Characterization and Plant Growth Promoting Aspects of a Novel Phosphate Solubilizing Brown Sarson Endophyte Pseudomonas fluorescens Strain smppsap5 Isolated from Northern Himalayas of India

The present study was conducted to reconnoiter the potential of endophytic bacterium of brown sarson root tissues, Pseudomonas fluorescens strain smppsap5 for enhancing the growth of brown sarson plants under organic agriculture of Jammu and Kashmir, India. The novel bacterium strain smppsap5 isolated was identified as Pseudomonas fluorescens using 16S ribosomal RNA gene sequencing. The isolated strain was selected among 81 isolates for highest phosphate solubilization activity in terms of the phosphate solubilization index (3.19) and phosphate released (313.58 mg/L) from tri-calcium phosphate in the liquid assay. The optimal phosphate solubilizing activity of the strain was determined with different incubation periods and nitrogen sources. It was observed that maximum phosphate solubilization occurred in presence of the nitrogen source tryptone and incubation period of 72h and phosphate solubilization was minimum among all with nitrogen source NaNO3 and incubation period of 24h. The effect of temperature and PEG on growth of this strain was also observed besides many metabolic, physiological and biochemical attributes. The beneficial effect of Pseudomonas fluorescens strain smppsap5 in brown sarson plants was observed in terms of root shoot length, germination percentage, chlorophyll content, oil content and other yield attributes besides its inoculation impact on soil physio-chemical and biological properties. The results from the present study suggested that Pseudomonas fluorescens strain smppsap5 enhanced the plant and soil health when compared to control and thus it could be used as a potential bio inoculant under integrated, organic and sustainable farming systems.