An Efficient In Vitro Culture System for Pteris nipponica W.C.Shieh

Abstract

Pteris nipponica W.C.Shieh, an evergreen perennial fern with high ornamental value, is an endangered and ecologically important plant in Korea. This study was conducted to optimize the culture conditions for spore germination, sporophyte formation, and subsequent growth, thereby establishing an efficient mass propagation system for P. nipponica. To investigate the effect of ammonium nitrate (NH4NO3) on sporophyte formation and growth, prothalli were cultured for 6 weeks on half-strength MS basal medium containing different concentrations of NH4NO3. The M-3 medium, containing half the standard concentration of NH4NO3, achieved the highest sporophyte formation rate of 58.8%, significantly surpassing M-1 (27.5%) and M-2 (23.8%). Statistical analysis revealed that the concentration of NH4NO3 had a significant effect on sporophyte formation (p=0.0039). Furthermore, the M-3 medium significantly promoted sporophyte growth indicators such as root number, root length, shoot length, and shoot width compared to the M-1 and M-2 media. Therefore, the optimal nitrogen source for effective sporophyte formation and development in P. nipponica was identified as a half concentration of NH4NO3 (5.15 mM) in medium. The formed young sporophytes were transplanted into trays containing sphagnum moss for 4 weeks of acclimatization before being moved to a greenhouse. After 12 weeks, a high survival rate of over 95% was observed. The culture conditions and acclimatization methods established in this study are expected to be practically applicable to the efficient mass production of P. nipponica and various other fern species.