Non-deep physiological dormancy in seeds of Euphorbia jolkinii Boiss. native to Korea

Background Euphorbia jolkinii Boiss. is a perennial species native to Jeju Island and the southern coastal area of Korea. Particularly on Jeju Island, the yellow flowers of E. jolkinii Boiss. have a high ornamental value because of their contrast with basalt. This study was conducted to investigate the effects of different temperatures (5, 15, 20, and 25 °C) and gibberellic acid (GA3) concentrations (0, 10, 100, or 1000 mg/L) on seed dormancy and germination of E. jolkinii. In addition, we classified the seed dormancy type and compared types with those of other species in the same genus. Results The number of seeds with viable embryos and endosperms was approximately 66%. The final germination percentages at 5, 15, 20, and 25 °C were 51.7%, 83.5%, 2.6%, and 0.0%, respectively. In GA3 concentration experiments, the final germination percentages of 0, 10, 100, and 1000 mg/L were 83.5%, 91.7%, 79.1%, and 83.4%, respectively, at 15 °C conditions, and 0.0%, 6.9%, 13.2%, and 27.3%, respectively, at 25 °C. Conclusions Germination improved at temperatures of 15 °C or lower. Furthermore, GA3 treatment effectively reduced germination times. Thus, the seeds of E. jolkinni were classified as having non-deep physiological dormancy.