Especificidad del hongo micorrizico (Rhizoctonia sp.) en Phalaenopsis sp., Cymbidium sp., Trichoceros antenifer, Oncidium excavatum, y Cyrtochilum sp.

Abstract

Orchids produce abundant small seeds, lacking endosperm, cotyledons and reserve substances to support germination. That is why the seeds strategically establish a symbiotic relationship with a mycorrhizal fungus favoring germination and development. The aim of this study was to determine whether the mycorrhizal fungus Rhizoctonia sp. establishes a specific association with five orchid genera that stimulates seed germination. Two culture media were used: 1) PhytamaxTM and 2) oatmeal- agar+Rhizoctonia sp. The germination was assessed at day 45 and 75 and showed no specificity between the fungus Rhizoctonia sp. and Trichoceros antenifer, the orchid species from which the fungus was isolated. Germination in three of the five genera tested was higher in the treatment oatmeal agar+Rhizoctonia sp., showing in this treatment increased sizes and the development of vigor plants; although these data were not evaluated. The results also suggest that the host plant of the inoculated fungus could have an advantage in terms of time required for germination, but other species are also favored with the inoculum even if isolated from a different species.