China has set up 11 research stations in Africa to boost yields of staple crops.

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Those that have done best are now moving away from staple crops to higher-value things such as flowers and fruit.

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Because rice is grown in heavily irrigated conditions, it is more susceptible than other staple crops to environmental pollutants in irrigation water.

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All three are used to fertilize corn, soybeans and other staple crops.

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Staple crops like wheat, soy bean, rice and potato -- things that would provide carbohydrates, protein and fat -- they're the final end point.

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The result, in the case of staple crops, is higher yields in tougher conditions: a hectare of rice, a C3 plant, produces a harvest of no more than eight tonnes, whereas maize, a C4 plant, yields as much as 12 tonnes.

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The plague threatened pasture for livestock and rice crops - the main staple in Madagascar, the FAO said.

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