• Korean Journal of Weed Science
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• v.17 no.2
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• pp.176-184
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• 1997

The rice(Oryza saliva L.) tolerance to herbicide thiobencarb was determined. At the concentration of thiobencarb 3.0kg ai/ha, Yamabiko, M73 (23)F.A, and wx 139-3-64-220-3-1 were the most tolerant among 643 rice genotypes tested. Thiobencarb reduced plant height until 14 days after treatment by 10% and 13% in tolerant and susceptible genotypes, respectively, but increased plant height in 21 days after treatment for both the genotypes, though partial stunting or dwarfing was observed during the early period until 14 days after treatment. Number of tillers per plant was greater in the plants treated by thiobencarb than in the control, showing that the tolerant genotypes had 2 to 3 tillers which were more than the susceptible ones. Regardless of the genotypes, shoot dry weight was increased by 30 to 50% in 35 days after thiobencarb treatment. The root dry weight increased by 50 to 100% in 35 days after the treatment.

• 대한공업교육학회지
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• v.34 no.2
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• pp.267-285
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• 2009

The collaborative learning has been considered as an efficient teaching model and under the recent basic learning environment, even face-to-face classroom circumstance rapidly increases the courses of blended learning which utilize the merits of e-learning environment. Nonetheless, the study on the strategy for systematic blended learning is quite scarce. In this study, the survey was done for developing the blended learning strategy, based on the collaborative learning model at the face-to-face environment and judging the satisfaction on the courses which the model was applied to. The survey consists of demographic questions, satisfaction in the whole courses, satisfaction in the collaborative learning under the blended learning environment and satisfaction in the blended learning strategy and support tools applied to each step of the learning. The result of this study is as follows. First, in response to the question that the blended learning can complement the face-to-face classroom courses, the respondents represented average 4.09 at 5-point Likert scale. And to the question whether the collaborative learning is more efficient under the blended learning environment than the face-to-face classroom, the response corresponds to 4.06 scale on the average. Second, as for the satisfaction in the blended learning strategy and support tools applied to the each step of the blended learning, the satisfaction degree is analyzed as high as over 4.0 on the average toward all the questions. Third, regarding the support tools used for the blended learning strategy, the learners consider the tools as most helpful in order of chatting, team community, mail & note and archive. Lastly, I would like to suggest that the study result should be highly reflected in constructing the collaborative learning module of learning control system in the future.

• Korean Journal of Weed Science
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• v.6 no.1
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• pp.18-24
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• 1986

This study was conducted to determine the possible role of growth regulators and the effect of foliar part cutting on the tuber formation of C. serotinus. Foliar application of 6-benzylaminopurine (BA) increased tuber number and fresh weight of C. serotinus by an average of 24.7% and 32.4%, respectively, as compared with the untreated control. However, the tuberization of C. seratinus was inhibited by single treatment of abscisic acid (ABA) and gibberellic acid (GA) as the concentrations increased. As compared with the untreated control, BA at $10^{-4}$M and combination of BA $10^{-5}$ + GA $10^{-5}$M increased 31.8% and 53.7% of tuber number, respectively, but GA at $10^{-5}$M decreased tuber number by 21.9%. 15㎏/10a of nitrogen under three levels of BA resulted in the highest number of tuber formation of C. serotinus, an increase of 24.7% as compared with the untreated control. GA treated increased flowering of C. serotinus by an average of 4.8% based on the untreated control. Tuber number and fresh weight of C. serotinus was markedly inhibited as the number of cutting times increased. Three times cutting inhibited tuber number and fresh weight of C. serotinus by 76.1% and 96.6%, respectively, under nitrogen of 15kg per 10a as compared with the untreated control.

• Korean Journal of Weed Science
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• v.5 no.2
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• pp.131-136
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• 1985

This experiment was conducted to identify the competitive ability of rice against Monochoria vaginalis Presl. and to determine effect of various herbicides on it. Photosynthetic efficiency of rice markedly increased as the density of M. vaginalis increased from 1 to 3 plants per hill. Competition index increased in propotional to an increase of M. vaginalis density while total dry matter of rice decreased in reverse. Significant yield reduction of rice, was observed at the density of M. vaginalis, 2 plants per hill and 37% at 3 plants per hill. Such a yield reduction can be mainly attributed to the decrease of panicle and spikelet number of rice which were greatly affected by competition with M. vaginalis. Regardless of herbicides tested, % inhibition increased remarkably as the concentration of herbicides increased from 1 to 20 ppm. No plant growth was observed in all the herbicides treated with 20 ppm except for butachlor, thiobencarb and bifenox, showing existence of the new promising herbicides to control M. vaginalis among the herbicides tested.

• Korean Journal of Weed Science
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• v.18 no.4
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• pp.333-340
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• 1998

The combined effects of primisulfuron and imazethapyr treated with piperonyl butoxide(PBO) on growth inhibition and acetolactate synthase(ALS) activity in corn were studied to identify the tolerance mechanism among corn cultivars. Pioneer 3751 IR showed resistance to primisulfuron and imazethapyr, but Pioneer 3751 and Chalok 2 were susceptible to them. Pioneer 3751 IR was tolerant to primisulfuron regardless of PBO treatment, but Pioneer 3751, Suwon 118 and Chalok 2 were more greatly inhibited by combined treatment of primisulfuron with PBO. Synergistic effect on growth inhibition in Pioneer 3751 IR, Pioneer 3751, Suwon 118 and Chalok 2 was not occurred when imazethapyr was treated with PBO, but Pioneer 3751, Suwon 118 and Chalok 2 tended to inhibit by combined treatment of imazethapyr with PBO. Pioneer 3751 IR showed higher ALS activity than Pioneer 3751 when primisulfuron or imazethapyr was treated. ALS activity was inhibited by primisulfuron at $0.01{\mu}M$ or above and imazethapyr at $1{\mu}M$ or above, and inhibitory effect on ALS activity was observed by primisufuron and imazethapyr treatments with PBO.

• Korean Journal of Weed Science
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• v.18 no.4
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• pp.325-332
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• 1998

This study was carried out to investigate the adsorption and the movement of herbicide fenoxaprop-P-ethyl in the silty clay soil(SiC) and the sandy loam soil(SL). Fifteen percent of the added herbicide was adsorbed within 30 min after shaking, and a quasi-equilibrium was reached after 8 to 14 h. The time required for 50% adsorption was 15.8 h in the SiC and 19.3 h in the SL. The equilibrium adsorption isotherm was followed by the Freundlich equation and the Kd was 3.86 in the SiC and 2.32 in the SL. The herbicide in the soil columns flooded with 3 cm water depth and eluted at 0.8 cm/day was leached to 6 cm and 8 cm depth at 7 and 21 days after the treatment, respectively. However, the movement was widened with increased amount of leaching water. The herbicide in the field soils was moved up to 6 cm and 8 cm depth at 14 and 56 days after the treatment, respectively. However, the large amount of the applied herbicide was distributed in 0~2 cm profile in all of the soils examined. Half-life of the chemical in soils was shorter than 7 days and the time to 90% degradation was about 4 weeks. The results indicate that the herbicide has relatively small mobility and short persistence.

• Korean Journal of Weed Science
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• v.13 no.4
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• pp.234-249
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• 1993

Herbicide is an essential agricultural chemical in the modern agriculture. Due to its bioactivity, however, risk of herbicide use against non-target organisms should be seriously considered. Among the unfavorable aspects given by herbicide, the residue is the most important because herbicide residue in soil and agricultural product is closely related to human safety. The residue in soil and crop is dependent on conditions of soil, weather, herbicide use and crop cultivation, etc. In general, the residue in soil or agricultural product in Korea is known to be not serious at this moment, except for some problems like carry-over effect on succeeding crops. To secure safety of herbicide use for the health, soil ecology and other environment, researches on herbicide residue including monitoring survey should be done more frequently and extensively. Safety guide for herbicide usage should be kept by farmers and development of long toxic herbicide should be accelerated.

• Korean Journal of Weed Science
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• v.17 no.1
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• pp.59-65
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• 1997

Bentazon 6-hydroxylase (B6H) and cinnamic acid 4-hydroxylase (CA4H) activities were determined in rice (Oryza sativa L.) microsomes to study methods of enhancing cytochrome P-450 mediated aryl hydroxylation of bentazon by hydoxylase inducing compounds. Pretreating rice seeds with 1,8-naphthalic anhydride at 0.5-2% and fenclorim at 5 and 10 ${\mu}M$ increased B6H and CA4H activities. Treatments of rice seedling with ethanol 2.5% enhanced B6H and CA4H activities, and with phenobarbital at 12 mM enhanced B6H activity, and CA4H activity was enhanced at 2 mM. B6H activity was synergistically enhanced by combined treatments of ethanol 2.5 or 5% and phenobarbital 8 or 12mM and also that of 1,8-naphthalic anhydride 0.5 or 1% and phenobarbital 8 or 12 mM, but CA4H activity was decreased by combined treatment. Five-day-old rice seedlings showed higher B6H and CA4H activities which decreased with seedling age.

• Korean Journal of Weed Science
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• v.17 no.1
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• pp.10-23
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• 1997

This study was carried out to determine distribution and tuberization characteristics of tubers of water chestnut(Eleocharis Kuroguwai Ohwi) which is a dominant weed species and diffult to control during 1993 to 1994. By early planting of E. kuroguwai tubers, more and heavier tubers were developed, but the tubers were tended to distribute at the upper soils. Large proportion of tubers was remained at the upper 0 to 10cm soil layer and a few tubers were formed below 20cm. Tubers developed earlier tended to be at deeper layer, while later developed tubers were at upper layers. Tuber weight was increased from the surface to 20cm soil depths, but that formed below 20cm was almost same. No tillage resulted in more tuber formation which were distributed at upper soil layers when compared to conventional tillage. Cool water irrigation pumped from ground water resulted in less tuberization but smaller tubers when compared to control. Shading with color cellophan films resulted in smaller tuber formation with lower in sprouting percentage. Among the films tested, the most significant effect was obtained with green color.

• Weed & Turfgrass Science
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• v.6 no.1
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• pp.40-54
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• 2017

The mound grave of Korean traditional funeral culture is a unique habitat which is a Zoysiagrass lawn being sustainable in proper management. We phytosociologically described an unusual Zoysiagrass vegetation with Gueldenstaedtia verna by the Zürich-Montpellier School's method and analyzed eco-floristic characteristics. A new association, Gueldenstaedtio-Zoysietum japonicae ass. nov. hoc loco, was identified and subdivided into festucetosum ovinae, typicum, and trifolietosum repensae. The subassociations were distinguished by the difference in species composition resulting from site accessibility and lawn management method. The association was assigned as not only a regional but also a locally-limited vegetation type, which distributes on a particular microhabitat with strong continentality in the Daegu regional subdistrict of Bioclimatological division. The Zoysiagrass vegetation of Korea was considered as a continental type apparently different from the oceanic type of Zoysion japonicae (Miscanthetea sinensis, Caricetalia nervatae). Mound graves in Korea should be acknowledged as a meaningful habitat for the in-situ conservation of biodiversity and phytocoenosen, despite being a secondary grassland of Gueldenstaedtio-Zoysietum japonicae.