Effect of lead and plant growth promoting rhizobacteria on activity of CAT, SOD and GPX enzymes in winter oilseed rape

The heavy elements with different levels of toxicity are continuously entering the environment and polluting it anthropologically. Fortunately, special plants have evolved the ability in absorbing and accumulating selective metal which was toxic to common plants in their aerial parts. The experiment was carried out factorially as randomized complete design in research greenhouse at agricultural and natural resources faculty, Islamic Azad University- Karaj branch in 2010. Four levels of lead Pb(NO3)2 (0, 250, 500 and 750 mg.kg-1 soil) and Five levels of bacteria (control,azotobacter, azospirillum, pseudomonas and integrated of mentioned bacteria) were used. Results showed that Interaction between lead concentrations and plant growth rhizobacteria were significant effect at 1% probability level on SOD,CAT and GPX enzymes. There were significant decrease on antioxidant enzymes with increase in lead concentration at 1% probability. In contrast There were significant increase on antioxidant enzymes with applying plant growth promoting rhizobacteria at 1% probability. Results showed that antioxidant enzymes activity increased when lead concentration increased at the time that plant growth promoting rhizobacteria were used.