Some examples of Burrus corn hybrids that are "flex ear" and perform better at lower planting populations are:
However, at higher plant populations or growing conditions that consist of higher amounts of stress, “flex ear” hybrids may have a reduced ear size. On the other hand, “fixed ear” hybrids are thought to not perform as well at lower populations because they are not as easily able to increase their ear size. The “fixed ear” hybrids tend to respond well at higher planting populations.
The Burrus corn lineup consists of flex, intermediate, and fixed ear types. If you are not sure what type of ear your corn hybrid has, you can refer to the Think Burrus Product Guide.