Failure Initiation and Propagation in Corn Stalk Tissue.

Recent advances in agricultural technology have enabled drastic increases in worldwide food production. For example, corn yields have nearly doubled over the past 30 years, and farmers currently produce over 1 billion tons of corn grain each year. However, despite such advances over 800 million people still suffer from hunger or malnutrition. Adequately, feeding the world population will require even greater increase in food production. Due to decreases in arable farm land, more plants will need to be grown on less land to meet future food demands. Unfortunately, further increase in planting density cause high rates of stalk lodging.

We investigated the problem of corn stalk lodging by applying numerous forensic and structural engineering analyses to both lodged and upright corn stalks. Our analyses demonstrated that over 90% of corn stalks fail or break within 3 cm of node line.  In this region, the stalk rind buckles or creases causing the plant to fall over. This suggests a systematic tissue weakness is at play in corn stalk.   

To understand how and why corn stalks break near the node line, we used scanning electron microscopy to investigate the cellular structure and organization of the rind tissues. The cell structure near the failure region of corn stalk is significantly different than in other regions of the stalk. Furthermore, we frequently observed internal tissue delaminations in the failure region. We hypothesize that these delaminations are the initial failure (breakage) event and that they lead to surface failures (such as creasing and cracking of rind surface) which ultimately cause the stalk to fall. Eliminating tissue delaminations or stopping there growth by modifying the material properties (e.g. bonding strength) of the rind and pith through selective breeding could prevent the initiation of stalk lodging.