By JEFF BURBRINK
Extension Educator, Purdue Extension Elkhart County
GOSHEN — Last week, I wrote about the tassel of a corn plant. This week, the subject is the silk, which part of the female reproductive organs of a corn plant. Bob Nielsen, Purdue Extension’s corn specialist, provided much of this information in his frequently updated Corny News Network website.
Each kernel is attached to one silk that emerges from the tip of the ear. The silks begin to grow longer, heading for the tip of the ear, just about the same time the first tassels begin to show themselves in a field. Silks from the butt end of the ear typically emerge first, while the silks near the tip emerge last, growing as much as 1.5 inches a day in the process.
The purpose of silk is to catch the pollen which is falling from tassels above. When viable pollen lands on the silk, it germinates, meaning it releases the male genetic material, which travels down the inside of the silk in a tunnel called a pollen tube. It generally takes less than 24 hours for the male genetic material to travel the length of the silk, reach the kernel and fertilize the ovule.
Since each silk is attached to just one kernel, each silk must receive pollen or there will be gaps among the kernels on the ear. There are a number of ways the pollination process can fail. Extreme heat (over 100 degrees) can kill pollen before it transfers its genetics. Severe droughts can cause silks to grow slower or not emerge from the ear tip. Insects such as Japanese beetle or corn rootworm beetles can clip off the silk and reduce the target for the pollen.
When fertilization does not occur on an ear, one symptom you might see is long, green silk. The silk will continue to grow for about 10 days once they emerge from the tip of the ear. Once the fertilization process is complete, the silk turns brown, signaling successful fertilization.
If you look carefully on the top of a kernel, you might see a small bump, which is scar tissue where the silk was attached to the kernel. When I show that to children, I like to say that is the kernel’s belly button.
Next week, I will wrap up this series with some information about the amazing ears of corn.
Note to editor: The attached picture shows a developing ear of corn which is not yet pollenated. Each silk is attached to one kernel on the ear.