Effects of the Leaf Sheath on Stalk Strength in Maize

It has been observed that the leaf sheath of many different plants influences flexural ultimate strength. This is of particular interest for Zea mays (maize) cultivation, because the ultimate strength strongly influences the rates of brittle stalk lodging or “greensnap” failure. “Greensnap” failure in maize costs billions of dollars in lost harvests per year in the United States alone. The purpose of this study is to model the effect of the leaf sheath on the strength of maize stalks as they mature. The “DARLING” (Device for Assessing Resistance to Lodging in Grains) was used to make field measurements of stalk strength for plants with and without the leaf sheath removed. Field measurements were performed over the course of the growing season for five different Zea mays varieties. The sheath was found to have a significant effect on stalk strength. Its influence was largest for younger stalks, and became less pronounced as the stalks matured. This mirrors the effect of leaf sheath on stiffness seen in previous maize studies. The results of this study validate the need for future studies that look at how genetic and environmental factors affect the strength of maize leaf sheaths.