• Korean Journal of Weed Science
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• 제15권3호
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• pp.214-223
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• 1995

Tolerant corn cultivars to bentazon were selected and tolerance mechanism of corn cultivars to bentazon was studied by determining bentazon 6-hydroxylase(B6H) activity which was known to detoxify bentazon to 6-hydroxy bentazon at induced enzyme conditions with treatments of 1,8-naphthalic anhydride, ethanol and phenobarbital. Tolerant cultivars to bentazon were selected by growth response of corn by foliar application of bentazon to corn cultivars. Kwanganok, GA 209, IK 2, DB 544, and Suwon 19 were tolerant to bentazon, but KSS 3, KSS 4, KS 5, and Danok 2 were susceptible. Pretreating corn seeds with 1,8-naphthalic anhydride increased B6H activity at all cultivars, but the tendencies were more remarkable at Suwon 19 and GA 209, tolerant cultivars, than at Danok 2 and KS 5, susceptible cultivars. Treating corn shoots with ethanol increased B6H activity at Suwon 19 and GA 209. B6H activity was enhanced by treatments of ethanol at 1.0 or 2.5%, but decreased at ethanol 2.5 or 5.0% at Danok 2 and KS 5. Treating corn shoots with phenobarbital increased B6H activity at Suwon 19, GA 209, Danok 2, and KS 5 by treatments of phenobarbital at 2.0mM, but decreased at 4.0 or 8.0mM at all cultivars. Therefore, the tolerant mechanism of corn cultivars to bentazon may be explained partially by the activity of bentazon 6-hydroxylase which detoxifies bentazon to 6-hydroxy bentazon.

• Korean Journal of Environmental Agriculture
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• 제7권1호
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• pp.1-7
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• 1988

In order to clarify how much of the residues of Bentazon could be taken up by crops, soybean and radish were grown for 28 days in soils containing freshly treated $^{14}C-Bentazon$ and non-extractable soil-hound residues of $^{14}C-Bentazon.$ The results obtained are summarized as follows. 1. $^{14}CO_2$ evolution from $^{14}C$-Bentazon during the 6-month pre-incubation in soil was 14.79% relative to the applied radioactivity. 2. Mineralization of ^$^{14}C$-Bentazon in soil to $^{14}CO_2$ during 28 days of crop growing was much higher in the freshly treated soil than in the bound soil, and much higher in radish than in soybean. 3. The amounts of $^{14}C-Bentazon$ and its metabolites absorbed by soybean and radish were 45.41 and 21.48%, respectively, in freshly treated soil, whereas those were 3.92 and 1.23% in bound soil, respectively. The translocation ratios of radioactivity .from the root to the shoot were much higher in radish than in soybean, remarkably. 4. The uptake ratios of the freshly treated $^{14}C-Bentazon$ to the bound $^{14}C-Bentazon$ by soybean and radish were 12 : 1 and 17 : 1, respectively. 5. It was well verified that the presence of crops enhanced the mineralization to $^{14}CO_2$ and the transformation to polar metabolites of Bentazon.

• Korean Journal of Environmental Agriculture
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• 제12권2호
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• pp.121-128
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• 1993

In order to elucidate the degradation of the herbicide bentazon (3-isopropyl-2,1,3-benzothiadiazin-4-one-2,2-dioxide) by soil microorganisms, it was incubated at $23{\pm}1^{\circ}C$ under the submerged and upland soil conditions of the different soils in the Chung Buk area. When bentazon (200 ppm) was incubated in Cheong Won A soil (silty loam; pH, 5.2; organic matter 1.4%) under the submerged condition for 6 months, 6-hydroxy bentazon (1.27%) was formed as the major degradation product and 8-hydroxy bentazon (0.57%) and anthranilic acid (0.13%) were formed as the minor ones. Meanwhile, when 500 ppm of bentazon was incubated in the same soil for 2 months, a trace amount of 6-hydroxy bentazon was formed. Eight strains of microorganisms isolated from the soils did not give any distinct degradation products in the pure culture experiment. The greater dehydrogenase activity in Cheong Won A soil than in Cheong Ju A soil might be related to the greater bentazon-degradability of the former soil than that of the latter. When bentazon (10 ppm) was incubated for 14 days with 14 strains of bacteria and 8 strains of fungi, the identities of which were all known, Rhizopus stolonifer produced 4.6${\sim}$31.6% of anthranilic acid as the major product from batch to batch, with trace amounts of 6-hydroxy bentazon and 8-hydroxy bentazon as minor products. The rest microorganisms did not produce any noticeable products.

• Korean Journal of Environmental Agriculture
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• 제16권3호
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• pp.207-211
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• 1997

Laboratory experiments were conducted to the potential ability of bioremediation with bentazon such as determining the absorption, translocation, and metabolism of $^{14}C-Bentazon$ in minari after foliar applications. The absorption and translocation of $^{14}C-bentazon$ were compared when applied to foliar of minari. In foliar applications, 21% was observed in treated leaves, 66% remained in water extracts of leaf surfaces, and 13% was found in the epicuticular wax layer after 2d. Translocation of the herbicide from treated leaves to roots was very low(79 to 9%). Analysis of methanol-soluble extracts of $^{14}C$ indicated that more than 60% of the foliarapplied herbicide was metabolized in all plant sections after 2d. However, 77% or more of the bentazon was degraded in roots and shoots 2d after root absorption. The major metabolite in these experiments was an unknown compound that was less polar than bentazon and 6- and 8-hydroxy bentazon.

• Toxicological Research
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• 제17권2호
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• pp.123-129
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• 2001

This study were carried out to investigate cytotoxicity of paraquat and bentazon that is scattering to farm products were essensial for human diet and compensatory effects of 3-methylcholanthrene (3-MC) in vitro and in vivo. In vitro, The 5.0$\times$$10^4$ cell/ml of NIH 3T3 fibroblast in each well of 24 multidish were cultured. After 24 hours, the cells were treated with solution of paraquat and bentazon (1, 25, 50, 100 pM respectively). After the NIH 3T3 fibroblast of all groups were cultured in same condition for 48 hours, Sulfohordamin B Protein (SRB) assay were performed to evaluate the cytotoxicity of cell organelles. Paraquat and bentazon $SRB_50$ were 1860.73 $\mu\textrm{M}$, 1913.38 $\mu$M respectively. In vivo, Sprague Dawley male rats divided into paraquat and bentazon only administered group and simultaneous application group of paraquat and bentazon and 3-MC. At 30 min. and 1, 3, 6, 12, 24, 48 and 96 hrs. interval after each treatment, the animals were sacrificed by decapitation and kidney were immediately removed, immersed in fixatives, and processed with routine method for light microscopic study. Paraffin sections were stained with H-E, PAM, and PAS. Under the light microscope, atrophic change of renal corpuscles were frequently observed from 3 hrs after paraquat and bentazon treatment. The increase of the mesangium was apparent from 12 hrs later after paraquat and bentazon treatment. Necrotic changes of the epithelium and loss of brush border of proximal tubules were most severe at 48 hrs after paraquat and bentazon treatment, respectively. In contrast there were no evidences of the toxic effects on renal tissues at 48hrs in paraquat and bentazon plus 3-MC treated groups.

• Korean Journal of Weed Science
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• 제17권4호
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• pp.400-406
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• 1997

Greenhouse studies were conducted to evaluate the tolerance of 42 pepper cultivars to postemergence applications of bentazon [3-(1-methylethyl)-(1H)-2,1,3-benzothiadiazin-4(3H)-one 2,2-dioxide]. Cultivars, Jopoong, Singsing House, Sweet Green, Kwangbok, and Ilcheon showed relatively tolerant response to bentazon, while cultivars, Dahhong, Early Glory, Korea, Cheongyang, Nostalgia, and Daejanggyeong were susceptible ones to it. At rates over 2.40 kg ai/ha, the tolerant cultivars appeared to be clearly or more tolerant than the susceptible cultivars. For the determination of growth inhibition by bentazon, the concentration required to reduce growth by 50% (GR_(50)) was 2.00 to 2.40 kg ai/ha for susceptible cultivars, and 10.00 to 12.00 kg ai/ha for tolerant cultivars. Moreover, the herbicide rate required to inhibit growth by 50% $(I_{50})$ was 2.40 kg ai/ha for susceptible cultivars and 9.60 kg ai/ha for tolerant cultivars, respectively. On the $I_{50}$ and $GR_{50}$ estimates of growth, the tolerant cultivars were 5- to 6-fold more tolerant to bentazon than susceptible ones.

• Korean Journal of Weed Science
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• 제18권2호
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• pp.161-170
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• 1998

Antagonistic mode of action of fenoxaprop-P-ethyl [ethyl(R)2-4-{(6-chloro-2-benzoxazolyloxy) phenoxy}propionate] with bentazon was investigated with respect to absorption, translocation, metabolism, and change in target site response of fenoxaprop-P-ethyl using four-leaf stage of rice(Oryza sativa L.) and barnyardgrass [Echinochloa eras-galli (L.) P. Beauv.]. Shoots of rice and barnyardgrass was more sensitive to fenoxaprop-P-ethyl than the roots. More than 90% of fenoxaprop-P-ethyl was absorbed within 6 hours after treatment and 30% of the absorbed was acropetally and basipetally translocated at 24 hours after treatment. Fenoxaprop-P-ethyl was rapidly transformed to its acid form, fenoxaprop(2-[4-(6-chloro-2-benzoxazolyloxy)phenoxy]propionic acid), which was subsequently metabolized to polar conjugates. However, changes in absorption, translocation, and metabolism of fenoxaprop-P-ethyl by bentazon treatment were not found in both species. Background activity of acetyl-CoA carboxylase(ACCase) in rice and barnyardgrass was 26.5 and 23.2nmol/min/mg, respectively. Concentration required to inhibit fifty percent enzyme activity$(I_{50})$ in vitro was 6.5~7.4${\mu}M$ of fenoxaprop-P-ethyl and more than 500${\mu}M$ of bentazon. There were no significant differences in $I_{50}$ value between two treatments of fenoxaprop-P-ethyl alone and its bentazon mixture. However, bentazon reduced ACCase activity in vivo and inhibited electron transport in chloroplast thylakoid. Based on the results obtained, it is concluded that the antagonistic effect of bentazon occurs due not to direct effect on target site of fenoxaprop-P-ethyl, but to indirect involvement in reducing herbicidal activity of fenoxaprop-P-ethyl through physiological disturbances caused by bentazone at whole chloroplast level.

• Korean Journal of Soil Science and Fertilizer
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• 제45권6호
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• pp.936-942
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• 2012

This review was to elucidate the fate of Bentazon(3-isopropyl-1H-2,1,3-benzothiadiazin-4(3H)-one-2,2-dioxide) and its metabolites in soil. Bentazon is rapidly degraded to form polar metabolites which are mostly adsorbed to soil components, such as humin or fulvic acid, as non extractable forms and mineralized into $CO_2$ by light or micro-organisms in both aerobic or nonaerobic condition. The degradation of Bentazon is dependent on the rate of organic matters in soil and the use of land for the tillage. The degradation rate is decreased as the amount of organic matters in soil increases and if the land is under use for tillage. Sorption and mobility of Bentazon depends on soil pH and the content of organic matters in soil. Usually, the sorption of the metabolites of Bentazon is decreased with increase in the mobility and pH. Almost all of Bentazon is degraded within rhizosphere or forms conjugate bonds with soil organic matters before it reaches to the ground water.

• Korean Journal of Environmental Agriculture
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• 제28권3호
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• pp.274-280
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• 2009

In order to elucidate the adsorption mechanism of the herbicide, bentazon and its metabolites on soil, their adsorption patterns on soil and six adsorbents were investigated with Freundlich, Langmuir and linear isotherm. Freundlich constants ($K_f$) and maximum adsorption amount($Q^0$) of bentazon on soil was 0.55 and 3.97. Kd and Koc values of it were 0.18 and 18. The all of metabolites used except deisopropylbentazon amounts sorbed on the soil were much higher than bentazon. The most of 8-hydroxybentazon was adsorbed on soil showing $K_f$ = 316.6, $Q^0$ = 3,488, Kd = 29.7 and Koc = 2,970. Bentazon, deisopropylbentazon and 8-hydroxybentazon were shown high affinity to anion exchange regardless of pH and $NH_2$ in low pH range. Reversed phase $C_{18}$ resulted in 100% retention of N-methylbentazon regardless of pH and other metabolites were retained below 40%. The AIBA was strongly adsorbed in silica gel, COOH and cation exchange phase but poor retention was on anion exchange sorbent. 2-Aminobenzoic acid showed an amphipathic nature which had high affinity for COOH and cation exchange phase at pH 7.0 as well as $NH_2$ and anion exchange sorbent at pH 3.0.

• Korean Journal of Weed Science
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• 제18권1호
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• pp.28-35
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• 1998

Cyhalofop/bentazon ME and pyribenzoxim EC herbicides were originally developed as foliarapplied herbicides to control weeds at 4-5 leaf stages of barnyard grass 20-25 days after seeding (DAS) in direct-seeding culture but further possible utilization of these two herbicides earlier than 3-4 leaf stages of rice were evaluated for a field where early weed infestations might be severe. The application of cyhalofop/bentazon ME and pyribenzoxim EC at right after rice emergence and the 2-3 leaf stages of rice had an excellent weed control efficacy with above 90% up to 30 DAS without a phytotoxicity of rice plant and the control efficacy of over 80% was maintained until 60 DAS. However, these two herbicides controlled Echinochloa crus-galli very effectively above 97% but Aneilema keisak and Aeschynomene indica were not controlled by cyhalofop/bentazon ME and Cyperus serotinus by pyribenzoxim EC. Therefore, to control those problem weeds, second systematic application of pyribenzoxim EC and pyrazosulfuron/mefenacet G for A. keisak and A. indica, and pyrazosulfuron/molinate G, cyhalofap/ azimsulfuron/molinate G, pyrazosulfuron/mefenacet G and bentazon SL for C. serotinus at 30 DAS was found to be very efficient herbicide systems.