The Effect of Biofertilizers Application on Growth Indices of Maize (Zea mays) in Lead Contaminated Soils

In order to investigate the effect of biofertilizers on growth indices of maize (Zea mays L.) in lead-contaminated soils, a factorial experiment based on a completely randomized design with three replications was conducted in the greenhouse of soil science department at Zanjan University in 2015. Factor I included: soil contamination levels of lead (0, 50, 100, 200 and 400 mg/kg soil) and Factor ΙΙ, No inoculation (C), inoculation with soluble bacteria, Phosphate (Pseudomonas putida) (P), inoculation with Funneliformis mosseae (M), inoculation with mycorrhizal fungus Funneliformis mosseae + phosphate solubilizing bacterium (M + P), inoculation with Rhizophagus intraradices mycorrhizal (I), inoculation with mycorrhizal fungi Rhizophagus intraradices + phosphate-solubilizing bacterium (I + P).  The measured parameters were leaf chlorophyll index, plant height, lead of shoot and root, Copper and Iron of root and shoot. Inoculation of soil with mycorrhizal fungi and bacteria improved plant growth and yield indices in the absence of lead. Inoculation with mycorrhizal fungus Funneliformis mosseae + phosphate-solubilizing bacterium (I + P) increased leaf chlorophyll index 11.65% compared to the no-inoculation treatment (control). Also, biofertilizers were able to increase the amount of absorbed lead in the plant root compared to the control treatment by 61.9%. In other words, they are able to retain the absorbed lead from the soil by plant root. According to the obtained results at the critical concentration of lead (400 mg/kg soil), biofertilizers could not have a beneficial and increasing effect on chlorophyll index and plant height. However, at lower concentrations of Pb, biofertilizers can decrease the harmful and adverse effects of these heavy metals on shoot and root of plant.