| Cruciferous clubroot caused by the obligate endoparasite Plasmodiophora brassicae, is recognized as a world-wide serious soilborne disease, associated with appreciable losses of cruciferous crops and hampered the development of oil and vegetable industry. To make better use of biological control of the clubroot,4antagonistic bacterial strains against P. brassicae have been screened out based on vitro and greenhouse tests, which were identified as Bacillus megaterium Y9, Pseudomonas putida Y16, Staphylococcus chromogenes Y26å'ŒMicrobacterium barkeri Z4by colony morphology, major bacteriological characteristics, Biolog identification, fatty acid methyl esters analysis(FAMEs) and16S rDNA sequence analysis. B. megaterium was developed into seed coating reagent, which could increase seed germination rate and enhance seed vigor. The test results showed that the seed coating reagent had quick drying speed, good membrane property and low swelling rate and its control effect reached62%. The survival rate of Bacillus megaterium Y9on the seeds was relatively high and its concentration was3×106CFU/mL after one year storage.In this study, chitosan/nano-TiO2composite was prepared at the most appropriate concentration ratio (0.10/0.50mg/mL) of chitosan and nano-TiO2. It could enhance the inhibitory effect of chitosan. The Fourier Transform Infrared Spectroscopy (FT-IR) result showed that chitosan/nano-Ti02composite did not change the original struture of chitosan, but closely combined through hydrogen bonds.For traditional method is difficult to accurately detect P. brassicae, we found special peaks of plant tissue infected with P. brassicae based on FT-IR. According to these special peaks, we can identify whether plant tissues have been infected by P. brassicae with the use of FT-IR. Moreover, a Real-time PCR quantitive detection model established was to detect clubroot samples collected in Zhejiang Province. Its amplification efficiency was112%and dectection range was from104-108spores/g. |
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