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Heat Stress Challenges Corn Yield Potential
MORGAN SCHMIDT
LUBBOCK, TEXAS
It’s crunch time in the corn field. While corn is most sensitive to drought stress during the pollination process, stress that occurs during the growth stages and into reproductive stages can also have a large effect on the overall plant health and, potential yield. If temperatures are high and moisture is limited following pollination, yield loss during grain fill may still be 3.0 to 5.8 percent per day of stress.1,2
Even with sufficient moisture, high temperatures can cause a high degree of stress on the corn plant and affect corn yield potential. Iowa State University reports that a one percent corn yield loss can occur after four consecutive days of temperatures at 93 degrees F or greater.3 A fifth day of high temperatures may cause another two percent yield loss, and on the sixth day another four percent reduction can be expected.
Severe stress leading to premature death of leaves can cause yield losses because the production of photosynthates is greatly reduced. Limited amounts of photosynthates to nourish the developing kernels may produce smaller, lighter, shallow kernels. Stress can also trigger premature kernel black layer formation which terminates kernel development and reduces grain fill.
There are few options to minimize heat stress during the grain fill stages, but growers can mitigate yield loss through fertility, and, disease management.
Adequate fertility is essential to maintaining late-season plant health. A common photosynthetic stress that can occur during late grain fill is nitrogen (N) deficiency, which may cause leaf tissues to yellow and die. Potassium (K) is a critical nutrient which moves energy from the leaves to the grain. Disease occurrence varies greatly from season to season and by the maturity stage the best option to preserve yield may be to apply a fungicide.
Through early September, farmers should closely monitor stressed fields for compromised stalk strength and adjust harvest schedules to first remove crops with high risk of stalk lodging.
Consult with your local Channel Seedsman about establishing a harvest schedule for your fields. Also, search Channel.com/AgronomyLibrary for more information about the effects of heat stress on corn. ∆
1 Lauer, J. 2006. Concerns about drought as corn pollination begins. University of Wisconsin. Field Crops 28.493-42. http://corn.agronomy.wisc.edu/.
2 Wright, J., Hicks, D., and Naeve, S. 2006. Predicting the last irrigation for corn and soybeans in central Minnesota. University of Minnesota Extension. https://www.extension.umn.edu/.
3 Elmore, R. and Taylor, E. 2011. Corn and “a big long heat wave on the way”. Iowa State University. https://crops.extension.iastate.edu.
Morgan Schmidt: Channel Agronomist
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