Response of pH on indigenous biocontrol activity of fungal and bacterial biological agents against Rhizoctonia solani

摘要

Root rot incited by Rhizoctonia solani is one of the major diseases of peas. As there are no long-term management strategies for this soil-borne pathogen, therefore, the study was carried out to determine the effect of pH on the antagonistic activityof fungal and bacterial isolates (Th3 and Th5 (Trichoderma harzianum), Anl (Aspergillus niger), Po3 (Penicillium oxalicum) and PS1, PS2, and PS5 (Flourescent Pseudomonas) against Rhizoctonia solani at four different pH levels (5.0, 6.0, 7.0 and 8.0). Allseven indigenous fungal and bacterial isolates evaluated for their antagonistic potential against root-rot pathogen significantly retarded the radial growth of R. solani in comparison to control at four different pH levels (5.0, 6.0, 7.0, and 8.0). Theobservations of the study revealed that all bio agents significantly inhibited the growth of R. solani. Similarly, Trichoderma species had significant effects on the number and size of sclerotia. The pH range of 6.0-8.0 was found optimum for Trichodermaspp. while Fluorescent Pseudomonas showed the best antagonistic activity at pH 7.0. As far as the effect of pH levels is concerned, all the promising fungal and bacterial isolates caused maximum growth inhibition of test pathogens at pH 6.0 to 7.0.