The rhizosphere effect of soil microbes in Yanbian tobacco-growing area

Bacteria,fungi,actinomycetes,and six physiological groups from three types of soils producing different quality tobacco leaf in Yanbian area were studied by plate-count method.Results showed that there were obvious rhizosphere effects.The R/S values of total microbial population ranged from 1.19 to 3.07,and those of bacteria,fungi,and actinomycetes ranged from 1.21 to 3.12,1.37 to 4.36,and 0.73 to 4.71,respectively.Rhizosphere effects showed significant variation between different soils,especially in dark brown soil.Further research indicated ammonifying bacteria,nitrite bacteria,nitrifying bacteria,and aerobic cellulose decomposing bacteria played a positive role on rhizosphere effects,while effects of aerobic nitrogen-fixing bacteria and potassium bacteria depended on soil type and tobacco growth stages.It's concluded that rhizosphere effects of microbes in dark brown earth was significantly higher.It may be one of the reasons that quality of tobacco leaf produced in dark brown earths was better than that in the other two types of soils.