Background : Cirsium japonicum is a perennial medicinal crop, characterized by the fact that it does not bloom in the first year. Therefore, annual C. japonicum leaves and roots are used as medicinal materials, and biennial do not harvest for seed gathering. In addition, thistle has a very low germination rate, which means that it takes a lot of seed in planting. In order to solve these problems, we conduct to determine the optimum maturity stage and the location of the inflorescence in C. japonicum.
Methods and Results : The test material was a biennial C. japonicum. The harvesting time was sampled at intervals of 10 days (7 treatments) from the beginning of June to the beginning of August, and the location of the inflorescence was sampled from 1 to 3 inflorescence, 4 to 6 inflorescence, and 7 to 9 inflorescence. The buds collected for seed selection were dried for 10 days and used as germination test seeds. Seeds to investigated germination rate were soaked in 70% alcohol for 10 minutes and then washed with distilled water. Then, 20 seeds were arranged in a petri-dish, After standing at 25℃ for 7 days, germinated seeds were counted. As a result of the germination rate, at the beginning of June, the germination rate of seeds collected from 1 to 3 inflorescence was the highest at 35%. In the middle of June, it decreased by 2 times to 3.8%, and the germination rate tended to decrease as location of the inflorescence was lowered. In late June, it decreased to 1 - 2%, and most seeds collected after July did not germinate. The decrease of germination rate according to the harvesting time and the location of the inflorescence, it is considered that sufficient nutrients are delivered in the early stage but the number of immature seeds is decreased as the amount of nutrients is decreased.
Conclusion : Appropriate sampling methods for the production of high quality seed in C. japonicum, the germination rate could be maximized by sampling from 1 to 3 inflorescence at the beginning of June. but, sufficient nutrient supply is required to increase the ripened seeds. Therefore, it is necessary to investigate further research on the additional fertilizer technology.