In Situ
Maize Conservation in Oaxaca,
Mexico: What Have
We Learned?
The loss of maize landraces may have detrimental consequences, not only for the conservation of genetic resources but for the welfare of farmers who grow them.
The relationship between lost landraces and diminished farmer welfare was a key finding from a five-year study funded by Canada's International Development Research Centre (IDRC). Researchers aimed to identify and evaluate interventions that would help smallholders in the Central Valleys of Oaxaca, Mexico, to conserve the diversity of maize landraces in the area. The study was undertaken by CIMMYT and the Oaxaca division of INIFAP, Mexico's national agricultural research program.
Farmers Demand Diversity
"Even when farmers want to continue growing landraces, diversity can be lost," says Mauricio Bellon, the CIMMYT social scientist who headed the study. "It's not easy for farmers to obtain seed of landraces they want to grow or to cross with their own varieties. A farmer has to know who has the variety he or she seeks, if the seed is good, and if it will do well in the field. Then the farmer has to negotiate to acquire the seed maybe not through a cash payment but through some sort of commitment to the seed seller."
The Oaxaca study revealed that helping smallholders identify the traditional varieties they want and providing them with seed of those landraces at lowered costs is one of the most important contributions institutions can make to genetic resource conservation and rural development.
The starting point for helping farmers to access and conserve diversity was to systematically collect and evaluate the biodiversity of landrace populations in six communities. The objective was not simply to review local landraces' agricultural or physical characteristics or genetic diversity, but to involve farmers.
"The challenge is to identify landraces that contribute to conserving genetic diversity and are also of interest to farmers," says Bellon. "If we can do that, and establish mechanisms for farmers to obtain seed and information, farmers will sow landraces, and maintain the evolutionary processes that are essential to conserving diversity."
If we don't understand how farmers manage genetic resources, we cannot understand the effects of introducing new maize varieties"
Farmers' Strategies
for Gaining Diversity
Researchers could not help farmers conserve genetic resources until they learned how farmers actually managed those resources. Julien Berthaud, a molecular cytogeneticist at CIMMYT, affiliated with the Institut de Recherche pour le Développement (IRD), says that farmers' management of landraces shows a high level of gene flow. Gene flow can be described as the movement of genes in and out of the population of maize landraces in the study communities with obvious implications for the diversity of those populations. Gene flow can occur through human intervention (e.g., the acquisition or exchange of seed) as well as natural intervention (e.g., pollen dispersed by insects and wind).
"There is gene flow through seed exchange among farmers in the same community, and through varieties bought in local and regional markets or within communities," he says. "There is also a flow of genes over long distances, for example among distinct races of maize at more than 200 kilometers. This flow promotes the maintenance of a full genetic base and greater resistance to stresses of all kinds."
Farmers in Oaxaca gain greater diversity by managing their landraces in three ways: by adding new varieties to their inventory, by crossing distinct varieties, and by selecting for particular characteristics in the varieties they grow. "The third strategy is used in farmer participatory breeding," says Bellon. "But to support farmers' conservation and use of diversity, we cannot limit ourselves to one strategy."
Community
Dynamics Matter
Nearly 1,000 farmers (654 men and 343 women) from six communities participated in the study, which included a survey that gathered socioeconomic and agricultural data, the collection of 152 representative samples of maize landraces in the region, an agronomic evaluation in scientist-designed and farmer-managed trials, a participatory exercise to identify a subset of landraces that captured the diversity in the larger collection, and the development of 17 "elite" landraces. Farmers participated in 30 training sessions on topics ranging from basic principles of maize reproduction and breeding to seed selection in the household and field, and seed and grain storage.
These kinds of studies are extremely important for understanding how communities maintain diversity in the maize they grow.
"If we don't understand how farmers presently manage genetic resources, we cannot really understand the effects of introducing new maize varieties," says Bellon. This question is extremely important, given recent developments in Oaxaca (see "Transgenic Maize in Mexico,"). "Much more research needs to be done," cautions Berthaud.
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For more information: Mauricio Bellon (m.bellon@cgiar.org) Julien Berthaud (j.berthaud@cgiar.org) |
August, 2004