• 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.

• Korean journal of applied entomology
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• v.41 no.1
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• pp.61-65
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• 2002

This study was conducted to investigate percentage of parasitism and control effect of Liriomyza trifolii by Hemiptarsenus zilahisebessi on tomato. Percentages of parasitism on L. trifolii larva by ectopatasitoids war e 26∼45% Among them the parasitism by H. zilahisebessi was highest as 47∼75% in tomato. The parasitoids preferred 1 st to 3rd instar of host larvae. In laboratory test, the parasitoids showed high parasitism on 3rd instar larvae of host by 89.8∼93.1% when the female parasitoids were introduced by the ratios of 1 : 10, 1 : 20, and 1 : 30. In field test, 3 or 5 female parasitoids were introduced per plant. In the case, the parasitism increased to 80% 4 weeks after introduction of the parasitoids. This increased parasitism was resulted from density reduction of the host larvae There were no significant differences in parasitism, density of alive host, and percentage of damaged leaf between inoculation density.

• Korean Journal of Soil Science and Fertilizer
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• v.25 no.4
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• pp.387-393
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• 1992

The fate of inoculum strain of Bradyrhizobium japonicum was studied by using genetically marked strain. RJB6 $str^rnal^rneo^r$. A spontaneous mutant of B. japonicum isolated from nodules was made to have antibiotic resistance against streptomycin and nalidixic acid. In order to make genetically marked strain, neomycine resistant gene(Tn5) was introduced into this spontaneous mutant by conjugation with E. coli containing pSUP2021. The southern hybridization was carried out to confirm the plasmid insertion. Hybridization of chromosome DNA using pSUP2021(Tn5) as a probe showed that Tn5 was located on the 4.9kb fragment of chromosome. Soybean seeds were planted into a soil previously cultivated with soybean and inoculated with different cell densities of marked strain. Fourty days after planting, the inoculation effects on nodule number, nodule fresh weight, plant height and nitrogen content in the plot inoculated with heavy cell suspension was a little better than those in the plot with low inoculation. The recovery percentage of the marked strains was about 12% in the plot inoculated with heavy density cell suspension, while 5% in the plot inoculated with low cell suspension.

• Korean Journal of Environmental Agriculture
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• v.17 no.3
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• pp.254-259
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• 1998

This study was focused on finding out the potential problems associated with organic farming system. The effect of composted animal manures subsequent inoculation of microbes on growth and yield of tomatoes (Lycopersicon esculentum Mill. 'Minicarol') were examined to develop a proper organic farming practice. Plant heights were greater in composted manure treatment than in conventional practice, whereas widths of leaves were higher in conventional field. Chlorophyll contents between various amount of composted manure application were gradually decreased and showed no significant differences after 45 days of planting. The yield in the treatment applied 12 ton of composted animal manure per 10a as pre-planting fertilizer and following microbial inoculation were only 50-60% compared to that of conventional farming. However, yield increased up to 80% when additional composts were applied to the treatment received 6 ton of composted animal manure per 10a in the middle of cultivation. Microbial inoculation followed by composted manure application induced rapid decrease of nitrogen content in soil. However, the density of microorganisms was significantly increased. Tomatoes produced through organic farming were clear in color, Further, soluble solid and acid content were increased. The highest level of acid and solids were observed in the treatment applied 12 ton of digested swine manure per 10a. Although nitrogen content including ammonium and nitrate rapidly increased after application of composts, these were significantly reduced approximately 4-5 weeks after planting. The level of phosphorus, potassium, magnesium and calcium showed gradual decrease compared to nitrogen.

• Korean Journal of Soil Science and Fertilizer
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• v.25 no.1
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• pp.77-88
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• 1992

Effective strains of cowpea bradyrhizobia JB7 $nal^rspe^r$ and CB756 $str^rrif^r$, antibiotic-resistant variants of JB7 and CB756, respectively, were used to examine changes of rhizosphere populations and nodule occupancy. Populations of each strain increased gradually in the rhizosphere, reaching a maximum of about $10^8$ cells per root system. Nodule number increased as the density of inoculum increased from $10^2$ cells to $10^8$ cells per seed. Inoculation with liquid suspension resulted in the formation of more nodules than the peat slurry or granule inoculation. When JB7 $nal^rspe^r$ and CB756 $str^rrif^r$ were introduced in equal numbers in inoculum mixtures the former consistantly occupied the majority of nodules with all three groundnut cultivars used. There was no difference in yield between nitrogen treatments and inocultation treatments.

• Journal of the Korea Organic Resources Recycling Association
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• v.27 no.4
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• pp.51-59
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• 2019

In this study, the influence of anaerobic digested sludge and 50 mM PBS (phosphate buffer solution) mixing ratio (1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7) on hydrogen production and inoculation period were examined. MECs were operated in fed-batch mode with an applied voltage of 0.9 V. As a result, in the 1:1 mixing ratio reactor, 9.8-20.9 mL of hydrogen was produced with the highest hydrogen content of 66.8-79.6%. Hydrogen gas production and power density increased from after 12 days of inoculation for the 1:1 mixing ratio reactor. In case of 1:2, 1:3 and 1:4 mixing ratio reactor, the hydrogen gas production was 3.7-7.1 mL and the hydrogen gas content was 5.8-65.8%. The hydrogen gas yield in 1:5, 1:6 and 1:7 ratio reactors, was 0.50-0.69 mL and hydrogen content range was 1.8-7.1%. The mixing ratio was found to be suitable for hydrogen production and inoculation period by mixing ratio up to 1:4.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.32 no.2
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• pp.173-180
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• 1987

Symptom development and disease severity of Phytophthora blight in the sesame plants varied depending upon age of the plants tested, inoculation method, watering method, and inoculum density in both susceptible Suweon 9 and Suweon 26 and moderately resistant B-67 and IS 103 sesame lines to Phytophthora nicotianae var. parasitica when inoculated. However, successful differentiation of the sesame lines for varietal resistance was possible using 20-day old seedling, inoculation by soil infestation, saturated soil water condition by half immersion of pots in water tank, and 200 sporangia per one ml of inoculum. Spraying or soil inoculation to 70-day old plants also was effective in differentiating the varietal resistance. By the screening method Suwon 26 showed 100％ diseased plants and symptom severity index 9.0, while B-67 showed 20% diseased plants and symptom severity index 1.7. The rating scale given was from 0 through 9. For example, the scale 0 signified no symptom development, 5 signified discoloration of basal part of stem, and 9 signified discoloration of stem more than 10 cm high above the soil surface with blighted leaves. Differentiation in symptom severity also was made by percentage of the lesion area. Results evaluated using both parameters were well corresponded in varietal reaction of sesame to Phytophthora blight.

• Journal of Mushroom
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• v.13 no.3
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• pp.256-261
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• 2015

This study was conducted to reduce contamination ratio of oyster mushroom bottle cultivation. The optimal conditions of substrate sterilization for reducing of contamination ratio were at $121^{\circ}C$ for 90 min. In addition, UV-C irradiation is good for lower contamination ratio to continue over 6 hours at cooling and inoculation room after sterilization. The contamination ratio and density of microorganisms of substrate were showed 0% after sterilization at $121^{\circ}C$ for 90 min. Trichoderma sp., main pathogen of mushrooms, was detected from substrate after sterilized during 2 or 4 hours at $101^{\circ}C$ and $105^{\circ}C$, respectively. The amount of electricity used was the lowest at $121^{\circ}C$ for 90 min than that of other sterilization conditions. The UV-C irradiation treatment was used UV-C lamp(40 watts) in the inoculation room($56m^3$). The density of bacteria did not detected after UV-C irradiation for 6 hours. And the death ratio of bacteria and Trichoderma sp. was 99.9% after UV-C irradiation for 6 hours. However, in the same UV-C irradiation time, the death ration of Cladosporium sp. was 90.9%. Therefore, the death ratio of fungi was lower than that of bacteria at the same UV-C irradiation treatment.

• Korean Journal of Soil Science and Fertilizer
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• v.25 no.1
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• pp.99-107
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• 1992

Effects of the indigenous Vesicular-arbuscular mycurrhizal fungi(VAMF) on early growth response of greenhouse grown crops were experimented. This study was done to evaluate the benefit of indigenous VAMF inoculation on the early growth and the subsequent growth after transplanting of some crops such as cucumber, tomato, hot pepper, eggplant, and melon. Leaf area, shoot dry weight, and plant length of mycorrhizal greenhouse crops showed the tendency of significant or no significant increase over control plants receiving no inoculation. The levels of VA mycorrhizal colonization were increased with plant growth, and infection rates of horticultural crop except hot pepper around one week after transplanting were decreased, while that of 8 weeks after emergence of mycorrhizal seedlings were increased again and infected by around 50% at harvesting time. In spore densities in the rhizosphere soil of craps experimented, the number of spore ranged from $72.7{\pm}26.3$ to $100{\pm}10.3g^1$ on dried soil basis and high density showed in both cucumber and tomato. Total nitrogen contents in shoots were lower in the mycorrhizal plants than non-mycorrhizal one, whereas P uptake in mycorrhizal hot pepper and tomato were highly ramarkable. The K contents in the shoots of mycorrhizal cucumber and eggplent were highly enhanced. Inoculation of the indigenous VAMF enhanced shoot Ca and Mg in both tomoto and melon. The contents of Fe, Zn, Mn and Cu in shoots of mycorrhizal crops were higher than non-mycorrhizal plants and vice versa in case of eggplent. Inoculation of the indigenous VAMF to horticultural crops were effective for alleviation of transplanting shock, and pretransplanting infection improved subsequent growth by reducing the time required for establishment of a functional mycorrhizal symbiosis following transplanting.

• Journal of Sericultural and Entomological Science
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• v.25 no.2
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• pp.1-31
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• 1984

Flacherie, as one of the most prevalent silkworm diseases, causes severe economic damage to sericultural industry and its pathogens have been proved to be flacherie virus (FV) and densonucleosis virus (DNV). Multiplications of the viruses in the larvae of the silkworm, Bombyx mori, were studied by the sucrose density gradient centrifugation and electron microscopy. The quantitative and qualitative changes of nucleic acids and proteins were investigated from the midgut and hemolymph in the silkworm larvae infected separately with FV and DNV. The histopathological changes of epithelial cells of infected midgut also were examined by an electron microscope. 1. Purified fractions of FV or DNV in a sucrose density gradient centrifugation yielded one homogenous and sharp peak without a shoulder, suggesting no heterogenous materials in the preparation. Electron microscopy also revealed that FV and DNV were spherical particles, 27nm and 21nm in diameter, respectively. 2. Silkworm larvae showed a decrease in body weight on the 6th day and in midgut weight on the 3rd day after inoculation with FV or DNV. 3. DNA content was higher in the midgut when infected with FV or DNV, but the hemolymph of the infected larvae showed no difference during first 6 days after inoculation, after which DNA concentration declined rapidly. 4. RNA synthesis of silkworm larvae infected separately with FV and DNV was stimulated in the midgut, but RNA content was reduced in the hemolymph at the early stage of virus multiplication. At the late stage of virus multiplication, however, it was extremely reduced in both midgut and hemolymph. 5. The concentration of protein in the midgut and hemolymph of silkworm larvae infected separately with FV and DNV showed no difference from that of the healthy larvae at the early stage of virus multiplication, but it was significantly reduced at the late stage of virus multiplication. 6. There was no difference in the electrophoretic patterns of RNAs extracted from the midgut of healthy or virus-infected larvae. 7. The electrophoresis of proteins extracted from the midgut infected with FV or DNV, when carried out on the 1st and 5th day after virus inoculation, showed no difference from that of the healthy larvae. But, there was an additional band with medium motility in the proteins on the 8th day after virus inoculation, while a band with low mobility shown in the proteins of healthy larvae disappeared in the infected larvae. However, a band with high mobility in the healthy larvae was separated into two fractions in the infected larvae. 8. The electrophoretic pattern of hemolymph proteins of the silkworm larvae infected separately with FV and DNV was similar to that of the healthy larvae, but the concentration of hemolymph proteins in the infected larvae was lower than that of the healthy larvae at the late stage. 9. Two types of inclusion bodies were shown by the double staining of pyronin-methyl green in the columnar cell of the midgut on the 8th day after FV inoculation. 10. Electron microscopy of the infected midgut revealed that the 'cytoplasmic wall' of the goblet cell thickened on the 5th day after FV inoculation and several types of the cytopathogenic structures, such as virus$.$specific vesicles, virus particles, linear structures, tubular structures, and high electron-dense matrices were observed in the cytoplasm of the goblet cell. The virus particles were also observed in the microvilli and the structures similar to spherical virus particles were observed around the virus-specific vesicles, suggesting the virus assembly in the cytoplasm. 11. Fluorescence micrograph of the infected midgut stained with acridine orange showed that the nucleus, the site of DNV multiplication in the columnar cell, enlarged on the 5th day after virus inoculation. 12. Electron microscopic examination of DNV infected midgut revealed that the nucleolus of the columnar cell was broken into granules and those granules dispersed into apical region of the nucleus on the 5th day after virus inoculation. On the 8th day after inoculation, it was also observed that the nucleus of the columnar cell was full with the high electron-dense virogenic stroma which were similar to virus particles. These facts suggest that the virogenic stroma were the sites of virus assembly in the process of DNV multiplication.