Effect of Super Absorbent Polymer, Humic Acid and Bacteria on Physiological Traits of Annual Alfalfa (Medicago Scutellata) in Lead-Contaminated Soils

Considering the increasing environmental pollution, especially heavy metals, it is necessary to find new and inexpensive methods to clean up contaminated soils and waters. The lead is one of the most important environmental pollutants which disturbed nutrient uptake by plant. In order to investigate the potential of some biological agents in phytoremediation of lead and the absorption of nutrients by annual alfalfa in lead-contaminated soil, a factorial experiment was conducted based on completely randomized design with four replications. In the present experimental, the first factor was the heavy metal levels of lead containing lead concentrations (17.5, 417.5 and 817.5 milligram/kilogram) and the second factor was the treatment combinations including the application and non-application of superabsorbent nano polymer, humic acid and bacteria. The results showed that increased lead concentration in the soil reduced the biomass and the relative water content of the leaves and toxic in the plant. But simultaneous use of bacteria and superabsorbent which caused the absorption of water and the application of humic acid, increased the plants efficiency in food intake. The highest amount of transfer factor was observed in treatment of application of 817.5 milligram/kilogram lead and its lowest amount in the treatment of non-application of lead. Also, the use of humic acid and bacteria increased the transfer factor. The results of the present research showed that lead refining is possible by alfalfa plant, and humic acid as a chalking compound with superabsorbent and bacteria can well reduce the effects of lead toxicity in alfalfa.