How Important Is Nighttime Heat Stress?

June 27, 2012 04:59 AM


In a previous report, the Climate Corporation investigated the potential benefits of planting early to "beat the heat." Now, this group looks at another important factor that can have a big effect on yield.
"Most corn growers are well aware of the ways in which hot days and dry weather can negatively impact the yield potential of a crop," says director of agronomic research Jeff Hamlin. "But after years like 2010, and to a lesser extent 2011, many corn growers are becoming increasingly aware of just how important another weather event can be in determining yields: high nighttime temperatures."
The Climate Corporation analyzed Illinois and Indiana weather and yield data from the past 20 years to quantify the cost of high nighttime temperatures.  The results show high nighttime temperatures can indeed be costly.
High nighttime temperatures are associated with a reduced grain fill period. In Illinois, every 2.6°F increase above the average nighttime temperature decreased the grain fill period by a full week. In Indiana, the data showed similar results, with every 2.8°F increase above the average nighttime temperature resulting in a lost week of grain fill.
These lower grain fill periods have definite yield consequences. Over the past 20 years, Illinois corn farmers have seen yields decrease by an average of 3.6 bu. per acre for every 1°F above average nighttime temperatures during grain fill. In Indiana, the yield drop averaged 2.0 bu. per acre for every 1°F above average nighttime temperatures during grain fill.
"Until now, very few analyses have quantified the impacts of higher nighttime temperatures," Hamlin says. "This insight will help growers adjust their yield expectations more accurately as the season progresses."
For more details, you can access the report here.


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