Abstract
Colocasia esculenta (L.) Schott and Xanthosoma sagittifolium (L.) Schott, collectively referred to as cocoyam, are two starchy edible tuber crops. In spite of their great nutritional, medicinal and industrial potential, a major setback in their commercial utilization is the lack of consistent genetic information on several traits of economic and dietary importance as such data is presently unavailable due to lack of commercial varieties, in situ reserves, and genetic and nutritional characterization of most accessions. To better understand the spectrum of divergence as well as identify suitable genetic resources, as precursors to enhancing systematic improvement and selection programmes that would support efficient conservation strategies and industrial utilization of the crop, twenty C. esculenta and thirty X. sagittifolium accessions were evaluated using taxonomic and agronomic fingerprinting based on twenty qualitative and eight quantitative descriptor states and the data derived were analyzed using appropriate statistical packages. Twelve of the qualitative descriptors found useful in differentiating and grouping the cocoyam accessions into clusters revealed 83.58% and 79.49%, respectively, of total variations. Analysis of variance test equally demonstrated significant variations (p ≤ 0.05) among the quantitative traits, with those showing discrimination appraised from factor analysis being plant span, plant height, number of suckers, corm weight, number of cormels, weight of cormels and yield, which accounted for 82.41% and 78.01%, respectively. In addition, variations were observed in the profiles of the two cocoyam species when standard analytical techniques were used for evaluation on the basis of their nutritional signatures, with significantly higher levels of nutrients detected among the representative accessions of X. sagittifolium than those of C. esculenta. Collectively, these findings demonstrate a genetically diverse cocoyam population, which implies that the accessions are derived from several lineages, having been introduced at different times through many different routes and, possibly, by multiple agents. Together, this preliminary information is highly informative and would serve as useful guide for tracing the evolutionary relationships among the two species of cocoyam. It can also be used for creating awareness on the high dietary value of the crop to increase its utilization for food and nutritional security in sub-Saharan Africa.