Warming turns global poor’s staple into poison

September 11th, 2009 - 2:01 pm ICT by IANS  

Sydney, Sep 11 (IANS) Cassava - the staple of 750 million impoverished people in Africa, Asia and Latin America - is turning more toxic with much smaller yields, thanks to global warming and carbon levels.
Monash University researcher Ros Gleadow and her team tested cassava and sorghum under a series of climate change scenarios to study the effect on plant nutritional quality and yield.

Both species belong to a group of plants that produce chemicals called cyanogenic glycosides, which break down to release lethal cyanide gas if the leaves are crushed or chewed.

The team grew cassava and sorghum at three different levels of CO2; just below today’s current atmospheric levels at 360 parts per million (ppm), at 550 ppm and double at 710 ppm. Current levels in the air are approximately 390 ppm.

“What we found was the amount of cyanide relative to the amount of protein increased,” Gleadow said.

“At double current CO2 levels, the level of toxin was much higher while protein levels fell. The ability of people and herbivores, such as cattle, to break down the cyanide depends largely on eating sufficient protein.”

“Anyone largely reliant on cassava for food, particularly during drought, would be especially at risk of cyanide poisoning.”

“While it was possible to use processing techniques to reduce the level of toxin in the cassava leaves, it was the 50 percent or greater drop in the number of tubers that caused most concern,” Gleadow said, according to a Monash release.

“Reducing carbon emissions wouldn’t be a bad idea either,” Gleadow said. The findings underscore the need to develop new cultivars to feed rapidly growing human populations.

The findings were published in Plant Biology.

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