• KOREAN JOURNAL OF CROP SCIENCE
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• v.38 no.4
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• pp.297-303
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• 1993

Seedling emergence and .stand establishment in dry-seeded rice is unstable at present due to deep seeding, low temperature at seeding time, excessive drought or raining etc. This experiment was conducted to elucidate the effect of gibberellic acid(GA$_3$) on the seedling emergence and growth in dry-seeded rice. GA$_3$, IBA and Metalaxyl were treated by seed-soaking or-spray. Hwaseongbyeo, a japonica rice, was used. The seed-soaking treatment with GA$_3$ significantly increased the seedling emergence and plant height as compared with untreated seed. However, no difference was observed in IBA and Metalaxyl treatment. The optimum concentration of GA$_3$ to promote the seedling emergence and growth in dry-seeded rice was about 100ppm for seed-soaking and about 200ppm for seed-spray treatment. The seed-spray treatment of GA$_3$ with 200ppm promoted earlier and faster seedling emergence and elongated seedling height as compared with untreated seed.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.42 no.1
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• pp.42-48
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• 1997

Ten days old rice seedlings were treated with NaCl and the contents of endogenous hormones such as GA$_3$, ABA, IAA and zeatin were measured by ELISA. Water content and seedling growth were decreased as the salt concentration was increased. GA$_3$ increased up to 24 hours after NaCl treatment and decreased thereafter. ABA was raised by four times in 48 hours after NaCl treatment. IAA and zeatin decreased as the NaCl concentration and duration of treatment increased. GA$_3$ and ABA showed positive and negative correlation with the water content in the plant tissue, respectively.

• Korean Journal of Microbiology
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• v.12 no.4
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• pp.188-193
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• 1974

Effects of GA and IAA on the respiratory and photosynthetic activity of each growth stage during the synchronous culture of Chlorella ellipsodiea, were investigated. 1) GA ($2{\times}10^{-8}M$) affected most insignificantly on the respiratory activity of the stages Dn, Da, $L_1$, $L_2$, $L_3$-cells but only at $L_4$-cells treated with IAA($10^{-3}/M$) were promoted and $L_3$, $L_4$-cells were suppressed. With the treatment of GA-IAA the effects on respiration of eah stage cells were antagonistic. 2) Photosynthetic activity treated with GA during the each stage of Chlorella cells was promoted and IAA treated-cell were suppressed. The effect of GA-IAA upon the process of life cycle was also antagonistic. 3) It was revealed that respiratory and photosynthetic activity of Chlorella cells by the treatment of GA(($2{\times}10^{-8}M$) and IAA($10{\times}^{-3}/M$) had antogonistic effects.

• Korean Journal of Medicinal Crop Science
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• v.7 no.1
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• pp.16-21
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• 1999

Seed-propagation of Solomon's seal (Polygonatum odoratum) takes 2 years to shorten the period for becoming a practical method. The experiment was done to establish a proper method of breaking the epicotyl dormancy in bulk seed-propagation. Seedlings with a bulbil were treated with $GA_3$ every 2 days for 4 or 8 days and chilling treatments at $3^{\circ}C$ were enforced for 4, 6, 8 or 12 weeks. Emergence- and growth-related characteristics were examined immediately after the treatments, 3 and 6 weeks later. Rate of cotyledonary sheath rupture immediately after $GA_3$ treatment was greater in its 8-day treatment than in 4-day although its effect disappeared later. However, any epicotyl treated with $GA_3$ solution did not elongate so that new seedlings disemerged over the bed soil. That resulted from not breaking the epicotyl dormancy since $GA_3$ did not rupture all of the cotyledonary sheath formed with several sheets and consequently, the solution did not reach it. The $GA_3$ treatment for bulk seed-propagation, therefore, was impractical method. On the contrary, the chilling treatment was able to be applied to the seed-propagation because of getting the cotyledonary sheath rupture and the epicotyl elongation. Seedling emergence and its growth after chilling treatment were influenced by chilling period although required at least over 6-week treatment for satisfactory results.

• Journal of Environmental Science International
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• v.32 no.1
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• pp.77-88
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• 2023

Kadsura coccinea (Lem.) A.C. Smith is used as a medicinal plant and cosmetic material in China and Southeast Asia. To mass-produce Kadsura coccinea seedlings, the effects of gibberellic acid (GA₃) and cold stratification treatments on seed germination were investigated. Seed germination rate with GA₃ treatment was most effective at concentrations of 250 or 500 mg/L. With respect to mean germination time (MGT), mean daily germination, and T₅₀ (days to reach 50% seed germination), the germination-promoting effect was improved as the concentration of GA₃ increased. Stem growth of seedlings was the highest following GA₃ treatments of 250 and 500 mg/L, and the growth promoting effect gradually decreased as the concentration of GA₃ decreased. Root growth was stimulated at GA₃ concentrations of 250-1,000 mg/L. Examination of the effect of stratification treatment for 15, 30 and 60 days at temperatures of 0, 5 and 10℃ on the germination rate revealed that the most stratification treatment temperature was 10℃, and the results improved with longer treatment periods. Altogether, GA₃ and stratification treatments improved the seed germination rate, shortened the MGT, improved germination uniformity, and produced healthy seedlings.

• Korean Journal of Medicinal Crop Science
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• v.24 no.4
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• pp.284-293
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• 2016

Background: Developing new ginseng cultivars is a significant time-consuming process owing to the three years of growth required for ginseng to flower. To shorten the ginseng breeding process, it is necessary to establish rapid progression through each generation. In this study, we examined it was possible to rapidly break ginseng seed dormancy using gibberellic acid ($GA_3$) treatment and alternating temperature. Methods and Results: Seeds were obtained from local variety. Seeds were treated with either $GA_3$ at a concentration of $100mg/{\ell} $, constant temperature ($-2^{\circ}C$ and $2^{\circ}C$), alternating temperature ($2^{\circ}C$ followed by $-2^{\circ}C$, followed by $2^{\circ}C$) or a combination $GA_3$ and temperature treatment. Following experimental treatment, seeds were sown into trays and placed in a greenhouse. Low germination rates were observed in seeds that did not receive $GA_3$ treatment, which were similar following $2^{\circ}C$ and $-2^{\circ}C$ constant temperature treatment. Germination rates increased in proportion to $GA_3$ and more so when combined with alternating temperature treatment. In additon, stem and leaf lengths of the resulting ginseng plants were increased following $GA_3$ treatment, although no synergistic effect was observed with alternating temperature treatment. Conclusions: These results suggest that a combination $GA_3$ and alternating temperature treatment enhances ginseng seed germination, which can contribute to shortening the time required to progress through a single ginseng generation for breeding.

• Journal of the Korean Vacuum Society
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• v.15 no.2
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• pp.216-222
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• 2006

In this paper, we investigated the effect of hydrogen-plasma (H-plasma) treatment on the electrical and optical properties of a quantum dot infrared photodetector (QDIP) with a 5-stacked InAs dots in an InGaAs/GaAs well structure and $Al_{0.3}Ga_{0.7}As/GaAs$ SL (superlattice) current blocking layer. It has been observed that H-plasma treatment didn't affect the band structure of QDIP. It has been also observed that the H-plasma treatment on the QDIP not only enhance the electrical property of QDIP by curing the defect channels in $Al_{0.3}Ga_{0.7}As/GaAs$ SL but also introduce defects in QDIP structure. The H-plasma treatment for 10 min with 20 W of RF power provided the lowest dark current, which made it possible to measure the photo-current (PC) of QDIP whose PC was not detectable without the H-plasma treatment due to the high dark current.

• Journal of Radiation Industry
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• v.6 no.3
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• pp.281-287
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• 2012

The model plant, Arabidopsis thaliana is the subject of an international genome research project. Massive doses of ionizing radiation have been shown to induce physiological changes in plants. The wild-type (Ler) Arabidopsis plants were irradiated with 100 Gy and 800 Gy of gamma-ray. Gibberellin (GA) affects developmental processes and responses according to the various environment conditions in diverse plant. The 13 GA isomers were analyzed at vegetative (VE) and reproductive (RE) stages by HPLC. Total GA contents were reduced with the increase in radiation doses at VE and RE stages. Specifically, levels of GA3, GA4, GA12, and GA34 were significantly reduced with the increase of radiation doses. Oligonucleotide microarrays analysis was performed with Arabidopsis plants at different developmental stages and doses of gamma-ray. Through the microarray data, we isolated 41 genes related to GA biosynthesis and signaling transduction. Expression of these genes was also decreased as the reduction of GA contents. Interestingly, in GA signaling related gene expression, gibberellin-responsive protein, putative (At2g18420) was down-regulated at VE and RE stages. Myb21 (At3g27810), Myb24 (At5g40350), and Myb57 (At3g01530) was down-regulated at RE stage. In GA biosynthesis related gene expression, YAP169 (At5g07200) and GA20ox2 (At5g51810) were down-regulated at 100 Gy treatment of VE stage and 800 Gy treatment of RE stage in cytoplasm, respectively. However, exceptively, GA3ox2 (At1g80340) was up-regulated at 100 Gy treatment of RE stage in cytoplasm. In this study, the wild type (Ler) Arabidopsis plants showed differences in response with development stage at the various doses of gamma-rays. GA contents change was reported in gamma irradiated plant.

• Korean Journal of Plant Resources
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• v.37 no.1
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• pp.79-86
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• 2024

This study was conducted to determine the conditions for breaking dormancy in the seeds of the North Korean plant resource, Trollius macropetalus, and to investigate its germination characteristics. The morphological characteristics and viability of T. macropetalus seeds were examined. Germination characteristics were investigated based on temperature conditions (15/6℃ & 25/15℃), cold stratification treatment, and GA₃ treatment. The results showed that cold stratification treatment had no effect on breaking the dormancy of T. macropetalus. GA₃ treatment significantly increased the germination rate of T. macropetalus and also improved the mean germination days and germination speed. However, compared to the 15/6℃ condition, the effectiveness of GA₃ treatment for T. macropetalus decreased under the 25/15℃ condition. It was determined that T. macropetalus have a nondeep-type morpho-physiological dormancy. The most effective conditions for breaking dormancy were found to be the 15/6℃ temperature condition and GA₃ treatment at 500 mg·L^-1. The findings of this study are expected to provide valuable information for the mass propagation of T. macropetalus, which has potential applications in landscaping and pharmaceutical materials.

• Journal of Powder Materials
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• v.25 no.6
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• pp.482-486
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• 2018

Despite numerous advances in the preparation and use of GaN, and many leading-edge applications in lighting technologies, the preparation of high-quality GaN powder remains a challenge. Ammonolytic preparations of polycrystalline GaN have been studied using various precursors, but all were time-consuming and required high temperatures. In this study, an efficient and low-temperature method to synthesize high-purity hexagonal GaN powder is developed using sub-micron $Ga_2O_3$ powder as a starting material. The sub-micron $Ga_2O_3$ powder was prepared by an ultrasonic spray pyrolysis process. The GaN powder is synthesized from the sub-micron $Ga_2O_3$ powder through a nitridation treatment in an $NH_3$ flow at $800^{\circ}C$. The characteristics of the synthesized powder are systematically examined by X-ray diffraction, scanning and transmission electron microscopy, and UV-vis spectrophotometer.