Multi-year Genetic Estimates of Quantitative Traits and Intra-specific Diversity of Some Sphenostylis stenocarpa Accessions for Reliable Selection and Characterization

Abstract

Where molecular markers strategies are limiting, phenotypic trait(s) with consistent performances over years may provide trustworthy description for crop species diversity. Twenty-one African yam bean (AYB) accessions were collected from the Genetic Resources Centre, International Institute of Tropical Agriculture, Ibadan, Nigeria. The same were evaluated on the field using randomized complete block design (RCBD) of three replications for four years at the Teaching and Research Farm of the Ladoke Akintola University, Ogbomoso, Nigeria. The 4-year data were combined and treated as a mixed model of factorial in RCBD. Analysis of variance generated components of variance and discriminatory significance of traits for phenotypic diversity were tested using STEPDISC procedure in SAS. Accessions varied significantly (p ≤ 0.05) for 13 characters. Broad-sense heritability ranged between 0.55 (days to 50% flowering) and 0.99 (number of pods/plant and oil content). Number of pods/plant, pod length, protein and oil content had high repeatability values. TSs118 had the highest value for seed yield, TSs119 had the highest oil content, while TSs109 had the highest value for protein content. Mean similarity coefficient among the 21 accessions by Gower genetic distance was 0.72. The 21 accessions were grouped into three distinct clusters. Accessions in cluster I had the least number of days to 50% flowering and maturity, but the highest protein content. Cluster II was notable for higher pod length and seed numbers. This research revealed stability status of phenotypic traits for selection and identified reliable traits for AYB description and characterization.