Micropropagation of an Australian terrestrial orchid Diuris longifolia R. Br

Abstract

A method is described for the in vitro propagation of the Australian terrestrial orchid Diuris longifolia R. Br. Explants from inflorescences of D. longifolia were successfully cultured on modified Burgeffs N3f containing the cytokinin N6 benzyladenine. Protocorm-like bodies formed after 49 days on explants taken from the basal section of flower buds and axillary nodes from inflorescences. Root formation occurred 70 days after transfer of 10-20-rnm-long shoots onto medium containing coconut water and no cytokinin, and rooted plantlets were transferred to soil and acclimatised 2-3 weeks later. Rooting of in vitro shoots was improved by increasing the sucrose concentration to 40 g/L or by addition of 0.05% activated charcoal to the culture medium. Plantlets developed flowering stems in vitro and flowered in pots 11 months after excision of explants from the parent plant. This tissue culture method has been successfully applied to the propagation of D. purdiei, a rare and threatened species from Western Australia.