Optimization of highly efficient plant regeneration system for Lilium davidii var. Unicolor (Hoog) Cotton.

[Objective]The present experiment was conducted to optimize tissue culture conditions for Lilium davidii var. Unicolor (Hoog) Cotton, to improve plantlet regeneration rate and to establish high efficient plant regeneration system from scales. [Method]Scales of L. davidii were used as explants for the induction, multiplication and rooting of bulbs in basic MS medium containing different combinations and concentrations of NAA(0.2-1.0 mg/L), 6-BA(0.5-2.0 mg/L), KT(0.1-1.0 mg/L), IBA(0.2-1.0 mg/L) and IAA(0.2-1.0 mg/L). [Result]The rate of induction and average number of induced bulbs was higher in the medium containing 1.0 mg/L 6-BA and 0.2-1.0 mg/L NAA. The average number of induced bulbs increased with increasing concentration of NAA in medium and reached the highest (5.9) in the medium containing 1.0 mg/L 6-BA+1.0 mg/L NAA. Compared to combination of 0.5-1.0 mg/L KT+0.2 NAA mg/L in medium, the combination of 0.5-1.5 mg/L 6-BA+0.5-1.0 mg/L KT or 0.2 mg/L NAA was more beneficial to the multiplication of bulbs, but the multiplied cluster buds of bulb showed weak growth, however, the cluster buds grew well in the medium containing 0.5 mg/L 6-BA+0.2 mg/L NAA. Supplementing 0.2-1.0 mg/L IAA or IBA in MS and 1/2MS medium, respectively, the rooting rate in bulbs and quality of root decreased with increase in IAA or IBA concentration, however, the average number of roots and root length showed different trends. The quality of root was better in 1/2MS medium supplemented with IBA than that in MS medium with IAA. [Conclusion]The MS medium containing 1.0 mg/L 6-BA + 0.5-1.0 mg/L NAA was the best for induction of bulbs, MS medium containing 0.5 mg/L 6-BA + 0.2 mg/ L NAA for bud multiplication and 1/ 2 MS+0.2 mg/L IBA for the rooting which resulted in fine growth of roots with 100.0% rooting rate.