This study was performed to identify optimal harvesting time of ginseng seeds and to examine the effect of $GA_3$ treatment for improvement of seed stratification rate. Ginseng seeds harvested from Land race, Chunpoong and Yunpoong cultivar in July 20 were tested for stratification rate. It was shown that stratification rates of land race, Yunpoong and Chunpoong cultivar were 94.1%, 93.1%, and 82.6%, respectively. Seeds of Chunpoong cultivar harvested 10-15 days later showed a comparable stratification rate to that of Land race, indicating that late harvest of Chunpoong seeds is beneficial for the increase of stratification rate. The higher stratification rate was found in mature seeds (92.3%) than immature seeds (37.8%), both of which were harvested in July 20. Stratification rate of mature seeds harvested in July 15 was 87.5%, demonstrating optimal harvesting time of ginseng seeds with higher stratification rate is after mid-July. An exponential growth of endosperms of ginseng seeds was observed from early June to mid-June and then slow growth was observed. There was no obvious growth of embryos from fertilization to mid-August. After the this time, embryos quickly grew until late October. Thus, appropriate stratification control is essential during the period (from early September to late October) in order to optimize embryo growth and development. While no increase of stratification rate was observed in seeds treated with 50 ppm of $GA_3$, significant increases were observed in seeds treated with 100 ppm of $GA_3$. At this concentration of $GA_3$, the stratification rate of Land race, Chunpoong and Yunpoong cultivar was 95.0%, 95.3%, and 96.5%, respectively.
Ahn SD, Kwon WS, Chung CM and Son ER. (1986). Study on the optimum time of seed production and development of embryo in Panax ginseng C. A. Meyer. Korean Journal of Crop Science. 31:123-128.
Choi JH, Lee JG, Seong ES, Yoo JH, Kim CJ, Lee GH, Ahn YS, Park CB, Lim JD and Yu CY. (2013). The germination characteristics of seed by storage and germination temperature in Astragalus membranaceus. Korean Journal of Medicinal Crop Science. 21:461-465.
Kim YC. (2012). Classification of the morphological characteristics of ginseng(Panax ginseng C. A. Meyer) germplasm and selection of useful resources. Ph. D. Thesis. Chungnam National University. p.1-3.
Korea Customs Service(KCS). (2014). http://www.customs.go.kr.
Korea Seed & Variety Service(KSVS). (2014). http://www.seed.go.kr.
Korea Tobacco ＆ Ginseng(KT&G). (1996). The latest Korean ginseng-Culture part. Central Research Center of Korea Tobacco & Ginseng. Daejeon, Korea. p.42-44.
Kwon WS and Lee JM. (1997a). Changes of cytokinins and gibberellin contents during low temperature storage of dehisced ginseng seeds. Journal of Korea Society Horticulture Science and Biotechnology. 38:111-115.
Kwon WS, Baek NI and Lee JM. (1997b). Identification and changes of physiologically active substances during chilling storage of dehisced ginseng seeds. Journal of Ginseng Research. 21:13-18.
Kwon WS, Jung CM, Ahn SD and Choi KT. (1986). Effects of growth regulators on the germination of Panax ginseng C. A. Meyer. Journal of Ginseng Research. 10:159-166.
Lee JC, Byen JS and Proctor JTA. (1986). Dormancy of ginseng seed as influenced by temperature and gibberellic acid. Korean Journal of Crop Science. 31:220-225.
Lee SW, Park KC, Lee SH, Jang IB, Park KH, Kim MR, Park JM and Kim KH. (2014). Effect of ferric and ferrous iron irrigation on brown-colored symptom of leaf in Panax ginseng C. A. Meyer. Korean Journal of Medicinal Crop Science. 22:32-37.
Rhim SY, Sohn JK, Ryu TS, Kwon TR, Choi JK and Choi HJ. (2010). Analysis for the major traits and genetic similarity of native ginseng(Panax ginseng C. A. Meyer) collections in Korea. Korean Journal of Breeding. 42:488-494.
Rural Development Administration(RDA). (2009). Ginseng cultivation standard farming text book-103(Revised Ed.). Rural Development Administration. Suwon, Korea. p76-77.
Rural Development Administration(RDA). (2012). Good agricultural practice of ginseng(Revised Ed.). Rural Development Administration. Suwon, Korea. p.77-79.
Stoltz LP and Snyder JC. (1985). Embryo growth and germination of American ginseng seed in response to stratification temperature. Horticultural Science. 20:261-262.