• Journal of the Korean Wood Science and Technology
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• v.49 no.4
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• pp.384-393
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• 2021

Recently, due to environmental and toxicity issues, there has been increasing attention on research regarding natural products that can reduce the use of chemical fertilizers. Wood extracts derived from the biorefining process contain various fertilizer ingredients. HPLC analysis revealed that wood extract contains approximately 5.2% hemicellulosic sugar. The growth of lettuce (Lactuca sativa) upon treatment with wood extract (extract obtained from steam-exploded pine) or water-soluble fertilizers containing different nutrients was analyzed in this study. After two weeks, the growth characteristics of lettuce as affected by wood extract or water-soluble fertilizers were significantly different. The effect of water-soluble fertilizers containing ascorbic acid, magnesium sulfate, citric acid, potassium nitrate, amino acids, or seaweed extract was less desirable than that of wood extracts regarding plant height (18.6 cm), number of leaves (10), leaf length (14.1 cm), shoot fresh wight (9.8 g/plant), root fresh weight (0.8 g/plant) and shoot dry weight (0.6 g/plant). The plant height, number of leaves, leaf length, shoot fresh wight, root fresh weight, shoot dry weight of water-soluble fertilizers containing wood extract were significantly different compared to the control (plant height :13.5 cm, number of leaves : 7, leaf length : 9.4 cm, shoot fresh wight : 5.3 g/plant, root fresh weight : 0.7 g/plant, shoot dry weight : 0.4 g/plant, root dry weight : 0.07 g/plant). From these results, it was concluded that wood extract can be used as a potential water-soluble fertilizer to increase the yield of leafy vegetables.

• Korean Journal of Environmental Agriculture
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• v.41 no.3
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• pp.191-198
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• 2022

BACKGROUND: Plants can be grown using a culture medium without soil using a hydroponic system. Crop production by the hydroponic system is likely to increase as a means of solving various problems in the agricultural sector such as aging of rural population and climate change. Different water sources can be used to prepare the culture medium used in the hydroponic system. Therefore, it is necessary to study the effect of different water sources on crop production by the hydroponic system in order to explore the applicability of various water resources. METHODS AND RESULTS: Lettuce was cultivated by the hydroponic system and three different water sources [tap water (TW), bottled water (BW), and groundwater (GW)] were used to compare the effect of water sources on lettuce growth. The three kinds of waters with a nutrient solution (TW-M, BW-M, GW-M) were also used as the media. After the six-week growth period, the lettuce length and weight, the number of leaves, and the contents of chlorophylls and polyphenols were compared among the different media used. The lettuces did not grow in the waters without the nutrient solution. In the media, the lettuce growth and the contents of chlorophylls were affected by the different water sources used to prepare the media, while the contents of polyphenols were not affected. The absorbed amounts of ions by lettuces, especially Ca and Zn ions, and the dry weight of the harvested lettuces showed a strong positive correlation. CONCLUSION(S): Overall, this study shows that different water sources used for growing lettuce in a hydroponic system can affect lettuce growth. Further studies on the enhancement of crop qualities using different water sources may be required in future studies.

• Journal of Plant Biology
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• v.18 no.1
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• pp.1-10
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• 1975

Development of a model system for mode of action studies of $SO_2$ was attempted with a plant tissue. Leaf disks, 1.0cm diameter, cut from the lamina of lettuce leaves, were floated on the testing medium and placed in light or dark condition to investigate the discoloration pattern with various sources of $SO_2$. Discoloration of leaf disks tended to be more serious with higher concentrations of $SO_2$ and on exposure to the light. Leaf disks were more severely discolored at lower pH with constant SO2 concentration. These discoloration patterns were highly reproducible and similar in all sources of $SO_2$. Spectrophotometric evidence suggested that light-mediated discoloration of leaf disks in the presence of $SO_2$ might occur mainly through chlorophyll ${\alpha}$ degradation.

• Journal of Bio-Environment Control
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• v.21 no.3
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• pp.180-185
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• 2012

The objective of this study was carried out to elucidate the effect of LEDs (light emitting diodes) irradiation in relation to early growth and inorganic elements in leaf lettuce (Lactuca sativa L. 'Rollo Rosa'). In morphological changes of leaves, shoot elongation and hypocotyl length showed poor growth in red light irradiation, while the red + blue light irradiation induced shorter plant height and much greater leaf numbers resulting in increased fresh weight. In change of the Hunter's color and SPAD values, lettuce seedlings grown under in red + blue and fluorescent light irradiation had a higher $a^*$ value, otherwise SPAD values were not changed in these light irradiations. Interestingly, relative chlorophyll contents showed 1.8 times increased redness in the treatment of red + blue light irradiation. Inorganic element (N, Ca, Mg, Mn, and Fe) and ascorbic acid contents were increased in lettuce plants grown under LEDs light irradiation compared to those of lettuce grown under the fluorescent light which showed higher P and Mn contents. In conclusion, it is considered that red + blue light irradiation which stimulates growth and higher nutrient uptake in leaf lettuce could be employed in containers equipped with LEDs.

• Korean Journal of Organic Agriculture
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• v.21 no.4
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• pp.659-668
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• 2013

The objective of this study was carried out to elucidate the effect of LEDs (light emitting diodes) irradiation in relation to early growth and inorganic elements in leaf lettuce (Lactuca sativa L. 'Chung Chi Ma'). In morphological changes of leaves, shoot elongation and hypocotyl length showed poor growth in red light irradiation, while the red+blue light irradiation induced shorter plant height and much greater leaf numbers resulting in increased fresh weight. In change of the Hunter's color and SPAD values, lettuce seedlings grown under in red+blue and fluorescent light irradiation had a higher $a^*$ value, otherwise SPAD values were not changed in these light irradiations. Interestingly, relative chlorophyll contents showed 1.8 times increased redness in the treatment of red+blue light irradiation. Inorganic element (N, Ca, Mg, Mn, and Fe) and ascorbic acid contents were increased in lettuce plants grown under LEDs light irradiation compared to those of lettuce grown under the fluorescent light which showed higher P and Mn contents. In conclusion, it is considered that red+blue light irradiation which stimulates growth and higher nutrient uptake in leaf lettuce could be employed in containers equipped with LEDs.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.59 no.4
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• pp.532-538
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• 2014

Arsenic (As) is nonessential element toxic to plants. In Korea little is not only known about the extent of actual anthropogenic sources and inputs of arsenic to the agricultural land which plays a active role as a sink, but also systematic research on arsenic as an toxic element entering the food chain via the soil-plant pathway has not been investigated in the fields and greenhouses besides in few places of abandoned mining sites. Therefore, it is important to focus on the effect of As-contaminated soils on As uptake and biomass production of lettuce plants. In this study, As concentrations in the soil and accumulation of As in lettuce transferred by As uptake from soils were investigated. To do this, soil which was mixed with various rates of arsenopyrite gravels containing arsenic from 0 to 100% was packed into a round plastic pot. Then, 10 days old vegetable crops of chinese cabbage and lettuce after germination were transplanted into a pot. Growth of lettuce was observed for four weeks with one week interval. All experiments were done by triplicate. The results showed that the growth rates for number of leaves, width and length of the crop plants were retarded with increasing amount of gravel mixed due to increasing bioavailable amount of arsenate with increasing rate of gravel in soils. With these results, we conclude that the bioavailable amount of arsenate can influence the growth of lettuce.

• Journal of Bio-Environment Control
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• v.18 no.4
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• pp.303-308
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• 2009

This study was conducted to analyze the feasibility of plant growth under low pressure and to investigate the effect of pressure on plant growth. Three levels of pressures (25, 50, and 101.3 kPa (control)) were provided to analyze the growth of Lettuce (Lactuca sativa L.) as affected by low pressure. Photoperiod, air temperature, and photosynthetic photon flux were set at 16/8 h, 26/$18^{\circ}C$, and $240{\mu}mol{\cdot}m^{-2}s^{-1}$, respectively. Growth characteristics of lettuce were measured on 7 days and 14 days after experiment. Leaf length, leaf width, leaf area, and root dry weight of lettuce measured on 7 days under 25 and 50 kPa were significant as compared to the control. Leaf length, top dry matter and root dry matter of lettuce measured on 14 days were significantly different under 25 and 50 kPa. From these results, we confirmed that lettuce could be grown under low pressure. However high relative humidity by evapotranspiration from leaves and growing beds under low pressure caused the condensation on the inner surface of the chamber. Therefore in a low pressure chamber, humidity control is required to maintain the relative humidity at a proper level.

• Journal of Life Science
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• v.24 no.2
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• pp.148-153
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• 2014

The objective of this study was to elucidate the effect of light-emitting diode treatment on early growth and inorganic elements in leaf lettuce (Lactuca sativa L. 'Oak Leaf'). In changes to leaf morphology, shoot elongation and hypocotyl length showed poor growth under red light irradiation, while red+blue light irradiation induced shorter plant height and more leaves, resulting in increased fresh weight. With respect to Hunter's color and SPAD values, lettuce seedlings grown under red+ blue and fluorescent light irradiation had a higher $a^*$ value but showed no other changes to SPAD values. Interestingly, redness in relative chlorophyll content was 1.4 times higher under red+blue light irradiation. Inorganic element (N, Ca, Mg, and Fe) and ascorbic acid concentrations increased in lettuce plants grown under LED light irradiation compared to those of lettuce grown under fluorescent light, which showed a higher P content. In conclusion, red+blue light irradiation, which stimulates growth and higher nutrient uptake in leaf lettuce, could be employed in containers equipped with LEDs.

• Korean Journal of Environmental Agriculture
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• v.39 no.4
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• pp.375-383
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• 2020

BACKGROUND: Bisphenol A (BPA) is a chemical widely used in polycarbonate plastics, epoxy resins. BPA is an endocrine disruptor. Residue of BPA in agricultural environments is a major concern. The objective of this study was to understand the characteristics of the uptake and distribution of BPA and its metabolites introduced into the agricultural environment to crops, and to use it as basic data for further research on reduction of BPA in agricultural products. METHODS AND RESULTS: This study established the analysis method of BPA and its metabolites in soil and crops, and estimated the intake of BPA and its metabolites from lettuce (Lactuca sativa) grown in sandy loam and loam soil, which are representative soils in Korea. The two major metabolites of BPA were 4-hydroxyacetophenone (4-HAP) and 4-hydroxybenzoic acid (4-HBA). BPA, 4-HAP and 4-HBA have been analyzed by using liquid chromatography tandem mass spectrometry (LC-MS/MS). These substances were detected in sandy loam and loam soil, indicating that certain portions of BPA were converted to 4-HAP and 4-HBA in the soil; however, it was observed that only 4-HBA migrated to lettuce through the roots into crops. CONCLUSION: The uptake residues showed the BPA and 4-HAP were not detected in lettuces grown on sandy loam (SL) and loam (L) soil treatments that were applied with of 10 ng/g, 50 ng/kg and 500 ng/g of BPA. However, the 4-HBA was detected at the level of 7 ng/g and 11 ng/g in the lettuce grown in sandy loam and loam soil that were treated with the 500 ng/g of BPA, respectively, while the 8 ng/g of 4-HBA was measured in the lettuce cultivated in the loam that was treated with 100 ng/g of BPA. This result presents that the BPA persisting in the soil of the pot was absorbed through the lettuce roots and then distributed in the lettuce leaves at the converted form of 4-HBA, what is the oxidative metabolite of BPA.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2003.10a
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• pp.103.1-103
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• 2003

An antagonistic bacteria, Stenotrophomonas maitophilia BW-13 strain which was effectively inhibited mycerial growth of Bottom rot pathogen, Rhizoctonia solani PY-1 strain was isolated from the rhizosphere of the lettuce in Uiryeong-Gun, Gyeongsangnam-Do from 2002 to 2003. For the biological control, the most suitable inoculum and its density of pathogen, PY-1 strain ware tested prior biological control test, For the pathogenicity test, A inoculum (wheat bran)sawdust+rice bran+PDB) showing disease incidence of 100％ was selected as the most suitable inoculum, which showed more effective than B inoculum (sawdust＋rice bran＋DW) and mycelial disc. also, In selection of the amount of inoculum (40g, 50g, 60g, 70g, 80g), most suitable amount of inoculum of pathogen determined as 40g showing disease incidence of 80％. For the selection of effective microorganism to control bottom rot on lettuce, about 200 isolates were isolated from the diseased soil and lettuce leaves, and examined their antifungal activity to the pathogen on PDA. As the pots assay, BW-13 strain showed the highest control value as 90％, and followed by R-13 and R-26 strain as 80％ and 60％, respectively. Selected BW-13 isolates identified as 5. maltophilia (GeneBank accession no. AJ293473.1, 99％) by 16S rRNA sequencing. This is the first report on the biological control using by S. maltophilia to the bottom rot pathogen, Rhizoctonia solani PY-1 strain.