Abstract: Seventy-three rhizosphere bacteria were isolated from the rhizosphere soil of healthy tobacco collected from Qiannan tobacco growing area by dilution method. Dual culture method was used to study the inhibition of 73 strains on the Phytophthora parasitica var. nicotianae. The results showed that XPGJ05, YWGJ07, LSGJ04, WAGJ07 and LLGJ04 had strong antagonistic effect against P. parasitica var. nicotianae. The mycelial growth inhibition rates of XPGJ05, YWGJ07, LSGJ04, WAGJ07 and LLGJ04 were 52.7%, 51.8%, 53.9%, 51.2% and 59.5% with dual culture method, respectively. In metabolic liquid test, the mycelial growth inhibition rates were 71.9%, 78.3%, 68.7%, 69.2% and 64.3%, respectively. In the field experiment, the control effect on tobacco black shank of YWGJ07 was significantly higher than the control fungicide metalaxyl mancozeb and biocontrol agent. It is showed that YWGJ07 has potential application value. YWGJ07 was identified as Bacillus sp. by 16S rDNA sequence analysis.

Key words: tobacco rhizosphere bacteria, Phytophthora parasitica var. nicotiana, screening, antagonism