Changes in Planting Date and Variety As Strategies for Wheat Production Risks Mitigation in Alabama.

Interannual winter wheat (Triticum aestivum L.) yield changes across the Southeast U.S. might be associated with management and climate variability.  The objective of this study was to determine the effect of planting date on yield and yield components of three winter wheat cultivars in North, Central, and South Alabama. The AGS 2060, AGS 2035, and Baldwin cultivars were evaluated for yield and yield components (spike per m2, kernel weight, kernel per spike) across four planting dates at approximately 15-d intervals from 2009 to 2012. Results showed that grain yield, spikes per m2, and kernel weight declined linearly with planting delay; however, the impact changed among years and locations within a year. The interaction site and planting date was observed on the number of kernels per spike, at the northen location delayed planting resulted in a greater number of kernels per spike while the opposite occurred at the central and southern locations. Data showed at most site-years, planting planting 2 to 4 weeks later than the Extension’s best planting 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 like those during La Niña phase of ENSO, the impact of delayed planting on yield and kernel weight was the greatest for Baldwin and AGS 2035 and least for the AGS 2060. Additional data analysis through simulation modeling showed that at the north AL location, yield losses up to 12% due to delayed planting was observed during El Niño phase of ENSO (cold and wet winters) followed by 9% and 5% in La Niña and Neutral years, respectively. At the most southern location, losses ranged from 12% to 15% during Neutral years, 7% to 13% during La Niña years and 9% to 14% during El Niño years.