Symbiotic propagation of seedlings of Cyrtopodium glutiniferum Raddi (Orchidaceae)

• Published in: Acta Botânica Brasílica Vol. 27; no. 3; pp. 590 - 596
• Main Authors: Guimarães, Fernanda Aparecida Rodrigues, Pereira, Marlon Corrêa, Felício, Cristiane da Silva, Torres, Denise Pereira, Oliveira, Sabrina Feliciano, Veloso, Tomás Gomes Reis, Kasuya, Maria Catarina Megumi
• Format: Journal Article
• Language: English
• Published: Sociedade Botânica do Brasil 01-09-2013
• Subjects: Epulorhiza sp; fern fiber; orchid; substrate; symbiosis
• ISSN: 0102-3306; 1677-941X; 0102-3306
• DOI: 10.1590/S0102-33062013000300016

In nature, orchid seeds obtain the nutrients necessary for germination by degrading intracellular fungal structures formed after colonization of the embryo by mycorrhizal fungi. Protocols for asymbiotic germination of orchid seeds typically use media with high concentrations of soluble carbohydrate and minerals. However, when reintroduced into the field, seedlings obtained via asymbiotic germination have lower survival rates than do seedlings obtained via symbiotic germination. Tree fern fiber, the ideal substrate for orchid seedling acclimatization, is increasingly scarce. Here, we evaluated seed germination and protocorm development of Cyrtopodium glutiniferum Raddi cultivated in asymbiotic media (Knudson C and Murashige & Skoog) and in oatmeal agar (OA) medium inoculated with the mycorrhizal fungus Epulorhiza sp., using non-inoculated OA medium as a control. We also evaluated the performance of tree fern fiber, pine bark, eucalyptus bark, corncob and sawdust as substrates for the acclimatization of symbiotically propagated plants. We determined germination percentages, protocorm development and growth indices at 35 and 70 days of cultivation. Relative growth rates and the effects of substrates on mycorrhizal formation were calculated after 165 days of cultivation. Germination efficiency and growth indices were best when inoculated OA medium was used. Corncob and pine bark showed the highest percentages of colonized system roots. The OA medium inoculated with Epulorhiza sp. shows potential for C. glutiniferum seedling production. Corncob and pine bark are promising substitutes for tree fern fiber as substrates for the acclimatization of orchid seedlings.