Phyto-extraction of chromium and influence of plant growth promoting bacteria to enhance plant growth

Chromium(Cr) toxicity affectsmany physiological processes and inhibits plant growth. Plant growth promoting rhizobacteria (PGPR) have ability to improve plant health in contaminated soil as well as degrade toxic Cr. Present investigation was made to examine the role of Pseudomonas putida (ATCC 39213), to enhancing the plant growth and Cr phytoextraction. Three treatments of Cr (low; 150 ppm, medium; 250 ppm and high; 500 ppm) were applied to the E. sativa seedlings, either inoculated with Pseudomonas putida (P. putida) or un-inoculated plants. Results of this study clearly indicate that P. putida inoculation significantly increased plant growth and Cr uptake as compared to un-inoculated plants. Root and shoot length increased 33% and 42%, fresh and dry weight increased 49% and 53% as compared to un-inoculated plants, respectively. However, chlorophyll and proline contents increased 39% and 44%. Physiological parameters of growth indicate that Cr toxicity decreased the plant growth, while inoculation of P. putida overcome the inhibitory effects of Cr and increased growth under Cr stress. Cr uptake by plants was increased 38% with P. putida inoculation. Provision of Indole acetic acid, siderophore and 1-aminocyclopropane-1-carboxylate deaminase (ACCD) activity by P. putida in the growing media, which may induce the Cr uptake and plant growth under stress condition in E. sativa. The present results offer insight on plant growth promoting rhizobacteria's (PGPRs), such as P. putida, potential to enhance the plant growth by inhibiting the adverse effects of Cr in E. sativa. This study will contribute towards the environmental management of Cr-contaminated areas and enhancing plant growth under Cr stress conditions. (C) 2016 Elsevier B.V. All rights reserved.