| In the current study, we selected glyphosate, glufosinate ammonium, hexazinone, atrazine,2,4-dichlorophenoxyacetic acid and dicambaas the herbicides, to study their herbicidalefficacy in the eucalyptusforest. The results showed that the effect of stem injection was better than foliage spraying treatment. The visual control effect of hexazinone,glyphosate,2,4-dichlorophenoxyacetic acid, dicamba, glufosinate ammonium and atrazine by stem spraying treatment at the 4 times the recommended dose was 36.67%,28.33%,6.67%, 5.50%, 3.00% and 0.00%, while the strain control effect was21.01%,6.90%,0.00%, 0.00%,2.71%and 0.00%. According to the above, the effect of the hexazinonewas better than other herbicides by stem spraying treatmentand had a longer duration.The safety of herbicidesto eucalyptusby stem spraying teratment showed that all the doses of glufosinate ammonium and 1/2 and 1 times the recommended doses of glyphosateweresafe for eucalyptus; 2,4-dichlorophenoxyacetic acid and dicamba caused the deformation of plants, serious cause the death after 28 d. Hexazinone and atrazine had obvious phytotoxicity to eucalyptus. Low dose of hexazinone and atrazine caused phytotoxicity while high dose killed the plants.We chosedhexazinone to study the initial distribution and the degradationin soil as it had the best efficacy by stem spraying treatment. In addition, we studied the absorption and conduction of the hexazinone in theeucalyptus with the high performance liquid chromatography method. The average recoveries of soil samples and plant samples were in the range of 80.85%~100.30% with the relative standard deviation in the range of 1.53%~8.19%. The precision and accuracy of the method were better and in accordance with the testing requirements for the next experiments.In order to study the initial distribution of hexazinone in soil, the method of dyeing tracer was used on the simulation application.The stain area wasconstantlyincrease from 11.3% to 84.7%in the depth of 0~5cm and reachedthe highest 89.3%in the depth of5~8cm.The stain area was constantlydecreasedfrom 8cm and reachedto 17.1cm.The distribution of herbicide was mainly in the surface layer of soil with the depth of 0~15cm.In degradation experiment, the degradative equation were respectively Ct=258.38×e-0.054 t in 0.400 g/pot and Ct = 119.92×e-0.061 t in 0.200 g/pot. The half-lifeswere 12.84, 11.36 days.Hexazinone was quickly absorbed and conducted by eucalyptus. The content of hxazinone in the roots, stems, upper leaves and lower leaveswere48.50, 33.38, 45.71 and 0 mg/kgrespectively at1 d. And at 25 d, the content of hxazinone reached 483.32, 244.63, 263.12 and 434.01 mg/kg. The results showed that there wasa correlation betwee accumulation and transportation of hexazinon.The stem spraying treatment ofhexazinone had the best efficacy to weedings and certain phytotoxicity to eucalyptus when contrasted with other fiveherbicides. Therefore, hexazinone was selected as the herbicide by stem spraying treatment for further investigations, mainly in the surface layer of soil and easily degradable in the soil, and can be quickly absorbed and conducted, therrfore leaded damage to eucalyptus. |
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