Screening Of Mycorrhizal Fungi And Structure Study Of Mycorrhiza Of Several Endangered Wild Orchids In Yunnan Province

Abstract: Orchids is refer to the species in Orchidaceae family. Chinese orchid is cl(?)ssified as genus Cymbidium in Chinese traditional concept. In most cases, people refer Chinese orchid to terrestrial orchids in genus Cymbidium in orchidaceae family. The orchids have high valve in ornament and economy and they are very diverse and widely distributed in Yunnan province. At present, development and utilization of orchids resource are in a primary stage. Because demand of orchids is much higher than its supply, the farmers driven by economic benefit started to excavate wild terrestrial orchids on the mountain. The natural resources of terrestrial of orchids were destroyed seriously. If the method of large quantity propagation of orchid is not developed, protection of terrestrial of orchids will be kept in talking. Currently, the tissue culture was used. But the tissue culture plantlets have very low survival rate after transplanting, growth slowly, delayed blossom or no blossom without mycorrhization. It was found that Endophytic fungi of orchid can provide more nutrients, hence promote growth and development through mycorrhization. Therefore, mycorrhization in tissue culture is a useful technique for the large quantity propagation of endangerous Orchids.To understand the relationship between orchids and endophytic fungus, fungi strains from natural roots of orchids were isolated and inoculated into the roots of [Cymbidium goeringii (Rchb.f.) Rchb.f.], C .hookerianum and Dendrobium devonianum (growing in moss mix in with vermiculite) and Cymbidium goeringii under tissue culture and soil culture condition. Through inoculation under tissue culture condition, some good strains that can promote the growth of orchids significantly were screened. By using indicators such as fresh weight increment of growth, micro- and ultra-micro-structure of cortical cell of the roots, re-isolation and inoculation, etc, it is confirmed that a symbiosis culture system for Rhizoctonia sp. and orchids was established. By the observation under electronic microscopy, the process that the hyphae was dissolved and absorbed by orchids root and other changes in ultra-micro structure were observed. The research is aimed to establish a method for propagation of orchids plantlet by tissue culture with inoculation of endophytic fungi. We believe this method maybe useful for propagation of other rare orchid species. The detail results are shown as follows:1. The seeds of Cymbidium goeringii, C. hookerianum, Dendronbium devonianum can be induced to germinate and form seedlings on culture media. Adding some coconut milk...