Seed Dormancy and Germination of Scrophularia koraiensis, an Endemic Species in the Korean Peninsula

This study aimed to develop seed-based mass propagation techniques for the conservation and horticultural and medicinal uses of Scrophularia koraiensis Nakai, an endemic plant in the Korean Peninsula. Seeds were collected from four different locations (accessions) and subjected to untreated (control), gibberellic acid (GA)-only treatment, cold stratification-only treatment, or a cold stratification + GA treatment. Except for seeds collected from one location, the control group exhibited low germination of below 20% in all other locations. However, the GA-only and cold stratification-only treatments released seed dormancy and promoted germination compared with the control. In particular, the cold stratification-only treatment at 5 °C for 4 weeks resulted in about 80% germination in all accessions and demonstrated positive effects on germination speed and uniformity. These findings indicated that S. koraiensis seeds exhibit non-deep physiological dormancy (PD). Upon comparing the seed dormancy classes across various species of Scrophularia, native to different continents and countries, we confirmed that PD is very well conserved in the genus Scrophularia. Therefore, the study outcomes will provide fundamental and practical insights into the seed dormancy and germination characteristics of various Scrophularia species for future studies.