Balancing yield and water productivity in wheat: A meta-analysis of irrigation, soil, and climate interactions

Irrigation is a critical practice for enhancing wheat productivity; however, its yield response is strongly influenced by the climate, soil properties, and management practices. Current knowledge insufficiently captures the complex interactions among these factors. To address this gap, a meta-analysis was conducted to quantify the combined effects on wheat grain yield, yield components, grain protein content, and water productivity, thereby supporting evidence-based irrigation strategies. Irrigation significantly increased the grain yield (32.47 %), spike number (19.02 %), grains per spike (12.05 %), thousand-kernel weight (3.46 %), and water productivity (2.28 %). Although irrigation affected GPC under specific conditions, there was no significant overall effect. The more modest increase in WP reflects the concurrent rise in crop water consumption (evapotranspiration) under irrigation, which partially offsets the gain from higher yield. Higher irrigation volumes, dual applications, irrigation at the jointing–flowering stage, and water-saving irrigation practices collectively enhanced yield, grain protein content, and water productivity. Irrigation volumes of 75–150 mm were identified as optimal for maximizing yield components and WP. In soils with moderate bulk density and in regions with low annual precipitation (<500 mm), irrigation combined with nitrogen application produced greater yield gains. Moreover, when mean annual precipitation was < 500 mm, wheat yield responded more strongly to irrigation, whereas water productivity increased more under 500–600 mm precipitation. The synergistic application of conventional fertilization with post-anthesis irrigation further improved wheat yield and water productivity. Overall, these findings provide an empirical basis for irrigation management in China and inform context-specific policy design across heterogeneous agroecosystems.