Corn Hybrids with High Yields Come with More Variability

Agriculture's main task is to feed the growing population, while minimizing environmental footprint. For corn breeders, this tough task means improving nitrogen-use efficiency and crowding tolerance, all while maximizing yield.

The first step, according to a new study from the University of Illinois (U of I), is understanding the genetic yield potential of current hybrids. A hybrid with high yield stability is less responsive to the environment and will perform consistently in sub-optimal and optimal conditions. A hybrid with high adaptability will yield like gangbusters when planted in optimal conditions, but may let farmers down in a bad year. The problem is that current commercial breeding programs develop their elite hybrids under optimal conditions – high levels of nitrogen fertilizer and plenty of space between rows – and only test yield responses to different crop-management practices in the pre-commercial stage. That means there is a limited understanding of each hybrid's stability and adaptability under variable conditions.

To fill the gap, the U of I researchers evaluated 101 commercially available elite hybrids at two planting densities and three nitrogen fertilizer rates across multiple years and locations. They found that the amount of applied nitrogen fertilizer had a much greater effect on yield than planting density, but they emphasize that the consistency of the yield response was more important. Hybrids that combined above-average yield under unfertilized and low-nitrogen conditions exhibited more consistent yields regardless of the environment. These workhorse hybrids would be best used in nitrogen-loss prone areas, or when yield stability is more desired.

More details are available in the U of I College of Agricultureal, Consumer and Environmental Sciences website.