This study was conducted to develop a seed propagation protocol of Hemerocallis taxa native to the Korean Peninsula. In this study, the seed dormancy types were classified. The germination traits of H. thunbergii, H. dumortieri, H. hakuunensis, and H. hongdoensis were also characterized. The initial embryo to seed length ratio (E:S ratio) in seeds of the four Hemerocallis species was between 0.80 and 0.90 at harvest, however, the E:S ratio did not increase until just before germination. Thus, seeds of the four Hemerocallis species had no morphological dormancy (MD), and at least 84% of seeds of all tested species germinated at 25/15℃ under light within 30 days. The lower the incubation temperature, the lower the germination rate of seeds of the four Hemerocallis species. However, the temperature range for germination was expanded due to old stratification. Gibberellin treatment increased the germination rate or germination speed at a relatively low temperature of 15/6℃. However, this treatment did not improve the germination rate as much as the temperature at 25/15℃. Under 15/5℃ of incubation, cold stratification increased the final germination percentage and rate/speed and expanded the temperature range for germination from high to low (25/15℃ → 15/6℃). This indicates that the seeds have a conditional dormancy (CD) that germinates in a narrow temperature range. In conclusions, the four Hemerocallis seeds exhibited nondeep physiological dormancy.

Tiarella polyphylla D. Don is a native plant distributed only in Ulleung Island in Korea and has been traditionally used for medicinal purposes, although it is also used ornamentally. This study was conducted to determine the requirements for dormancy break and germination and to classify the type of seed dormancy. The experiments were performed with cold stratification (0 or 12 weeks at 5℃), warm stratification (0, 4, 8, or 12 weeks at 23℃, followed by 8 weeks at 5℃, and then incubation at 23℃), and GA3 treatments (0, 10, 100, or 1000 ㎎/L). The treated seeds were incubated on aseptic media at room chamber (23℃, a 16h photoperiod of fluorescent lamps with 40 μmol ․ m-2 ․ s-1). The seeds were dispersed in nature as underdeveloped embryos with no physical barrier to absorb water to prevent water absorption. However, the seeds did not germinate for 30 days after sowing without any pre-treatments. Thus, the seeds had morphological dormancy (MD) and physiological dormancy (PD). The final germination percentage following cold stratification (0 or 12 weeks) was 66.7% and 45.6%, respectively. The cold stratification delayed seed germination by about 3 weeks. In the warm stratification experiment (0, 4, 8, or 12 weeks), the final germination percentage was 21.1%, 27.8%, 41.1%, and 57.8%, respectively, 20 weeks after sowing. The embryos of the T. polyphylla seed grew in relatively warm temperatures (23℃). GA3 application overcame seed dormancy and promoted germination. Following GA3 treatment (0, 10, 100, or 1000 ㎎/L), the final germination percentage was 33.3%, 45.0%, 42.5%, and 72.5%, respectively. These results suggest that the T. polyphylla seeds had non-deep simple morphophysiological dormancy (MPD) and GA3 treatment could be used as a substitute for warm stratification for breaking seed dormancy. To our knowledge, this is the first report of seed dormancy characteristics of the genus Tiarella native to Korea.