6 July 2011 | EN | FR
Farmers trade cowpea seeds with friends and family
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[NAIROBI] African farmers who lose their seeds in floods and droughts could restore their crop biodiversity quicker by trading local seed varieties at markets and through informal social links than by receiving seeds from aid agencies, a study suggests.
The genetic diversity of crops allows plant populations to adapt to changing environments and provides the raw materials for crop improvement programmes. It is crucial for ensuring food security through the traditional African cropping system.
But, after natural disasters, relief efforts may fail to provide a sufficiently diverse range of seeds.
"Disasters, as well as subsequent relief and recovery activities, have significant impacts on agro-biodiversity, including diversity of crops and their varieties that may exist in a farming system," said Morag Ferguson, a researcher at the Nairobi-basedInternational Institute of Tropical Agriculture and the study's lead author.
Aid agencies provide farmers with seeds from formal seed distributors, often from neighbouring countries. But these foreign seeds may fail to restore local biodiversity, putting traditional farming systems that rely on diversity at risk, according to the study published in Disasters (31 May).
The study explored cowpea (Vigna unguiculata) diversity in Gaza Province, Mozambique, following the 2000 floods and 2001 droughts, which caused some farmers to lose all their seed.
Researchers found a narrowing of the genetic base, with fewer rare alleles (alternative forms of a gene), although most of the biodiversity was regained within two and a half years.
Most farmers obtained new seeds from local markets, but these were mostly from the relief efforts and did little to restore diversity. But almost a third got them from friends and relatives in areas without floods.
"It appears that diversity was regained primarily through social networking in the form of loans or gifts of seed from friends and relatives," Ferguson told SciDev.Net.
The study recommends that future seed distribution efforts target social networks and provide more local seeds at markets.
Shem Wandiga, the director of the UNESCO-associated Centre for Science and Technology Innovation, in Nairobi, advocates storing seeds of important crops to increase genetic diversity after natural disasters.
"To prevent loss of biodiversity, collecting the germplasm of various plants and storing it for future use is the surest way of avoiding the total loss of some species," said Wandiga. But the best way to prevent biodiversity loss, he added, is to create protected areas where human activity and resource exploitation are limited.
Disasters doi: 10.1111/j.1467-7717.2011.01242.x (2011)
Jeremy Cherfas ( Italy )
11 July 2011
Could someone possibly explain to me what on earth Shem Wandiga is talking about? How do you prevent the loss of agricultural biodiversity by limiting human activity, when human activity is absolutely essential for the creation and conservation of agricultural biodiversity? The final two paragraphs of this article detract from the rest, and, I would suggest, are entirely superfluous.
S. Petzold ( Canada )
11 July 2011
Completely agree with Jeremy Cherfas. Last two paragraphs seem completely out of place here. Biodiversity and adaptation thrives only when this genetic material gets a chance to be expressed - not locked away. That's why farmer's selection, saving and use of their own local seed is so crucial to biodiversity.
Alison Tottenham ( www.tigergreen.co.uk | United Kingdom )
12 July 2011
I agree that the wording is not very clear. However, I think that the article refers to the small variations in genotype that are found in seeds saved from quite small local areas.
For instance the Centre of Diversity for the C3 Cereals in the valleys of the Tigris and Euphrates, is a relatively small area globally, but in this area are found virtually all the world's genotypes for the wheat crop. We can draw on these genotypes to breed new varieties of wheat to suit the different conditions in countries across the world.
Similarly, the crops grown from saved seed by the farmers in Africa, show a wide mix of genotypic diversity from one locality to another. This means that in any one year, the farmers can normally rely on a reasonable yield; since within the crops there will always be a percentage of plants that show high resistance to the 'disease of the year'. Of course long term floods will always reduce the oxygen content of the soil so that the plants die and rot. But if the farmers can replant with more local seed, then the usual genotypic diversity will be re-established and barring floods, the crops in following seasons will yield as well as normal.
Unfortunately, the big seed supply companies, wish to get money from all the seed sown across the globe; and therefore, have tried to ban the saving of home grown seed for the next crop. But this is definitely the best and the cheapest solution for: the farmer; healthy crops; and both the associated invertebrates and the plants (herbs/weeds) that grow in close proximity to the crop.
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