• KOREAN JOURNAL OF CROP SCIENCE
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• v.65 no.4
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• pp.377-385
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• 2020

Recently, wheat consumption has been increasing in Korea, requiring increased production. Nitrogen fertilization is a critical determinant in crop yield; therefore, it is necessary to optimize the nitrogen fertilization regime with current trends that emphasize the minimum impact of nitrogen fertilizer on the environment. In this study, both nondestructive spectral analysis using a hyperspectral camera and growth analysis were performed to determine the optimal N top-dressing rates after heading. The nitrogen application regimes consisted of three conditions according to the secondary top-dressing rate: N_4:3:0 (0 kg 10 a^-1), N_4:3:3 (2.73 kg 10 a^-1), and N_4:3:6 (5.46 kg 10 a^-1). Subsequently, growth and physiological investigations were performed at the jointing, heading, and ripening stages of wheat, and spectral investigations were conducted. On April 29, as the nitrogen fertilization rate was increased to N_4:3:3 and N_4:3:6, plant height and grain yield increased by 4% and 8%, and 8% and 52%, respectively, compared to those under N_4:3:0. Leaf area index and SPAD value also increased by 13% and 24%, and 32% and 43%, respectively. The R (red), G (green), and B (blue) of leaf color were lowered by 15, 11, and 4 in N_4:3:3 and 44, 34, and 18 in N_4:3:6, respectively, as compared to the control. Grain yield was the highest at high top-dressing (N_4:3:6), however, there was no difference between no top-dressing (N_4:3:0) and intermediat top-dressing (N_4:3:3). The reflectance analyzed using a hyperspectral camera showed a difference in the near-infrared (NIR) region on March 19, and on April 29, there was a difference both in the visible light region greater than 550 nm and the NIR region. Vegetation indices differed according to fertilization regime, except for the greenness index (GI). The results of this study showed that not only growth and physiological analysis but also spectral indices can be used to optimize the nitrogen top-dressing rate.

• Korean Journal of Ecology and Environment
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• v.40 no.1
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• pp.14-30
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• 2007

The purpose of this study was to evaluate trophic conditions of various Korean reservoirs using Trophic State Index (TSI) and predict the reservoir conditions by empirical models. The water quality dataset (2000, 2001) used here were obtained from the Ministry of Environment, Korea. The water quality, based on multi-parameters of dissolved oxygen (DO), biological oxygen demand (BOD), chemical oxygen demand (COD), total phosphorus (TP), total nitrogen (TN), suspended solid (SS), Secchi depth (SD), chlorophyll-${\alpha}$ (CHL), and conductivity largely varied depending on the sampling watersheds and seasons. In general, trophic conditions declined along the longitudinal axis of headwater-to-the dam and the largest seasonal variations occurred during the summer monsoon of July-August. Major inputs of TP occurred during the monsoon (r=0.656, p=0.002) and this pattern was similar to solid dynamics of SS (r=0.678, p<0.001). Trophic parameters including CHL, TP, SD, and TN were employed to evaluate how the water systems varies with season. Trophic State Index (TSI, Carlson, 1977), based on TSI (CHL), TSI (TP), and TSI (SD), ranged from mesotrophic to eutrophic. However, the trophic state, based on TSI (TN), indicated eutrophic-hypereutrophic conditions in the entire reservoirs, regardless of the seasons, indicating a N-rich system. Overall, nutrient data showed that phosphorus was a primary factor regulating the trophic state. The relationships between CHL (eutrophication index) vs. trophic parameters (TN, TP, and SD) were analysed to develop empirical models which can predict the trophic status. Regression analyses of log-transformed seasonal CHL against TP showed that the value of $R^2$ was 0.31 (p=0.017) in the premonsoon but was 0.69 (p<0.001) during the postmonsoon, indicating a greater algal response to the phosphorus during the postmonsoon. In contrast, SD had reverse relation with TP, CHL during all season. TN had weak relations with CHL during all seasons. Overall, data suggest that TP seems to be a good predictor for algal biomass, estimated by CHL, as shown in the empirical models.

• Korean Journal of Veterinary Research
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• v.41 no.4
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• pp.571-578
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• 2001

To evaluate if the apoptotic fragment assay could be used to estimate the dose prediction after radiation exposure, we examined apoptotic mouse crypt cells per 1,000 cells after whole body $^{60}Co$ $\gamma$-rays and 50MeV ($p{\rightarrow}Be^+$) cyclotron fast neutron irradiation in the range of 0.25 to 1 Gy, respectively. The incidence of apoptotic cell death rose steeply at very low doses up to 1 Gy, and radiation at all doses tigger rapid changes in crypt cells in stem cell region. These data suggest that apoptosis may play an important role in homeostasis of damaged radiosensitive target organ by removing damaged cells. The curve of dose-effect relationship for the data of apoptotic fragments was obtained by the linear-quadratic model $y=0.18+(9.728{\pm}0.887)D+(-4.727{\pm}1.033)D^2$ ($r^2=0.984$) after $\gamma$-rays irradiation, while $y=0.18+(5.125{\pm}0.601)D+(-2.652{\pm}0.7000)D^2$ ($r^2=0.970$) after neutrons in mice. The dose-response curves were linear-quadratic, and a significant dose-response relationship was found between the frequency of apoptotic cell and dose. These data show a trend towards increase of the numbers of apoptotic crypt cells with increasing dose. Both the time course and the radiation dose-response curve for high and low linear energy transfer (LET) radiation modalities were similar. The relative biological effectiveness (RBE) value for crypt cells was 2.072. In addition, there were significant peaks on apoptosis induction at 4 and 6h after irradiation, and the morpholoigcal findings of the irradiated groups were typical apoptotic fragments in crypt cells that were hardly observed in the control group. Thus, apoptosis in crypt cells could be a useful in vivo model for studying radio-protective drug sensitivity or screening test, microdosimetric indicator and radiation-induced target organ injury. Since the apoptotic fragment assay is simple, rapid and reproducible in the range of 0.25 to 1 Gy, it will also be a good tool for evaluating the dose response of radiation-induced organ damage in vivo and provide a potentially valuable biodosimetry for the early dose prediction after accidental exposure.

• Korean Journal of Ecology and Environment
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• v.39 no.3 s.117
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• pp.340-351
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• 2006

To reveal physicochemical factors contributing to variation of phytoplankton communities, the study was carried out biweekly at 6 stations from Feb. 2004 to Feb. 2005 in the lower part of the Han River, Korea. As results, water temperature was changed from $0.3^{\circ}C$ to $26.6^{\circ}C$, pH: 6.6${\sim}$9.1, DO: 1.89${\sim}$22.23 mg $L^{-1}$, BOD: 0.38${\sim}$9.20 mg $L^{-1}$, COD: 1.4${\sim}$15.2 mg $L^{-1}$, Conductivity: $62.5{\sim}500.0\;{\mu}s\;cm^{-1}$, SS: 3.00${\sim}$159.3 mg $L^{-1}$, and Chl a $1.7{\sim}71.3\;{\mu}g\;L^{-1}$. Phytoplankton standing crops ranged from min. $3.6{\times}10^2\;cells\;mL^{-1}$ (July 2004, St. 3) to max. $2.3{\times}10^4\;cells\;mL^{-1}$ (Feb. 2005, St. 6), and mean of those varied from $5.9{\times}10^3\;cells\;mL^{-1}$in spring, $2.1{\times}10^3\;cells\;mL^{-1}$ in summer, $4.1{\times}10^3\;cells\;mL^{-1}$ in autumn and $8.5{\times}10^3\;cells\;mL^{-1}$ in winter, respectively. In order to investigate factors influencing the total phytoplankton standing crops a multiple regression analysis was adopted for the correlation between standing crops and environmental factors. The coefficient of determination ($R^2$) value of the regression was 0.465, it showed that environmental factors which predominantly influenced phytoplankton standing crops were water temperature, COD, $NO_2-N$, $PO_4-N$, Discharge and pH. six stations could be divided into 3 groups based on similarity index in terms of environmental factors. In ANOVA analysis for physicochemical and biological factors, water temperature, chlorophyll a, silicate, phytoplankton standing crops were the same group differed little from stations. However, Station 1and 2 were grouped followed in dissolved oxygen, conductivity, COD, nitrite, nitrate, ammonia and phosphate, and Station 3, 4 and 5 were followed in dissolved oxygen, conductivity, pH and phosphate.

• Journal of the Korean Society of Food Science and Nutrition
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• v.40 no.10
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• pp.1397-1403
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• 2011

Epimedium koreanum Nakai is a wild medicinal plant commonly consumed in South Korea due to its health beneficial effects. In the present study, the antioxidative, antimutagenic and immunological activities of E. koreanum Nakai extracts were investigated for their use in food. The yields of icariin compounds from the ethanol extract as well as the ethyl acetate, butanol, hexane, water, and chloroform fractions of E. koreanum were 27.9, 2.5, 1.7, 1.4, and 1.3 ${\mu}g/g$, respectively. The icariin components (295.5 ${\mu}g/g$) were collected from the ethyl acetate fraction by thin layer chromatography (TLC) and analyzed via high performance liquid chromatography (HPLC). The antioxidant activities of each fraction were as follows: ethyl acetate (49.0 ${\mu}g/mL$), butanol (59.2 ${\mu}g/mL$), hexane (119.8 ${\mu}g/mL$), water (122.0 ${\mu}g/mL$), and chloroform (138.5 ${\mu}g/mL$), based on $RC_{50}$ ${\mu}g/mL$. Icariin, isolated and identified as the main component, showed strong antioxidant activity with a $RC_{50}$ value of 15.3 ${\mu}g/mL$, which was higher than those of ascorbic acid (19.5 ${\mu}g/mL$) and ${\alpha}$-tocopherol (18.2 ${\mu}g/mL$). In an Ames test, none of the fractions produced mutagenic effects on Salmonella Typhimurium TA98 and TA100. In an immunomodulating activity test, the effects of E. koreanum Nakai on B cells (Rhamos) and T cells (Jurkat) were investigated. These results show that the growth and viability of B and T cells were increased by isolated icariin components for 1.27 and 1.28 fold, respectively. These results also provide preliminary data for the development of E. koreanum Nakai as an edible food material.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.34 no.5
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• pp.445-456
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• 2001

In the 1990s, Cochlodinium polykikoides red tide has been annually occurred in the southern coast of Korea and caused the mass damage to the fisheries with a huge amount of economic loss. The present study was done to establish the biological foundation for the elucidation of the mechanism of C. polykikoiaes red tide. The growth response of C. polykikoides to physico-chemical factors such as temperature, salinity, pH, and light intensity were examined using axenic cultures to evaluate the relative importance of these factors on the dynamics of natural populations, It was found that the highest growth conditions were $25^{\circ}C,\;40\%_{\circ}$, pH 7.5, and 7,500 lux, respectively. The tolerable salinity range of growth was relatively wide at an optimum temperature and was reduced to a much narrower range at a sub-optimum temperature. These findings indicate that C. polykikoides is an eurythermal and euryhaline organism. The organism demanded higher light intensity and oceanic pH narrow in its growth. C. polykikoides utilize inorganic nutrients, such as nitrate and ammonium as N, and phosphate as P. The nutritional requirements of C. polykikoides were $40{\mu}M$ for nitrate, $50{\mu}M$ for ammonium, and $5{\mu}M$ for phosphate. The half saturation constant (Ks) for growth was $2.10{\mu}M$ for nitrate, $1.03{\mu}M$ for ammonium, and $0.57{\mu}M$ for phosphate. These values were comparatively smaller than those of other dinoflagellates reported previously. We confirmed that the organism is characterized as an eutrophic species. However, ammonium Ks value is smaller than that of other eutrophic species, This result indicates that C. polykikoides red tide may outbreak in the waters which eutrophication is in progress rather than eutrophicated waters. C. polykikoides preferred ammonium better than nitrate as a nitrogen source when in a growth stage, Therefore, our results indicate that ammonium is more important nutrient on the growth of the organism in comparison with other inorganic nutrients and C. polykikoides red tide is related with the increased ammonium concentration in the coastal waters.

• Journal of the Korean Institute of Landscape Architecture
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• v.42 no.1
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• pp.104-114
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• 2014

Nowadays, forests have been recognized as valuable resources for biological diversity and tourism/recreation. Temple forests occupy 1.3% of all the Korean forest and are under weak management although their ecological states are very good. Currently in the Buddhist society, the concern for the Buddhist arboretum has been raised as a good alternative for the practical use of temple forests to secure the sustainability of the temple forests as well as to actively meet the demand of the times for forests. This study aims to suggest establishment measures of Buddhist arboretum. This survey was performed on 105 temple forest managers and 130 laypersons. To summarize the results, the two groups differ in opinion. The temple forest managers more concerned for advertizing Buddhist culture and enhancing the image of the temple, while the laypersons had higher expectations for relaxation and education. However, they are similar in putting more emphasis on the conserving the heritage value of the temple and managing the temple forest. Above all, both groups evaluated the needs higher than the urgency and perceived managing temple forest as the most crucial function of a Buddhist arboretum. They also thought that a Buddhist arboretum should be planned to respond to the ecological characteristics of the temple area as well as to be non-exclusive to its users. Based on the important findings, five suggestions for a Buddhist arboretum were proposed. First, a Buddhist arboretum should be carried forward from a long-term point of view, developing a bond of sympathy between members of Buddhist society as well as conducting promotion and education to the general public. Second, the most significant function of a Buddhist arboretum should be preserving the temple forest, with the emphasis on relaxation and education. Third, in order to provide nonexclusive use, a Buddhist arboretum should provide mixed programs applicable to diverse user groups for high user satisfaction and educational effects. Fourth, the Buddhistic identification could be obtained through variety of plants closely associated with Buddhist culture. Lastly, in the process of collecting plants, it is also crucial to reflect the image of the temple and resource property so as to contribute itself in conservation and management of original temple forests. Thereby all Buddhist Arboretum can be classified into two types; preservation/collection and display/education/rest.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.4
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• pp.610-613
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• 2012

Oyster shell has a high content of $CaCO_3$ to be used as a acidic soil amendment. To enhance productivity of barley and soil microbe in an upland soil, oyster shell and calcium-magnesium carbonate were selected as a soil amendments in this study. A field experiment was treated no treatment (hereafter, control), oyster shell lime $3.09Mg\;ha^{-1}$ and $2.38Mg\;ha^{-1}$, and calcium-magnesium carbonate $2.38Mg\;ha^{-1}$ as amount of lime requirement in silt loam soil. The yield of barley from the oyster shell lime treatment was the highest. The protein content of barley was the highest of 11.1% in the calcium-magnesium carbonate, followed by 10.7% for the control, 10.6% for the oyster shell lime $3.09Mg\;ha^{-1}$, and 10.4% for the oyster shell lime $2.38Mg\;ha^{-1}$. Soil pH value was higher than that of control in harvesting stage. In addition, the population of soil bacteria was highest in oyster shell lime $2.38Mg\;ha^{-1}$, actinomycetes was highest in calcium-magnesium $2.38Mg\;ha^{-1}$. We concluded that the oyster shell lime can be effective to restore soil nutrient and microbe balance in an upland soil.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.65 no.2
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• pp.113-123
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• 2020

Global climatic change and increasing climatic instability threaten crop productivity. Due to climatic change, drought stress is occurring more frequently in crop fields. In this study, we investigated the effect of treatment with hydrogen peroxide (H₂O₂) before leaf development on the growth and yield of sorghum for minimizing the damage of crops to drought. To assess the effect of H₂O₂ on the growth of sorghum plant, 10 mM H₂O₂ was used to treat sorghum leaves at the 3-leaf stage during growth in field conditions. Plant height, stem diameter, leaf length, and leaf width were increased by 7.6%, 9.6%, 8.3% and 11.5%, respectively. SPAD value, chlorophyll fluorescence (Fv/Fm), photosynthetic rate, stomatal conductance, and transpiration rate were increased by 3.0%, 4.9%, 26.0%, 23.4% and 12.7%, respectively. The amount of H₂O₂ in the leaf tissue of sorghum plant treated with 10 mM H₂O₂ was 0.7% of the applied amount after 1 hour. The level increased to approximately 1.0% after 6 hours. The highest antioxidant activity measured by the Oxygen Radical Absorbance Capacity assay was 847.3 µmol·g^-1 at 6 hour after treatment. However, in the well-watered condition, the concentration of H₂O₂ in the plant treated by the foliar application of H₂O₂ was 227.8 µmol·g^-1 higher than that of the untreated control. H₂O₂ treatment improved all the yield components and yield-related factors. Panicle length, plant dry weight, panicle weight, seed weight per plant, seed weight per unit area, and thousand seed weight were increased by 8.8%, 18.0%, 24.4%, 24.7%, 29.9% and 7.1%, respectively. Proteomic analysis showed that H₂O₂ treatment in sorghum increased the tolerance to drought stress and maintained growth and yield by ameliorating oxidative stress.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.7
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• pp.432-440
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• 2015

Biochar, a by-product from pyrolysis of biomass, is a promising option to mitigate climate change by increasing soil carbon sequestration. This material is also considered to have potential to remediate a soil with heavy metal pollution by increasing the soil's adsorptive capacity. This study conducted the assessment of two biochars considering the climate change mitigation potential and heavy metal removal capacity at the same time. Two kinds of biochars (BC_Ch, TW_Ch) were prepared by pyrolyzing the biomass of burcucumber (BC_Bm) and tea waste (TW_Bm). The soils polluted with Pb were mixed with biochars or biomass and incubated for 60 d. During the incubation, $CO_2$, $CH_4$, and $N_2O$ were regularly measured and the soil before and after incubation was analyzed for chemical and biological parameters including the acetate extractable Pb. The results showed that only the BC_Ch treatment significantly reduced the amount of Pb after 60 d incubation. During the incubation, the $CO_2$ and $N_2O$ emissions from the BC_Ch and TW_Ch were decreased by 24% and 34% compared to the BC_Bm and TW_Bm, respectively. The $CH_4$ emissions were not significantly affected by biochar treatments. We calculated the GWP considering the production of amendment materials, application to the soils, removal of Pb, and soil carbon storage. The BC_Ch treatment had the most negative value because it had the higher Pb adsorption and soil carbon sequestration. Our results imply that if we apply biochar made from burcucumber, we could expect the pollution reduction and climate change mitigation at the same time.