• KOREAN JOURNAL OF CROP SCIENCE
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• v.42 no.1
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• pp.68-78
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• 1997

Laboratory and greenhouse studies were conducted to determine differential sensitivities on absorption of $^{14}$ C-oxyfluorfen and the anatomical responses in wheat and barley to protoporphyrinogen oxidase-inhibiting herbicides [oxyfluorfen (2-chloro-1- (3-ethoxy -nitrophen-oxy)-4-(trifluoromethyl) benzene, acifluorfen(5-[2-chloro-4-(trifluoromethyl) phenoxy]-2-nitro-benzoic acid), bifenox(methyl-5-(2, 4-dichlorophenoxy)-2-nitrobenzoate) and oxadiazon(5-tert-butyl-3-(2, 4-dichloro-5-isopropoxyphenyl)-1, 3, 4-oxadiazol-2-one)]. I$_{50}$ value of the tolerant wheat cultivars to oxyfluorfen was about 10$^{-4}$ , whereas that of the susceptible barley cultivars was about 10$^{-6}$ M, showing significant difference between the two groups. When foliage were applied with acifluorfen, bifenox or oxadiazon, the oxyfluorfen-tolerant wheat showed less decreased in shoot fresh weight and chlorophyll content than the susceptible barley. Also, when soil-applied with these herbicides test plants showed similar tendency in foliar application. Electrolyte leakage from the tissue treated with these compounds was the more influenced in the barley than the wheat. Malondialdehyde(MDA) production as index of lipid peroxidation was greater in the barley than the wheat by treatment of these compounds. Therefore, the differential sensitivities of wheat and barley to protoporphyrinogen oxidaseinhibiting herbicides was showed by our greenhouse and in vitro experiment. The absorption rates of $^{14}$ C-oxyfluorfen were higher in the barley than the wheat. And this tendency was showed appararitly difference by increase of treatment durations. After the oxfluorfen and oxadiazon treatment, the tolerant wheat did not show the structural damage in leaf surface, but the susceptible barley was damaged in the leaf waxy layer. However, the acifluorfen and bifenox treatment showed no difference between wheat and barley. The anatomical changes by these compounds treatment were not observed in the tolerant wheat but epidermal cell and mesophyll cell were highly broken in the susceptible barley.

• Research in Plant Disease
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• v.18 no.1
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• pp.24-28
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• 2012

The rice diseases occurring on the transgenic rice plant carrying protox gene (CPPO06) was assessed and compared with other varieties of rice such as Dongjin, Chucheong, Ilpeum, and Onnuri in the fields located in Cheongwon of Chungbuk, Suwon of Gyeunggi, and Gwangju of Chonnam. In the field of Cheongwon, the diseases such as blast, leaf spot, sheath blight and Fusarium blight were observed. False smut were observed only in the field of Suwon, where the ratio of diseased plants was 0.28% in CPPO06 and 0.37% in Onnuri, respectively. In the field of Gwangju, leaf spot caused by Cochlioborus miyabeanus was the most severely occurring disease among rice diseases mentioned above. Fusarium blight occurred in all the 3 fields, which were more severe in CPPO06 plants treated with or without oxadiazon as the herbicide. Except for Fusarium blight, there was no significant difference in the rice diseases as blast, leaf spot, sheath blight and false smut between CPPO06 and other rice varieties.

• Korean Journal of Weed Science
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• v.16 no.4
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• pp.327-336
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• 1996

This study was conducted to investigate the content of antioxidant and GST activity of the oxyfluorfen-tolerant and -susceptible rice cultivars with barnyardgrass, a typical susceptible weed in accordance by oxyfluorfen treatment. The content of vitamin C was higher in the tolerant rice cultivar than in the susceptible rice cultivar and barnyardgrass. The contents of vitamin E, carotenoid, glutathione(GSH, GSSG, total glutathione) were not different between the tolerant and susceptible plants. In the case of the content of vitamin C due to the treatment of oxyfluorfen, the tolerant rice cultivars, Hawon and Baru decreased less than the susceptible rice cultivars and barnyardgrass. After the treatment of oxyfluorfen the contents of vitamin E and GSH in the tolerant rice cultivars were higher than in the susceptible rice cultivars or barnyardgrass. But in the content of carotenoid was greater in the tolerant rice cultivars than in the susceptible rice cultivars but they didn`t have any difference in comparison with the susceptible barnyardgrass. And there was no difference in the content of GSSG between the tolerant and susceptible plants. When CDNB or oxyfluorfen were used as substrate, the GST activity, was higher in the tolerant rice cultivars than in the susceptible rice cultivars or batnyardgrass. After the treatment of oxyfluorfen the GST activity was not induced in the rice, but was induced in the barnyardgrass. Even after the treatment of acifluorfen, bifenox and oxadiazon the GST activity was not induced in the rice cultivars.

• Korean Journal of Weed Science
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• v.12 no.3
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• pp.271-291
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• 1992

This study was conducted to survey the situation of direct rice seeding in Honam province in Korea to investigate problems and seek countermeasure of weed control in direct rice seeding. The total area of direct rice seeding in the south-western part of Korea (Chonbuk, Chonnam, and Chungnam) was 1650.8ha (732.1ha for direct seeding in dry field and 918.7ha for direct seeding in flooding field) in 1992. The followings are summary of the study. 1. In case of direct rice seeding in dry field, butachlor EC and G at 3 to 5 DAS was mostly selected by farmers to control weeds in dry field. Benthiocarb or chlornitrofen was also used in few cases. At 10 to 14 DAS just before rice emergence, tank misture of butachlor EC and paraquat was treated by some farmers. At 35 to 40 days, after flooding mixture of sulfonylurea derivatives was sequentially applied. Surviving weeds including barnyardgrass were finally controlled by mixture of bentazon+quinclorac WP foliage application. 2. In case of direct rice seeding in flooding field, weed control were mostly unsuccessful partially due to wrong selection of herbicide and missing the optimum application time. Three relatively successful weed control in the survey were summarized as follows. 1) Oxadiazon EC, butachlor or benthiocarb were treated just after puddling(5 to 7 days before seeding). then mixture of bentazone+quinclorac WP or sulfonylurea derivatives was sequently applied to control remaining weeds at 20 days after seeding. 2) Mixtures of bensulfuronmethyl+dimepiperate G, pyrazosulfuronethyl+molinate G, or bensulfuronmethyl+mefenacet+dymron G were applied at 11 days after puddling when barnyardgrass were at 2.0 leaf stage. Phytotoxicity was not found in case of mixture of bensulfuronmethyl+dimepiperate G but found in the other two cases but disappeared later. 3) Mixtures of bensulfuronmethyl+quinclorac G., pyrazosulfuronethyl+quinclorac G or betazone and quinclorac G were treated after 18 to 20 days after puddling when barnyardgrass was within 3.0 leaf stage. It showed good weed control in both annuals and perrenials without phytotoxicity. On the contrary, other sulfonylurea derivatives such as middle periodic herbicide showed poor weed control against barnyardgrass, so that sequential treatment of bentazone+quinclorac WP mixture was required. 3. Herbicidal characteristics and optimum application time of 45 rigistered herbicides in Korea were analyzed to discover new substitute for quinclorac mixture, that showed excellent weed control against barnyardgrass at its 3 leaf stage or older. The analysis revealed that 70% of herbicides were for preemergence and the others were post periodic herbicide. Most farmers favor to apply herbicide when rice seedlings completely rooted, at this time barnyardgrass are at 2.5-3.0 leaf stage. Therefore herbicide of which optimum application time had long is required. In this study. 6 middle periodic herbicides among sulfonylurea derivatives and 2 quinclorac mixture were selected and evaluated their weeding spectrums at different leaf stage of barnyardgrass in both soil application in flooding condition and foliage application in dry paddy field. The order of weeding spectrum in magnitude was as follows : bentazone+quinclorac WP> bentazone + quinclorac G>bensulfuronmethyl + quinclorac G>pyrazosulfuronethyl + quinclorac G> pyrazosulfuronethyl + Molinate G>bensulfuronmethyl + mefenacet + dymron G>bensulfuronmethyl + mefenacet G>bensulfuron methyl+benthiocarb G. The above results coincided with that of the survey. In conclusion, there is no proper substitute for quinclorac mixrure, which can control barnyardgrass at 3.0 leaf stage or even older. Therefore quinclorac should be supplied continuously to farmers in order to anchor direct rice seeding in Korea. Author suggested the followings to eastablish direct rice seeding technology effectively and quickly : 1) A tentatively named "The research committee for direct rice seeding" which was composed of farmers. researchers and goberment. should be eastablished to cooperate effectively. 2) Development of a pricise direct rice seeding machine for both dry and flooding paddy field. which is workable regardless of condition and varieties of seeds. 3) Study on protecting rice seed and seedling from sparrows. 4) Systematic studies of weed control techniques in direct rice seeding to standardize herbicide application. 5) Studies on farm-land reformation. techniques of precise land preparation. and direct rice seeding using an airplane.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.42 no.1
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• pp.79-88
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• 1997

This experiment was conducted to investigate the protoporphyrin Ⅸ (PPIX)accumulation, activity of antioxidative enzymes and contents of antioxidant in tolerant-wheat and susceptible-barley to protoporphyrinogen oxidase (Protox) inhibiting-herbicides [oxyfluorfen(2-chloro-l-(3-ethoxy-nitrophenoxy-4-(trifluoromethyl) benzene, acifluorfen (5-[2-chloro-4-(trifl-uoromethyl) phenoxy]-2-nitrobenzoic acid), bifenox(methyl-5-(2, 4-dichlorophenoxy) 2-nitroben-zoate), and oxadiazon (5-tert-butyl-3-(2,4-dichloro-5-isopropoxyphenyl)-1,3,4-oxadiazol-2-one)]. The tolerant-wheat and susceptible-barley were soaked in these compounds at 10$^{-6}$ M for 2hrs and exposed to light for 2,4,6 or 8hrs to investigate change of the activity of antioxidative enzymes. The activities of monodehydroascorbate reductase(MDAR), catalase(CAL) and superoxide dismutase(SOD) were lower in the barley than in the wheat after the treatement of these compounds. The activity of peroxidase(POX) was lower in the barley than in the wheat at 8hrs after the treatment of oxyfluorfen but other compounds showed no difference in activity in wheat and barley. The activity of glutathione reductase(GR) was increased in wheat and barley according as hours of treatment of these compounds became increased but its activity was no difference between wheat and barley. In the case of the content of vitamin C due to the treatment of these compounds, the wheat decreased less than the barley. After the treatment of oxyfluorfen the content of vitamin E in the wheat was higher than in the barley but other compounds didn't have any difference between wheat and barley. And after the treatment of acifluorfen the content of carotenoid was greater in the wheat than in the barley but other compounds didn't have any difference between wheat and barley. The content of glutathione (GSH, GSSG) was greater in the barley than in the wheat. The content of protoporphyrin Ⅸ (PPIX) accumulation by the treatments of these compounds was more in the barley than in the wheat. Especially, the treatment of oxyfluorfen and acifluorfen were more accumulated 2.3 and 1.3 fold in the barley than in the wheat, respectively.

• Korean Journal of Weed Science
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• v.4 no.1
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• pp.11-18
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• 1984

The effect of transplanting method of rice seedlings on weed occurrence was investigated at the Yeongnam Crop Experiment Station in 1983. Rice was transplanted by hand and machine and eleven common herbicides were applied. The greatest weeds were harvested from the plot that rice was not transplanted and more weeds encountered at machine transplanted plot than hand transplanted plot. The degree of weed suppression by rice plant itself was 50% for machine transplatning and 55% for hand transplanting, respectively. Simpson index and community dominance of weed species were the highest in hand transplanting and followed by machine transplanting and no rice plot in order. Rice grain yield was exponentially correlated with the amounts of weed occurrence and more yield loss exhibited at machine transplanting than hand transplanting in the same amount of weeds. In the herbicidal activity, most of herbicides performed better at hand transplanting than machine transplanting while the degree of difference between transplanting methods varied depend on herbicide used.

• The Korean Journal of Pesticide Science
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• v.8 no.2
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• pp.79-87
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• 2004

3-Chloro-2-[4-chloro-2-fluoro-5-(5-methyl-3-phenyl-4,5-dihydroisoxazol-5-ylmethoxy)-phenyl]-4,5,6,7-tetrahy dro-2H-indazole(EK-5439) demonstrated rice selectivity and herbicidal activity on annual weeds, such as Echinochloa oryzicola, Monochoria vaginalis, Lindernia pyxidaria, Rotala indica, Aneilema keisak, Cyperus difformis, and Ludwigia prostrata at doses of 16-63 g a.i./ha. However, the application window was limited from pre-emergence to 5 days after transplanting. The control efficacy of EK-5439 on barnyardgrass was 4 times higher than that of oxadiazon. EK-5439 was excellently safe to the 16 different transplanted rice cultivars treated 2 days after transplanting. These compounds have the mechanism of action on the chlorophyll biosynthesis like protoporphyrinogen IX oxidase inhibitors.

• Korean Journal of Weed Science
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• v.15 no.3
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• pp.232-237
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• 1995

Effect of azimsulfuron {1-(4,6-dimethoxypyrimidin-2-yl)-3-[1-methyl-4-(2-methyl-2H-tetrazol-5-yl) pyrazol-5-ylsulfonl]urea} combined with eight annual herbicides on shoot and root growth of rice (Oryza sativa L.) and barnyardgrass [Echinochloa crus-galli (L.) P. Beauv.] was investigated. Annual herbicides used were four thiocarbamates (dimepiperate, molinate, esprocarb, and thiobencarb), two acetanilides (butachlor and pretilachlor), one urea (dymron), and one oxadiazole (oxadiazon) herbicide. Growth inhibition in rice shoot was greater with azimsulfuron mixed with the annual herbicides than with azimsulfuron only. The azimsulfuron mixtures did not bring about decrease in growth inhibition of rice shoot. However, safening effect in root growth of rice was obtained when dimepiperate, molinate and dymron were combined with greater than 10ppm of azimsulfuron. Greater inhibition in shoot and root growth of rice occurred with straight chain hydrocarbon substitute such as esprocarb and thiobencarb than with cyclohydrocarbon substitute such as dimepiperate and molinate. Application of the azimsulfuron mixtures resulted in increase. in growth inhibition of shoot and root growth of barnyardgrass as compared with when azimsulfuron only was applied.

• Korean Journal of Weed Science
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• v.30 no.3
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• pp.291-299
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• 2010

Cyhalofop-butyl and penoxsulam, known for respective acetyl CoA carboxylase (ACCase) and acetolactate synthase (ALS) inhibitor, have been widely using as a post-emergence foliar application for many years in wet-seeded rice field in Korea. Since 2009, control of Echinochloa oryzoides with cyhalofop-butyl and penoxsulam was no longer satisfactory. Greenhouse and experiment in rice field were conducted to confirm E. oryzoides resistance to ACCase and ALS inhibitors and to compare herbicide treatments for control of the resistant E. oryzoides to ACCase and ALS inhibitors. Three resistant E. oryzoides to ACCase and ALS inhibitors accessions were tested for levels of resistance to cyhalofop-butyl and penoxsulam, base on survival rate. Iksan and Kimje accessions were not any affected to the survival by treatment with recommended doses of two herbicides tested. Buan accession displayed an intermediate response of 62 and 72% survival at recommended doses of cyhalofop-butyl and penoxsulam, respectively. Survival rates to herbicides mixed with ACCase and ALS inhibitors at 3.5 leaf stage of E. oryzoides was over 80%. Benzobicyclon+fentrazamide+bensulfuron SC, benzobicyclon+mefenacet+bensulfuron SC, benzobicyclone +cafenstrole+pyrazosulfuron-ethyl GR controlled effectively by 2 leaf stage of resistant E. oryzoides to ACCase and ALS inhibitors. In the field experiment, single treatment of benzobicyclon+ fentrazamide+bensulfuron SC and benzobicyclon+mefenacet+bensulfuron SC failed to control E. oryzoides, but squential treatment of benzobicyclon+thiobencarb SE and benzobicyclon+ mefenacet+ bensulfuron SC controlled effectively it in rice infant seedling culture with machine. Our results suggest that resistant E. oryzoides to ACCase and ALS inhibitors had not developed multiple resistance to herbicides with different modes of action. In particular, cafenstrole, fentrazamide, mefenacet were effective control measures.