Micropropagation of some Myrtaceae species which show potential as 'new' ornamental plants

Abstract

Eleven species of Australian Myrtaceae were evaluated for their ability to be cultured in vitro. Ten species produced axillary shoots (microcuttings) suitable for inducing roots in vitro. Microcuttings of 9 species successfully developed roots and were transferred to soil culture in a glasshouse, where plants grew normally. Nodal explants were grown on a modified Murashige and Skoog (MS) medium supplemented with varying concentrations of 6-benzylaminopurine (BAP), to study shoot proliferation. Beaufortia heterophylla Turcz. explants did not respond to BAP, and all explants eventually died. The rate of shoot proliferation for the other species varied according to BAP concentration. Microcuttings of 10 species were grown on a modified half-strength MS medium supplemented with varying concentrations of the auxins indole-3-butyric acid (IBA) and naphthaleneacetic acid (NAA), to induce root formation. An increase in root number and an associated decrease in root length was observed as the concentration of IBA and NAA was increased. Verticordia muelleriana E. Pritzel did not develop roots in any treatment. Chamelaucium uncinatum Schauer cv. Purple Pride, Kunzea parvifolia Schauer, K. pulchella (Lindl.) A. S. George, Leptospermum rotundifolium (Maiden & Betche) F. Rodway ex Cheel, Verticordia drunzmondii Schauer, V. graizdis J. L. Drumm., V. hughanii F. Muell., V. nzonaclelpha Turcz., and V. roeii Endl. microcuttings developed roots both with and without added auxins. Roots that formed on microcuttings at higher auxin concentrations were generally thicker and slower in growth.