• Korean Journal of Soil Science and Fertilizer
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• v.45 no.5
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• pp.853-860
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• 2012

To estimate potential use of fly ash in reducing $CH_4$ and $CO_2$ emission from soil, $CH_4$ and $CO_2$ fluxes from a paddy soil mixed with fly ash at different rate (w/w; 0, 5, and 10%) in the presence and absence of fertilizer N ($(NH_4)_2SO_4$) addition were investigated in a laboratory incubation for 60 days under changing water regime from wetting to drying via transition. The mean $CH_4$ flux during the entire incubation period ranged from 0.59 to $1.68mg\;CH_4\;m^{-2}day^{-1}$ with a lower rate in the soil treated with N fertilizer due to suppression of $CH_4$ production by $SO_4^{2-}$ that acts as an electron acceptor, leading to decreases in electron availability for methanogen. Fly ash application reduced $CH_4$ flux by 37.5 and 33.0% in soils without and with N addition, respectively, probably due to retardation of $CH_4$ diffusion through soil pores by addition of fine-textured fly ash. In addition, as fly ash has a potential for $CO_2$ removal via carbonation (formation of carbonate precipitates) that decreases $CO_2$ availability that is a substrate for $CO_2$ reduction reaction (one of $CH_4$ generation pathways) is likely to be another mechanisms of $CH_4$ flux reduction by fly ash. Meanwhile, the mean $CO_2$ flux during the entire incubation period was between 0.64 and $0.90g\;CO_2\;m^{-2}day^{-1}$, and that of N treated soil was lower than that without N addition. Because N addition is likely to increase soil respiration, it is not straightforward to explain the results. However, it may be possible that our experiment did not account for the substantial amount of $CO_2$ produced by heterotrophs that were activated by N addition in earlier period than the measurement was initiated. Fly ash application also lowered $CO_2$ flux by up to 20% in the soil mixed with fly ash at 10% through $CO_2$ removal by the carbonation. At the whole picture, fly ash application at 10% decreased global warming potential of emitted $CH_4$ and $CO_2$ by about 20%. Therefore, our results suggest that fly ash application can be a soil management practice to reduce green house gas emission from paddy soils. Further studies under field conditions with rice cultivation are necessary to verify our findings.

• Korean Journal of Environmental Agriculture
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• v.26 no.3
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• pp.228-232
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• 2007

Slow-release fertilizers (SRF) have been used to reduce nutrient loss through increasing fertilizer efficiency and to save labor. Several SRFs were developed for rice plant in Korea, but there is few for horticultural crop plants. Two slow-release complex fertilizers, 100T and 150T, which made for controlling nitrogen release time up to 100 and 150 days, respectively, were selected for the incubation test cto evaluate nitrogen (N) release rate in soil. The N of urea selected as the control was completely released within a week after application. Sixty three and 53% of total N were released from 110T and 150T of slow release fertilizers within 8th weeks after application, respectively. For pepper cultivation CF110 and CF150, new slow-release complex fertilizer, were made of mixing 40% of conventional fertilizer and 60% of 110T and 150T, respectively, based on the amount of recommended fertilizer for pepper cultivation $(N-P_2O_5-K_2O=190-112-149\;kg\;ha^{-1})$, and were totally applied before pepper transplanting in the field as the basal fertilizer. Inorganic N $(NH_4^+-N+NO_3^--N)$ concentration in soil was higher in the CF110 treatment than in the control (NPK) at all period of pepper cultivation. In the CF150 treatment concentration of inorganic N in soil was low compared to control up to 8th weeks after transplanting. However, there was no difference in plant height and nutrient content of pepper leave between CF110 treatment and the control. In comparison, plant height was significantly lower in CF150 than the control and CF110 treatments. Around 4% of fresh pepper yield was increased in CF110 compared to the control, but it was decreased to about 2% by CF150 treatment. Conclusively, CF110 form could be recommended as a slow release fertilizer for pepper cultivation.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.53 no.3
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• pp.273-278
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• 2008

This study set out to investigate the changes to the growth, yield, and flavonoid contents of mungbean according to different seeding times from mid May to mid July in the southern region of Korea. Days to first flowering, days to first maturing, and cultivation period were shorter at later seeding time than earlier seeding time. But later the seeding time was, days from first maturing to first harvesting, days required between harvesting increased. Number of pods at first harvesting and yield of mungbean were highest when seeded at late June, showing increase in yield 14% more than at early June as standard seeding time. However number of seeds per pod and 1,000-seed weight at first harvesting were highest when seeded at mid July. The number of harvesting was smallest at two times when seeded at June or mid July. The contents of average vitexin and isovitexin in mungbean were highest in the order of mid July, late June, and mid May. In particular, their contents reached its highest point in the seeds of the second harvest. Considering the results of the cultivation period, yield, harvesting times, vitexin and isovitexin contents, the proper seeding time of mungbeans in the southern region of Korea will be from late June to mid July.

• The Korean Journal of Food And Nutrition
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• v.27 no.5
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• pp.897-905
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• 2014

The foliage of sweet potato [Impomoea batatas (L.) Lam] is an excellent source of food material due to the functional components of polyphenol and carotenoid. In this study, the lightness (L-value), polyphenol contents, and DPPH radical scavenging activity of the foliage of Shinwhangmi, Hayanmi and Suioh cultivars harvested after different cultivation periods (60, 90 and 120 days after planting) and according to tip locations (1st~5th, 6th~10th, 11th~15th tips) were investigated. As a result, Shinwhangmi showed a lower lightness value (60 days after planting and 1st~5th tips). The longer the cultivation periods and the closer the tips, the higher the contents of polyphenol and DPPH radical scavenging activity were in lyophilized foliage of Shinwhangmi, Hayanmi and Suioh. In the 1st~10th tip of Shinwhangmi, Hayanmi and Suioh cultivated for 90 days and dried by 2 step hot-air (1st: $70^{\circ}C$ for 8 hr, 2nd: $80^{\circ}C$ for 4 hr), the polyphenol and ${\beta}$-carotenoid contents were 5.0, 3.9 and 4.0 mg/g and 75.6, 71.6 and 63.1 mg/g, respectively. The DPPH radical scavenging activities and ABTS radical scavenging activities ($EC_{50}$) were 0.29, 0.36 and 0.33 mg and 0.12, 0.15 and 0.11 mg, respectively. These antioxidative activities were over two times stronger than spinach.

• Journal of Bio-Environment Control
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• v.29 no.4
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• pp.456-463
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• 2020

This research was conducted to examine the changes in yield and difference in growth, using rootstocks in tomatoes as the growth indicators. Seedlings of tomato 'Gama', were used as scion and non-grafted control, while 4 different grafted tomatoes 'Powerguard', 'T1', 'L1', and 'B.blocking' were used as rootstocks. The non-grafted and grafted plants were grown in hydroponics for long-duration cultivation under plastic greenhouse conditions. The total yield of grafted tomato 'Powerguard' and non-grafted tomato 'Gama' were 8,428 g and 7,645 g, respectively. The flowering position of grafted plants 'B.blocking' and non-grafted plants at the latter period were 17.58 cm and 14.92 cm, respectively. The results showed that the yield and the balance of the plant were improved until the end of the harvest by grafting. The difference in yield between non-grafted and grafted tomatoes was evident in the 19th cluster, 236 days after planting. Therefore using rootstocks could be advantageous for long-duration cultivation in tomatoes.

• Journal of Environmental Science International
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• v.28 no.9
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• pp.729-735
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• 2019

The aim of this study was to determine the effects of different compositions of environmental substrates on hydroponic tomato cultivation. Three different substrates were used in coir chip:dust (v/v=50:50; CP1), coir chip:dust (v/v=80:20; CP2), and rock wool cube with CP2 (CPR). The amount of irrigation during the cultivation period was 190 mL/(plant time) in all substrates. The pH and EC were 5.8-6.2 and 2.6-2.9 dS/m, respectively. The drainage rate in CP1 was 31%, in CP2 was 36%, and in CPR was 29%. The growth of tomato plants in terms of height was higher in CP1 and CPR. The leaf area was greater in CP2. The fresh and dry weights were greater in CP2 and CPR treatments. The net photosynthesis in CP2 ($19.31{\mu}mol\;CO_2/m^2s$) and root activity in CP2 were higher among all three treatments. The soluble solid content of fruit was not significantly different among treatments. The yield per plant in CP2 and CPR treatments was 17% greater than the yield per plant in CP1. Therefore, the most suitable substrate for hydroponic tomato cultivation is the substrate mixed with coir chip:dust (v:v=80:20; CP2), i.e., CPR.

• Journal of Bio-Environment Control
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• v.23 no.4
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• pp.371-375
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• 2014

This study was carried out to get the basic data to practically design an artificial light-used plant factory system for common ice plant (Mesembryanthemum crystallinum L.) cultivation. The adequate range of light intensity was $120-200{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ and the carbon fixed rates was $0.84nmolCO_2{\cdot}cm^{-2}{\cdot}s^{-1}$. When the planting density, light intensity, and yield were $0.0225m^2$ ($15{\times}15cm$), $200{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$, and 1,000 plants per day, the total number of the plants, cultivated area, and total light intensities were estimated as 25,000 plants, $563m^2$, and $140,625{\mu}mol{\cdot}s^{-1}$, respectively. About 153.2kW with 2,785 fluorescent lights (FL) needed for the electric power and the electricity charges was 2.46 million won for one month. At a harvest rate of 1,000 plants per day in closed-type plant factory, the light installation cost, total installation cost, and total production cost were 27.85, 83.56, and 100.27 million won, respectively. The production cost per plant including labor cost was calculated as 370 won, providing that the cultivation period was 25 days and marketable ratio was 80%. Considering the annual total expenses, incomes, and depreciation cost, the sales cost per plant could be estimated around 970 won or higher.

• Journal of The Korean Society of Grassland and Forage Science
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• v.27 no.2
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• pp.79-84
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• 2007

This study was carried out to investigate the effects of growing period and cultivars on physiological characteristics and photosynthetic rates of kenaf in Cheorwon, Korea, The possibility of their utilization as forage plant was also discussed. A split plot design composing 3 growing periods (53, 84 and 115 days after sowing) and 3 cultivars (Dowling, Everglade-41 and Tainung-2) was applied for this experiment. Leaf photosynthetic rate was highest 28.6 $CO_2{\mu}mol\;m^{-2}s^{-1}$ in Everglade-41 at the beginning of August when solar irradiation was most intense. In the final biomass of kenaf, Dowing wa the highest among cultivars, with 534.6g/F.W./plant and 109.6g/D.W./plant, respectively. In addition, Dowling was the best in stem thickness among cultivars evaluated. Our results exhibited that all cultivars planted in Cheorwon exhibited decreased yield production compared to a previous report experimented in Jaeju. It may result that cultivation in Jaeju utilized wider planting space and longer cultivating time. In the basis of our data, it is suggest that extending cultivation time and using wider planting space should increase yield in Cheorwon with potential utilization of kanef as a forage crop.

• Korean Journal of Plant Resources
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• v.29 no.4
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• pp.393-399
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• 2016

This study was conducted to elucidate the photosynthetic response to the environment and establish optimum cultivation conditions for the Korean endemic plant, Aster koraiensis. Photosynthetic characteristics according to growth stage, light, CO₂, and soil water potential were investigated. During the first year of transplanting, photosynthetic rates were drastically increased until June, after which they slowly declined, During the second year, photosynthetic rates declined throughout the entire growth period. The highest level of light compensation point was shown the early growth stage. Photosynthetic rates affected by intercellular CO₂ concentration were maintained or decreased over the CO₂ saturation point. The lowest CO₂ compensation point was 16.1 μmol·mol⁻¹ during March. The morphological changes of leaves were observed due to shading with chlorophyll contents increasing. Photosynthetic rates were higher at 0% and 50% shading treatments than at 75%. There were rarely any morphological changes of leaves due to soil moisture, however, changes to leaf compactness were observed. Photosynthetic rate, apparent quantum yield, and respiration rate increased, whereas water use efficiency decreased over −25 kPa of soil moisture.

• Microbiology and Biotechnology Letters
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• v.47 no.4
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• pp.603-613
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• 2019

This study was carried out to examine the antagonistic effect against phytopathogenic fungi of isolated strains from soil samples collected from Busan, Changwon, and Jeju Island: Botrytis cinerea, Colletotrichum acutatum, Corynespora cassiicola, Fusarium sp., Rhizoctonia solani, Phytophthora capsici, and Sclerotinia sclerotiorum. According to results of our studies, isolated strains showed an antagonistic effect against phytopathogenic fungi. Such an antagonistic effect against phytopathogenic fungi is seen due to the production of siderophores, antibiotic substances, and extracellular amylase, cellulase, protease, and xylanase enzyme activities. Extracellular enzymes produced by isolated strains were significant, given that they inhibited the growth of phytopathogenic fungi by causing bacteriolysis of the cell wall of plant pathogenic fungi. This is essential to break down the cell wall of plant pathogenic fungi and thus help plant growth by converting macromolecules, which cannot be used by the plant for growth, into small molecules. In addition, they are putative candidates as biological agents to promote plant growth and inhibit growth of phytopathogenic fungi through nitrogen fixation, indole-3-acetic acid production, siderophore production, and extracellular enzyme activity. Therefore, this study suggests the possibility of using Bacillus subtilis ANGa5, Bacillus aerius ANGa25, and Bacillus methylotrophicus ANGa27 as new biological agents, and it is considered that further studies are necessary to prove their effect as novel biological agents by standardization of formulation and optimization of selected effective microorganisms, determination of their preservation period, and crop cultivation tests.