Study on actinomycetic ecology in soil with the different cultivating years of ginseng

【Objective】The study was to find out ecological difference of the actinomyces among different years in Ginseng soil in Taoshan and Shichang in the southern of Xiao Hinggan Ling,Tieli city,Heilongjiang Province,and screen antagonistic actinomycetes,in order to offer a foundation for biocontrol against soil-borne disease.【Method】The quantity of actinomycetes was determined via dilution and plating.Dual culture and agar piece method was used to screen antagonistic actinomycetes and measure the inhibition.【Result】①The total actinomycetes and Stremptomyces were 106×105 CFU/g and 193×105 CFU/g of 5years,41×105 CFU/g and 83×105 CFU/g of 7years respectively,there existed very significant difference(P0.01);The numbers of Micromonospra and unidentified actinomyces were 11×105 CFU/g and 20×105 CFU/g,54×105 CFU/g and 90×105 CFU/g,significant difference respectively(P0.05).The numbers of total actinomyces,Stremptomyces,and micomonospra showed an increasing trend with the increase of planting time in Shichang site.The trend of total actinomycetes separated from Gause'No.1 medium in Taoshan was similar with that in Shichang.But the number of Stremptomyces and Micromonospra separated from Gause's No.1 medium as well as the total actinomycetes and Stremptomyces sparated from humic acid agar showed a decreasing trend with the increase of planting time.②Among 271 strains selected from tested soil,108 strains had antagonistic action to target pathogenic fungi of soil-borne diseases,40% being isolated Actinomycetes.In Taoshan,the antagonistic actinomycetes against 5 targets screened from the soil of 1 year were 2.2-12 times higher than that of 5 year in Taoshan,indicating antagonistic actinomycetes decreased along with the planting years.③Quantity and ratio of broad-spectrum antagonistic actinomycetes were as that.Flavus were the major genus among Streptomyces,15with strong activity,accounting for 4%.④The percentage of antimicrobal actinomycetes to total actinomycetes had no relation with their soil nutrients,but pH had.【Conclusion】Along with cultivating years,the soil-borne diseases aggravation was related with the quantity change of actinomycetes,especially the reduction of antagonistic actinomycetes.