Assessment of Genetic Diversity Analysis in African Yam Bean (Sphenostylis stenocarpa Hochst Ex.A.Rich Harms) using Qualitative and Quantitative Attributes

Abstract

This study evaluated the genetic diversity of 18 African Yam Bean (Sphenostylis stenocarpa) accessions from the IITA germplasm in Ibadan, Nigeria, using nine qualitative traits. The experiment was conducted behind the Biological Science Block at the University of Calabar, following a Randomized Complete Block Design (RCBD) with three replicates. Qualitative traits were observed and recorded based on the descriptors for African Yam Bean, while quantitative traits were measured using metric tools like rulers, vernier calipers, and weighing scales. Data were analyzed using Analysis of Variance (ANOVA) and Least Significant Difference (LSD) tests via GenStat Discovery Edition 4 and PASW version 20.0 software. Results indicated minimal variation in morphological traits such as days to 50% seedling emergence, vine length, leaf number, leaf dimensions, peduncle and petiole length, and days to 50% flowering across accessions. Leaf color varied, ranging from light green to dark and pale green, with accession TSs 285 showing pale green leaves. Seed shapes varied from round/globular to oval or oblong, and all accessions except TSs 33 had seed cavities. Accessions TSs 266 and TSs 38 performed better in most parameters, except for days to 50% flowering and leaf count. Significant differences (P < 0.05) were observed in traits like days to 50% emergence, days to 50% flowering, leaf color, pod dehiscence, seed shape, seed cavity presence, testa splitting, and texture. However, no significant differences were noted for hypocotyl pigmentation and pod dehiscence. Accession TSs 266 excelled in traits such as vine length, terminal leaf width, peduncle length, and pod number per plant, showing optimal adaptation to the climatic and agro-geological conditions of Cross River State.