Analysis of phenotypic variability for yield and quality traits within a collection of cassava (Manihot esculenta) genotypes

Genetic diversity is essential for crop improvement and knowledge of the genetic variability within a breeding population facilitates its future exploitation. This study examined the phenotypic and genetic variability for specific cassava key traits in a collection of 30 genotypes at five environments in Rwanda. Seventy-three percent of the variation in dry matter content (DMC) and 98% of the variation in total carotene (TC) content was explained by genotypes. The broad-sense heritability (Hbs) of TC was high (99.2%) and the predicted genetic advance (GA; %) from selection was 159.7%. The phenotypic variance coefficients for all traits were higher than the genotypic variance coefficients. The highest Hbs (%) and GA for carotenoids was an indication that conventional breeding could improve carotenoid content in cassava using simple recurrent selection. The postharvest physiological deterioration (PPD) showed significant (p < 0.05) negative correlation and interrelation with TC and DMC, indicating that the high-TC and low-DMC cultivars could have delayed PPD. The higher-TC genotypes could be used to improve TC in the cassava population and consequently could contribute to the development of delayed-PPD cultivars. The results confirm that there is useful variation for key traits within the collection that could be indicative of a broad range of useful variability in natural populations, landraces and cultivars that could be exploited for breeding.