Physiological and Metabolic Responses of Chickpea to Post-Flowering High Temperatures and Limited Water Availability

Post-flowering elevated temperatures are increasingly frequent and strongly affect crop yield and seed nutritional quality. This study examined the impact of elevated post-flowering temperatures (32°C/25°C, day/night) combined with two watering regimes (40% and 10% field capacity) on chickpea genotypes. Elvar and Electra, top-yielding Portuguese genotypes well adapted to southern Portugal's dry climate were evaluated. Under controlled high-temperature conditions (Phenolab), reproductive cycle was shortened to 30-35 days, compared with 65 days under greenhouse conditions (24°C/18°C). Water use peaked soon after flowering and declined after 19 days, regardless of genotype or watering regime, suggesting a physiological limitation on water use. Elevated temperature strongly reduced seed number and weight while altering composition. Nutrient density improved, with higher protein and mineral levels (P, Mg, S, Mo, Fe, Zn) and lower starch content, highlighting a consistent protein–starch trade-off unaffected by water availability. While growth environment largely determined composition, enzymatic activity patterns revealed genotype-specific differences in carbon metabolism (e.g. sucrose synthase, cell wall invertase, aldolase and phosphoglucose isomerase). Overall, these findings suggest genotype-specific responses driven by carbon metabolism and emphasize integrating metabolic, physiological and composition traits in breeding for yield stability and nutritional value.