Propagation potential for the conservation of Brackenridgea zanguebarica Oliv., a critically endangered plant species endemic to Vhembe District in Limpopo Province (South Africa)
Brackenridgea zanguebarica Oliv. is an important multipurpose tree valued for its medicinal uses in Vhembe District. The unsustainable harvesting coupled with poor seed germination in the wild is threatening its regeneration; which poses a challenge in efforts to its conservation. This study was conducted to identify suitable methods for propagating B. zanguebarica species using seeds and stem cuttings. Seeds propagation was carried out to evaluate the effect of various pre-treatments. Vegetative propagation was tested to assess if B. zanguebarica could be successfully propagated via stem cuttings with appropriate treatments. The results showed that B. zanguebarica seeds did not germinate at all under any of the conditions tested. Stem cuttings presented a possibility of propagating this species despite the poor results obtained, where 51% of cuttings across all treatment produced buds and 17% only developed leaves without any root development. The growth media had insignificant (P > 0.05) effect on some vegetative growth parameters, while growth hormones showed significant (P < 0.05) effect in all the vegetative growth parameters of stem cuttings where IAA performed better than IBA and NNA. However, their interaction were significant (P < 0.05) on all the growth parameters of Brackenridgea zanguebarica stem cuttings except on the percentage of cuttings that produced buds (P = 0.107). The findings showed that B. zanguebarica is difficult to propagate sexually and asexually, hence, further studies are needed to identify suitable methods for both seed and vegetative propagation of this plant
