1. Effects of Late Nitrogen Application on Hard Spring Wheats Russ Karow 1, Ernie Marx 1, Doug Engle 2, Gary Hareland 3 and Jennifer Kling 1 1 Oregon State University 2 USDA-ARS Washington State University 3 USDA-ARS North Dakota State University

2. . Background  Wheat growers in the Pacific Northwest sometimes apply nitrogen at flowering to increase grain protein in an attempt to assure meeting minimum market protein levels  Premiums are based on the assumption that higher protein equals improved end-use quality  Some reports suggest that the increase in protein percent that may occur with late N applications is not always accompanied by a corresponding increase in baking performance

3. Possible explanation for lack of improvement in baking quality with increased protein content  Late N application may increase nonprotein N or protein fractions that do not confer improved baking quality

4. Objectives  Compare the effects of single vs. split nitrogen applications on wheat yield, protein, and loaf volume  Determine if there are varietal differences in response to split nitrogen applications

5. Methods Location Hyslop Field Station, Corvallis, Oregon - 1998 and 1999 Varieties ‘WPB936’ – hard red spring wheat ‘Winsome’ – hard white spring

6. Methods Agronomic practices 30 PLS/ sq ft – earliest possible spring seeding Harmony Extra and phenoxy at 3-lf Fungicide as needed for leaf rust control

7. Methods Nitrogen treatments Early N = single application at late-tillering Split N = first application at late-tillering with 40 lbs N/acre applied as a foliar acid- neutralized urea solution at flowering Total N applied was the same for both Early and Split N treatments (40, 120, 160, 200, 240 lbs N/acre)

8. Nitrogen application

9. Preboot

10. Near harvest

11. Methods Baking quality Standard pup loafs at WWQL Experimental Design RCBD with four replications for grain yield and protein and two replications for loaf volume

12. Analysis of Variance 1998

13. Regression of grain yield on total N applied 1998 WPB936 y = 66.15 + 0.0373x Winsome y = 71.444 + 0.041x 50 60 70 80 90 100 110 120 160200240 Total N applied (lbs/acre) Yield (bu/acre) Regression of 1000 kernel weight on total N applied 1998 20 25 30 35 40 45 50 120160200240 Total N applied (lbs/acre) 1000 kw (g) WPB936 Winsome

14. Regression of loaf volume on total N applied 1998 WPB936 y = 444.25 + 4.541x - 0.009x 2 Winsome y =20.00 + 7.297x - 0.016x 2 600 650 700 750 800 850 900 950 1000 1050 1100 120160200240 Total N applied (lbs/acre) Loaf volume (cc) Regression of protein % on total N applied 1998 WPB936 y =7.0974 + 0.0455x - 8E-05x 2 Winsome y = 6.264 + 0.0435x - 9E-05x 2 9 10 11 12 13 14 15 120160200240 Total N applied Grain protein %

15. Analysis of Variance 1999

16. Winsome 1999 50 60 70 80 90 100 110 120 04080120160200240280 Total N applied (lbs/acre) Yield (bu/acre) ** + WPB936 1999 50 60 70 80 90 100 110 120 04080120160200240280 Total N applied (lbs/acre) Yield (bu/acre) All N applied at late tillering Split N application ** * All N applied at late tillering Split N application

17. 35 40 45 50 55 60 04080120160200240280 Total N applied (lbs/acre) 1000 kw (g) * * ** 35 40 45 50 55 60 04080120160200240280 Total N applied (lbs/acre) 1000 kw (g) + ** + Winsome 1999 WPB936 1999 All N applied at late tillering Split N application All N applied at late tillering Split N application

18. WPB936 1999 9 10 11 12 13 14 15 04080120160200240280 Total N applied (lbs/acre) Protein % ** * All N applied at late tillering Split N application Protein % 9 10 11 12 13 14 15 04080120160200240280 Total N applied (lbs/acre) ** * * * Winsome 1999 All N applied at late tillering Split N application +

19. Loaf volume (cc) 600 650 700 750 800 850 900 950 1000 1050 04080120160200240280 Total N applied (lbs/acre) All N applied at late tillering Split N application 600 650 700 750 800 850 900 950 1000 1050 04080120160200240280 Total N applied (lbs/acre) Loaf volume (cc) All N applied at late tillering Split N application Winsome 1999 WPB936 1999

20. . Conclusions  Yield, protein content, and baking quality increased with total N applied in both years.  In 1999, a split application of N reduced yields at lower N levels, but had no effect on yield at higher N levels.  A split application of nitrogen increased protein content in a favorable year (1999), but not in 1998 when the crop experienced other environmental stresses.  A split application of N did not significantly increase loaf volume in either year.

21. . Conclusions  The variety WPB936 was higher in protein content and had better baking quality than Winsome, but was lower yielding under all fertility regimes in both years. WPB936 had higher 1000 kernel weight than Winsome.  Further studies are underway to investigate the effects of late N application on protein composition, to determine why there is no improvement in baking quality with increased protein content.