Morphological characterization of leaf, flower, fruit and seed traits among Brazilian Theobroma L. species

Abstract

Morphological variability of four wild species, one semi-cultivated and one cultivated species of Theobroma L., indigenous to Brazil and introduced in the Bahian cocoa-growing region, was characterized based on 35 quantitative and 13 qualitative traits. T. cacao, which shows a great diversity of conserved germplasm and many published references for morphological characterization, besides of being one of the most cultivated species in Theobroma, was used for comparison as reference species. Sample size was defined for each organ evaluated and individual data set related to leaf, flower, fruit and seed analyzed by a multivariate approach. The studied species showed a large variation for all morphological traits evaluated. T. grandiflorum (Willd. ex Spreng.) Schum. and T. bicolor Humb. et Bonpl. showed the highest means for quantitative variables but were very divergent from each other considering flower and qualitative traits. These were the only species that presented similar number of seeds in comparison with T. cacao. A species with smaller means for most traits was T. obovatum Klotzsch ex Bernoulli. The four wild species show white seeds while T. cacao shows purple ones. Multivariate analysis of variance indicates significant differences between Theobroma species for individual or grouped morphological fruit traits. The results from a cluster analysis were, in a general way, congruent with botanical classification. The statistical analysis performed here was useful to identify a great variability among evaluated traits and to distinguish the most divergent variables from Theobroma species. This work provided an important contribution to morphological characterization of polymorphic traits from different organs of Theobroma species, which can help breeders in the future on the direction of interspecific crosses attempts.