The Optimization Of The Tissue Culture Technology Of Dendrobium Candidum

Dendrobium candidum Kimura et Migo also named Hei jie cao or Tie pi Ian, refers to a types of orchid dendrobium perennial epiphytes. It is the nonesuch in dendrobium plants for its unique medicinal value. And now people had got its tissue culture seedling successfully by the tissue culture technique; however, there are still many problems on the tissue culture of D.caudidum,such as:etiolating of tissue culture,variation of tissue culture and the low survival rate. In this paper, by orthogonal experimental design, the optimization study has been done for the condition of tissue culture in D.caudidum using the ripe fruit and stem of D.caudidum as materials. The main results obtained from the experiment as follows:(1) The optimal embryo germination medium:MS or 1/2MS+6-BA1.0mg/L+ NAA1.0 mg/L+coconut juice 100ml/L+Active carbon 1.0g/L+Sugar 25g/L+Agar 4.6g/L,and the embryo germination of D.caudidum could germinate early by adding hormone and coconut juice to the medium,.(2) The optimal explants sterilization method:the explants was still unpolluted after 30 days cultivation, because it was disinfected with 75% ethanol to 30s,after brushing under tap water 30 min then treated with 10% NaCIO for 8min+0.1% HgCl2 for 5min+0.2% HgCl2 for 2min.(3) The optimal auxiliary bud induction medium:MS+NAA0.8mg/L +6-BA1.0mg/L+Sugar 25g/L+Agar 4.6g/L, stem induction rate reached 85%.(4)The optimal cluster buds induction medium:MS+NAA0.5mg/L+ 6-BA1.0mg/L+KT2.0mg/L+Sugar 25g/L+Agar 4.6g/L, the number of cluster buds was the largest, the aberration rate was not high, and the tissue culture seedling grew very strong with green leaves.(5) The optimal multiplication medium:1/2MS+NAA1.0mg/L+6-BA 0.2mg/L+ KT 0.2mg/L+Active carbon 0.5 g/L+5%potato juice+Sugar 25g/L+Agar 4.6g/L, the multiplication coefficient reached 8.3,the protocorm grew compact with green,and they had no variation and browning.(6) The optimal differentiation medium:N6+6-BA0.5mg/L+KT1.0mg/L+ potato juice 100g/L+Active carbon 0.5 g/L+Sugar 25g/L+Agar 4.6g/L, the differentiation rate reached 87.7%L, the number of adventitious bud was large, the adventitious bud grew strongly and regularly with green leaves.(7) The optimal strong seedling induction medium:N6+6-BA0.5mg/L+ NAA1.0 mg/L+banana juice 150g/L+Active carbon 0.5 g/L+Sugar 25g/L+Agar 4.6g/L, the result showed the comprehensive score of 4 evaluation index was the highest in No.8 treatment, including shoots、fresh weigh、plant height and stem diameter, and its score reached 34.796.(8) The optimal rooting induction medium:MS+NAA2.0mg/L +Active carborn1.0 g/L +banana juice 150g/L+Sugar 25g/L+Agar 4.6g/L, its tissue culture seedling grew very strong, the root was not only with much number but stout, average root length reached 3.5cm and average root number reached 6.3. The survival rate of tissue culure seedling transplanting was high,and it reached more than 95%.