Detection Of Soil Microorganisms And Screening Of Antagonistic Fungi From Tobacco Filed Soil In Luoyang

In order to clear and definite the annual dynamics changes of microorganisms and the species of antagonistic fungus in tobacco filed soil of Luoyang district. The tobacco filed soil as for experiment samples which from different stages during tobacco period in Songxian County, Luoning County and Ruyang County, The soil microorganisms were isolated with the plate dilution method and the antagonistic effect of soil fungi on pathogenic fungi were screening with the confrontation culter method on PDA, The antagonistic fungus of taxonomic status was identified based on the morphological characteristics and the sequence of r DNA-ITS.(1)The number of microorganisms was bacteria>fungus> actinomycetes its maximum value is 1.31×109、3.4×105、2.7×105CFU.g-1; During the growing periods of tobacco plants, the number of bacteria and fungus both showed that to increase then decrease tend. the most count was found at the vigorous growth stages, and the number of bacteria more constant in 3 to 6 years of continuous cropping tobacco. The number of actinomycetes have different reasons in different county, different growing periods and continuous cropping years of tobacco filed soil.(2) Separated and preservatyed 178 strains of fungus, of which 136 strains belong to 15 different genus, and Penicillium, Fusarium, Aspergillus, Trichoderma were dominant population and their separation frequency of 63.83% in soil.(3) Screened 17 strains of antagonistic fungus, including 5 strains of Trichoderma, 5 strains of Penicillium, 2 strains of aspergillus and 5 strains of unknown.(4) The antagonistic Trichoderma are Trichoderma harzianum Rifai, Trichoderma tomentosum Bissett, Kubicek & Szakaes, Trichoderma asperellum Samuels, Trichoderma atroviride Karsten and Trichoderma velutinum Bissett, Kubicek & Szakaes. The Penicillium are Penicillium chrysogenum, Penicillium polonicum and Penicillium sp. The Aspergillus are Aspergillus terreus Thom.(5) Trichoderma harzianum Rifai and Trichoderma asperellum Samuels have better antagonism effect to Fusarium oxysporum Schlecht, Phytophthora parasitica var. nicotianae(Breda de Hean) Tuker and Pythium aphanidermatum(Edson) Fitzpatrick, and Trichoderma asperellum has inhibition to above three kingds of pathogenic is the first report. Trichoderma velutinum Bissett, Kubicek & Szakaes has inhibition to Fusarium oxysporum Schlecht and Phytophthora parasitica var. nicotianae(Breda de Hean) Tuker and Trichoderma tomentosum Bissett, Kubicek & Szakaes has inhibition to Phytophthora parasitica var. nicotianae(Breda de Hean) Tuker and Pythium aphanidermatum(Edson) Fitzpatrick are the first report.(6) The R3-3strain of Penicillium sp has the best antagonism effect to Fusarium oxysporum Schlecht and Pythium aphanidermatum(Edson) Fitzpatrick. Aspergillus terreus has the better antagonism effect to Phytophthora parasitica var. nicotianae(Breda de Hean) Tuker and Pythium aphanidermatum(Edson) Fitzpatrick.In this study, we have known microorganisms annual dynamics changes and species of antagonistic fungus through the isolation, screening and identified to tobacco filed soil in Luoyang. This study will provent theory and application value to understant the structure and change of microorganisms from tobacco filed soil in Luoyang and use biological method to control tobacco geochory disease.