Biochar adsorbs beneficial airborne bacteria to inhibit wheat Fusarium head blight

Background and aims

Wheat Fusarium head blight (FHB) is a soil-borne disease that is caused mainly by Fusarium graminearum (Fg). Biochar is a soil amendment with the potential to suppress leaf and soil-borne diseases. This study aimed to investigate the effects of microorganisms colonizing biochar on the occurrence of wheat FHB.

Methods

We explored the inhibitory effect of biochar extract on wheat FHB using field experiments and validated the colonization of airborne microorganisms on biochar via amplicon sequencing. In addition, the beneficial bacteria in the biochar extract were isolated, screened and validated using greenhouse pot experiments.

Results

We found that biochar extract inhibited wheat FHB by greater than 50% and increased the field yield by 6.37%. The microorganisms in the biochar extract inhibited Fg growth. Biochar adsorbed different airborne microorganisms, and the relative abundances of Bacillus and Pseudomonas gradually increased with increasing adsorption time. Of note, two Bacillus species and one Pseudomonas species isolated from biochar exerted antimicrobial effects through direct antagonism or the production of antifungal substances. Furthermore, the results of the pot experiments revealed that Bacillus S86 treatment was more effective against FHB in both the mixed and single-strain treatments.

Conclusions

In this study, we provide new evidence that biochar can adsorb beneficial airborne bacteria to control wheat FHB. The design of biochar-beneficial microbe mixtures to suppress targeted soil diseases is worthy of further investigation.