In vitro propagation of Epacris impressa (Epacridaceae) and the effects of clonal material

Abstract

A system of micropropagation has been developed for Epacris impressa Labill. (pink heath) (Epacridaceae), the floral emblem of Victoria, Australia. Only explants from glasshouse-grown plants treated with 1.2 g L^–1 mancozeb were established successfully in vitro. Shoot material was very sensitive to surface-sterilisation, with 0.5% NaOCl for 5 min being optimal. Multiple shooting was induced optimally on Woody Plant Medium (WPM, Lloyd and McCown 1980) with 12–25 µM of the cytokinin 2iP (6-(γ,γ-dimethylallylamino) purine). Inclusion of the auxin IBA (indole-3-butyric acid) induced callus and reduced shooting. Rooting in vitro was greatest (up to 40%) with half-strength WPM and 16 µM IBA. Clones from individual plants varied in multiple shooting response to 2iP (0–49 µM) and root induction response to auxins (IBA and NAA (α-naphthaleneacetic acid), 0–43 µM). These results suggest that explant materials are the main determinant of success in in vitro propagation and that they require individual optimisation of treatments to maximise shoot and root formation.