Farmers' Varietal Identification in a Reference Sample of Local Phaseolus Species in the Sierra Juárez, Oaxaca, Mexico

Farmers' Varietal Identification in a Reference Sample of Local Phaseolus Species in the Sierra Juárez, Oaxaca, Mexico. Farmer-named varieties are often the basis of in situ diversity assessment, collections for ex situ conservation, and on-farm improvement programs. Such varieties play an important role in sustainable agriculture because of their adaptation to local environmental conditions and consumer tastes. The importance of these varieties has stimulated interest in understanding farmers' varietal classifications. We investigated the empirical basis of, and agreement among, farmers' bean variety classification in a community in the Sierra Juárez, Oaxaca, Mexico. A reference sample of 300 local seeds of three Phaseolus species was sorted by nine farmers into named varieties. Nuclear and chloroplast microsatellite markers and seed morphology data were used to a) establish species identities; and test the hypotheses that b) farmer varieties reflect morphological and genetic structures; and c) there is agreement among farmers in variety classification. Because all farmers sorted the same set of seeds the variation in individual farmers' classifications could be documented and compared. Our results indicate an empirical basis for farmer varieties, but without stringent classification rules. Varietal names underestimated diversity present at the community level because of the intravarietal variation present in farmer classifications. There was low classification agreement among farmers, although broad morphological and genetic patterns were present. The variation in farmers' classifications of this Phaseolus diversity resulted in both synonymy and homonymy across classifications. The goal of farmers may not be to maintain the same variety across households, but to form a version of a broad type that best fits their own needs and circumstances at one point in space and time. Thus, in both work with farmers and collections of their Phaseolus varieties for ex situ conservation it should not be assumed that same-named seed lots are redundant units of diversity. Morphological and/or molecular data should, therefore, supplement farmer varietal names in assessments of in situ crop diversity, while ex situ collections would benefit from the inclusion of multiple accessions of the same variety from different farmers, repeated over time.