• Korean Journal of Plant Resources
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• v.36 no.6
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• pp.580-587
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• 2023

Androsace septentrionalis is a grass species restricted to North Korea; however, it is at the brink of extinction due to habitat loss and environmental changes caused by natural disasters and anthropogenic activities. This study was conducted to characterize the dormancy conditions of A. septentrionalis in an effort to conserve this North Korean plant resource. For this purpose, the morphological characteristics and vigor of A. septentrionalis seeds were examined, and its germination characteristics under different temperature conditions (15/6℃ and 25/15℃ ), low-temperature stratification, and gibberellin (GA₃) treatment were determined. The results revealed that A. septentrionalis exhibits non-deep type morpho-physiological dormancy, and low-temperature stratification treatment was not effective in breaking the dormancy of A. septentrionalis seeds. Meanwhile, GA₃ treatment significantly increased the mean germination time, rate, and speed of the seeds. The optimal conditions for the germination of A. septentrionalis seeds were 25/15℃ fluctuating temperature and 500 mg·L¹ GA₃ treatment. The results of this study are useful for the mass propagation of A. septentrionalis.

• Asian Journal of Turfgrass Science
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• v.15 no.1
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• pp.15-20
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• 2001

Two types of annual bluegrass have been reported, and those consist of annual type (Poa annua ssp. annua) and perennial type (Poa annua ssp. reptans). As a weed, annual bluegrasses are commonly found in putting greens and fairways in many golf courses. Due to its strong competitiveness such as tremendous seed reproduction rate a year, prostrate growth habit, and no herbicide availability, annual bluegrasses have been considered as one of the most hard-to-control weeds in turf management systems. A growth chamber study was conducted to determine seed dormancy and to understand seed germination characteristics of annual bluegrass (Poa annua ssp. annua). Freshly harvested seeds showed 80 and 55% germination at 30 and $35^{\circ}C$, respectively, indicating that the optimum temperature of annual bluegrass is $30^{\circ}C$. However, the seed germination occurred only under light condition at any given temperature. This result demonstrated that light is prerequisite for the seed germination, and no primary dormancy of annual bluegrass seed exists. Secondary seed dormancy induced by unfavorable temperatures and dark condition was broken through 4 to 6 wk-storage at $4^{\circ}C$ with moisture, and the stored seeds germinated at $20^{\circ}C$ even under the dark. In red and far-red light trial, fresh seeds resulted in 40% germination under red while no seed germination occurred under far-red light condition, indicating that phytochrome Pr and Pfr could be related to annual bluegrass seed germination. When the far-red light replaced the red the germination was recovered, but this reversibility did not reach to the germination level under the red light only. This result implied that other lights than red and far-red would play an important role on seed germination of annual bluegrass.

• Journal of Bio-Environment Control
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• v.6 no.3
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• pp.143-150
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• 1997

In order to produce young leaf of butterbur(Petasites japoflicus MAX.) in early spring, the planting date and relationship between abscisic acid(ABA) content and dormancy were investigated. Under open field condition, the dormancy of rootstock was initiated in the beginning of October, was the deepest in the middle of November and was completely broken in the end of December. When those periods were converted by the low accumulation hour below 5$^{\circ}C$, 900 hours were required approximately. This means that the rootstock needs for dormant breaking necessitates under the low temperature. In relationship between growing period and ABA content, the ABA in root-stock did not exist during maximum growing period, from April to September. This means that the ABA together with other substances in rootstock can be transferred to the shoot part with sprouting. While shoot part withered by decreacing the open field temperature since October, the ABA intiated to exist in rootstock. This means that the ABA in the shoot part can be transferred to the rootstock part. Therefore, it was concluded that the ABA which has been known that inhibiting growth and inducing dormancy was closely related with dormancy of rootstock.

• Clinical and Experimental Reproductive Medicine
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• v.41 no.3
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• pp.125-131
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• 2014

Objective: Under estrogen deficiency, blastocysts cannot initiate implantation and enter dormancy. Dormant blastocysts live longer in utero than normal blastocysts, and autophagy has been suggested as a mechanism underlying the sustained survival of dormant blastocysts during delayed implantation. Autophagy is a cellular degradation pathway and a central component of the integrated stress response. Reactive oxygen species (ROS) are produced within cells during normal metabolism, but their levels increase dramatically under stressful conditions. We investigated whether heightened autophagy in dormant blastocysts is associated with the increased oxidative stress under the unfavorable condition of delayed implantation. Methods: To visualize ROS production, day 8 (short-term dormancy) and day 20 (long-term dormancy) dormant blastocysts were loaded with $1-{\mu}M$ 5-(and-6)-chloromethyl-2', 7'-dichlorodihydrofluorescein diacetate, acetyl ester (CM-$H_2DCFDA$). To block autophagic activation, 3-methyladenine (3-MA) and wortmannin were used in vivo and in vitro, respectively. Results: We observed that ROS production was not significantly affected by the status of dormancy; in other words, both dormant and activated blastocysts showed high levels of ROS. However, ROS production was higher in the dormant blastocysts of the long-term dormancy group than in those of the short-term group. The addition of wortmannin to dormant blastocysts in vitro and 3-MA injection in vivo significantly increased ROS production in the short-term dormant blastocysts. In the long-term dormant blastocysts, ROS levels were not significantly affected by the treatment of the autophagy inhibitor. Conclusion: During delayed implantation, heightened autophagy in dormant blastocysts may be operative as a potential mechanism to reduce oxidative stress. Further, ROS may be one of the potential causes of compromised developmental competence of long-term dormant blastocysts after implantation.

• Journal of Plant Biotechnology
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• v.7 no.1
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• pp.75-80
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• 2005

Eleutherococcus senticosus (also called Acanthopanax senticosus), belonging to Araliaceae family, has been used as an important medicinal woody plant. Mature seeds of Eleutherococcus senticosus have rudimentary (extremely immature) zygotic embryos and require a long-term stratification for about 18 months to induce germination. Here, through the methods of endosperm removal and other exogenous treatments, we investigated the factors for inducing rudimentary embryos by in vitro culture, Rudimentary zygotic embryos in seeds were at globular to heart-shaped stage at about $250{\mu}m$ in length just after harvest of fruits. When the seeds without testa were cultured on 1/2 MS (Murashige and Skoog 1962) medium, they did not germinate regardless of medium and sucrose concentrations but the removal of endosperm tissue markedly stimulated the growth of rudimentary zygotic embryos. The embryo reached ear-lier maturation, once when the endosperm surrounding the rudimentary embryos was removed. Rudimentary zygotic embryos developed cotyledons within 3 weeks of culture after endosperm emoval. However, post-mature zygotic embryos failed to germinate though they were morphologically normal, indicating another dormancy of embryos. $GA_3\;(2.0\;\cal{mg/L})$ and/or charcoal ($0.2\%$) treatment rapidly enhanced the germination of zygotic embryos. These results suggest that E. senticosus seeds have double dormancy; i. e. morphological rudimentary dormancy influenced by surrounding endosperm and physiological dormancy after post-maturation of zygotic embryos. Based on the above findings, we established the rapid germination of rudimentary zygotic embryos by in vitro culture of excised seeds with endosperm removal and $GA_3$ treatment.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.40 no.6
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• pp.705-710
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• 1995

In order to find out the effect of rainfall at harvesting season on germination of malting barley, the seeds sampled from Cheju island and southern part of Korea were examined. The germination rate of seeds from Cheju island where rainfall was frequent at harvesting season, ranged from 46 to 71%, even though disease infection of the seeds was not that serious as would be expected. High sugar content of seed was resulted from the degradation of carbohydrates during the harvest season. From TZ test the rainfall - affected seeds were found to be highly viable but in the state of secondary dormancy. Results of cold germination test showed that the seeds were recovered from the secondary dormancy. Therefore, it was recommended that the seeds affected by the rainfall at harvesting season should be utilized after 12 months when the dormancy period terminated. The germination percent of the seeds was significantly enhanced by prechilling and / or 1 ppm gibberellic acid treatment. Different seed lots showed different rate of germination and the degree of dormancy.

• Proceedings of the Ginseng society Conference
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• 1984.09a
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• pp.49-55
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• 1984

Dormant one-year-old ginseng roots were subjected to a range of stratification temperatures and time to define effective limits to these parameters and to quantify their effect on terminating dormancy. Effective storage temperatures tested ranged from $0^{\circ}C\;to\;9^{\circ}C.$ A low percentage of roots produced tops with as few as 30 days in stratification; however, 75 to 90 days were required for 100 percent emergence. Days to emergence, after planting, decreased with increased days in storage thru the maximum storage time of 120 days. The number of days of dormancy was relatively constant, near 126.5 days, over the range of effective temperatures and acceptable storage times. The minimum period of dormancy was associated with 75 days in storage at $3^{\circ}C.$ Root growth rate, after emergence, was greatest following 105 days of stratification. The frequency distribution of emergence with days in stratification suggests the potential of selecting for strains of ginseng with low chilling needs for satisfying dormancy requirements.

• Korean Journal of Plant Resources
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• v.19 no.1
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• pp.45-49
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• 2006

This study has been conducted to find out the possibility of the winter production for pot cultured plants, such as P. sieboldii, P. modesta var. fauriae and D. smilacinum in highland, 800 meter above sea level by early breaking dormancy. Low temperatures for breaking dormancy were treated for 300, 500, 700 and 900 hours under $5^{\circ}C$ in incubators and, then these plants were moved to greenhouse controlled at $10^{\circ}C$ of night temperature. Results showed that P. modesta var. fauriae and D. smilacinum, and P. smilacinum required more than 500 hours and 700 hours of low temperature $5^{\circ}C$ for breaking dormancy, respectively.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.10
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• pp.85-90
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• 1971

Dormancy breaking methods were studied on Avenasterilis seeds. The treatments were: application of alcohol, hot water, low temperature, pure oxygen, thiourea and gibberellic acid. Thiourea treatment with 3 different concentrations (0.25 x 10$^{-2}$ M, 0.625 x 10$^{-2}$ M, 1.25 x 10$^{-2}$ M) had little effect in breaking dormancy. Gibberellic acid treatment applied at 5ppm, 50ppm, 500ppm were effective and maximum germination was obtained with 500ppm. Low temperature treatment at 3$^{\circ}C$ for a week in a refrigerator was also very effective in breaking dormancy. Other treatments were not effective. In all cases, primary seeds germinated significantly better than secondary seeds. Different A. sterilis strains varied significantly in their response to gibberellic acid treatment. Different concentrations of gibberellic acid also gave significantly different responses in breaking dormancy.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.53 no.4
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• pp.421-426
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• 2008

Freshly harvested seed of Chinese milk vetch (Astragalus sinicus L.; CMV) was strongly dormant because of hardseedness. Seeds of freshly harvested germinated only 8% while clipping the seed coat completely overcome the innate dormancy, which indicates inhibition of germination of the seed is mainly due to seed coat (87%). The dormant (intact) hard seeds did not imbibe water whereas the non-dormant (clipped) seeds took up rapidly. In natural environment condition, the hard seed coat dormancy was broken only after 5 months after seed harvest. To break such a strong seed coat dormancy, the chemical and heat treatments were effective. Concentrated sulfuric acid was more effective than dry heat and hot water treatments. Hot water treatment improved germination but the germination percentage was less than 41%. Treatments increased germination due to its effect on the seed coat integrity. A scanning electron microscope reveled that disruption of seed coat layers and subsequent development of numerous crack in the hilum region of the seed and on the seed coat surface of concentrated sulfuric acid treatment and formation of cracks in the dry heat treatments, respectively, were observed in the seed coat surface, which served as water entry points.