The application of a mixture of bentazone(3-isopropyl-1H-2,1,3-benzothiadiazin-4(3H)-one-2,2-dioxide)and atrazine (6-chloro-N2-ethyl-N4-isopropyl-1,3,5-triazine-2,4-diamine)is a practical approach to enhance the herbi...The application of a mixture of bentazone(3-isopropyl-1H-2,1,3-benzothiadiazin-4(3H)-one-2,2-dioxide)and atrazine (6-chloro-N2-ethyl-N4-isopropyl-1,3,5-triazine-2,4-diamine)is a practical approach to enhance the herbicidal effect.Labo- ratory incubation experiments were performed to study the degradation of bentazone and atrazine applied in combination and individually in maize rhizosphere and non-rhizosphere soils.After a lag phase,the degradation of each individual herbicide in the non-autoclaved soil could be adequately described using a first-order kinetic equation.During a 30-d in- cubation,in the autoclaved rhizosphere soil,bentazone and atrazine did not noticeably degrade,but in the non-autoclaved soil,they rapidly degraded in both non-rhizosphere and rhizosphere soils with half-lives of 19.9 and 20.2 d for bentazone and 29.1 and 25.7 d for atrazine,respectively.The rhizosphere effect significantly enhanced the degradation of atrazine, but had no significant effect on bentazone.These results indicated that biological degradation accounted for the degrada- tion of both herbicides in the soil.When compared with the degradation of the herbicide applied alone,the degradation rates of the herbicides applied in combination in the soils were lower and the lag phase increased.With the addition of a surfactant,Tween-20,a reduced lag phase of degradation was observed for both herbicides applied in combination. The degradation rate of bentazone accelerated,whereas that of atrazine remained nearly unchanged.Thus,when these two herbicides were used simultaneously,their persistence in the soil was generally prolonged,and the environmental contamination potential increased.展开更多
Combined toxicity of herbicides to non-target crops is usually resulted from their successive application.The present study was conducted to assess the combined toxicity of flufenacet（FLU）and imazaquin（IMA）to sorg...Combined toxicity of herbicides to non-target crops is usually resulted from their successive application.The present study was conducted to assess the combined toxicity of flufenacet（FLU）and imazaquin（IMA）to sorghum with their concentration in soil pore water.The concentrations that inhibited growth by 50%（IC50）of FLU and IMA individually and their combination estimated from the herbicide concentrations in soil pore water notably differed from those based on the amended concentrations,due to the decline in bioavailability resulting from adsorption of the herbicides onto soil.According to the amended concentrations,the combined effect of FLU and IMA in soil on sorghum growth was identified as additive action.Based on the concentration in soil pore water,however,it was determined to be antagonism,which was identical to that observed in a test using culture solution.The results revealed that pore water herbicide concentration might be an effective tool to assess the combined toxicity of herbicides in soil to rotational crops.展开更多
基金the Natural Science Basic Research Plan in Shaanxi Province of China(No.2004K03-G3)the Scientific Research Fund of the Department of Education of Shaanxi ProvinceChina(No.04JK234)
文摘The application of a mixture of bentazone(3-isopropyl-1H-2,1,3-benzothiadiazin-4(3H)-one-2,2-dioxide)and atrazine (6-chloro-N2-ethyl-N4-isopropyl-1,3,5-triazine-2,4-diamine)is a practical approach to enhance the herbicidal effect.Labo- ratory incubation experiments were performed to study the degradation of bentazone and atrazine applied in combination and individually in maize rhizosphere and non-rhizosphere soils.After a lag phase,the degradation of each individual herbicide in the non-autoclaved soil could be adequately described using a first-order kinetic equation.During a 30-d in- cubation,in the autoclaved rhizosphere soil,bentazone and atrazine did not noticeably degrade,but in the non-autoclaved soil,they rapidly degraded in both non-rhizosphere and rhizosphere soils with half-lives of 19.9 and 20.2 d for bentazone and 29.1 and 25.7 d for atrazine,respectively.The rhizosphere effect significantly enhanced the degradation of atrazine, but had no significant effect on bentazone.These results indicated that biological degradation accounted for the degrada- tion of both herbicides in the soil.When compared with the degradation of the herbicide applied alone,the degradation rates of the herbicides applied in combination in the soils were lower and the lag phase increased.With the addition of a surfactant,Tween-20,a reduced lag phase of degradation was observed for both herbicides applied in combination. The degradation rate of bentazone accelerated,whereas that of atrazine remained nearly unchanged.Thus,when these two herbicides were used simultaneously,their persistence in the soil was generally prolonged,and the environmental contamination potential increased.
基金supported by the National High Technology R&D Program of China(No.2013AA065202)the National Natural Science Foundation of China(Nos.41271489,21477112)+1 种基金the Zhejiang Provincial Natural Science Foundation(No.LZ13D010001)Specialized Research Fund for the Doctoral Program of Higher Education(No.20120101110073)
文摘Combined toxicity of herbicides to non-target crops is usually resulted from their successive application.The present study was conducted to assess the combined toxicity of flufenacet（FLU）and imazaquin（IMA）to sorghum with their concentration in soil pore water.The concentrations that inhibited growth by 50%（IC50）of FLU and IMA individually and their combination estimated from the herbicide concentrations in soil pore water notably differed from those based on the amended concentrations,due to the decline in bioavailability resulting from adsorption of the herbicides onto soil.According to the amended concentrations,the combined effect of FLU and IMA in soil on sorghum growth was identified as additive action.Based on the concentration in soil pore water,however,it was determined to be antagonism,which was identical to that observed in a test using culture solution.The results revealed that pore water herbicide concentration might be an effective tool to assess the combined toxicity of herbicides in soil to rotational crops.
