How will heat stress affect hybrid maize? 

The ability of crops to withstand heat is critical to the global food system’s resilience to climate change. A US study published in the open access journal PLOS Genetics by Kusmec et al. (2023) from Iowa State University suggests that trait selection through plant breeding has increased maize’s tolerance to moderate heat stress over time. However, its tolerance to severe heat stress has decreased.

Maize is vulnerable to heat stress; high temperatures can diminish crop yields, but the genetic adaptation of maize to heat over time is not well understood. In order to better understand how maize’s heat tolerance has changed over time, researchers collected 81 years of public yield trial records, including 4,730 maize hybrids. They paired maize yield data with historical weather records from the same time period and, using this data, built a model estimating genetic variation for temperature responses among maize hybrids.

The study’s findings were limited by potential confounding factors such as environmental conditions other than temperature and precipitation. Future studies are needed to better understand the potential for plant breeders to select for temperature adaptation.

“Because climate change is expected to increase the incidence of severe heat stress in particular, these findings indicate the need for more detailed genetic and physiological studies of heat tolerance and their incorporation into plant breeding efforts. They also highlight the past successes of plant breeders at adapting maize to moderate heat stress,” note the authors.