Ethnobotany, landraces diversity and potential vitamin A rich cultivars of sweet potato (Ipomoea batatas (L.] Lam.) in southern and central Benin

Sweet potato is an important staple food in Benin, which unfortunately remains neglected by research and underutilized. To document the diversity of the crops for its sustainable conservation and use, an ethnobotanical investigation was conducted in 34 villages selected in Central and Southern Benin using participatory research approach methods and tools. For 24.59 % of the respondents, sweet potato is ranked as the sixth most important crop produced. 19.36 % of the respondents produced sweet potato for feeding purpose only, while 46.77 % of respondents are growing it for purely economic purposes. At total 12 constraints related to the sweet potato production were registered through the study area, among which eight, which represent 66.67 % of the constraints could be solve by the scientific research efforts while the rest (four constraints, 33.33 %) were purely of political order. The difficulty of farming practices (20.39 % of responses) and the sensitivity of the crop to the attack of pests and insects (19.74 % of responses) appeared as the major constraints cited by the respondents. The numbers of sweet potato varieties per village range from 2 (two) to 11 (eleven) with an average of 5 varieties per village. The Shannon diversity index of the South (4.06) is greater than the one of the Centre (4.00) and shows that South region has a relatively highest range of varieties and so suitable for the crops diversity conservation. At 65 % of similarity, the cluster analysis using UPGMA dendrogram classified the 108 sweet potato cultivars identified in eight groups corresponding to 92 morphological units based on 13 agronomic traits and culinary characteristic. Within the varietal group, it denotes some yellow (27.45 %) and orange (3.92 %) flesh variety groups of sweet potato which constitute potential source of vitamin A. The study of the vitamin A (caroten) content of those varieties is to be considered to fully exploit their nutritional potential.