Abstract

Lack of knowledge of genetic variation within cocoyam germplasm limits its effective utilization in developing ideotypes with desirable traits for various end-uses. An agro-phenotypic characterization study was therefore conducted at the Njala Agricultural Research Centre (NARC) experimental site, Sierra Leone. The aim of the study was to evaluate the level of diversity within cocoyam germplasm using factor, cluster and minimum spanning tree analyses. A total of 27 genotypes were grown in a randomized complete block design with three replications in 2013 and 2014. Forty-two agro-morphological traits measured from the genotypes were analyzed using factor analysis (FA), hierarchical cluster analysis (HCA) and minimum spanning tree (MST). Above ground, biotic stress, underground storage organ and quality traits were useful in discriminating within and between species studied. Factor analysis loaded six factors which explained 77.5% of the total agro-phenotypic variation in the dependence structure. Other factors (>6) explained the rest of the genetic variation and may not be important in cocoyam breeding programme. The dendrogram of the HCA, based on the agro-morphological traits, showed four major groups, which supports the MST and FA. This study demonstrated wide agro-phenotypic variation among cocoyam germplasm which implied their utilization in breeding program. Findings are also useful for conservation planning of cocoyam. However, further biochemical or molecular studies are needed to complement and confirm the current agro-morphological variation.

Key words: Cocoyam, agro-phenotypic characterization, multivariate tools, utilization.

Abbreviation

FA, Factor analysis; HCA, hierarchical cluster analysis; MST, minimum spanning tree; RCBD, randomized complete block design; CA, cluster analysis; BC, bud colour.