Variability and combinatorial ability in fruit characters of new <i>Theobroma cacao</i> hybrids in Ecuador

Abstract

In Ecuador there is a high genetic variability of Theobroma cacao L. However, its cultivation is mainly based on few materials, so it is necessary to develop and study new hybrids for its use in genetic improvement and commercial plantations. The phenotypic variability in the characteristics of the cobs was evaluated in 10 families of intraspecific cacao hybrids established in the experimental farm “Teodomira” in the province of Manabí, Ecuador, considering qualitative and quantitative descriptors. The specific combining ability (HCE) was calculated in the crosses made and the heritability of the quantitative characters. It was determined that there is a high genetic variability in the characteristics of the fruit at the inter- and intra-family level. However, most of the trees of the families analyzed have elliptical (44%) and ovoid (38%) cobs; more than 50% of the individuals presented cobs with obtuse apex, slight or absent basal constriction, medium or slight roughness, and intense yellow color pigmentation on the back; the average size of the cobs was 17.4 cm long and 8.1 cm diameter; fruit weight was between 624.3 and 422 g; seed weight per pod fluctuated between 130 and 96 g; and an average of 40 seeds per cob. The progeny obtained from the cross CCN51 × EET 103 presented the best HCE in terms of yield and seed weight. The evaluated characteristics of the cobs presented high and medium heritability (41-91%). There is a high genetic variability in the characteristics of the fruit of T. cacao, so it is possible to identify and select plants and progenies with desirable characteristics. Based on the calculated heritability, phenotypic selection is a suitable breeding method for this species.