Genetic diversity and agro-morphological characterization of cassava varieties provides insight for breeding and crop improvement

Abstract

Abstract The lack of knowledge about genetic variation in cassava is a problem for Fiji’s efforts to improve its genetics. Using agro-morphological features, this study aimed to assess the genetic diversity and interrelationships among 33 cassava cultivars. A field investigation was conducted at the Dobuilevu Research Station using a randomized complete block design. Morphological analysis, based on qualitative and quantitative characteristics, divided the germplasm into three groups. In both the qualitative and quantitative trait datasets, two principal components were found to account for 36.31% and 43.45% of the total genetic variance, respectively. Qualitative features, such as branching habit and stem cortex color (r = 0.19), petiole color and root cortex color (r = 0.32), and leaf color and root shape (r = 0.40) were shown to have significant positive correlations. Similarly, quantitative parameters like starch content (r = 0.25) and the number of leaf lobes with yield (r = 0.17) showed significant associations. Based on morphological and genetic similarities, hierarchical clustering grouped the cultivars into three qualitative and five quantitative clusters. While the quantitative traits emphasized variability in yield, starch content, and iron content. The qualitative traits’ descriptive statistics revealed diverse phenotypic expressions, with dark green leaf color and cylindrical root form being the most common. These results demonstrate significant genetic variation across cassava cultivars, which can be used for genetic improvement initiatives, germplasm conservation, and short-term varietal release programs. To facilitate the development of more resilient and productive cassava cultivars, targeted breeding efforts aimed at improving yield, quality, and stress tolerance are recommended based on the significant phenotypic and genetic variation observed.