Delimitation of cassava germplasm clusters in Kenya based on phenotypic traits

Abstract

Cassava (Manihot esculenta Crantz) is a staple food and more lately, cash crop in Kenya, supporting millions of stakeholders along its value chain. However, the phenotypic variability of the crop in the country is not fully understood. The objective of this study was to delimit clusters within the cassava germplasm in Kenya. The study involved 131 cassava stem cuttings of genotypes collected from seven major cassava growing counties in Kenya. Genotypes cuttings were planted in two experimental sites; namely Rongo University farm and Mawego Technical Training Institute farm. Data were collected on both quantitative and qualitative phenotypic traits, at three monthly intervals, during 3 to 12 months after planting. The data were subjected to Multivariate analysis (P<0.05). The cassava germplasm was categorised into four cluster groups based on phenotypic traits; namely Cluster 1 (72.5%), 2 (16.0%), 3 (3.1%), and 4 (8.1%) genotypes, respectively. Out of the 25 phenotypic characters assessed, a total of 11 principal components (PCs) trait sets accounted for 71.58% cumulative genetic variation (P<0.05). Furthermore, delimitation of these clusters was done based on the 11 assessed phenotypic traits. In Cluster 1, five PCs accounted for 61.7% of total variation among the genotypes. In Cluster 2, four principal components accounted for 69.2% of the variation; while in Cluster 3, two PCs explained 100% of the variation. In Cluster 4, four PCs accounted for 79.1% of the total variation among the genotypes. Delimitation of these clusters will inform targeted breeding strategies and conservation efforts.