• KOREAN JOURNAL OF CROP SCIENCE
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• v.23 no.3
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• pp.5-11
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• 1978

Since 1970, herbicides have been widely used in the crop production, especially in paddy field in Korea. In 1978, both preemergence and postemergence type herbicides are applied in the approximately 70% of total paddy field and 15% of upland to control weeds. Most herbicides control annual weeds effectively, but perennials have been problems in the paddy field. Under upland conditions, effectiveness of herbicides varies depending on many environmental conditions (soil moisture, soil physical properties, temperature, etc.) as well as uniform application of appropriate amounts of herbicides. In Korea, many research works have been concentrated on the screening of new herbicides in terms of herbicide effectiveness and yield or phytotoxicity of crops, and especially on the paddy field. However, physiological aspects of herbicidal action in plant and interaction of herbicides with the environments have not been studied approximately. Therefore, researches on the uptake of herbicides and the influence of herbicides on the physiological phenomena such as photosynthesis, respiration, nutrient uptake etc., to control troublesome perennial weeds in the paddy field are needed in future. Also some researches are needed to improve effectiveness of herbicirdes under upland conditions.

• Journal of the Korean Society of Visualization
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• v.8 no.4
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• pp.48-53
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• 2010

Water-uptake through roots, is an essential process of the water flow in plants. Its visualization is very useful for understanding sap flow dynamics at whole plant level. In this study, the tips of Arabidopsis' root hairs were excised and exposed to repeated dehydration and rehydration processes. The water-refilling through individual xylem vessels was visualized using the synchrotron X-ray micro-imaging technique. The high temporal resolution ($2\;{\mu}m$) and beam intensity of the X-ray source allowed to acquisition of consecutive X-ray images of the water-refilling process up to 10 frames/sec. Various flow patterns were observed and the ascending speed of the water-air interfaces was analyzed. The relation between the water-rising height and ascending speed was also analyzed. The present results would provide better alternative for investigating sap flows in roots.

• Nuclear Engineering and Technology
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• v.14 no.3
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• pp.116-121
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• 1982

The uptake and retention of strontium-90 from seawater by the seaweed Undaria pinnatifda(sea mustard) varied depending on the plant part, exposure time, salinity, contents of stable strontium and calcium, and presence of chelating agent in the seawater. The concentration factors attained at equilibrium were in the range of 50 and it was evident that the bioaccumulation was largely due to the adsorption of the radionuclide on the surface of seaweed.

• Korean Journal of Organic Agriculture
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• v.3 no.1
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• pp.79-85
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• 1994

Worm cast is one of the effective and the least harmful organic fertilizer. The purpost of this work is to elucidate the physiological role of worm cast in the plant growth. Worm cast extract contains 17.83ppm of zinc, but either cadmium or lead were not detected in it. Cucumber (Cucumis sativus L. cv. H. N. Semiwhite) was germinated and incubated with percentage-varied extract. While 10% extract stimulated sprouting of seeds, 100% extract had no effct on it. 50% extract and 100% extract enhanced hypercotyl elongation and fresh weight most effectively. Dry matter and zinc concentration in hypercotyl were increased as percentage of extract increased. Protein con-tent was not affected by extract, 100% extract inhibits water uptake of seedling. Considering these, enhancement of seedling growth was mainly based on increment of water uptake.

• Mycobiology
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• v.46 no.4
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• pp.388-395
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• 2018

Radionuclides were deposited at forest areas in eastern parts of Japan following the Fukushima Daiichi Nuclear Power Plant incident in March 2011. Ectomycorrhizal (EM) fungi have important effects on radiocaesium dynamics in forest ecosystems. We examined the effect of colonization by the EM fungus Astraeus hygrometricus on the uptake of cesium (Cs) and potassium (K) by Pinus densiflora seedlings. Pine seedlings exhibited enhanced growth after the EM formation due to the colonization by A. hygrometricus. Additionally, the shoot Cs concentration increased after the EM formation when Cs was not added to the medium. This suggests that A. hygrometricus might be able to solubilize Cs fixed to soil particles. Moreover, the shoot K concentration increased significantly after the EM formation when Cs was added. However, there were no significant differences in the root K concentration between EM and non-EM seedlings. These results suggest that different mechanisms control the transfer of Cs and K from the root to the shoot of pine seedlings.

• Korean Journal of Soil Science and Fertilizer
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• v.34 no.2
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• pp.110-116
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• 2001

This experiment was carried out to investigate the effects of amount of nitrogen application with the barley straw application on the changes in soil physical and chemical properties. nutrient uptake and percentage recovery of chemical fertilizer N in the rice plant from 1997 to 1998. The soil physical properties, such as bulk density, hardness, porosity and gaseous phase were improved by barley straw application. There was also improvement or increment in the soil chemical properties, such as pH, organic matter, T-C. T-N, available $SiO_2$, exchangeable K and cation exchange capacity, but decrease in available $P_2O_5$. The $Fe^{+{+}}$ content in soil after barley straw application was high from tillering stage to panicle forming stage, but becoming lowered toward the heading stage, while $Mn^{+{+}}$ content was increased. N uptake with barley straw application was increased in the N $126kg\;ha^{-1}$ plot, but decreased in the N $141kg\;ha^{-1}$ plot. The uptake of fertilized N was continued longer in barley straw application than none-application plot. Percentage recovery of chemical fertilizer N in rice straw was around 1% at tillering stage, but was highly increasing till maximum tillering stage, while the recovery was generally low in barley straw application. Meanwhile, fertilizer P uptake in barley straw application was high, but potassium uptake was low at all different levels of N application.

• Korean Journal of Soil Science and Fertilizer
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• v.40 no.4
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• pp.280-291
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• 2007

Much research has been conducted in the field of phytoremediation since the discovery of the range of plants known as hyperaccumulators. Research has focused simultaneously on elucidating the mechanism of metal(loid) accumulation and development of practical techniques to enhance accumulation efficiency. To date, it is generally understood that there are five specific mechanisms employed by hyperaccumulating plant species that are either not or under utilized by non-hyperaccumulators. These include 1) enhanced metal(loid)s uptake through the root cell, 2) enhanced translocation in plant tissue, 3) detoxification and sequestration, 4) enhanced metal availability in soil:root interface, and 5) active root foraging toward metal(loid) enriched soils. Among these mechanisms, understanding of the plant-root effect on metal(loid) dynamics and subsequent plant uptake is vital to overcome the inherit limitation of phytoremediation caused by low metal(loid) solubility in soils. Plant roots can influence the soil chemistry in the rhizosphere through changes in pH and exudation of organic compounds such as low-molecular-weight organic acids (LMWOAs) which consequently change metal(loid) solubility. The decrease in soil pH by plant release of $H^+$ results in increased metal solubility. Elevated levels of organic compounds in response to high metal soil concentrations by plant exudation may also increases metal concentration in soil solution through formation of organometallic complexes.

• Korean Journal of Soil Science and Fertilizer
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• v.4 no.2
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• pp.143-147
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• 1971

Field experiments were carried out to determine the effect of B on rape with application of lime and compost in sandy upland soil and in clayey paddy soil. The plant samples from each treatment at flowering stage were analyzed to interpret the yield response. The effect of B was very significant in both soils, but more marked in sandy upland soil. The application of 20kg/ha borax appears to increase upto the possible level that can be achieved by B application. Application of 40kg/ha borax did not give any further additional response. In acidic paddy soil (pH 5.4), the effect of B was fully exhibited only with liming. Liming neither intensified the B deficiency nor reduced the B content in the plant tissue, but rather promoted the growth of rape plant. There was highly significant negative correlation between Ca/B ratio and seed yield ($r=-0.74^{**}$), but it was very difficult to draw a line between normal and deficient Ca/B ratio. It is very interesting that boron application significantly increased the Ca uptake in no lime treatment. Application of compost was generally inffective and did not affect the B supply to the plant. However, it appears to increase K uptake slightly and give a little favorable effect on growth of plant.

• Korean Journal of Soil Science and Fertilizer
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• v.9 no.4
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• pp.223-233
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• 1976

The potassium equilibrium activity ratio ($AR^k_e$) and energies of exchange for replacement of ca+Mg by K ($E_k$) were measured for seven paddy soils to investigate their correlations with the exchangeable K (Kex) and uptake of K at different growth stages of rice plant. It was found that $AR^k_e$ had highly significant correlations at 1% level with uptake of K at maximum tillering, heading and harvesting stages, and also with Kex in soils at maximum tillering stage. The larger $AR^k_e$ of soils, the more uptake of K by rice plant. The fact indicates that uptake of K by the plant can be characterized in terms of $AR^k_e$ or energy of exchange of soils. In aspect of energy of exchange, higher uptake of K and yield of grain were observed from -2500 to -3000 calories per chemical equivalent, representing suitable balances between K and Ca+Mg in soils. Low uptake of K was observed at the energies of exchange below -3500 calories per chemical equivalent, which were prevalent in the ordinary acidic soils. From the correlations between energy of exchange and Kex, it can be concluded that at least 0.37 meq. of exchangeable K should be existed in 100g of dried acidic soil to keep suitable balances of K and Ca+Mg. The result shown that application of K adsorbed zeolite to paddy soils increased $AR^k_e$ and consequently brought about higher K uptake and grain yield. Therefore, a reasonable way recommended to get good balance of exchangeable K in the soil is applying 1.7 tonns of K adsorbed zeolite containing 60kg $K_2O$ per hectare.

• Korean Journal of Soil Science and Fertilizer
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• v.19 no.2
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• pp.147-151
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• 1986

A study was carried out to investigate yield, yield components, and change of chemical components in rice plants grown under different concentration of lead compound in nutrient solution of sandy culture. The results obtained are as follows. 1. Increasing lead concentration in culture solutions, pb content in the plant was increased and crop yields were decreased. 2. The critical pb concentration at which yield was declined, was 13.6 ppm. 3. As adding higher concentration of lead in nutrient solutions, concentration of lead in rice plant was significantly increased on leaf blade, and brown rice in pb. 4. Yield loss was closely related to pb content in leaf blade.