• Journal of the Korean Society for Nondestructive Testing
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• v.32 no.5
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• pp.518-525
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• 2012

In this study, the feasibility of hyperspectral reflectance imaging technique was investigated for the discrimination of viable and non-viable lettuce seeds. The spectral data of hyperspectral reflectance images with the spectral range between 750 nm and 1000 nm were used to develop PLS-DA model for the classification of viable and non-viable lettuce seeds. The discrimination accuracy of the calibration set was 81.6% and that of the test set was 81.2%. The image analysis method was developed to construct the discriminant images of non-viable seeds with the developed PLS-DA model. The discrimination accuracy obtained from the resultant image were 91%, which showed the feasibility of hyperspectral reflectance imaging technique for the mass discrimination of non-viable lettuce seeds from viable ones.

• Korean Journal of Plant Tissue Culture
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• v.27 no.1
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• pp.7-12
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• 2000

Explants of lettuce (Lactuca sativa L.) were co-cultivated with Agrobacterium tumifacience GV 3101 strain containing nptII gene and cold regulated gene (BN115) from Brassica napus for transformation. Multiple shoots were obtained from the explants in the selection medium (MS basal medium supplemented with 100 mg/L kanamycin, 500 mg/L carbenicillin, 0.1 mg/L NAA, 0.5 mg/L kinetin) after 3 to 4 weeks of co-culture. The putative transgenic shoots were transferred to rooting medium (1/2 MS basal medium supplemented with 100 mg/L kanamycin and 250 mg/L carbenicillin). The selected shoots were tested with PCR analysis using nptll, BN115 primers whether cold-regulated gene was introduced to genome of the plants. The vir G primers were particularly used to check contamination of Agrobacterium during PCR analysis. The nptII and BN115 primers produced the specific PCR bands in the putative transgenic lines but the vir G primers did not. These results confirmed that the PCR products were not the result of contamination with Agrobacterium. Additionally the Southern analysis of the PCR products and RT-PCR analysis proved that the cold-regulated gene was successfully integrated and transcribed in the putative transgenic lettuce plants.

• Journal of Applied Biological Chemistry
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• v.57 no.2
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• pp.153-157
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• 2014

Plant-growth-promoting rhizobacteria can affect plant growth by various direct and indirect mechanisms. This study was conducted to determine the ability of some rhizobacterial strains to enhance the seed germination of Lactuca sativa (lettuce) and Raphanus sativus (radish). Seeds were inoculated using a spore suspension ($1{\times}10^7cfumL^{-1}$) and incubated in a growth chamber at $28^{\circ}C$ under dark conditions and 65% RH. Azotobacter chroococcum and LAP mix inoculation increased the plumule length of L. sativa by 1.3, 0.8, and 0.7 cm, respectively, in comparison to the uninoculated control. Pseudomonas putida showed an increase of only 0.6 cm in plumule length when compared to the control. Inoculation of A. chroococcum, P. putida, and LAP mix enhanced the seed germination rate of R. sativus, by 10, 5, and 30%, respectively, in comparison with the uninoculated seeds. The results demonstrated that the inoculation of seeds by select rhizobacterial strains showed remarkable enhancement to the radicle length of lettuce and radish seedlings.

• Korean Journal of Plant Tissue Culture
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• v.27 no.6
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• pp.475-478
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• 2000

The cytosolic glutathione reductase(GR) gene of chinese cabbage was introduced into Lettuce (Lactuca sativa L.) with particle bombardment method. When cotyledon explants were treated with osmoticum-conditioning medium (0.6 M sorbitol/mannitol) 4 hours prior to and 16 hours after bombardment, it was identified by GUS assay that this condition was the most efficient one for introduction of foreign genes into cotyledon tissue of lettuce with particle bombardment. The stable integration of a GR gene was confirmed by the PCR analysis. 0.3, 0.6, 1.5 kbp PCR fragments of transgenes were obtained by three types of primers designed on the basis of GR sequence. To know whether the expression of the GR gene of pBKs-GR 1 can be stably maintained in the next generation, T$_2$selfing seeds obtained from the transformed mother plants were sowed on MS medium supplemented with 200 mg/L kanamycin sulfate. 70% of seedlings showed resistance to kanamycin.

• Korean Journal of Microbiology
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• v.13 no.4
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• pp.143-156
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• 1975

A rotting bacterium was isolated from decayed root of ginseng (Panax ginseng Meyer), cultured purely, and its pathogenicity was confirmed by reinoculation test. The strain causing ginseng root rot was identified as Pseudomonas fluoresens biotype II. The strain was somewhat different from P.marginalis and P.talaasii, considering the number of flagella, pathotype and ability of indole production. The strain did not exhibit pathogenicity to other plants tested, such as red kidney bean(Phasolus vulgaris L.), soy bean (Glycine max Merr.), cucumber (Cucumis sativus L.) lettuce (Lactuca sativa L.) and cowpea bean (Vigna sinensis Savi.).

• Horticultural Science & Technology
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• v.29 no.5
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• pp.467-473
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• 2011

Flavonoid are large group of the polyphenolic compounds which are distinguished by an aromatic or phenolic ring structure and the phenolic compounds are induced by microbial infection, ultraviolet radiation, temperature and chemical stress. They are known for their antioxidant activity, anti-allergic, anti-inflammatory, anti-microbial and anti-cancer activities. In this study, changes in flavonoid content were investigated using heterologous chalcone isomerase (CHI) expression system. Also, phenolic compounds level was measured to examine the relation between flavonoids and phenols contents. Explants of lettuce (Lactuca sativa L.) were transformed with Agrobacterium tumefaciens LBA 4404 strain containing pFLH-CHI (derived from pPZP2Ha3) vector constructed with CHI gene from Brassica rapa. The putative transgenic plants were confirmed by genomic DNA PCR analysis. Also the transcription levels of the gene were analyzed by semi-quantitative RT-PCR with gene specific primers. The total flavonoid contents were increased at $T_0$ and $T_1$ generations over 1.4 and 4.0 fold, respectively. Total phenol contents also increased at $T_1$ generation. These results indicate that CHI gene plays an important role to regulate the accumulation of flavonoids and its component changes.

• Journal of the Korean Society of Industry Convergence
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• v.17 no.3
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• pp.145-150
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• 2014

The purpose of this study was to evaluate the growth of lettuce last for 36 days. Lettuce planted on the same medium with different treatment. The first treatment watering using bio-fertilizer (farmer) and second watering using effective microorganism. Lettuce grown in greenhouse with temperature $18-32^{\circ}C$.Characteristic observed that growth in height and weight of the plants. From the observations that can be generated at high observation, treatment 1 had a higher than treatment 2. On the last day treatment plant with treatment 1 had a 99.8 mm high while treatment 2 has height of 90.7 mm. Observation on severe treatment 1 has a heavier weight than treatment 2. Plants with treatment 1 have a weight on the last day of 0.15665 grams while in plants with treatment 2 weights are 0.11365 grams.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.23 no.3
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• pp.163-171
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• 2017

Effects of different packaging methods for maintaining the shelf life and postharvest quality of iceberg lettuce (Lactuca sativa L.) were studied after harvesting in summer season. Lettuce heads were packaged in plastic crate with or without different films such as (A) Individual lettuce head sealed packaging with linear low density polyethylene (LLDPE) film; (B) Packaging lettuce head in plastic crate and wrapped with LLDPE film; (C): Individual lettuce head sealed packaging with perforated high density polyethylene (HDPE) film; (D) Packaging lettuce head in plastic crate and wrapped with perforated HDPE; and (E) Packaging lettuce head in plastic crate without any film (control), and stored at $2^{\circ}C$ for 35 days. Several quality parameters such as fresh weight loss, SPAD (soil & plant analyzer development) meter value, respiration rate, moisture content and appearance of lettuce were investigated. The lettuce wrapped with individually-sealed LLDPE film showed the lowest weight loss and the highest SPAD value rendering the best appearance index among the treataments throughout the three-week storage period at $2^{\circ}C$. Extending the freshness of iceberg lettuce during low temperature storage will definitely increase the salability potential in the domestic market even during summer season.

• Research in Plant Disease
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• v.12 no.3
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• pp.294-297
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• 2006

Leafy lettuce(Lactuca sativa L.) is one of the most important vegetable crops in Korea, cultivated throughout the year in greenhouses. During the autumn of 2005, powdery mildew of lettuce that is a new disease caused by Podosphaera fusca occurred in several plantings grown in plastic houses near Suwon in central Korea. Further survey on commercial fields of the plant in central and southern Korea revealed its widespread occurrence and severe losses. Infections occur on upper part of mature leaves often cause leaf distortions, withering, and reduced vigor and growth. Among 184 greenhouses surveyed 121 were infested by the disease and 52 showed over 10% infection rate. Yields were greatly reduced by the disease reaching only 59% compared to healthy plants. About 60% leaves of infected plant were not marketable and fresh weight of the leaves was 73.6% compared to healthy leaves. Total yield of the greenhouses infested by the disease ranged from $100{\sim}140kg$, while it was 260 kg in a non-infested greenhouse at one time harvest. Since the disease represents a threat to safe cultivation of leafy lettuce in Korea, environmentally-friend control strategies should be urgently developed.

• Korean Journal of Food Science and Technology
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• v.23 no.2
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• pp.133-140
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• 1991

Weight-loss, general-appearante, yellowing, and compositions such as chlorophyll, carotenoid, vitamin C and nitrate, were studied to investigate the influence of pre-(cultivar and growing season) and post-(low-temperature and high-density polyethylene film packaging) harvest factors on the shelf-life and quality of leaf lettuce(Lactuca sativa L). Weight-loss was reduced by the treatment of high-density polyethylene film packaging, and more at $0{\sim}1^{\circ}C$ than $4{\sim}5^{\circ}C$. Leaf-lettuce grown in Winter lost less fresh weight than that grown in Autumn. In experiment on difference between cultivars, the reduction of weight-loss in 'Cheongchima' lettuce was somewhat significant than that in 'Jeokchukmyeon' lettuce. The tendency of changes in general appearance was similar to that of weight-loss. The yellowing of leaf lettuce during the storage was caused by chlorophyll degradation. Vitamin C content before the storage was 128.0 mg/100 g FW. in lettuce grown in Winter, 123.8 mg/100g FW. in that grown in Autumn, and more 'Cheongchima' lettuce than 'Jeokchukmyeon' lettuce. In all treatment, vitamin C content decreased rapidly, and this tendency was more obvious at $4{\sim}5^{\circ}C$ than $0{\sim}1^{\circ}C$. The nitrate content of 'Jeokchukmyeon' was 3812.6 ppm and that of 'Cheongchima' was 2855.6 ppm before the storage. Nitrate content decreased more at $4{\sim}5^{\circ}C$ than $0{\sim}1^{\circ}C$ during the storage.