Seeding Rate, Genotype, and Topdressed Nitrogen Effects on Yield and Agronomic Characteristics of Winter Wheat

Winter wheat (Triticum aestivum L.) yield produced in Nebraska is often inconsistent, mainly due to environmental variability. Managing production practices could partially mitigate this problem. The objective of this study was to determine the effects of seeding rate (0.5, 1, and 2 times of the normal seeding rate), genotype (6), and topdressed nitrogen (0 and 34 kg N ha(-1) at the flag leaf stage) on the yield and agronomic characteristics of winter wheat. Experiments were conducted under rainfed conditions at the Agronomy Research Farm (ARF; Lincoln, NE) and the High Plains Agricultural Laboratory (HPAL; Sidney, NE) in 2014 and 2015. A randomized complete block design with a split factorial arrangement of four replicates was used. Nitrogen was applied to the whole plots and factorial combinations of the six genotypes and three seeding rates were applied to the split plots. Normal seeding rates were 186 seeds m(-2) at HPAL and 252 seeds m-2 at ARF. Nitrogen fertilization significantly increased yield and net returns (US$101 at ARF to $96 at HPAL) in 2014. Grain yield increased in response to seeding rate for both sites and years. Twice, the seeding rate increased grain yield, by 5% in 2014 and 13% in 2015 at ARF. The corresponding yield increase was 9% in 2014 and 5% in 2015 at the HPAL site. Estimated net return was $17 and $21 ha(-1) at ARF, and $10 and $81 ha(-1) at HPAL in 2014 and 2015, respectively.