• Journal of Korean Society of Forest Science
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• v.102 no.2
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• pp.204-209
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• 2013

This study was conducted to determine types of seed dormancy in Sambucus racemosa subsp. pendula (Nakai) H.I. Lim & C.S. Chang, an endemic tree species of Korea, whose seeds have been considered difficult to germinate. Seeds of S. racemosa subsp. pendula were stratified at 25/15 or $5^{\circ}C$ for 0, 6, or 12 weeks (wks) and incubated at 15/6, 20/10, 25/15, or $30/20^{\circ}C$ (12/12 h) under 14 h photoperiod. To determine the effect of $GA_3$ on seed germination of S. racemosa subsp. pendula, seeds were treated with 0, 500, or 1000 ppm $GA_3$ and then germinated at 25/15 or $5^{\circ}C$. The change in embryo length was investigated at 25/15 or $5^{\circ}C$. Seeds given 12 wks of cold stratification germinated to 33.4% at $15/6^{\circ}C$ and to 25.4% for seeds given 6 wks of warm stratification + 12 wks of cold stratification at $20/10^{\circ}C$. At $25/15^{\circ}C$, seeds given 12 wks of warm stratification + 6 wks of cold stratification germinated to 26.0%, and to 28.2% for seeds given 12 wks of warm stratification + 12 wks of cold stratification at $30/20^{\circ}C$. Warm stratification alone did not germinate seeds throughout the experiment, regardless of the thermoperiod. Linear embryos began to grow after 60 days of incubation at 25/15 or $5^{\circ}C$. The embryo length at day 69 increased from 1.4 mm to 1.50 or 1.62 mm at 25/15 or $5^{\circ}C$, respectively. Embryos of S. racemosa subsp. pendula seeds grew better at $5^{\circ}C$ than at $25/15^{\circ}C$. Gibberellin was effective to break seed dormancy of S. racemosa subsp. pendula. Seeds treated with 500 ppm $GA_3$ germinated up to 40.0% at $25/15^{\circ}C$ and to 62.7% for those treated with 100 ppm $GA_3$ at $5^{\circ}C$. With these results, seeds of S. racemosa subsp. pendula have both nondeep complex and intermediate complex morphophysiological dormancy.

• Journal of the korean academy of Pediatric Dentistry
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• v.30 no.4
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• pp.684-695
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• 2003

The aim of this study was to investigate the effect of composite resin components on proliferation and glucan synthesis by cariogenic bacteria, Streptococcus mutans and Streptococcus sobrinus. Light curing pit and fissure sealant was chosen for evluation. Specimens were eluted in deionized water for 10 minutes, 1, 12, and 24 hours. Extracts of specimens were diluted into 1/2, 1/4, and 1/8 with addition of BHI broth and BHI-YS. Bacteria were cultured in media included eluted components, and measured optical density($A_{600}$). The following results were obtained 1. 1/4 concentration of elutes for 10 minutes significantly inhibited the proliferation of S. mutans, whereas 1/2, 1/8 concentration of elutes stimulated it. Also, exacts, especially 1/2, 1/4 concentration, for 1 hours stimulated it. But exacts for 12, 24 hours had not effects on the proliferation of S. mutans. 2. 1/4 concentration of elutes for 10 minutes inhibited growth of S. sobrinus, whereas extracts for 1, 12, 24 hours had not effects on the proliferation of S. sobrinuss. 3. Extracts from composite resin stimulated total growth of S. mutans more than growth control group, where as inhibited it of S. sobrinus. 4. Extracts from composite resin, especially 1/4 concentration of it for 10 minutes increased the formation of water insoluble glucan of S. mutans. But elutes for 1, 12, 24 hours, and 1/8 concentration of it for 10 minutes inhibited it. 5. Except 1/4 concentration of elutes for 10 minutes, extracts decreased the formation of water insoluble glucan of S. sobrinus. 6. Total amount of formated glucan was 3-fold higher in S. mutans than in S. sobrinus.