Exploring Varietal Response of Soft White Winter Wheat to Nitrogen and Seeding Rates in Northern Idaho.

The Mediterranean-type climate and rich soils of northern Idaho are ideal for production of high yielding soft winter wheat. New cultivars are continually developed that have improved disease resistance, agronomic performance or yield potential.  In addition to regionally adapted varieties being developed by Universities in the Pacific Northwest, a number of new varieties with European background were introduced to the area through private companies.  There is interest in exploring whether some of the European germplasm and newer regionally adapted varieties will differ from older varieties in how they respond to nitrogen fertilizer and seeding rates. In the fall of 2014, ten cultivars were evaluated at two locations (Genesee and Reubens, ID) using several nitrogen and seeding rates. These included Brundage 96, UI-WSU Huffman, UI Magic CLP, IDN01-10704A, IDN02-29001A, SY-Ovation, LCS Artdeco, LCS Biancor, LCS Drive, and LWW10-1073. The nitrogen fertilizer rates included 1.5, 2.0, 2.5 and 3.0 lb nitrogen for each bushel of expected yield per acre and the seeding rates tested were 0.6, 0.8 and 1 million seeds per acre. The average yield at Genesee was higher (110 bu/ac) than at Reubens (76 bu/ac), and both were near the anticipated yield goal for each location. While seed rates had no impact, as the nitrogen fertilizer rates increased, there was a corresponding increase in yield: 96 to 120 bu/ac for Genesee and 63 to 84 bu/ac for Reubens.  As expected, the grain protein increased while the test weights decreased with increasing nitrogen rates. Variability in variety response to increasing nitrogen rates was observed with some varieties responding favorably to increasing rates while others do not.  While increasing yields may be observed with higher than recommended nitrogen rates, increases in grain protein and reduced test weights may influence the value of the harvested grain, offsetting gains in yield.