Propagation of Polygonatum macranthum (Maxim.) Koidz. from immature seeds using a new sterilization procedure

Natural seed germination is difficult to achieve in numerous plant species of wide economic importance. The germination of Polygonatum macranthum seeds takes as long as one and a half years under natural conditions. In addition, propagation by rhizome is also extremely slow in this species. Therefore, the natural propagation of P. macranthum through seeds or rhizome is not efficient. In this study, an efficient in vitro propagation system for P. macranthum from immature seeds with seed coat was developed, using a new surface sterilization protocol that utilized a low concentration of hypochlorite. In vitro germination was achieved at a rate of 30% within 9 weeks after inoculation on 1/2 MS medium. Shoot explants from seedlings were successfully cultured on 1/2 MS medium. Supplementation of the 1/2 MS medium with cytokinin 6-benzylaminopurine (BAP) facilitated efficient propagation by microrhizome. An efficient propagation rate of 1.3 microrhizomes per shoot in an 8-week culture period could be achieved by using a concentration of 1 mg l^-1 BAP. During 4 weeks of acclimatization, 88% of shoots were rooted and started to grow into juvenile plants. After about 16 weeks in the field, 13% of the acclimatized plants showed viable growth and healthy regenerating shoots. The cultivation system demonstrated in this study can be used to propagate P. macranthum.