Abstract
Flower bud formation in shoot apex cultures was investigated using vegetative buds from the leafing and dormant stages in Gentiana triflora Pall. var. japonica Hara and Gentiana scabra Bunge var. buergeri Maxim. A few plantlets had flower buds 105 days after starting the in vitro culture. When buds from the dormant stage were used for the culture, 6 % or less of the plantlets had flower buds in all lines. After 165 days, more than 50 % of plantlets from buds from the leafing stage had flower buds, while flower bud formation was lower in plantlets from buds at the dormant stage. There were no flower buds found on plantlets from buds at the dormant stage during the culture period in Gentiana scabra.
The effects of flower buds and of plant growth regulators on shoot formation were examined using in vitro node culture. The growth of shoots at the upper nodes from plantlets with flower buds was poorer than that from plantlets without flower buds. By contrast, shoots at the lower nodes from plantlets with flower buds were rather long. In culture medium containing forchlorfenuron and naphthalene acetic acid (NAA), many shoots formed from the nodal segments of plantlets without flower buds. Plant growth regulators also enhanced shoot formation from the nodal segments of plantlets with flower buds. The lengths of the shoots were similar between plantlets with and without flower buds. These results suggest that plantlets with flower buds are still useful for node culture, especially with the addition of forchlorfenuron and NAA.
