Using plant growth-promoting rhizobacteria to control soil borne plant diseases is an promising field in biological control. The objectives of this study were to determine the effect of plant growth-promoting of two biocontrol bacterial strains. They were screened from tobaccos rhizospheric soil and its controlling tobacco black shank. The experiment design was four treatments, including biocontrol bacterium YC0573 or YC0136 was applied as a soil drench respectively, metalaxyl mancozeb, and the disease control. The results showed that YC0573 and YC0136 reduced disease severity by 90.9%and 95.4%, both of them were better than metalaxyl mancozeb (86.4%);and the tobaccos growth of the treatments with YC0573 and YC0136 were better than control. The content of chlorophyll, leakage rate of electrolyte, and the activity of SOD, POD, PPO, PAL and CAT in 30 days, 60 days and 90 days after inoculation were determined, and the results indicated that PGPR strains YC0573 and YC0136 could control tobacco black shank effectively and promote tobacco growth. Both of the two strains could induce system resistance of tobaccos.

Plant growth-promoting rhizobacteria play an important role in plant growth.In order to investigate the effect of Brevibacillus brevis DZQ3 on tobacco growth and resistance of induction system,pot experiments were conducted in greenhouse and DZQ3 was inoculated into soaking root with filling root.Agronomic traits,biomass and chlorophyll content,leakage rate of electrolyte,systemic resistance related indices,including SOD,POD,PPO,PAL and CAT,and root development situation were measured.The results showed that the agronomic traits and biomass of tobaccos with application of DZQ3 were better than the control(CK),the difference were significant in 30 d.Systemic resistance related indices were better than the control(CK),the difference were significant in 60 d.These results indicate that PGPR strain DZQ3 can promote tobacco growth and induce system resistance,and also enhance disease resistant ability of tobaccos.