Under aseptic conditions, hypocotyls of mulberry were averagely cut into 3 segments which were then cultured on MS solid medium supplemented with 3.0 mg5L -1 6-BA, 0.3 mg5L -1 IAA, 1.0 mg5L -1 AgNO3 to select the best region of hypocotyls for getting the more caesptose shoots. In this study, the tip part of hypocotyls（near the germ） developed quickly and induced adventitious buds easily. The caesptose shoots were dipped into 1,1.5, 2.5 g5L -1 colchicines solution for 2 or 3 days, or dropped with 1.5, 2, 2.5 g5L -1 colchicines solution 2 times a day for 5 days, and then transferred to fresh medium. Both the dipped-and dropped-treatments induced variant shoots. Examination of the chromosomes of the shoot tip cells of the regenerated plantlets revealed that they were either tetraploids or chineras. The rate of tetraploids produced from the dipped-and dropped-treatments was 14% and 20% respectively with the chromosomes number of 56（2n=4x=56） as compared to the diploid（2n=2x=28）.
