| As an important commodity grain base in our country,the rice-growing areas in Northeast China have witnessed a continuous growth of paddy-planting area and the rapid growth of machine-transplanting rice cultivation.The succession of weed communities in paddy fields in northeast China was more serious due to the complicated planting and cultivation techniques such as machine transplanting,shallow tillage and the successive use of chemical herbicides..The damage of weedy weeds in rice fields such as Echinochloa oryzioides and Scirpus juncoides are aggravating day by day,and gradually become the dominant populations of weed communities in paddy-rice transplanting fields in northeast China.At present,the herbicides that can be used for controlling Echinochloa oryzioides and Scirpus juncoides are not yet clear.Therefore,the selection of the single and new mixure herbicides that is highly effective in controlling Echinochloa oryzioides and Scirpus.juncoides have important implications for the control of weeds in rice transplanting fields in Northeast China.The main research object of sensitive Echinochloa oryzioides and Scirpus juncoides populations were studied in this paper.The whole plant bioassay was used to screen out the suitable single herbicides for controlling weeds in paddy field such as Echinochloa oryzioides and Scirpus juncoides.On the basis of this,the new herbicide formulations were screened to control weeds in Northeast rice plantations and the toxicity of the new compound to other weeds in paddy fields was determined.The results are as follows:The whole plant bioassay was used to study the sensitivity of the sensitive Echinochloa oryzioides population HSQJ from Heilongjiang Province to the herbicides used to control weeds such as barnyard grass in paddy fields or other crop fields and new herbicides.And studied the safety of other crop field her-bicides screened against different rice varieties(Japonica Sanjiang 6 and Indica Liangyou 669)and the toxicity of herbicides screened to other grass weeds in paddy fields.The results showed that among the herbicides in paddy field,the eight kinds of stem and leaf treatment agents such as penoxsulam,pyribenzoxim,metamifop,flucetosulfuron.propanil,halauxifen-methyl,propyrisulfuron,quintr-ione,and the eight kinds of soil treatment agents such as oxyfluorfen,anilofos,prometryn,pretilachlor,triafamone,oxadiazole,pyraclonil,metazosulfuron had high inhibitory activity against Echinochloa oryzioides and were safe to rice in machine-transplanting rice fields.However,other crop herbicides screened were less safe to rice.On this basis,it was further found through the indoor toxicity test that metamifop,propanil,anilofos.oxyfluorfen,prometryn and pretilachlor had higher inhibitory activity on sensitive Leptochloa chinensis population,penoxsulam-resistant Echinochloa crusgalli and Echinochloa oryzioides.Through the whole plant bioassay,we studied the sensitivity of the sensitive Scirpus juncoides population HJHN collected from Heilongjiang Province to the herbicides used to control broadleaf and sedge weeds in paddy fields or other crop fields and new herbicides.And studied the safety of other selected crop field herbicides against different rice varieties(Japonica Sanjiang 6 and Indica Liangyou 669)and the toxicity of herbicides screened to other broadleaf and sedge weeds in paddy fields.The results showed that the two kinds of stem and leaf treatment agents such as MCPA-Na,bentazone and the three kinds of soil treatment agents such as metazosulfuron,prometryn,pyraclonil had high inhibitory activity against Scirpus juncoides and were safe to rice in machine-transplanting rice fields.But the other crop field herbicides screened had less safety to rice.According to the indoor toxicity test,it was found that metazosulfuron,prometryn,pyraclonil and MCPA-Na had higher inhibitory activity on Cyperus difformis,Ecliptaprostrata and Ammannia baccifera.In order to effectively control weeds which were dominated by Echinochloa oryzioides and Scirpus juncoide.s in paddy-rice transplanting fields in northeast China,and at the same time improve the control effect,increase the herbicidal spectrum and reduce the cost,the two kinds of soil treatment agents such as metazosulfuron.pretilachlor and the three kinds of stem and leaf treatment agents such as penoxsulam,metamifop,MCPA-Na were selected for indoor compounding test and use of technology research based on the above screening results.According to the Gowing's method,we found that metazosulfuron·pretilachlor could achieve the better satisfactory inhibitory effect on Echinochloa oryzioides and Scirpus juncoides in the range of 1:3-6.Combined physical and chemical properties,we ultimately determined the best ratio was metazosulfuron:pretilachlor=l:5.Simulated field efficacy test showed that the combination of metazosulfuron and pretilachlor could significantly improve the control effect,expand the herbicidal spectrum and control resistant weeds.And it could have safety of rice and have a better control effect on fresh weight of the penoxsulam-resistant Echinochloa crusgalli HYYL and Echinochloa oryzioides HQGN,sensitive Leptochloa chinensis JLGY,Cyperus difformis JNXW,Eclipta prostrata JYJD-1 and Ammannia baccifera JYJD-2 when the dose was 300-360 g ai/ha with the ratio of 1:5.According to the Golby method,we found the best ratio of the mixure of penoxsulam,MCPA-Na and metamifop that could achieve a more satisfactory inhibitory effect on Echinochloa oryzioides and Scirpus juncoides was 1:15:2.Simulated field efficacy test showed that the combination of penoxsulam,MCPA-Na and metamifop could effectively reduce the dosage,expand the herbicidal spectrum and control resistant weeds.And it could have safety of rice and have a better control effect on fresh weight of the penoxsulam-resistant Echinochloa crusgalli HYYL and Echinochloa oryzioides HQGN,sensitive Leptochloa chinensis JLGY,Cyperus difformis JNXW,Eclipta prostrata JYJD-1 and Ammannia baccifera JYJD-2 except cyhalofopbutyl-resistant Leptochloa chinensis ZHYH when the dose was 360-396 g ai/ha with the ratio of 1:15:2. |
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