Evaluación de un medio óptimo para el crecimiento in vitro y ex vitro de orquídeas del género Epidendrum micorrizadas

Abstract

The fungus-orchid symbiosis (mycorrhiza) is the interaction between the hyphae of a fungus species and the roots of a plant, forming a structure through which exchange of water, nutrients and growth regulators take place. This symbiosis has allowed orchids to grow and adapt to different types of habitats. In the present study, seedlings of Epidendrum sp. mycorrhizae with two fungi, Sebacina vermífera and Ceratobasidium sp., were used to study the in vitro and ex vitro growth of orchids, using three different culture medium. The study was carried out in the Orchid garden of the Chemical Sciences Faculty of the University of Cuenca and seedlings from the project "Study of the symbiotic relationship of orchid-mycorrhiza in the Province of Azuay, Ecuador" (DIUC XIV-16)” were used. The Murashige & Skoog Modified banana medium (Modified MS) and Oat Meal Agar (OMA) medium were prepared for the in vitro culture; and substrate (fine pine bark, Sphagnum moss and limestone) for the ex vitro culture. The viability and growth of the orchid were evaluated in the three culture medium, with the two types of mycorrhizal fungi. The results showed that the medium that allowed an optimal viability is Oat Meal Agar (OMA) for mycorrhizal seedlings with Sebacina vermífera (86%) and with Ceratobasidium sp. (73%). On the contrary, the medium with the lowest percentage of viability for Sebacina vermífera was substrate with 59% and for Ceratobasidium sp. was the MS Modified banana medium with 22%. The in vitro growth was higher than the ex vitro growth, being the Murashige and Skoog Modified banana mediumthe one that presented the lower growth, but greater homogeneity of the seedlings. The Oat Meal Agar (OMA) medium was the biggest growth for the seedlingswith the two symbiotic fungi.