Combining ability estimation of agronomical traits in cacao F1 hybrids.

The availability of high genetic variation in plant populations plays an important role in the success of breeding programs. In cacao, a conventional breeding program through crossing between selected parents has been widely used as the simplest method to improve genetic diversity. Characterizing the variability among F1 hybrids since the early stage of growth is important in the process of assembling high-yielding varieties. This study aimed to determine the combining ability of some agronomic traits in cacao F1 hybrids derived from half-diallel crossing. A total of six F1 populations generated from a cross combination of four parental cacao clones including Sulawesi 1, Sulawesi 2, MCC 01, and MCC2 were used in the present study. The experiment was arranged in a randomized block design (RBD) with four replications. The results showed that some agronomic traits, such as plant height, leaf length, leaf width, and petiole length were significantly affected by additive gene action, while stem diameter was by non-additive gene action. Two parental clones, Sulawesi 1 and MCC 01 exhibited positive general combining ability values for all observed characters. Regardless of specific combining ability, MCC 02 x Sulawesi 1 and MCC 01 x Sulawesi 2 were cross combinations showing the highest values for plant height character. Meanwhile, the other two combinations (MCC 02 x Sulawesi 2 and MCC 01 x Sulawesi 1) had the highest values for stem diameter character. Thus, the F1 hybrids generated from these four cross combinations can be selected as genetic materials to develop new high-yielding varieties. [ABSTRACT FROM AUTHOR]