Estimates of combining ability for cocoa fat content in seeds of parental clones and their hybrids in diallel crosses

Cocoa butter or fat is one of the most valuable products extracted from cocoa beans. It is used for the manufacture of chocolate, pharmaceutical, and cosmetic products. Breeding programs in the world are trying to develop cocoa varieties with a high fat content and productivity to increase the production of fat per hectare. In a laborary, we extracted cocoa fat from seeds of 16 parental clonal genotypes and their 62 hybrid combinations tested in a field experiment. The hybrids plants were obtained by controlled pollination using a partial diallel mating design. Analysis of variance, Scott–Knott mean comparison tests, a test of the general combining ability (GCA) of parental clones, and tests of the specific combining ability (SCA) of hybrid combinations were performed. Significant differences were obtained for fat content in seed of the parental plants. Genotypes from the Amazon region demonstrated a higher fat content, whereas genotypes from Trinidad (Trinitario) and Criollo exhibited lower values. Diallel analysis indicated that both additive and nonadditive effects were relevant to fat content, with the additive effects having a greater influence. Regarding the fat content, it is recommended to use the parents SCA 6, CEPEC 89, BE 4, CCN 51, ICS 9, and P4B for crosses aiming to increase fat, whereas the genotypes EEG 29, CCN 10, and OC 67 should be avoided because of their tendency to reduce fat content.