In Situ Conservation of Landraces in Centers of Crop Diversity
The importance of crop germplasm found in landraces is well established, and a comprehensive international program exists to conserve this resource ex situ in gene banks and botanical gardens. Landraces are still cultivated in regions of crop domestication and diversity. In situ maintenance has been neglected by genetic resource conservation programs in part because of misconceptions about farming systems that produce landraces. This paper presents three cases of on-going maintenance of landraces by farmers who have also adopted high-input technology, including high yielding crop cultivars. These cases are potatoes (Solanum spp.) in the Andes of Peru, maize (Zea mays L.) in southern Mexico, and wheat (Triticum spp.) in western Turkey. These cases suggest that on-farm conservation of landraces can be decoupled from traditional farming practices. Factors that promote in situ conservation are the fragmentation of land holdings, marginal agricultural conditions associated with hill lands and heterogeneous soils, economic isolation, and cultural values and preference for diversity. Landraces are likely to persist in patches and islands of farming systems in regions of crop domestication and diversity, and these patches provide potential sites for conservation programs. In situ conservation may be a valuable complement to ex situ methods because it can preserve the biological and social processes of crop evolution. Research is needed on the biogeography and conservation biology of remaining landrace populations in order to plan in situ conservation.
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