Influence of Droplet Size of Foliar‐Applied Nitrogen on Grain Protein Content of Hard Red Winter Wheat

Abstract

Core Ideas Application of foliar‐applied N postanthesis increased grain protein concentration (GPC). Increasing GPC of wheat may allow producers to avoid costly discounts and obtain premiums. No differences were observed in performance among three common agronomic droplet sizes. Improvement in GPC is related to the amount of N measured in the flag leaf after foliar N application. Larger increases in GPC are observed when grain yields are at or above average. Effectively increasing the grain protein concentration (GPC) of hard red winter (HRW) wheat (Triticum aestivum L.) would allow producers to obtain adequate GPC levels while avoiding costly discounts and potentially obtaining protein premiums. The objective of this trial was to evaluate the effects of different droplet sizes and N rates applied postanthesis to winter wheat grain yield, GPC, and flag‐leaf N concentrations. Foliar applications of N were made postanthesis at rates of 10 and 20 lb N/acre. Each N rate was applied at three different droplet sizes: fine, medium, coarse. The application of foliar N postanthesis did not greatly influence grain yield, but it typically increased the final GPC. The improvement in GPC was significantly related to the amount of N measured in the flag leaf after the foliar N application. Larger increases in GPC were observed when grain yields were at or above the average for the region. No consistent effect of droplet size on GPC and flag‐leaf N was observed. In conclusion, applying foliar N fertilizer postanthesis potentially allows producers to effectively manage and manipulate their final GPC of HRW wheat.