• Journal of Life Science
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• v.14 no.5
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• pp.778-787
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• 2004

Effect of the microbial product made of Bacillus stearothermophilus DL-3, which was isolated from the soil and identified in this study, and rice bran on microorganisms in soil and growth of lettuce (Red skirt lettuce) and Chinese cabbage (Ga rack new No.1 Chinese cabbage) was investigated. Total numbers of microorganisms in the pot with untreated soil, treated with standard amount of microbial product and treated with double amounts of microbial product for growth of lettuce after 6 weeks were 2.78${\times}$10$^{7}$ CFU/g, 2.72${\times}$10$^{8}$ CFU/g and 3.63${\times}$10$^{8}$ CFU/g. Total numbers of microorganisms in the soil without treatment of microbial product and treated with standard amount of microbial product were 2.06${\times}$10$^{8}$ CFU/g and 5.49${\times}$10$^{8}$ CFU/g. Total numbers of microorganisms in the pot with untreated soil, treated with standard amount of microbial product and treated with double amounts of microbial product for growth of Chinse cabbage after 6 weeks were 1.43${\times}$10$^{7}$ CFU/g, 3.42${\times}$10$^{8}$ CFU/g and 7.22${\times}$10$^{8}$ CFU/g. Total numbers of microorganisms in the soil without treatment of microbial product and treated with standard amount of microbial product were 5.75${\times}$10$^{8}$ CFU/g and 7.96${\times}$10$^{8}$ CFU/g. On basis of leaf length, leaf width, leaf number, wet weight and dry weight, the growth of lettuce and Chinese cabbage on the soil treated with microbial product was faster than that on the untreated soil. The treatment of microbial product in the soil resulted in the increase of useful microorganisms, which seemed to enhance the growth of lettuce and Chinese cabbage.

• Korean Journal of Organic Agriculture
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• v.19 no.spc
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• pp.222-224
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• 2011

The effects of seawater on growth of lettuce(Lactuca sativa L.), leaf perilla(Perilla frutescens var. japonica Hara), red pepper(Capsicum annuum L.) and cucumber(Cucumis sativus L.) seedlings were investigated in the glass greenhouse. These effects were studied on seedlings, and diluted seawater (1%, 5%, 10%, 20%, 50%, 100% v/v) was sprayed enough on leaves. The tested four vegetable crops have well grown up to 10% diluted seawater, but the tested vegetable crops were damaged from increasing salt levels. Of these, lettuce was provided salt-tolerant vegetable crop and red pepper was considered salt-sensitive vegetable crop. The salt tolerance of vegetable crops is different between crops and complicated because of additional detrimental effects caused by accumulated ions or specific ion toxicities in their leaves. These results show that agricultural use of seawater may be benefit crop cultivation in organic farming system as well as in conventional farming system.

• Journal of Food Hygiene and Safety
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• v.20 no.1
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• pp.43-47
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• 2005

This study monitored and compared the contamination levels of total aerobic bacteria, coliforms, Escherichia coli, and L. monocytogenes of either lettuce, sesame leaf, or cucumber sampled from either 15 super markets(SM) or 21 traditional markets(TM) located in both Seoul and the southern part of Gyunggi. Contamination levels of total aerobic bacteria and coliforms in lettuce, sesame leaf, or cucumber from SM or TM were not (p>0.05) significantly different. The highest contamination levels of total aerobic bacteria were observed in lettuce and followed by sesame leaf and cucumber. The contamination levels of total aerobic bacteria in lettuce, sesame leafs, and cucumbers were $7.01{\pm}0.14\;log_{10}CFU/g(SM)$ and $7.10{\pm}0.11\;log_{10}CFU/g(TM)$, $6.69{\pm}0.20\;log_{10}CFU/g(SM)$ and $6.44{\pm}0.13\;log_{10}CFU/g(TM)$, and $5.37{\pm}0.25 \;log_{10}CFU/g(SM)$ and $5.27{\pm}0.19\;log_{10}CFU/g(TM)$, respectively. A similar pattern of contamination rank was observed with the coliforms in three vegetables as was observed with the total aerobic bacteria E. coli were not significantly (p>0.05) different between SM and TM and isolated over $30\%$ in lettuce and sesame leaf and below $10\%$ in cucumbers. L. monocytogenes were not detected in all three vegetables(ND: cucumber <3 CFU/g, lettuce and sesame leaf <10 CFU/g). The microbial contamination levels determined in the present study may be used as the primary data to execute microbial risk assessment of fresh vegetables.

• Journal of Bio-Environment Control
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• v.4 no.1
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• pp.50-58
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• 1995

These studies were carried out to develop a system for non -destructive and continuous measurement of fresh weight and to analyse the growth response of leaf lettuce under the different nutrient solution and light condition with this system. The developed measurement system was consisted of four load cells and a microcomputer. The output from the system was highly positive correlation with the plant fresh weight above the surface of the hydroponic solution. The top fresh weight of plant could be measured within the error $\pm$ 1.0g in the range of 0 - 2000g. The top fresh weight of leaf lettuce increased 44 times at 18th day after transferring to the nutrient solution, and the maximum growth rate was observed at 13th day after transferring. The growth rate was 10.7- 29.6% per day during 18 days. Optimum concentration of the nutrient solution for the growth of lettuce was 1.4 - 2.2 mS/cm of EC level. When the light condition was changed from dark to light, the fresh weight was temporarily decreased, but the fresh weight increased under the opposite condition. Top fresh weight of leaf lettuce in the darkness normally increased within 12 hours after darkness treatment, and then slowly increased until 78 hours under continuous dark condition. After that times, the fresh weight began to decrease.

• Journal of Biosystems Engineering
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• v.25 no.4
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• pp.293-300
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• 2000

Automated greenhouse production system often require crop growth monitoring involving accurate quantification of plant physiological properties. Conventional methods are usually burdensome, inaccurate, and harmful to crops. A thermal image analysis system can accomplish rapid and accurate measurements of physiological-property changes of stressed crops. In this research a thermal imaging system was used to measure the leaf-temperature changes of several crops according to nutrient stresses. Thermal images were obtained from lettuce, cucumber, and pepper plants. Plants were placed in growth chamber to provide relatively constant growth environment. Results showed that there were significant differences in the temperature of stressed plants and non-stressed plants. In a case of the both N deficiency and excess, the leaf temperatures of cucumber were $2^{\circ}C$ lower than controlled temperature. The leaf temperature of cucumber was $2^{\circ}C$ lower than controlled temperature only when it was under N excess stress. For the potassium deficiency or excess stress, the leaf temperaures of cucumber and hot pepper were $2^{\circ}C$ lower than controls, respectively. The phosphorous deficiency stress dropped the leaf temperatures of cucumber and hot pepper $2^{\circ}C$ and $1.5^{\circ}C$ below than controls. However, the leaf temperature of lettuce did not change. It was possible to detect the changes in leaf temperature by infrared thermography when subjected to nutrition stress. Since the changes in leaf temperatures were different each other for plants and kinds of stresses, however, it is necessary to add a nutrient measurement system to a plant-growth monitoring system using thermography.

• Korean Journal of Agricultural Science
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• v.12 no.1
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• pp.128-138
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• 1985

This study was conducted to elucidate the shelf-life and quality changes in relation to biochemical components in leaf lettuce (Lactuca sativa L.). The shelf-life of leaf lettuce at room temperature was 2 to 3 days. But it was extended to 3 weeks by packaging in a 0.01 mm thick polyethylene film sack when stored at $3^{\circ}C$. The ascorbic acid contents of fresh leaf lettuce was 25 mg per 100 gram fresh weight. The acid at room temperature was almost destroyed after 4 days storage. But the contents of ascorbic acid at $3^{\circ}C$ maintained about 50 to 60% of the initial level in packaging of polyethylene film sack after 8 days storage. The content of chlorophyll was greatly decreased at room temperature but no significant changes were found at $3^{\circ}C$. The changes of total sugar and reducing sugar contents during storage were not very different between treatments. The contents of alkali soluble protein and free amino acid gradually increased in the treatments of polyethylene film sack packaging during storage in general, but the contents decreased after the increase in control treatment. Nucleic acid content, peroxidase and polyphenoloxidase activities were measured and discussed in relation to the leaf senescence.

• Journal of Plant Biology
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• v.30 no.1
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• pp.59-67
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• 1987

To verify allelopathic effect of tomato plants a number of labovatory experiments, seed germination and seedling growth with aqueous extracts and leachates form the tomato plants, have performed. Germination percentage of the tested species was decreased by treatment with leaf, stem and root extracts as extracting time elapses. The leaf extract more inhibits the germination of the seeds than both stem and root extracts. Leachate collected from the tomato plants decreases as much as 50% of the growths in elongation as well as dry weight of seedlings of lettuce and egg plant. It is observed that with a paired-plants grown in U tube pot the tomato roots have excreted allelochemicals to inhibit the growth of the tested species and volatile substances from the tomato plants have suppressed to dry weights of lettuce, to elongation and dry weights of grapevine planted near the tomato plants.

• Journal of Environmental Science International
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• v.26 no.1
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• pp.109-118
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• 2017

This study was conducted to investigate the effects of intermittent plasma and electrolysis treatments on lettuce (Lactuca sativa var. oak-leaf.), nutrient solution components ($NO_3{^-}-N$, $NH_4{^+}-N$, $PO{_4}^{3-}-P$, $K^+$, $Ca^{2+}$ and $Mg^{2+}$) and environmental parameters (electrical conductivity, total dissolved solids and pH). The recirculating hydroponic cultivation system consisted of planting port, LED lamp, water reservoir and circulating pump. Nutrient solution was circulated in the following order: reservoir ${\rightarrow}$ filtration-plasma or filtration-electrolysis ${\rightarrow}$ planting port ${\rightarrow}$ reservoir. The results showed that nutrient solution components and environmental parameters were changed by plasma or electrolysis treatment. Lettuce growth was not affected by the intermittent plasma or electrolysis treatment with 30 minutes or 90 minutes, respectively. The roots of the lettuce was damaged by excessive plasma and electrolysis treatment. Electrolysis treatment had greater effect on than plasma treatment because of the accumulation of high levels of TRO (Total Residual Oxidants).

• Journal of Environmental Science International
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• v.33 no.5
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• pp.305-322
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• 2024

The aim of this study was to investigate the effects of artificial light sources on the germination and seedling vigor of lettuce, aiming to identify the optimal artificial light source for producing high-quality seedlings. Lettuce cultivar of 'Tomalin' and 'Seonpunggold' exhibited the highest seed emergence in the Metal halide(MH) lamp and High-pressure sodium(HPS) lamp treatment group, while the emergence rate parameter, T50, was the fastest in the HPS lamp treatment group. Both cultivars showed good growth characteristics such as number of leaves, root length, and stem diameter under RGB-LED, and their seedling vigor was excellent as well. The plant height was smallest in the Red + Green + Blue LED treatment, but the leaves were round and thick, resulting in higher biomass and dry weight. Single light sources of Red LED and Blue LED led to reduced growth compared with that under the mixed light treatments. Chlorophyll content in lettuce varied with the type of artificial light, with both cultivars exhibiting the highest chlorophyll content in the Red + Green + Blue LED treatment. The most suitable artificial light for lettuce seedling growth was the Red + Green + Blue LED treatment.

• Korean Journal of Breeding Science
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• v.41 no.4
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• pp.574-578
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• 2009

A new red leaf lettuce (Lactuca sativa L.) cultivar, "Gopungjeokchukmyeon" which has late bolting and good red expression leaf color was developed from a cross between "Andongjeokchukmyeon" (red leaf color and late bolting) and "Dukseomjeokchukmyeon" (high yield). The cross and selection for advanced lines had been done by the pedigree method during 2000-2006. The advanced lines were evaluated for yield and adaptability at several locations in Korea (Gangwon, Kyunggi, Chungbuk, Kyungnam, Jeonnam, Jeonbuk, and Jeju) from 2007 to 2008. The "Gopungjeokchukmyeon" has gray seed color and traverse elliptic leaves. Compared to "Dukseomjeokchukmyeon", marketable yield of "Gopungjeokchukmyeon" was higher by 17% (at 330 g per plant) and Gopungjeokchukmyeon has particularly improved expression of red leaf color in high temperature cultivation in the field. The shelf-life of "Gopungjeokchukmyeon" was three weeks longer than "Dukseomjeokchukmyeon" at $4^{\circ}C$. The anthocyanin and sugar contents of "Gopungjeokchukmyeon" were higher than those of "Dukseomjeokchukmyeon" with 29.4 mg/100 g and 4.8 brix, respectively. The content anthocynin of "Gopungjeokchukmyeon" is about 10 times higher than those of "seomjeokchukmyeon". Furthermore, its taste is better, more crispy, and sweeter than those of "Dukseomjeokchukmyeon", This new cultivar "Gopungjeokchukmyeon" can be harvested all year around even summer cultivation.