• KSBB Journal
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• v.6 no.2
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• pp.181-187
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• 1991

Physiological and morphological characteristics of Anabaena azollae cells immobilized in a synthetic polymer, polyvinyl(PV), were investigated. The cell density of the non-immersed PV foam reached 4.4mg Chl/g dry wt. PV foam. This is 8 times higher than that of PV-immobiliz action in immersed batch system. And MSX-induced ammonia productivity and the photosynthectic oxygen evolution activity are higher than that of free cells after short-term dark storage. Nitrogenase activity and thermostability of photosynthetic activity are also higher than that of free Anabaena cells after immobilization. Total hydrogen production reached to 1.6ml $H_2$ per reactor (total 4mg Chl) after 6 days.

• Journal of Microbiology and Biotechnology
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• v.32 no.11
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• pp.1357-1372
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• 2022

Heavy reliance on fossil fuels has been associated with increased climate disasters. As an alternative, microalgae have been proposed as an effective agent for biomass production. Several advantages of microalgae include faster growth, usage of non-arable land, recovery of nutrients from wastewater, efficient CO₂ capture, and high amount of biomolecules that are valuable for humans. Microalgae Chlorella spp. are a large group of eukaryotic, photosynthetic, unicellular microorganisms with high adaptability to environmental variations. Over the past decades, Chlorella has been used for the large-scale production of biomass. In addition, Chlorella has been actively used in various food industries for improving human health because of its antioxidant, antidiabetic, and immunomodulatory functions. However, the major restrictions in microalgal biofuel technology are the cost-consuming cultivation, processing, and lipid extraction processes. Therefore, various trials have been performed to enhance the biomass productivity and the lipid contents of Chlorella cells. This study provides a comprehensive review of lipid enhancement strategies mainly published in the last five years and aimed at regulating carbon sources, nutrients, stresses, and expression of exogenous genes to improve biomass production and lipid synthesis.

• ALGAE
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• v.37 no.4
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• pp.265-279
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• 2022

The primary production (PP) by phytoplankton in marine ecosystems is essential for carbon cycling and fueling food webs. Hence, estimating the PP in the territorial sea of each country is a necessary step to achieving carbon neutrality. To estimate the PP in the territorial sea of the Republic of Korea from 2005 to 2021, we analyzed various physiochemical parameters, such as sea surface temperature (SST), Secchi depth, and concentrations of chlorophyll-a and nutrients in the seas of five regions, including the East Sea, West Sea, western South Sea, eastern South Sea, and the waters off Jeju Island. During the 17-year study period, the SST tended to increase, while the nutrient concentrations declined, except in the Jeju area. Overall, the PP did not show a specific temporal trend, but daily PP in the western South Sea was the highest among the five regions. Moreover, the maximum PP in the Korean territorial waters (76,450 km²) was estimated at 11,227 Gg C y^-1, which accounts for 0.03% of the global PP. The results may give insights into a better understanding of the PP, further resource utilization, and environmental sustainability in the studied region.

• Horticultural Science & Technology
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• v.32 no.3
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• pp.346-352
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• 2014

This research was carried out to investigate the effect of supplemental lighting on stable productivity of paprika (Capsicum annuum L.) during low radiation period of winter season. The supplemental lighting sources used in this research were high pressure sodium (HPS) and lighting emitting plasma (LEP). Photosynthetic photon flux density (PPFD) emitted from both lamps decreased as vertical distance from lamp increased. The PPFD of LEP lamps were twice more than that of the HPS lamp per unit distance, but the rate of decreased PPFD of t he LEP per unit distance was higher than that of HPS lamp. And different degrees of PPFD between HPS and LEP lamps by horizontal distance had a smaller degree of difference than by vertical distance at the 100 cm away point. As daily average PPFD measured at the top of the plant under the supplemental lighting during January, the supplemental lighting significantly increased radiation. Radiation of HPS and LEP lighting was 137% and 315% higher than control (without supplemental lighting = sunlight). Air temperature in the top of the plant was not significant different among treatments. HPS and LEP lighting had no effect on increase of flower settings. Leaf length and width with LEP lighting was the longest, photosynthetic was higher than those of other treatments. Supplemental lighting treatments significant increased fruit length and diameter. Especially LEP lighting treatment had a greater effect on fruit length and diameter. In conclusion, LEP lighting treatment during low radiation period greatly affected growth and production of paprika. Further research will be required for the suitable application of LEP lighting in paprika production.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.30 no.3
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• pp.259-270
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• 1985

Meteorological year variations for rice crop from 1973 to 1984 were compared by using air temperature and sunshine hour for nursery period, cooling index for reproductive stage and meteorological yield productivity index for ripening period. The most optimum transplanting date and heading date for crop yield based on real transplanting date-grain yield relationship or heading date-grain yield relationship, meteorological yield productivity index and actual results showed good agreement each other. Around May 26 for transplanting and August 10 for heading were the most optimum date in Indica/Japonica hybrid cultivars while these were about June 8 and August 23 for Japonica cultivars, respectively. On the other hand, theoretical late limiting heading date for safe ripening were August 20 for Indica/Japonica hybrid cultivars and August 30 for Japonica cultivars, respectively, for both methods, cumulative temperature method during ripening with 80% believable frequency and meteorological yield productive index method having 1000(kg/10a) yielding potential. Based on the yield forecast trial, the highest values of photosynthetic efficiency, 2.5%, and crop growth rate, 23g/㎡/day, were recorded during 30 days before rice heading. Considering the photosynthetic efficiency and solar radiation, the potential crop growth rate was more or less 30g/㎡/day and the biological grain yielding potential in a existing cultural practices was approximately 900-1000(kg/10a) in Milyang weather condition. To increase further yielding potential, either photosynthetic efficiency or harvest index or both should be improved by manipulating appropriate canopy architecture, plant spacing, fertilizer, chemical, etc.

• Journal of Bio-Environment Control
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• v.19 no.1
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• pp.1-5
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• 2010

This research was conducted to investigate difference of internal temperature, humidity, and plant growth according to covering materials in sweet pepper's greenhouse. For growing period, daily mean internal temperature was not different between glass (GH) and plastic film house (PH), but the changed volume was more PH than GH. Internal humidity deficit was more PH than GH as that was 4.3 $g{\cdot}m^{-2}$ and 5.6 $g{\cdot}m^{-2}$, respectively. In change of internal temperature effected by different intensity of external light, that of PH was fasted twice that of GH, and that's tendency was effected by difference of internal temperature for several hours after sunrise. Leaf growth and photosynthetic product were more GH than PH, productivity of GH was better 80 percents than PH. As results, To improve productivity in PH compared with productivity in GH need to be the detailed managements of internal environmental factors in early period after sunrise.

• Journal of Korea Water Resources Association
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• v.45 no.12
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• pp.1293-1307
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• 2012

This study is to evaluate the RHESSys (Regional Hydro-Ecological Simulation System) simulated streamflow (Q), evapotranspiration (ET), soil moisture (SM), gross primary productivity (GPP) and photosynthetic productivity (PSNnet) with the measured data. The RHESSys is a hydro-ecological model designed to simulate integrated water, carbon, and nutrient cycling and transport over spatially variable terrain. A 8.5 $km^2$ Seolma-cheon catchment located in the northwest of South Korea was adopted. The catchment covers 90.0% forest and the dominant soil is sandy loam. The model was calibrated with 2 years (2007-2008) daily Q at the watershed outlet and MODIS (Moderate Resolution Imaging Spectroradiometer) GPP, PSNnet and 3 year (2007～2009) daily ET data measured at flux tower using the eddy-covariance technique. The coefficient of determination ($R^2$) and the Nash-Sutcliffe model efficiency (ME) for Q were 0.74 and 0.63, and the average $R^2$ for ET and GPP were 0.54 and 0.93 respectively. The model was validated with 1 year (2009) Q and GPP. The $R^2$ and the ME for Q were 0.92 and 0.84, the $R^2$ for GPP were 0.93.

• Journal of Bio-Environment Control
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• v.19 no.2
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• pp.97-108
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• 2010

The present study was conducted to investigate photosynthetic responses (Pn), chlorophyll fluorescence (Pe), chlorophyll contents of Allium victorialis var. platyphyllum, Ligularia fischeri, and Ligularia stenocephala growing at four different fertilizing schemes (non-fertilizing and 2.5 $g{\cdot}l^{-1}$, 5 $g{\cdot}l^{-1}$, 10 $g{\cdot}l^{-1}$ fertilizing). Three wild vegetables showed outstanding Pn and Pe at 5 $g{\cdot}l^{-1}$ fertilizing treatment. 10 $g{\cdot}l^{-1}$ of fertilizer, however, proved to be too much eventually leading to declined growth. A. victorialis var. platyphyllum showed good Pn and Pe under shade treatment whereas Pn and Pe of L. fischeri, and L. stenocephala showed the opposite tendency. The chlorophyll contents of the three wild vegetables showed the highest measurement ranging between 11.70~24.36 $mg{\cdot}g^{-1}$ when treated with 5 $g{\cdot}l^{-1}$ of fertilizer. Also it was showed that there were more chlorophyll contents under shade treatment as opposed to full sun. These results showed that 5 $g{\cdot}l^{-1}$ fertilizing treatment is optimal fertilizing of three wild vegetables and fertilizing and light intensity controlling is very important for productivity of vegetables.

• Applied Biological Chemistry
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• v.36 no.6
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• pp.488-494
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• 1993

A photosynthetic bacterium strain P17 having high growth rate and assimilating ability of organic acids was isolated from several soil samples, which was identified as Rhodospirillum rubrum. Cultural conditions of the strain P17 were examined for the production of starter culture used in the treatment of organic waste water. The addition of organic acids mixture as carbon source containing 0.2% Na-acetate, 0.1% Na-propionate and 0.2% Na-lactate and 0.1% of yeast extract as growth factor stimulated the cell growth. The maximal cell production was obtained at $30^{\circ}C$, pH 7.0, 2,500 lux of illumination and $50{\sim}100\;rpm$ of agitation. Under the optimal conditions of batch and fed-batch culture systems in a Jar fermentor, 5.17 g/l and 7.93 g/l of cells were obtained after S days of cultivation, respectively. In continuous culture system, the cell productivity was 0.206 g/l/h at a dilution rate of 0.21 $h^{-1}$. When R. rubrum P17 was cultivated in a soybean curd waste water, initial COD level(3,240 mg/l) of the waste water was reduced to 250 mg/l after 4 days of cultivation.