Effects of Growth Regulators on Direct Flowering of Isolated Ginseng Buds <Emphasis Type="Italic">in vitro</Emphasis>

An in vitro method for obtaining gingseng inflorescences directly from explants of gingseng (Panax ginseng) is reported. Isolated shoot-buds of somatic embryo-derived plantlets ginseng were used as explants and incubated in B5 medium supplemented with 1 mg l⁻¹ benzyladenine (BA) and 1 mg l⁻¹ gibberellic acid (GA₃). About 15% of the buds flowered directly without developing vegetative organs. Cytokinin was found to be the key factor for inducing these isolated buds to proliferate and flower, but both these processes also occurred when benzyladenine (BA) was replaced by thidiazuron (TDZ). The optimal concentration of TDZ for obtaining the best ratios of bud proliferation and total flowering was 0.1 mg l⁻¹, while the highest number of vegetative shoots was obtained in medium supplemented with 1 mg l⁻¹ GA₃ and 0.1 mg l⁻¹ TDZ. The explant elongated abnormally in the presence of 10 mg l⁻¹ GA₃. Although a low concentration (1 mg l⁻¹) of NAA increased the bud proliferation ratio in the medium supplemented with 0.1 mg l⁻¹ TDZ and 1 mg l⁻¹ GA₃, a high concentration (5 mg l⁻¹) of NAA reduced the bud proliferation ratio and inhibited the flowering.