• Journal of Environmental Science International
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• v.31 no.5
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• pp.405-411
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• 2022

Production of lettuce under indoor cultivation is highly affected by light intensity. In this study, we used shade cloth (commercial black net) to examine the effect of these condition on growth without an associated yield penalty of container-grown lettuce. Four levels of shading treatments (0%, 35%, 55%, and 75% referred to as Cont., S₃₅, S₅₅, and S₇₅ with respect to Cont.) and two lettuce varieties (red and blue) were evaluated. Variety-specific growth responses were observed with respect to different levels of shading treatments. High growth of red lettuce was occurred in Cont. treatment despite plant height and leaf length being higher than Cont. However, under 35% shading treatment blue lettuce was higher than in control plants. The highest root length was observed 0% shading (Cont.) of both varieties. These results reinforce the idea that blue lettuce is the better leafy vegetable rather than red lettuce for indoor cultivation related to lower light intensity environment conditions.

• The Korean Journal of Food And Nutrition
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• v.37 no.2
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• pp.88-99
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• 2024

This study aimed to provide an accurate estimate of sodium intake from jangajji by examining the changes in sodium content according to the type of jangajji and the length of storage period, specifically differentiating between the solid ingredients and the seasoning liquid. It focused on six types of jangajji: chili pepper, perilla leaf, onion, radish, garlic scape, and cucumber. The sodium content in the solid ingredients and the seasoning was measured using a salinometer and ICP-AES. The results indicated that across all types of jangajji, the seasoning liquid consistently contained significantly higher levels of sodium than the solid ingredients. When comparing the sodium content measured by ICP-AES with that from a salinometer, the salinometer readings were significantly lower for both the solid ingredients and the seasoning liquid in all types of jangajji. Additionally, when comparing the sodium content of the solid ingredients with that listed in the nation's representative nutritional databases, a substantial discrepancy was noted, with some cases potentially overstating the actual sodium intake from jangajji. Overall, this study suggests that an urgent review should be conducted to identify and resolve the causes of such discrepancies and accurately estimate the actual sodium intake from jangajji.

• Journal of Microbiology and Biotechnology
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• v.34 no.7
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• pp.1395-1400
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• 2024

The antimicrobial activity of the natural compounds from plant and food have well discovered since the interest on the beneficial effect of the natural compounds was risen. Quercetin, a flavonoid derived from vegetables, including onions, red leaf lettuces and cherries has been studied for diverse biological characteristics as anti-cancer and anti-microbial activities. The aim of current study is to investigate the specific antibacterial modes of action of quercetin against Escherichia coli. Quercetin decreased the E. coli cell viability and induced the severe damages (oxidative stress, DNA fragmentation) leading to cell death. Reactive oxygen species (ROS) generation was observed during the process, which we confirmed that oxidative stress was the key action of antibacterial activity of quercetin exerting its influence potently. Based on the results of Annexin V and Caspace FITC-VAD-FMK assay, the oxidative damage in E. coli has led to the bacterial apoptosis-like death in E. coli. To sum up, the contribution of ROS generation exerts crucial impact in antibacterial activity of quercetin.

• Korean Journal of Food Science and Technology
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• v.43 no.2
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• pp.161-168
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• 2011

The purpose of this study was to evaluate microbiological contamination of fresh vegetables in Korea. Twenty types of vegetables were tested for total aerobic bacteria, coliforms, Escherichia coli, yeast and mold, and pathogenic bacteria such as Staphylococcus aureus, Listeria monocytogenes, Bacillus cereus, Salmonella, E. coli O157:H7, Cronobacter sakazakii, Shigella, and Campylobacter. Levels of total aerobic bacteria and coliform on 20 vegetables were between 3.74 and 8.04 log CFU/g, and 0.16 and 5.02 log CFU/g, respectively. The highest contamination levels of total aerobic bacteria were observed on water dropwort, sprouts, mungbean sprout, and ballflower root. There was no significant difference (p>0.05) in microbial contamination levels of total aerobic count, coliform, E. coli, yeast and mold between organic and nonorganic vegetables. When isolation methods using selective agars were applied, L. monocytogenes, B. cereus, Salmonella and Campylobacter were isolated from some fresh vegetable samples. Results of API kit tests showed that L. monocytogenes was identified on Chinese cabbage, cucumber, soybean sprouts, and iceberg lettuce while Salmonella was identified on Korean leek. Furthermore, Campylobacter jejuni was also identified in more than 50 of the 100 samples. However, when positive samples from API kit were tested for real-time PCR or 16S rRNA sequencing method, only B. cereus from perilla leaf, carrot, water dropwort, and sprouts showed positive results. These results indicate that selective agar and API kit detection methods might result in false positive results for some pathogens. Therefore, studies need to improve isolation or confirmation methods for such pathogens.

• Journal of Bio-Environment Control
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• v.30 no.4
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• pp.401-409
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• 2021

This study aimed to estimate the photosynthetic capacity of tomato plants grown in a semi-closed greenhouse using temperature response models of plant photosynthesis by calculating the ribulose 1,5-bisphosphate carboxylase/oxygenase maximum carboxylation rate (V_cmax), maximum electron transport rate (J_max), thermal breakdown (high-temperature inhibition), and leaf respiration to predict the optimal conditions of the CO₂-controlled greenhouse, for maximizing the photosynthetic rate. Gas exchange measurements for the A-C_i curve response to CO₂ level with different light intensities {PAR (Photosynthetically Active Radiation) 200µmol·m^-2·s^-1 to 1500µmol·m^-2·s^-1} and leaf temperatures (20℃ to 35℃) were conducted with a portable infrared gas analyzer system. Arrhenius function, net CO₂ assimilation (A_n), thermal breakdown, and daylight leaf respiration (R_d) were also calculated using the modeling equation. Estimated J_max, A_n, Arrhenius function value, and thermal breakdown decreased in response to increased leaf temperature (> 30℃), and the optimum leaf temperature for the estimated J_max was 30℃. The CO₂ saturation point of the fifth leaf from the apical region was reached at 600ppm for 200 and 400µmol·m^-2·s^-1 of PAR, at 800ppm for 600 and 800µmol·m^-2·s^-1 of PAR, at 1000ppm for 1000µmol of PAR, and at 1500ppm for 1200 and 1500µmol·m^-2·s^-1 of PAR levels. The results suggest that the optimal conditions of CO₂ concentration can be determined, using the photosynthetic model equation, to improve the photosynthetic rates of fruit vegetables grown in greenhouses.

• Research in Plant Disease
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• v.26 no.4
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• pp.272-278
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• 2020

The severe lettuce damage caused by Paratylenchus projectus was first reported in 2019 in Korea. To find high-value rotation crops for the control of P. projectus, nine vegetables, Brassica juncea (leaf mustard), B. rapa subsp. nipposinica (kyona), B. oleracea var. italica (broccoli), B. rapa subsp. chinensis (bok choy), B. oleracea var. viridis (kale), B. oleracea var. gongylodes (kohlrabi), Cichorium endivia (endive), C. intybus (chicory), Ipomoea aquatica (morning glory) were planted in d-10-cm clay pots in greenhouse. The growth of vegetables was compared between inoculated with 3,000 P. projectus per 100 ㎤ of soil and non-inoculated. Treatments were replicated 10 times. After 100 days, the reduction of fresh top weight was 30.4% in C. intybus, 35.1% in I. aquatica, 36.9% in B. oleracea var. acephala, 40.5% in C. endivia, 42.1% in B. rapa, 47.5% in B. rapa subsp. nipposinica, 50.4% in B. oleracea var. gonglodes, 56.3% in B. oleracea var. italica, and 66.0% in B. juncea. Nematode multiplication rates (Pf/Pi) were lower in I. aquatica (0.64) and C. endivia (1.1), but higher in B. oleracea var. gongylodes (2.54). Considering these results, I. aquatica is suitable for the rotation crop with lettuce until better rotation crops developed.

• The Korean Journal of Pesticide Science
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• v.19 no.4
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• pp.399-401
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• 2015

This study investigated the plant growth promoting activity of geraniol on Chinese cabbage (Brasscia campestris ssp. Pekinensis Rupr.), Pak Choi (Brassica rapa L.), Crown daisy (Chrysanthemum coronarium L.), Iceberg lettuce (Lactuca sativa L.) and Leaf perilla (Perilla frutescens Britt.). Geraniol at 0.5 to $10mg\;L^{-1}$ promoted radical growth of Chinese cabbage Pak Choi, Crown daisy, Iceberg lettuce and leaf perilla by >30%. In the pot experiments, geraniol treatment at $20mg\;L^{-1}$ by drenching increased up to 190% of the aerial part growth promotion. By comparison, foliar application showed 124% promoting activity only at $100mg\;L^{-1}$.

• Korean Journal of Food Science and Technology
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• v.38 no.4
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• pp.594-598
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• 2006

The aim of this study was to investigate the prevalence and frequency of food-borne pathogens in unprocessed Products such as grains, tubers, vegetables, and seaweeds. Three hundred and twenty seven samples were purchased from the retail market and the supermarket in the Kyonggi-do and Seoul areas, and washed with running tap water for 4 minutes. The total aerobic bacteria count was approximately 2 to 6 log CFU/g and the highest counts were 6 log CFU/g far lettuce and sesame leaf. The coliform count showed 1-5 log CFU/g and the highest counts were 4 log CFU/g for lettuce and carrot. Escherichia coli was detected in seven samples of white rice, sweet potato, lettuce, sesame leaf, and cabbage. Clostridium perfringens was detected in six samples of brown seaweed, laver, lettuce, and sweet potato. However, Bacillus cereus contamination was found in more than 30% of brown rice, carrot, sweet potato, lettuce and sesame leaf samples, and some of these showed contamination of more than 2.0 log CFU/g. Therefore, these results suggest that pretreatment with sanitizer to remove Bacillus cereus in such products is necessary.

• The Korean Journal of Pesticide Science
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• v.10 no.3
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• pp.183-188
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• 2006

A nation-wide monitoring survey was performed to look into pesticide use pattern and amount on farmers' field after the national registration of pesticides from 2003 to 2004. Tow hundred ninety two leading farmers involved in the survey were chosen from main cultivating regions of targeted crops in consideration with area. Most farmers involved in the survey follow the safe use guideline of pesticides, while their information to select and making-decision for purchasing pesticides were done according to the recommendation of mainly pesticide market dealers or agricultural cooperative dealers. Used amount of pesticide per unit cropping area was surveyed as 5.51 on paddy, 3.91 on field cabbage, 2.93 on greenhouse cabbage, 0.76 on lettuce, 0.55 on spinach, 1.34 on perilla leaf, 4.89 on leek and 0.42 kg $ha^{-1}$ on young radish. As compound with those surveyed from 1999 to 2000, the pesticide amounts used for rice, lettuce and perilla leaf were reduced while that for cabbage was increased.

• Journal of Bio-Environment Control
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• v.18 no.2
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• pp.119-123
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• 2009

Waste nutrient solution (WNS) that composed of nutrient solution of horticultural research institute in Japan and used for culture tomato in perlite hydroponics showed $1.9{\sim}2.4$ dS/m of EC and $5.5{\sim}7.1$ of pH. Although $NH_{4}^+$-N concentration of WNS decreased remarkably, the others did not change significantly as compared with supplied solution. The growth characteristics such as plant height, stem diameter, leaf length, and leaf width were increased as amount of compost was increased in 1 L WNS supply treatment. But there was not any regular tendency on growth characteristics in 2 L/plant WNS supply treatment. The chlorophyll content of tomato leaf was highest in I L/plant WNS supply and 4,000 kg/10a compost treatment. The fresh and dry weight, and yield of tomato fruit also increased with increase of amount of WNS and compost, and they were highest in 1 L WNS supply and 4,000 kg/10a compost treatment. The sugar content of tomato fruits was not influenced by amount of WNS and compost, fructose and glucose and total sugar was highest in 2 L/plant WNS supply and 2,000 kg/10a compost treatment. Therefore fertigation culture used WNS is environmentally friendly and can guarantee yield and quality of tomato fruits and growth of tomato plants.