Inventory of african yam bean (Sphenostylis stenocarpa (Hochst. ex A. Rich.) Harms) diversity in some Yoruba areas of Benin

The study aimed to document varietal diversity, uses, production constraints, and farmers’ selection criteria for the African yam bean (Sphenostylis stenocarpa) in Benin, identify production areas, prioritize constraints, evaluate genetic diversity, determine varietal selection criteria, and gather endogenous knowledge on cultivation practices, use, conservation, and seeds. A participatory ethnobotanical survey involving group investigations and individual surveys was conducted in ten villages in the Yoruba cultural zone of southern Benin (Plateau and Collines departments). Surveys used participatory methodologies, including group discussions with the four-square method for variety distribution, comparison matrix for constraints and preferences, and structured questionnaires for individual data from 21 households. Data included socio-demographics, varietal nomenclature, diversity loss, uses, preferences, and constraints, with statistical analysis of traits frequency entered in Excel. Eleven local varieties were identified, differentiated by seed color (41.7%), cooking time (25.0%), and ritual/symbolic functions (20.8%), with 2-7 varieties per village. Main constraints included pod rot (17.24%), lack of trees for intercropping (17.24%), and market outlets (12.06%). Diversity loss showed high erosion (up to 100% in some villages). Uses were domestic consumption (100%) and rituals (50%). Preferences focused on seed availability (61.9%). Production declined in 81% of producers, with solutions proposed as upright varieties (42.9%) and improved practices (37.1%). Local knowledge is crucial for conservation despite erosion; revitalization requires farmer-led selection, adapted varieties, and institutional support, with biochemical/molecular characterization recommended for true diversity assessment.