| A quantitative field test has been completed for the paper, which defined the nutrients including nitrogen, phosphorus, potassium,organic fertilizer and micronutrient and environmental factors including soil density, moisture, pH,and temperature on the major numbers of soil microorganisms for Soybean Root Rot , which provides the basis for regulating and controlling Soybean Root Rot .Fertilizer N have various effects on pathogenic microorganisms for Soybean Root Rot . When 120kg/hm~2 of fertilizer N was applied.The number of Penicillium in the flowering period. The number decreased 53.8% comparing with the trwatment of non-fertilization N. However, 200kg/hm~2 of P was used Fusarium spps and Rhizoctonia solanis have been the greatest restraint, their number decreases 13.5% and 71.7% respectly comparing with the trwatment of non-fertilization P. Combined borax (854.0 g/hm~2) and zinc sulfate (133.1 g/hm~2) was applied the restraint to Penicillium , Its number decreases 12.1% comparing to antithesis ; While only application of zinc sulfate (133.1 g/hm~2) have the best effect on reducing the number of Fusarium sp and Rhizoctonia solani respectively, and the reducing was 30.7% and 12.5% .Applying 4000 kg/hm~2 of Organic fertilizer ,the numbers of bacteria and Actinomycetes increased 94.1% and 183.0 % than the comparison treatment respectively; It combined application have the biggest promoting role for the bacteria which increased 176.0 % than the comparison in micronutrient,borax (854.0 g/hm~2),zincsulfate ( 133.1g/hm~2) and ammonium molybdate (67.5 g/hm~2) ; However ,the single application of zinc sulfate (133.1 g/hm~2) on Actinomycetes has role in promoting the most Better than the controlling increased by 176.0 %.The experiment result showed the number of micro-organisms and non-pathogenicin was different between the soybean rhizosphere and non-rhizosphere in different crop succession . In the continous cropping rhizosphere, the number of Fusarium spp,Penicillium and Rhizoctonia solani were more83.8%, 55.29%, 80.4% respectively than their non-pathogenic, and their number in cropping rhizosphere are higher 74.71 %, 46.76 %, 71.1 % respectively than their non-rhizosphere; and in rotation cropping rhizosphere are higher74.4 %, 46.2%, 58.7 % respectively than in their non-rhizosphere; In the continous cropping rhizosphere are higher 109.17 %, 93.68%, 111.21 % respectively than in the rotation cropping rhizosphere . In the non-micro-organisms of root rot, the number of bacteriums and actinomycosis in rhizosphere are more than in non-rhizosphere in the different stage , but in the rotation cropping and stubble cropping'rhizosphere are higher than in continous cropping obviousiy.The result showed that the appropriate soil density for Fusarium spp was 1.0 g/cm3 in different environment conditions。When the soil density was 1.4 g/cm3 ,the inhibitory effect on their numbers was 61.0%. The suitable soil moisture was17.44% and when the moisture was 38.12%, the inhibitory effect on the numbers was 51.0%. The suitable soil pH was about 5.0 and soil pH was 8.5 its inhibitory effect on Fusarium spp was 79.5% . The 25℃temperature was suitable for Fusarium spp ,a inhibitory effect of for32.3% was occurred when the . temperature got at 35℃For the Rhizoctonia solani ,the most appropriate soil density was 1.1 g/cm3,its number was reduced 39.4% in 1.3 g/cm3 of soil density. The appropriate soil moisture was 34.35%, its numbers had a reducing of 38.4% when soil moisture was 10.61% and the The most appropriate pH is 5.0 ,there was a restrained effect of 67.3% in the pH of 8.5. The appropriate temperature is 25℃,there is a restrained effect of 32.3% in 35℃.for the Penicillium ,the appropriate soil density is 1.1g/cm3 , when the density was 1.4 g/cm3,the number of Penicillium was decreased 54.1% .The appropriate soil moisture is 10.61%, and the number was decreased 47.6% when the moisture was 38.12%. The appropriate pH was 5.0, its number reduced 65.9% in the 8.5 soil of pH. The appropriate temperature was 30℃the number was reduced 22.3% in 35℃.For the Bacteria the appropriate soil density was1.0 g/cm3, its number dropped 23.4% in the 1.3 g/cm3 of soil density . 38.12% was the suitable soil moisture for the Bacteria , when the moisture was 10.61%,its number decreased 60.2%.The appropriate soil pH was 8.5 for the Bacteria, and appropriate temperature was 30℃45.7%of the numbers was restrained in the condition of 15℃. For the Actinomycosis the appropriate soil density is 1.0 g/cm3 , 17.4% of its number was reduced. when soil density was 1.3 g/cm3. The appropriate moisture is 10.16% when the the soil moisture was 34.35% ,its numbers decreased 77.8%, The appropriate soil pH is 8.5 for the Actinomycosis , and the appropriate air temperature was 35℃, its number reduced 31.4% in 15℃.The experiments results showed those factors mentioned above had effects on the disease severity of Soybean Root Rot, and the soil pH has the highest effections on the disease severity of Soybean Root Rot, secondary soil density and temperature has minimal impact. In different crop succession, the disease severity of Soybean Root Rot was tentatively effected by the Continous Croping.According to the above experiment conclusion: In order to reduce the loss of Soybean Root Rot, the number of pathogens must be reducd and the number of beneficial bacterium be raised. Applying proper quantities of P, K and organic fertilizer and reducing N and changing the soil pH suitable,thus the number of Fusarium sp,Rhizoctonia solani could be reduced and the number of bacteria and actinomycosis could be raised . |
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