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

  Efaw, Stillwater, OK, Perkins, OK, and Lake Carl Blackwell Randomized complete block design (RCBD), 3 reps Treatment Foliar N (kg N ha -1) 1 2 3 0 11.2

11.2

4 5 6 7 8 9 10 11.2

11.2

11.2

11.2

22.4

22.4

22.4

Droplet size — Fine, with adjuvant Medium, with adjuvant Coarse, with adjuvant Fine Medium Coarse Fine Medium Coarse Nozzle PSI MPH — — FC- TR110-015 25 GRD120-01 60 — 5 5 GRD120-015 25 FC- TR110-015 25 GRD 120-01 GRD 120-015 FC-TR110-02 GRD120-02 GRD120-02 60 25 60 60 40 5 5 5 5 4 5 5

  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

 Three to five days following application 15 flag leaves were chosen at random throughout each plot  At harvest, grain yield and subsamples of the grain were collected from each plot.

  Grain and flag leaf samples were processed and analyzed for total N using a LECO Truspec CN dry combustion analyzer Massey Ferguson 8XP combine used to harvest plots. Combine has subsampling and yield recording capabilities Grain protein % and N uptake were calculated by:  𝐺𝑟𝑎𝑖𝑛 𝑃𝑟𝑜𝑡𝑒𝑖𝑛 𝐶𝑜𝑛𝑐𝑒𝑛𝑡𝑟𝑎𝑡𝑖𝑜𝑛 % = 𝑁% × 5.7

 𝑁𝑢𝑝𝑡𝑎𝑘𝑒 (𝑘𝑔 𝑁 ℎ𝑎 −1 ) = 𝑁% 100 × 𝑌𝑖𝑒𝑙𝑑 𝑘𝑔 ℎ𝑎 −1

Trt. 5 Trt. 2 Differences visible showing awn burn from the foliar N*adjuvant treatments in 2012 Foliar N burn was more frequent in all treatments in 2013. Left, visual burn signs of foliar N application compared to the right which was the check.

Grain yield by treatment at LCB, OK, 2012.

2500 ab 2000 abc 1500 f cdef def bcde def bcd 1000 a def 500 0 Yield Relationship of grain yield and foliar N rate at Perkins, OK, 2013.

Treatment

Treatment comparisons for grain yield as influenced by droplet size and foliar N rate, LCB, OK, 2013 4400 4300 a bc d ab 4200 4100 4000 3900 3800 3700 e e e Yield 0 11.2 11.2 11.2 22.4 22.4 22.4

Check C M F C M F Foliar N Rate (kg N ha -1 ) and Droplet Size Relationship of yield and nitrogen uptake with droplet size (coarse, medium, fine) LCB, OK, 2012.

Treatment means for grain protein with mean separation at Lake Carl Blackwell, 2013. Foliar N kg ha -1 Droplet Size Adjuvant Protein % 0 11.2 11.2 11.2 11.2 11.2 11.2 22.4 22.4 22.4 None Fine Medium Coarse Fine Medium Coarse Fine Medium Coarse No Yes Yes Yes No No No No No No .05

a denotes significant differences in means, LSD .05 12.65 g 14.70 a 14.40 ab 14.30 abc 14.00 abcdef 13.44 bcdefg 13.61 abcdefg 14.25 abcd 14.14 abcde 13.20 cdefg Relationship between grain protein and foliar N rate, Efaw, OK, 2012.

Check vs foliar N, 1 vs 2-10, single degree of freedom contrast LCB, OK, 2013.

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