Illinois Researchers Say Higher Temperatures Spell Uncertainty for Sweet Corn

Few things say summer in America more than buttery corn on the cob, but as summer temperatures climb to unprecedented levels, the future of sweet corn may not be so sweet. New University of Illinois research shows sweet corn yields drop significantly with extreme heat during flowering, especially in rainfed fields in the Midwest.

Climate projections don’t just predict a handful of hot days going forward. The U.S. Global Change Research Program predicts 20 to 30 more days over 32 C [about 90 F] by mid-century across much of the U.S.   

“The reality is that producing sweet corn, one of the most popular vegetable crops in the U.S., will be more difficult in the future. We need to develop new approaches and technologies to help crops adapt to climate change,” says Daljeet Dhaliwal, former graduate research assistant and lead author on the study published in Scientific Reports, in a recent release.

Dhaliwal worked with Marty Williams, USDA-ARS ecologist and affiliate professor in the Department of Crop Sciences at Illinois, to document yield response of sweet corn to growing season temperature and precipitation over a 27-year period. Williams obtained private data from sweet corn processors for 16,040 individual fields in Illinois, Minnesota, Washington, and Wisconsin, providing a much finer resolution than similar studies in field corn using county-level data.

“Our analysis reveals that small temperature changes have a greater influence on crop yield compared to small precipitation changes for both rainfed and irrigated fields in the Midwest and Northwest, but rainfed production shows greater sensitivities,” Williams says.

He adds that extreme temperatures during flowering can influence pollen viability, fertilization, kernel abortion, and other processes.

“If there’s a bad time for extreme heat, it’s during flowering. That’s especially true in a crop where ear quality is so important. With heat stress during flowering, you can have ears with fewer kernels or very misshapen kernels that look nothing like what the consumer is expecting,” Williams says.

This study used the concept of “extreme degree days” to capture the cumulative effect of temperatures above 30 C [86 F] during flowering on sweet corn yield. Degree days are normally calculated by taking the average of high and low temperatures over a given 24-hour period. To calculate extreme degree days, Dhaliwal summed degree days over 30 C.