The Influences Of Co-cultivation With Pinus Massoniana Or Castanopsis Fissa On The Symbiotic Establishment Of Cymbidium Hybridum

As an important plant resource, the orchidaceae has economic and scientific vaule. It is well known that the development of orchidaceae in nature depends particularly on mycorrhizal fungi. And several chlorophyllous species in orchidaceae also associate with mycorrhizal fungi in adult. So this implies that mycorrhizal fungi play an important role in orchid conservation and culture.In this study, Cymbidium hybridum plantlets were used as the plant material. The effects of microenvironment of root system of two woody species, Pinus massoniana,Castanopsis fissa, on Cymbidium hybridum vegetative growth were explored.At the same time, the relationship of rhizosphere fungi between the woody plants and Cymbidium hybridum was studied by methods such as mycorrhizal staining, fungal isolation, ITS sequence identification, confrontation culture. The main results were summarized as the following:1. The data of physiological index of Cymbidium under Pinus were significantly lager than those under Castanopsis fissa after 5 months. And, Cymbidium plantlets under Pinus massoniana which were applied with 3A-3 and special ecto-mycorrhizal agents grew best among all experimental groups. Fresh weight, plant height, root number, root length, dry weight of all aspects of indicators had a great improvement.2. Growing together with Pinus massoniana and Castanopsis fissa could significantly promoted the absorption of mineral elements P and Fe to Cymbidium.3. Co-cultured five months later, determination of 5 groups of Cymbidium Hybridum in 13 C and 15 N content were significantly higher than Pinus massoniana, Castanopsis fissa,Schefflera arboricola, Dryopteris tenuicula, showed that Cymbidium absorbed the 13 C and15N nutrients from the soil through the fungi. It indicated that Cymbidium and the fungi formed a good symbiotic relationship.4. Root segments of Cymbidium hybridum potted in Greenhouse in 5 months were plant materials. Root segments containing hyphae were selected under the microscope. The best isolation conditions were: using 75% alcohol to clean the root surface 30 s, then disinfected by 2% sodium hypochlorite solution for 30 min, removed the root layer, putting on the PDA which added antibiotic of streptomycin and tetracycline hydrochloride.5. The fungi isolated from the root of the three kinds of plants were identified by molecular identification. The main fungi in the root of Pinus massoniana belong to:Ascomycetes sp., basidiomycetes sp., Sordariomycetes sp., Tulasnella sp., Fusarium sp..That of Castanopsis fissa belong to Umbellopsis sp., Mortierella sp., Fusarium sp.. That of Cymbidium hybridum belong to Ascomycetes sp., Tulasnella sp., Epulorhiza sp., Fusarium sp., Trichoderma sp., Aureobasidium sp., Mortierella sp., Sebacina sp.6. The fungi isolated from the root of Pinus massoniana were put in DE culture medium with Cymbidium for 20 days. There were some fungi adherend on Cymbidium root,but did not invade into cortical cells.7. Confrontation culture for the isolated fungi and the common orchid pathogenic fungus Fusarium R was conducted. The inhibitory rates of L3, L4, H3-1, H3-2 and H3-3 on R were 46.22%, 35.02%, 38.82%, 31.60% and 33.18%, respectively, which effectively inhibited the growth of Fusarium.