Ethan Wyatt Plant and Soil Sciences Oklahoma State University

 The United States ranks fourth in global wheat production.  In the United States more than 21 million hectares of wheat is produced each year.  Hard red winter wheat (HRWW) is grown extensively in the Great Plains region which accounts for 40% of the total wheat grown in the U.S. iwheat.org, 2013

 In recent years hard red winter wheat protein levels have been a concern with milling and baking companies.  Grain protein concentration (GPC) levels determine the degree of milling and baking quality of processed wheat products and price  As of November 30, 2010, marketable grades of HRWW must contain a protein level of at least 11% or a 10 cent dockage to the contract price with a protein level of 10.5% (KCBT, 2010)

 Grain protein levels are variable across locations due to environmental and genetic factors (Kramer, 1978)  Rao et al., (1993) GPC is controlled by many different aspects including environment, cultivar, nitrogen fertilizer rate and timing  Research on late-season top-dress N as either dry or liquid material has shown an increase in GPC (Woodward and Bly, 2003)  Woolfolk et al., (2002) GPC was increased with late season foliar N before and following flowering  According to Mercer (2007) decreasing droplet size increased uptake of the active ingredient and increased the spread area of the droplet which increased uptake of the active ingredient

 To evaluate the effects of adjuvant, droplet size, and foliar N rate on wheat grain protein and yield

TreatmentFoliar N (kg N ha -1) Droplet sizeNozzlePSIMPH 10———— 211.2Fine, with adjuvantFC- TR Medium, with adjuvantGRD Coarse, with adjuvantGRD FineFC- TR MediumGRD CoarseGRD FineFC-TR MediumGRD CoarseGRD  Efaw, Stillwater, OK, Perkins, OK, and Lake Carl Blackwell  Randomized complete block design (RCBD), 3 reps

 Foliar N applications were applied immediately following anthesis.  Alleys included in the design so foliar N application could be applied without damaging plots with the ATV applicator Experimental design and treatment layout for the Lake Carl Blackwell experiment Gary James at HYPRO Global Spray Solutions provided spray tips and technical support

Massey Ferguson 8XP combine used to harvest plots. Combine has subsampling and yield recording capabilities

Trt. 5Trt. 2 Differences visible showing awn burn from the foliar N*adjuvant treatments in 2012 Foliar N burn was more frequent in all treatments in Left, visual burn signs of foliar N application compared to the right which was the check.

Treatment comparisons for grain yield as influenced by droplet size and foliar N rate, LCB, OK, 2013 abc f ab def a bcd def bcde def cdef Grain yield by treatment at LCB, OK, Relationship of grain yield and foliar N rate at Perkins, OK, Relationship of yield and nitrogen uptake with droplet size (coarse, medium, fine) LCB, OK, 2012.

Relationship between grain protein and foliar N rate, Efaw, OK, Check vs foliar N, 1 vs 2-10, single degree of freedom contrast LCB, OK, Non-adjuvant vs adjuvant, 2,3,4 vs 5,6,7, single degree of freedom contrast, LCB, OK, 2013.

 Yield differences observed were relatively small across locations and years  For most locations and years GPC was increased linearly with higher rates of foliar N applied  When compared to the check, late season foliar N application can improve grain protein by up to 2.0%  Use of the fine droplet size with a foliar N rate of 11.2 kg N ha -1 with an addition of an adjuvant resulted in the highest GPC  This work suggests that more emphasis should be placed on protein prediction and improving mechanisms to improve late season foliar N uptake

 Late season foliar N to improve protein levels should be applied to: ◦ Growing wheat under high yielding production systems  Irrigation production systems  High rainfall areas/years ◦ Growing wheat with less than optimum nitrogen requirement applied  Late season foliar N application should be applied when: ◦ Crop is healthy ◦ Temperature is below 65 degrees F ◦ Low humidity ◦ Low wind days

 Funding, Soil Fertility Research and Education Advisory Board  Spray nozzles and droplet size technical support was provided by Gary James at HYPRO  Foliar N applicator built by Dr. Randy Taylor, BAE  Committee Members: Dr. Raun, Dr. Arnall, Dr. Taylor  PASS graduate students