Effects of Planting Date and Variety Selection on Winter Wheat Yield in Alabama.

Understanding the factors impacting wheat yield might lead to the identification of opportunities to increase yield potential. The objective of this study was to assess the effect of planting date and variety maturity on winter wheat production in Alabama. The study was conducted during 2009-2010 and 2010-2011 growing seasons at three research stations across Alabama: Tennessee Valley (TVS), Wiregrass (WGS), and E. V. Smith (EVS). Wheat was planted in a split plot design with five replications. Four planting dates at approximately 15 day intervals were assigned as main plots, and three varieties with early (AGS 2060), medium (AGS 2035), and late maturity (Baldwin) were randomized within the subplots. Results from this study showed yield differences associated with location by planting date by maturity group interaction. Regardless of location and year, yield decreased as planting was delayed for the medium and late maturing cultivars. Data showed that weight per seed, and yield could be increased if specific cultivars were planted 15 days earlier than typical planting date used by farmers at each location. The medium and late maturities had the greatest yield at all locations for the early planting dates. At EVS, the early maturing cultivar’s weight per seed, number of seeds per hectare, and yield increased when planted at the second planting date and decreased when postponed. At the fourth planting date, the early maturity out yielded the medium and late. Canonical discriminant analysis was also performed to describe yield variation in terms of yield components and to identify the planting date and variety on yield variation. Canonical discriminant analyses revealed that an increase on weight per seed and, at some locations, a decrease in the number of seeds per head resulted in greater yields. Overall results indicated the combination of variety maturity and planting date must be selected on a location and seasonal climate conditions basis.