• Korean Journal of Soil Science and Fertilizer
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• v.50 no.5
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• pp.489-496
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• 2017

This study was conducted to test the applicability of hydroxy radical reactor system, which applied advanced oxidation processes, to sterilize pathogenic bacteria for nutrient solution recycling in closed hydroponics. Removal efficiency was tested on 25 L of nutrient solution maxed with 10 mL culture solution of bacteria, E. coli, and R. solanacearum in a pilot tank. The testing conditions included various levels of hydroxy radicals resulting from air flow rates of 40, 80, and $120L\;min^{-1}$, and 12 hours processing time. The removal of bacteria, E. coli, and R. solanacearum by hydroxy radical in nutrient solution was significantly increased with an increase in the flow rate of the air from $40L\;min^{-1}$ to $120L\;min^{-1}$. The optimum removal efficiency was achieved at an air flow rate of $120L\;min^{-1}$ for 2 hours treatment. There were no significant differences in removal efficiency among bacteria, E. coli, and R. solanacearum for tested level and time of hydroxy radical. These results verified the efficiency of hydroxy radical in removing the pathogenic bacteria and the applicability of hydroxy radical reactor system in the field.

• Journal of Bio-Environment Control
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• v.10 no.3
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• pp.133-140
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• 2001

This study was conducted to develop a nutrient uptake model in cucumnber (Cucumis sativus L. cv. Eunsung Backdadagi) plants for prediction of the amount of nutrients in drainage solution in a closed perlite culture system. Electrical conductivity (EC) of the nutrient solution was adjusted to 1.5, 1.8, 2.1, 2.4, and 2.7 dS. $m^{-1}$ . The amount of nutrient solution absorbed in different EC treatments was not different until the mid stage of growth. However, after the mid growth stage, a high EC treatment resulted in less solution absorption. The absorption rates of K, N $O_3$$^{[-10]}$ -N, Mg, and P increased continuously for a whole growing period in all treatments, while those of Ca decreased slightly. For S, the decrease was significant after th mid stage of growth. although the amounts of absorbed inorganic ions in different EC treatments were not significantly different at the first stage of growth, they were significantly different after the mid stage of growth and decreased slightly at the end of growth stage. Models for predicting the amounts of each inorganic ion absorbed were developed by using EC and the amount of nutrient solution absorbed per unit radiation(mg.M $J^{-1}$), which proved to be practical with a positive correlation at 1 percent probability between the developed model and practical values..

• Horticultural Science & Technology
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• v.16 no.1
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• pp.25-26
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• 1998

Nutrient supplying by a metering pump often produces the inaccuracy in the rate of inflow than expected. In this study, we developed the transpiration estimation system using the metering pump to measure the continuous supplying rate as well as to estimate the accurate transpiration rate. The system showed the stable characteristics by eliminating the fluctuations in the head loss of nutrient tank. The direct proportionality between the supplying time and the supplied nutrient solution was obtained. The exact correlation between the integrated solar radiation and the transpiration rate using the system was calculated, and correlation coefficients between the two factors were 0.98 in the NFT system and 0.92 in the aggregate system. This results suggest that the integrated solar radiation was an important factor to directly decide the supplying volume of nutrient solution in soilless culture system. The deveolped system using the metering pump in the study was able to control the supply of the nutrient solution to the crops adjusting to the variation of solar radiation.

• Journal of Bio-Environment Control
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• v.8 no.2
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• pp.90-98
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• 1999

This study was conducted to select proper substrate and nutrient solution concentration for favorable growth and quality in common thyme (Thymus vulgaris L.). The growth of common thyme was better in deep flow culture (DFT) than in other substrate cultures. As the nutrient solution concentration rose, the ratio of dry matter increased, while the fresh weight and the number of lateral shoots decreased. The contents of total chlorophyll and vitamin C were higher in DFT than others. Ca, K, P were showed high contents in cocopeat, but Mg content was the highest at half-fold concentration in DFT. Common thyme showed low content of nitrate in DFT compared with that in other substrate culture. DFT was the most effective system for pronoting growth and quality of common thyme. The optimal concentration of nutrient solution in common thyme was half-fold(EC=1.2mS/cm) of herbs nutrient solution by European Vegetable R&D Center.

• Horticultural Science & Technology
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• v.19 no.1
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• pp.92-97
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• 2001

This experiment was conducted to find out optimum substrate and concentration of nutrient solution for mass production of sweet basil by pot culture. Growth depending on concentration of nutrient solution was different to some extent; the growth of plants was usually better in one-fold and two-fold concentration of nutrient solution but three-fold one was poor. Plants grown in cocopeat showed better growth, but peatmoss gave an adverse effect. Sweet basil grown in substrate mixed with cocopeat and perlite (1:1, v:v) was highest in essential oil content. After all, cultural practice by one-fold concentration of herb nutrient solution in substrate mixed with cocopeat and perlite (1:1, v:v) was recommended for better growth and higher essential oil content of sweet basil.

• Korean Journal of Soil Science and Fertilizer
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• v.37 no.3
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• pp.177-183
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• 2004

The discharge of waste nutrient solution from greenhouse to natural ecosystem leads to the accumulation of excess nutrients that results in contamination or eutrophication. There is a need to recycle the waste nutrient solution in order to prevent the environmental hazards. The amount and kind of nutrients in waste nutrient solution might be enough to grow photosynthetic microorganisms. Hence in the present study, we examined the growth and mass cultivation of cyanobacteria in the waste nutrient solution with an objective of removing N and P and concomitantly, its mass cultivation. Four photosynthetic filamentous cyanobacteria (Anabaena HA101, HA701 and Nostoc HN601, HN701) isolated from composts and soils of the Chungnam province were used as culture strains. Among the isolates, Nostoc HN601 performed faster growth rate and higher N and P uptake in the BG-II ($NO_3{^-}$) medium when compared to those of other cyanobacterial strains. Finally, the selected isolate was tested under optimum conditions (airflow at the rate of $1L\;min^{-1}$. in 15 L reactor, initial pH 8) in waste nutrient solution from tomato hydroponic in green house condition. Results showed to remove 100% phosphate from the waste nutrient solution in the tomato hydroponics recorded over a period of 7 days. The growth rate of Nostoc HN601 was $16mg\;Chl-a\;L^{-1}$ in the waste nutrient solution from tomato hydroponics with optimum condition, whereas growth rate of Nostoc HN601 was only $9.8mg\;Chl-a\;L^{-1}$ in BG-11 media. Nitrogen fixing capacity of Nostoc HN601 was $20.9nmol\;C_2H_4\;mg^{-1}\;Chl-a\;h^{-1}$ in N-free BG-11. The total nitrogen and total phosphate concentration of Nostoc HN601 were 63.3 mg N gram dry weight $(GDW)^{-1}$ and $19.1mg\;P\;GDW^{-1}$ respectively. Collectively, cyanobacterial mass production using waste nutrient solution under green house condition might be suitable for recycling and cleaning of waste nutrient solution from hydroponic culture system. Biomass of cyanobacteria, cultivated in waste nutrient solution, could be used as biofertilizer.

• Journal of Bio-Environment Control
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• v.6 no.4
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• pp.277-283
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• 1997

The effect of nutrient concentration and plant growth regulators on rooting of Coleus stem cuttings were investigated. In contrast to sand cutting, the nutrient solution or plant growth regulator treatment increased the root numbers and root length. The concentration of nutrient solution were 1, l/2 and 1/4 strength of the balanced nutrient solution developed by Japanese Horticultural Experimental Station and the highest root growth was obtained from 1/4 strength nutrient concentration. NAA or IBA treatment in culture solution stimulated the rooting and 0.01mg/l of NAA or IBA was effective in root development. Furthermore, days for rooting were shortened and root growth were promoted by mixing nutrient solutions with plant growth regulators and by using cutting with leaves. The rooting of Coleus was observed under microscope and the adventitious root formation initiated at 3 days after cutting with nutrient and auxin mixture.

• Journal of agriculture & life science
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• v.44 no.6
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• pp.23-26
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• 2010

Commercial fibers such as two kinds of micro-fiber, flannel, and cotton were analyzed for their nutrient solution absorption capacity to select hydrophilic mat used for the irrigation management by drainage level sensor in perlite bag culture. The selected mat was evaluated in terms of absorption capacity. Cotton had the highest absorption capacity and was revealed to be the most appropriate for the control system.

• Journal of Bio-Environment Control
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• v.6 no.1
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• pp.1-14
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• 1997

This experiment was conducted to find out the compositions of nutrient solution for closed system in substrate culture of cucumber. Cucumber(Cucumis sativus L. cv. Eunsung baekdadagi) plants were grown in the substrates supplied with the nutrient solutions whose strengths were 1/2, 1, and 3/2 of the original concentration developed by National Horticultural Research Station in Japan. By increasing the nutrient concentrations, plant height decreased but leaf length, leaf width, and leaf number showed little differences. A number of marketable fruit and marketable yield were the highest in the concentration of 1 strength. The nutrient compositions of solution developed for closed system in cucumber substrate culture were N 11.4, P 3.3, K 6.0, Ca 4.5, and Mg 3.5 me.$\ell$$^{-1}$ during the vegetative growth period and N 10.4, P 3.3, K 5.0, Ca 4.5, and Mg 3,5 me.$\ell$$^{-1}$ during the reproductive growth period. To examine the suitability of nutrient solution developed in the above experiment, cucumber plants were grown in the substrates supplied with different solutions and concentrations - Yamasaki's nutrient solution(Yamasaki) of 1 S, nutrient solution of Research Station for Greenhouse Vegetable and Floriculture on the Netherlands(PTG) of 1 S, nutrient solution developed in the above experiment(SCU) of 1/2, 1, and 3/2 S. EC and pH in root zone changed little in the all treatments during growing period. As cucumber plants grew, the concentrations of N, P, and K in root zone decreased but Ca concentration increased. Net $CO_2$ assimilation rate of cucumber leaves was high in SCU of 1 and 3/2 S, and Yamasaki of 1 S. Growth of cucumber plants was the lowest in SCU of 1/2 S.

• Korean Journal of Plant Resources
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• v.11
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• pp.122-123
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• 1998