The effects of variety and seeding rate on water and fertilizer requirements of winter wheat

Mastering crop water and fertilizer requirements is crucial for developing precision-based irrigation and fertilization regimes. To investigate the impacts of novel varieties and sowing rates on the water and fertilizer demand characteristics of winter wheat under sprinkler irrigation, two consecutive annual field experiments (2023–2025) were conducted in Dacaozhuang Administrative Zone, Ningjin County, Hebei Province, China. The study included a variety trial with five winter wheat varieties and a seeding rate trial with six gradients (120–518 kg ha –1 ). The measurements included reference crop evapotranspiration (ET 0 ), actual crop evapotranspiration (ET a ), crop coefficient (K c ), plant nitrogen uptake (PNU), crop water productivity (WP), and nitrogen use efficiency (NUE) across growth stages. The results indicated that annual ET 0 averaged 614.4 mm (2024) and 654.6 mm (2025), with ET a ranging from 397.6 to 430.7 mm (2024) to 382.0–416.7 mm (2025). Compared with the FAO-56 recommended K c values, the mean deviations reached –12.2% (initial stage), –7.8% (development stage), –9.8% (middle stage), and–36.2% (end stage). Both variety and seeding rate significantly influenced ET a , aboveground nitrogen uptake, yield, and WP ( P < 0.05), but had minimal effects on the stage–specific proportions of ET a , nitrogen uptake and K c values. NUE varied significantly among the seeding rates ( P < 0.05). The maximum yield (11,136 kg ha –1 ), WP (2.70 kg m –3 ), and NUE (65.7%) represented 30.8%, 45.2%, and 140.7% increases over the minimum values, respectively. Sprinkler-irrigated winter wheat management should account for varietal and seeding rate differences, adopting a nitrogen basal-topdressing ratio of 3:2; irrigation allocations of 3:4:3 at the emergence, jointing, and heading stages, and stage-specific K c values of 0.44 (initial stage), 0.85 (development stage), 1.04 (middle stage), and 0.45 (end stage). • Variety and seeding rate significantly affect ETₐ, yield, WP, and NUE of sprinkler-irrigated winter wheat. • Stable stage-specific water/nitrogen demand proportions support standardized management scheduling. • Optimized 3:2 N basal-topdressing and 3:4:3 irrigation ratios guide water-scarce winter wheat production.