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Study on Resistance of American Sloughgrass (Beckmannia Syzigachne (Steud.) Fernald) Population in Wheat Field to Fenoxaprop-P-Ethyl

Author: AiPing
Tutor: DongLiYao
School: Nanjing Agricultural College
Course: Pesticides
Keywords: American sloughgrass (Beckmannia syzigachne (Steud.) Fernald) Fenoxaprop-P-ethyl Resistance Adaptability Chemical control
CLC: S451.221
Type: Master's thesis
Year: 2011
Downloads: 8
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Abstract

In this paper, the Beckmannia syzigachne Steud. Populations which were collected from wheat fields in Jiangsu province and Shanghai, were chosen as a mian research object. The susceptibility of B. syzigachne populations to fenoxaprop-p-ethyl was evaluated by both seed-bioassay and whole plant assay. Also the cross-resistance of the Jurong population to other AOPPs and CHD was determined by the same methods. And the mulitiple resistance of the Jurong population to other herbicides was measured by whole plant assay. The adatability of B. syzigachne to environment were studied by dish dipping method. Available techniques used for chemical control of B. syzigachne were studied in laboratory. Results obtained were listed as following:The susceptibility of seventeen B. syzigachne populations (collected in 2009) to fenoxaprop-p-ethyl indicated that resistance to fenoxaprop-p-ethyl had occurred in fourteen B. syzigachne populations, in which Jurong population appeared to be the most resistant population with the highest relative resistance factors of 144.24 (by seed-bioassay) or 174.42 (by whole plant assay), and B. syzigachne population collected from the Dr. Sun Yat-sen’s Mausoleum was the susceptible population in this study with the lowest ED50 value. And the susceptibility level of fifteen B. syzigachne populations (collected in 2010) to fenoxaprop-p-ethyl determined by seed- bioassay indicated that most of B. syzigachne populations were resistant to fenoxaprop-p-ethyl. And Jurong population also was the most resistant population, B. syzigachne population collected from the Dr. Sun Yat-sen’s Mausoleum also was the susceptible population.The study of the cross-resistance and mulitiple resistance revealed that Jurong population was also resistant to other AOPPs and CHD. It was concluded that the resistance level was ranked as below:quizalofop-P-ethyl>haloxyfop-R-methy> clodinafop-propargyl>clethodim, and had no mulitiple resistance to other herbicides.The study of ecological adaptability of B. syzigachne population resistant to fenoxiaprop-p-ethyl showed that no significant difference was observed in the seed germination of both the resistant and susceptible population at pH values ranged from 4 to 10. Germination rate of the resistant seeds was lower than the susceptible seeds under conditions of whole light or 10℃. The inhibitions of osmotic potential and salt stress on the germination of resistant population were higher than to the susceptible population. The resistant seeds germination was completely inhibited under the -0.5 Mpa osmotic potential, while the susceptible seeds germination rate could reach 41.9%. The resistant seeds germination was completely inhibited under 160 mM salt concentration, while the susceptible seeds germination rate was 51.7%. The inhibition of pH stress, water potential and salt-stress to the shoot and root length of resistant population was greater than to the susceptible population.In order to screen out effective herbicides that could be used to control B. syzigachne resistant to Fenoxaprop-P-ethyl in wheat fields, the suspectibility of B. syzigachne resistant population to six herbicides were evaluated by pot-spraying method. The investigation revealed that acetochlor, mesosulfuron, isoproturon and chlorotoluron could control B. syzigachne effectively. According to the principles of expanding kill-weeding table, reducing the cost and increasing effect, t were used to the screening of the optimum formulation was conducted by Gowing’s method and isoble method and two optimum formulation were obtained, which were imesosulfuron mixed with tribenuron-methyl (ratio of 1:2) and isoproturon mixed with chlorotoluron (ration of 1.5:1). The suspectibility of B. syzigachne and V. sativa to the two groups of mixtures was evaluated by pot-spraying methed, in which two groups got the general inhibition rate over 90%.

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