| Wheat take-all is a disease which is caused by Gaeumannomyces graminis var. tritici violating the roots and quite widely distributes in all parts of our country, which seriously affects the wheat production in China. There is still a lack of effective wheat take all disease resistant varieties, mainly by crop rotation and chemical control. But because the wheat take-all fungus could live for a long time in the soil and the wheat was the main food crop, the rotation is not realistic for a long period of time. Chemical pesticides can only remove seeds that carry pathogens, can’t eradicate pathogens in the soil. And there had lots of problems, such as the high remain, the environmental pollution, and the resistant. The inhibitory action and biological control can make a large number of enrichment in the soil, Can interact to pathogenic bacteria in the soil for a long time. Therefore, biological control has become the research focus of disease prevention and control of wheat take-all. This test separate and screened one Bacillus strain with the stronger antagonist activity against Gaeumannomyces graminis var. tritici from the onset soil, and From the morphological observation of the effect of Biocontrol Strain of Gaeumannomyces graminis. The control effect and the growth-promoting effect to the wheat of the strain were studied, which laid a foundation for the development of an effective bio-control bacteria agent.306 bacillus strains were isolated from the onset soil in He Bei Province and four strains with higher antagonist activity against G. g. t. were obtained. With the bacteriostatic bandwidth of 2.90 cm, the strain Z-9 showed the highest antagonist activity. The hyphae in the edge of inhibition zone was picked for microscope observation. It was found that strain Z-9 could make the hyphae of G. g. t. expand and breakage. By observation of the colonies, bacteria, and spore morphology, physiological and biochemical characteristics tests and 16 S r DNA sequence analysis, strain Z-9 was finally identified as Bacillus methylotrophicus.This research through the single-factor test and orthogonal test This study determined by single factor experiment and orthogonal experiment finally The optimum conditions for fermentation corn flour 1.00%、soybean meal 2.00%、Mn SO4·H2O 0.04%、Mg SO4·7H2O 0.04%,and p H value was 7.5, with fluid volume was 50 m L/250 m L, 37℃ cultivate 36 h. The optimized spore yield(1.60×109CFU·m L-1) increased 9.60 times comparing to the non- optimized(1.50×108CFU·m L-1). Lay the foundations for the further research and application of the strains.It is the necessary conditions of bio-control bacteria agent that does not negatively affect crop growth and development after applying it. So this study first has carried Wheat germination and growth acceleration test on Z-9 bacteria agent. Take 20 grains of wheat seed that had been surface disinfection on the filter paper(ф 8.5 cm) that had been soaked on 2.00 m L Z-9 bacteria suspension in the sterilization of wetting AGAR(ф 9.00 cm), In 28 ℃incubator on wheat seed sprouting growth test, With 2.0 m L sterile water soak filter paper as ck. Measure the root length and shoot length after three days. The result showed that when the concentration was 1.00×109~1.00×1010 CFU·m L-1, both of averaged bud length and root growth reached longest, increasing by 55.30% and 46.90%, respectively, compared with the control group. Show that the bacterium agent can promote the growth of roots and shoots after wheat seed germination, but the germination rate of wheat seed was not affected.On the basis of the bacteria agent can promote the growth of wheat, the prevention and control of potted experiment was carried out, inspection the bacteria agent on wheat disease control effects. The potted test for bio-control was done by using wheat seeds after three treatments(seed, seed soaking, pouring) with inoculation on the pathogen bread. After 30 days later, Detection of wheat total eclipse disease situation and measurement of wheat root length, root weight, plant height, plant weight. The result showed that all three treatments had certain control effect, the pouring treatments showed the best effect, By the concentration of 1.00×109~1.00×1010 CFU·m L-1, the control effect reached as high as 58.04%, and all the average root length, plant height, root weight also showed the largest growth. Respectively increased 532.23%、80.65%、44.44%、363.15%, compared with the control group. It provided the basis for the strain with the best application methods. |
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