Cultural Filtrate of Rhizobium spp. and Arbuscular Mycorrhiza are Potential Biological Control Agents Against Root Rot Fungal Diseases of Faba Bean

Abstract

3 Abstract: A field experiment was conducted in 2005/2006 and 2006/2007 to evaluate the potential antagonistic activity of the cultural filtrates of the three wild rhizobial isolates M. L (R1), L. C (R2), T. S (R3), 41 R. leguminosarum ICARDA 441 (R4) strain and arbuscular mycorrhiza (AM) fungi in the biocontrol of damping- off and root rot diseases of faba bean plants, when applied in individual or combined treatments, under naturally infested soil with pathogenic fungi: Rhizoctonia solani, Fusarium spp. and F. solani. The bioassays of the rhizobia were tested. All treatments reduced the damping-off and infected plants as compared with untreated control. The combined treatment R2 + AM was the most effective treatment; it gave the lowest percentage of damping-off (6.67 and 8.89) and the highest percentage of healthy plants (86.58 and 83.33) in the two seasons, respectively. Beside the effect on disease control, seeds treatment with culture filtrates of the tested rhizobia or AM fungi in individual or combined treatments improved plant growth as indicated by the increased plant shoot height, root nodulation by native rhizobia, shoot dry weight and seeds yield of faba bean plants in the two trials, especially combined treatment R2 + AM. On the other hand the used rhizobia especially, isolate (L. C ), proved to be IAA, exopolysaccharides and chitinase producers. The soaking of faba bean seeds 4 in cultural filtrates of Rhizobium spp. individually or in combination with AM fungi acts as a bioprotection agents against faba bean plant root rot diseases, in addition to increasing plant growth and yield.