Genetic Divergence of Cocoa (Theobroma cacao L.) Genotypes Based on Comprehensive Pod and Bean Traits
Résumé
Cacao (Theobroma cacao L.) production faces significant global challenges, including low yields, severe disease incidences (e.g., Black Pod, Witches Broom), and the demand for superior quality beans. Genetic improvement is paramount for developing resilient cultivars. This study aimed to assess the magnitude of genetic variability, estimate key genetic parameters (heritability and genetic advance), and determine the phenotypic and genotypic correlations among essential agronomic traits in a diverse collection of 35 cocoa hybrids maintained in Cocoa Research Centre, Vellanikkara. A total of twelve pod and bean quantitative morphological traits including yield components were recorded. The experiment was laid out in a Completely Randomized Design (CRD) with five replications. Analysis of variance (ANOVA) revealed highly significant genetic variability for nearly all traits, confirming a rich resource for selection. High estimates of broad-sense heritability coupled with high Genetic Advance (GA) as percent of mean were observed for traits like pod weight and single wet bean weight, indicating that these characters are primarily controlled by additive gene action and selection based on phenotype will be effective. A significant positive correlations was observed between total wet bean weight and pod weight (0.66), pod length (0.64), pod breadth (0.68), weight of a single wet bean (0.69), single dry bean weight (0.69), single dry bean length (0.40), and single dry bean width (0.36) Correlation analysis identified strong positive correlations between total pod weight and other yield attributes, validating their use as reliable indirect selection criteria. These findings enable the selection of superior genotypes that combine high-yield components and quality traits, providing a critical foundation for broadening the genetic base and expediting the breeding of high-performing, disease-tolerant cocoa.