A Systems Approach to Increasing Maize Grain Yield and Its Dependence On Proper Hybrid Selection.

Selecting appropriate maize hybrids remains one of the most important and challenging decisions that a maize grower makes each year. This decision is complicated by numerous considerations including yield potential, biotech traits, agronomic and disease resistance characteristics, stress tolerance, relative maturity, and seed cost. Hybrid selection for progressive maize growers who seek to increase the profitability of their farming operations through intensive crop management is even more complicated due to the importance of identifying genetics with high yield potential and responsiveness to agronomic inputs like nitrogen and increased plant density.

Through our efforts to quantify the impact from major management factors like fertility, nitrogen, hybrid, population, and foliar fungicide use on maize grain yield, we have documented that a yield increase of as much as 3.2 Mg ha^-1 can result from a systems approach that implements each of these factors in concert. Using an appropriate hybrid is a particularly essential component of this system, because not all hybrids are created equally in their ability to use nitrogen and respond positively to increased plant density. It is often difficult to identify hybrids with these characteristics from companies’ seed guides or from third-party variety testing reports, especially since hybrids with high yields under ‘standard’ levels of agronomic inputs are not always suited to increased plant density.

Our work has documented that the plant density responses of current commercial maize hybrids can vary by as much as 2.0 Mg ha^-1 (range of -1.4 to +0.6 Mg ha^-1) when plant density is increased from 79,072 plants ha^-1 to 111,195 plants ha^-1. Similarly, considerable variation for tolerance to low N (3.8 to 5.7 Mg ha^-1) and response to fertilizer N (4.5 to 6.4 Mg ha^-1) was measured. Together these parameters influence the management potential of hybrids, and their suitability to various agronomic management systems. This presentation will highlight our screening system for characterizing the management potential of current hybrids, and examples of how proper and improper hybrid placement affect the success of other management inputs like nitrogen, P fertility, and fungicide application.