Intercropping Soybeans, Mung Beans On The Impact Of Tobacco Soil Microbe

Tobacco black shank caused by Phytophthora nicotianae, is one of the main destructive diseases of tobacco in the world. It results in serious loss owing to the aggravation recently in Chongqing.This is a research that tobacco intercropping Soybean or Mung bean in regulating the microorganisms to impact even control of the Tobacco Black Shank disease. The investigation included the change of soil microorganism amount in the intercropping tobacco fields with Soybean or Mung bean, and the difference of the antagonism on Phytophthora nicotianae, and the numbers'distribution contrast of Tobacco Black Shank pathogens in the soil.1. By the determination of the number of midseason and autumn soil microbes in intercropping tobacco fields, the results showed that, Mung bean or Soybean rhizosphere soil microbes of intercropping tobacco fields were significantly higher than the total amount of tobacco rhizosphere.The numbers of soil bacteria and actinomycetes in Mung bean or Soybean rhizosphere in the same period were both higher than that in tobacco rhizosphere, but the number of soil fungi showed the opposite results.The total amount of micro-organisms in Soybean rhizosphere was higher than that in Mung bean rhizosphere.2. The bacteria and actinomycetes isolates were tested against Phytophthora nicotianae by plate confrontation in order to count the number of antagonists. The results showed that, the number of antagonistic bacterial and actinomycetes isolates against Phytophthora nicotianae isolated from Soybean and Mung beans rhizosphere was higher than tobacco rhizosphere in fast growing and harvest period.The proportion antagonistic bacteria in bacteria isolates was low, while the proportion of antagonistic actinomycetes in the total isolates was comparatively high. The number of antagonistic bacteria in tobacco field declined with tobacco growing, while the change trend of the number of antagonistic actinomycetes was contrary to bacteria.3. By trapping method of tissue and selective oat culture medium, the isolates were quantified when they were identified as Phytophthora nicotianae in soil microbes of the intercropping tobacco fields. The results of identification showed that the isolates were actually Phytophthora nicotianae.Experimental data analysis results showed that the quantity of Phytophthora nicotianae in Mung bean or Soybean rhizosphere soil of intercropping tobacco fields was lower than the number of the tobacco rhizosphere.