• Korean Journal of Weed Science
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• v.30 no.2
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• pp.111-121
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• 2010

Differential tolerance to protoporphyrinogen oxidase (Protox)-inhibiting herbicides, oxyfluorfen was observed between leaf ages in squash. Physiological responses to oxyfluorfen, including leaf injury, cellular leakage, accumulation of tetrapyrroles, and antioxidative enzymes activity, were investigated in leaf age classes of squash to identify mechanisms of oxyfluorfen tolerance. Leaf 1, 2, and 3 injuries for Joongangaehobak were >10,000, 1,286, and 1.6-fold higher than that of leaf 4, after treatment of oxyfluorfen. On the other hand, leaf 1, 2, and 3 injuries for Sintowjahobak were 725, 366, and >0.6-fold higher than that of leaf 4, after treatment of oxyfluorfen. However, in contrast to oxyfluorfen treatment results, leaf injury of squash leaf 4 treated with paraquat was much smaller than in leaves 1, 2 and 3. Electrolyte leakage from the tissues treated with oxyfluorfen was higher in the youngest leaf (Leaf 4) than in the older leaves 1, 2, and 3. Differential leaf response to oxyfluorfen of squash appears to be due in large part to differences in protoporphyrin IX (Proto IX), Mg-Proto IX, and Mg-Proto IX monomethyl ester accumulation in treated leaves. In contrast, leaf 4 had higher activities of superoxide dismutase, catalase, peroxidase, ascorbate peroxidase, and glutathione reductase than leaf 1 after treatment with oxyfluorfen. However, the induction in antioxidant activity in leaf 4 was not enough to overcome the toxic effects of a Protox inhibitor, oxyfluorfen, so the leaf eventually died.

• Korean Journal of Weed Science
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• v.14 no.2
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• pp.107-111
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• 1994

Selective action of root-treated oxyfluorfen [(2-chloro-4-thrifluoromethylphenyl)-3'-ethoxy-4'-nitrophenyl ether] and chlomethoxynil [2, 4-dichlorophenyl-3'-methoxy-4'-nitrophenyl ether] were investigated. Oxyfluorfen showed greater activity to all plant species than chlomethoxynil. $^{14}C$-oxyfluorfen was little metabolized in roots of the plant species and more slowly absorbed than $^{14}C$-chlomethoxynil. These results suggest that herbicidal activity of oxyfluorfen at the site of action is higher than chlomethoxynil. In the tested plants, rice, barnyardgrass, sorghum, and corn were absorbed less of the oxyfluorfen and chlomethoxynil than the broad leaf plant species. However, no clear relationship was observed between a degree of tolerance and absorption and metabolism of both herbicides by the plant species.

• Korean Journal of Environmental Agriculture
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• v.15 no.3
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• pp.316-324
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• 1996

The four tolerant and one susceptible plant to oxyfluorfen were selected from 26 species and investigated for the inhibition of protox activity, the PPIX accumulation, and the activity of antioxidative enzymes by oxyfluorfen treatment. When treated, the oxyfluorfen-tolerant plant species showed a less decrease in fresh weight and height than the susceptible one. The susceptible barnyardgrass showed more inhibition of protox activity due to the treatment of oxyfluorfen than the tolerant species. Especially at the concentration of $10^{-6}M$, protox activity of the susceptible barnyardgrass was inhibited completely, but tolerant species maintained $25{\sim}45%$ of the activity. Under the light and dark condition, the susceptible barnyardgrass showed more PPIX accumulation than the tolerant.

• Korean Journal of Weed Science
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• v.7 no.2
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• pp.236-242
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• 1987

The study was conducted to interprete the fluctuation of weed vegetation in plant-sociological impacts as affected by the mixture use of oxyfluorfen and glyphosate with various dosages. Also, intended to know the real interaction between two herbicides in weeding efficacies. The better efficacy from the above mixture was recognized than from the oxyfluorfen + paraquat mixture on the perennial-sites. In lower rate mixture of oxyfluorfen, the dominance index was increased by the annual grass species (ie. Digitaria), and of glyphosate by the biennial Stellaria and perennial species (ie. Artemisia). Also, the positive maximum action of both oxyfluorfen and glyphosate in various mixture rates was categorized upto 0.55kg ai/ha for oxyfluorfen and 0.35kg ai/ha for glyphosate, respectively. However, the interaction between the above two herbicides recognized actually as negative. Consequently, the use of mixture compound of oxyfluorfen with glyphosate are expected rather to promote the control efficacy of specific weed species, to enlarge the weeding spectrum and to prolong the weeding periods than to reduce the application rate of both chemicals depending on any synergic interactions.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.33 no.4
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• pp.375-379
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• 1988

To identify the evidence in tolerance to oxyfluorfen between selected rice cultivars (cv. Chokoto as the tolerant and cv. Weld Pally as the susceptible), the differences in ehtylene evolution, chlorophyll contents and electro-conductivity as affected by various concentrations of oxyfluorfen were assessed. -Under 10$^{-5}$ M oxyfluorfen, the susceptible cultivar showed rapid and higher rate of ethylene evolution, and under 10$^{-4}$ M oxyfluorfen, less difference in ethylene evolution between both cultivars. -Upto 10$^{-6}$ M oxyfluorfen, no difference in chlorophyll contents of both cultivars, however, at 10$^{-5}$ ~10$^{-4}$ M, the susceptible showed as less chlorophyll contents as half of the tolerant. At 10$^{-3}$ M, both cultivars showed complete decomposition of chlorophyll. -At 10$^{-4}$ ~10$^{-3}$ M oxyfluorfen. both cultivars indicate the increased rate in electro-conductivity, and the susceptible cultivar released as much electrolytes as 10% of the tolerant.

• Korean Journal of Weed Science
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• v.16 no.1
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• pp.54-63
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• 1996

This study was conducted to investigate the anatomical and ultrastructural responses of the oxyfluorfen-tolerant and -susceptible rice cultivars with barnyardgrass, a typical susceptible weed by oxyfluorfen and the herbicides having similar mode of action treatment. After the treatment of $10^{-5}M$ oxyfluorfen, the tolerant rice cultivars no showed the structural damage of leaf surface, but the susceptible rice cultivate was damaged in the wax and the susceptible barnyardgrass was even destroyed in the tissue irregularly. Also in the susceptible rice cultivars and barnyardgrass the thickness of leaf blade was greatly decreased. The anatomical change was not observed in the tolerant rice cultivars but epidermal cells, mesophyll cells and bundle sheath cells were badly broken in the susceptible rice cultivars and barnyardgrass and especially after 24 hours of the treatment the structure of susceptible rice cultivars was completely disintegrated. The irregularity of chloroplast shape and the distortion of chloroplast envelope were generally observed and the starch tended to decrease by oxyfluorfen treatment regardless of rice cultivars. Such a structural damage were appeared more badly in the susceptible rice cultivars and bamyardgrass than in the tolerant rice cultivars. By the treatment of diphenyl ether herbicides, the thickness of leaf blade greatly reduced in the order of oxyfluorfen > acifluorfen > bifenox > oxadiazon, and the susceptible rice cultivars showed more reduction than the tolerant rice cultivars. Especially, the susceptible rice cultivars showed that the leaf structure was badly broken down with damage epidermal cells and bundle sheath cells.

• Weed & Turfgrass Science
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• v.2 no.3
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• pp.254-259
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• 2013

The mechanisms of resistance to oxyfluorfen (OF) and paraquat (PQ) were investigated in rice plants. Examination of the concentration dependence of oxyfluorfen- or paraquat-induced increase in conductivity showed that conductivities in the OF- and PQ-treated leaf squares were increased with 0.1 ${\mu}M$ oxyfluorfen and 0.01 ${\mu}M$ paraquat and further increased with higher concentrations. The levels of conductivity were approximately 10-times higher in the PQ-treated plants than in the OF-treated plants, indicating that the PQ-treated plants suffered more severe photodynamic damage than the OF-treated plants. The photooxidative stress caused by foliar application of either 50 ${\mu}M$ oxyfluorfen or 100 ${\mu}M$ paraquat increased the enzyme activities of ascorbate peroxidase and peroxidase 1 day after the herbicide treatments and then further increased their enzyme activities 2 days after the treatments. The activities of catalase began to increase 2 days after the oxyfluorfen and paraquat treatments. These antioxidant enzymes appear to play an essential part of defense mechanisms against oxyfluorfen and paraquat. Our results demonstrate that paraquat caused more severe oxidative stress, as indicated by a greater change in conductivity, thereby resulting in greater increases in antioxidant responses in plants, compared with those of oxyfluorfen.

• Korean Journal of Weed Science
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• v.4 no.1
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• pp.88-95
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• 1984

The study was intended to analyze the interaction effects of paraquat and oxytluorfen as an orchard herbicide-mixture. Data were prepared from the former report of authors. The algebraic expression for the actions of paraquat and oxyfluorfen on the control percentages of peach orchard weeds, and their interactions were determined from the multiple regression polynomial and plotted in three-dimensional graphs. As a result of treatments by combination of paraquat and oxyfluorfen on the field which was dominated by perennial weeds, the most effective interactions were detected at combination rates of $245\;gHa^{-1}$ paraquat and $470-705\;gHa^{-1}$ oxyfluorfen. However, to develope the long-term weeding-efficacies, the combination rates of paraquat are expected to raise up to $500-700\;gHa^{-1}$, and oxyfluorfen to fit at lower limits of rates, respectively.

• Korean Journal of Weed Science
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• v.16 no.4
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• pp.337-345
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• 1996

This study was conducted to investigate the protox activity, the PPIX accumulation and the activity of antioxidative enzymes of the oxyfluorfen-tolerant and -susceptible rice cultivars by oxyfluorfen and oxytluorfen-similar herbicides treatment. When treated with acifluorfen, bifenox or oxadiazon, the oxyfluorfen-tolerant rice cultivars showed less decreased in fresh weight than the susceptible rice cultivars. The inhibition of protox activity was in the order of acifluorfen > oxyfluorfen > bifenox > oxadiazon, and the PPIX accumulation was in the sequence of oxadiazon > acifluorfen > oxyfluorfen > bifenox. The inhibition of protox activity and the PPIX accumulation by the herbicide was greater in the susceptible rice cultivars than in the tolerant rice cultivars. The effect inhibiting the decrease of chlorophyll content resulting from the treatment of GC, tetrapyrrole biosynthesis inhibitor, was in the order of oxyfluorfen > acifluorfen > bifenox > oxadiazon, and the tolerant rice cultivar had more than the susceptible rice cultivar. In the treatment of DPE and oxadiazon, the activities of MDAR, POX and GR was higher in the tolerant rice cultivar than in the susceptible rice cultivar, and in the case of POX isozyme the activities of main D and E bands increased in the tolerant rice cultivars at tested herbicides but they didn't in the susceptible rice cultivar.

• 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.