Conservation-driven propagation of an epiphytic orchid (Epidendrum nocturnum) with a mycorrhizal fungus

Abstract

Seeds of an endangered epiphytic orchid from Florida (Epidendrum nocturnum Jacquin) germinated in vitro with a mycorrhizal fungus [Epulorhiza repens (Bernard) Moore] using a technique normally applied to terrestrial orchids (symbiotic seed germination). Seeds from two sources (Fakahatchee Strand, Fla. Panther NWR) were sown on either modified oats medium (MOM) or standard oat medium (SOM) and inoculated with the fungus. Significant differences in germination were detected between the two seed sources. MOM had a significant effect on mean leaf length during incubation in vitro (F(1278) = 23.81, P > 0.000), but media had no significant effect on leaf number. After 48 days in vitro, all leaf-bearing seedlings were exposed to light and then transferred to greenhouse conditions ex vitro on sterile Sphagnum moss with or without half-strength Miracle-Gro (Scotts, Port Washington, N.Y.) commercial fertilizer. After 163 days ex vitro, seedlings on Sphagnum without Miracle-Gro displayed highest survivorship (>90%), whereas Miracle-Gro-exposed seedlings from standard oat agar experienced low (44%) survivorship. Healthy seedlings with a mycotrophic capability were obtained 1 year after sowing. A total of 43 seedlings were subsequently reintroduced into the Florida Panther NWR in Nov. 2005, 16 months after sowing. The symbiotic technique may, therefore, have practical merit for conservation of E. nocturnum and other epiphytic orchids threatened with extinction.