Polyploid induction by colchicine treatments and plant regeneration of Dendrobium chrysotoxum.

The purpose of this research was to investigate the effect of colchicines concentration and duration time to polyploid induction and plant regeneration of Dendrobium chrysotoxum L. The method was conducted by inclusion of colchicine into semi-solid VW medium. Protocorm like bodies (PLBs) of diploid D. chrysotoxum were treated with 0, 0.01, 0.02, 0.03, 0.04, and 0.05% colchicines (w/v) for 1, 2, 3, 4 and 5 days. The most effective treatment was 0.04% colchicine for 1 day which resulted in about 84% surviving PLBs and with 47 % of tetraploid orchids, as measured by flow cytometry. The treated PLBs were cultured on the same medium supplemented with 0, 0.5 and 1 mg L -1 NAA and 0, 0.5 and 1 mg L -1 BA for plant regeneration. Treated PLBs with 0.01% and 0.02% colchicines, the highest number of proliferated shoot (2.36 per explants and 2.44 per explant respectively) was obtained from 1 mg L -1 NAA and 0.5 mg L -1 BA. In the treatment with 0.03% and 0.04% colchicines, the highest number of proliferated shoot (3.40 per explants and 4.35 per explants respectively) was obtained from the culture media supplemented only with 0.5 mg L -1 BA and 1 mg L -1 BA .