• Journal of the Korean Society of Food Science and Nutrition
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• v.46 no.10
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• pp.1265-1269
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• 2017

This study was performed to evaluate the effects of combined treatment of clove bud essential oil (CBEO) and mild heat (MH) on inactivation of Escherichia coli O157:H7 inoculated onto red oak leaves. Combined treatment of 0.2% CBEO with MH at $50^{\circ}C$ exhibited the highest inhibitory effect against E. coli O157:H7 among treatments, resulting in 1.45 log reduction compared with water washing treatment. In addition, inhibitory effect of the combined treatment was maintained during storage of red oak leaves at $4^{\circ}C$ for 9 days, showing 1.67~2.25 log reductions compared with non-treated samples. Thus, these results indicate that combined treatment with CBEO/MH can be used to ensure the microbiological safety of fresh leaf vegetables such as red oak leaves during storage.

• 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 Remote Sensing
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• v.33 no.5_1
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• pp.571-585
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• 2017

The number of spaceborne optical sensors including red-edge band has been increasing since red-edge band is known to be effective to enhance the information content on biophysical characteristics of vegetation. Considering that the Agriculture and Forestry Satellite is planning to carry an imaging sensor having red-edge band, we tried to analyze the current status and potential of red-edge band. As a case study, we analyzed the effect of using red-edge band and tried to find the optimum band width and wavelength region of the red-edge band to estimate leaf area index (LAI) of very dense tree canopy. Field spectral measurements were conducted from April to October over two tree species (white oak and pitch pine) having high LAI. Using the spectral measurement data, total 355 red-edge bands reflectance were simulated by varying five band width (10 nm, 20 nm, 30 nm, 40 nm, 50 nm) and 71 central wavelength. Two red-edge based spectral indices(NDRE, CIRE) were derived using the simulated red-edge band and compared with the LAI of two tree species. Both NDRE and CIRE showed higher correlation coefficients with the LAI than NDVI. This would be an alternative to overcome the limitation of the NDVI saturation problem that NDVI has not been effective to estimate LAI over very dense canopy situation. There was no significant difference among five band widths of red-edge band in relation to LAI. The highest correlation coefficients were obtained at the red-edge band of center wavelength near the 720 nm for the white oak and 710 nm for the pitch pine. To select the optimum band width and wavelength region of the red-edge band, further studies are necessary to examine the relationship with other biophysical variables, such as chlorophyll, nitrogen, water content, and biomass.

• The Plant Pathology Journal
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• v.38 no.6
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• pp.551-571
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• 2022

Xylella fastidiosa is xylem-limited bacterium capable of infecting a wide range of host plants, resulting in Pierce's disease in grapevine, citrus variegated chlorosis, olive quick decline syndrome, peach phony disease, plum leaf scald, alfalfa dwarf, margin necrosis and leaf scorch affecting oleander, coffee, almond, pecan, mulberry, red maple, oak, and other types of cultivated and ornamental plants and forest trees. In the European Union, X. fastidiosa is listed as a quarantine organism. Since its first outbreak in the Apulia region of southern Italy in 2013 where it caused devastating disease on Olea europaea (called olive leaf scorch and quick decline), X. fastidiosa continued to spread and successfully established in some European countries (Corsica and PACA in France, Balearic Islands, Madrid and Comunitat Valenciana in Spain, and Porto in Portugal). The most recent data for Europe indicates that X. fastidiosa is present on 174 hosts, 25 of which were newly identified in 2021 (with further five hosts discovered in other parts of the world in the same year). From the six reported subspecies of X. fastidiosa worldwide, four have been recorded in European countries (fastidiosa, multiplex, pauca, and sandyi). Currently confirmed X. fastidiosa vector species are Philaenus spumarius, Neophilaenus campestris, and Philaenus italosignus, whereby only P. spumarius (which has been identified as the key vector in Apulia, Italy) is also present in Americas. X. fastidiosa control is currently based on pathogen-free propagation plant material, eradication, territory demarcation, and vector control, as well as use of resistant plant cultivars and bactericidal treatments.

• Korean Journal of Microbiology
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• v.37 no.1
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• pp.61-65
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• 2001

Epifluorescence microscopy was used to observe epiphytic bacteria directly on plant leaf surfaces as well as indirectly in the leaf liberating solution by staining with fluorochromes of 4',6-diamidino-2-phenylindole (DAPI) and acridine orange(AO). Epiphytic bacteria could not be well observed on the leaf surface by staining with AO due to an intrusive orange or red background fluorescence. However, DAPI gave us clear epifluorescent images of the bacteria on the leaf. On the contrary, epiphytic bacteria in the liberating leaf solution were well observed on filters stained by both types of fluorochrome, although DAPI showed better fluorescent images than AO and not necessarily required a washing step of the filters stained. The optimum conditions of the DAPI stains were 5 $\mu$g/ml for 5 min both for leaves and for filters of the liberating solution. It was confirmed that a critical step in the epifluorescence microscopy of leaf surfaces was to minimize release of water from the leaf. For this, the stained leaf samples were put on a filter paper, kept in a dry oven at $70^{\circ}C$ for 2 min instead of air-drying, and then immediately observed by epifluorescence microscopy. The established technique was applied to enumerate epiphytic bacteria on oak tree leaf surfaces.

• Korean Journal of Food Science and Technology
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• v.20 no.6
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• pp.808-811
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• 1988

Antithiamine activities of dried wild vegetables consumed in Korea were evaluated by means of the thiochrome fluorescence and Lactobacillus viridescens bioassay methods and compared with the phenolic content and the degree of browning of the samples. Eggplant, sweet Potato stalk, bracken, red pepper leaf, Aster scaber and mugwort had higher antithiamine activities than Codonopsis lanceolata, doraji, taro stalk, pumpkin, oak mushroom and acorn starch. Wild vegetables with high antithiamine activity tended to have a high phenolic content and degree of browning. It is recommended that wild vegetables should not be cooked with thiamine-rich foods and be eaten immediately after cooking in order to minimize the thiamine decomposition.

• Journal of Sericultural and Entomological Science
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• v.41 no.1
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• pp.61-69
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• 1999

The dyeing experiments were done by using tannin pigments and herbs for natural fabrics such as ramie, hemp and silk. The anti-bacterial ability and color fastness were examined for dyed fabrics. Dye materials containing tannin pigment such as oak tree leaf showed rich dyeing on ramie, hemp, and silk fabrics when the pH of dye solution is lower as well as the dyeing temperature is higher. In crimson dyeing, the colour of fabric showed red-purple when the crimson pigment was extracted at 40$^{\circ}C$, while yellow-red when extracted above 70$^{\circ}C$. The colour fastness of dye materials containing tannin pigment was excellent showing 3~4 grade or above, while most of those derived from chinese medicine showed poor colour fastness of below 3 grade. The anti-bacterial ability of dye materials derived from chinese medicine was high, since the sappan wood fabric showed low bacteria reduction rate.