allAfrica.com: Africa: Can Crops Be Climate-Proofed? (Page 1 of 2)

Climate change threatens food crops across the world. Now scientists are re-focusing their efforts on crop resilience, rather than yields.

Among the most worrying aspects of climate change is its effects on the world's food supply. The worst-case scenario is stark: Africa's Sahel region will produce fewer cereals, rice cultivation in Asia will be under threat, there will be fewer vegetables -- with potatoes and beans potentially wiped out -- and livestock and fisheries will be severely stressed.

Climate change is making crop scientists review their research agenda. Until now, their main focus was on improving yields. But with successive International Panel on Climate Change (IPCC) reports warning that increased droughts and floods will shift crop systems, 'climate-proofing' of crops has become crucial. The Consultative Group on International Agricultural Research (CGIAR) institutes are now investigating how to make crops' more resilient to environment stresses.

Working blind

But efforts are hampered because few climate models predict changes for individual regions, making it difficult to predict how climate change will affect growth and yields of specific crops in each region.

"A partnership between climatologists and crop scientists will be valuable in developing regional analogues," says Martin Parry, IPCC co-chair and a scientist at the UK-based Hadley Centre for Climate Prediction and Research.

And the need is urgent. At a meeting of CGIAR institutes in Hyderabad, India, in November 2007, Parry said that the estimated window for implementing mitigation and adaptation programmes has shrunk from 30-40 years to 15.

He advised CGIAR scientists to put climate change at the heart of research programmes.

Others agree. As Kwesi Atta-Krah, deputy director-general of the Italy-based research organisation Biodiversity International says, "Plant breeders now need to focus on the future as well as the present, and use the vast genetic resources in gene banks and in the wild that hold potential for adaptation of major crops to a changing climate."

Rice crops most vulnerable

Rice crops are most vulnerable to global warming. Studies worldwide show that rising carbon dioxide levels may initially increase growth, but the benefit is temporary. Rising temperatures make rice spikelets -- the slender branches containing rice flowers -- sterile, and grain yields will fall.

Asia and sub-Saharan Africa will be amongst the most severely affected by climate change. About 90 per cent of the world's rice is grown and consumed in Asia (where 70 per cent of the world's poor live), and sub-Saharan Africa is the world's fastest growing rice consumer. The most vulnerable agricultural systems are the rain-fed uplands and lowlands that form almost 80 per cent of total rice land in Africa.

Reiner Wassman, coordinator of the Rice and Climate Change Consortium at the International Rice Research Institute (IRRI) in the Philippines, says IRRI strategies should include breeding rice that can survive climate change. He wants to see plants that can tolerate higher temperatures and/or flooding, that flower in the mornings before temperatures rise, and that transpire (lose water through evaporation from leaves) more efficiently to cool the air around them.

His hopes are buoyed by IRRI's latest research into the rice line 'sub1', which survived submersion for 17 days (see Scientists create flood-resistant rice). The line could provide genes for flood tolerance.

In Africa, the Africa Rice Centre (WARDA) is focusing on its NERICA (New Rice for Africa) varieties. These combine traits of Africa's Oryza glaberrima -- such as drought and local disease tolerance -- with the high yields of Asia's Oryza sativa.

Looming disaster for wheat?

Drought is also a big concern for the International Maize and Wheat Improvement Centre (CIMMYT) in El Batan, Mexico. The IPCC's predictions of increasing droughts spell disaster for half of the developing world's wheat growing areas.

The problem is particularly acute in central and west Africa, where the poor depend on wheat but get an annual rainfall of less than 350 mm, says CIMMYT scientist Rodomiro Ortiz.

CIMMYT has launched a hunt for drought tolerance in wild wheats and 'landraces' -- traditional crops that have adapted to local conditions over centuries. The centre is also teaming up with the Japan International Research Centre for Agricultural Sciences to map drought-tolerant genes in wheat and maize.

CIMMYT is using its findings in both traditional breeding and genetic engineering programmes. For example, researchers are working on genetically engineered wheat containing the DREB gene of Arabidopsis thaliana -- a relative of mustard plants -- that may confer tolerance to drought, saline soils and low temperatures. CIMMYT is testing yields of genetically engineered plants with the DREB gene under varying water stress.

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