• Applied Biological Chemistry
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• v.40 no.4
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• pp.329-333
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• 1997

Phosphate solubilizing microorganisms (1,000 bacteria and 200 fungi) were isolated from soil around Kyungnam and Kyungbook regions using potato dextrose agar-calcium phosphate medium. A fungus with the greatest phosphate solubilizing activity was selected and identified to Penicillium sp. GL-101, based on the morphological characteristics of conidiophore and conidia; flask shape of phialide, simple branching type of conidiophore, and columnar shape of conidial head, in malt extract agar and potato dextrose agar media. The optimum temperature and initial pH to solubilize rock phosphate in potato dextrose broth-rock phosphate medium were $25^{\circ}C$ and pH 7.5, respectively. In these optimum conditions, phosphate solubilizing activities of Penicillium sp. GL-101 against four types of insoluble phosphate: tricalcium-phosphate, aluminium phosphate, hydroxyapatite and rock phosphate, were quantitatively determined. As results, this fungus highly discharged free phosphates to the culture broth with the concentrations of 1,152 ppm against tricalcium-phosphate, 565 ppm against rock phosphate, 292 ppm against aluminium phosphate, and 217 ppm against hydroxyapatite, respectively.

• Korean Journal of Soil Science and Fertilizer
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• v.38 no.4
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• pp.180-187
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• 2005

Nine chemolithoautotrophic and 12 chemolithoheterotrophic sulfur oxidizing bacteria were isolated using enrichment technique in modified Starkey's medium. All isolates reduced pH of the growth medium through oxidation of elementai sulfur to sulfuric acid. Isolates utilized the thiosulfate as energy source except LCH. None of the isolates grew anaerobically and utilization of glucose was found only in chemolithoheterotrophic isolates SGA6 and JIG. In vitro sulfate production from elemental sulfur was found maximum for chemoiithoautotroph LCH ($43.2mg\;100\;mL^{-1}$) and least for chemolithoheterotroph JIG ($10.04mg\;100\;mL^{-1}$). The above tests suggested that all isolates belong to the member of Thiobacillus. For field inoculation of Thiobacillus, clay based pellet formulation was developed with the cell load of $2.5{\times}10^7cfu\;g^{-1}$ of pellet. It is easy to handle by the farmers and more likely to lead to successful farming.

• Economic and Environmental Geology
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• v.34 no.4
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• pp.355-373
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• 2001

Palaeomagnesim of Paleozoic Tuwibong Type Sequence in Yemi area was studied with a total of 256 core-samples collected from 23 sites. The study area (geographical coordinates: 37.l8$^{\circ}$N, l28.610E) is located between Taebaek and Yongwol belonging to the northeastern part of the Okchon Belt. Thermal cleaning was a most effective method to extract stable characteristic remanent magnetization (ChRM) direction, even though AF cleaning also worked on some specimens. Mean ChRM direction of the Cambrian Hwajol Formation was different from the present-day field direction and showed maximum clustering (max. k value) at 100% bedding-tilt correction. However, it could not pass the fold test. Ordovician Makkol and Kosong Limestones as well as Permian Sadong and Kobangsan Formations have very weak NRM, and were remagnetized into the present-day field direction. ChRM directions from the Carboniferous Hongjom Formation passed both fold and reversal tests. IRM experiments and blocking temperature spectrum indicate that both magnetite and haematite are carrier of the primary magnetization. Palaeomagnetic pole position from the Carboniferous Hongjom Formation is very similar to that of contemporary North China Block (NCB) suggesting that the study area was a part of, or located very near to, the NCB during Carboniferous.

• Korean Journal of Soil Science and Fertilizer
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• v.41 no.1
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• pp.18-25
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• 2008

Pseudomonas sp. PRGB06, a bacterial strain isolated from diamondback moth (Plutella xylostella) gut, was examined for its plant growth promotion and biofertilizing traits. The bacteria growth was observed under various conditions of carbon sources, temperature, pH and salt concentrations. In addition, the mechanisms of antagonism and phosphate solubilization were investigated. The bacterial strain PRGB06, grew well using most of the tested carbon sources. The best growth was observed at $30^{\circ}C$ and pH 7. The inhibition of the pathogenic fungi was likely due to the volatile antifungal metabolite and ammonia gas produced by the bacteria. A significant positive relationship was found between the phosphate solubilization and acid production. When inoculated with PRGB06 in vitro and in gnotobiotic condition, red pepper and maize showed increase in root length, seedling vigor and dry bio-mass.

• Korean Journal of Soil Science and Fertilizer
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• v.36 no.4
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• pp.233-238
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• 2003

The effect of phosphate solubilizing microbes (PSM) on plant P uptake and growth in rock phosphate applied soil was tested under a greenhouse condition. Tobacco plants were grown in nonsterilized soil inoculated with Penicillium oxalicum CBPS-3F-Tsa with or without rock phosphate application as P fertilizer. Phosphorus concentration in tobacco plants was increased by the application of rock phosphate, while inoculation of soil with fungi further significantly increased P concentration in tobacco plants compared with the noninoculated treatments. Phosphorus uptake by tobacco plants was also increased by the application of rock phosphate and PSM inoculation, and the significant comparison has been made with single rock phosphate treatment. Growth of tobacco plant was also significantly increased in the treatments receiving rock phosphate, while the combined application of rock phosphate and PSM further increased plant growth. It was concluded that the positive effect of PSM inoculation on plant growth was closely related in plant P content and uptake. These results suggest that Penicillium oxalicum CBPS-3F-Tsa could solubilize insoluble soil phosphates and rock phosphate which can promote growth and P uptake of tobacco plants.

• Applied Biological Chemistry
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• v.35 no.6
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• pp.449-456
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• 1992

Expermient were conducted to determine the effect of phosphorus stress on bacteroid content and energy status of soybean (Glycine max [L.] Merr.) nodules. Plants inoculated with Bradyrhizobium japonicum MN 110 were grown with P-stressed (0.05 mM-P) and control (1 mM-P) treatment in the greenhouse. Phosphorus stress decreased nodule mass per plant and nodule mass to whole plant mass ratio. Phosphorus concentration in leaf, stem and root tissues were reduced by 75% but in nodule tissue was reduced only by 40% under phosphorus stress during 3 week experimental period. The bacteroid content per unit nodule mass and the distribution of total nitrogen and total phosphorus among the bacteroid and plant cell fractions of nodule were not affected significantly by phosphorus stress. Regardless of phosphorus treatment, 22% of the nitrogen and 27% of the phosphorus in whole nodules were associated with the bacteroid fraction. The ATP and total adenylate concentrations in and energy charge of whole nodule were decreased 77%, 46% and 37%, respectively, by phosphorus stress. The ATP concentration in and energy charge of the host plant cell fraction of nodules were decreased 86% and 59%, respectively, but these parametres in bacteroid in nodules were not affected by phosphorus stress. These results indicated that nodule is a strong phosphorus sink and that nodule growth and development are regulated to maintain a high phosphorus and energy content in bacteroid even when the host plant is subjected to phosphorus deficiency.

• Korean Journal of Soil Science and Fertilizer
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• v.25 no.2
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• pp.160-167
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• 1992

The growth of weeds and some other plants has been considered to be inhibited by sicklepod(Cassia tora L.) sharing the habitat. The study was conducted, for the first time, to propose that this phenomenon is not only due to competition for physical and nutritional conditions but also due to allelopathy. In addition, autotoxicity of sicklepod was examined. The results are summarized as follows. 1. Rice sheath length reduced progressively from 18 % to 36 % with increasing the concentration of treating aqueous extracts of sickle pod seeds, but rice germination was not affected. In contrast, radish hypocotyl length was not reduced by the aqueous extract treatment but radish germination was significantly reduced by 66 % at 1 : 10 and 1 : 5 treatment. 2. Total chlorophyll contents in rice seedling decreased from 50 % to 65 % by treatment of seed aqueous extracts diluted from 1 : 50 to 1 : 5 ratio. 3. Aqueous extracts of sicklepod leaves significantly reduced hypocotyl length and fresh weight in radish and germination in rice, but mung bean was slightly affected by aqueous extracts only in fresh weight. 4. Volatiles from fresh, immature seeds with husk reduced the radish germination and seedling growth and radish root growth appeared to be more sensitive to the exposure to volatiles from fresh immature seeds than both germination and hypocotyl growth. 5. Volatiles from sickepod leaves inhibited germination and growth of radish, rice and mung bean, and seedling growth was more sensitive to volatiles from leaves than germination. 6. Volatiles from sicklepod leaves reduced germination and radicle length of sicklepod itself. 7. Collectively, it is concluded that there are water-soluble and volatile substances responsible for allelopathy in sicklepod.

• Applied Biological Chemistry
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• v.40 no.3
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• pp.232-237
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• 1997

Soybean plants inoculated Bradrhizobium japonicum MN 110 were grown in outdoor perlite pots with nitrogen free nutrient solution containing 1.0 mM-P(control) and 0.05 mM-P(stress) and harvested at 28, 35, 42 and 49 days after transplanting (DAT) to examine the effect of phosphorus deficiency on ureide concentration of and distribution to diffrent plant organ in nitrogen fixing soybean plant during the vegetative growth. Total dry mass of control plants increased 8.9 fold and that of phosphorus deficient plant increased 2.7 fold during the experimental period. Phosphorus deficiency reduced total phosphorus and nitrogen accumulation by 80%,40% respectively, at 28 DAT and 93%, 84%, respectively, at 49 DAT. Nitrogen concentration was reduced by phosphorus deficiency in all tissues with leaf and stem tissues affected to a greater degree than nodule and root tissues at every sampling date. Phosphorus deficiency significantly reduced soluble reduced-N and ureide-N concentration in leaf and stem but did not affect those in root. The proportion of soluble reduced-N in leaf was reduced from 60% to 50% but increased from 10% to 20% in the roots. The proportion of ureide-N in leaf of control plants was higher than that in phosphorus deficient plants, whereas, roots of phosphorus deficient plants contained a higher propotion of ureide-N than those of control plants. These indicated that phosphorus deficiency not only inhibit nitrogen fixation of nodules but also restrict the translocation of fixed nitrogen out of the root system into the xylem.(Received April 4, 1997; accepted May 2, 1997)

• Applied Biological Chemistry
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• v.40 no.2
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• pp.134-138
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• 1997

The objective of this study was to examine the effect of phosphorus deficiency on nitrogen fixation and photosynthesis of nitrogen fixing soybean plant under $CO_2$ enrichment condition. The soybean plants(Glycine max [L.] Merr.) inoculated with Bradyrhizobium japonicum MN 110 were grown with P-stressed(0.05 mM-P) and control(1 mM-P) treatment under control$(400\;{\mu}l/L\;CO_2)$ and enrichment$(800\;{\mu}l/L\;CO_2)$ enviromental condition in the phytotron equipped with high density lamp$(1000\;{\mu}Em^{-2}S^{-1})$ and $28/22^{\circ}C$ temperature cycle for 35 days after transplanting(DAT). At 35 DAT, phosphorus deficiency decreased total dry mass by 64% in $CO_2$ enrichment condition, and 51% in control $CO_2$ condition. Total leaf area was reduced significantly by phosphorus deficiency in control and enriched $CO_2$ condition but specific leaf weight was increased by P deficiency. Phosphorus deficiency significantly reduced photosynthetic rate(carbon exchange rate) and internal $CO_2$ concentration in leaf in both $CO_2$ treatments, but the degree of stress was more severe under $CO_2$ enrichment condition than under control $CO_2$ environmental condition. In phosphorus sufficient plants, $CO_2$ enrichment increased nodule fresh weight and total nitrogenase activity(acetylene reduction) of nodule by 30% and 41% respectively, but specific nitrogenase activity of nodule and nodule fresh weight was not affected by $CO_2$ enrichment in phosphorus deficient plant at 35 DAT. Total nitrogen concentrations in stem, root and nodule tissue were significantly higher in phosphorus sufficient plant grown under $CO_2$ enrichment, but nitrogen concentration in leaf was reduced by 30% under $CO_2$ enrichment. These results indicate that increasing $CO_2$ concentration does not affect plant growth under phosphorus deficient condition and phosphorus stress might inhibit carbohydrate utilization in whole plant and that $CO_2$ enrichment could not increase nodule formation and functioning under phosphorus deficient conditions and phosphorus has more important roles in nodule growth and functioning under $CO_2$ enrichment environments than under ambient condition.

• Applied Biological Chemistry
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• v.34 no.2
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• pp.117-124
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• 1991

Soybean plants inoculated with Bradyrhizobium japonicum MN 110 were supplied with nutrient solutions containing 1.0, 0.25 and 0.5.nM-P to characterize the effect of externaI-P supply on the phosphorus status of nodules and on the P-uptake system of isolated bacteroids from nodules. After 48 days of growth, whole plant dry mass in the 0.25 and 0.05 mM-P treatments decreased significantly. The Pi concentrations in nodules were 4.1, 2.5 and 2.0 mM for 1.0, 0.25 and 0.05 mM-P treatments, respectively. The external-P supply did not significantly affect the distribution of phosphorus among inorganic phosphate(Pi), soluble organic-phosphorus(SOP) and insoluble organic-phosphorus(TOP) fractions in nodules. The Pi concentrations in young leaves of 0.25 and 0.05 mM-P plants were 33% and 20% , respectively, of those in young leaves of 1.0 mM-P plants and Pi concentrations in old leaves were only 16% and 7%, respectively, of those in old leaves of 1.0 mM-P plants. Phosphorus deficiency decreased the percentage of total leaf phosphorus in the Pi fraction and increased the percentage of total leaf phosphorus in the IOP fraction. The bacteroid number ranged from 0.87 to $1.30{\times}10^{11}$ Per GFW nodule regardless of external-P supply to the host Plants and Plant age, The P-uptake rates were the same (15-16 pmoles /min./$10^8$ bacteroids) for the bacteroids isolated from nodules of 1.0 mM-P and 0.05 mM-P plants. These results indicate that Pi concentrations in nodules of phosphorus-deficient plants are sufficient for proliferation of bacteroids and that the P-uptake system of bacteroids is in a repressed state even when host plant growth is severely restricted by phosphorus-deficiency stress.