Drought Tolerant Corn Under Varying Irrigation and Seeding Rates.

Corn is a major irrigated crop in the Southern High Plains of the United States.  With declining aquifer levels and implemented water pumping restrictions, it is important to examine new commercially available drought tolerant corn hybrids under varying irrigation and seeding rates.  Two separate studies were planted in 2011 at the North Plains Research Field (NPRF) in Etter, TX, examining the first generation drought tolerant hybrid corn technologies from Pioneer and Syngenta.  Irrigation rates were set at 100%, 75%, 50% and 40% of evapotranspiration (ET).  A low, medium and high population was selected for each company.  The highest water use efficiency (WUE) was observed at 75% ET with 16,200 seeds ha^-1 at 19.5 kg ha^-1 mm^-1 of total water.  Population effects were related to hybrids and irrigation level.  In general, the commercially available drought tolerant hybrids showed an increase in yield over the check hybrids at lower irrigation levels.  Pollination also improved with a drought tolerant hybrid in the 50% and 40% irrigation levels when compared with a check.  2011 was an exceptional year of drought and heat in the Southern High Plains.  This should be taken into consideration when interpreting these results.