• Journal of Photoscience
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• v.8 no.2
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• pp.61-66
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• 2001

Using maize green- and white-leaf tissue, we have examined the effect of various chemicals on cytoplasmic leakage with respect to the light requirement or chloroplast targeting for their activities. Oxyfluorfen, oxadiazon, diuron, and paraquat, which are known as representative herbicides acting on plant chloroplasts, caused the electrolyte leakage only in the green tissues, whereas 2, 4-dinitrophenol, rose bengal (singlet oxygen producing chemical) and methyl-jasmoante (senscence-stimulating chemical) play a role both in green- and white-tissue. Benzoyl(a) pyrene, generating superoxide radical upon light illumination, functions only in white tissues. Tralkoxydim, metsulfuron-methyl and norflurazon showed no effect in two tested plant samples. In terms of light requirement in electrolyte leakage activity, diuron, oxyfluorfen, oxadiazon, rose bengal, and benzoyl(a) pyrene absolutely require the light for their functions, but other chemicals did not. based on these results, we could classify into four different response types according to whether chemicals require light or chlroplasts for their action. This classification is likely to be applied to simply and rapidly identify the requirement of light and chlroplasts for the actions of chemicals, thereby it makes easy to characterize many new herbicides that their action mechanisms are unclear, and to elucidate the mode of action of them.

• Weed & Turfgrass Science
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• v.5 no.4
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• pp.191-195
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• 2016

Tefuryltrione is a new hydroxyphenylpyruvate dioxygenase (HPPD) inhibitor, which has been recently registered for the use for paddy rice, Korea. Dose-response studies were conducted to compare rice safety and weed control efficacy of tefuryltrione against Eleocharis kuroguwai. When rice and E. kuroguwai were applied at a range of doses of tefuryltrione, $GR_{90}$ values (the dose required to inhibit weed growth by 90%) of E. kuroguwai were $82.38-93.39g\;a.i.\;ha^{-1}$ in two independent experiments. The $GR_{10}$ values (the dose required to inhibit rice growth by 10%) of tefuryltrione for rice were $297.77-471.54g\;a.i.\;ha^{-1}$. As a result, the selectivity indices ($GR_{10}$ for $rice/GR_{90}$ for E. kuroguwai) of tefuryltrione were 3.19-5.72. Therefore, these results demonstrate that tefuryltrione has a relatively high selectivity between rice and E. kuroguwai with a high herbicidal activity against E. kuroguwai and a good rice safety.

• Korean Journal of Weed Science
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• v.17 no.2
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• pp.169-175
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• 1997

The effect of different cultural patterns on the growth and herbicidal response of rice(Oryza sativa L.) and barnyardgrass(Echinochloa crus-galli var. oryzicola) was studied tinder direct-seeded rice and early rice seedling conditions. In dry-seeded rice condition, the growth of rice and barnyardgrass was the greatest in 3cm-seeding depth and 40% soil moisture, respectively. At 10 days after herbicide application, plant height of rice was severely inhibited in 1cm-seeding depth and 50% soil moisture, and the degree of inhibition was severer at application of pendi+molinate EC as compared to that of butachlor EC. On the other hand, plant heigth of barnyardgrass by treatment of herbicides was severely reduced regardless of seeding depth and soil moisture. The lengths of barnyardgrass mesocotyl and rice coleoptile were increased with increasing seeding depth and were severely inhibited by applied herbicides in 1cm-seeding depth under dry-seeded rice condition. The dry weight of rice at different leaching times after herbicides application showed slightly decreasing trend as the leaching time was delayed, but the growth of barnyardgrass was very severely inhibited regardless of the leaching time. In addition, the phytotoxicity of rice showed decreasing trend with the increase in transplanting depth and delay of application time under early rice seedling condition.

• Korean Journal of Weed Science
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• v.16 no.3
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• pp.187-193
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• 1996

To supply seeds with a good quality as plant materials for herbicide screening and to know whether the germination characteristics could be associated with a differential response to herbicides, germination characteristics and differential responses to herbicides were investigated with 3 species of a genus Setaria ; Yellow foxtail(Setaria glauca P. Beauv, SETGL), Giant foxtail(Setaria faberi Hetrm, SETFA), and Green foxtail(Setaria viridis P. Beauv, SETVI). Degree of dormancy was high in the order of SETGL, SETVI and SETFA. The dormancy of SETGL seed was relatively well removed by room temperature and drying storage, but SETFA and SETVI by low temperature and wetting storage(stratification). For breaking dormancy of SETGL, SETVI and SETFA, it was necessary for being kept under the above storage conditions for at least 2, 4 and 4-5 months, respectively. When the dormancy-breaked seeds were transfered to low temperature($4^{\circ}C$) and drying condition, SETGL showed germination rate of 96% even after 2 month storage. However, SETVI and SETFA showed a decreased germination of 54% and 69%, respectively, with a decreased velocity of germination, indicating that secondary dormancy might be induced. On the other hand, a significant change in germination rate was not observed as the seeds were transfered to room temperature($25^{\circ}C$) and drying condition. The germinability of SETGL seed began to decline from 6th year after storage in room temperature and drying condition. All of 3 species showed relatively high germination rate at alternating temperature of $30^{\circ}C$/$20^{\circ}C$(14hr/10hr) and their germination were not increased by light. All of 3 species exhibited similar responses to cycloxydim, sethoxydim and primisulfuron in greenhouse experiment. In contrast, SETVI and SETFA were relatively susceptible to fenoxapropethyl, SETFA to fluazifop-butyl, SETGL and SETFA to clorimuron-ethyl, and SETGL to EK-2612. The difference in herbicidal response among 3 species was the highest in the treatment of EK-2612. These results suggest that there is no a consistent tendency in responses of 3 species to herbicides which have the same target site. And the relationship between germination characteristics and differential responses to herbicides was not found.

• Korean journal of applied entomology
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• v.22 no.2 s.55
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• pp.147-159
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• 1983

In general, herbicides have been classified according to selectivity, mobility. time of application, methods of application, mode of action and chemical property and structure. However, there was no generally accepted classification system for practical use in the field. The primary processes affected by the majority of herbicides are the growth process through cell elongation and/or cell division, the photosynthetic process specifically the light reaction, the oxidative phosphorylation and the integrity of the membrane systems. The usual approach in the study of the mechanism by which herbicides kill or inhibit the growth of plants is to initially determine the morphological phototoxicity systems, The mechanism by which a herbicide kills a plant or suppresses its development is actually the resultant effect of primary and secondary(or side) effects. In most instances, the death of the plant is due to the secondary effects. To induce the desired response, a herbicide must be able to gain entry into the plants and once inside, to be transported within the plant to its site(s) of activity in concentrations great enough. Obstacles to the entry and movement of herbicides in plants are generally classified by leaf and soil obstacles, translocation obstacles and biochemical obstacles, and these obstacles are also strongly influenced by plant species and by environmental factors such as light, temperature, rainfall and relative humidity. And hence, in most instances, results obtained from laboratory or greenhous vary from those of field experiment. Author attempted to classify herbicides from the field experiment using the two-dimensional ordination analysis to obtain practical information for selecting effective herbicides or to choose effective herbicide combinations for increasing herbicidal efficacy or reducing the chemical cost. Based on this two-dimensional diagram, desired herbicides or combinations were selected and further investigated for the interaction effects whether these combinations are synergistic, additive or antagonistic. From the results, it was concluded that these new approach could possibly be give more comprehensive informations about effective use of herbicide than any other systems.

• Korean Journal of Weed Science
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• v.11 no.2
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• pp.106-110
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• 1991

There was a tendency that the growth inhibition of early growth due to herbicides was increased with increasing the amount of fertilizers. As a matter of fact, pretilachlor and pyrazolate increased the degree of injury with increasing the amount of fertilizers, and dimepiperate was actually safe regardless of the amount of fertilizer applied, while in case of bensulfuron, the injury become less when it was applied without fertilizers. As for organic matters, dimepiperate and pyrazolate were rather safe without organic matter, while pretilachlor and bensulfuron become really safe with the application of organic matter more than 1,000 kg/10a.

• Korean Journal of Weed Science
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• v.11 no.2
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• pp.100-105
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• 1991

Maintaining the water level at 5cm depth showed less decreasing in number of tiller and dry weight as compared to 1 and 3cm depths when Bensulfuron and Pretilachlor were applied. The drainage more than 5cm as water level everyday caused the growth inhibition when Bensulfuron and Pretilachlor were used, while Dimepiperate was rather safe.

• Korean Journal of Weed Science
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• v.14 no.2
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• pp.112-119
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• 1994

The experiment was conducted to investigate the cause of the continous increase of Sagittaria trifolia dominance and it's effective control methods in the paddy rice fields. Early physilogical response of S. trifolia caused by sulfonylurea three herbicides resulted in growth cessation. However, the growth-ceased plant regrew after the certain period of time. Pyrazolate{4-[2, 4-dichloro benzoyl]-1, 3-dimethylpyrazol-5-yl-ptoluene sulphonate} could control S. trifolia until 6-7 leaf stages. The herbicidal activity of S. trifolia by pyrazolate was not related to the size of tuber and the amount of carbohydrate consumption in the tuber. The production of S. trifolia tubers inhibited more than 95% by the systematic treatment of pyrazosulfuron-ethyl{Ethyl-5-(4, 6-dimethoxy pyrimidin-2-yl carbomoyl sulfamoyl)-2-chloro-2', 6'-diethyl acetanilide}, cinosulfuron and pyrazolate after the first treatment of pyrazosulfuron-ethyl and pyrazolate.

• Korean Journal of Weed Science
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• v.14 no.4
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• pp.245-251
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• 1994

The initial growth and herbicidal responses of Scirpus planiculmis were examined under both laboratory and greenhouse condition. Initial growth of S. planiculmis at two different soils(soil A and B), was compared with the growth at normal paddy soil, and growth rates at two soils were 32% and 86% as compared to the growth rates at normal paddy soil. Two different soils were soil A(rice-uncultivable) and soil B(rice-cultivable). Transplanted(2.5 leaf stage) and direct seeded rice(Dongjinbyeo) could not grow at soil A. The growth of transplanted rice at soil B was almost same as the growth at normal paddy soil, but the growth of direct seeded rice was 50% of the growth at normal paddy soil. S. planiculmis among the perennial weeds was most tolerant to NaCl, and Cyperus serotinus, Eleocharis kuroguwai, Sagittaria pygmaea, Sagittaria trifolia, Potamogeton distinctus were followed. The intial growth rate of S. planiculmis was more rapid than C. serotinus. Cutting types and times of corm reduced 20-40% of the initial growth of S. planiculmis. During the initial growth of S. planiculmis, the growth of S. planiculmis was severly inhibited by the earlier removal of corm from seedlings, and it represents that the corm plays an important role in the initial growth of this species. Bentazone among 14 commercialized herbicides showed the best safety on direct seeded rice and the highest control effect agaist S. planiculmis.

• The Korean Journal of Pesticide Science
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• v.9 no.3
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• pp.250-261
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• 2005

This study was conducted to investigate the herbicidal response and effective control strategy of sulfonylurea(SU)-resistant Scirpus juncoides Roxb. occurred in the paddy fields of Korea. A biotype of Scirpus juncoides Roxb. resistant to SU was identified in the paddy fields treated with SU herbicide-based mixtures for seven consecutive years. The apparent SU resistance observed in Scirpus juncoides Roxb. was completely confirmed in greenhouse tests. The susceptible biotype was almost controlled at the recommended dose of all the tested, but the resistant biotype was survived 20 to 30% even at 10 times higher dose of each the recommended dose of SU herbicides. The $GR_{50}$ values of 4 SU herbicides for the resistant biotype were 53 to 88 times higher than those for the susceptible biotype. The acetolactate synthase(ALS) isolated from the resistant biotype against bensulfuron-methyl and pyrazosulfuron-ethyl was less sensitive than that of the susceptible biotype. The $I_{50}$ values of the resistant biotype against bensulfuron-methyl and pyrazosulfuron-ethyl were 498 and 126 times higher than those for the susceptible biotype. A rapid diagnosis for identifying resistance of Scirpus juncoides Roxb. was possible within at least 3 days after SU herbicides. Three herbicides having different mode of action from SU herbicide, carfentrazone-ethyl, pyrazolate and simetryne exhibited excellent controlling effects on the resistant biotype of Scirpus juncoides Roxb. till 3.5 leaf stage. Among the SU-based herbicides, pyriminobac-methyl+pyrazosulfuroil-ethyl+carfentrazone-ethyl GR and azimsulfuron+carfentrazone-ethyl+pyriminobac-methyl GR were very effective to control resistant biotype of Scirpus juncoides Roxb. without rice injury. The resistant biotype which were not controlled with SU herbicise-based herbicides survived from the fields were effectively controlled by bentazone SL.