Study On Liquid Suspension Culture And Artificial Seeds Technology Of Dendrobium Candicum Wall. Ex Lindl.

Dendrobium candicum Wall. ex Lindl. is a perennial epiphytic herb belongs to Orchidaceae and is a extremely precious medicinal plant. Because the natural propagation coefficient is low, in addition long-term uncontrolled excavation, the wild resources of Dendrobium candicum gradual depletion. Reproductive rate is also low by traditional modes of reproduction such as division and cuttage. Tissue culture could obtain a large number of seedlings, but there are some problems still exist, for example, high-frequency subculture, long production cycle, high cost and low survival percentage of transplant.We added different concentration of active carbon, sodium thiosulfate and polyvinyl pyrrolidone in liquid medium, to study their effect on propagation, browning and differentiation of Dendrobium candicum protocorm; then encapsulate protocorm by sodium alginate and calcium nitrate to produce artificial seed, to study the effect on artificial seed germination by adding different artificial seed coat, basic culture medium, carbon source, carbendazol and active carbon in artificial endosperm and effect on artificial seed storage by adding abscisic acid.1. Adding active carbon could increase the reproduction rate of Dendrobium candicum protocorm significantly and alleviate browning effectively, but the protocorm differentiated seriously; adding sodium thiosulfate could alleviate browning effectively, but the reproduction rate of protocorm is reduced; adding polyvinyl pyrrolidone could increase the reproduction rate significantly and alleviate browning effectively, it’s suitable as additive in fluid suspension culture of Dendrobium candicum protocorm,0.05g/L is the best concentration, while protocorm reproduction rate is120.7%and browning rate is25.9%.2. Dendrobium candicum artificial seed encapsulated with2%sodium alginate was low hardness, easy to adherent, nutrition substance leaked out seriously, although its germination rate was high; artificial seed encapsulated with4%sodium alginate was high hardness, ragged edges, caudiferous and low germination rate, although nutrition substance leaked out lightly; artificial seed encapsulated with3%sodium alginate and50 mmol/L calcium nitrate was low hardness, nutrition substance leaked out seriously; artificial seed encapsulated with3%sodium alginate and100or150mmol/L calcium nitrate was regular and uniform in shape, both nutrition leakage rate and germination rate were at a better level, in which3%sodium alginate and100mmol/L calcium nitrate complexing25min was the best condition to produce Dendrobium candicum artificial seed.3. Adding MS as basic culture medium in artificial seed obtained the highest germination rate, but there is no distinct difference among MS,1/2MS and1/4MS as basic culture medium.4. Germination rate was the highest when maltose as carbon source of artificial seed, the effect of sucrose, fructose and glucose were similar to maltose, lactose as carbon source the germination rate was obviously lower than the before mentioned four kinds of carbon source, tragantine was the worst carbon source because its germination rate was only a little higher than blank control.3%was the best in different concentrations of sucrose, both low and high concentration sucrose were not propitious for germination of artificial seed.5. Low concentration of carbendazol cannot control the growth of microbe effectively, artificial seed contamination rate was high and germination rate was low; high concentration of carbendazol could control the growth of microbe effectively, there is no contamination in artificial seed, but carbendazol was toxic to plant material, so the germination rate was also low;0.3%and0.4%carbendazol could control contamination rate and fatality rate at a lower level, so the germination rate by them were higher than others, their germination rate were86%and87%.6. Artificial seed adding high concentration active carbon germinated slowly and germination rate was low, adding low concentration of active carbon could increase the germination rate of artificial seed, in which germination rate was99%when active carbon concentration was0.2%.7. Adding20mg/L abscisic acid in artificial seed of Dendrobium candicum, the germination rate was still45%after storing6months in4℃refrigerator, while the artificial seed without abscisic acid hadn’t germinated.