Studies On The Safety Of Clodinafop Propargyl Emulsifiable Concentrate On Wheat Cultivars

The aryloxyphenoxypropionate (AOPP) class herbicide clodinafop propargyl, in the form of a concentrate-emulsion, which is a postemergence herbicide commonly used to control gramineous weeds in wheat field. But it caused yellow-green or yellow interveinal chlorosis on some wheat varieties. In order to study the causes of the phytotoxicity, the sensitivity difference of12wheat cultivars to this herbicide by method of Petri dish、pot and field experiment were studied. In this paper, it was also to determine differences in antioxidative activites on the tolerance of wheat cultivars Ningmai16(sensitivity) and Huaimai23(tolerance) to clodinafop propargyl.The sensitivities of12samples to clodinafop propargyl were assayed by method of Petri dish respectively. The results showed that the root of Ningmai16and the bud of Ningmai14were the most sensitive to this herbicide, the IC50(the half maximal inhibitory concentration) was0.1386mg(a.i.)/L and1.7210mg(a.i.)/L, the root of Huaimai28、Huaimai23、Xumai27and the bud of Huaimai23were the most insensitive, the IC50was0.7071mg(a.i.)/L-0.9818mg(a.i.)/L and343.5000mg(a.i.)/L respectiviely, the root was more sensitive to clodinafop propargyl than the bud. The sensitivities of12samples to the herbicides with foliage application were determined in greenhouse. The results showed that the phytotoxicity index of Ningmai wheat cultivars were higher than the others, the symptoms were yellow interveinal chlorosis appeared early and accelerated aging, the damaged area was large white heart leaves, the plants became a little shorter, growed weakly, lodging easily, the higher the concentration was, the higher the index. However, the phytotoxicity index of Huamai wheat cultivars were lower than that of Ningmai, chlorosis level of injury was little. Hydroponics assay results indicated that the growth rate of the overground parts of Ningmai16was the lowest among the12samples at15days after treatment with clodinafop propargyl, it was decreased76.88%-77.07%, Ningmai13(48.86%-71.88%) and Yangmai15(54.85%-66.85%) came second; root growth rate of Yangmai 15was decreased96.31%-97.18%significantly, Huaimai25(83.59%-81.00%) and Xumai27(89.84%-93.21%) took second place; the root top ratio of Ningmai13was decreased16.17%-18.88%significantly, Huaimai23and Huaimai26take second place, while the root top ratio of Ningmai16and Zhenmai5was increased21.37%-25.55%and3.10%-4.55%respectiviely. In conclusion, Ningmai16、Ningmai13were the most sensitive cultivar; Zhenmai5、Zhenmai168、 Yangmai15、Ningmai14were the moderate sensitive cultivar; Huaimai23、Xumai27、Huaimai26、Huaimai28、Huaimai0703、Huaimai25were the tolerance cultivar.In the experiment of the different sowing ways, the phytotoxicity index of the treamtment with sowing uncovered soil was higher than the treatment with sowing covered soil significantly; it was increased2.65times in wheat cultivar Ningmai16(sensitivity) and2.09times in Huaimai23(tolerance). The wheat resistance was reduced and the damage level was exacerbated by sowing uncovered soil. Compared with appling80g/L clodinafop propargyl emulsifiable concentrate alone, the damage index of Ningmai16was reduced significantly mixed with7.5%pyroxsulam WG、3%mesoslfuron-methyl OF were decreased75.52%、68.29%and it was increased13times treatiing with fenocaprop-p-ethyl mixture in Huaimai23. The damage index of Ningmai16treated with4%gibberellic acid emulsifiable concentrate was decreased36.13%after using80g/L clodinafop propargyl emulsifiable concentrate. It was decreased55.54%coordinately appling0.1%riacontanol microemulsion in Huaimai23. The phytotoxicity index of wheat cultivar Ningmai16and Huaimai23treated with120mg/L and240mg/L concentration of clodinafop propargyl (activity ingredient) were decreased36.55%-59.84%、8.81%-42.41%and13.47%-36.73%、21.81%-51.30%respectiviely by adding different proportion of cloquintocet-mexyl, a safener. The safety was the best as the proportion of clodinafop propargyl and cloquintocet-mexyl was8:3, the index was decreased42.42%-59.84%(in Ningmai16) and34.02%-58.30%(in Huaimai23) significantly.The content of malondialdehyde (MDA)、chlorophyll、soluble sugar, GSH, activity of SOD、 POD、GSTs were measured respectively in seedling of Ningmai16cultivar (sensitivity) and Huaimai23(tolerance) treated with80g/L clodinafop propargyl emulsifiable concentrate in pot experiment. The results showed that MDA content was increased56.41%in the leaf of Ningmai16and chlorophyll content was decreased68.58%at15days after treatment with120mg/L concentration of clodinafop propargyl (activity ingredient), SOD and POD activity was increased 130.75%and123.06%, GSH content and GSTs acticity was increased32.58%and23.33%respectiviely. Under the same treatment, Chlorophyll、MDA、soluble sugar content and GSTs acticity were changed invisibly in Huaimai23, the SOD、POD activity and GSH content were increased225.96%、63.87%and46.57%respectiviely. However, GSTs activity was increased41.11%in Huaimai23at240mg/L concentration higher than that of Ningmai16. Thereby, the tolerance wheat cultivar could enhance its antioxidant abilities to reduce the damage of herbicide stress. So there were significant differences in antioxidative activites on the tolerance of wheat cultivars to clodinafop propargyl.