Maize not as heat tolerant as thought

Monday 14th Mar 2011 by theWeather Club

A scientific study has come to the surprising and rather startling conclusion that maize is rather less tolerant of heat than first thought. It has always been assumed that because of its abundance in the warmer regions of the world, it would have a considerable tolerance to rising temperatures, thus providing some protection against the effects of global warming.

Scientists found that under drought conditions, a 1°C rise in temperature could cut yields from three quarters of Africa's maize-growing regions by at least 20%. Even with adequate amounts of rainfall, 65% of the crops would suffer losses. Researchers combined data from 20,000 trials in sub-Saharan Africa with information from weather stations across the continent. "The pronounced effect of heat on maize was surprising because we assumed maize to be among the more heat-tolerant crops," said researcher Dr Marianne Banziger, from the International Maize and Wheat Improvement Centre based in El Batan, Mexico. "Essentially, the longer a maize crop is exposed to temperatures above 30° C, the more the yield declines. The effect is even larger if drought and heat come together, which is expected to happen more frequently with climate change in Africa, Asia, or Central America."

The findings are important as maize is one of the world's staple foods, especially in poorer countries. If it is less able than thought to cope with rising temperatures it could have serious consequences for predictions of global food production capability, and in turn for food production policies in countries around the world. "Projections of climate change impacts on food production have been hampered by not knowing exactly how crops fair when it gets hot," said co-author Dr David Lobell from Stanford University in California. "This study helps to clear that issue up, at least for one important crop."

Most previous research on the impact of climate change on agriculture has used crop data from the temperate regions of North America and Europe. But as the researchers have pointed out the results may not be transferable to other parts of the globe. "When you take a model that has been developed with data from one kind of environment, such as temperate climate, and apply it to the rest of the world, there are lots of things that can go wrong," said Dr Lobell. Armed with this new data scientists are now better placed to start asking the right question about future maize production. The answers to which are extremely important to an enormous - and increasing - number of people.