In vitro antagonistic activity of Pseudomonas spp. against Rhizoctonia soloni

The present research work deals with the in-vitro study of antagonistic activity of Pseudomonas spp. against plantpathogenic fungi Rhizoctonia soloni. The bacterial strains were isolated from rhizospheric soil of Korea district of Chhattisgarh. A total of 28 bacterial cultures were isolated from 25 representative soil samples collected from five blocks of Korea district of Chhattisgarh, out of which four were identified as Pseudomonas spp. (PKS10- Pseudomonas syringae, PKM11- Pseudomonas syringae, PKJ25- Pseudomonas alcaligenes and PKB27- Pseudomonas alcaligenes) from Plant Pathology Division, IARI Delhi. These four Pseudomonas spp. were examined for their ability to antagonize R. soloni in in vitro plate assay by dual culture inoculation along with the standard check (Pmtcc- Pseudomonas isolate from IMTECH Chandigarh). The antagonistic activity was interpreted by restricted growth zone of the fungal pathogen in dual culture. The diameter of hyphal growth of the fungi in dual culture with isolates PKS10, PKM11, PKJ25, PKB27, Pmtcc and control were 3.82, 3.68, 2.73, 3.41, 3.25 and 7.3 cm respectively. All the four Pseudomonas isolates PKS10, PKM11, PKJ25, PKB27 and Pmtcc (standard check) inhibited the hyphal growth of Rhizoctonia spp. by 47.67, 49.58, 62.60, 53.28 and 55.47% respectively. One among four Pseudomonas isolates, (PKJ25) P. alcaligenes was found to suppress the growth of fungal pathogen significantly in dual culture by 62.60% and was more effective than other isolates. This study suggests that P. alcaligenes isolates might be used as potential biological control agents against plant pathogenic fungi Rhizoctonia soloni. Key words: Antagonism, biological control, Pseudomonas alcaligenes, Rhizoctonia soloni.