N Response of ‘Supersoft' White Winter Wheat in NE Oregon.

Millers and bakers prefer soft white winter wheat grain protein levels to be relatively low (<10%) and there are often premiums available for low protein grain (<8%). The Oregon State University Wheat Breeding Program has developed a ‘supersoft’ white winter wheat variety with lower grain protein and superior end-use functionality. Nitrogen fertilizer recommendations are based, in part, on yield and grain protein goals so there were questions about the most appropriate N rate to recommend that would achieve maximum yield without adversely increasing grain protein. The objectives of this research were to evaluate the effect of increasing N rates on the grain yield, protein, and N uptake of ‘Supersoft’ compared to ‘Stephens’, a standard soft white winter variety. Trials were conducted at the Pendleton (430 mm precipitation) and Sherman (280 mm precipitation) stations of the Columbia Basin Agricultural Research Center in 2005-06 and 2006-07. The trials were seeded after conventional fallow using a Hege small plot drill. Preplant N was applied as urea at rates from 0 to 168 kg N ha^-1 in 34 kg increments. Treatments were arranged in a randomized complete block design with four replications. Standard production practices were used in all trials. The plots were harvested with a Wintersteiger plot combine and grain yield and protein were measured. N uptake in the grain was calculated from the grain yield and protein values. Increasing N application rate increased grain yield, grain protein, and grain N uptake in all trials; ‘Stephens’ produced greater yields than ‘Supersoft’, higher grain protein, and more N uptake than ‘Supersoft’ in all trials.