Study on Population Density and Distribution Characteristics of Endophytic Bacteria in Tobacco in Yunnan

In the study,some bacteria strains were isolated from different tissues of tobacco collected from different regions in Yunnan by the method of grinding separation. The population density of endophytic bacteria in different cultivars and tissues of tobacco at different growth stages in different planting areas were studied. The results showed that there were a lot of endophytic bacteria in root,stem and leaf of the tobacco plants. The population density of endophytic bacteria varied with different cultivars,different tissues,different growth stages and different planting areas. The distribution of endophytic bacteria had season preference,tissue specificity and growth-stage heterogeneity. Some of them were resident flora,others were transient flora. The amounts of endophytic bacteria in maturing stage were most. The distribution laws of the bacteria population density in Yunyan85,KRK26,K326,Hongda were roots leaves stems,leaves roots stems,leaves roots stems,roots leaves stems. The germ carrying amounts in four growth stages were in alternative changing process with the fluctuation amplitude of germ amount of 2. 6- 4. 96 log cfu /g. fw. The endophytic bacteria with a higher frequency in tobacco were Bacillus sp.,it include Bacillus pumilus,B. amyloliquefaciens,B. licheniformis,B. subtilis,B. megaterium,B. flexus,B. simplex,Bacillus cereus. They were therefore considered as the dominant genera of endophytic bacteria in tobacco. The population density of endophytic bacteria varied with different areas. The studies on population dynamics could provide fundamental theory for biological control of tobacco insects and promoting growth.