• Journal of Bio-Environment Control
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• v.32 no.3
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• pp.234-241
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• 2023

This study was conducted to investigate the growth of lettuce (Lactuca sativa L.) and Korean mint (Agastache rugosa Kuntze) with microbubble in a closed-type plant production system (CPPS) with a deep flow technique (DFT). Lettuce and Korean mint were grown in CPPS for 23 days. Microbubble was treated for 5 minutes daily at 9:00, 13:00, and 17:00 for 16 days. The leaf length, leaf width, leaf area, and fresh and dry weights of lettuce and Korean mint were significantly lower in microbubble than in the control. The total root length, root surface area, and the number of root tips of lettuce and Korean mint were significantly lower in the microbubble than in the control. In the case of average root diameter, there was no difference between the treatments of lettuce. However, Korean mint significantly increased in thickness in the microbubble treatment, indicating variations among the different crops. The results of the research indicated that microbubble treatment in the DFT inhibited plant growth by inducing abiotic stress in lettuce and Korean mint.

• Journal of Bio-Environment Control
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• v.16 no.4
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• pp.348-351
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• 2007

This study was conducted to find out the change of infernal quality, such as vitamin C and nitrate contents in some leaf vegetables grown hydropoincally in different nutrient conditions. Pak-choi (Brassica camperistis L. spp. chinesis Jusl.), chungchima (Lactuca sativa L. var. crispa cv. Chungchima) and romaine (Lactuca sativa L. var. longifolia Lam.) lettuces were cultivated for 2 weeks in 4 different nutrient solutions, such as tap water; no-nutrient, added $NH_4$, discarded $NO_3$, and supplied Yamazaki' solution for lettuce as a control. The growth of leaf vegetables was not different among nutrient solution treatments except tap water. The nitrate content showed the highest in control, and followed by $+NH_4$ treatment, $-NO_3$ and tap water treatment, regardless of kind of vegetables. The vitamin C content in 3 different vegetables showed the opposite result against nitrate content so that the treatment that showing the highest vitamin C content was tap water in romaine and chungchima lettuces, and $-NO_3$ treatment in pak-choi. The vitamin C and the nitrate content showed high correlations; $r=-0.614^*$ in pak-choi, $-0.651^*$ in romaine lettuce, and $-0.804^{**}$ in chungchima lettuce.

• Journal of Environmental Science International
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• v.28 no.11
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• pp.1019-1025
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• 2019

The aim of this study was to analyze the light traits in a solar light-collector device and its effects on lettuce growth at an early growth stage. The three hyper parameters used were the reflector diameter (2 cm and 4 cm), coating inside the reflector (chrome-coated, non-coated) and distance from the light fiber (15 cm and 20 cm). The results showed that light efficiency, which is the ratio of light intensity inside the fiber to the solar intensity, improved by 41.1 % when using a 2 cm diameter chrome-coated reflector at a distance of 15 cm from the light fiber; whereas it only improved by 20.6% when a non-coated reflector was used. As the reflector size was increased to 4 cm, the light efficiency for the coated and non-coated reflectors increased by 28.5 % and 26.4 %, respectively, hence, no significant difference was observed. When the light fiber was placed at a distance of 20 cm, the increase in light efficiency with coating treatment was 8 % higher than without coating treatment. We also compared the efficiency of light-fiber treatment with that of LED treatment in our lettuce nursery, and observed that the plants exhibited better growth with light-fiber treatment. We observed an average increase of 1.7 cm in leaf height, $7cm^2/plant$ increase in leaf area, and 32 mm increase in root length upon light-fiber treatment as opposed to those observed with LED treatment. These findings indicate that the collector light-fiber is economically feasible and it improves lettuce growth compared with the LED treatment.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.2
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• pp.142-147
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• 2015

The artificial light sources for growth of plant are usually high-pressure sodium lamp, metal haloids lamp, and fluorescent light; however, these light sources have relatively weaker Red and Blue lights that are necessary for growth of plants. Especially the effect of Photosynthetic Photon Flux Density (PPFD) is pointed out as the weakness. Meanwhile, LED light source can be selected by specific wavelength to greatly improve the effect of PPFD. In this regard, this paper aims to investigate the promotion of plant growth by measuring photosynthetic photon flux density (hereafter referred to as PPFD) according to changes in light quality of the LED light sources. Towards this end, LED light sources for plant growth were produced with 4 kinds of mono-chromatic lights and 6 kinds of combined lights by mixing red, blue, green and white lights. A comparative analysis was conducted to investigate the effects of optical properties and PPFD on plants (green leaf lettuce) using the produced light sources. The results monochromatic light has fastest growth rate, but plant growth conditions have poor. This being so, mixed light is suitable for the green leaf lettuce.

• The Korean Journal of Pesticide Science
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• v.19 no.3
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• pp.151-160
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• 2015

This study was conducted to monitor residual pesticides in perilla leaf & lettuce and to assess their risk to human health. The total number of perilla leaf & lettuce were 4,063 and 2,248 respectively and these products were collected at the Garak-dong Agricultural & Marine Products Market sold by auction from 2010 to 2012. Multi-residual analysis of 285 pesticides were performed by GC-ECD, GC-NPD, HPLC-DAD and HPLC-FLD. In perilla leaf, 61 pesticides were detected and detection rate was 20.0%. 28 pesticides were detected in case of lettuce and detection rate was 4.8%. In order to do risk assessment by perilla leaf & lettuce consumption, estimated daily intake of residual pesticides were determined and compared to acceptable daily intake, referring to hazard index (HI values). The range of % HI values of perilla leaf was from 0.000% to 0.049%. The range of % HI values of lettuce was from 0.000% to 0.095%. These results show that the risk caused by pesticide residues in perilla leaf & lettuce intake were very low and these vegetable intake was safe.

• Journal of Environmental Science International
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• v.31 no.5
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• pp.405-411
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• 2022

Production of lettuce under indoor cultivation is highly affected by light intensity. In this study, we used shade cloth (commercial black net) to examine the effect of these condition on growth without an associated yield penalty of container-grown lettuce. Four levels of shading treatments (0%, 35%, 55%, and 75% referred to as Cont., S₃₅, S₅₅, and S₇₅ with respect to Cont.) and two lettuce varieties (red and blue) were evaluated. Variety-specific growth responses were observed with respect to different levels of shading treatments. High growth of red lettuce was occurred in Cont. treatment despite plant height and leaf length being higher than Cont. However, under 35% shading treatment blue lettuce was higher than in control plants. The highest root length was observed 0% shading (Cont.) of both varieties. These results reinforce the idea that blue lettuce is the better leafy vegetable rather than red lettuce for indoor cultivation related to lower light intensity environment conditions.

• Journal of Bio-Environment Control
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• v.25 no.3
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• pp.139-145
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• 2016

The objective of this study was to compare the growth and light use efficiency of red leaf lettuce grown under three types of combined light-emitting diodes (LEDs) and fluorescent lamps (FL) in a closed-type plant production system. The eighteen days-old lettuce seedlings of red leaf lettuce (Lactuca sativa L., 'Jeokchima') were transplanted to the close-type plant production system equipped with three types of combined LEDs with red (R, 655 nm), blue (B, 456 nm), green (G, 515 nm), and white (W, 456 nm + 558 nm) (R:B=8:2, R:W:B=8:1:1, R:G:B=8:1:1) and FL. The seedlings were grown under normal growth conditions ($20^{\circ}C$, $181{\pm}4{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$, 12 h photoperiod) for four weeks. Lettuce plants grown under FL had significantly higher leaf shape index than those under all LED treatments. Although growth of shoots and roots was not show any significant difference among LED treatments, all of the LED treatments induced about 34% higher shoot fresh weight than that of the FL. On the other hands, the total power consumption of FL was 145 kW for 4 weeks, while the mean value of LED treatments was 54 kW, which was about 3 times lower value than that of the FL. The light use efficiency based on dry matter in LED treatments was about 34 mg/W and this was about 3.5 times higher energy saving value than the FL. In conclusion, this study showed that irradiation of optimal combined LEDs in closed-type plant production systems can improve the lettuce growth as well as maximize in light use efficiency through energy saving than the FL.

• Journal of Biosystems Engineering
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• v.24 no.1
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• pp.25-30
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• 1999

The effectiveness of many greenhouse environment control methodologies depends on the growth information of crops. Acquisition of the growth information of crops requires a non-invasive and continuous monitoring method. Crop growth monitoring system using digital imaging technique was developed to conduct non-destructive and intact plant growth analyses. The monitoring system automatically measures crop growth information sends an appropriate control signal to the nutrient solution supplying system. To develop the monitoring system, a linear model that explains the relationship between the fresh weight and the top projected leaf area of a lettuce plant was developed from an experiment. The monitoring system was evaluated buy successive lettuce growing experiments. Results of the experiments showed that the developed system could estimate the fresh weight of lettuce from a lettuce image by using the linear model and generate an EC control signal according to the lettuce growth stage.

• Korean Journal of Organic Agriculture
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• v.15 no.4
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• pp.437-452
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• 2007

From the experiments on the effect of chitosan and wood vinegar, which are environment-friendly materials, on the growth of eggplant and leaf lettuce, the following results were obtained. 1. The effect of chitosan and wood vinegar treatment on the growth of eggplant 1) There was no difference in soil component elements before and after treatment with chitosan and wood vinegar. The total number of microorganisms tended to increase after treatment with chitosan and wood vinegar, while the number of bacteria increased among microorganisms. However, there was no consistent tendency in the number of Acinomycetes, fungi, and trichodema between treatments. 2) The growth and the yield of eggplant increased compared with the control plot in both the chitosan-treated plot and the wood vinegar-treated plot. However, there was no significant difference between the treatments. The yield of eggplant per 10a increased in chitosan- and wood vinegar-treated plots compared with the controlled plot. There was no significant difference in treatments, however, the plot treated with 800 times-diluted solution showed a higher growth. 2. The effect of chitosan and wood vinegar treatment on the growth of leaf lettuce 1) There was no difference in soil component elements before and after treatment with chitosan and wood vinegar. The number of bacteria increased among microorganisms. However, there was no consistent tendency in the number of Acinomycetes, fungi, and trichodema between treatments. 2) The growth of leaf lettuce in both chitosan-treated plot and wood vinegar-treated plot increased compared with the control plot, however, there was no significant difference between the treatments. On the whole, the plot treated with greater concentration showed a higher growth.

• Journal of Practical Agriculture & Fisheries Research
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• v.19 no.1
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• pp.5-14
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• 2017

This study was conducted to investigate the effects of nutrient solution strength on growth and nutrient element concentrations in leaf lettuce (Lactuca sativa L. cv. 'Dduksum') by hydroponic culture under fluorescent lamp and LED. Leaf lettuce were grown in closed hydroponic cultivation systems supplied with 1/2, 1 and 2 strength of nutrient solution recommended by horticultural experiment station in Japan. The growth of 'Dduksum' was highest in the 2 strength of standard nutrient solution. The amount of nutrient element in the recycled nutrient solution was higher at 2, 1 and 1/2 strength of nutrient solution. The concentration of NO₃-N, Ca²⁺, Mg²⁺ in the recycled nutrient solutions increased in 1 and 2 strength of nutrient solution but that of NH₄-N decreased gradually in 1/2 and 1 strength of nutrient solution. The concentration of K, Ca, Mg in leaf lettuce was maintained in the normal range, whereas the concentration of phosphorous was 1.3 to 1.6%, which was higher than proper range. As the concentration of NH₄-N decreases gradually in all the treatments, it is necessary to raise the rate of NH₄-N or add it.