Optimizing wheat productivity and water productivity through deficit irrigation strategies in semi-arid environments.

This study evaluated the effects of deficit irrigation strategies on wheat production, water productivity, and nitrogen dynamics in a semi-arid region of Pakistan. Field experiments were conducted over three crop seasons (2019-2022) with four irrigation treatments: 100% (I), 80% (I), 60% (I), and 40% (I) of crop evapotranspiration (ETc) requirements. Canopy cover dynamics exhibited quadratic relationships within days after sowing, attaining maximum covers of 95, 93, 89, and 75% under I, I, I, and I, respectively. Biomass accumulation followed similar quadratic trends, maximizing at 15.1 t ha, 11.0 t ha, 8.5 t ha, and 6.0 t ha for the respective treatments. Irrigation significantly affected biomass yield (BY), grain yield (GY), and nitrogen uptake, with I having higher values than deficit treatments. Relative to I, the BY decreases were 8% (I), 23% (I), and 48% (I), while the GY reductions were 7%, 23%, and 50%, respectively. Grain nitrogen uptake ranged from 123 kg N ha (I) to 59 kg N ha (I), mirroring yield trends. Water use efficiency based on biomass (WUE) and grain yield (WUE) remained consistent across I, I, and I but dropped significantly under I. The yield response factor (K) analysis indicated that wheat exhibited moderate sensitivity to water stress, with K values of 1.25 (I) and 1.02 (I). These findings suggest that deficit irrigation at 80% ETc can optimize water conservation while sustaining wheat productivity and resource-use efficiency in semi-arid environments.