Number of pollen grains, ovules and pollen-ovule ratio in cacao clones. In: Agrotrópica v. 34 n. 2 p. 95-106, 2022.

Abstract

Cacao (Theobroma cacao L.) is a tree species, whose beans are used mainly in the chocolate manufacture. Pollination deficits have been frequently reported in cacao, impacting bean yield. In the present study, 30 cacao clones were evaluated in respect to the number of ovules and pollen grains produced. It was observed statistically significant variation among the 30 clones, for the number of pollen grains produced, ranging from 1750 to 10575 pollen grains/flower (average = 4698 pollen grains/flower). The number of ovules per flower ranged from 41.4 to 66.5 (average = 52.9 ovules/flower) and the pollen-ovule ratios from 30.7 to 186.2 (average = 88.0). There were no statistical significant differences between self-compatible and incompatible clones in respect to the pollen-ovule ratios. Considering the pollen-ovule ratios observed in this study, cacao should be classified as a facultative/ obligate autogamous, according to Cruden´s (1977) scale, despite the many evidences showing a high frequency of outcrossing in cacao. It can be concluded that there is genetic variance for the number of pollen grains and ovules in cacao, allowing breeding for those traits and contributing to the reduction of the yield gap associated to pollination deficit.