MORPHOLOGICAL VARIATION OF CACAO (Theobroma cacao L.) FRUITS AND SEEDS FROM PLANTATIONS IN TABASCO, MEXICO

Abstract

Knowing the morphological and genetic diversity present in plantations, especially in native species, is important for the management and use of available plant resources. The objectives of the study were to determine the morphological variation of fruits and seeds of cocoa existing in commercial plantations (PL) established by seed in Tabasco, Mexico and to identify collections in PL with outstanding characteristics associated with yield. The collection of fruits was performed in 33 PL of seven municipalities from Tabasco and one municipality from Chiapas. In total, 101 trees were sampled in PL; in addition, 69 accessions from CEHUI- INIFAP and Ex-Finca el Danubio gene banks were included as reference germplasm. The characterization included 11 qualitative and 18 quantitative characteristics of the fruit and seed. Basic descriptive statistics were calculated, as well as the Pearson correlation coefficients, and a principal coordinate analysis were performed to assess the patterns of variation of the tested characteristics, to find their relationship and to identify the most discriminant traits between accessions. In PL, the dominant shape of the fruit was elongated-narrow bottom (26.8 %) followed by melon-shaped (22.1 %), and no fruits with the creole form were observed. The shape of the fruit, along with characteristics as basal constriction and scarce rugosity reflect the hybridization of cocoa between creole × foreigner from the lower Amazon that has occurred in these plantations over time. Other characteristics such as weight, length, and diameter of the fruit also presented wide ranges of variation in PL. The variation in fruit weight, ridge thickness, seed weight, mesocarp proportion, the number and total weight of seeds per fruit and mucilage pigmentation defined the spatial distribution between PL accessions. Accessions Tc29487, Tc29745, Tc29747, Tc29749 and Tc29775 presented an outstanding combination of number and total weight of seeds per fruit, proportion of mesocarp and fruit index.