Effect of Different Nitrogen Rates and Split Applications on Growth and Productivity of Wheat Cultivars

Nitrogen (N) is an imperative nutrient for crop growth and development. Its application is associated with crop growth stages for optimum rate to overcome production cost. A field experiment was carried out for two consecutive years with the aim to investigate the integrative effects of N application rate and timing on the growth rate and yield contributing traits of wheat cultivars. The experiment was laid out in randomized complete block design with split plots arrangements using three replications for two consecutive years (2016–17 and 2017–18). The treatments combinations were N application rate (NAR; 0, 100, 120, 140, and 160 kg ha⁻¹) and timing (NAT₁: 100% of the applied dose at sowing; NAT₂: 50% at sowing and 50% at tillering (70 days after sowing; DAS); NAT₃: 25% at sowing, 50% at tillering and 25% at booting stage (100 DAS); NAT₄: 25% at sowing, 25% at tillering and 50% at booting stage). Results showed that NAR and cultivars significantly affected number of days to anthesis and plant height. The days to maturity were also significantly different regarding NAR, NAT and cultivars. Concerning crop growth rate (CGR) reported at different stages (i.e. tillering, anthesis and grain filling), an increasing trend was observed at 140 kg N ha⁻¹ and NAT₃. Similarly, 140 kg N ha⁻¹ given as NAT₃ significantly affected spike length and spike weight and resulted in higher grain yield and biomass. Hence, it can be concluded that three splits N (NAT₃) were more efficient for wheat variety of Pakhtunkhwa 2015 under the recent changes in climate, which has a shift in precipitation with more frequent distribution in the crop growth durations to overcome loss and increase wheat yield.