The Community Structure Of Weeds In Tobacco Fields In Chongqing And Chemical Control Technique

Tobacco is an important cash crops, and occupies a very important position in China’s national economy.Weeds compete with tobacco for light, water, nutrients and space, intermediate host as many pests and diseases, affect the yield and quality of tobacco. In the means of weed control, chemical weedding because of its efficiency, labor, effort, and other characteristics, is an important means of controlling weeds in tobacco fields. China’s tobacco fields herbicides varieties are less,and mostly soil treatment agent. The soil treating agent can control weed in early growth of tobacco,but in the late growth of tobacco,the leaf herbicides is more effective.The tobacoo leaf herbicides is only Rimsulfuron.In this study, base on the investigation of Chongqing tobacco fields weed community structure and soil seed bank, in combination with other broadleaf crop chemical control of weeds,Screen the eight herbicide through the field efficacy trials, the results show that the sulfometuron is safe for tobacco and effective for weed control. Digitaria sanguinalis (L.) Scop.and Eclipta prostrata (L.) L. as the test material, determine several additives synergies of sulfometuron and the best mix concentration through laboratory bioassays. At last, we verify the additives reduction and synergies of sulfometuron through the field efficacy trials. The results are as follows:1、Survey of weeds community structure research in tobacco fields in ChongqingUsing the inverted "W" the nine sampling method,survey the weed community structure of major tobacco planting counties in Chongqing. The results show that there are121species of weeds which belong to35families in tobacco fields in Chongqing, The Chenopodiumn album L.、Perilla frutescens (L.) Britt、Polygonum nepalense Meisn、Digitaria sanguinalis (L.) Scop.、Setaira viridis (L.) Beauv、Galinsoga parviflora Cav.、Artemisia princeps Levl. Et Vant、Artemisia annua L. are dvantages for the Chongqing region in tobacco fields of weeds. Chongqing southeast advantage weeds are、henopodium album L.、Perilla frutescens (L.) Britt.、Artemisia annua L.、 Setaira viridis (L.) Beauv. and Mazus japonicus (Thunb.) O. Kuntze.; Chongqing northeast advantage weeds are:Artemisia princeps Levl、Digitaria sanguinalis (L.) Scop.、Setaira viridis (L.) Beauv.、Echinochloa crusgali (Linn.) Beauv. var. zelayensis (H.B.K.) Hitchc.、Perilla frutescens (L.) Britt.and Chenopodium album L.; Chongqing in central advantage weeds are:Digitaria sanguinalis (L.)、Polygonum nepalense Meisn.、Galinsoga parviflora Cav.、Artemisia annua L.、Acalypha australis Linn.and Polygonum persicaria L. 2、The quantitative characteristics of soil weeds seed bank in tobacco fields in ChongqingSurveyed the soil weeds seed bank composition and quantity of Chongqing City, in Youyang, Qianjiang, Pengshui, Fengjie and Wushan five tobacco planting counties.The results show that:Weed seed bank in the soil a total of33species which belong to16families, mainly distributed at the0-10cm soil layer, is Digitaria sanguinalis (L.) Scop. accounting for26.65%of the total weeds. is the advantage weed species and a special focus on the object. In the five planting tobacco counties, the Wushan, Youyang, Qianjiang tobacco fields of soil weed seedbank number is larger, the weed seeds density are respectively48050grains/m2,44933grains/m2,35000grains/m2; the Pengshui, Fengjie tobacco fields of soil weed seedbank number is smaller, the weed seeds density are respectively25933grains/m2、28125grains/m2.3、Screening of the tobacco fields leaf postemergence herbicidesScreen the Fluazifop-P, Haloxyfop-P, Quizalofop-P, Clethodim, Fomesafen, Acifluorfene, Trifloxysulfuron sodium,. Rimsulfuron eight herbicides through field efficacy trials. The results show that:Spraying after30days, the best25%sulfone ethyl water dispersible granules strains of weed control effect and fresh weight, respectively,70.68%,70.21%, and tobacco relatively high security. The best strains of weed control effect and fresh weight are Rimsulfuron, respectively,70.68%,70.21%, and tobacco relatively high security.4.. The Rimsulfuron synergistic formulation researchThe Digitaria sanguinalis (L.) Scop., Eclipta prostrata (L.) L.and Nicotiana tobacum as the test material, determine the Azone, Beichuang, and Silwet408three additives the Rimsulfuron synergies through laboratory bioassays. The results show that:The Beichuang has best synergistic effect of Rimsulfuron,and when the concentration of0.02%(V/V), the synergistic effect is best, controlling Digitaria sanguinalis (L.) Scop., Eclipta prostrata (L.) Inefficiency coefficients are1.24,1.30.5n Beichuang to Rimsulfuron synergiesDetermine the Beichuang to Rimsulfuron reduction synergies through field efficacy trials. The results show that:Reduce Rimsulfuron amount of20%～30%and add0.02%(V/V) Beichuang, the strains control effect are85.18%,84.89%, and compared to the recommended dose87.56%is no significant difference; the fresh weight,control effect are88.06%、85.77%and compared to the recommended dose is85.89%no significant difference; show that reduce Reduce Rimsulfuron amount of20% ～30%and add0.02%(V/V) Beichuang without affecting the control effect.