• Korean Journal of Environmental Agriculture
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• v.25 no.3
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• pp.268-275
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• 2006

ALA (5-aminolevulinic acid) has been proposed as a tetrapyrrole-dependent photodynamic herbicide by the action of the protoporphyrinogen IX oxidase (Protox IX). A study was conducted to determine photodynamic herbicidal effect of ALA on seedling growth of rice (Oryza sativa L.) and barnyard grass (Echinochloa crus-galli Beauv. var. oryzicola Ohwi) under dry and wet conditions. ALA effect on early plant growth of rice and barnyardgrass was greatly concentration dependant, suggesting that it promotes plant growth at very low concentration and inhibits at high concentration. No significant difference in herbicidal activity of biologically and synthetically produced ALAs on plant lengths of test plants was observed ALA exhibited significant photodynamic activity regardless of PSDIP and its duration. Significant shoot growth inhibition by ALA soaking treatment exhibited apparently, indicating that ALA absorbed through root system was translocated into shoot part of plants. ALA reduced plant heights of rice and barnyardgrass seedlings by 6% and 27%, respectively, showing more tolerant to ALA in rice under wet condition. Leaf thickness was reduced markedly by ALA with increasing of ALA concentration, due to mainly membrane destruction and severe loss of turgidity in mesophyll cells, although the epidermal was little affected. It was observed that photodynamic herbicidal activity of ALA applied by pre-and post-emergence application exhibited differently on plant species, and that the activity of ALA against susceptible plants was highly correlated with growing condition.

• 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.

• 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.

• Applied Biological Chemistry
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• v.51 no.3
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• pp.219-222
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• 2008

In the search for third generation herbicidal cyclic imide derivatives, the average values of herbicidal activity ($pI_{50}$) in vivo (pre-emergence) of 40 new peroxidizing herbicides, 1-(4-chloro-2-fluoro-5-propargyloxyphenyl)thiourea derivatives (1-40) against rice plant (Orysa sativa) and barnyard grass (Echinochlor crus-galli) were studied. The molecular similarity between protoporphyrinogen IX (protogen) as the substrate of protox enzyme and Urea derivatives (1-40) was discussed quantitatively. The diallyl (20) and 3-nitro substituent (33) showed the selective herbicidal activity against barnyard grass. Allyl substituent (8) and their molecular similarity in dice (S=0.81) showed the highest levels of herbicidal activity ($pI_{50}$=4.71). Also, similarity indices (S) and superimposed volume (C) of protogen and aryl-substituents (21-40) showed good correlation.

• Journal of Food Hygiene and Safety
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• v.38 no.3
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• pp.79-88
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• 2023

Trifludimoxazin is a triazinone herbicide that inhibits the synthesis of protoporphyrinogen oxidase (PPO). The lack of PPO damages the cell membranes, leading to plant cell death. An official analytical method for the safety management of trifludimoxazin is necessary because it is a newly registered herbicide in Korea. Therefore, this study aimed to develop a residual analysis method to detect trifludimoxazin in five representative agricultural products. The EN method was established as the final extraction method by comparing the recovery test and matrix effect with those of the QuEChERS method. Various sorbent agents were used to establish the clean-up method, and no differences were observed among them. MgSO₄ and PSA were selected as the final clean-up conditions. We used LC-MS/MS considering the selectivity and sensitivity of the target pesticide and analyzed the samples in the MRM mode. The recovery test results using the established analysis method and inter-laboratory validation showed a valid range of 73.5-100.7%, with a relative standard deviation and coefficient of variation less than 12.6% and 14.5%, respectively. Therefore, the presence of trifludimoxazin can be analyzed using a modified QuEChERS method, which is widely available in Korea to ensure the safety of residual insecticides.