• Journal of Bio-Environment Control
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• v.7 no.1
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• pp.71-77
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• 1998

The root-zone environment is an important factor to the plant growth and it is closely related to the thermal characteristics of the root media. In this study thermal characteristics of root media with ambient environmental conditions were analyzed. The temperatures of nutrient solution as well as inside air of culture bed were measured in Nutrient Film Technique(NFT) and Deep Flow Technique(DFT) systems, and also the temperatures of root media measured in aggregate culture systems , The temperature of nutrient solution of NFT system with as low as 3$\ell$/min of flow rate was 3$^{\circ}C$ higher than that with 5 $\ell$/min of flow rate in the daytime, and the temperature of inside air was 2$^{\circ}C$ higher at night. And the temperature of nutrient solution of DFT system with as low as 0.8 cm of water level was 1-2$^{\circ}C$ higher than that with 1 8 cm in the daytime, and the temperature of inside air was almost same at night. The root-zone temperatures in the perlite and rockwool granulate systems with film mulching were 3$^{\circ}C$ higher than those without film mulching in the daytime. However, the rockwool slab system with film mulching showed the same trend as rockwool granulate system, but relatively higher temperature than any other medium because of the exposure of media surface to the ambient air. Additionally the temperature below the plant was measured 3$^{\circ}C$ lower than that between plants.

• Proceedings of the Korean Society for Bio-Environment Control Conference
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• 2001.04b
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• pp.81-85
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• 2001

작물은 빛으로부터 에너지를 공급받아 동화산물을 합성하고 이로부터 각종 대사작용에 필요한 물질을 생산한다. 따라서 빛은 작물이 생육하는데 있어 중요한 환경요인이지만 작물생육에 영향을 미치는 광량, 광질 및 일장 등은 장소, 시간 또는 시설물의 피복재료에 따라 변하기 때문에 이러한 요인들을 고려한 자연광의 효율적 이용은 시설재배 작물의 생장과 발육에 중요한 의미를 갖는다. (중략)

• Korean Journal of Plant Resources
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• v.20 no.1
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• pp.69-72
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• 2007

This study was performed to determine the effect of nutritional concentrations and fertilization intervals on growth of native pteridophyte (Pteris multifida, Cyrtomium falcatum, Cheilanthes argentea). Nutrient concentrations were treated with non-treat, 500X, 1,000X and 2,000X solution, and fertilization periods were treated in everyday, 5, 10 and 20day respectively, under the 30% shading net. Pteris multfida appeared to be very good for growth by fertilizing at intervals of 10 day with nutrient concentration of 2,000X drainage solution. The growth of Cyrtomium falcatum was the best in the treatment of $1,000{\sim}2,000X$ concentration for 10 days while that of Cheilanthes argentea was the highest in the treatment of 1,000X concentration for 5days.

• Journal of Bio-Environment Control
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• v.10 no.2
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• pp.95-100
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• 2001

In countries that consumes rice as a main staple, rice hulls are natural resources composed of a large amount of organic compounds and high uniformity in size. Rice hulls are expanded to get rid of a defect in untreated rice hulls and to be used as a hydroponic substrate. Research on rice hulls is continuing for the agricultural application. This research was conducted to stabilize rhizosphere pH of the expanded rice hull substrates because of high pH caused by repeated use in ERH(expanded ride hull) substrates and without increasing the cost of developing new substrates. Sphagnum peatmoss (pH 3.0-4.0) wee mixed with the expanded rice hull substrate in the ratio of 10% (v/v), and this ratio kept the pH range of 6.0 to 6.5 in the root area of tomato plants during growth and at the time of harvest of tomato fruits. Also absorbtion of nutrients was highly increased. The yield increased from 1,051 to 1,266 kg per tomato plant which were harvested by two clusters.

• Journal of Biosystems Engineering
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• v.20 no.4
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• pp.390-396
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• 1995

This study was conducted to develop a computer simulation program for trickle application of nutrient solution. A computer simulation program using finite element method was developed to evaluate discharges of emitters on trickle application. The uniformity of application for two different lateral line lengths and three application methods was evaluated by the computer simulation program. The results of this study are as follows. 1. A computer simulation program was developed to determine emitter discharges from a trickle application system and pressures at emitter positions by finite element method and to design a uniform trickle application system. 2. The simulation program developed was verified by experiment. The root mean square error between experimental data and simulated data was 1.1% on the average discharge and it was found that the computer simulation program was an effective tool for the design of a trickle application system of nutrient solution. 3. The uniformity of trickle application system was evaluated for three different methods of supplying nutrient solution with different lateral line lengths. The best uniformity was obtained from the method, which supplies nutrient solution from both ends alternatively for the same period of time.

• Journal of Biosystems Engineering
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• v.23 no.4
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• pp.365-372
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• 1998

This study was carried out to develop a nutrient-solution mixing-and-supplying system, which used a low-cost metering device instead of expensive metering pumps and a fuzzy logic controller. A low cost and precise overflow-type metering device was developed and evaluated by testing the flow discharge for the automatic nutrient-solution mixing-and-supplying system for snail-scale hydroponic sewers. The fuzzy logic controllers, which could predict and meet the desired values of EC and supply rate of nutrient solution were developed and verified by simulation and experiment. this fuzzy logic controller, whose algorithm consists of four crisp inputs, two crisp outputs and nine rules, was developed to predict the desired value of EC and supply rate of nutrient solution and two crisp inputs, one crisp output and nine rules used to control EC to the desired values. The nutrient-solution mixing-and-supplying system showed satisfactory EC control performance with the maximum overshooting of 0.035 mS/cm and the maximum settling time of 15 minutes in case of increasing 0.7 mS/cm. also, the accuracy of the overflow-type metering device in terms of the full-scale error was 2.29% when using solenoid valve only and 0.2% when using solenoid valve and flow control valve together.

• Journal of Bio-Environment Control
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• v.23 no.4
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• pp.364-370
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• 2014

The nutrient and irrigation management of scion and rootstock can alleviate stress on grafted transplants after grafting and promote the growth. This study investigated the effects of nutrient and irrigation management of scion and rootstock on the graft-take and growth of grafted pepper transplants. Before grafting, the scions were subjected to different water potential regimes in media by controlling the irrigation frequency and time. The scions were subirrigated 0, 1(two days before grafting), 1(one days before grafting) or 2 times for five days before grafting. The irrigation frequency and time influenced the water potential of media and the growth of scion and grafted transplants. At 13 days after grafting, fresh and dry weight of transplants which were irrigated once at two days before grafting were greater by 29 and 34% than those without irrigation during five days before grafting. This suggests that mild water stress on scion prior to grafting by controlling water management alleviate water stress on grafted transplants after grafting and improve the growth. Before grafting, the rootstocks were subjected to different nutrient regimes by controlling nutrient solution application. The rootstocks were supplied with nutrient solution 0, 1, 2, or 4 times. The nutrient application frequency and time influenced the electrical conductivity (EC) and pH of media. Accordingly, the growth and mineral contents of rootstock and grafted transplants were also affected. At 13 days after grafting, fresh and dry weight of transplants with four times of nutrient application increased by 30 and 20%, respectively, than those without nutrient solution supply during seven days before grafting. Therefore, it is recommended that nutrient solution be supplied more than four times during seven days before grafting for the production of high quality transplants.

• Journal of Bio-Environment Control
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• v.8 no.2
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• pp.75-82
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• 1999

This study was carried out to examine the effect of day/nignt temperatures during seedling culture on the vegetative and reproductive growth of Lycopersicum esculentum ‘Seokwang’. The study was consisted of two culture stages, plug seedling production in the growth chamber and hydroponic culture of the plant in a glasshouse. Experiments were replicated over time. The germinated seedlings were raised for 33 days (experiment 1) and 35 days (experiment 2) in 4 growth chambers, each with day/night temperatures of either $25^{\circ}C$/$25^{\circ}C$, 16$^{\circ}C$/16$^{\circ}C$, 16$^{\circ}C$/$25^{\circ}C$ or $25^{\circ}C$/16$^{\circ}C$. Cool-white fluorescent lamps provided 140$\mu$mol.m$^{-2}$ .s$^{-1}$ light for 12h each day. In the second experiment, all chambers were supplied with 1000$\mu$mol.mol$^{-1}$ CO$_{2}$ during the photoperiod and had an air velocity of 0.3m.s$^{-1}$ and relative humidity of 80%. Plug seedlings raised were transplanted to rockwool slabs in a glasshouse and were grown hydroponically using the same nutrient solutions used for seedling culture for 37 days (experiment 1) and 35 days (experiment 2). Plant height was affected more by mean daily temperature than by interaction of day and night temperatures. Plant height was the highest in 16/16$^{\circ}C$ treatment. Leaf count was not affected by day and night temperatures, and the chlorophyll concentration was the highest in 16/$25^{\circ}C$ treatment. Fresh and dry weights of stem tended to be greater in treatments of constant day and night temperature. The number of node on which first and second flower clusters were set was significantly higher in 25/$25^{\circ}C$ treatment than in the other treatments. Days to flower of the first flower on the first flower cluster were the greatest in 25/$25^{\circ}C$ and the least in 16/$25^{\circ}C$ treatment. Vegetative and reproductive growth, such as height, fresh and dry weights, days to flower, and nodes of the 1st and 2nd flower cluster set were affected by day/night temperatures.

• Proceedings of the Korean Society for Bio-Environment Control Conference
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• 1995.10a
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• pp.87-88
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• 1995

양액재배에서는 토양재배와는 달리 $CO_2$ 농도의 급격한 감소가 나타나게 된다. 또한 엽채류는 질소 공급원에 대한 생육 반응이 민감하며, 그 양상도 다양하게 나타므로 배양액의 NO$_3$ : NH$_4$ 비는 작물의 생육, 수량, 품질 등에 큰 영향을 미치게 된다. 본 실험은 결구상추의 수경재배에서 $CO_2$시용에 따른 질소동화 촉진작용을 검토하고, 배양액 내 질소원의 형태별 비율이 작물생육에 미치는 영향을 구명하여, 결구 상추의 생산성을 극대화하고자 실시하였다. (중략)

• Journal of Bio-Environment Control
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• v.32 no.1
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• pp.23-33
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• 2023

Sucrose (suc) is a disaccharide that consists of glucose (glu) and fructose (fru). It is a carbohydrate source that acts as a nutrient molecule and a molecular signal that regulates gene expression and alters metabolites. This study aimed to evaluate whether suc-specific signaling induces an increase in bioactive compounds by exogenous suc absorption via roots or whether other factors, such as osmotic stress or biotic stress, are involved. To compare the osmotic stress induced by suc treatment, 4-week-old cultured mugwort plants were subjected to Hoagland nutrient solution with 10 mM, 30 mM, and 50 mM of suc or mannitol (man) for 3 days. Shoot fresh weight in suc and man treatments was not significantly different from the control. Both man and suc treatments increased the content of bioactive compounds in mugwort, but they displayed different enhancement patterns compared to the suc treatments. Mugwort extract treated with suc 50 mM effectively protected HepG2 liver cells damaged by ethanol and t-BHP. To compare the biotic stress induced by suc treatment, 3-week-old mugwort plants were subjected to microorganism and/or suc 30 mM with Hoagland nutrient solution. Microorganisms and/or suc 30 mM treatments showed no difference about the shoot fresh weight. However, sugar content in mugwort treated with suc 30 mM and microorganism with suc 30 mM treatment was significantly higher than that of the control. Suc 30 mM and microorganism with suc 30 mM were effective in enhancing bioactive compounds than microorganism treatment. These results suggest that mugwort plants can absorb exogenous suc via roots and the enhancement of bioactive compounds by suc treatment may result not from osmotic stress or biotic stress because of microorganism, but by suc-specific signaling.