The Study On Reducing Somaclone Browning Rate Of Butterfly Orchid

Butterfly orchid (Phalenopsis sp), with its high ornamental value and economic value, are popular inflower market both at home and abroad. Nowadays, butterfly orchid seedlings are multiplied mainly bytissue culture. However, during the tissue culture process of butterfly orchid, browning phenomenon arelikely to occur which seriously hindered the production of butterfly orchid seedlings on large-scale.To cutdown the happening rate of browning rate phenomenon in butterfly orchid somaclone production andincrease economic benefits of the enterprise, we used5popular cultivars ("Big pepper","Alishan girl"，"Red sky "，"Fire phoenix"，"Emperor") as materials, which introduced by Xi ’an Huishan EcologicalTechnology Co., LTD in recent years, to investigate the factors that affect browning occurring in theprocess of butterfly orchid tissue culture. The investigated factors include species and growth stage of theexplants, the length of inoculate explants, and disinfection reagent concentration and sterilization time, pHof cultivation medium, inorganic salt concentration light intensity and illumination time. The mainconclusions obtained in the trial are as follows.1. Browning rates of different genotypes were varied as the other culture conditions were same."Alishan Girl" had the highest of browning rate, next was “Big Pepper","Red sky" had the lowest. Thebrowning rate had been increasing with the cultivation time. Therefore, in order to decrease the browningrate of butterfly orchid in tissue culture process, we recommend “Red sky” as the best selection forbutterfly orchid tissue cultivation.2. The pedicel explants of "Big Pepper" at different growth periods were cultivated. The resultsshowed that the browning rate of pedicel which grown for30days was the lowest. The pedicel growing for45days was followed. The browning rate of pedicel growing for90days was the highest. The cuttingsection of pedicel explants to incubate with3cm in length appeared the lowest browning rate, compared toother length section including1cm,2cm,4cm,5cm,6cm,7cm,8cm,9cm. Considering other factors,the appropriate incubated explants of butterfly orchid pedicel should be3cm size and selected from pedicelwhich grow for about45days.3. The explants of "Big pepper" were disinfection with different concentration of HgCl2solution. Theresults showed browning rate was lowest when explants were treated with100mg/L HgCl2solution for12min. So the best disinfection for butterfly orchid should adopted100mg/L HgCl2solution for12min.4. For butterfly orchid tissue culture, the suitable pH value of culture medium was5.4to5.4, the most suitable concentration of iron ion is38mg/L, the suitable concentration of calcium salt ion is100mg/L,and potassium ion is1900mg/L.0.025mg/L is suitable concentration for both Cu ion and Zinc ion.5. The study also suggested the illumination conditions influenced on the tissue browning of butterflyorchid. The weaker of the cultivation light, the browning rate of “Big pepper” lighter. Browning rate ofbutterfly orchid of explants was lower when dark pretreatment for10days after inoculation than darkpretreatment for5days or15days. The shorter illumination time, the lighter of the tissue browning ratewas. Therefore, the suggested illumination condition to reducing browning rate of butterfly orchid duringtissue culture are keep low intensity light (200～500lx) for7to14days, or7working days to process dark,or gradually increasing light hours according to the2,4,6,8,10,12hours of gradient under1500-2000lxlighting condition. The most suitable temperature are from15to25℃at the early cultivation stager(7to14days), then raising to25to28℃.