| Potato black scurf is a fungal soil caused by Rhizoctonia disease. In Gansu Province, Baiyin Jingtai County mountain farm potato planting in order cultivation mainly because of the limited arable land resources, even the obstacle is very serious,exacerbated by the occurrence of potato black scurf and other soil borne diseases.This study from a mountain farm do next selection of potato black scurf incidence of serious plant life potato plots in the healthy plants, collected from rhizosphere soil,separation, screening with good antagonistic effects on potato black scurf of bacteria,and the screening of the strain physiological and biochemical and molecular identification, ascertain the optimal growth conditions. To promote the detection of students and explore the mechanism of antagonistic substances, bacteria, biological control to Jingtai County of Gansu Province, Baiyin Hill Farm potato black scurf provides excellent biocontrol strains.First. By plate dilution method from the rhizosphere soil screening 96 strains for potato black scurf is antagonized the effect of strains, including 2 strains strongly inhibit strains QHZ-M1 and QHZ-M2 on the pathogen of potato black scurf, dual culture 3D inhibitory rate respectively 59.8% and 55.3%.QHZ-M1 in bacteria culture medium and incubation 2 colonies is very obvious, opaque colony, milky white,colony morphology is irregular in shape, circular and elliptical bacteria was rod-shaped, Gram stain blue is gram positive bacteria. QHZ-M1 physiological and biochemical determination, the result: glucose fermentation, malonate, citrate using positive, V-P test, contact the enzyme reaction, the test of ammonia production, to produce hydrogen sulfide were positive, with gelatin, tyrosine, tryptophan acid, the hydrolysis of starch to produce indole, tartaric acid salt hydrolysis, M-P test,phenylalanine hydrolysis were negative, and by automatically retrieves the database on the determination results of identification of the strains belonged to the genus of Bacillus.QHZ-M2 in the bacterial culture medium, the colony is opaque, milky white,the colony shape has irregular shape, the cell is in shape, Gram stain blue is gram positive bacteria. QHZ-M2 physiological and biochemical determination, the result:glucose fermentation, malonate, citrate using positive, V-P test, contact the enzymereaction, the test of ammonia production, to produce hydrogen sulfide were positive,with gelatin, tyrosine, tryptophan acid, the hydrolysis of starch to produce indole,phenylalanine hydrolysis, tartaric acid salt hydrolysis, M-P test were negative, and by automatically retrieves the database on the determination results of identification of the strains belonged to the genus of Bacillus.Through the physiological and biochemical identification and DAN 16 Sr identification of the two strains, the strains QHZ-M1 and QHZ-M2 were all belong to the genus bacillus, which were Bacillus axarquiensis and Bacillus atrophaeus.Second. Through of strain growth conditions research shows that: the optimum time for the growth of strain QHZ-M1 is after inoculation 16-34h; salinity 5 g / L; the optimal growth conditions is to sucrose as carbon source; temperature of 37 ℃; yeast extract powder as nitrogen source, initial p H is 7-8. The best time of QHZ-M2 growth was 16-36 h after inoculation; salinity 10g/L; the optimum conditions were sucrose carbon source; temperature 30-37℃; yeast extract as nitrogen source; the initial p H was 6-7.Strain QHZ-M1 and QHZ-M2 in the range of 4 to 45 degrees Celsius, p H5-10 can grow, can make use of carbon source and nitrogen source liquid over a wide range,indicating that the two strains of bacteria under the conditions of the field experiments have good survival ability, has as excellent biocontrol potential.Third. Through the study of the antagonistic mechanism of antagonistic strain,the strain QHZ-M1 has the ability to produce the long element IAA, the ability of phosphate solution, and the ability of producing iron carrier. Strain QHZ-M2 is capable of generating growth hormone IAA, phosphate solubilizing ability,siderophore production capacity, production capacity and production capacity.Pectinase protease. Constant temperature culture 48 h, strain QHZ-M1 produced a long amount of 4.86mg/L, strain QHZ-M2 produced a long amount of 10.35mg/L.And strains QHZ-M1 and QHZ-M2 processing four kinds of seed leaf spinach, pick not as cucumber, Corey yellow sweet F1 and black soybean seed germination number is higher than that of the control treatment(CK), bud length was significantly higher than that of the control treatment(CK), strain QHZ-M1 and QHZ-M2 all can promoteseed germination and seedling growth, and the better the effect of strain QHZ-M2.In summary, Bacillus axarquiensis.QHZ-M1 and Bacillus atrophaeus QHZ-M2 for potato black scurf had good antagonistic effect, and has a promoting role.Therefore, the two strains of bacteria has as good strains of potato black scurf biocontrol potential.Key words: potato black scurf; B.axarquiensis; B atrophaeus.; antagonist... |
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