Impacts of Varied Nitrogen Rates and Plant Densities On Phenotype Responses and Yield Optimization in Recent Drought-Tolerant Maize Hybrids.

Drought is one of the most significant factors limiting the yield of maize world-wide.  Maize is especially sensitive to drought if it occurs during the critical period of two weeks prior to and post silking.  Drought-tolerant hybrids, therefore, may prove helpful for increasing yields in periodic drought prone areas if they yield more when drought occurs, while remaining competitive with “conventional” hybrids when adequate moisture is available.  Little public sector data is available regarding the consequences of increased seeding rates on hybrids that claim superior drought tolerance, and no information exists concerning the critical levels of nitrogen inputs that are required for these hybrids to adequately express their drought tolerant propensity, especially at higher plant densities.  We will discuss results of a 2-year experiment conducted in NW Indiana (i.e. rainfed Eastern Cornbelt) on sandy soils prone to periodic drought stress.  Both improved drought stress tolerant (Pioneer AQUAmax ^TM) and similar-maturity “conventional” hybrids were planted at two densities and subjected to four nitrogen rates between 0 and 265 kg N ha^-1.  The detailed plant measurements that followed are the main focus of this presentation.