Non-Deep Physiological Dormancy in Seeds of Crepidiastrum denticulatum (Houtt.) J.H.Pak & Kawano

Understanding the dormancy behavior and germination requirements of Crepidiastrum denticulatum (Houtt.) J.H.Pak & Kawano, a valuable vascular plant native to Korea, is essential for establishing an efficient seed propagation protocol. In this study, we developed a propagation method by examining the effects of temperature, light, gibberellic acid (GA3), and cold stratification to determine whether the seeds possess non-deep physiological dormancy. The light and temperature experiment was conducted under a constant 4 °C and alternating temperature regimes of 15/6, 20/10, and 25/15 °C (12 h day/12 h night). Seeds were incubated under either 12 h light/12 h dark or continuous darkness (24 h). GA3 treatment and cold stratification were conducted only at 15/6 °C or 25/15 °C under the 12 h light/12 h dark photoperiod. All seed treatments were incubated for 8 weeks under their respective temperature conditions. To investigate the influence of GA3, seeds were soaked for 24 h in solutions of 0, 10, 100, or 1000 mg∙L−1 GA3 and then incubated. Cold stratification was tested by storing seeds at 4 °C for 0, 4, 8, or 12 weeks before incubation. Seeds germinated without additional embryo growth, and no physical dormancy due to seed coat impermeability was observed. No germination occurred at 4 °C. Under light conditions, final germination at 15/6, 20/10, and 25/15 °C was 51.8 ± 1.2%, 28.3 ± 3.5%, and 30.8 ± 2.2%, respectively, while under dark conditions it was 37.0 ± 3.1%, 17.3 ± 2.4%, and 13.5 ± 8.5%, respectively. GA3 enhanced germination. Without GA3 treatment, final germination was 41.2% at 15/6 °C and 37.5% at 25/15 °C, whereas with GA3, final germination reached 100% under both temperatures, regardless of concentration. Cold stratification increased germination, improving both initial and final germination compared to the control. Notably, GA3 at 1000 mg·L−1 induced rapid and uniform germination under all temperatures, making it the most effective treatment for the propagation of C. denticulatum seeds, and supporting the conclusion that this species exhibits non-deep physiological dormancy.