Impact of nitrogen fertility on the production performance of four hard red spring wheat cultivars

Under rainfed conditions, apart from genetic differences, N fertility is a major determinant of grain yield and grain N concentration of hard red spring wheat (Triticum aestivum L., HRSW). ­The goal of this study was to determine if prescriptive N recommendations are needed or useful for individual HRSW cultivars to maximize their grain yield and grain N concentration. To answer this question, the impact of N fertility was determined on the production performance of four HRSW cultivars. Field experiments were conducted from 2010 to 2012 with Faller, Samson, Glenn, and Vantage cultivars known to vary in their potential to produce grain yield and grain N concentration at low, medium, and high N fertility levels. Averaged across treatments, grain yield in 2010, 2011, and 2012 was 5.4, 4.6, and 4.2 Mg ha^–1. Differences in grain yields were observed only in 2011; Faller produced greater grain yield (5.2 Mg ha^–1) than Glenn (4.4 Mg ha^–1) and Vantage (4.5 Mg ha^–1). In 2010 and 2012, Glenn and Vantage produced around 7 to 10% greater grain N concentration than Faller or Samson. Increasing N fertility from low to medium generally increased grain yield, total dry biomass, grain N concentration, grain N removal, as well as decreased nitrogen harvest index (NHI) and various N efficiencies; but no significant differences were observed when N fertility increased from medium to high. Nonsignificant N fertility and cultivar interaction for each measured parameter suggests that the varying N fertility had little effect on the genetic ability of the cultivars’ production performance.