Plant growth promoting activity of different soil bacteria

Abstract

Plant growth promoting rhizobacteria (PGPR) are a group of bacteria that enhances plant growth by various attributes. Three Rhizobias, Azotobacter CBD 15, Pseudomonas striata,, Paenibacillus, Bacillus subtilis (T8), Bacillus licheniformis (T9), Bacillus licheniformis N14, Bacillus licheniformis N15, Lysinibacillus sphaericus (DGA) were screened for various plant growth promoting activity. They were also checked for antifungal activity against phytopathogenic fungi such as Fusarium oxysporum, Rhizoctonia solani. The growth was optimized at different temperatures for different bacterial species like 280C for Azotobacter CBD 15, Pseudomonas striata and three Rhizobias and 370C for Bacillus subtilis (T8), Bacillus licheniformis (T9), Bacillus licheniformis N14, Bacillus licheniformis N15, Lysinibacillus sphaericus (DGA) and Paenibacillus. Chickpea rhizobacteria, Pseudomonas striata and Azotobacter CBD 15 exhibited better production of indole acetic acid (IAA), whereas only Chickpea rhizobacteria and Pigeon pea rhizobacteria were also able to solubilise phosphorus. HCN production by Bacillus subtilis (T8), Bacillus licheniformis (T9), Bacillus licheniformis N15, Bacillus licheniformis N14 was positive. Ammonia production was observed by Paenibacillus, Bacillus subtilis (T8) and Pigeon pea rhizobacteria. The present study suggests that the use of bacteria as PGPR inoculants can be beneficial for crop cultivation as they can enhance plant growth due to the production of IAA, phosphate solubilisation and ammonia production. They can also have biocontrol activity as exhibited by HCN production and antifungal activity.