In Vitro Propagation and Post-in Vitro Establishment of Bulblets of Lilium japonicum Thunb.

Lilium japonicum growing in the experimental field were collected in early May and segments of their scales, leaves and stems of the plants were cultured in vitro on a basal medium consisting of Murashige and Skoog's inorganic salts (1962) supplemented with several organic nutrients. Young leaf-segments were a suitable source for propagation, because they were least contaminated and almost had the same capacity as scale seg- ments for bulblet regeneration. Bulblets were proliferated by culturing whole scales or segments on the basal medium supplemented with 0.1 mg•lliter-1 NAA and 0.01 mg•lliter-1 BA. A cold treatment at 4 °C for more than 12 weeks broke the dormancy of in vitro cultured bulblets. In vitro light conditoin affected both post-in vitro bulblet-rot infection and plant growth in soil. The bulblets incubated in the dark were more sus- ceptible to soil-born organisms than were those incubated in the light. Nearly all the bulblets of more than 400 mg in weight grew into plants with elongated axes (epigeous type plant; ETP). The ETP plantlets required at least 2 years' cultivation before they flowered.