| Wheat Take-all is a devastating disease of wheat production which happens in varying degrees of northwestern spring wheat, northern winter wheat and middle and lower Yangtze River wheat growing region. It causes serious harm to our country’s wheat production. There are no effective disease resistant varieties or chemical control agent against this disease at present and using biocontrol bacterium to prevent wheat take-all is one of the effective measures to control it. Therefore, the author conduct the following experiments in order to screening for high biological control value bacterium against wheat take-all disease.Different measurement time of low-energy particle beam was used to irradiation induced AF stain Bacillus subtilis, and 3 measurement of 63 mutagenic treatment strains were obtained. Analysis of variance among variations in radius AR(AR=Rck-R) of 3 group treatment strain demonstrated that lower measurement time of mutagenizewas conductive to obtain more favorable dissociant, for the mean value of AR for treatment 1,2,3 was 0.0229,-0.0305,-0.0686 respectively and successively decreasing. Meanwhile, standard deviation of 3 treatments was 0.1159,0.1421, 0.1503 respectively and successively increasing which demonstrated that higher measurement time of mutagenize was conductive to obtain a larger range of bacterial strainvariation.AF stain Bacillus subtilis was induced and 3 kind of optimized antagonistic strains A2-3, A4-13, A6-10 was screened. Inhibition rate to Gaeumannomyces graminis var.tritici mycelia 1 growth had come to 84.52%,78.02%,81.32% respectively by plate confrontation culture method, which was 35.06%,24.74%, 31.96% higher than AF stains. By determining the inhibitory effect of metabolic product and high-temperature processingmetabolic product of optimized antagonistic strains to Gaeumannomyces graminis var. tritici we found that inhibition ratio has been decreased to 23.01%,35.81%,13.31% and 5.39% respectively. The result showed that the metabolic productof each strain which has an inhibitory effect to this pathogen was not a high temperature resistant material.Potted control effect test showed that wheat seed treated by AF strain, optimized antagonistic strain A2-3、A4-13、A6-10 coating process was able to prevent wheat take-all by 49.76%,58.52%,31.19% and 51.66%. Optimized antagonisticstrainA2-3 and A6-10 had a higher control effect of 17.60% and 3.81% than AF strain, while optimized antagonisticstrainA4-13 had a lower control effect of37.32% than AF strain. It may be attributed to a loss of ability to life in soil of A6-10 and A4-13 strains after inducing treatment. A4-13 decreased rapidly so that it had a good inhibition effect to Gaeumannomyces graminis var. tritici by plate confrontation culture method, but it didn’t have a good control effect when grow in soil.The influence of optimized biocontrol strain on wheat-growing showed that after coating process by bacteria liquid of Bacillus AF and optimized biocontrol strainA2-3, A4-13, A6-10, the growth of wheat was promoted. The plant height of wheat was 5.79%,9.87%,27.25% and 41.63% higher than control group. Mean dry weight was 46.01%,62.35%,5.12% and 41.91% heavier than control group. |
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