ISOLATION AND CHARACTERIZATION OF PHOSPHATE-SOLUBILIZING BACTERIA FROM RHIZOSPHERE SOIL

Different strains of phosphate-solubilizing bacteria (PSB) were isolated from the rhizosphere of different plants of Lahore District, Pakistan. The objective of the study was to explore the capabilities of PSB and evaluate their efficiency to enhance growth of sugarcane plants under greenhouse condition. The purified isolates were identified as Proteous vulgaris, Klebsiella pneumoniae, Enterobacter aerogenes, Burkholederi acepacia, Citrobacter freundii, Acinetobacter lwoffii, and Pseudomonas fluorescens, and the identification was based on the characteristic morphological and biochemical behavior The efficiency of different PSB isolates for phosphate solubilization was evaluated from the zones they formed on agar plates of Pickovaskaya growth medium (PVK) by solubilizing the tricalcium phosphate of the medium. The efficiency of purified PSB was evaluated from pot experiments of two different genetically modified sugarcane varieties (SCMV resistant CAMB-I and CAMB-II) under greenhouse condition for their positive role in plant growth promotion. All the six PSB enhanced the growth rate significantly over that in the non-inoculated control. A significant increase in plant height, number of leaves, root length and dry matter contents was recorded and E. aerogenes and C. freundii were found significantly superior over the rest of the isolates for all the tested parameters. The efficiency gradient of different isolates for CAMB4 and CAMB-II varieties was recorded as C. freundii> K pneumoniae> E. aerogenes> B. cepacia> A. lwoffii> P. vulgaris and E. aerogenes> C. freundii> A. lwoffii> B. cepacia> P. vulgaris, respectively. The results of this greenhouse evaluation are encouraging and need to be confirmed under field condition in combination with organic and chemical fertilizers.