EVALUATION OF LEAD TOLERANT PLANT GROWTH PROMOTING RHIZOBACTERIA FOR PLANT GROWTH AND PHYTOREMEDIATION IN LEAD CONTAMINATION

Abstract

The present study was conducted to evaluate five pre-characterized lead tolerant plant growth promoting rhizobacteria: Pseudomonas gessardii strain BLP141 (S2), Pseudomonas fluorescens A50 (S5), Pseudomonas syringae pv. syringae B728a (S6), Pseudomonas stutzeri strain 28a24 (S8) and Pseudomonas fluorescens strain LMG 2189 (S10), for their plant growth promotion, phytoremediation potential and physiological response on Helianthus annuus L. as test crop, exposed to different lead concentrations (300, 600 and 900 mg/kg). Crop was harvested after 30 days of sowing and data regarding growth parameters (root shoot length, root shoot fresh and dry weights), physiological attributes (photosynthetic rate, transpiration rate and substomatal CO 2 ), and lead content in root and shoot of sunflower, were recorded. Results revealed that lead contamination decreased the growth and physiological attributes of plants at all levels of lead stress; however inoculation with lead tolerant rhizobacteria reversed the toxic effect of lead on the plants and improved the growth and physiological attributes of sunflower in lead contamination, as compared to plants grown in the un-inoculated lead contaminated treatments. Among the five isolates, S2, S5 and S10 promoted more growth, improving the physiological attributes and phytoremediation potential of plants at all levels of contamination as compared to plants grown in lead stress without inoculation.