• Applied Biological Chemistry
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• v.34 no.2
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• pp.162-167
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• 1991

In an attempt to explore the mechanistic aspects of chilling injury in plants and their defensive measures against the low temperature stress, the time sequential measurements of pyruvate, superoxide radicals$(O_{\overline{2}})$ and antioxygenic enzymes during whole period of injury-inducing treatment were performed using mostly rice seedlings. Pyruvate was substantialy accumulated in leaf tissues during the exposure period to $5^{\circ}C$ of the seedlings ; the relative extent of the accumulation was increased with increasing time of the cold treatment. When the cold-treated plants were translocated to ambient temperature$({\sim}25^{\circ}C)$, the accumulation started to dissipate, concomitantly accompaning a remarkable increase in the $O_{\overline{2}}$ level of tissues. Superoxide dismutase(SOD) and catalase were also activated during post-chilling period, although they showed a considerable lag time for activation. In contrast, glutathione peroxidase, another antioxygenic enzyme in cells, was not activated at all by preceding cold treatment of plants. The uptake of exogenous $O_{\overline{2}}$ by the roots of rice seedlings resulted in increase in the activities of SOD and catalase in root tissues. The supply of $H_2O_2$ to plan st brought about the activation of catalase in situ, while failing to exert any effect on the activation state of glutathione peroxidase. The results obtained in this work suggest that pyruvate accumulation in cells is the direct cause of the overproduction of $O_{\overline{2}}$ and thereby other toxic activated oxygen species, and that SOD and catalase may play a crucial role in the protection of plant cells against active oxygen-mediated chilling injury.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.28 no.1
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• pp.81-88
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• 1983

This experiment was conducted to study about influenced inorganic element contents of flag leaf and chaff with different nitrogen and silicate application in Jinan (sea level 303m). The recommended rate of fertilizer application above N 15kg/10a was poor for dry production increment in cold in July elevation and was demanded increment of silicate. In the elevation of cold in July high rates of nitrogen application produced more incomplete grain and a reduced cold tolerance. These effects were due to over-content of soluble nitrogen within flag leaf and disturbance of uptaking potassium and silicate. On the other hand, the application of silicate could increase yield by promoting resistance to cold- damage. The application of increasing level of nitrogen resulted in increasing the contents of total nitrogen and phosphate in both sterile and fertile glumes. The contents of potassium and calcium were the highest at the level of nitrogen 10 - 15kg/10a, but magnessium was rather high at low nitrogen levels. It is interesting that at any level of nitrogen, over 6% higher silicate contents were noted in the fertile chaff than in the sterile chaff. Application of increasing level of silicate fertilizer decreased total nitrogen contents, but increased the contents of phosphate, potassium. and silicate in the chaff. Increasing rate of silicate content by increasing silicate addition was remarkably higher in the fertile chaff than in the sterile chaff.

• Journal of Korean Society for Atmospheric Environment
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• v.22 no.E2
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• pp.89-98
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• 2006

Two tobacco cultivars (Nicotiana tabacum L.), Bel-B and Bel-W3, tolerant and sensitive to ozone, respectively, were grown in a greenhouse supplied with charcoal filtered air and exposed to 200 ppb ozone for 4 hr. Effects on chlorophyll fluorescence, net photosynthesis, and stomatal conductance are described. Quantum yield was calculated from chlorophyll fluorescence and the initial slope of the assimilation-light curve measured by the gas exchange method. Only the sensitive cultivar, Bel-W3, developed visual injury symptoms on up to 50% of the $5^{th}$ leaf. The maximum net photosynthetic rate of ozone-treated plants was reduced 40% compared to control plants immediately after ozone fumigation in the tolerant cultivar; however, photosynthesis recovered by 24 hr post fumigation and remained at the same level as control plants. On the other hand, ozone exposure reduced maximum net photosynthesis up to 50%, with no recovery, in the sensitive cultivar apparently causing permanent damage to the photosystem. Reductions in apparent quantum efficiency, calculated from the assimilation-light curve, differed between cultivars. Bel-B showed an immediate depression of 14% compared to controls, whereas, Bel-W3 showed a 27% decline. Electron transport rate (ETR), at saturating light intensity, decreased 58% and 80% immediately after ozone treatment in Bel-B and Bel-W3, respectively. Quantum yield decreased 28% and 36% in Bel-B and Bel-W3, respectively. It can be concluded that ozone caused a greater relative decrease in linear electron transport than maximum net photosynthesis, suggesting greater damage to PSII than the carbon reduction cycle.

• Journal of the Korean Institute of Landscape Architecture
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• v.27 no.1
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• pp.122-131
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• 1999

Indoor environments are usually less than optimal for the growth of ferns, especially in regards to the water condition. These studies were performed to investigate responses involved in causing growth of ferns and presume management plan against the water deficit under indoor conditions. The effect of air humidity and soil moisture on the ferns was examined in Adiantume raddianum and Selaginella kraussiana. Results of experiments are as follows; 1. Under a low humidity condition, having a 25-50% RH. ornamental value of ferns decreased much more than under a 90% RH. Under a low soil moisture, such as sand treatment, ornamental value of ferns also decreased. 2. Leaf chlorophyll content, water content and stomata situations increased as air humidity and soil moisture went up. 3. Even if air humidity and soil water were not enough for ferns growth, the extending of irrigation cycle was helpful. 4. Under extremely low air humidity conditions, some water management, namely, using water holding soil or extending of irrigation cycle was desirable. Other methods of increasing air humidity, including water instruments such as ornamental pools, waterfalls, or fountains, grouping plants together were also helpful. But spraying water on leaves increased injury to ferns growth because of excess evaporation from the leaves. Though these studies, we learn that ferns are susceptible to water condition such as air humidity, soil water and water management. If other environmental factos are maintained with optimal conditions, water condition plays an important role in ferns growth in indoor environments.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.34 no.s02
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• pp.34-44
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• 1989

The stability of rice cultivation in Korea is largely depended on climatic conditions, especially, low temperature at the period of early growth stage and after heading. The improvement of cold tolerant varieties and appropriate cultural practices in rice are very effective to minimize the cold damage. This paper is summarized the mechanism and counterplans of cold injury of rice plants. The paddy area having commonly cold injury in Korea is approximately 15, 522ha in 1,709 sites on the national scale. The cold damage at seedling stage in nursery bed appeared to poor germination, leaf discoloration, dead seedlings and seedling rot ect.. At the vegetative stage, the decreased tiller number due to poor rooting and the delayed heading caused by slow growth and panicle differentiation are commonly showed. The cold injury at early reproductive stage appeared to the degeneration of spikelets and rachis - branches, while that at meiosis stage showed to increased sterility due to poor development of pollen and shortened panicle length with delaying heading, therefore the grain yield is largely decreased. The cold damage at heading and ripening stages showed to poor pollination and fertilization, low panicle exsertion, poor grain filling and finally grain quality became low. To minimize the cold injury to rice plants by low temperature, following counterplans would be recommonded ; Improvement of the cold toelrant rice varieties for the regions of midmountains and alpines. Raising healthy seedlings at upland nursery beds and by using of growth regulators such as ABA, Fuchiwang and Tachiace. Soil improvement and organic matter application to reduce cold damage by increasing water and fertilizer holding capacities in the paddy field having commonly cold water and in the place where cold damage is regularly occurred. Appropriate fertilization for raising healthy rice plants to tolerate under low temperature condition. Water management to increase water temperature in the paddy such as depth watering, round channels and polyethylene tubes around the field. Establishment of the optimum cultivation time of rice based on minimum, mean and maximum temperatures at different regions with appropriate rice varieties.

• Korean Journal of Weed Science
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• v.14 no.2
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• pp.94-100
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• 1994

This experiment was conducted to determine selective mechanism of cyhalofop-butyl ester ((((R-butyl 2-(4-(4-cyano-2-fluorophenoxy) phenoxy) propionate)) between rice and Echinochloa crus-galli. 100ppm of cyhalofop-butyl ester inhibited over 90% of seedling growth of E. crus-galli when applied at 3 leaf stage and complete inhibition was observed at 180ppm applied at the 4 leaf stage, but rice(Chucheongbyeo) was not inhibited by cyhalofop-butyl ester even at 230ppm, regardless of its growth stages(3, 4, 5 and 6 leaf stages). Cyhalofop-butyl ester applied through stem at 10 and 50ppm moved most rapidly to the meristem and resulted in the highest injury on plant height, root length and fresh weight of E. crus-galli. compared with root or leaf application. Seedlings of rice and E. crus-galli at 3 or 4 leaf stage were dipped in 180ppm of cyhalofop-butyl ester solution for 1 minute and aboveground parts of E. crus-galli and rice were removed immediataly after dipping treatment. Regrowth of E. crus-galli was inhibited by the herbicide by 41.7%, but no inhibition was observed in rice. Further, content of chlorophyll reduced to 18.7% of the untreated control, showing appearence of almost being killed, but no effect on chlorophyll content of rice was observed.

• Research in Plant Disease
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• v.14 no.1
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• pp.21-25
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• 2008

This study was conducted to decide disease incidence level of rice leaf blast required for reasonable fungicide application in paddy field. We induced the disease development by inoculating rice blast pathogens on rice seedlings (Jinmibyeo) in the greenhouse and transplanting the infected seedlings in the field two weeks after rice plants were transplanted. We scored the disease incidence, grouped and marked according to degree of percentage of diseased leaf area at maximum stage of disease development. The percent diseased leaf area (PDLA) had negative correlations with panicle number per hill, ripened grain (%), and total yield; their correlation coefficients (r), $-0.97^{**}$, $-1.00^{**}$ and $-0.96^{**}$, respectively. However, it had positive correlations with spikelets per panicle and thousand grain weight; their correlation coefficients (r), $0.98^{**}$ and $0.98^{**}$, respectively. Gain threshold (GT) calculated based on control cost and market price was estimated to be 8.35. Economic injury level (EIL) obtained based on GT and coefficient of damage of regression equation between disease incidence and the different yield components; panicle number per hill, spikelets per panical, ripened grain(%), thousand grain weight and yield were 41.8, 9.7, 19.1, 291.1 and 3.4%, respectively. Economic threshold (ET) for yield was 2.7% ($3.4%(EIL){\times}0.8$) on PDLA. These results suggest that application of fungicide is necessary when two under leaves are almost covered with lesions or contained more than twenty large lesions under leaves at maximum tillering stage.

• Korean journal of applied entomology
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• v.18 no.2 s.39
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• pp.101-106
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• 1979

Present studies were carried out to get a basic information for biological control of soybean rod borer, Grapholitha glycinivorella Matsumura, causing main injury in soybean cultivation in Korea. 1474 native strains were cultivated in field to evaluate the pod borer damage. Pubescence density and color, maturity group, seed coat color, aphid and general leaf damage and seed damage by pod borer were investigated, and determined among their relationships. As another basic study for ecological control of insect, 6 leading varieties were planted on different planting date with 3 levels of plant spacing, on which pod borer damage and some related agronomic characters were studied. The results obtained one summarized as follows: Average injury of soybean pod borer was $5.2\%$ ranging $0-38\%$ in 1474 strains planted on 20 May. Non-significant correlations were found between pod borer damage and pubescence density and color, while pod borer damage closely related with maturity groupand aphid damage at $5\%$ level ofttests. Most severe damage was found in green seed coast color and maturity group V. Late and sparse plantings tend to have more damages to the pod borer than those of early and dense plantings. Pod setting date and period of pod maturing seemed related with pod borer damage. Bongeui and Chungbuk-baik cultivars were resistance to soybean pod borer, while Clark and Kumkang-daerip were susceptible in field tests.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.42 no.4
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• pp.373-377
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• 1997

The bird repellent, methiocarb 50% WP, has been used to reduce the bird damage in the crop field in the European countries. The bird damage occaisonally would occur in the wet direct seeded rice and in soybean field, and resulted in decreasing the crop productivity by the reduction of seedling emergence rate. In this experiment, rice seeds, Hwasungbyeo(Oryza sativa), were coated with the different application rate of methiocarb, 5, 10 and 15 per kg seed, and soybean, Taegwangkong(Glycine max), 2.5, 5.0 and 7.5g. In rice, the seeds coated with 10 and 15g of methiocarb were not lost by bird, while those with 5g and control were lost to 37 and 50% of total seeds, respectively. No damage by birds was observed in rice seedling when the coleoptile and radicle of rice were emerged at 7 days after the water seeding. The crop injury of methiocarb reducing the emergence rate of seedlings, shortening the shoot length, and decreasing the leaf number was occurred at the treated of methiocarb 15g per kg seed. In soybean, the loss of the sprouting by birds was lower in the treatment of methiocarb 7.5g per kg seed than that in both the control and the treatments of methiocarb, 2.5 and 5.0g per kg seed. No crop injury by the treatment of methiocarb was observed in all application rate.

• Korean Journal of Weed Science
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• v.17 no.2
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• pp.199-206
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• 1997

Chlorsulfuron, an acetolactate-synthase-inhibiting sulfonylurea herbicide, induces many metabolic and physiological changes in susceptible plants. The objective of this study was to determine to what extent chlorsulfuton-induced phytotoxicity was due to a shortage of final products(the branched-chain amino acids valine, leucine, and isoleucine) or to an accumulation of a toxic metabolite(2-ketobutyrate), or both, in a susceptible species. Chlorsulfuron-treated canola seedlings showed growth inhibition and injury symptoms that included chlorosis, downward leaf rolling, and accumulation of anthocyanins. Supplementation with valine, leucine, and isoleucine prevented the chlorsulfuron-induced growth inhibition and injury symptoms only partially, suggesting that factor(s) other than a shortage of the branched-chain amino acids also are involved in the phytotoxicity. Canola seedlings treated with 2-ketobutyrate showed reduced growth, but they showed different changes in metabolites than seedlings treated with chlorsulfuron. The results suggest that 2-ketobutyrate is not involved in chlorsulfuron-induced phytotoxicity. We conclude that chlorsulfuron-induced phytotoxicity is due at least in part to a shortage of branched-chain amino acids.