Effects of Allelopathy of Maize and Wheat Root on Soil Microorganism under the Plastic Film Mulching Condition

The amount of cultural bacteria,fungi and actinomycetes were mensurated by serial dilution-spread-plate method in rhizosphere and bulk soil of maize and wheat under the plastic file mulching modes in the arid and semiarid area in the northwest.Results showed that the number of bacteria,fungi and actinomycetes under the mulching was higher than it of conventional in rhizosphere of maize and wheat.Ratio of soil microorganism amount in the wheat and maize rhizosphere under plastic file mulching to conventional was positive.Effect of allelopathy of wheat root could increase the number of bacteria and actinomycetes in rhizosphere and bulk soil,while effect of allelopathy of maize could raise the fungi amount in rhizosphere.It was favorable to increase the number of bacteria and fungi in mico-environment of wheat and maize rhizosphere,that is the R/B1.The allelopathy of maize root could wide the gap of the bacteria and fungi number in rhizosphere and bulk soil of maize,that is R/B was higher.The number of actinomycetes increased in micro-environment of maize rhizosphere.The effect of allelopathy of wheat and maize was different to the number of soil cultural microorganism.The effect of allelopathy of wheat root could increase the amount of bacteria and actinomycetes,while maize could increase the soil fungi number in rhizosphere under mulching modes.The actinomycetes number of maize rhizosphere was more than it of bulk soil,while it was in contrast on wheat.