Effect of Planting Date and Cultivar On Corn Yield in the Mississippi Delta.

As corn production continues in the Mississippi Delta, a multiple-year research project was initiated in 2009 to evaluate the interaction of planting date, nitrogen (N) rate, and cultivar on grain production, yield components, and plant characteristics.  Highly variable weather conditions can lead to planting dates as early as late February and also can result in plantings in late-April to early-May.  A factorial arrangement of four planting dates (March 6, March 20, April 6, and April 20), two N rates (202 and 269 kg N ha^-1), and two cultivars (Pioneer ‘1615 HR’ and DeKalb ‘DKC 64-79’) was replicated six times at the Delta Research and Extension Center at Stoneville, MS on Bosket very fine sandy loam (Mollic Hapludalfs) and Dundee silty clay loam (Typic Endoaqualfs).  Plantings dates in 2009 corresponded well to the windows of opportunity available to producers during the spring.  Increasing N from 202 to 269 kg N ha^-1 increased grain yields of both cultivars at each planting date except for the April 20 planting date and the DeKalb cultivar that did not respond to increased N.  At the higher N rate, Pioneer 1615HR produced the highest yields (14.52 Mg ha^-1, 231.5 bu/acre) with the March 20 planting date while DeKalb DKC 64-79 reached its highest yields (13.76 Mg ha^-1, 219.4 bu/acre) when planted April 6.  The April 20 planting date resulted in acceptable yields in 2009 with adequate rainfall in July and August.  The earliest plating dates had to withstand cooler temperatures that delayed early plant development.  There was some lodging in the later plantings of the DeKalb cultivar especially with the April 20 planting.  Data for harvest moisture, test weight, seed weight, ear height, and ear samples were collected with data to still be summarized.