhancing drought tolerance in wheat is critical for sustaining food security under climate variability. Screening and identification of drought-resilient genotypes form the foundation of drought-focused breeding programs. Objective: This study aimed to evaluate the drought tolerance of fifty wheat genotypes through comprehensive physio-morphological assessments at seedling and reproductive stages under controlled and field drought conditions. Methods: The experiment was conducted at the University of Sargodha over two consecutive growing seasons (2022–2024). Fifty genotypes were first evaluated at the seedling stage under two water treatments—100% and 50% field capacity—in a factorial arrangement with three replications. Traits measured included fresh and dry shoot weight and relative water content (RWC). Based on performance, seven genotypes were selected and assessed in the field using a split-plot design with three replications under normal and drought stress. Parameters recorded included days to flowering and maturity, plant height, number of grains per plant (NOG), 1000-grain weight (GW), and grain yield per plant (GYP). Results: NR-583 recorded the highest RWC values (90.1% normal, 79.1% drought) and GYP (7.5 g normal, 6.9 g drought), followed by NR-582 (85.2%, 75.2%; 7.6 g, 6.5 g). NR-559 exhibited the most sensitivity, with the sharpest decline in RWC (65.1% to 50.1%) and GYP (7.5 g to 4.2 g). Grain weight dropped by 20–40% under drought across genotypes, while GYP decreased by up to 45%. Conclusion: NR-582 and NR-583 showed exceptional drought resilience and yield stability, making them strong candidates for future wheat breeding in water-deficit environments.