Morphology, viability, and longevity of pollen of National Type and Trinitarian (CCN-51) clones of cocoa (Theobroma cacao L.) on the Coast of Ecuador

Abstract

The objective of this study was to determine the ideal method for in vitro germinability of Theobroma cacao L. (Malvaceae) pollen, evaluate the initial viability and longevity, and describe its morphology. In order to gather information on the morphological and viability characteristics of pollen in Theobroma cacao, flowers were collected at noon. Viability was assessed by in vitro and in vivo germination and staining. The pollen of this species is small (20 μm) and spherical to prolate spheroidal in shape. The best way to evaluate the viability in vitro was using the sucrose and agar compound. Its initial viability through germination in vitro was between 56.6 and 86.6%; with the staining method it was 100%, and by germination in vivo 40.7–58.7%. There was a moderate correlation between germination in vitro and germination in vivo (r = 0.5), but no correlation between the viability calculated by the staining method and by germination in vivo; the latter method was recommended to perform evaluations of both viability and pollen longevity. In the clones of cocoa National type, pollen quickly loses its viability, and at 240 min there was no germination; nevertheless, the pollen of clone CCN-51 has a longevity of 24 h.