Bioremediation of chromium contaminated soil using metal resistant bacteria and biogas slurry in spinach (Spinacia oleracea)

Chromium is a highly toxic and non-essential element found in environment. Due to unplanned municipal disposal, mining and industrial effluents Cr contamination is becoming a matter of increased concern, so in spite of other expensive techniques bioremediation can be used. The higher concentration of Cr (VI) in the plant root zone affects many physiological processes and consequently inhibits plant growth. Plant growth promoting rhizobacteria can convert toxic form of Cr into less toxic form. In present study, a pot experiment was conducted at wire house of Institute of Soil and Environmental Sciences, University of Agriculture, Faisalabad. Three different concentrations of chromium along with biogas slurry and bacterial strain making sixteen treatments with three replications were used. Various morphological (Plant height, fresh weight of shoots, dry weight of shoots, root length, root weight), physiological (photosynthesis, chlorophyll content, moisture content) and biochemical parameters was recorded. Results were subjected to analysis using various statistical tools. From results it was declared that combine effect of plant growth promoting bacteria and biogas slurry (BGS) level (800 kg per ha) affect positively on spinach growth at three cuttings. Moreover, percent increase in plant height and shoot weight was observed 17.7 and 9.8% respectively as compared to control. In case of chromium contamination the combined application of metal resistant bacteria and biogas slurry was excellent as compared to their individual application effects like reduction in chromium concentration in shoots was observed 47.5, 70 and 74% at chromium concentration of 20, 40 and 60 mg per kg soil chromium. Moreover, percent increase in root dry weight, root fresh weight and other growth parameters was also recorded. So it was concluded that Cr resistant bacteria and biogas slurry can be used for increasing the spinach plant growth and development under chromium polluted environment.