Honeybush (Cyclopia spp.) anther-stigma distance and intraspecies cross compatibilities

Abstract

Species of Cyclopia are used to produce honeybush tea, a uniquely South African beverage that is rapidly growing in popularity locally and abroad. In response to warnings about ecological sustainability, the honeybush industry is transitioning from a wild-harvested source model to one relying primarily on commercial farming. To this end, honeybush genotypes are needed with improved homogeneity, sensory qualities, productivity, vigour and resistance to such pest and disease conditions as may arise in massed plantings. In support of existing honeybush breeding programmes, studies have been undertaken to answer pressing questions about honeybush reproductive anatomy and sexual compatibility. Anther-stigma distance was measured within and between honeybush genotypes in order to rule out flower heteromorphism as a cause for low seed set following hand pollination. Continuous variation in anther-stigma distance was observed for the homomorphic, leguminous flowers, suggesting the existence of a mixed-mating system. Diallel crosses were then performed by hand pollination between genotypes within three honeybush species. All three species were found to be partially self-compatible, with large variations in self-incompatibility between genotypes within species. This study provides practical recommendations with regard to the sexual propagation of select honeybush species and expands the platform of scientific research available to honeybush breeders.