Long-term activity of bio-priming seed treatment for biological control of faba bean root rot pathogens

The long-term activity of some antagonistic fungal and bacterial agents against the incidence of faba bean root rot incidence was evaluated when applied as a bio-priming seed treatment. The inhibitory effect of antagonistic fungi and bacteria against the linear growth of root rot pathogenic fungi was evaluated in vitro. The tested inhibitor factor in this study was the antagonistic agents applied as either growth culture discs or bio-primed faba bean seeds. The inhibitor effect of Trichoderma viride, T. harzianum, Bacillus subtilis and Pseudomonas fluorescens was significantly higher than T. hamatum and B. cereus, respectively. Similar results were also obtained when the antagonistic agents were applied as bio-primed seeds. Under greenhouse conditions, all the tested fresh and 2 months-stored, bio-primed faba bean seeds showed a highly significant effect causing complete reduction of root rot incidence at both pre- and post-emergence stages of plant growth compared with the control treatment. Stored seeds at 4 and 6 months showed a less protective effect against the incidence of disease. After 3 months of storage under field conditions, the antagonistic agents could protect seeds against infection by root rot pathogens at both pre- and post-emergence stages. However, after 6 months of storage, a lower protective effect was observed. No significance was observed between seeds primed only with adhesive agents and the untreated control. Promising applicable techniques could be suggested in light of the results obtained in the present study. The use of bio-primed seeds might be considered as a safe, cheap and easily applied biocontrol method against these soilborne plant pathogens.