• 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.

• Current Research on Agriculture and Life Sciences
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• v.4
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• pp.18-21
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• 1986

This study was conducted to clarify the period of induction and awakening of Liatris spicata corm dormancy, and investigated effect of gibberellin treatment on the dormancy break of corm. The results were obtained as follows ; 1. Ratio of sprouting, shooting and rooting were gradually declined after August 30. These ratio showed the lowest to trend on November 14 during experiment and gradually increased after this time. Ratio were excellent as 100% after January 29. 2. Also, average days for sprouting were the longest on the November 14, but it was rapidly declined after January 29. 3. The period of induction and awakening of corm dormancy were late in September and from late January to early February, respectively, in Daegu, Korea. 4. Effects of GA-treatment on the dormancy break of corm were excellent. Especially, its effects on the dormancy break were the deeper in degree of dormancy, the better.

• Korean Journal of Agricultural and Forest Meteorology
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• v.8 no.2
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• pp.116-124
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• 2006

Remarkable winter season warming has been observed in East Asian countries during the last century. Accordingly, significant effects on dormancy and the resulting budburst of deciduous trees are expected. However phenological observations are rare and insufficient compared with the long-time climate records in the same region. A chill-day accumulation, which can be estimated from daily maximum and minimum temperature, is expected to make a reasonable proxy for dormancy depth of temperate zone fruit trees. To simulate dormancy depth during 1921-2004, a chill-day model parameterized for 'Campbell Early' grapevine, which is the major cultivar grown virtually anywhere in South Korea, was applied to daily temperature data at 8 locations in South Korea. The calculations showed that the chilling requirement for breaking endo-dormancy of this grapevine cultivar can be satisfied by mid-January to late February in South Korea, and the date was delayed going either northward or southward from the 'Daegu-Jeonju' line crossing the middle of South Korea in the east-west direction. Maximum length of the cold tolerant period (the number of days between endo-dormancy release and forced dormancy release) showed the same spatial pattern. When we divide the 83 years into 3 periods (I: 1921-1950, II: 1951-1980, and III: 1981-2004) and get the average of each period, dormancy release date of period III was accelerated by as much as 15 days compared with that of period I at all locations except Jeju (located in the southernmost island with subtropical climate) where an average15-day delay was predicted. The cold- tolerant period was also shortened at 6 out of 8 locations. As a result, budburst of 'Campbell Early' in spring was accelerated by 6 to 10 days at most locations, while inter-annual variation in budburst dates was increased at all locations. The earlier budburst after the 1970s was due to (1) warming in winter resulting in earlier dormancy release (Incheon, Mokpo, Gangneung, and Jeonju), (2) warming in early spring accelerating regrowth after breaking dormancy (Busan and Jeju), and (3) both of them (Seoul and Daegu).

• KOREAN JOURNAL OF CROP SCIENCE
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• v.22 no.1
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• pp.45-51
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• 1977

The studies were carried to know the effects of GA$_3$, Ethrel and $H_2O$$_2$ on dormancy and germination in ginseng seeds. GA$_3$ stimulated the embryo growth and increased dehiscent (Kaekapp) ratio of the seeds for more than Ethrel and $H_2O$$_2$ GA$_3$ not only increased germination ratio but also shortened the period of germination. Ethrel and $H_2O$$_2$ showed no effects on the germination and there were no significant differences among the treatment levels of GA$_3$. The slow germination of ginseng seeds seemed to be mainly due to the dormancy of endosperm or seed coat rather than of embryo.

• Korean Journal of Plant Resources
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• v.31 no.4
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• pp.372-377
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• 2018

This study was investigated the effect of immature rhizome production according to harvest times-based treatment method for seed production of Gastrodia elata. The results revealed that when the tuber weight of G. elata harvested in spring (GEHS) was ${\geq}100g$, the rate of artificial fertilization, protocorm formation, and immature rhizome formation was 90.9%-94.8%, 3.1%-5.4%, and 10.1%-15.3%, respectively. When G. elata harvested in fall (GEHF) was treated at a low temperature for 4 weeks or more, the rate of artificial fertilization, protocorm formation, and immature rhizome formation was 70.4%-87.6%, 2.2%-2.6%, 8.7%-9.5%, respectively. Therefore, to produce seeds and immature rhizomes, GEHS must have tubers of more than 100 g, whereas GEHF requires breaking dormancy by low-temperature treatment for 4 weeks or more. Compared with those of GEHS, the rate of artificial fertilization, protocorm formation, and immature rhizome formation was lower in GEHF; however, it was higher than those in the natural germination state. Thus, it can be expected that G. elata can be produced throughout the year by ensuring that the seeds and immature rhizomes of G. elata are produced using a constant tuber weight and by breaking dormancy with low temperature treatment.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.59 no.1
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• pp.22-26
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• 2014

This research was implemented to investigate pre-harvest sprouting characteristics in two Korean rice cultivars, Shindongjin (SDJ) and Hopum (HP). The panicles of both varieties were sampled after 15 days after heading (DAH) to 60 DAH at intervals of 5 days. As soon as sampled, the panicles were imbibed in water for 14 days at $25^{\circ}C$ to determine the vigor and germination ability of seeds according to location on panicle. To investigate the cause of non-germination of seeds in panicles, tetrazolium test and dormancy breaking were performed. The preharvest sprouting of HP started at 20 DAH while that of SDJ began at 30 DAH. The germination of seeds located in high rank branches within a panicle and the terminal seeds within a branch were earlier and faster and the germination patterns were same in both cultivars. The times at more than 50% of germination in a panicle were 35 DAH (57.0%) in HP and 45 DAH (56.8%) in SDJ. Preharvest sprouting was more than 80% at 50 DAH (82.6% of HP, 92.3% of SDJ) and more than 99% at 60 DAH (99.5%, 99.4%, HP and SDJ). These results indicated that the rate of PHS in a panicle increased with accumulation of the days after heading. The cause of non-germinated seeds at 15-25 DAH in panicle was immature embryo. After 30 DAH, however, when the non-germinated seeds were hulled, they started to germinate due to dormancy breaking, in which the germination percentage was higher in SDJ than HP. In conclusion, the pre-harvest sprouting varied according to days after heading, the seed position on panicle, and the dormancy intensity of varieties.

• Korean Journal of Plant Resources
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• v.32 no.6
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• pp.683-688
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• 2019

This study was conducted to determine the number of days required to break a plant's dormancy and promote subsequent crop growth in new varieties of Gomchwi through the 4℃ treatment. Three new varieties of Gomchwi namely, 'Sammany', 'Gommany', and 'Damogy' were observed in this study. The rate of leaf emergence of 'Sammany' after 15-day of 4℃ treatment was 100%, while 'Gommany', and 'Damogy' took 20-days and 10-days, respectively to reach to 97.9% rate of leaf emergence. After 10-days of 4℃ treatment, 'Damogy' grew faster than the other varieties. and Harvest time for 'Damogy' was on January 18^th, after 5-days of 4℃ treatment and yield was observed to be the highest at 15-days of 4℃ treatment. 'Sammany' was next with a minimum of 10-days of 4℃ treatment, although 15-days is more preferred for better harvest. 'Gommany' on the other hand, did not grow enough for harvest by January 18^th, and its harvest time was delayed to January 31^st. It needed a minimum of 15-days and preferentially 20-days of 4℃ treatment to grow normally and be ready for harvest. The plant height, leaf length and leaf petiole length appeared to grow better by extending duration of the 4℃ treatment. The number of leaves of 'Sammany' and 'Gommany' varieties was three leaves for the 5-days treatment which may be due to the incomplete breaking of dormancy. Regarding the yield per plant, 'Sammany' yielded 112.3 grams (g) in 15-days treatment, and 'Gommany' yielded 106.5 g in 25-days treatment. In the case of 'Damogy', it yielded 123.5 g and 183 g in the 10-days and 25-days treatment respectively. It is concluded that 'Damogy', 'Sammany' and 'Gommany requires 10, 15, and 20 days of 4℃ treatment to break the plant's dormancy and promote better plant growth.

• Korean Journal of Medicinal Crop Science
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• v.3 no.2
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• pp.111-115
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• 1995

This study was carried out to investigate the effect of some plant growth regulators on the germination and seedling growth of Wasabia japonica Matsum seeds. The seeds were soaked in different concentration of indolacetic acid(LAA), indolbutyric acid(IBA), $GA_3\;GA_4$, Benzyladenine(BA) and kinetin, and the germination percent, the average germination day and the growth of seedlings were measured. The seeds were released from dormancy and the germination percent was considerably increased when the seedcoat was removed. $GA_3,\;GA_4,$ BA and kinetin were effective in breaking the dormancy, but LAA and IBA were not effective. $GA_4$, BA and kinetin were more effective in accelerating germination of dormancy seed than $GA_3$. The applications of BA combined with $GA_3$ l00ppm showed higher germination percent than that of BA alone within the range 50ppm and 100ppm. Root, hypocotyl and petiol of seedling overgrew by the application of $GA_3\;and\;GA_4$. But effects of BA and kinetin were good on seedling growth compared with those of $GA_3\;and\;GA_4$. Therefore, BA and kinetin could be use for dormancy breaking of seed instead of $GA_3$.

• Journal of Crop Science and Biotechnology
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• v.11 no.3
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• pp.199-204
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• 2008

Seed dormancy behavior of weed seeds is a critical determinant of their survival rates in a given cropping system as it helps the weeds to evade herbicides and other weeding practices. We investigated the effects of red light, alternating temperature, stratification duration and different doses of nitrogen containing compounds alone or in combination with red light on breaking seed dormancy of Chenopodium album L. The application of red light(80 ${\mu}mols^{-1}m^{-2}$) significantly increased seed germination of C. album in all treatments. Germination rates of 12 h incubated seeds were highest under 20 min of red light irradiation than 1 min, 5 min and 10 min treated seeds. Germination rate was significantly higher at alternating temperatures of $25^{\circ}C\;and\;5^{\circ}C$ for 12 h each with an irradiation of red light(80 ${\mu}mols^{-1}m^{-2}$) for 10 min than other treatments. Stratification period of 15 days significantly stimulated germination percentage of seeds incubated in dark, although 5 days of stratification along with red light application for 10 minutes exhibit similar effects on seeds. Seed germination was also enhanced by nitrogen containing compounds like $NaNO_2,\;KNO_3,\;NH_4Cl\;and\;NH_4NO_3$. We observed that seed germination increased significantly with 25 mM $KNO_3$ and 10 mM $NH_4NO_3$ in dark condition, while $NaNO_2$ and $NH_4Cl$ enhanced seed germination under red light irradiation. It was concluded that red light alone or synergized with alternating temperatures, stratification and nitrogen compounds, especially nitrite and ammonium enhanced seed germination of C. album. Thus, the red light can play a vital role in present and future weed management strategies.

• FLOWER RESEARCH JOURNAL
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• v.19 no.2
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• pp.96-102
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• 2011

The objective of study was carried out to find a proper entrance date for breaking dormancy depending on cutting and entrance date into greenhouse investigating plant growth and flowering characteristics of chrysanthemum 'Baekma'. Days to visible bud formation and days to flowering were increased as cutting date was delayed. The flowering rate of cutting on September 18 was 100% while cutting on October 30 did not induce flower bud formation. Flower characteristics were surveyed after 'Baekma' and 'Jinba' rooted cuttings were planted on September 10. Branching formation rate of 'Baekma' was gradually increased as entrance date was delayed while that of 'Jinba' was about 70-80% regardless of entrance date. Lethality of 'Baekma' moving into greenhouse on December 20 was 1.5% by cold injury. 'Jinba' started to die on November 10 by cold injury and lethality of 'Jinba' moving into greenhouse on December 20 was 21.7%. Thus, lethality of 'Jinba' was about 5-14 times higher than that of 'Baekma'. Days to visible bud formation and days to flowering were decreased as entrance date was delayed in chrysanthemum 'Baekma'. Days to visible bud formation of entrance date on November 10 and December 10 were 67.9 and 50.3, respectively. On the other hand, that of 'Jinba' was increased until entrance date on December 10 and decreased on December 20. Based on these results, it was suggested that dormancy of 'Baekma' was started at late September and completed at late October.