Morphological characterization and variability study of African yam beans [Sphenostylis stenocarpa (Hochst ex A. Rich)]
Characterisation of Sphenostylis stenocarpa (Hochst ex A. Rich) Harms (African yam bean) was carried out to determine the degree of diversity in some accessions in Nigeria. Twelve accessions of S. stenocarpa collected from the International Institute for Tropical Agriculture (IITA), Ibadan, Oyo State, Nigeria, were grown for morphological variability studies in the Screenhouse facility at the Botanical garden, University of Ilorin, Nigeria. Quantitative and qualitative variables were measured 16 weeks after planting. Quantitative data were analysed using Analysis of Variance in SPSS 16.0 for Windows. Cluster analysis was conducted to group the accessions into various cluster groups. Quantitative characters such as length, width and area of terminal leaf, petiole length, number of leaves, number of branches, stem length, and stem diameter were significantly different among the accessions. Variation of leaf colour ranging from pale to deep green exists in the accessions. Stem and petiole pigmentation varied together. Stem girth was different for TSs 162 and TSs 373. Number of branches and leaves distinguishes TSs 138, 152 and 311 from the other accessions. TSs 115, 154 and 163 were morphologically comparable while TSs 41, 125, 139 and 209 had plant height, leaf length, width and area distinguishing them from the other groups. The study concluded that the differences in the accessions of S.stenocarpa could be explored in breeding programme for improved crop.
KEYWORDS: African yam bean, breeding, crop improvement, morphological characters, variability.