Location, Seeding Date, and Variety Interactions on Winter Wheat Yield in Southeastern United States

In the Southeast, winter wheat (Triticum aestivum L.) is typically planted from late October to early December. However, grain yield is reduced by an interaction of weather, soil, and plant factors. From 2009 to 2012 a study was conducted at three locations in Alabama to evaluate the seeding date effect on yield and yield components of three cultivars. The AGS 2060, AGS 2035, and Baldwin cultivars were evaluated within four seeding dates at approximately 15-d intervals. Results showed that grain yield, spikes per m(2), and kernel weight declined linearly with seeding delay; however, the impact changed among years and locations within a year. The variability of kernels per spike was location specific, in the north delayed planting resulted in a greater number of kernels per spike while the opposite occurred at the central and southern locations. At most location-year combinations, seeding 2 to 4 wk later than the Extension's best seeding date resulted in yield losses; especially if warm and dry conditions were prevalent during winter and spring months at locations with sandy loam soils. Under warm and dry growing conditions, the impact of delayed planting on yield and kernel weight was the greatest for Baldwin and AGS 2035 and least for the AGS 2060. In contrast, when cold and wet growing conditions were prevalent, there were not significant planting date differences on yield and yield components. Cultivar and seeding date should be selected on a location basis due to the plant interactions with soil and weather factors.