Mycorrhizal fungi from Spathoglottis plicata and the use of these fungi to germinate seeds of S. plicata in vitro

Healthy roots from mature plants of terrestrial orchid, Spathoglottis plicata (Blume.) collected from Chiang Mai, Chanthaburi, Nakhon Ratchasima and Bangkok were used to isolate mycorrhizal fungi. A modification of Masuhara and Katsuya's method was employed to isolate these fungi from the peloton. Identification was based on morphological characteristics. Nuclei were stained with safranin O using Bandoni's method revealing that all isolates were binucleate. Three genera and four species of mycorrhizal fungi were identified: Epulorhiza repens, Rhizoctonia globularis, Rhizoctonia sp. and Sabacina sp. (Epulorhiza sp. anamorph). In vitro, symbiotic seed germination and development on seeds of S. plicata were tested using Epulorhiza repens and Rhizoctonia globularis. It was found that 99.2 percent of seeds inoculated with Epulorhiza repens and 96.3 percent of seeds inoculated with Rhizoctonia globularis germinated within 21 days, whereas only 15 percent of seeds incubated in the absence of fungi germinated. About 8.1 percent of seeds inoculated with Epulorhiza repens and 1.7 percent of seeds inoculated with Rhizoctonia globularis initiated leaves after 60 days of incubation, whereas in the absence of fungi they did not develop into seedlings and mortality gradually occurred. The seedlings became more mature and ready to be planted after 127 days.