IN-SITU CONSERVATION OF MAIZE IN MEXICO - GENETIC DIVERSITY AND MAIZESEED MANAGEMENT IN A TRADITIONAL COMMUNITY

Results from a study of maize varieties and seed sources in a traditio nal community in Jalisco, Mexico, raise questions about the relationsh ip between generic erosion and the introduction of varieties. The rele vance of models for in situ conservation of crop genetic resources bas ed on geographical isolation of a community is discussed The morphophe nological diversity of local materials is shown to be enhanced by intr oductions of both improved cultivars and landraces from farmers in oth er communities. On the other hand, the geographical point of reference for defining ''local'' landrace is shown to be larger than the commun ity itself: Farmers will classify seed obtained from other farmers in and outside the community as that of a local landrace if it resembles their own according to the phenotypic characteristics they use to dist inguish varieties. Maize diversity in this community is then the resul t of a certain level of introduction of genetic material and not of ge ographical isolation.