Abstract: The shoots of Cymbidium hybridium were soaked in colchicine solutions at different concentrations and treatment times to induce doubling of body cell chromosome. Ploidy levels were identified by morphological and cytological traits. The results showed that the treated shoots of C.hybridium with 0.05% colchicine for 24 h had a higher inducing rate which was up to 28.2%. The external morphology, the number of chloroplast as well as the number and size of stomata were obviously different between the diploid and polyploid. The nucleus of polyploid cell was obviously bigger and the number of chromosome was increased.

Key words: Cymbidium hybridium, colchicine, chemical induction, polyploid