Dichotomous key determining varietal groups of yam species Dioscorea alata L.

Yam is an important food crop in Côte d'Ivoire. Nevertheless, its production is facing many constraints including the inability to distinguish cultivated varieties from one another. Thus, different varieties and species are designated by the same names from one region to the other and vice versa, the same varieties are called differently. The absence of major descriptors, which are easy to use is the main cause of this confusion. The objective of this study is to propose agro-morphological descriptors easy to identify, for a better determination of yam varieties of D. alata. A total of 91 accessions of yam of D. alata species were used. These accessions were observed using morphological parameter. Eight simple agro-morphological descriptors which are easy to describe were identified as major dichotomous keys for the determination of the D. alata species. These characters have been selected based on the discrimination they permit to operate. Using them, four varietal groups were formed: Pyramid, Douoblé, Brazo and Bêtê-Bêtê.