Adventitious rooting of cuttings from the therapeutic honey plants, Leptospermum polygalifolium and L. scoparium

Abstract

High demand for therapeutic honey is driving establishment of Leptospermum (Myrtaceae) nectar plantations. Leptospermum seeds are often difficult to extract or germinate, and so methods have been sought to propagate Leptospermum from cuttings. We assessed the amenability of two high-value species, L. polygalifolium and L. scoparium, to propagation as rooted cuttings with or without the application of indole-3-butyric acid (IBA). IBA did not significantly affect average rooting percentages, although IBA occasionally increased the number of adventitious roots per rooted cutting in both species. Average rooting percentages for untreated cuttings were 92%, 88% and 93% for L. polygalifolium clones P6, P9 and P10 and 65% and 76% for L. scoparium clones S9 and S15. The cumulative capacity for plant production from three successive harvests was 95, 126 and 118 rooted cuttings per stock plant for the L. polygalifolium clones and 37 and 53 rooted cuttings per stock plant for the L. scoparium clones. L. polygalifolium and L. scoparium were found to be highly amenable to vegetative propagation, facilitating the establishment of therapeutic-honey plantations.