Analysis of agro-morphological variability and inter-trait relationships in Ghanaian groundnut (Arachis hypogaea L.) accessions

Germplasm characterization and evaluation are essential for the genetic improvement of crops. In this study, a collection of 204 groundnut accessions including 13 checks held by Plant Genetic Resources Research Institute, Ghana were evaluated under optimal conditions for 2 years. The objectives were to characterize the groundnut collection using 18 qualitative and 14 quantitative traits and to determine the relationships between the traits. Combined analysis of variance based on augmented design revealed significant differences (P < 0.05) among the accessions for majority of the traits. Results of principal component analysis showed that all the quantitative traits were relevant in discriminating the accessions. Primary seed colour was the most diverse qualitative trait based on Shannon diversity index (n = 0.77). Frequency distribution analysis showed predominance of decumbent growth habit and pale tan seeds. Cluster analysis using qualitative traits identified five major groups of accessions and three each based on quantitative traits and joint analysis of quantitative and qualitative traits. Number of main branches (NMB) and pod width (PW) appeared the most important traits with positive contribution to yield based on correlation and path coefficient analysis. Ten promising trait-specific accessions were identified for earliness along with desirable pod and seed traits. GH 9672 and GH 9665 were identified as promising for higher grain and fodder yield. Five accessions (GH 9833, GH 9829, GH 9830, GH 9835 and GH 9750) produced similar to 5-30% more grain yield than the best check. This study underscored ample phenotypic variation that would ultimately be exploited for genetic improvement of groundnut.