Abstract

Yam (Dioscorea cayenensis Poir - Dioscorea rotundata Lam complex; Dioscorea alata L.) is one of the major food crops that significantly contribute to food security and poverty alleviation in Togo. To assess its cultivar diversity and document the performence of existing cultivars vis-à-vis biotic and abiotic factors, 50 villages were randomly selected throughout the country and surveyed. The study reveals the existence of important diversity. The number of cultivars varied from 5 to 51 per village, with an average of 27. Central Region and Region of Plateau were the richest (31 to 37 cultivars on average per village) and the Savannah region, which is highly affected by climate change, was the poorest (7 cultivars on average per village). Based on vernacular names and subject to synonymy, 470 cultivars of D. cayenensis - D. rotundata complex and 134 cultivars of D. alata were identified. The spatial distribution of the diversity was established using Ordinary Kriging modelling approach. The rate of cultivar loss recorded per village was high (37.01% on average) and call for urgent definition of a national strategy to preserve yam diversity in Togo. Through participatory evaluation, the performances of the identified farmer-named cultivars were documented against 21 variables of which 12 were agronomic, three were technological and six were culinary. Very few tolerant or resistant varieties were identified per biotic and abiotic stress, indicating the urgent need to establish a national yam breeding program in Togo. This would help supply the different agroecological zones with performing varieties in relation to their needs. To clarify synonymies, exhaustive germplasm collections followed by morphological and molecular characterizations have been recommended.

Key words: Cultivar loss, diversity, genetic erosion, participatory evaluation, spatial analysis, yam, Togo.