Simultaneous encapsulation of seed and mycorrhizal fungi for long-term storage and propagation of terrestrial orchids
2008
Sommerville, Karen D. | Siemon, John P. | Wood, Chris B. | Offord, Catherine A.
Ex situ conservation of threatened terrestrial orchids requires the simultaneous conservation of their mycorrhizal associations. A method for encapsulating both seed and fungi in alginate beads (known as encapsulation-dehydration) was applied to the storage and propagation of two endangered orchid species in NSW, Australia-Pterostylis saxicola D.L.Jones & M.A.Clem. and Diuris arenaria D.L.Jones. We tested the effect of storage duration and temperature on fungal recovery and germination potential in vitro, and recorded survival for seedlings subsequently transferred to potting mix. Storage at 23°C significantly reduced fungal recovery and germination for both species after only 3 months (P<0.05), whereas storage at 4°C significantly reduced fungal recovery for P. saxicola after 6 months (P<0.05). Storage for 6 months at -18 and -196°C had no significant effect on the fungal recovery and germination percentages of either species. All beads transferred directly from in vitro culture to potting mix resulted in the establishment of at least one seedling, and production of a healthy tuberoid, when transferred near the commencement of the natural growing season. The encapsulation-dehydration method may have a practical application for use in ex situ conservation of other terrestrial orchids, as well as their mycorrhizal fungi.
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