Résumé
Plant genetic resources that have been created and maintained by farmers for millenia can be conserved through both in situ and ex situ approaches whose relative advantages and drawbacks are discussed in this paper. Dynamic management of populations with a broad genetic base, in contrasted environmental settings, is another in situ strategy that could be useful in prebreeding programs. Germplam conserved in international gene banks and farmers' fields are used complementarily by participatory plant breeders during the breeding process. Farmers' participation and the use of local versus exotic germplasm might depend on the extent of integration in local and international markets and on the environmental constraints of the agricultural systems.