Research Of Screening And Application Of The Bio-organic Fertilizer Strain Against Tomato Gray Mold

Tomato gray mold is a common soil-borne disease which does harm to tomato seriously. Chemical control of tomato gray mold is easy to produce negative effects, such as drug resistance, pesticide residues and ecological imbalance. Biological control has advantages of high efficiency, no pollution, no drug resistance and combining prevention with treatment. Bio-organic fertilizer has both superiorities of bio-fertilizer and organic fertilizer, which can not only increase production, improve product quality, but also regulate and improve the composition of soil microorganisms, and then reduce the dangers of crop diseases to some extent. Screening effective antagonistic strains of tomato gray mold and then preparing antagonistic agent and bio-organic fertilizer are important biotechnology ways to prevent and control tomato gray mold. The studies on solid fermentation of antagonistic strains are less involved at home and abroad. Relative to the preparation of agents by liquid fermentation and solid fermentation have many advantages including low cost, high efficient strains number, making simple, storing and transporting easily, etc, while the studies on solid fermentation of antagonistic strains are less involved at home and abroad. Therefore, the experiment aimed to screen and identifit an antagonistic strain which had a good inhibitory effect on Botrytis cinerea through purification of the separation of soil microorganism, and to optimize the solid fermentation medium and culture conditions through the single and orthogonal test, and to study the preservation way of the antagonistic strain, and to make bioorganicfertilizer by fermenting the mixture of antagonistic strain and the decomposed organic fertilizer, and then to study its control effect on tomato gray mould by indoor pot experiment.1. Isolation, screening and identification of the antagonistic strain of tomato gray mold in soil. In order to get the antagonistic strain which had inhibitory effect on tomato gray mold and then confirm the taxonomic status of it, the strains of soil samples were isolated by the methods of dilution coated tablet and streak plate, and then screened by tablet confrontation. Furthermore, they were identified by morphological and ITS sequence analysis.{Penicillium oxalicum)* The result showed that 47 fungis were isolated from soil samples.27 fungis among them were screened initially, which had antagonism effect on Botrytis cinerea. Furthermore, a strain of number Z47 was rescreened, that had the best inhibition effect and its inhibition rate reached 74.80% on the Botrytis cinerea. The strain of number Z47 was identified as Penicillium oxalicum.2. The optimization of antagonistic strain solid fermentation conditions and study on its agents preserved ways. In order to study the solid fermentation conditions and preservative way of the antagonistic strain Z47, the experiment explored the solid medium, added carbon source, added nitrogen source, added phosphorus, the ratio of material to water, the amount of solid material bottled, inoculation amount, illumination, fermentation temperature and time influence on the sporulation quantity through single factor and orthogonal test; Then studied the different ways to save the antagonistic strain Z47 agents, and measured spores and the effective number of living bacteria regularly. The optimal conditions for solid-state fermentation of the strain are obtained as following:15g solids every 250 mL erlenmeyer flask, the proportion of powdered rice hulls to bran and solid material to water are 4:1 and 1:0.6 (g-mL-1), respectively, plus maltose, ammonium sulfate and dipotassium hydrogen phosphate are 1.5%,2% and 0.15%, respectively, inoculums 12.5%(mL·g-1), cultures in the dark, the fermentation process is at a fluctuant temperature of 25℃-20 ℃-28℃ for 2 days, respectively. The spore numbers are up to 5 X 109 CFU/g after 12 days under this optimal fermentation conditions. The antagonistic strain Z47 spore survival rate of wet sample deposited at 5℃ had been high. But from the living strain number of the antagonistic strain Z47,40 ℃ drying samples stored at room temperature was significantly higher than that wet sample deposited at 5℃, stored at room temperature and 40 ℃ drying wet sample deposited at 5℃. Therefore, the best way of preserving the antagonist Z47 agent was stored at room temperature after drying it under 40℃.3. The production of antagonistic Z47 biological organic fertilizer and its applied research in pot experiment In order to produce the antagonistic Z47 biological organic fertilizer and research its biocontrol effects on tomato grey mould and microorganism of soil, the fermentation mixture of the antagonistic strain and decomposed organic fertilizer was applied to tomato pot experiment, and the occurrence of tomato grey mould and the tomato rhizosphere soil microbes change were detected on a regular basis, and at the end of the pot experiment the biomass of tomato was measured. The results showed that the effective number of living antagonistic strain in the Z47 biological organic fertilizer was more than 2× 108 CFU/g. The control effect of tomato gray mold by applying biological organic fertilizer which was rich in antagonistic strain Z47 was up to 73.67%(treatment 5), which was significantly higher than the treatment of antagonistic strain Z47 liquid (treatment 3) and ordinary organic fertilizer (treatment 4); The tomato plant height, stem diameter, fresh weight and dry weight of treatment 5 were also significantly higher than other treatments, which showed significant effect on the growth-promoting; compared with other treatments, treatment 5 made the number of tomato rhizosphere bacteria and fungi dramaticly increase and the number of bacteria and actinomycetes significantly reduce, and the antagonistic strain Z47 number among which was also significantly higher than treatment 3. The antagonistic Z47 biological organic fertilizer could improve soil microbial community structure in tomato rhizosphere, improving stability and disease suppression of soil microbial ecosystem, thereby improving soil quality and playing a role in disease prevention and growth promotion.