Observations préliminaires de la variabilité entre quelques morphotypes de voandzou (Vigna subterranea L. Verdc., Fabaceae) de Côte d'Ivoire

Preliminary observations of variability between some morphotypes of bambara groundnut (Vigna subterranea L. Verdc., Fabaceae) from Côte d’Ivoire. Bambara groundnut (Vigna subterranea L. Verdc.), is a food legume mainly cultivated by women for whom it represents a source of income for the household. In Côte d’Ivoire, the cultivation of bambara groundnut is located in the western and northern parts of the country. These zones are characterised by contrasted agroecology including tropical rain forest and dry savanna. In these zones, bambara groundnut plays a key role in both food and culture of peoples. Four morphotypes of Côte d’Ivoire (ICU, BPR, RBU, NFU) were used in a preliminary study to assess the phenotypic variability between morphotypes. For each morphotype, 100 individuals were sampled to analyse 26 agromorphological traits selected from the list of bambara groundnut descriptors. Results of statistical analyses showed an important variability among morphotypes suggesting that 22 of these characters could be powerful to distinguish diversity among bambara groundnut morphotypes of Côte d’Ivoire. Three morphotypes (ICU, BPR and RBU) show a shorter reproductive cycle than the other (NFU). In our experimental conditions, morphotypes with a shorter reproductive cycle give a higher percentage of matured pods (87 to 95%), compared to morphotype NFU (60%). The morphotype ICU was particularly earlier, maturing 90 days after sowing (DAS), whereas the long reproductive cycle morphotype (NFU) required about 137 days. Based on the analysed agronomic traits, possibilities to improve bambara groundnut yield and to promote its cultivation in Côte d’Ivoire are discussed.