Morphological Classification of 52 Accessions of White Yam (Dioscorea rotundata) Species at the National Root Crops Research Institute, Umudike, Abia State, Nigeria

The classification and identification of white yam (Dioscorea rotundata) species are often confusing and poorly characterized, hindering breeding programmes and conservation efforts. The objective of this paper was classification of 52 Accessions of white yam (Dioscorea rotundata) species at African yam screen house, National Root Crops Research Institute (NRCRI), Umudike, Abia State, Nigeria using appropriate standard methods. Various vegetative traits (leaf shape, stem characteristics, and leaf arrangement) and tuber traits (length, width, size, weight, shape, and thorniness) were studied. The results revealed three distinct leaf shapes: cordate (36 accessions), sagittate (8 accessions), and hastate (6 accessions). Seven accessions had pale-purple abaxial surfaces, while 14 showed glossy abaxial surfaces. Leaf arrangements were mostly alternate (42), with some opposite (8). Spines were present in 18 accessions, and 12 displayed multiple stems at the head region. Tuber traits showed significant variability among the accessions, with each exhibiting unique char acteristics. Notably, tuber weight was positively correlated with tuber length (r = 0.782, p < 0.001), tuber width (r = 0.450), and tuber size (r = 0.885). Additionally, tuber size strongly correlated with tuber length (r = 0.943) and tuber width (r = 0.435). The observed findings underscore pronounced morphological diversity within the population, elucidating underlying genetic variability and emphasizing its critical utility in precise identification and systematic classification. As this study serves as a pathway to progressively group these accessions into their respective clusters, it provides a strong foundation for yam breeding, conservation, and crop improvement programmes.