The Heat Is Online

Warming Will Cut Rice Yields 20% to 100%


GAINESVILLE, Florida, December 1, 2000 (ENS) - Temperature increases anticipated as part of global warming appear to reduce rice yields, a finding with worrisome implications for the third of the world's population that relies on rice as a food staple.

University of Florida (UF) researchers have found that above average temperatures interfere with the life cycle and pollination process in rice plants. Modest temperature increases predicted by some climate change scenarios would reduce rice yields by 20 to 40 percent by 2100, while the most severe predicted temperature increases could force yields to zero.

The findings are among the latest to come out of the Carbon Dioxide and Climate Change Project at UF's Institute of Food and Agricultural Sciences. Researchers involved in the project, managed in cooperation with the U.S. Department of Agriculture (USDA) and funded by UF and several federal agencies, have discovered that warmer temperatures also lead to declines in yields of peanuts, soybeans and dry beans such as kidney beans.

"I think we've demonstrated clearly that seed producing plants are much more at risk from rising temperatures than are vegetative plants such as forage plants," said Hartwell Allen, a USDA and UF crop and climate research scientist. Testing two varieties of rice - one grown in tropical climates and one from temperate areas - the scientists found that the plants produce the most rice at temperatures lower that those now found in their normal growing environments.

"We're on the downhill side for rice and soybeans now, so if there's any temperature increase the yield will slide down," said Kenneth Boote, a UF agronomy professor. Although the plants continued to flourish, they produced almost no rice at the highest temperature cycles tested, the study found. "We were hoping to find some evidence that the tropical cultivar could sustain reproductive ability at the highest temperature, but it didn't, which is bad news," said Alison Snyder, a UF graduate student.