Impact of Co-Inoculation with Rhizobium leguminosarum and some Plant Growth Promoting Rihzobacteria against Rhizoctonia solani and Fusarium oxysporum Infected Faba Bean

Plant Growth Promoting Rhizobacteria (PGPR) were evaluated individually or in combination and compared to the fungicide Topsin M-70® for their antagonistic activities and suppressive actions against Fusarium oxysporum and Rhizoctonia solani severally, which were deemedthe causal agents of root rot and wilt diseases of faba bean plants. In vitro, most of the examined strains showed eminent abilities to inhibit mycelial growth of Rhizoctonia solani or Fusarium oxysporum. Strains of Rhizobium leguminosarum (No.9), Azotobacterchroococcum (No.12) and Pseudomonas fluorescens (No. 6) recorded the highest inhibition zone against two tested pathogenic fungi and were used in the present study. Generally, under greenhouse and field conditions, all the tested PGPR strains significantly reduced root-rot and wilt incidence and increased the percentage of survived plants compared to control (infested soil). Combination among R. leguminosarum+ A. chroococcum + P. fluorescens was more effective in controlling root-rot and wilt diseases, increasing growth parameters, yield components, photosynthetic pigments, activities of nitrogenase, dehydrogenase and total phenols. Obtained results clarified the importance of PGPR in controlling pathogenic fungi, enhancing growth parameters of faba been plants compared to chemical fungicide and lowering chemical fertilizers application.