• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2001.07a
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• pp.293-299
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• 2001

• Journal of Bio-Environment Control
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• v.22 no.1
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• pp.65-72
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• 2013

This study was conducted to investigate the influences of bicarbonate ($HCO_3^-$) concentrations in irrigation solution on growth of lettuce and change in chemical properties of root media. The blue leaf and red leaf lettuces with two true leaf stages were transplanted into 10 cm diameter plastic pots filled with perlite. The five treatments were made by dissolving $NaHCO_3$ into irrigation solution to reach 30, 70, 110, 150 and $180mg{\cdot}L^{-1}$ $HCO_3^-$. The crops were fed with fertilizer solution contained $HCO_3^-$ with various concentrations and controlled to $100mg{\cdot}L^{-1}$ in nitrogen concentration. The pH in soil solution of root media 10 weeks after transplant of blue lettuces were 7.04 and 7.10 in the treatments of 30 and $70mg{\cdot}L^{-1}$ of $HCO_3^-$, respectively. But those rose gradually after week 3 and finally reached 7.39, 7.48 and 7.56 at week 10 in the treatments of 110, 150 and $180mg{\cdot}L^{-1}\;HCO_3^-$, respectively. The pH in the treatments of 30 and $70mg{\cdot}L^{-1}\;HCO_3^-$ in cultivation of red leaf lettuce were around 6.65 during week 4 to week 8, but this rose abruptly and reached 6.92 and 7.01 at week 10, respectively. Those in the treatments of 110, 150, and $180mg{\cdot}L^{-1}\;HCO_3^-$ rose gradually and finally reached to 7.49, 7.53, and 7.58, respectively. The EC rose gradually after week 2 in all treatments of blue and red leaf lettuces. The change of macro ion concentrations in both blue and red leaf lettuces showed similar trends. The concentrations of $PO_4-P$, $Ca^{2+}$ and $Mg^{2+}$ increased gradually in all treatments of $HCO_3^-$ during cultivation of blue and red leaf lettuces. As the concentrations of $HCO_3^-$ in irrigation solution were elevated, the concentrations of $PO_4-P$, $Ca^{2+}$ and $Mg^{2+}$ became higher and that of ${SO_4}^{-2}$ became lower in soil solution of root media. The main reason of concentration changes were that $HCO_3^-$ influenced pH and the pH changes also affect the activities of the ions in soil solution of root media.

• Journal of Plant Biotechnology
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• v.35 no.2
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• pp.115-120
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• 2008

L-Ascorbic acid (vitamin C) in vegetables is an essential component of human nutrition. The objective is to transform lettuce (Lactuca sativa L.) with GalUR gene that is involved in the vitamin C biosynthesis. The cotyledons of Hwoahong (Nongwoo Bio Co.) were used to induce the callus and shoot under the selection media with MS + 30 g/L Sucrose + 0.5 mg/L BAP + 0.1 mg/L NAA + 100 mg/L kanamycin + 200 mg/L lilacillin, pH 5.2. The shoot was developed from the cut side of the explants after 3 weeks on the selection media. We successfully transformed the lettuce with GaIUR gene and analyzed the levels of vitamin C. We found that some of the lettuce transgenic lines contained higher levels of vitamin C compared with the normal one (non-transformed). Especially, some of $T_1$ lettuces inserted by GalUR showed about $3{\sim}4$ times higher content of vitamin C compared to the non-transformed lettuce. This data support the previously work performed with GLOase transgenic $T_1$ lettuces from which several times higher content of vitamin C were identified. The $T_2$ lettuces with high content of vitamin C have been selected for further analysis.

• Research in Plant Disease
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• v.16 no.2
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• pp.136-140
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• 2010

Pectobacterium carotovorum subsp. carotovorum causes soft rot disease in diverse plants. Carocin D is bacteriocin that is produced by Pectobacterium carotovorum subsp. carotovorum Pcc21 strain. Nonpathogenic mutant P. carotovorum subsp. carotovorum Pcc21-M15 strain was obtained by mutagenesis with Tn5 insertion and screened pathogenesity. P. carotovorum subsp. carotovorum Pcc21-M15 and E. coli (pRG3431), carocin D gene-transformed E. coli, produce carocin D against P. carotovorum subsp. carotovorum Pcc3. Pathogenic P. carotovorum subsp. carotovorum Pcc3 and mixture with Pcc21-M15 or E. coli (pRG3431) were treated with lettuces. Pcc21-M15 and E. coli (pRG3431) effectively suppressed the development of soft-rot disease. While symptoms in 90% of Pcc3-treated lettuces were observed after 3 days, only 25% of Pcc3 and Pcc21-M15-treated lettuces were observed to be infected after 6 days. These results suggest that the nonpathogenic strain P. carotovorum subsp. carotovorum. Pcc21-M15 and E. coli (pRG3431) are effective to soft-rot disease suppression.

• Korean Journal of Environmental Agriculture
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• v.21 no.2
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• pp.102-108
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• 2002

In order to investigate the mechanism of growth inhibition by salt stress, lettuces were grown hydroponically in three different nutrient solutions, normal and 30 mM or 50 mM $KNO_3$-added nutrient solutions, and the electrical conductivities of these solutions were 1.0, 4.5, and 6.5 dS/m, respectively. The activities of plasma and vacuolar $H^+$-ATPases in the root tissue of lettuce were measured by specific inhibitors, 100 ${\mu}M$ vanadate and 50 mM $NO_3^-$, respectively. Microsomal ATPase activity of lettuce grown in the normal nutrient solution was $356\pm1.5$ nmol/min/mg protein. When lettuces were grown in 30 mM and 50 mM $KNO_3$-added nutrient solutions, total activities of microsomal ATPases were increased by 1.6 and 1.9 times, respectively, and the increases were mainly mediated by vacuolar $H^+$-ATPase. These results show that lettuces adapt themselves to salt-stressed condition by increasing the activities of $H^+$-ATPases. Effects of various heavy metal ions were investigated on the microsomal ATPases and various metal ions at 100 $\mu M$ inhibited the activities by 10$\sim$25%. $Cu^{2+}$ showed the highest inhibitory effect on the vacuolar $H^+$-ATPase. These results suggest that lettuce increases the activities of root ATPases, specially that of vacuolar $H^+$-ATPase, in salt-stressed growth conditions and $Cu^{2+}$ could be a useful tool to control the activity of vacuolar $H^+$-ATPase.

• Korean Journal of Environmental Agriculture
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• v.20 no.1
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• pp.28-33
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• 2001

Lettuces were grown hydroponically in three different nutrient solutions, normal and 30 or 50 mM $KNO_3-added$ nutrient solutions, and the electrical conductivities of the nutrient solutions were 1.0, 4.5, and 6.5 dS/m, respectively. Lettuces grown in the $KNO_3-added$ nutrient solutions showed a decrease in the germination ratio and the lower indices of growth, such as plant height, stem diameter, leaf length, and leaf width. Microsomes were prepared from the roots of lettuce and characteristics of microsomal ATPases were investigated. The activities of microsomal ATPases grown in the 30 mM and 50 mM $KNO_3-added$ nutrient solutions were higher than that grown in the normal nutrient solution. The highest activities of microsomal ATPases were observed at pH 7.0 in all culture conditions. The activities of microsomal ATPases were increased in a reaction buffer solution containing high concentration of $K^+$, whereas they were decreased in a reaction buffer containing $Na^+$. The stimulating effect of $K^+$ in the reaction buffer was greater on the microsomal ATPases of lettuces grown in the $KNO_3-added$ nutrient solutions than that grown in the normal nutrient solution. These results imply that the activities of microsomal ATPases in the root tissue are increased as increasing the $KNO_3$ concentration in the hydroponical nutrient solution.

• 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 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 Biosystems Engineering
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• v.21 no.3
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• pp.315-324
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• 1996

This study was one of a series of studies on application of machine vision and image processing to extract the geometrical features of plants and to analyze plant growth. Several algorithms were developed to measure morphological properties of plants and describing the growth development of in-situ lettuce(Lactuca sativa L.). Canopy, centroid, leaf density and fractal dimension of plant were measured from a top viewed binary image. It was capable of identifying plants by a thinning top viewed image. Overlapping the thinning side viewed image with a side viewed binary image of plant was very effective to auto-detect meaningful nodes associated with canopy components such as stem, branch, petiole and leaf. And, plant height, stem diameter, number and angle of branches, and internode length and so on were analyzed by using meaningful nodes extracted from overlapped side viewed images. Canopy, leaf density and fractal dimension showed high relation with fresh weight or growth pattern of in-situ lettuces. It was concluded that machine vision system and image processing techniques are very useful in extracting geometrical features and monitoring plant growth, although interactive methods, for some applications, were required.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2000.11b
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• pp.354-362
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• 2000

In Korea, researches on year-round leaf vegetables production system are in progress, most of them focused on environmental control. Therefore, automation technologies for harvesting, transporting, and grading are in great demand. A robot system for harvesting lettuces, composed of a 3-DOF (degree of freedom) manipulator, an end-effector, a lettuce feeding conveyor, an air blower, a machine vision system, six photoelectric sensors, and a fuzzy logic controller, was developed. A fuzzy logic control was applied to determine appropriate grip force on lettuce. Leaf area index and height were used as input variables and voltage as an output variable for the fuzzy logic controller. Success rate of the lettuce harvesting was 94.12%, and average harvesting time was approximately 5 seconds per lettuce.