Modelling and Correlation on Yield-Related Traits in 25 African Yam Bean (<i>Sphenostylis stenocarpa</i>) Genotypes under Humid Climate

Abstract

African Yam Beans (AYB) (Sphenostylis stenocarpa) is an underutilized tropical legume with little or no breeding record for upgrading productivity. Climatic factors are among the key challenges of productivity in the tropical ecology. Yield-related trait plays a crucial role in yield improvement. This study aimed to develop a model for path analysis and correlation studies of 25 AYB genotypes under humid environment for the 2021 and 2022 seasons. A field experiment was conducted at the University of Calabar Teaching and Research Farm in Cross River State, Nigeria. The research employed a randomized complete block design (RCBD) with three replications and 25 treatments. The study focused on integrating structural equation modelling (SEM) with multi-trait association studies (MTAs) to explore the genetic interdependencies among yield-related traits. Significant positive genotypic correlations were found between seed yield and traits such as peduncle length (rg = 1.000), pod weight (rg = 0.964), and seed weight (rg = 0.926). At the same time, the flower abortion rate exhibited a negative correlation (rg = -1.000). The phenotypic correlations followed a similar pattern, confirming the strong genetic basis for these associations. The application of SEM-GWAS proved to be a very robust tool for understanding complex trait associations in African yam bean, revealing direct and indirect contributions to seed yield. These findings offer invaluable insights for future breeding programs aimed at yield improvement and genetic enhancement of African Yam Bean. This underscores the significance of selecting of traits with strong genetic correlations in crop improvement studies.