• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.19 no.1
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• pp.76-87
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• 2014

Chlorophyll a in seawater which is an indicator of phytoplankton biomass and primary production is determined by High Performance Liquid Chromatography (HPLC), Fluorometry and Spectrophotometry. In this study, various methods for chlorophyll a determination in seawater are compared using in situ seawater samples from Korean seas. Three inter-laboratory comparison campaigns were carried out using chlorophyll a standard samples (R0) and in situ seawater samples, collected from the East China Sea (R1) and the East Sea (R2). 6 laboratories by HPLC methods, 4 laboratories by fluorometry, and 3 laboratories by spectrophotometry participated. Precisions, defined as the coefficient of variation (CV) were within 9% in standard samples, 0.8~20% (average: 6.1%) in R1, 4~21% (average: 13.2%) in R2. Discrepancy in three methods was approximately 20% within the range of the sample homogeneity intended the laboratory precision (R1: 8%, R2: 15%). The discrepancy in laboratories was greater than the discrepancy in methods. The chlorophyll a concentrations can be produced within 20% discrepancy in spite of using different methods. It is recommended to consider this 20% discrepancy when using the chlorophyll a data produced by different laboratories and different methods.

• Korean Journal of Environment and Ecology
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• v.30 no.6
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• pp.1009-1021
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• 2016

The community structure and abundance of epilithic biofilm were bimonthly examined to know spatial and temporal patterns of biofilm biomass and taxonimical composition at the two study sites, Gosapo and Gyeokpo with different degrees of wave exposure levels from November 2010 to September 2011. Biomass was estimated by using chlorophyll a contents (Chl a), normalized difference vegetation index (NDVI), and vegetation index (VI). Cyanobacteria such as Aphanotece spp. predominated in the proportion of 57.53% at Gosapo and of 61.12% at Gyeokpo and they are abundant in mid shore and in summer at both study sites. The diatoms Navicula spp., Achnanthes spp. and Licmophora spp. were common species and they showed an increasing trend from high to low shore. NDVI, VI, and chl a contents were the greatest at mid shore for Gosapo (0.44, 3.05, $24.56{\mu}g/cm^2$) and at low shore for Gyeokpo (0.41, 2.73, $17.98{\mu}g/cm^2$). NDVI, VI, and chl a content were all maximal in January and minimal in March at the both sites. Average NDVI, VI, and chlorophyll a contents of biofilms were greater at Gosapo (0.43, 2.89, $22.84{\mu}g/cm^2$) than Gyeokpo (0.38, 2.48, $15.48{\mu}g/cm^2$).Of three shore levels(high, mid, and low) Chl a contents were positively correlated with NDVI and VI at the two study sites indicating that non-destructive NDVI and VI values can be used in stead of destructive Chl a extraction method. In conclusion, epilithic biofilm was more abundant seasonally in winter, vertically in mid and low intertidal zone, and horizontally at wave exposed shore than in summer, at high and sheltered shore in Korea.

• Korean Journal of Agricultural and Forest Meteorology
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• v.8 no.2
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• pp.61-67
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• 2006

We examined seedlings of two species (Ilex rotunda and Illicium anisatum) which have a different level of shade tolerance and raised them under different light regimes (full sunlight and 50% shading). After 12 months, we investigated chlorophyll content (Chl. a, Chl. b and Chl. a+b), photosynthetic systems (photosynthetic rate, light compensation point, dark respiration rate and quantum yield), intercellular $CO_2$ concentration and water use efficiency to show acclimation reaction to different light conditions. Seedlings grown under full sunlight showed lower chlorophyll content than those in the shading regime. There was a significant difference between the full sunlight and shade treatments in I. anisatum (shade tolerance species). I. rotunda (intermediate species) showed high photosynthetic rate and water use efficiency over PPFD $1000\;{\mu}mol\;m^{-2}s^{-1}$ to full sunlight. Also, I. anisatum grown under full sunlight showed lower photosynthetic rate and water use efficiency over a range of all PPFD. This result showed that I. rotunda has a more flexible reaction system than that of I. anisatum.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2000.07a
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• pp.287-292
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• 2000

• Horticultural Science & Technology
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• v.19 no.4
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• pp.555-559
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• 2001

This research was conducted to estimate the chlorophyll contents of chrysanthemum leaves using SPAD-502 chlorophyll meter under different photoperiod and light intensity. Measurements were done at every third leaf intervals starting from the top of the stem to the bottom at harvest time. SPAD value was highest at 10 hours of photoperiods, followed by 13 and 16 hours of photoperiods. In particular, under short day condition, SPAD value was highest in the young leaves below the flower bud and decreased down the leaf profile. Under long day condition, SPAD value reached maximum at leaves between $15-27^{th}$ from the top and decreased to the minimum immediately below the flower bud (youngest leaf). These results may indicate that the younger leaves become strong source of supporting flowers in reproductive stage, while the younger leaves serve as sinks and older leaves support their development in vegetative stage. Changes of SPAD value at different levels of irradiance showed that highest SPAD value were observed at high irradiance and decreased with decreasing irradiance.

• Korean Journal of Agricultural and Forest Meteorology
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• v.10 no.4
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• pp.141-148
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• 2008

This study was conducted to investigate the photosynthetic responses of four Oak species (Quercus mongolica, Q. serrata, Q. acutissima and Q. variabilis) by shading treatment. We investigated light response curve, photosynthesis (A)-intercellular $CO_2$ concentration (Ci) curve, leaf growth and chlorophyll content at the level of 35, 55 and 75% shading treatments and under the full sunlight. In our results, Q. variabilis and Q. acutissima showed increased leaf growth, chlorophyll content and net apparent quantum yield but reduced chlorophyll a/b and carboxylation efficiency under the low light intensity. Therefore, light absorption and light utilization efficiency were improved under the low light intensity. Q. mongolica showed the similar responses that Q. variabilis and Q. acutissima showed, but net apparent quantum yield was reduced. The effects of shading treatment on Q. serrata were lower than those of other three species.

• FLOWER RESEARCH JOURNAL
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• v.17 no.4
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• pp.237-241
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• 2009

This study was conducted to determine injury symptoms of orchids by sulfur dioxide gases, three orchid plants (Phalaenopsis, Cymbidium, Oncidium) were exposed to sulfur dioxide gas in an enclosed growth chambers. Sulfur dioxide gases treatments consist of five different concentrations (0, 5, 10 25, and 50 ppm) and plant exposure of 18 hours with $25{\pm}5^{\circ}C$ air temperature and $50{\pm}5%$ relative humidity. SPAD values for chlorophyll content and percent leaf injury as well as leaf ion exudation were measured before and after the gas treatments. Phalaenopsis leaves showed 23.3% leaf injury at 10 ppm sulfur dioxide gas, whereas Cymbidium and Oncidium showed 4.0 and 4.4% leaf injury under 25 ppm or less, respectively. Major leaf injury symptoms appeared as initial water-soaking under side of the leaf, followed by rapidly progressed complete leaf discolorization or chlorosis. As the gas concentration increased, the SPAD value decreased while ion exudation increased. Cymbidium and Oncidium were resistant to sulfur dioxide gas than Phalaenopsis.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.31 no.2
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• pp.226-230
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• 1986

Two near-isogenic lines with dark and pale green leaves, derived from the F$\_$7/ generation of wxl26 cross were compared on photosynthetic capacity, growth parameters, grain yield and yield-related characters. Dark green-leaved lines contained much greater content of chlorophyll a and b than pale green-leaved ones, but chlorophyll a to b ratio showed no difference between them. The photosynthetic nte per unit leaf area was higher in dark green-leaved lines than in pale green-leaved ones in the flag leaves at heading stage, but that per unit chlorophyll content showed reversed result. The crop growth rate from transplanting to heading was consistantly higher in the dark green-leaved lines, resulting from their greater net assimilation rate. Dark green-leaved lines produced greater number of panicles and spikelets per hill, out yielding pale green-leaved lines, but ripened grain ratio and 1000-grain weight showed no differences between those lines.

• Korean Journal of Environmental Biology
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• v.36 no.2
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• pp.156-164
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• 2018

In order to investigate the upwelling and island effects following the wind storm events in the East Sea (i.e., Uljin-Ulleungdo-Dokdo line) during spring, we assessed the vertical and horizontal profiles of abiotic and biotic factors, including phytoplankton communities. The assessment was based on the Geostationary Ocean Color Imager (GOCI) and field survey data. A strong south wind occurred on May 3, when the lowest sea level pressure (987.3 hPa) in 2016 was observed. Interestingly, after this event, huge blooms of phytoplankton were observed on May 12 along the East Korean Warm Current (EKWC), including the in the offshore waters of Ulleungdo and Dokdo. Although the diatoms dominated the EKWC area between the Uljin coastal waters and Ulleungdo, the population density of raphidophytes Heterosigma akashiwo was high in the offshore waters of Ulleungdo-Dokdo. Based on the vertical profiles of Chlorophyll-a (Chl. a), the sub-surface Chl. a maximum appeared at 20 m depths between Uljin and Ulluengdo, whereas relatively high Chl. a was distributed equally across the entire water column around the waters of Ulleungdo and Dokdo islands. This implies that the water mixing (i.e., upwelling) at the two islands, that occurred after the strong wind event, may have brought the rapid proliferation of autotrophic algae, with nutrient input, to the euphotic layer. Therefore, we have demonstrated that a strong south wind caused the upwelling event around the south-eastern Korean peninsula, which is one of the most important role in occurring the spring phytoplankton blooms along the EKWC. In addition, the phytoplankton blooms may have potentially influenced the oligotrophic waters with discrete time lags in the vicinity of Ulleungdo and Dokdo. This indicates that the phytoplankton community structure in the offshore waters of Ulleungdo-Dokdo is dependent upon the complicated water masses moving related to meandering of the EKWC.

• Horticultural Science & Technology
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• v.28 no.4
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• pp.600-608
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• 2010

The quality attributes of tomato fruit ($Lycopersicon$ $Esculentum$ Mill.) to treatments with 1-methylcyclopropene (1-MCP) were studied. Harvested tomato fruit was treated one time at the initiation of storage or once-a-day during storage with $1{\mu}L/L$ 1-MCP at different storage temperatures, 12, 17, and $23^{\circ}C$. The results showed that both lower temperature and duration of 1-MCP treatment played an important role in ripening of tomato fruit. The once-a-day 1-MCP treatment was presented to be very effective in delaying quality changes of tomato fruit. The amount of chlorophyll and lycopene were measured to assess the impact of 1-MCP and temperature treatments on ripening, using a specific extinction coefficient absorbance technique. Storing tomato fruit at $12^{\circ}C$ resulted in a longer ripening period (color change) than tomato fruit stored at $17^{\circ}C$ and $23^{\circ}C$. 1-MCP treatment was very effective in retarding chlorophyll degradation and lycopene formation in the pericarp tissue of the tomato fruit at the different storage temperatures. The 1-MCP treatments affected the total chlorophyll content in different fruit tissues of the pericarp and placenta. Exposure of tomato fruit to 1-MCP gas at $12^{\circ}C$, using the once-a-day treatment, was highly effective in delaying pigment and color change.