Investigating Hybrid Interactions with Nitrogen and Foliar Fungicides

IPNI-2012-CAN-ON32

29 Apr 2016

2015 Annual Interpretive Summary


Farmers recognize that corn hybrids can differ in their response to N fertilizer applications. This study was conducted to investigate such differences among six soon-to-be-released experimental hybrids from two major seed companies. The trial was conducted in Ridgetown, Ontario from 2012 through 2014. The hybrids were compared at two plant densities (32,000 and 42,000 plants/A) with and without an added fungicide.

Yield responses to added N fertilizer were lower in 2014 owing to growing season temperatures that were considerably below normal. Maximum yields attained in the years 2012, 2013, and 2014 were 245, 235, and 219 bu/A, respectively. Yield response to applied N varied from 56 to 125 bu/A in 2012, from 31 to 70 bu/A in 2013, and from 13 to 46 bu/A in 2014, depending on hybrid and plant density. Two hybrids consistently yielded higher than the other four in each of the three years, and tended to have higher than average agronomic efficiency as well. Mean agronomic efficiencies of these two hybrids for the years 2012, 2013 and 2014 averaged, respectively, 0.45, 0.25, and 0.15 bu of corn yield increase per lb of applied N. The effect of fungicide on grain yield interacted with hybrids and plant densities. The hybrid variability in response identified in this trial contributed to a decision by the Ontario Corn Committee to evaluate 20 selected production hybrids at eight sites at two levels of production practice, at N fertilization rates of 150 and 220 lb/A. This decision will provide producers with better information on hybrid differences in N response, strengthening their ability to select the right rate of N. The final results for 2015 are not yet available, but the research is continuing.