Ex vitro symbiotic seed germination of Spathoglottis plicata Blume on common orchid cultivation substrates

• This study reports a simple method for ex vitro symbiotic orchid seed germination.
• The method could be successfully used to germinate Spathoglottis plicata.
• The method effectiveness was affected by fungal isolates and cultivation substrates.
• Peat moss with Epulorhiza isolate Da-KP-0-1 was the most effective treatment.
• The method can be used by orchid growers with no access to laboratory facilities.

This study reports a simple and efficient method for symbiotic orchid seed germination. Seeds obtained from mature capsules of Spathoglottis plicata Blume were sown non-axenically on common orchid cultivation substrate (i.e., soil, coir dust, or peat moss) pre-inoculated with orchid mycorrhizal fungus, Epulorhiza isolate (=anamorph of Tulasnella; i.e., Da-KP-0-1 or Ps-KT-0-1). Fungal isolates and type of germination substrates were found to affect the effectiveness of this method. At seven weeks after sowing, peat moss inoculated with fungal isolate Da-KP-0-1 was the most effective in promoting seed germination and protocorm development. All other treatments with fungal inoculation yielded significantly higher germination percentages and average developmental stages of seeds/protocorms compared to control treatments. At nine weeks after sowing, protocorms with well-developed leaves and roots could be observed in all inoculation treatments but not in uninoculated controls. Since the established method does not require axenic condition during seed germination step, it should be accessible to professional growers, conservationists, and orchid amateurs alike. Additionally, a potentially antagonistic effect of Epulorhiza against Aspergillus contaminant growing from seeds was observed.