• 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.

• Applied Biological Chemistry
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• v.47 no.3
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• pp.351-356
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• 2004

Holographic quantitative structure activity relationships (HQSAR) as 2D QSAR between the herbicidal activities against root and shoot of rice plant (Orysa sativa L.) and barnyardgrass (Echinochloa crus-galli), and structures of A=3,4,5,6-tetra-hydrophthalimino, B = 3-chloro-4,5,6,7-tetrahydro-2H-indazolyl and C = 3,4-dimethylmaleimino substituents in 1-(5-methyl-3-phenylisoxazolin-5-yl)methoxy-2-chloro-4-fluorobenzene derivatives were studied and discussed. The statistical results of four HQSAR models for the herbicidal activities against root and shoot of the two plants showed the best predictability of the herbicidal activities based on the cross-validated $r^2\;_{cv}\;(q^2=\;0.760{\sim}0.924)$, non cross-validated conventional coefficient $(r^2\;_{ncv}\;=\;0.868{\sim}0.970)$ and PRESS values $(0.123{\sim}0.261)$. The results indicated that the qualities of HQSAR models for barnyardgrass were slightly higher than that of rice plant. And also, the predictability of HQSAR models were higher $(q^2\;=\;HQSAR\;>\;CoMFA)$ than CoMFA but the conventional coefficients of HQSAR models lower $(r^2\;=\;HQSAR\;<\;CoMFA)$ than CoMFA. Moreover, from the contribution maps, it was founded that the selectivity between the two plants depends upon the 2-fluoro-4-chloro-5-alkoxyanilino and $R_3$ substituent on the C-phenyl ring. These features suggest where to modify a molecular structure in order to improve its selective of herbicidal activities against barnyardgrass.

• The Korean Journal of Pesticide Science
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• v.5 no.3
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• pp.54-57
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• 2001

A series of bicyclic 4,5,6,7-tetrahydroindazole derivatives 6 have been synthesized, and their herbicidal activities were studied in flooded paddy condition. The compounds 6 showed herbicidal effects to barnyardgrass and Monochoria and good tolerance against rice at a rate of $0.063kg/ha{\sim}0.25kg/ha$.

• The Korean Journal of Pesticide Science
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• v.4 no.2
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• pp.72-75
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• 2000

3,4-Dimethyl-N-[4-chloro-2-fluoro-5-{(pyrazolylmethyl)oxy}phenyl]maleimides or 3,4,5,6-tetrahydro-N-[4-chloro-2-fluoro-5-{(pylazolylmethyl)oxy} phenyl]phthalimides were prepared and evaluated their herbicidal activities under paddy conditions. Those compounds which have N-methyl-5-pyrazolylmethyloxy moiety showed good tolerance in transplanted rice and strong herbicidal activities on barnyardgrass below 60 g/ha of dose.

• 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.

• The Korean Journal of Pesticide Science
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• v.4 no.3
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• pp.15-18
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• 2000

A series of N-{2,4-dichloro-5-(3-pyrazolyl)Phenyl}imides 7 and 8 was prepared and evaluated their herbicidal activities. Those compounds in which either carboxylate or carboxamide moiety is on pyrazole moiety 7c-71 showed no herbicidal activity whereas, the compounds in which trifluoromethyl group is substituted in pyrazolyl moiety showed moderate herbicidal activities against barnyardgrass, monochria and flat-sedge under paddy conditions with good rice tolerance at rate 63-250 g/ha.

• The Korean Journal of Pesticide Science
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• v.5 no.4
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• pp.68-71
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• 2001

Of the cyclic imide type compounds, S-275 was known to exhibit a potent herbicidal effects. We have designed and synthesized the compounds having diverse subsutuents in place of the chlorine group of bicyclic 4,5,6,7-tetrahydroindazole part of S-275. Their herbicidal activities were studied under flooded paddy conditions. The results showed that the most compounds gave relatively weak herbicidal activities, whereas tile compound substituted with methylthio group showed potent herbicidal effects against paddy weeds at a rate of 0.015 kg/ha and improved tolerance on rice compared to S-275.

• The Korean Journal of Pesticide Science
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• v.7 no.4
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• pp.310-313
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• 2003

New series of 9-(5-Isoxazolemethoxyphenyl)imino-8-thia-l,6-diazabicyclo[4.3.0]nonan-7-one which are the cyclic imide type compounds were designed and synthesized. The herbicidal activities of main dominant weeds to these compounds were evaluated under rice field condition. There is the possibility for a new herbicide since the most of compounds were excellent to main dominant weeds occurring in rice field without the serious rice injury.

• 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.

• The Korean Journal of Pesticide Science
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• v.4 no.1
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• pp.11-18
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• 2000

This study was conducted to establish an efficient screening method of membrane-disrupting herbicides, based on the result that membrane leakage leading to evolution of carbonyl compounds and aldehydes could be colorimetrically assessed by formation of stable chromophores with MBTH and ferric chloride. Assay conditions including plant material, light intensity, irradiation time, concentrations of reagents for colorization, and reaction time were optimized, and activities of different types of known herbicides were investigated with cucumber cotyledon discs. That result indicated that this assay was sensitive to membrane-disrupting herbicides, such as protoporphyrinogen oxidase inhibitors (acifluorfen, oxyfluorfen, oxadiazon) and an electron interceptor from photosystem I(paraquat). With seven compounds newly synthesized, highly positive correlation was observed between herbicidal activities measured by greenhouse bioassay and MBTH method. Because only a single disc(4 mm diameter) from cucumber cotyledon in 60 ${\mu}L$ of incubation solution was required to assay, a large number of herbicides could be tested simultaneously using 96-well microtitre plates. But the assay efficiency is not likely to significantly increase because of the boiling step during the reaction.