Abstract: The immature embryos of Clivia miniata Regel.‘Shengli’were used as the explants to induce polyploid plants via colchicine treatment combined with tissue culture. The effects of colchicine concentration，treatment duration and embryo age on inducing polyploid plants were studied. The results showed that culturing 180 d immature embryos for 20 d on MS + NAA 2.0 mg · L-1 + BA 1.5 mg · L-1 containing 0.01% colchicine was the most effective treatment，with 30.8% tetraploid induction rate，36.5% morphological change rate and 34.1% death rate. The treatment was also excellent that culturing 120 d immature embryos for 30 d on the same medium containing 0.03% colchicine with the induction rate of tetraploid 24.0%，morphological change rate of 21.1% and death rate of 46.7%. Among 267 colchicine- inducing plantlets checked，30 were tetraploid（2n = 4x = 44），194 diploid（2n = 2x = 22）and 43 mixoploid. The average tetraploid-induced rate was 11.2%. In tube stage，the characteristics of slower growth，later and shorter roots，and wider and thicker leaves could be regarded as the available estimation indexes to the colchicine-induced tetraploid plants. 　　

Key words: Clivia miniata Regel., immature embryo, tetraploid, chromosome