Spatial multivariate cluster analysis for defining target population of environments in West Africa for yam breeding

Yam (Dioscorea spp.) is a major staple crop with high agricultural and cultural significance for over
300 million people in West Africa. The specific objective of this study was to delineate the yam growing regions in four West African countries into homogeneous environmental clusters for yam cultivar testing. The study area covers four West African countries, Nigeria, Bénin, Ghana, and Côte d’Ivoire. Environmental, bioclimatic, edaphic, remote sensing vegetation, and socioeconomic variables were combined to define regions with similar characteristics. This information was used to quantify the impact of yam breeding programs using socioeconomic analysis. Most often trial sites for varietal testing are chosen based on convenience and ease of access. Cluster maps provide unbiased guides for site selection for varietal testing to optimally represent the target set of production environments. Results of our analysis suggest that the current breeding target areas
of the yam improvement programs are truly representative of environmental characteristics in over 90% of the yam growing regions of Nigeria and Bénin but not well represented in Ghana and Côte d’Ivoire. This analysis enables us to discover where gaps exist in breeding programs. The result of the socioeconomic analysis showed possible impact on poverty reduction in the target area and suggested problems of access to market in the production zones.