dc.description.abstract | Teak (Tectona grandis L.) is one of the forestry plants that have a high economic value and an important role in carbon absorbing. Chromosome doubling in teak was intended to produce a better plant both morphologically and it’s wood quality. Antimicrotubule, such as oryzalin treatment is one of the chromosome doubling inducing method. This research was conducted to get the most effective concentration and treatment period to induce the chromosome doubling of teak through in vitro culture. It’s effectivity was measured by the changes of chloroplast number in the stomatal guard cell and stomatal density, also supported by the lowest lethal effect that was measured by it’s survival percentation. The most effective oryzalin treatment to induce chromosome doubling of teak from diploids into tetraploids was estimated at 5 μM concentration with 3 days treatment period. The survival at this treatment reached 70% of the treated plants. In which about 60% of the treated plants had a doubled chloroplast number in their guard cells from average 6,0-11,9 into 12,0-23,9 chloroplast per stoma along with the decreased of stomatal density. | en |