• Horticultural Science & Technology
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• v.33 no.6
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• pp.883-890
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• 2015

The soilborne fungus Fusarium oxysporum f. sp. lilii (Fol) is a serious threat to all lily cultivars, especially infecting bulbs and flowers. It has become increasingly important to develop varieties resistant against the bulb rot disease. Genetic diversity of cultivars and reliable screening methods are required for this purpose. Here, an efficient in vitro screening system for evaluating resistance to Fol in 38 in vitro-grown lily plants was investigated. Various factors including culture conditions of Fol, inoculum density, appropriate plant materials, inoculation method and duration, and incubation period of plant materials after inoculation were combined to optimize the screening method. As a result, we suggest optimal conditions for an in vitro screening system for the selection of Fol-resistant lily cultivars as follows. Fol was grown on potato dextrose agar (PDA) medium for 6 days at $25^{\circ}C$ in darkness and used as working inoculation. Spore suspensions were prepared (inoculum density: $1.0{\times}10^4$ $spores{\cdot}mL^{-1}$), and then leaf segments $1.5{\times}2.0cm^2$ were inoculated by dipping for 22 hours at $25^{\circ}C$ in dark. Later, leaves were cultured on 0.6% agar plates at $25^{\circ}C$ and 50% humidity with a photoperiod of 16 hours light/8 hours dark (fluence rate of $40{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$) to examine the progress of bulb rot. After 7 days, disease levels were classified into indices 1 (no symptom) to 6 (serious bulb rot). Soil inoculation of Fol carried out with resistant or susceptible lily cultivars that had been selected through in vitro screening confirmed the reproducibility of results. Therefore, the in vitro screening method established in this study is efficient and reliable for selection of lily cultivars resistant against bulb rot disease.

• Journal of Korean Society of Forest Science
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• v.103 no.3
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• pp.359-367
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• 2014

This study was carried out to determine the effects of seed storage methods and pre-treatments on seed germination, soil types and shading conditions on potted seedlings growth of S. sieboldiana var. pendula and S. sieboldiana for. xanthocarpa, endemic species in Korea. The seed germination rate of S. sieboldiana var. pendula was the highest at 48.6% when seeds were treated with stratification for 60 days and then soaked in 100 ppm $GA_3$. And seed germination rate of S. sieboldiana for. xanthocarpa was the highest at 51.4% when seeds were pre-chilled for 30 days and then soaked in 100 ppm $GA_3$. And potted seedlings of S. sieboldiana var. pendula showed the best quality under 50% shading in bedsoil with the growth characteristics of plant height (41 cm), number of leaves(8), leaf width (16 cm), leaf length (18 cm), root length (22 cm), fresh weight(aerial part/root part; 20/6.9 g) and dry weight(aerial part/root part; 4.5/2.0 g). And potted seedlings of S. sieboldiana for. xanthocarpa showed the best quality under non-shading in bedsoil with the growth characteristics of plant height (39 cm), number of leaves(10), leaf width (12 cm), leaf length (15 cm), root length (22 cm), fresh weight (aerial part/root part; 21/13 g) and dry weight (aerial part/root part; 4.2/2.2 g). Therefore, seeds treated with stratification or prechilling and then soaked in $GA_3$ were effective in germination of S. sieboldiana var. pendula and S. sieboldiana for. xanthocarpa, and potted seedlings should be cultivated in bedsoil under non or 50% shading condition.

• Korean Journal of Environmental Agriculture
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• v.14 no.3
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• pp.302-311
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• 1995

Benfuresate or oxolinic acid, as an experimental pesticide, was applied to the different textural paddy or upland soil respectively under the field condition and the residual concentrations were determined. Six kinetic models were employed to characterize the best-fit kinetic model describing the residual pattern of benfuresate or oxolinic acid and the $t\frac{1}{2}$ estimated from each model was comparatively assessed. All of the six models explained significantly the residual patterns of the pesticides but the empirical models such as PF, EL, and PB were not recommendable for the $t\frac{1}{2}$ estimation. Among theoretical models, the residual patterns were followed in the orders of the second-order(SO)>first-order(FO)>zero-order(ZO) kinetics, judging from the size and significance of coefficient of determination and standard error. However, the multiple FO model, consisting of the fast and slow decomposition steps, was better than the single FO model for the residual pattern and the $r^2$ in this case became similar to that of SO kinetic model. Thus the multiple FO and SO models were represented as the best fit model of the experimental pesticide. The $t\frac{1}{2}$ of benfuresate estimated from the single FO kinetic model in Weolgog and Cheongwon series was 49 and 63 days, respectively, which were 20 and 13% longer than the respective $t\frac{1}{2}$ from the SO kinetic model. The $t\frac{1}{2}$ of oxolinic acid from the FO model in Yonggye and Ihyeon series were 87 and 51% longer than those from the SO kinetic model, respectively. These results demonstrated that the best-fit model representing the residual pattern of a pesticide and the resultant $t\frac{1}{2}$ might be variable with the kinds of pesticides and the environmental conditions. Therefore it is recommended that the half-life of a pesticide be assessed from the best-fit model rather than from the FO kinetic model uniformly.

• Journal of the Korean earth science society
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• v.34 no.6
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• pp.515-523
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• 2013

The eastern coast of South Korea is expected to be damaged by volcanic ash when Mt. Baekdusan volcano erupts. Even if the amount of volcanic ash is small, it can be fatal on the agricultural sector withering many plants and causing soil acidification. Thus, in this paper, we aim to estimate agricultural losses caused by the volcanic ash and to visualize them with Google map. To estimate the volcanic ash losses, a damage assessment model is needed. As the volcanic ash hazard depends on the kind of a crops and the ash thickness, the fragility function of damage assessment model should represent the relation between ash thickness and damage rate of crops. Thus, we model the fragility function using the damage rate for each crop of RiskScape. The volcanic ash losses can be calculated with the agricultural output and the price of each crop using the fragility function. This paper also represents the estimated result of the losses in Gangwon province, which is most likely to get damaged by volcanic ashes in Korea. According to the result with gross agricultural output of Gangwon province in 2010, the amount of volcanic ash losses runs nearly 635,124 million wons in Korean currency if volcanic ash is accumulated over four millimeters. This amount represents about 50% of the gross agricultural output of Gangwon province. We consider the damage only for the crops in this paper. However, a volcanic ash fall has the potential to damage the assets for a farm, including the soil fertility and installations. Thus, to estimate the total amount of volcanic ash damage for the whole agricultural sectors, these collateral damages should also be considered.

• Korean Journal of Soil Science and Fertilizer
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• v.38 no.1
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• pp.1-7
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• 2005

The levels of polyamines were measured to investigate the alternative nitrogen metabolism during maturation and sprouting in rice. The rice plants (cv. Ansanbyeo) were cultivated in 20-year-old non-fertilized field. The flag leaves and spikes were collected weekly after the earing stage and the seeds were harvested daily after lodging. Free, bound, and conjugated polyamines were analyzed using reverse phase HPLC. Putrescine, spermidine, spermine, agmatine and tyramine were the major amines found in rice. The level of stress-induced amine, putrescine increased during the preharvest sprouting confirming that the process was a stress to the plants. With all other polyamines, tyramine in free form decreased in flag leaves and panicles during seed maturation. However, agmatine in bound form showed a noticeable increase about 8-fold during 6 weeks period of maturation after which it declined to the bottom level. Among the individual amines, tyramine and spermine in conjugated form showed a marked change during matutation and sprouting. Interestingly, the level of tyramine with all conjugated polyamine decreased in spikes during seed maturation and increased during preharvest sprouting implying that tyrosine decarboxyation and conjugation to phenolic acids may play a key role in preharvest sprouting. Spermine in conjugated form was synthesized only at the early earing stage in the level of $3.4mole\;g^{-1}$ fresh weight, and then decreased to the level of nmole during maturation. Thereafter, it dramatically increased to 2.8 mole during preharvest sprouting. In this study we found the tyramine is a major amine in rice, and it would play a critical role in N-assimilation during seed maturation and sprouting.

• The Korean Journal of Pesticide Science
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• v.18 no.2
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• pp.88-94
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• 2014

Among pre-harvest environmental factors, increasing attention has been paid to the effects of chemical and microbiological factors on fresh produce. The occurrence and prevalence of these factors have been usually studied with regard to the final products at the post-harvesting stage and/or when they are sold in the market. However, the origin and routes of transmission of both factors remain to be clarified. In the present study, we examined the contamination levels of food-borne pathogens and chemical factors such as pesticide residues and heavy metals in 83 and 43 samples, respectively, including various soil, water, and fertilizer samples, as well as post-harvested and processed samples. Among the organic farming samples, only one pesticide, dimethomorph, was detected in the soil sample, however no pesticides were observed from any other samples in organic farming system. Thus, it was thought that might be contaminated from conventional farm land in the vicinity. Whereas many pesticide residues were detected in conventional farming systems such as soil, fertilizer, water, and fresh produce as expected. Furthermore, heavy metals detected from all tested samples did not shown contamination levels higher than the standard limit. We comparatively assessed the levels of contamination by food-borne pathogens on the samples from organic and conventional farming systems, and found aerobic bacteria at approximately 7 log CFU/g, with no significant differences observed between the two systems. Coliforms were present at lower levels than aerobic bacteria. No human pathogens were present among the coliforms detected, indicating that these bacteria are saprophytes without the ability to cause food-borne illnesses. In contrast, among the high-risk food-borne pathogens, only sporadic cells of Bacillus cereus were found on samples of organic farming system. These data extend previous findings that the most prevalent food-borne pathogen is B. cereus and demonstrate that it spreads to whole living plants via soil.

• Korean Journal of Plant Taxonomy
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• v.41 no.1
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• pp.66-80
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• 2011

This study investigated the environmental factors and conducted a RAPD analysis for a better understanding of the environmental characteristics and regional genetic variation in samples from 18 different areas of Viola diamantiaca. The habitats are mostly located on the slopes of mountains facing north at an altitude ranging from 614 m to 1,462 m above sea level with angles of inclination ranging from 3 degrees to 30 degrees. A total of 268 vascular plant taxa are identified in 35 quadrates of 18 habitats. The importance value of V. diamantiaca is 11.58%, and four highly ranked species, Sasa borealis (5.61%), Meehania urticifolia (5.21%), Ainsliaea acerifolia (3.62%), Pseudostellaria palibiniana (3.60%) are considered to have an affinity with V. diamantiaca in their habitats. The degree of their average species diversity is 1.36, while this metric for their evenness and dominance are 0.89 and 0.07, respectively. The average field capacity of the soil is 25.99%, with organic matter at 17.47%, and the pH is 5.19. The soil texture was confirmed as sandy loam of eleven and loam of seven. The result of the RAPD analysis, among 78 bands amplified with a primer, 64 (84.6%) showed polymorphism. Eighteen populations could be classified into five groups with similarity coefficient values ranging from 0.53 to 0.86. The Mt. Jiri population, which is geographically segregated, shows basal branching within the 18 populations. Five populations, including two in the southern district in Gangwon-do and three in Chungcheongbuk-do, form a distinct clade. Four populations in the central district of Gangwon-do and Mt. Bohyeon in the Gyeongsangbuk-do clade form a sister to the clade containing two populations in Gyeonggi-do and five populations of the northern district in Gangwon-do. The Mt. Gariwang population is placed between the southern district and the central district in the Gangwon-do clades.

• Korean Journal of Soil Science and Fertilizer
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• v.26 no.1
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• pp.37-42
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• 1993

Influences of metal concentration, pH and temperature on metal-ligand precipitate formation were investigated, as a part of projects for removing heavy metals from aqueous solution employing the principles in metal-ligand complexation. Aqueous solutions of HA or FA were reacted with those of heavy metals with 1:1 ratio. Efficiency of humic (HA) or fulvic acid (FA) on removing metals was evaluated by separating the precipitates from soltuions with the filtering method. When HA was a counter ligand, there existed three ranges of metal concentrations affecting precipitation : precipitate fromation was not available, was reached to the maximum, and afterwards was decreased again. The concentration ratios of metal to HA for initiating complexation were dependent upon kinds of metal and concentrations of ligand. Amount of Pb to form maximum precipitates per unit mg of HA was 1.3 times higher than that of Cu. When FA was a counter ligand, concentrations of metal-FA precipitates were increased proportionally with the treated metal concentrations. Efficiency of FA fro removing Pb was nearly 100%, but it was ranged from 12 to 19% for Cu, depending on FA concentration. pH exerted a considerable effect on complexation between Pb and FA, showing precipitates were increased six times at most per unit increase of pH. Ranges of pH increasing significantly the mounts of precipitates were coincied with pH jump ranges of the titration curve of organic ligands. As increasing temperature from 15 to $55^{\circ}C$, increases of FA-Cu precipitates were doubled, but those of FA-Pb were accounted for only 6%, However, HA-metal complexation was not affected by temperature.

• Korean Journal of Environment and Ecology
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• v.24 no.3
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• pp.249-257
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• 2010

The purpose of this paper is to weigh the possibility of endangered Jang-hang wetland at the estuary of Han River to be included on the Ramsar List of Wetlands of International Importance and come up with ways to manage the wetland depending on its biotope patterns. The target area is located between Gimpo bridge and Isanpo I.C. with about $2.7km^2$ area. Through the analysis of RIS(Information Sheet for Ramsar Wetlands), it was known that the wetland is located on the sedimentary topography and formed as a result of sediment at the estuary of the river owing to the concentration of rainfall during summer. The vegetation environment in the area is divided into brackish water and fresh water areas depending on salinity. Rhizosphere soil(RS) of the area was analyzed to be Silt loam while bottom RS to be Sand loam. The plant ecology was composed of 52 families 135 species and 11 varieties and 146 types. Among indigenous species found are Salix koreensis, Phragmites communis and Miscanthus sacchariflorus. The analyzed results of the actual vegetation showed that willow community accounts for 37% of the area and rice field is 13.5%. As for animal ecology, total of 62 species and 25,977 individual wild birds were observed. After comparing and analyzing the RIS we compiled with the Ramsar Site designation standards, it turns out that the Jang-hang wetland meets criteria 1(biographic region), criteria 2,3 and 4(species and ecological communities) and criteria 5 and 6(water birds). Thus, Jang-hang wetland is eligible for the Ramsar site. As a result of establishing and evaluating the biotope types for setting management areas, Jang-hang wetland has a total of 13 different types, and the grade I represents 75.4% of the area while the grade III 0.8% of the land status. We categorized four management zones for the wetland depending on the biotope patterns - preservation, restoration, use and buffer zones and suggested management methods for each zone.

• Journal of Korean Society of Forest Science
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• v.83 no.3
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• pp.410-423
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• 1994

Seasonal and diurnal changes of stomatal diffusive resistance(S.D.R.) and transpiration rate(T.R.) were investigated for determining the ecophysiological water relations of economic tree species subjected to chronic water stress or exogenous abscisic acid treatment. Four species of oaks including Quercus serrata, Q. mongolica. Q. acutissima, and Q. variabilis were used as the experimental materials and also Fraxinus rhynchophylla was studied together with oaks. Stomatal diffusive resistances were repeatedly measured on the containerized 1-0 year seedlings subjected to two kinds of soil moisture regime (wet and dry) in June, August, and September by LI-1600 Steady State Porometer of LI-Cor, Inc.. Exogenous abscisic acid (ABA) solutions of 0.5 mM and 0.05 mM in July and August, respectively, were absorbed into shoots cut from the containerized seedlings for determining their effects on stomatal behavior and transpiration. Most of measurements in stomatal diffusive resistance maintained about 5 s/cm in the morning after sunrise despite of different treatments. But the values fluctuated frequently to high level above 20 s/cm through the afternoon until sunset in the seedlings subjected to dry soil moisture regime. Despite of various treatments and environmental conditions, stomatal diffusive resistances of Q. variabilis were more stable than those of Q. serrata or Q. acutissima. Their values of F. rhynchophylla changed more irregularly in comparison with those of oak species. Exogenous abscisic acid absorbed into shoots cut from seedlings increased stomatal diffusive resistance obviously in most of the species studied. The stomatal responses to abscisic acid treatment were more sensitive in July especially in Q. serrata than in Q. variabilis and Q. acutissima. But the effects of ABA treatment were presented more remarkably in Q. acutissima in August. The responses to abscisic acid were not certain in F. rhynchophylla because of their various fluctuation patterns.