Siderophore production by rhizosphere bacteria contributes to fungal growth inhibition resulting into suppression of plant diseases. Therefore, siderophore-producing Pseudomonas isolates were studied for root rot disease control and plant growth stimulation of green gram. Fifty-eight Pseudomonas strains were obtained from the rhizosphere soil of chickpea and green gram using dilution plating technique. These strains were tested for siderophore production on MM9 medium and succinate medium plates containing chromo-azurol S by spot test method. Siderophore-producing strains formed the halo zone around the colony growth and diameter of halo zone varied with different Pseudomonas strains. Siderophore production was found more on MM9 medium as compared to succinate medium. Bacterial colony growth (G) and halo zone (H) size ratios varied from 1.44 to 10.24 in different Pseudomonas strains on MM9 medium. Siderophore-producing Pseudomonas strains inhibited the growth of phytopathogenic fungi i.e., Fusarium oxysporum, Rhizoctonia solani and Pythium aphanidermatum. Large zones of fungal growth inhibition were observed on PDA medium in comparison to nutrient agar medium plates. Seed inoculation of Pseudomonas cultures in green gram (Vigna radiata L.) caused reduction in root rot disease (R. solani induced) symptoms under pot house conditions and disease control varied from 33.4 to 100% with different Pseudomonas cultures. Coinoculation of different Pseudomonas strains with Bradyrhizobium strain SMR15 in green gram also enhanced the nodule number, nodule fresh weight and plant dry weight at 30 and 60 days of plant growth. Coinoculation of Pseudomonas strain CP56 with Bradyrhizobium strain and R. solani showed maximum 275.8% increase in plant dry weight at 60 days in comparison to control uninoculated plants and completely suppressed the root rot disease under pot house conditions. Thus, inoculation with siderophore-producing Pseudomonas sp. could be utilized for disease control and plant growth promotion of legumes. PDFFulltextXMLReferencesCitation
How to cite this article
G.K. Sahu and S.S. Sindhu, 2011. Disease Control and Plant Growth Promotion of Green Gram by Siderophore Producing Pseudomonas sp. Research Journal of Microbiology, 6: 735-749.
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