Evaluation of Nitrogen and Water Use Efficiencies On Corn Hybrids With and Without Drought Tolerance in Irrigated and Dryland Production Systems.

The drought experienced by the United States in 2012 was the most severe and extensive drought in the past 25 years.  On January 9, 2013, the USDA had declared 597 counties in 14 states primary natural disaster areas due to drought resulting in over $14 billion USD in crop insurance indemnity payments calculated by the Congressional Budget Office.  Thus, it is important to investigate how new drought tolerant corn (Zea mays L.) hybrids influence water use efficiency (WUE) in drought environments.  The objective of this research was to evaluate N use efficiency (NUE) and WUE of drought tolerant and less drought tolerant corn hybrids in irrigated and dryland production systems.  Two field experiments were established in 2013 in north-central Oklahoma as a randomized complete block design with 4 levels of hybrid and 3 levels of N rate arranged as a two-way factorial.  Two corn hybrids designated as drought tolerant (DuPont Pioneer AQUAmax brand P1498 YHR and Monsanto Dekalb Genuity DroughtGard brand DKC63-55 GENDGVT2P) were compared with two corn hybrids with less drought tolerance (DuPont Pioneer brand P1395 YHR and Monsanto Dekalb Genuity brand DKC62-09 GENVT3P).  A low, medium, or high N rate was applied preplant to each production system.  Each production system was managed differently based on best management practices; which included N rates and seeding rate.  The main effects and interaction effects of hybrid, N rate, and production system on corn grain yield, grain N, NUE, and WUE will be evaluated.  Oklahoma experienced an unseasonably cool and moist 2013 growing season that delayed corn harvest; therefore the results and conclusions are forthcoming.