Effect of Plug Tray Cell Numbers, Nursery Periods and Transplanting Times on the Seedling Quality and Rhizome Yields of Cynanchum wilfordii Radix

Background: Seed propagation has become the most popular method for rhizome production in Cynanchum wilfordii Radix. However, no systematic seed propagation systems have been established. This study was conducted to determine the effect of plug-tray cell number and nursery period on the seedling quality and rhizome yield of C. wilfordii and evaluate the suitability of trans- planting time.BR/Methods and Results: Seeds were sown from March 8 to April 21, 2022, at 15-day intervals, and the seedlings were grown in trays with varying cell numbers (50, 72, 105, and 128 cells) for 30, 40, or 50 days in a glass greenhouse. Seedlings grown in trays containing 105 cells for 40 days were transplanted from April 17 to June 1, 2023, at 14-day intervals. The results of the first experiment showed that the seedling quality of C. wilfordii improved with increasing cell volume of the plugtray and with increasing nursery period. Overall, good seedlings were obtained when grown in trays of 50 cells for at least 40 days. The highest rhizome yield occurred in the 105-cell treatment when the seedlings were grown for 40 days or more. Regarding the effect of transplanting time on rhizome yield, the yield increased with advancing transplanting time. For example, fresh rhizome weight was approximately 95 g at the earliest time of transplanting on April 17, estimated at 309 ㎏․10asup-1/sup.BR/Conclusions: Seedling quality and rhizome yield improved with larger tray cells and longer nursery periods. The highest yield was achieved with seedlings grown in 105 cell trays for 40 days and transplanted in mid-April in the area of Chungcheongnam-Do.