Interaction of Bacillus amyloliquefaciens and Azospirillum oryzae on wheat growth promotion and Fusarium graminearum disease inhibition

Co-inoculation of plant growth promoting bacteria and biological control agents, is a strategy to improve health, yield and quality of crop production. The objective of the present study was to evaluate interactions of two bacterial strains, Bacillus amyloliquefaciens UTB96 and Azospirillum oryzae NBT506, on growth promotion of wheat and control of the causal agent of Fusarium head blight, Fusarium graminearum. The results showed that single and co-culture of these strains inhibit mycelium growth of F. graminearum by direct inhibition and volatile organic compounds. In germinator assays, different wheat growth features were increased and disease index was decreased. Results showed that co-inoculation or single application of the bacteria in the soil significantly enhanced root length (14-80%), root fresh weight (18-167%), root dry weight (4-110%,), shoot length (17-61%), shoot fresh weight (47-169%) and shoot dry weight (up to 90%). In addition, a significant decrease in disease index (62-100%) was observed in different single and co-culture treatments. In conclusion, the studied two bacterial strains showed synergistic effects on wheat growth promotion and fungal growth inhibition.