Stimulation of In Vitro Bulblet Growth by the Addition of Liquid Medium in Lilium Oriental Hybrid 'Casablanca'

The bulb scales and shoot sections ($7\;\cal{mm}\;\times\;15\;\cal{mm}$) of Lilium oriental hybrid 'Casablanca' were cultured to compare bulblet growth in vitro. Shoots were induced from in vitro grown bulbscales on MS medium with $1.0\;\cal{mg/L}\;BA,\;0.5\;\cal{mg/L}$ IAA, and 30 g/L sucrose. The regenerated shoots were cut into shoot sections, and cultured on MS medium with $2.0\;\cal{mg/L}\;BA,\;0.5\;\cal{mg/L}$ IAA and 30 g/L sucrose for shoot proliferation. Culture of shoot sections stimulated bulblet growth significantly than the bulb scales on MS medium with 60 g/L sucrose. However, the bulblets from shoot sections did not reach ideal size to produce stems with several leaves. Therefore, liquid medium was added into the same vessels to stimulate bulblet growth further. After shoot sections were cultured on MS medium with 60 g/L sucrose and 2 g/L activated charcoal for two months in dark, $20\;\cal{ml}$ liquid media containing various concentrations of sucrose and MS salts were added. Two months later, the added liquid medium stimulated bulblet growth remarkably as compared to bulblets grown without added liquid medium. The added $25\;\cal{ml}$ liquid medium containing 120 g/L sucrose and double strength of MS salts were the most effective for growth of in vitro bulblets. More than $94\%$ bulblets produced by this method sprouted stems with several leaves after cold treatment at $5^{\circ}C$ for three months.