Research On Tissue Culture And Cold Resistance Of Dendrobium Officinale Collected From Three Regions

Dendrobium officinale (Kimura et Migo) as traditional medicinal plant belongs to Orchidaceae, it needs about five months from pollination to fruit maturity. Under natural conditions seeds need to be symbiotic with the fungus to germinate, so the germination rate is very low. All those reasons lead to very low reproductive rate. Very low reproductive rate and long-term uncontrolled excavation made the resources of wild Dendrobium officinale gradual depletion. The effective way to solve the market demands problem of Dendrobium officinale is to expand the planting area and planting region. Seed sources, particularly the screening of high-quality seedlings become the key problems to be solved. The most effective way is to develop artificial rapid propagation of good seed plant by tissue culture techniques.In this study, the Dendrobium stem segments of three different origin were used as explants, and the rapid propagation system have been established. All media used in this work contain2.5%sucrose and0.78%agar with pH value of5.8. Then the seedlings obtained by tissue culture were used to study the physiological changes after low-temperature stress treatment to screen out the kind with good cold hardiness and to achieve the scale cultivation and planting geographical expansion of Dendrobium officinale. The results are as follows:The propagation system of three kinds Dendrobium officinale are established.1. The best surface disinfectants and disinfection time. The disinfection effect of the three Dendrobium officinale stem section with commonly used surface disinfectants0.15%mercuric chloride and5.0%sodium hypochlorite solution were compared, the results show that0.15%mercuric chloride solution for8minutes on three Dendrobium officinale stem segments has the best disinfection effect with lower polluted and higher germination rate.2. A variety of media were used to induce three Dendrobium officinale stem segments, the results indicate that the medium N6+BA2.0mg/L+NAA1.0mg/L+10%banana juice+10%o activated carbon are suitable for the induction of three three Dendrobium officinale compared with other media.3. A variety of media have been tested to screened out the optimal medium for proliferation and differentiation at this stage, the best medium is N6+6-BA2.0mg/L+NAA1.0mg/L+10%banana juice.4. Rooting test on a variety of media filtered out the best rooting stage medium is N6+ NAA0.5mg/L+10%banana juice.5. Transplant and domestication:A variety of commonly used tissue culture transplanted matrix have been used to screen for the appropriate transplanting medium. The result is gravel:sawdust=1:1; the right culture transplanting season is from May to June.The determination of cold physiological indicators and cold-resistant seed screening. In this study, low temperature stress on tissue culture of three different origin of Dendrobium officinale were setted to determine the physiological indicators, including the membrane conductivity, the polysaccharide content in the leaf tissue, changes in free proline content, malondialdehyde content and other physiological indicators. According to the results there are significant differences in the strength of resistance to the cold is the Henan Xixia> Hunan Langshan> Yunnan Wenshan.