Screening Biocontrol Strains And Researching The Control Of The Atractylodes Macrocephala Koidz

Root rot(mainly caused by Fusarium oxysporum Schlecht) is one of the most important diseases of Atractylodes macrocephala Koidz. in the main producing regions in Guizhou Province. Currently, chemical pesticides is the main method to control of root rot of A. macrocephala, but environmental pollution and pesticide residues are the main problems of chemical pesticides. In biological control, the beneficial microorganisms are used to inhibt the growth and spread of the pathogens. Environmentally and efficiently, biological control is a hot research direction and had broad prospects. This paper researched the biological control of root rot of A. macrocephala. Screening biocontrol bacteria, funguseses and actinomyces, what could agaist the pathogens. The main issues were about researching the inhibitory effect, biological characters, researching the better fermentation conditions of producting antibiotic, and field test study.The main research results were summarized as follows.1. Biocontrol strains separation, screening and identification.1061 strains isolated from soil, among them 58 strains had inhitory effect, in which, 7 funguses, 12 bacteria and 5 actinomycetes had been saved. Through morphological, physiological and biochemical and molecular indentification, the 7 funguses were identified as Trichoderma, included T. asperellum, T. koningiopsis, T. longibrachiatum and T. viride. The 12 bacteria were identified as Bacillus, included B. amyloliquefaciens, B. amyloliquefaciens subsp., B. subtilis and B. methylotrophicus. The 5 actinomycetes were identified as Streptomyces, included S. hygroscopicus, S. ahygroscopicus and S. rutgersensis.2. The biological characteristics and culture conditions of biocontrol strains.The biocontrol Trichoderma were cultured in different medium, temperature, illumination, pH, carbon source and nitrogen source. The results showed as follows: PDA and oat medium, pH4~6 were suitable for growth; best culture temperature was 27.5~30?; light had no effect in growth; the best carbon source for growth were glucose, lactose and maltose; the best nitrogen source for growth were peptone and NH4 Cl. As M216-1 showed good antibacteria effect, we used it to study the liquid fermentation conditions, the optimum fermentation conditions were as follows: Lactose 20 g, peptone 2g, NaCl 0.5g, FeSO4 0.01 g, MgSO4 0.5g, CaCO3 1g, K2HPO4 0.5g, H2 O 1000mL. pH 6, liquid volume was 40 m L/250 m L, inoculation was 3%, 28? 160 rpm fermentation 72 h.The biological characteristics of biocontrol bacteria: The range of temperature for growth well was 30~45?; intolerance acidic, and pH less 5 could not grow. Almost biocontrol bacteria could grow on the medium which salt content more than 10%; and they were all aerobic bacteria. As B-7 showed good antibacteria effect, we used it to study the liquid fermentation conditions, the optimum fermentation conditions were as follows: Sucrose 20 g, yeast extract 2g, NaCl 0.5g, FeSO4 0.01 g, MgSO4 0.5g, CaCO3 1g, K2HPO4 0.5g, H2 O 1000m L.pH 7, liquid volume was 40mL/250 m L, inoculation was 2%, 30? 180 rpm fermentation 48 h.Biocontrol actinomycetes growing best at 30?; and could not grow on the medium which salt content more than 15%; the best carbon source for growth were Soluble starch, maltose, lactose and glucose; the best nitrogen source for growth were peptone, beef extract and yeast extract. As F-11 showed good antibacteria effect, we used it to study the liquid fermentation conditions, the optimum fermentation conditions were as follows: Soluble starch 20 g, yeast extract 2g, NaCl 0.5g, FeSO4 0.01 g, MgSO4 0.5g, CaCO3 1g, K2HPO4 0.5g, H2 O 1000mL. pH 7, liquid volume was 40mL/250 m L, inoculation was 5%, 30? 160 rpm fermentation 96 h.3. The effect of field control by biocontrol strainsThree types of biocontrol agents used for field trials,all of them could reduce the degree of root rot of Atractylodes macrocephala, and control this disease. Among them, the control effect of Streptomyces was 77.91%; the control effect of Bacillus was 62.87%; the control effect of the Trichoderma was 56.71%.