• Korean Journal of Microbiology
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• v.38 no.1
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• pp.31-37
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• 2002

For elucidating the correlation between the eubacterial community structure and environmental parameters in Nammae Reservoir located in Kyungsan, Kyungbuk, the bacterial community structure and their structure affecting environmental parameters were analyzed using Fluorescent In Situ Hybridization (FISH) monthly over year. $\alpha$ . $\beta$ . $\gamma$-subclasses of Proteobacteria and Cytophaga-Flavobacterium (CF) group known as dominant bacterial group in freshwater were detected in 3 stations over year. The ratio of each subclass to total bacteria was determined; $\alpha$.$\beta$ . $\gamma$-subclasses and CF group varied in the range of 4.0~29.2%, 1.7~25.8%, 1.8~12.8%, 4.9~36.3%, respectively and there was no substantial differences between stations. In terms of the correlation between each group specific bacteria and environmental parameters such as temperature, SS, pH, DOC, NH$_4$-N, NO$_3$-N, PO$_4$-P, standing crops of algae, the results were as follows: 1) total bacterial numbers correlated positively with temperature, SS and DOC, 2) Eubacteria positively with DOC and Chl-$\alpha$, 3)${\gamma}$-subclass positively with DOC, and 4) CF group positively with standing crops of chlorophyceae, 5) whereas $\beta$-subclass bacteria correlated negatively with standing crop of cyanobacteria and that of total algae.

• Korean Journal of Ecology and Environment
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• v.49 no.4
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• pp.375-384
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• 2016

Phytoplankton community is one of the important factors for the management of aquatic environment due to generation of varying toxins by harmful algal species. This study was performed to examine the phytoplankton community structure (PCS) in the midstream of Geum River (GR) from January 2014 to December 2015. The water sampling was performed in five stations on 2014, and three stations on 2015. Subsequently, the morphological identification was performed by microscopic observation in laboratory condition. As results, total 265 species were identified and it was comprised of 40.8% of Bacillariophyceae, 9.1% of Cyanophyceae, 44.5% of Chlorophyceae, and the others (4.9%). During the investigation period, total average standing crop of phytoplankton was $12,948cells\;mL^{-1}$, and it was comprised of $7,702cells\;mL^{-1}$ of Bacillariophyceae, $2,821cells\;mL^{-1}$ of Cyanophyceae, $2,121cells\;mL^{-1}$ of Chlorophyceae, and $305cells\;mL^{-1}$ of others. To verify which tributaries of upstream area influence on PCS of midstream of GR, the phytoplankton standing crops of two stations including Mihocheon (MH) and Gapcheon (GC) were examined on 2014, and compared to result of on 2015. The results were shown that the MH station had more similar phytoplankton standing crops with midstream of GR than GC station. The relationship between environmental parameters and phytoplankton dynamics was studied at the investigated station. As results, whereas water temperature and total phosphorus were represented the positive correlation, N/P ratio was remarkably exhibited negative correlation. From the results, it is suggested that the PCS of midstream of GR was more affected by MH station than GC station, and the changes of temperature, phosphorus concentration, and N/P ratio may be important factors on the PCS formation of midstream of GR.

• Journal of The Korean Society of Grassland and Forage Science
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• v.38 no.2
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• pp.84-90
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• 2018

Cultivation of high-quality forage crop by using fallow field during winter is required for national high feed self-sufficiency and establishment of self-supply system of high-quality forage crop. Field experiments for cultivation of high-quality winter forage crop were conducted at the paddy and upland fields in Cheonan and Anseong city with treatments of single Italian ryegrass(IRG) and IRG mixed with forage barley at the paddy field and of single forage barley and forage barley mixed with IRG at the upland field in the Mid-west plain. Several cultivation conditions such as broadcasting IRG seed under standing rice, sowing time, tillage method, drainage condition, mixed sowing with forage barley were compared to know the change of growth, yield and quality of winter forage crop. In particular, over-wintering rate and dry matter yield were decreased significantly in late-sown IRG and moisture-stressed forage barley. Yield and quality of forage crops were increased by sowing after tillage, mixed sowing of IRG with barley at the paddy field with good drainage. High yield as much as dry matter $10MT\;ha^{-1}$ with high feed value could be obtained by early sowing of feed barley mixed with IRG at the upland field. Cultivation conditions such as early sowing, sowing after tillage, drainage management are required for higher dry matter yield, quality and stable cultivation of winter forage crops in the mid-west plain of Korea.

• Korean Journal of Medicinal Crop Science
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• v.14 no.2
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• pp.96-100
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• 2006

Regions of allelic loss on chromosomes in many tumors of human and some experimental animals are generally considered to harbor tumor-suppressor genes involved in tumorigenesis. Allelotype analyses have greatly improved our under-standing of the molecular mechanism of radiation lymphomagenesis. Previously, we and others found frequent loss of heterozygosity (LOH) on chromosomes 4, 11, 12, 16 and 19 in radiation-induced lymphomas from several $F_1$, hybrid mice. To examine possible contributions of individual tumor-suppressor genes to tumorigenesis in p53 heterozygous deficiency, we investigated the genome-wide distribution and status of LOH in radiation-induced lymphomas from $F_1$ mice with different p53 status. In this study, we found frequent LOH (more than 20%) on chromosomes 4 and 12 and on chromosomes 11, 12, 16 and 19 in radiation-induced lymphomas from $(STS/A{\times}MSM/Ms)F_1$ mice and $(STS/A{\times}MSM/Ms)F_1-p53^{KO/+}$ mice, respectively. Low incidences of LOH (10-20%) were also observed on chromosomes 11 in mice with wild-type p53, and chromosomes 1, 2, 9, 17 and X in p53 heterozygous-deficient mice. The frequency of LOH on chromosomes 9 and 11 increased in the $(STS/A{\times}MSM/Ms)F_1-p53^{KO/+}$ mice. Preferential losses of the STS-derived allele on chromosome 9 and wild-type p53 allele on chromosome 11 were also found in the p53 heterozygous-deficient mice. Thus, the putative tumor-suppressor gene regions responsible for lymphomagenesis might considerably differ due to the p53 status.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.45 no.1
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• pp.20-25
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• 2000

Viviparous germination causes yield loss and quality deterioration of rice. This study was conducted to investigate varietal differences of the viviparous germination with different days after heading (DAH) and different temperatures. In the laboratory examination, the averaged germination rate of all varieties at 45DAH and at 25DAH was 79.9%, and 27.5% under the incubation at the temperature of 3$0^{\circ}C$/2$0^{\circ}C$ (day/night) for 12 days. Andabyeo, Da- sanbyeo, and Nonganbyeo showed the lowest viviparous germination rates among the tested varieties. The shoot length of the viviparous germination measured 12days after incubation at 30/2$0^{\circ}C$ ranged from 21 to 53mm, indicating significant deterioration of rice quality. In the field test, the averaged viviparous germination rates of rice varieties at 25, 35, 45DAH with the underwater conditions for 4 days were 2.2, 6.2 and 9.2%, respectively, while their rates at 12 day after underwater conditions increased to 17.6, 44.2 and 43.8%, respectively. A variety that showed the highest viviparous germination rate at 25 and 35 and 45DAH was Heukjinjubyeo. When standing rice panicles without lodging were examined after consecutive raining for 7 days Juanbyeo showed the highest viviparous germination (45.5%), followed by Odaebyeo (16.0%), Jinbubyeo (14.5 %), Bongkwangbyeo (14.2 %) and Obongbyeo (12.6%). The viviparous germination of rice was greatly affected by variety, days after heading and temperature settings. Bongkwangbyeo, Juanbyeo, Dongjinbyeo, Hwasunchalbyeo, Naepoongbyeo and Heukjinjubyeo were classified as the most susceptible varieties to the viviparous germination in the field conditions.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.509-509
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• 2022

Rice has always been the anchor of food security in the Philippines and the government is adamant about sustaining rice production by ensuring reliable irrigation water availability. Among the numerous irrigation schemes, the importance of the Pulangui River Irrigation System (PRIS) is undeniable, as it is the largest and primary irrigation source for rice production areas which are considered the food basket in Northern Mindanao. However, the ageing irrigation structures, unlined canals, long-standing water delivery systems, and climate change are compromising the performance of PRIS; and every year, during the dry and wet season, the maximum rice irrigable area is not achieved. From the field-scale water management perspective, untimely irrigation application, an unregulated roster of turn for irrigation among farmers, and the traditional practice of flooding the rice fields are the main causes of substantial water losses in conveyance, distribution, and farm application of irrigation water. Hence, proper irrigation scheduling is crucial to cultivate the maximum irrigable area by ensuring equity among the farmers and to increase the water use efficiency and yield. In this study, the FAO single crop coefficient approach was adopted to estimate rice water requirements, which were subsequently used to suggest appropriate irrigation schedules based on the recommended field-scale rice cultivation practices. The study results would improve the irrigation system management in the study area by facilitating in regulating the canal water flows and releases according to suggested irrigation schedules that could lead to increased benefited area, yield, and water efficiency without straining the available water resources.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.62 no.4
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• pp.361-366
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• 2017

This study was conducted to evaluate effects of seeding rate and depth during broadcast sowing on growth and yield of foxtail millet and proso millet over 2 years. The rate of sowing seeds was adjusted to 5, 7, 10 and 20 kg per ha on foxtail millet, and 5, 10, 15 and 30 kg per ha for proso millet. Sowing depth was 0.5, 1, 3, 5, 7, and 10 cm used tractor rotary attachment for shallow-tilling. The rate of seedlings standing when foxtail millet and proso millet were sowed to a depth of 0.5~5 cm was 72.0~78.0% and 73.0~80.5%, respectively. Plant height and weight at the three-leaf stage after emergence was highest for the treatment with 3 cm rotary depth. As the rate of broadcast seed sowing increased, plant length, diameter, seed length, and seeds on the panicle decreased. The grain yield of foxtail millet was highest with broadcast seed sowing of 10 kg per ha (3652, $3977kg\;ha^{-1}$) and proso millet was highest at broadcast seed sowing of 15 kg per ha (2226, $2052kg\;ha^{-1}$) in 2012 and 2013, respectively. Therefore, the optimum rate of sowed seeds under broadcast cultivation was $10kg\;ha^{-1}$ for foxtail millet and $15kg\;per\;ha^{-1}$ for proso millet. Optimum sowing depth for foxtail and proso millet under broadcast cultivation was 3 cm, using a rotary tractor attachment for shallow-tilling.

• Journal of Korean Society on Water Environment
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• v.29 no.3
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• pp.428-437
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• 2013

Physico-chemical water quality parameters and the phytoplankton communities from 12 sites in Oship-stream, Songchunstream, and Namdae-stream, located Gyeongsangbukdo Uljin-gun, Yeongdeok-gun, and Pyeonghae-eup respectively, were investigated from April 2009 to February 2010. Oship-stream, which is an open estuary, was easily affected by ocean current compared to that of Songchun-stream and Namdae-stream. OS3 and OS4 conductivity was higher with a season average of 3,397 ${\mu}s/cm$. The streams were mesotrophic to hypertrophic. Biological oxygen demand (BOD) was about 3mg/L, which was level 2 on the water quality ratings, but a concentration of 5mg/L in April 2009 indicated increased pollution due to drought. A total of 118, 117, and 124 phytoplankton taxa were found in Oship-stream, Songchun-stream, and Namdae-stream, respectively. The apparent dominant species in the polluted waters included Cryptomonas ovata, Fragilaria construens var. venter, Oscillatoria limnetica, O. limosa, and Phormidium tenue. All of Oship-stream, SC2 and SC4 of Songchun-stream, and ND3 of Namdae-stream were eutrophic as a result of standing crop analysis. BOD was highly correlated with chlorophyll-a content(r=0.52). Phosphorus concentration and proliferation of phytoplankton were thought to most affect BOD concentration in all three streams.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.37 no.2
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• pp.122-128
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• 2004

On the basis of monthly samples, we investigated the seasonal variation and feeding habits of amphipods inhabiting Zostera marina beds in Gwangyang Bay. Dominant species $(>1\%$ of the total number of amphipods) consist of 5 gammarids (Gammaropsis japonicus, Jassa slatteryi, Pontogenia rostrata, Atylus collingi and Ceinina japonica) and 1 caprellid (Caprella tsugarensis). Mean densities of amphipods varied from the highest of $63,148\;ind.\;m^{-2}$ in-May to the lowest of $1,247\;ind.\;m^{-2}$ in September. G. japonicus and J. slatteryi dominated in summer whereas C. japonica in autumn and winter. C. japonica was found to be a carnivorous feeder consuming mainly harpacticoid copepods and unidentified crustaceans, whereas G. japonicus, J. slatteryi, and C. tsugarensis consumed both phytoplankton and detritus. Seasonal densities of amphipods were significantly related with the shoot standing crop of the eelgrass and its epiphyte. Also densities of amphipods displayed significant difference in related with the shoot density of the eelgrass among sampling stations. These results suggest that the biological interactions between the eelgrass and amphipods as well as between the carnivorous and the herbivorous amphipods may be important in the seasonal variation of amphipods inhabiting Z. marine beds.

• The Korean Journal of Ecology
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• v.17 no.1
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• pp.59-67
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• 1994

Differences in physicochemical characteristics of sediment and changes in density, height and dry matter of shoots along different water depths were investigated in the stands of Zizania latifolza populations of the littoral zone of Lake Paltangho, Korea. Any significant differences in sediment chemistry were not found along water depth, although sand content decreased slightly with increasing depth. Shoot density of Zizania latqolia decreased with increasing water depth. In shallower water, many of the short shoots died in the early growth stages. The morphology of shoots was taller and heavier in deeper water. The distributions of shoot heights became negatively skewed and leptokurtic as plants grew, and these changes occurred in the earlier growth stages in deeper water. The standing crop of shoots increased with increasing water depth. These results suggest that Zizania lattfolia has a growth strategy for adjustment to deep water through decreasing shoot density and increasing height.