Influence Of Different Seed Coatings On Soybean Rhizospheric Bacteria Diversity And Bacteria Antagonistic To Root Rot Pathogens

Soybean root rot pathogens were isolated by conventional methods and the test screened of antagonistic bacteria and actinomyces to root rot pathogens from the soybean rhizosphere,then the antagonistic bacteria and actinomyces were identified by phospholipid fatty acid method and 16S rDNA sequencing.This experiment studied the genetic diversity of bacterial community in soybean rhizosphere and the dynamic of biocontrol bacterials against soybean root rot pathogens with DGGE,combining with dilution method after treatment with different concentrations of Metalaxyl, Carbofuran-Carbendazim-Thiram,Ningnanmycin and Fludioxonil.We gained the changes and differences of the amount of genetic diversity and biocontrol bacterial,and analyzed strength and persistent of the influence of seed coatings on the genetic diversity of bacterial and biocontrol bacterials in soybean rhizosphere,and tried to provide the reference for the research of other function microorganism.The main conclusions of this paper were as follows:1.25%of the total isolates belonged to antagonistic bacteria and actinomyces,and antibacterial effect of bacteria were better than that of actinomyces.From the identification,we could see the main bacterial strains were Bacillus subtilis and Pseudomonas spp..The main actinomyces were Streptomyces spp..2.The four kinds of seed coatings all influenced on the genetic diversity of bacterial in soybean rhizosphere.At the early period,the four kinds of seed coatings inhibited the diversity of bacterial in soybean rhizosphere except of Low-concentration of Metalaxyl,and inhibition of middle-concentration and high-concentration of Metalaxyl is smaller.At the middle of the experiment,different kinds of seed coatings had different effects on the diversity of soybean rhizospheric bacterials,the influence strength of the three concentrations of Carbofuran-Carbendazim-Thiram is smaller,closing to the normal level,at least the influence strength of two concentrations of the other seed coatings were similar.At the later period,the effects of Ningnanmycin recovered to the normal level,the influence of Fludioxonil is smaller than the others until recovered to the normal level. 3 At the 22nd day,all the treatments inhibited propagation of Uncultured Pseudomonas sp., then all the treatments promoted for propagation of it slightly,and recovered to the normal level at last.The four kinds of seed coatings influenced on Bacillus sp.very little,but at the early period, Metalaxyl promoted for propagation of Bacillus sp..4.The effect of middle-concentration of Carbofuran-Carbendazim-Thiram and Metalaxyl sustained on the 75th day.The effect of middle-concentration of Ningnanmycin sustained on the 61th day.The heredities of soybean rhizospheric bacteria were similar after treatment with Fludioxonil on the 68th day and the 75th day,the effect of Fludioxonil was stable and smaller at last until unchanged on the 82th day.