Micropropagation and bulblet transplantation of Lilium cernuum

Lilium cernuum is a national key resource of protected wild plants in China. To propagate and produce this wild lily commercially, we have conducted tissue culture and bulblet micropropagation, enlargement, and transplantation. We used bulb scales and shoots as explants to establish micropropagation systems. The germination rate of the inner scales was lower than that of the outer scales, which was again lower than that of the middle scales. The optimal medium for adventitious bud differentiation from bulb scales and axillary buds from shoot segments was MS + 6-BA 0.5 mg L^‑1 + NAA 0.2 mg L^-1, and the optimal medium for proliferation of adventitious and axillary buds was MS + 6-BA 0.5 mg L^-1 + NAA 0.1 mg L^-1, with a proliferation coefficient up to 2.03 and 0.92, respectively. Tests showed that paclobutrazol (PP₃₃₃) is the major factor affecting the enlargement of bulblets. The optimum concentration of PP₃₃₃ was 30 mg L^-1. So far, we have obtained more than 1500 in vitro bulblets of six populations. We transplanted bulblets of circumference around 3.5 cm after 2 days' hardening. Those potted in nutrient medium and grown in the solar greenhouse with daily management survived better than those planted in wild fields. The bulblets planted in Beijing sprouted continuously with high germination rate over 3 years, and blossomed in July 2015. This research provides an effective pathway for large-scale micropropagation of L. cernuum.