Study On The Crucial Techniques In Vitro Culture And Polyploid Induction Of Cymbidium Grandiflorium

Cymbidium hybridium is a perennial herb of Orchidaceae,It is one of the most popularly cattleya in the word and a very important ornamental plant.The main propagation method of Cymbidium hybridium are seed propagation,division propagation and tissue Culture.In the study,the systemic tissue culture for Cymbidium Fortissimo 'Pianist' and Cymbidium Ruby Shower 'Murasakin Okimi' were studied.Based on the culture medium screening on best of all, we try to mouse out broad-spectrum culture medium which can let the explants bourgeon fine and let the PLBS develop consistently.The results of this experiment as follows:(1) The pretreatment of overshadowing before inoculation and deal with low temperature after inoculation all can reduce the browning of explants;The culture medium and the dosage of 6-BA are key factor of PLBS induction,The optimal medium of PLBS induction is KC+6-BA 1.0mg/L+NAA0.05mg/L+AC2mg/L,When the inducing rates of explants were 53.3%.(2) In the study of PLBS synchronization of development,the density of explants effected the multiplication and differentiation very observably,in the medium. 1/2MS+6-BA1.0mg/L+NAA0.2mg/L+AC1.0g/L,when the density of explants was 8/cm2,the differentiation rates were 60.35%.(3) It was the most effectively induced by immersing PLBS in 3%colchicines solution for 48 hours, its inductive frequency was 23.3%,there were high rates of death and badly hurt of PLBS with the exorbitant consistence of colchicines and long time immersion.(4) When adding colchicines in medium after 40 days in 1%colchicines or 30 days in 3%colchicines, the effect of PLBS inductive frequency were 27.8%and 30.0%.(5) When adding colchicines in medium for clumpy buds,colchicines toxicity to clumpy buds was larger,the rate of death was higher,after 40 days in 5%colchicines the death rate reached 84.44%;after 40 days in 3%colchicines,the highest mutagenic rate reached 15.56%.(6) Plant polyploidy was analyzed by preparation section and then chromosome numbers of the root tips were observed under a microscope,It showed that the tetraploid contained 48 chromosomes,twice the normal diploid number of 40.Compared with the diploid,the tetraploid leaves showed bigger,darker and thicker:the guard cells and stomas showed bigger with lower density:the contents of chlorophyll showed more than diploid plants.