• Journal of Bio-Environment Control
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• v.8 no.2
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• pp.108-114
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• 1999

This study was conducted to investigate the optimum environment for leaf lettuce (Lactuca sativa L. var. crispa) in a plant factory to increase mass-production efficiency of quality leaf lettuce. Transpiration rate and $CO_2$ assimilation rate were increased with increasing the photosynthetic photon flux density (PPFD). The highest fresh weight and dry weight were observed at the PPFD of 200 and 300 U moi $m^{-2}$ $s^{-l}$, respectively. The optimum aerial environment for the growth and quality of leaf lettuce in the plant factory was determined to be over 200 $\mu$mol $m^{-2}$ $s^{-1}$ for PPFB. Although the interaction between light intensity and nutrient level was not significant, the lettuce growth was the best under electrical conductivity (EC) of 1.8 mS $cm^{-1}$ / at high light intensity (250 $\mu$mol $m^{-2}$ $s^{-1}$ ) and EC of 2.4 mS cm-1 at low light level (150 $\mu$mol $m^{-2}$ $s^{-1}$ ) respectively.y.

• Journal of Environmental Science International
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• v.24 no.8
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• pp.1075-1084
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• 2015

This study was conducted to investigated the changes in the nutrient 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) on the leaf lettuce (Lactuca sativa L.) grown with hydroponics. Recirculating hydroponic cultivation system was consisted of planting port, LED lamp, water tank, and circulating pump for hydroponic. Nutrient solution was used in the standard solution for Japan vegetables experimental station and commercial hydroponic. The result showed that electrical conductivity (EC), total dissolved solids (TDS) and pH, depending on the growth of lettuce decreased continuously. With the growth of the lettuce, nitrate nitrogen, ammonia nitrogen, phosphate phosphorus were required for periodic replacement. The number of pH compensation due to the growth of lettuce are the most high. The concentration of $Ca^{2+}$ and $Mg^{2+}$ during the lettuce growth showed no significant change. However, $K^+$ concentration increased due to the replacement with nitrogen and phosphorus. Electric conductivity and total dissolved solids with total nutrient concentration showed the linear relationship and the correlation coefficient $R^2$ were 0.8601 and the 0.827, respectively.

• Journal of Life Science
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• v.17 no.6 s.86
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• pp.822-824
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• 2007

The efficient system for plant regeneration from cotyledon and primary feat explants of lettuce was established. Plant regeneration efficiency was shown 91.3% from cotyledon and 85.9% from primary leaf explants of variety 'Jungtongpogi' in KN medium. Plant regeneration efficiency was also estimated with various plant regeneration media in variety' Chungchima', which was lowest plant regeneration efficient showing 35.4% from cotyledon and 30.3% from prima leaf explants in KN medium. Kl medium increased 77.9% and 80.7% of plant regeneration efficiencies from cotyledon and primary leaf explants of variety 'Jungtongpogi' were cultured on KN medium. In case of varie쇼 ‘Chungchima', efficient plant regeneration was shown when primary leaf explants were cultured on SH and KI media.

• 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.

• Horticultural Science & Technology
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• v.34 no.4
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• pp.596-606
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• 2016

The growth and contents of anthocyanins and ascorbic acid in lettuce(Lactuca sativa L., 'Jeokchima') as affected by supplemental UV-A LED irradiation under different light quality and photoperiod conditions were analyzed in this study. Five light qualities, namely B (blue LED), R (red LED), BUV (blue LED+UV-A LED), RUV (red LED+UV-A LED) and Control (white fluorescent lamps) with photoperiods of 12/12 hours (day/night), 16/8 hours, or 20/4 hours were provided to investigate the effects of light quality and photoperiod on the growth and accumulation of anthocyanins and ascorbic acid in lettuce leaves. As measured 28 days after transplanting, the number of leaves, leaf length, leaf width, leaf area, shoot fresh weight and dry weight of lettuce were significantly affected by light quality and photoperiod. The number of leaves, leaf length, leaf width, leaf area, shoot fresh weight and dry weight of lettuce grown under R treatment increased with increasing light period. By contrast, leaf development was inhibited, but chlorophyll content increased, under B treatment. Supplemental UV-A irradiation significantly decreased leaf length, leaf width, leaf area and shoot fresh weight. Anthocyanins in lettuce increased significantly with decreasing dark period under B treatment. A synergistic effect of supplemental UV-A LED irradiation on anthocyanins accumulation was found for lettuce leaves grown under R treatment but not B treatment. Ascorbic acid in lettuce was greatly affected by photoperiod. Ascorbic acid content at BUV and RUV treatments increased by 20-30% compared to without UV-A LED irradiation. From these results, it was concluded that growth and contents of anthocyanins and ascorbic acid in lettuce are significantly affected by supplemental UV-A LED irradiation. The results obtained in this study will be informative for efforts to improve the nutritional value of leafy vegetables grown in plant factories.

• 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 Practical Agriculture & Fisheries Research
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• v.22 no.1
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• pp.55-63
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• 2020

This study aimed to investigate responses of plant growth and photosynthesis to different kinds of covering materials with selective light transmit for red leaf lettuce (Lactuca sativa L.). Experimental pot design was attached UV blocking filter, red filter, blue filter, and green filter. The kinds of covering materials showed significant results for plant growth especially control, UV blocking filter, and red filter. The photosynthetic rate and anthocyanin content of red leaf lettuce were higher in control and UV blocking filter than others. The quality of red leaf lettuce was low in red, green, and blue film treatments because of too low anthocyanin content.

• Journal of Bio-Environment Control
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• v.22 no.4
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• pp.400-407
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• 2013

This study was performed to analyze the effect of light quality of discharge lamp on growth and phytochemicals contents of lettuce (Lactuca sativa L. cv. Jeokchima) grown under metal halide (MH) lamp, high-pressure sodium (HPS) lamp, and xenon (XE) lamp in a plant factory. Cool-white fluorescent (FL) lamp was used as the control. Photoperiod, air temperature, relative humidity, $CO_2$ concentration, and photosynthetic photon flux (PPF) in a plant factory were 16/8 h (day/night), $22/18^{\circ}C$, 70%, 400 ${\mu}mol{\cdot}mol^{-1}$, and 200 ${\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$, respectively. MH lamp had the greatest fraction of blue light (400-500 nm) of 23.0%. However, HPS lamp had the lowest fraction of 4.7% for blue light and the greatest fraction of 38.0% for red light (600-700 nm). At 11 and 21 days after transplanting, leaf length, leaf width, leaf area, shoot fresh weight, and shoot dry weight of lettuce as affected by the light quality of the discharge lamp were significantly different. The leaf area of lettuce grown under HPS, MH, and XE lamp increased by 45.7%, 16.3%, and 9.5%, respectively, as compared to the control. These results were similar for shoot fresh weight. Growth characteristics of lettuce grown under HPS lamp increased since HPS lamp had more fraction of red light. However, growth of lettuce grown under MH and XE lamp decreased since they had more fraction of blue light. As compared to the control, the ascorbic acid in lettuce leaves grown under discharge lamp decreased. The greatest anthocyanins accumulation of 0.70 mg/100 g was found at MH treatment. Anthocyanins content in lettuce leaves grown under XL and HPS lamp were 79.3% and 8.6%, respectively, compared with the control. Growth and phytochemicals contents of lettuce were highly affected by the different spectral distribution of the discharge lamp. These results indicate that the combination of discharge lamp or LED lamp for enhancing the light quality of discharge lamps is required to increase the growth and phytochemicals accumulation of lettuce in controlled environment such as plant factory.

• Journal of Distribution Science
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• v.16 no.8
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• pp.63-68
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• 2018

Purpose - Lettuce (Lactuca sativ L.) is one of the economically important vegetable crops, which worldwide market value is over 100 billion U.S. dollar. In Korea, about 89.7 kilo ton of lettuce was produced in 3400ha in 2016, recoded as No. 1 vegetable crop in domestic green house production. However, recently, domestic lettuce production and cultivation areas are all getting decreased. Thus, novel approaches are needed to be implemented to revive the production. Research design, data and methodology - In this review paper, we first prioritized the end-user traits which are imperative to positively stimulate the domestic lettuce market and discussed relevant genomics strategies. Especially, we assessed a possibility whether school meal program would be a potential niche market. Results - The genomics technologies, which become widely applied in the crop biotechnology since 2008 when next generation sequencing method was developed, may be a good solution in the crop improvement, efficiently gathering valuable information of agriculturally useful traits. Significantly, in lettuce, the high quality whole genome sequence, based on Lactuca sativa cv. Salinas, is publically available and this genomics platform, thus, would be implemented in lettuce breeding program to innovate relevant end-user traits both for the farmers and customers, including the disease resistance to the Fusarium wilt, productivity under hot weather conditions, various nutritional qualities and so forth. These improvements will boost domestic lettuce industries in the near future. Conclusions - Due to the nutritional distinctions comparing to the western style lettuces, domestic leaf lettuces could be one of the important vegetables in the school meal programs. To make it happen, we would better devise diverse recipes to make a salad with it, instead of only using as a wrap vegetable. Meanwhile, novel lettuce varieties need to be developed, which are favorable to the students and also easy to be handled with while processing. Overall, to achieve international competence in the lettuce industries, we need to create elite lettuce varieties that satisfies domestic farmers as well as customers, suitable to various niche markets, such as school meal program. Thus, efficient breeding programs using genomics approaches should be established in advance and careful monitoring on the preference of the related customers for a niche market be continued persistently.

• Journal of Bio-Environment Control
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• v.7 no.1
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• pp.35-41
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• 1998

This experiment was conducted to find out the effect of artificial light sources(high-pressure sodium lamp, metal halide lamp and fluorescent lamp) on growth of crisphead lettuce(Lactuca sativa L.) in a plant factory. No significant differences in leaf fresh and dry weight were presented among them. Lettuce plants grown under fluorescent lamp showed the lowest growth. Considering the growth of lettuce and efficiency of lamps, it is worth using HPS(high-pressure sodium) lamp in plant factories. The leaves of lettuce plants grown under artificial light sources showed tipburn symptoms at 14th day after transplanting. The beginning of tipburn symptom have been seen on the ninth to tenth leaves from the cotyledons. It is estimated that the occurrence of tipburn was related to rapid growth and K uptake of the lettuce Plants. The Ca, Mg. Cu and Zn elements tended to be accumulated in the nutrient solutions but the T-N, P, Fe and Mn elements keep in balance in them.