Nitrogen application rate and timing management for improved grain quality parameters of wheat crop

Abstract

Nitrogen use efficiency under flood irrigation system is generally low (30%) in field crops, which is one of the fundamental factors of high production cost in the developing countries. Optimum rate and timing of N-application is otherwise important to harvest good quality grain for backing in the recent climate change scenario. Optimum N-rate (NAR) corresponds with the application timing (NAT) has resulted in good quality grains. Aim of the study was to focus on spring wheat grain quality and N use efficiency (NUE) with NAR {i.e., 0, 100, 120, 140 and 160 kg ha-1) and NAT (i.e., 100% at sowing (NAR1), 50% at sowing and 50% at tillering (NAT2), 25% at sowing, 50% at tillering and 25% at booting (NAT3) and 25% at sowing, 25% at tillering and 50% at booting (NAT4)}. Treatment impacts were investigated focusing grain yield, grain-N, and quality parameters (i.e., crude protein, gluten, amylose and amylopectin). Experiment was a randomized complete block, in three replications, conducted at Agronomy Res. Farm of the University of Agric. Peshawar in 2016-17 and repeated in 2017-18. Results showed the highest NUE in100 kg N ha-1, followed by a decreasing rate (p<0.05) for every next N-increment. While averaged on N-rates, the highest NUE observed in NAT3 which did not differ fromNAT4 but decreased (p<0.05) for treatment NAT2 with lowest for theNAT1. Pakhtunkhuwa-2015 showed higher NUE among the varieties. Grain-N, grain yield, gluten and amylose did not differ with NAR 140 and 160 kg ha-1 as well as for the NAT3 and NAT4 but decreased for NAT2 and the lowest was noted for NAT1. The N-content of wheat grain was highest in Pakhtunkhuwa-2015, followed by Pirsabak-2015 and the lowest in DN-84. Nonetheless, grain amylopectin showed a reduction with increasing NAR and/or split N-applications from one to two and/or three doses. Cultivars did not show any changes in the amylopectin. It is concluded that in recent climate changes where flood irrigation system is practiced, three N-splits (NAT3 or NAT4) resulted higher quality grains with140 kg N ha-1 to wheat crop