• Horticultural Science & Technology
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• v.35 no.2
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• pp.252-264
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• 2017

Tea is one of the most consumed beverages worldwide and the relatively high levels polyphenols is benefit for health. In this study, we developed an efficient system for proliferation of callus from 'Anji Baicha', a cultivar of tea (Camellia sinensis). Callus tissue was initially induced by culturing leaf explants on medium containing different plant growth regulators. For callus induction, thidiazuron (TDZ) was more effective than 2,4-dichlorophenoxyacetic acid (2,4-D), ${\alpha}-naphthalene$ acetic acid (NAA), and $N^6-benzyladenine$ (BA). The frequency of callus induction from leaf explants reached 90.21% on $1.0mg{\cdot}L^{-1}$ TDZ and the developed callus was reddish and friable. We also tested the effect of different concentrations of NAA, 2,4-D, indole 3-acetic acid (IAA), BA, and TDZ, alone and in combinations, on callus proliferation. Medium supplemented with TDZ in combination with IAA was suitable for callus proliferation and accumulation of tea polyphenols. The growth index value and tea polyphenol content of callus cultured on MS medium containing $0.5mg{\cdot}L^{-1}$ TDZ and $1.0mg{\cdot}L^{-1}$ IAA was maximally 1,351% and 23.24%, respectively, and the relative abundance of epicatechin was as high as 17.449%. We also measured the antioxidant activity of all samples and the callus with the highest tea polyphenol content also exhibited high potential radical scavenging activity.

• Korean Journal of Soil Science and Fertilizer
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• v.32 no.2
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• pp.132-139
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• 1999

A field experiment was conducted at Cheju from early March 1998 to early March 1999 to evaluate the effects of foliar applied urea on leaf N content and N recovery in satsuma mandarins (Citrus unshiu Marc.). Seven years old 'Okitsu Wase' trees received foliar spray of urea (22 or 43 g N $tree^{-1}yr^{-1}$) or soil application of urea (86 g N $tree^{-1}yr^{-1}$). 56% of N was applied in spring, 11% in summer and 33% in fall. There were seven trees per N treatment and two trees per N treatment received $^{15}N$-labeled urea in spring and summer to determine N recovery. There were no differences between the treatments for fruit yield and its quality. Nitrogen content of spring flush leaf blades up to early September was greater for trees received foliar spray comparing with soil application but was not greatly affected by any treatment after mid-November. The recovery of fertilizer N in various parts of trees receiving foliar spray of 22 g N $tree^{-1}yr^{-1}$ was greatest, followed by receiving foliar spray of 43 g N and soil application of 86 g N. The recovery of fertilizer N in tree was 29.2 and 17.7% for foliar spray of 22 and 43 g N $tree^{-1}yr^{-1}$, respectively and 8.0% for soil application of 86 g N $tree^{-1}yr^{-1}$. The recovery of fertilizer N in the upper 40 cm of soil was 50.3, 45.6, and 51.8% for foliar spray of 22 and 43 g N $tree^{-1}yr^{-1}$, and soil application of 86 g N $tree^{-1}yr^{-1}$ respectively. The total (tree, fallen leaves, winter weeds, and soil) recovery of fertilizer N was 81.8, 65.1, and 60.6% for foliar spray of 22 and 43 g N $tree^{-1}yr^{-1}$, and soil application of 86 g N $tree^{-1}yr^{-1}$, respectively.

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.3
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• pp.349-355
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• 2010

This experiment was conducted to establish the optimum nitrogen application level for oriental melon at Seong-ju Fruit Vegetable Experiment Station with a fertigation system. Four different levels of nitrogen fertigation were applied to oriental melon and growth of the plant was analyzed. Plant samples were collected 8 times and were analyzed by the standard methods. The first fertigation was applied at 10 days after transplanting for the oriental melon based on the growth rates of the plants. For oriental melon, 10 day interval fertigation and 8 time split application of fertilizer could be recommended. The amounts of N, P, and K fertilizer recommended by soil testing was 249-408-315 (kg $ha^{-1}$). Treatment levels were 0, 0.5, 1.0, and 1.5 times of soil testing nitrogen with P and K level fixed. The total nitrogen (T-N) content in dried leaf showed a tendency to increase until 30 days after transplanting, then decreased. T-N content increased with increasing nitrogen fertigation rates. T-N content in dried fruit decreased slightly during the whole growing season. Fresh weight and nitrogen uptake were increased with increasing nitrogen fertigation rates. Total yield and marketable yield, 44,550 kg $ha^{-1}$ and 42,880 kg $ha^{-1}$, were maximized at 0.5 times of soil test nitrogen. Ratio of marketable fruit, 95%, was the highest at 0.5 times of soil test nitrogen. The optimum level of nitrogen for fertigation system was 0.5 times soil test nitrogen judging from total yield, commodity yield and commodity fruit.

• Korean Journal of Soil Science and Fertilizer
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• v.27 no.3
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• pp.209-214
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• 1994

A study was conducted to study yield response and nutrient uptakes with N, P, K application. Its growth and root yield of Aralia continentalis was increased along with the added amount of fertilizer, and optimum fertilization rates of N, P, K were 38, 21, 18kg/10a, respectively. On the path coefficient analysis between the growth characters and root yield, its values showed in the order of plant height, root width, number of budstocks, number of branch, stem width and number of root. Relative yield of non-fertilization against fertilization of N, P, K were low in the order of N, P and K, that is, responses of fertilization on root yield of Aralia continentalis were affected greatly in the order of N, K and P, but the fertilization efficiency was high in the order of K, P and N. Calcium content was the highest and phosphorus content was the lowest among the mineral nutrients contained in the leaf, but relationships between nitrogen content and root yield was showed positive correlation the difference distinctly between the chemicals and the organics.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.27 no.1
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• pp.66-71
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• 1982

Field experiments of nitrogen application (0, 100, 200, 400, 800kg N/ha year) were carried out to study the nitrogen response of Sudangrass at College Farm, Seoul National Univ., in 1979 and 1980. Dry matter yield and leaf area index increased up to 400kg N/ha in 1979 and 800kg N/ha in 1980. The forage yield of 1980 was less than that of 1979, due to the extraordinarily low temperature and the decreased solar radiation during summer. Total nitrogen contents in forage increased with nitrogen application, but maximum contents were found either 400 or 800kg N levels depend on each cutting stages. Nitrate nitrogen content in forage exceded over 2000 ppm at 800kg N application. Overall percentages of N recovery were below 50% with average 34%. Net assimilation rate and nitrogen use efficiency of Sudangrass were improved in higher temperature and more sunlight condition during regrowth period.

• Journal of Ecology and Environment
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• v.47 no.3
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• pp.85-102
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• 2023

Background: Ecophysiological characteristics of Rosa rugosa were analyzed under different environmental factors from May to October 2022. Photosynthesis, chlorophyll fluorescence, chlorophyll content, leaf water content (LWC), osmolality, carbohydrate content, and total ion content were measured to compare the physiological characteristics of R. rugosa at two study sites (i.e., in large pots and in the Goraebul coastal sand dune area). Results: When R. rugosa was exposed to high temperatures, photosynthetic parameters including net photosynthetic rate (P_N) and stomatal conductance (g_s) in both experiment areas declined. In addition, severe photoinhibition occurs when R. rugosa is continuously exposed to high photosynthetically active radiation (PAR), and because of this, relatively low Y(II) (i.e., the quantum yield of photochemical energy conversion in photosystem II [PSII]) and high Y(NO) (i.e., the quantum yield of non-regulated, non-photochemical energy loss in PSII) in the R. rugosa of the pot were observed. As the high Y(NPQ) (i.e., the quantum yield of regulated non-photochemical energy loss in PSII) of R. rugosa in the coastal sand dune, they dissipated the excessed photon energy through the non-photochemical quenching (NPQ) mechanism when they were exposed to relatively low PAR and low temperature. Rosa rugosa in the coastal sand dune has higher chlorophyll a and carotenoid content. The high chlorophyll a + b and low chlorophyll a/b ratios seemed to optimize light absorption in response to low PAR. High carotenoid content played an important role in NPQ. As a part of the osmotic regulation in response to low LWCs, R. rugosa exposed to high temperatures and continuously high PAR used soluble carbohydrates and ions to maintain high osmolality. Conclusions: We found that F_v/F_m was lower in the potted plants than in the coastal sand dune plants, indicating the vulnerability of R. rugosa to high temperatures and PAR levels. We expect that the suitable habitat range for R. rugosa will shrink and move to north under climate change conditions.

• Journal of Plant Biotechnology
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• v.41 no.2
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• pp.100-106
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• 2014

In order to develop an efficient in vitro micropropagation technique for a rare plant species, Astragalus membranaceus Bunge var. alpinus N., shoot proliferation and in vitro or in vivo rootings were conducted and hyperhydrated leaf generated from cultures was histologically observed. During shoot induction, no distinct effect on multiple shoot induction was found between BA and kinetin treatment. BA enhanced the number of internodes, whereas kinetin stimulated shoot elongation. Hyperhydrated leaf composed of bigger cells and retarded palisade parenchyma and showed irregular cell arrangement compared to normal leaf. Especially starch content in hyperhydrated leaf was significantly reduced. The best rooting rate was achieved by B5 medium among three different medium (B5, MS and WPM) and 0.1mg/L IBA treatment induced the highest rooting ratio (80%). No statistical difference was induced by explant types (apical bud or axillary bud) in terms of rooting ratio. In vivo cutting induced rooting rate up to 65% by 0.5% IBA/Talc powder treatment. Although in vivo rooting rate was less efficient compared to in vitro rooting, better survival rate was observed after soil acclimatization. Present study suggested that above micropropagation techniques can be used for rapid multiplication as well as in vitro or in vivo conservation of the species.

• Korean Journal of Organic Agriculture
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• v.10 no.4
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• pp.37-45
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• 2002

This study was conduction to investigate the effects of natural materials such as $GB_{10}$ chitofarm, chaff charcoal, and chaff charcoal sap, on quality and yield of chinese cabbage, Natural materials were treated on seeds soil, and leaves. The total plant weight, head weight, head length, head width, leaf length, leaf width, and sugar content of chinese cabbage in treatment with natural materials showed significant difference compared with control. The yield of chinese cabbage in $GB_{10}$ soil treatment and 1% $GB_{10}$ leaf treatment was increased 53% compared with control. The total nitrogen $P_2O_5$, $K_2O$, CaO, MgO, $Na_2O$, and Mn in total plant were analyzed. The chemical components were increased in total plant of chinese cabbage treated with natural materials compared with control natural materials increased the quality of chinese cabbage.

• Journal of the korean society of oceanography
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• v.38 no.2
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• pp.68-79
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• 2003

Although seagrasses are relatively abundant, few studies have been conducted on seagrass physiology and ecology in Korea. Zostera marina is the most abundant seagrass species, widely distributed throughout all coastal areas of the Korean peninsula. To examine seasonal dynamics and spatial variations of eelgrass, Zostera marina distributed on the coast of Korea, morphological characteristics, biomass, tissue nutrient constituents, leaf productivity and environmental factors were monitored monthly from the eelgrass beds in Kabae Bay and Kosung Bay on the south coast of the Korean peninsula from June 2001 to June 2002. Eelgrass density, biomass, morphological characteristics, leaf productivities, and tissue nutrient constituents exhibited clear seasonal variations, and these seasonal trends reflected seasonal changes in water temperature. Eelgrass shoot density and biomass at Kabae Bay site showed more obvious seasonal trends than Kosung Bay. No strong seasonality in Kosung Bay site appeared to be caused by high water temperature ($>30{\circ}C$) during summer months at this site. Despite differences in nutrient availabilities between two study sites, eelgrass biomass and leaf productivities were not significantly different between study sites, and this lack of spatial variations implies that the ambient nutrient availabilities at the present study sites are in excess of seagrass nutrient demand. Eelgrass tissue N content and sediment pore water DIN concentrations exhibited reverse relationship at the present study. This reverse relationship suggests in situ nutrient concentrations are not good indicator of nutrient availabilities, and regeneration and turnover rates of sediment nutrients are also important factors to determine nutrient availabilities at the site.

• Journal of Ecology and Environment
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• v.47 no.3
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• pp.103-116
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• 2023

Background: This study analyzed the physiological adaptations of a woody plant, Vitex rotundifolia, in Goraebul coastal sand dunes from May to September 2022. Environmental factors and physiological of plants growing under field and controlled (pot) conditions were compared. Results: Photosynthesis in plants growing in the coastal sand dunes and pots was the highest in June 2022 and July 2022, respectively. Chlorophyll fluorescence indicated the presence of stress in the coastal sand dune environment. The net photosynthesis rate (P_N) and Y(II) were highest in June in the coastal sand dune environment and July in the pot environment. In August and September, Y(NPQ) increased in the plants in the coastal sand dune environment, showing their photoprotective mechanism. Chlorophyll a and b contents in the pot plant leaves were higher than those in the coastal sand dune plant leaves; however, chlorophyll-a/b ratio was higher in the coastal sand dune plant leaves than in the pot plant leaves, suggesting a relatively high photosynthetic efficiency. Carotenoid content in the coastal sand dune plant leaves was higher in August and September 2022 than that in the pot plant leaves. Leaf water and soluble carbohydrate contents of the coastal sand dune plant leaves decreased in September 2022, leading to rapid leaf abscission. Diurnal variations in photosynthesis and chlorophyll fluorescence in both environments showed peak activity at 12:00 hour; however, the coastal sand dune plants had lower growth rates and Y(II) than the pot plants. Plants in the coastal sand dunes had higher leaf water and ion contents, indicating that they adapted to water stress through osmotic adjustments. However, plants growing in the coastal sand dunes exhibited reduced photosynthetic activity and accelerated decline due to seasonal temperature decreases. These findings demonstrate the adaptation mechanisms of V. rotundifolia to water stress, poor soils, and high temperature conditions in coastal sand dunes. Conclusions: The observed variations indicate the responses of the V. rotundifolia to environmental stress, and may reveal its survival strategies and adaptation mechanisms to stress. The results provide insights into the ecophysiological characteristics of V. rotundifolia and a basis for the conservation and restoration of damaged coastal sand dunes.