Objective and methods: To study the effect of rare earth
elements on cell and tissue cultures of the medicinal plants. Using
Coptis chinensis as plant material, the effect of the rare earth
elements Yb 3+ and Eu 3+ at various
concentrations on the callus growth were investigated. The calli, induced from explants in Coptis chinens , were inoculated on 67 V media containing various concentration of Yb 3+ and Eu 3+ . After a period of culture, calli were weighed precisely. We studied the effect of Yb 3+ and Eu 3+ at various concentrations on the callus growth and the continuing growth of calli transferred on the medium free of rare earth elements. Results: 0.1 mg·L -1 Yb 3+ and 1 mg·L -1 Eu 3+ stimulated the callus growth, but higher concentrations inhibited the growth. The callus increment of fresh weight was lower than the control when the calli, derived from the media containing various concentrations of Yb 3+ and Eu 3+ , were transferred and cultured on the medium free of rare earth. Conclusion: The callus growth was stimulated by the lower concentration of rare earth elements. The lower and higher concentration of Yb 3+ and Eu 3+ was deleterious to the continuing growth of the calli transferred on the medium free of rare earth.