Study On Resistance Mechanism Of Amaranthus Retroflexus L To Fomesafen Of Soybean Field

Heilongjiang,as a major agricultural province in China,is the home of soybeans in China.It has vast arable land area and per capita occupation.Among them,only the planting area of soybean in Nenjiang County has reached 2.84 million mu.Amaranthus retroflexus L.,one of broadleaf weeds in soybean fields in Heilongjiang Province,has been listed as a malignant weed in many parts of the world.In Heilongjiang Province,the main weed control method in soybean fields is chemical control.Diphenyl ether herbicides have been widely used because of their good weeding effect,wide weed control spectrum and high selectivity.Fomesafen is one of the most common post-emergence foliar treatments in soybean fields.In recent years,the extensive use of fomesafen in soybean fields in Heilongjiang Province has resulted in varying degrees of resistance of Amaranthus retroflexus in some areas,it is difficult to control Amaranthus retroflexus effectively within field dose,and herbicide resistance has been enhanced with the increased duration of its use.In order to further elucidate the resistance of Amaranthus retroflexus to fomesafen and provide theoretical basis for the research and control of resistant weeds,the resistant population(R)of Amaranthus retroflexus in soybean field of Dongsheng Village,Qianjin Town,Nenjiang County,Heihe City,Heilongjiang Province and the non-resistant sensitive population(S)of Amaranthus retroflexus in Patriotic Village,Suiyang Town,Dongning County,Mudanjiang City were studied i n this study.The biological characteristics,resistance mechanism,effects of leaf age on resistance and cross-resistance and multi-resistance of diphenyl ether herbicides of population(S)were studied.The main experimental results are as follows:(1)The biological characteristics of resistance and susceptible Amaranthus retroflex populations1)Compared with the susceptible population(S),the resistant population(R)had larger fresh weight,seed yield and mass per plant,and there was no significant difference in plant height.It was observed under electron microscope that the seed size was larger,the seed coat was thinner and the surface was smoother.2)Germinative force and germination index of R population were 71.5%,65.0% and 30.1%,respectively.And those of S population were 59.3%,43.1% and 43.1%,respectively.3)After treatment with 200g/L gibberellin and 20°C/35°C,the germination rate of the resistant population(R)was higher than that of the susceptible population(S).4)The S population was more easily to dormant than the R population because of low temperature.5)With the increase of sowing depth,the emergence rate of Amaranthus retroflexus increased first and then decreased.The emergence rate was the highest in 2cm.During the whole process of depth variation,the average emergence rate of R population was always higher than that of S population.(2)Study on the resistance mechanism of Amaranthus retroflexus to fomesafen1)Through transmission and scanning electron microscope,after 7 days of application,the palisade tissue,chloroplast,mitochondria,stomatal structure and quantity of R population and S population were damaged in varying degrees,but the damage degree of R populat ion was less than that of S population.2)Studies on P450 inhibitors such as prochloraz,piperonyl bromide and malathion showed that the combination of the fomesafen increased the sensitivity of the Amaranthus retroflexus resistant population(R)to fomesafen.Among them,malathion and fomesafen were the most effective treatments.The enhanced activity of P450 s may be one of the mechanisms by which the anti-branched resistance population(R)is resistant to fomesafen.3)In the non-treated control group,the GSTs activity of different Amaranthus retroflexus populations fluctuated with the change of time after treatment,and the S population changed greatly.The activity value of R population was higher than that of the sensitive population at the whole stage,which was 1.76 times.In the treatment group,the GSTs activity values of different populations showed a trend of decreasing first,then increasing and finally decreasing with the increase of the time after treatment.The R population began to rise 1 day later,and the S population began to rise 3 days later.The activity value of R population was higher than that of S population during the whole experiment stage.After 14 days,the recovery degree of activity in R population is greater.4)In the control group,the PPO activity values of different Amaranthus retroflexus populations fluctuated with the change of the treatment time.With the increase of the application time,the PPO activity values of different Amaranthus retroflexus populations in the treatment group decreased first,then increased and finally decreased After treatment for 1 day,the activity of R population began to increase,and the activity of S population began to increase after 3 days of treatment.Throughout the experiment stage,the activity of R population was higher than that of S population.And the recovery degree of the activity in R population was greater on the 14 th day after application.(3)The resistance in different leaf ageThe herbicidal activity of fomesafen on different leaf ages of different Amaranthus retroflex populations was different,and there was a correlation between leaf age and the rate of the plant height and fresh weight inhibition,photosynthesis,stomatal conductance and chlorophyll content of different leaf age.The greater the age of the Amaranthus retroflex,the smaller the index is affected,and the easier it is to recover.It was difficult to recover to the level of non-application after the treatment of 3-leaf-age population.Compared with the S population,the R population of the same leaf age had no obvious inhibition effect.,and the above indexes could be recovered quickly to the level of non-application.(4)Cross-resistance and multi-resistance of Amaranthus retroflexus to diphenyl ether herbicides.1)Resistant populations of Amaranthus retroflexus(R)showed cross-resistance to four diphenyl ether herbicides,namely,Fomesafen,Acifluorfen sodium,Lactofen and Fluoroglycofen-ehyl2)The resistant population of Amaranthus retroflexus(R)developed resistance to imidazolium nicotinic acid,chlorosulfasalazine,thiophenesulfuron and zosulfasalazine,which were four ALS inhibitors,as well as clomazone and dimethasone.No resistance to glyphosate,glyphosate,nitrosulfonate,atrazine and 2,4-dibutyl ester.