Improvement of in vitro micropropagation of Lilium oriental hybrid 'Casablanca' by the formation of shoots with abnormally swollen basal plates

Bulb scales of Lilium oriental hybrid 'Casablanca' were cultured on MS medium supplemented with cytokinins (kinetin, BA (benzyladenine), TDZ (thidiazuron)). The basal part of bulb scales swelled and formed adventitious shoots with foliage small, leafy bulb scales and abnormally swollen basal plates on the media with cytokinins. Shoots were formed rapidly from the basal parts of bulb scales and became shoot clusters. The medium containing 2.2 μM BA was most favorable in the shoot formation from bulb scales. Cutting shoots into small segments (7-8 mm wide × 12-15 mm length) were cultured on media containing BA and IAA (indole acetic acid) and the segments regenerated many new shoots and formed shoot clusters. The shoot section to shoot cluster cycle method improved adventitious shoot proliferation. The media supplemented with 4.4 μM BA and 5.7 μM IAA. or 8.9 μM BA and 0.6-2.9 μM IAA were effective in allowing the proliferation of shoots from shoot segments under light condition. Sucrose and activated charcoal (AC) improved bulblet growth. Bulblet growth was effectively performed on MS medium containing 60 g/L sucrose. Bulblet growth was also improved by the supplement of AC. The medium with 2.0 g/L AC was most effective for bulblet growth. Normal bulblet growth was stimulated more by the culture of shoots than that of bulb scales. Bulblet weight from shoots reached to an average of over 1100 mg of a bulblet after 3 months in culture on MS medium containing 60 g/L sucrose and 2 g/L AC. Most of the bulblets produced by this method generated stems with several leaves in the green house, after cold treatment at 5 °C for 3 months.