• Korean Journal of Ecology and Environment
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• v.52 no.3
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• pp.192-201
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• 2019

While a fairly large amount of organic matter is produced daily via phytoplankton photosynthesis in Lake Paldang, South Korea, knowledge of the role of algal-derived organic matter (OM) as a refractory OM source is not adequate. To understand the contribution of algal-derived OM to the refractory pool, biodegradation experiment and $KMnO_4$ oxidation experiment were conducted for 60 days using $^{13}C$ and $^{15}N$ labeled natural phytoplankton assemblage. The assemblage was collected from Lake Paldang on May 20, 2010. The photosynthetically produced total organic carbon ($TO^{13}C$), particulate organic carbon ($PO^{13}C$), and particulate nitrogen ($P^{15}N$) remained at 26%, 20%, and 17% of the initial concentrations, respectively, in the form of non-biodegradable organic matter. In addition, 12% and 38% of $PO^{13}C$ remained after $KMnO_4$ treatment on Day 0 and 60, respectively. These results indicate that photosynthetic products could be an important source of refractory organic matter after microbial degradation. Moreover, the microbially transformed algal-derived OM could contribute to the oxidation rate of the chemical oxygen demand.

• ALGAE
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• v.34 no.1
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• pp.7-21
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• 2019

The genus Heterocapsa is one of the major dinoflagellate groups, with some of its species having worldwide distributions. However, prior to the present study, the phototrophic species Heterocapsa minima has been reported only from the northeast Atlantic Ocean. Recently, H. minima was found in the Korean waters, and a clonal culture was established. This culture was used to examine the morphology of the Korean strain H. minima HMMJ1604 through light and scanning electron microscopy, as well as for its genetic characterization. Furthermore, to determine the nationwide distribution of H. minima in Korea, its abundance was quantified in the waters of 28 stations in all four seasons in 2016-2018 using the quantitative real-time polymerase chain reaction method. The overall morphology of H. minima HMMJ1604 was very similar to that of the Irish strain H. minima JK2. However, the Korean strain had five pores around the pore plate, whereas the Irish strain had six pores. When properly aligned, the sequences of the large subunit and internal transcribed spacer regions of the ribosomal DNA of the Korean strain were identical to those of the Irish strain. This species was detected in the waters of 26 out of 28 stations, but its abundance was greater than $1.0cells\;mL^{-1}$ at 8 stations. The highest abundance of H. minima was $44.4cells\;mL^{-1}$. Although this species was found in all seasons, its abundance was greater than $1.0cells\;mL^{-1}$ when the water temperature and salinity were $10.9-25.0^{\circ}C$ and 17.5-34.1, respectively. To the best knowledge, the present study reported for the first time that H. minima lives in the Pacific Ocean and is widely distributed in the Korean waters.

• Journal of Bio-Environment Control
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• v.28 no.2
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• pp.104-109
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• 2019

The crops recommended for the plant factory system are diverse. The importance of planting density in the plant factory is being recognized. The objective of this study was to determine the optimal planting density for growth and quality of kohlrabi in a closed-type plant factory system. The kohlrabi was grown under fluorescent lamps and nutrient film technique system. The growth and quality of kohlrabi were investigated under four different planting densities ($22plants/m^2(15{\times}30cm)$, $27plants/m^2(15{\times}25cm)$, and $33plants/m^2(15{\times}20cm)$). There were no significant interactions between Shoot fresh and dry weights per plant or bulb stem fresh and dry weights per plant and planting density. Shoot fresh and dry weight per area or bulb stem fresh and dry weight per area were the highest at $33plants/m^2$. There were no significant interactions between plant height, leaf area, photosynthetic rate, hardness, and chlorophyll content and planting density. Significant differences in Bulb stem height and diameter, and brix were observed. Bulb stem height and diameter and brix of kohlrabi were the highest at $22plants/m^2$. Based on our results, we conclude that the optimal planting density is $33plants/m^2$ for growth of kohlrabi, however, the optimal planting density is $22plants/m^2$ for quality of kohlrabi in a closed-type plant factory system.

• Journal of Korean Society of Forest Science
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• v.100 no.2
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• pp.305-313
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• 2011

Fertilization is essential to seedling production in nursery culture, but excessive fertilization can contaminate surface and ground water around the nursery. The objective of this study was to find optimal fertilization practice of container seedling production for reducing soil and water contamination around the nursery without compromising seedling quality. This study was conducted to investigate growth performance, photosynthesis, chlorophyll fluorescence, and chlorophyll contents of Liriodendron tulipifera growing under three different fertilization treatments (Constant rate, Three-stage rate, and Exponential rate fertilization). Root collar diameter, height, and biomass of L. tulipifera were the highest at Constant treatment. Like growth performance, seedling quality index (SQI) were higher at Constant than at other treatments, but not significantly different among treatments. L. tulipifera showed good photosynthetic capacity at all treatments. Photochemical efficiency and chlorophyll contents were significantly lower at Exponential than at other treatments. Therefore, Exponential fertilization which is 50% fertilizer of other treatments would maximize seedling growth and minimize nutrient loss.

• Journal of Korean Society of Forest Science
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• v.100 no.2
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• pp.212-217
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• 2011

A photoautotrophic micropropagation methodology in liquid culture medium has a number of advantages for large-scale propagation of plants. This paper describes an improved system for the mass propagation via somatic embryogenesis of the medicinal plant Kalopanax septemlobus Nakai. Somatic embryo-derived young plantlets of K. septemlobus were cultured either under heterotrophic conditions with sucrose on half-strength MS medium with $30gL^{-1}$ sucrose, under heterotrophic conditions without sucrose, or under photoautotrophic conditions (MS liquid medium without sucrose under forced aeration) for four weeks before transferring the plantlets for acclimatization. Plantlets grown under photoautotrophic conditions had more leaves, higher chlorophyll content, a higher net photosynthetic rate (NPR), and a higher survival rate. The results indicate that the photoautotrophic conditions with a forced ventilation system are effective in enhancing the growth of plantlets and the rate of net photosynthesis. The plantlets grown under photoautotrophic conditions had a high survival rate (92%) upon ex vitro transplantation. Our study shows that autotrophically produced plantlets acclimatize better and sooner upon ex vitro transplantation than conventionally cultured plants.

• Korean Journal of Agricultural and Forest Meteorology
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• v.23 no.2
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• pp.100-107
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• 2021

An agrivoltaic system (AVS) is a system of innovation that comprises productions of photovoltaic power and agricultural crops on the same area. However, the decline in crop yield will be fatally occurred because the pigments of crop absorbs less light energy under AVS. In addtion, the photosynthetic capacity of crop grown under the partial shading of AVS is not well reported. In this study, the electron transport rate (ETR) and non-photochemical fluorescence quenching (NPQ) of soybean and rice under the AVS in Boseong and Naju was investigated using chlorophyll fluorescence measurement. The ETR value of soybean and rice under AVS were not significantly differed by location. It represents that the photophosphorylation rate of the crops is not critically different. It means that the decreases in total photosynthesis under AVS were mostly affected by the amount of light absorbed by leaves. Under AVS the photosynthesis of crops will be lower than field crops grown in open fields. This is because the crops under AVS observed higher NPQ, which means that the available energy cannot distribute to photophosphorylation reaction.

• Microbiology and Biotechnology Letters
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• v.49 no.1
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• pp.101-110
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• 2021

Interactions between microalgae and heterotrophic bacteria are common in natural environments. This study investigated the effect of heterotrophic bacteria on the activity of the photosynthetic eukaryotic alga Chlorella sp. MF1907 when cocultured. A total of 31 heterotrophic bacterial isolates belonging to different genera were cocultured with MF1907. Interactions of the alga with Agromyces, Rhodococcus, Sphingomonas, Hyphomicrobium, Rhizobium, and Pseudomonas were positive, while those with Burkholderia, Paraburkholderia, Micrococcus, Arthrobacter, Mycobacterium, Streptomyces, Pedobacter, Mucilaginibacter, Fictibacillus, Tumebacillus, Sphingopyxis, and Erythrobacter were negative (p < 0.05). A turnover experiment demonstrating a switch from heterotrophic to autotrophic activity of MF1907 was performed using 16 isolates exhibiting apparent effects (positive, negative, or neutral). Compared with the results of the coculture experiment, eight isolates exhibited the same outcomes, while the others did not. Consistently, Pseudomonas and Agromyces showed a remarkable positive effect on MF1907 activity, and Burkholderia, Streptomyces, and Erythrobacter had a marked negative effect. Our results suggest that it may be possible to use the isolates for controlling populations of microalgae in natural and engineered environments.

• Journal of agriculture & life science
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• v.53 no.6
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• pp.13-21
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• 2019

The influences of light generated by LEDs on shoot growth and photosynthesis of Tea plant(Camellia sinensis L.) were evaluated. The growth characteristics were investigated after 45 days of culture under four different light qualities: fluorescent lamp, red LED, blue LED, red+blue+white LED. Shoot growth was promoted by red light, especially root length and area were further promoted under the red+blue+white LED. Also, T/R ratio and Chlorophyll content were highest in red+blue+white. Fluor Cam was used to measure the fluorescence images of the plants, inhibition of photochemical efficiency(Fv/Fm) were not changed in all treatment. However, non-photochemical quenching(NPQ) were found rapidly increasing in blue LED, these results were that blue LED were inhibit photosynthetic efficiency and must be considered for efficiently in vitro cultivation of the tea plant. The above results suggest that light qualities could be an important factor to foster in vitro growth of the species. Also, In order to produce healthy plants, it is effective to using light qualities of red+blue+white LED on in vitro culture of the tea plant. These results could be used to mass propagating shoot and produce of healthy seedling.

• Korean Journal of Agricultural and Forest Meteorology
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• v.23 no.1
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• pp.82-88
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• 2021

Sun-induced fluorescence (SIF) retrieval using remote sensing technique has been used in an effort to understand the photosynthetic efficiency and stress condition of vegetation. Although optical devices and SIF retrieval methodologies were established in order to retrieve SIF, the SIF measurements are domestically sparse. SIF data of paddy rice w as measured in Naju, South Korea from June 10, 2020 to October 5, 2020. The SIFs based red (O2A) and far-red (O2B) w ere retrieved using a spectral fitting method and an improved Fraunhofer line depth, and photosynthetically active radiation was also produced. In addition, the SIF data was filtered considering solar zenith angle, saturation conditions, the rapid and sudden change of solar irradiance, and sun glint. The provided SIF data can help to understand a SIF product and the filtering method of SIF data can contribute to producing high-quality SIF data.

• Korean Journal of Remote Sensing
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• v.36 no.6_1
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• pp.1339-1348
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• 2020

Phytoplankton controls marine ecosystems in terms of nutrients, photosynthetic rate, carbon cycle, etc. and the degree of its influence on the marine environment depends on their physical size. Many studies have been attempted to identify marine phytoplankton size classes using the remote sensing techniques. One of successful approach was the three-component model which estimates the chlorophyll concentrations of three phytoplankton size classes (micro-phytoplankton; >20 ㎛, nano-; 2-20 ㎛ and pico-; <2 ㎛) as a function of total chlorophyll. Here, we examined the applicability of Geostationary Ocean Colour Imager (GOCI) to the mapping of the phytoplankton size class distribution in the East Sea. A fit of the three-component model to a biomarker pigment dataset collected in the study area for some years including a large harmful algal bloom period has been carried out to derive size-fractioned chlorophyll concentration (CHL). The tuned three-component model was applied to the hourly GOCI images to identify the fractions of each phytoplankton size class for the entire CHL. Then, we investigated the distribution of phytoplankton community in terms of the size structure in the East Sea during the harmful Cochlodinium polykrikoides blooms in the summer of 2013.