24 May 2010

Climate forces African rice revival

Scientists are reviving long-ignored African rice to cut dependence on Asian varieties that may be less able to withstand the impact of climate change on the poorest continent.

Scientists are reviving long-ignored African rice to cut dependence on Asian varieties that may be less able to withstand the impact of climate change on the poorest continent, a report said.

Historically, scientists have focused on breeding useful traits such as disease resistance from African rice into Asian rice. Now the focus is on the reverse -- using African rice as the basic crop and improving it with Asian genes. "African rice was initially ignored by mainstream research," said Koichi Futakuchi, a scientist at Africa Rice Center (AfricaRice) in a statement.

"Now for the first time, we're reversing the gene flow."

Asian and African rice are the only two cultivated species of the crop in the world but the usually higher-yielding Asian type, introduced to Africa by the Portuguese in the 16th century, has become the dominant type to meet surging demand.

African rice is 'hardy'

Africa imports 40% of its rice with import bills estimated at $3.6 billion in 2008.

"With climate change a reality, the work of developing crop varieties adapted to the changing environment is going to keep plant breeders busy for decades," AfricaRice said in a study coinciding with U.N. International Biodiversity Day on May 22.

Better breeding will help to raise yields of the African species, formally known as Oryza glaberrima, which has pear-shaped grains and a nutty flavour and was domesticated about 3 500 years ago in West Africa.

It often grows better in harsh conditions than its Asian cousin, Oryza sativa, but yields less in good soils. "Overall it is grown only in scattered pockets, near the brink of extinction," the Benin-based AfricaRice said. 

"African rice species are known for their hardiness -- their strong ability to compete with weeds, pests and diseases, volatile weather, infertile soils (including toxic levels of iron), and even human neglect," it said.

Scientists say they are overcoming problems with African rice -- the plants often fall over near maturity or scatter their seeds before harvest -- and foresee yields of 5-6 tonnes per hectare (2.471 acres) in favourable, rainfed soils.

"Farmers will only change to new varieties if they are at least as good as what they already have," said AfricaRice's Semon Mande, a rice breeder.

The panel of U.N. climate scientists has projected that between 75 and 250 million people in Africa may face extra stress on water supplies by 2020 with everything from desertification to floods. And crop yields may fall sharply.

Countries including Nigeria, Burkina Faso and Ethiopia have already used African rice varieties developed since the 1990s. In Uganda, farmers grew 35,000 hectares (86,490 acres) of African rice in 2007 and halved rice imports from 2002-07. - (Reuters Health, May 2010)


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