Integrated Assessment of Morphophysiological and Biochemical Traits for Identifying Drought-Tolerant Bread Wheat Genotypes Under Rainfed Conditions

Water deficit is a major constraint on wheat productivity, and the reliable identification of drought-tolerant genotypes requires the integrated assessment of morphological, physiological, biochemical, and yield-related traits. Six winter bread wheat varieties and 15 advanced breeding lines grown under rainfed conditions at the Gobustan Experimental Station were comprehensively evaluated. Relative water content, soluble protein content, and the activities of aspartate aminotransferase, NADP-malic enzyme, phosphoenolpyruvate carboxylase, and NAD-malate dehydrogenase were determined. Heading time, plant height, and grain yield were also assessed. The lines Erytrospermum 100 and 21FAWWON9/Gaudio maintained relatively high flag-leaf water content and sustained metabolic enzyme activities at the later developmental stages, whereas 29th SAWYT N395 exhibited high activities of carbon-metabolism enzymes and favorable grain yield performance. Correlation analysis revealed a significant negative association between relative water content and phosphoenolpyruvate carboxylase activity, a positive relationship between NAD-malate dehydrogenase and phosphoenolpyruvate carboxylase activities, and a positive association between soluble protein content and grain yield. Overall, Erytrospermum 100, 21FAWWON9/Gaudio, and 29th SAWYT N395 were identified as promising breeding materials for improving drought adaptation and yield stability in rainfed wheat production systems.