Modern US corn is more susceptible to extreme heat stress than corn of 80 years ago

What is it about?

Since the beginning of modern corn breeding in the 1930s, corn yields have steadily increased, becoming one of the three main cereal crops worldwide. At the same time, changes in how farmers manage their crops and global climate change have changed the environments in which corn grows. Corn yields decrease when exposed to temperatures over 30 °C. Our research used historical records of yield trials for US corn hybrids to examine whether tolerance to heat stress has changed during the past 80 years. We discovered that although tolerance to mildly stressful temperatures has improved, at the same time, tolerance to extreme temperatures has decreased.

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Photo by Taylor Siebert on Unsplash

Photo by Taylor Siebert on Unsplash

Why is it important?

Our study is the first to explicitly incorporate genetics into an analysis of changes in the heat tolerance of corn over time, which enabled us identify small genetic trends in heat tolerance. Heat stress has a detrimental effect on corn yields, and this key stressor is predicted to increase over the coming decades due to climate change. Various ways to adapt corn to these future environments are being explored by plant scientists. Our study demonstrates that heat tolerance in US corn has changed in unexpected ways. While we hypothesize that this change has been achieved mostly inadvertently be selecting for higher yields in environments that have become increasingly warmer, it also demonstrates the possibility for plant breeders to introduce intentional changes that would increase heat tolerance to help stabilize corn yields in future (hotter) environments.