Morphological diversity analysis of African yam bean (Sphenostylis stenocarpa Hochst. ex A. Rich.) Harms and prospects for utilization in germplasm conservation and breeding

• Published in: Genetic resources and crop evolution 2012-06, Vol.59 (5), p.927-936
• Main Authors: Adewale, B. D, Dumet, D. J, Vroh-Bi, I, Kehinde, O. B, Ojo, D. K, Adegbite, A. E, Franco, J
• Format: Article
• Language: English
• Subjects: Agriculture; agronomic traits; Agronomy; Biomedical and Life Sciences; Breeding; Cluster analysis; Clustering; Color; Conservation; Dehiscence; Flowering; Food availability; Food security; Genetic diversity; genetic variation; Germplasm; germplasm conservation; Life Sciences; Morphology; Pachyrhizus ahipa; Pigmentation; Plant Genetics and Genomics; Plant Physiology; Plant Sciences; Plant Systematics/Taxonomy/Biogeography; pods; Research Article; Seed set; Seeds; Sphenostylis stenocarpa; testa; Variegation
• ISSN: 0925-9864; 1573-5109
• DOI: 10.1007/s10722-011-9734-1

African yam bean (AYB, Sphenostylis stenocarpa Hochst. ex A. Rich.) Harms is a tuber and seed crop, rich in protein, with the potential to contribute to food security. To date, available information on the diversity of AYB is scarce. This study aims at understanding the genetic diversity of 79 AYB accessions of various origins. Twenty-four morphological and taxonomic features of high descriptive values were used and the diversity within the germplasm was assessed by clustering analysis. The 79 accessions differed significantly, with the similarity distances spanning from 0.0646 to 0.5720 and a mean distance of 0.2820. The accessions were grouped into five clusters of 10–26 members. Of the 24 phenotypic variables analyzed, variegation in testa color was the most discriminatory trait, classifying the accessions in the proportion of 25% with variegated to 75% with non-variegated seeds. The ranking by significance (P ≤ 0.05) of the ordinal variables of discriminating importance were in the order of pattern of testa variegation, basal color of variegated seeds, and testa basal color. The stepwise discriminant and frequency procedures in SAS identified other phenotypic variables with significant discriminatory attributes, such as pigmentation of plant parts, seed cavity ridges, and pod dehiscence. Accessions with desirable agronomic traits, such as longer pod length, high number of seeds/pod, non-shattering characteristics of pods at maturity, lower number of days to flowering, and a higher seed set percentage, were also identified in this study. These discriminatory traits are discussed and proposed for germplasm conservation and use.