Winter Wheat Response to Nitrogen under Simulated Winterkill Conditions

Abstract

Winter wheat (Triticum aestivum L.) is an important crop in North America. Winterkill can reduce plant populations, subsequently causing significant yield losses. Agronomic management to mitigate yield losses associated with winterkill could be very important to wheat growers. Therefore, the objective of this study was to examine the potential of spring N fertilization to mitigate wheat winterkill‐related yield loss. Field experiments were conducted in Wisconsin during the 2007–2008 and 2009–2010 growing seasons at two locations. Five seeding rates (in million seeds ha−1) and simulated winterkill treatments (percentages, shown in parentheses) (1.85 (60%), 2.47 (45%), 3.09 (30%), 3.70 (15%), and 4.32 (0%)) and five urea N rates (0, 34, 67, 101, and 134 kg ha−1) were applied. Simulated winterkill in the form of lower spring plant populations significantly reduced wheat yield, tiller and head formation, and harvested grain quality. Nitrogen fertilization did not fully mitigate the negative effects of winterkill on yield and head population. When wheat followed oat (Avena sativa L. var. nuda), 89 and 119 kg ha−1 N maximized yield, whereas when soybean [Glycine max (L.) Merr.] preceded wheat, 43 kg ha−1 N maximized yield regardless of the winterkill level. Spring N fertilization reduced test weight by 5% in two out of three sites. The overall results suggest that additional N fertilization did not mitigate winterkill‐related impacts on wheat yield. Plant breeding focused on winter‐hardy cultivars and the potential of other agronomic factors to mitigate the impact of winterkill on wheat yield and quality should be evaluated.Core Ideas Nitrogen fertilization did not mitigate winterkill‐related impacts on wheat yield. Winterkill reduced winter wheat yield, tiller and head formation, and test weight. Considering the previous crop is important before recommending N fertilization.