Ethan Cord Wyatt, Plant and Soil Sciences, Oklahoma State University, Stillwater, OK and William R. Raun, 044 N Agricultural Hall, Oklahoma State University, Stillwater, OK
In past years, grain protein concentration (GPC) has been highly variable from one location to the next. Many factors, environmental and genetic, contribute to the percent protein levels in the grain (Kramer, 1978). Along with increasing prices of inputs (land prices, machinery, fertilizer, and seed) producers continually need to adopt more efficient practices to ensure that GPC is at adequate levels so as to avoid potential dockage and/ or realize potential premiums. This study was conducted to determine the effect of droplet size and late-season nitrogen application on grain protein concentration. The effects of late season foliar N applications (post-anthesis) and droplet size on protein concentration were investigated on hard red winter wheat (Triticum aestivum L.) at three winter wheat sites in Oklahoma, Efaw (Stillwater), Lake Carl Blackwell, and Perkins. Foliar N was applied at two rates 11.2 and 22.4 kg ha-1 with three different droplet sizes per N rate; the 11.2 kg ha-1 N rate consisting of an adjuvant tank-mixed treatment and a non-adjuvant treatment. For most locations and years grain protein concentration was increased linearl with higher rates of foliar N applied. Use of the fine droplet size with a foliar N rate of 11.2 kg N ha-1 applied post anthesis with the addition of an adjuvant resulted in the highest grain protein concentration.