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Effect of nitrogen fertilizer application rate on grain, milling and baking characteristics of soft red winter wheat
B. BAIK (1), L. Lindsey (2), E. Lentz (3) (1) USDA-ARS Soft Wheat Quality Laboratory, Wooster, OH, U.S.A.; (2) The Ohio State University, Department of Crop & Horticulture Science, Columbus, OH, U.S.A.; (3) The Ohio State University, Department of Extension, Findlay, OH, U.S.A..

The application of nitrogen (N) fertilizer to wheat crops is crucial for achieving maximum grain yield and increased protein content, especially for hard wheat. For soft wheat, on the other hand, relatively little is known about N rate effects on grain characteristics, possibly due to little interest in increased protein content. Two field experiments, one with spring applications of 0 to 160 lb/acre N fertilizer at two locations for two years and the other with 0 to 160 lb/acre in one location for three years, were conducted and the obtained grain was tested for milling and baking quality characteristics. With the increased N rate from 0 to 160 lb/acre, increases in test weight by 1.3 and 1.7 lb/bu, grain protein content by 2.1 and 2.4% and kernel hardness by 8.6 and 14.3; decreases in kernel diameter by 0.2 and 0.1 mm and kernel weight by 3.5 and 1.3 mg; insignificant changes in flour yield; and a decrease in softness equivalent by 4.0 and 5.7% were observed in the respective field experiments. Lactic acid SRC and SDS sedimentation volume of flour increased from 97.8 to 113.2 % and 91.0 to 95.9%, and from 13.2 to 23.3 mL and 11.5 to 20.3 mL, respectively, in the respective experiments with the increase in N rate from 0 to 160 lb/acre. With increases in N rate from 0 to 160 lb/acre, water SRC significantly decreased by 3.0 and 2.6 mL in the respective experiments, while little to no changes in sodium carbonate SRC of flour was observed. With the increased N rate, harder, smaller and lighter grain with increased test weight, protein content, lactic acid SRC and SDS sedimentation volume was produced. Despite increases in protein content and kernel hardness of grain resulting from the increased N rate, water and sodium carbonate SRCs of flour exhibited either decreases or no changes, which would be desirable for baking soft wheat flour products.