Morphological Characterisation of Wild Yam (Dioscorea spp.) Accessions in Benue State

Wild yam species of the genus Dioscorea constitute important food security and cultural resources across the yam belt of North Central Nigeria, yet morphological diversity among wild Dioscorea accessions in Benue State has not been systematically characterised. This study conducted morphological characterisation of 45 wild Dioscorea accessions collected from eight Local Government Areas in Benue State. Qualitative and quantitative morphological descriptors were assessed following International Plant Genetic Resources Institute Dioscorea descriptor guidelines, covering 32 leaf, stem, tuber, and vine traits. Principal component analysis and cluster analysis were employed to assess morphological diversity. Principal component analysis extracted five principal components that together explained 71.4% of total morphological variation. The first principal component was dominated by tuber weight, tuber length, vine internode length, and leaf area. Cluster analysis grouped the 45 accessions into four major clusters, with accessions from the Oju and Obi axes forming a distinct cluster characterised by larger tubers and broader leaf lamina. Dioscorea cayenensis-rotundata was the most diverse species complex represented. Significant morphological variation was observed within and across species, indicating high intraspecific diversity. Accessions with economically desirable traits (high tuber weight and smooth tuber skin) were predominantly found in riverine communities. The study concludes that Benue State harbours considerable wild Dioscorea genetic diversity and recommends its collection, characterisation, and conservation in the National Centre for Genetic Resources and Biotechnology gene bank.

Keywords: Dioscorea, wild yam, morphological characterisation, genetic diversity, Benue State