Optimum Seeding Rates for Diverse Hrsw Cultivars.

Determining the proper seeding rate for specific hard red spring wheat (HRSW) cultivars as they are released is an expensive and continuous process. This research explores the relationship between planting date, cultivar, and seeding rate as they affect yield. The final expectation of this research is a predictive model to match cultivars to a proper seeding rate in the field based on expected planting date, allelic differences for Ppd1, Rht1, Rht2, and agronomic traits such as number of tillers produced and plant stature. Field experiments were conducted in 2013 at four locations and in 2014 at six locations. The experimental design at four locations was a RCBD with a split-split restriction, with the whole plot as planting date, split as HRSW cultivar, and the split-split as seeding rate. The experimental design at six locations was a RCBD with a split plot restriction, with the whole plot being HRSW cultivar and the split being seeding rate. Specific factors in the trial were two planting dates, twelve HRSW cultivars, and five seeding rates. Cultivars were chosen in pairs from the presence or absence of Ppd1, Rht1, and Rht2. Data collected was stand counts at 1-3 leaf stage, heading counts just prior to harvest, number of tillers, and yield. Results from 2014 will be presented but are yet to be harvested. Significant effects for main effects and interactions were determined for three of four locations in 2013. Cultivar yields responded differently to seeding rate as the rate increased, with some increasing, some increasing then plateauing, and some increasing to a point and then decreasing. Tillers responded as expected with increased tillers at lower seeding rates. Preliminary results show that developing strategies for seeding rates for specific cultivars based on allelic differences is possible.