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% (I100), 80% (I80), 60% (I60), and 40% (I40) 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 I100, I80, I60, and I40, respectively. Biomass accumulation followed similar quadratic trends, maximizing at 15.1 t ha-1, 11.0 t ha-1, 8.5 t ha-1, and 6.0 t ha-1 for the respective treatments. Irrigation significantly affected biomass yield (BY), grain yield (GY), and nitrogen uptake, with I100 having higher values than deficit treatments. Relative to I100, the BY decreases were 8% (I80), 23% (I60), and 48% (I40), while the GY reductions were 7%, 23%, and 50%, respectively. Grain nitrogen uptake ranged from 123 kg N ha-1 (I100) to 59 kg N ha-1 (I40), mirroring yield trends. Water use efficiency based on biomass (WUEb) and grain yield (WUEg) remained consistent across I100, I80, and I60 but dropped significantly under I40. The yield response factor (Ky) analysis indicated that wheat exhibited moderate sensitivity to water stress, with Ky values of 1.25 (I60) and 1.02 (I80). 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.