Gun Mo Kim

Seed dormancy and germination traits of Campanulaceae species in relation to ecological factors remains unclear. Hence, we clarified the seed germination characteristics of five Campanulaceae species (Adenophora triphylla (Thunb.) A.DC., Asyneuma japonicum (Miq.) Briq., Campanula punctata Lam., Codonopsis pilosula (Franch.) Nannf., and Lobelia sessilifolia Lamb.) native to Korea. Seeds were subjected to varying temperatures, cold stratification (CS) durations, and gibberellic acid (GA₃) concentrations. Seeds of all species imbibed water readily, suggesting the absence of physical dormancy. For A. triphylla, A. japonicum, and L. sessilifolia, suitable seed germination occurred under elevated temperature conditions: 74.0 ± 6.2%, 37.0 ± 1.0%, and 26.0 ± 3.5% germination, respectively, at 25 °C, and 79.0 ± 3.8%, 38.0 ± 3.5%, and 62.0 ± 8.4% germination, respectively, at 25/15 °C (day/night) after 7 weeks after incubation. Germination of C. punctata and C. pilosula was consistently low across all temperatures. CS treatment resulted in significant final germination improvement to ~70.0% in four species, excluding C. pilosula. GA₃ application significantly enhanced seed germination by ~60.0% across all species, with the most notable effects observed at 1000 mg∙L⁻¹. Overall, Campanulaceae species seeds are permeable, and pre-treatment with CS and GA₃ is required for effective seed germination.

Rhodotypos scandens (Thunb.) Makino is known to have a seed dispersal that is thick and stony (endocarp + seeds) and has potential as a landscaping tree seed. In several Rosaceae species, seeds are covered with a hard endocarp, making the internal seeds water-impermeable and germination difficult. Here, we analyzed the morphoanatomical traits and germination properties of R. scandens seeds. To identify ideal seed propagation conditions, we immersed R. scandens seeds in sulfuric acid for varying durations and subjected them to phytohormone (gibberellic acid A3 and fluridone) and a cold stratification (CS) (5 °C) treatment after endocarp removal (ER). The R. scandens stony seeds did not increase in mass by ≥25.0%. Following ER, the seed mass increased by ≥50.0% with water absorption when compared to the initial dry mass. Seed surfaces showed damage and cracks through scarification after 1 h of immersion in sulfuric acid, failing to germinate. A combination of ER, phytohormone treatment, and CS improved seed germination compared to ER alone (26.0 ± 5.3%). Overall, R. scandens seeds showed a dispersal with a hard endocarp from the parent plant, and a pre-treatment with ER, phytohormones, and CS was required for effective seed propagation.

Prunus spachiana (Lavallée ex Ed.Otto) Kitam. f. ascendens (Makino) Kitam leaves exert natural anti-inflammatory effects by inhibiting nitric oxide formation. P. spachiana flowers bloom earlier than other Prunus spp. and thus could serve as a valuable resource for the horticulture and pharmaceutical industries. However, its seed dormancy class and germination traits remain uncharacterized. Thus, this study aimed to characterize the seed dormancy and germination of P. spachiana. Imbibition, phenological, and move-along experiments were performed, and the effects of H₂SO₄ treatment, hormone soaking, warm/cold stratification, and endocarp removal on germination were explored. Observation revealed that ripe seeds of P. spachiana contain developed embryos and are water permeable. Radicle and shoot emergence began in March and April, respectively, under natural conditions in the year following production. No seed germination was observed after 30 days of incubation at 4, 15/6, 20/10, or 25/15 °C under light/dark conditions, indicating the physiological dormancy of the seeds. Germination increased with prolonged stratification and was affected by incubation temperature. Seed scarification by H₂SO₄ and soaking with gibberellic acid (GA₃) and fluridone were ineffective in breaking dormancy. However, GA₃ soaking of the seeds after endocarp removal effectively induced germination (100%). These results indicate that P. spachiana seeds exhibit intermediate physiological dormancy.