Why is Corn so Short?

Why is Corn so Short?

July 3, 2012

In many areas of the state we’re seeing shorter than normal corn this year, leading to the question, "Why this year?" To explain this, I consulted with two top corn physiology experts — Bob Nielsen, extension corn specialist at Purdue University, and Tom Hoegemeyer, professor of practice in the UNL Department of Agronomy and Horticulture.

A variety of interacting factors can lead to shorter than normal corn. First, let’s look at this corn crop to date. We planted most of the crop much earlier than normal, which led to corn plants developing during a period when in most years, the seed would still be in the bag. After planting, we experienced warm daytime growing conditions and cool, almost cold nighttime temperatures.

The mature corn plant height depends on three factors:

  • amount of solar radiation on the top leaves during growth,
  • water, and
  • temperature.

We usually don’t have issues with solar radiation limitations in the western Corn Belt; this year water was more of a factor. Much of the young corn plant’s development was in drier than normal growing conditions. There was adequate moisture for growth but nothing like we have experienced in recent years.

Water availability and temperature impact growth rate. Cell division is affected much less than cell expansion, and slower growth rates lead to slower root development, further limiting water uptake and nutrients. Slower cell expansion leads to shorter internodes and smaller leaves, and this leads to less water uptake and light interception, CO2 uptake, further impacting growth. Because of these changes, we have less internode elongation and thus early planted corn tends to be shorter than later planted corn.

Will conditions leading to shorter corn impact yield? Not necessarily. More important to the final yield of this year’s crop is the heat and moisture stress that the crop is now experiencing as it moves into pollination.  With high heat forecast for the coming week, this will be a concern.

Keith Glewen
Extension Educator, Saunders County