Abstract

Planting material from different tuber parts (proximal, medial, distal) of four yam (Dioscorea cayenensis and Dioscorea rotundata) varieties (Laboko, Gangni, Alakitcha, Gnanlabo) showed significant differ-ences in number of plants emerged and time of emergence. This result confirms the value of farmer’s variety-specific handling of seed tubers. For three out of these four farmer varieties, there were significant differences in mean value of days after planting to emergence between parts of planting materials used. For all varieties, the proximal parts sprouted earlier than the medium parts and than the distal parts, and the loss was the highest for the distal parts. The rate of emergence is of economic importance in managing yam planting material by farmers. All tubers planted emerged for both the proximal part and the entire tuber of the second harvest. There was a highly significant difference between yield performances. The joint effect of variety and seed type was highly statistically significant in determining the yield obtained by yam farmers in Benin. The marginal benefit was the highest for the proximal part except for Laboko for which the highest benefit was obtained from the use of the second harvest seed-type. Laboko provided also the lowest and negative benefit for the distal part.

Key words: Farmer yam-seed practices, knowledge, rate of emergence, loss, productivity, profitability.