The Role of Rhizophagus irregularis to Alleviate Pb Absorption by Sunflower

Soil pollution with heavy metals (HM) such as Pb in human societies is one of the major environmental problems that in addition to reducing the yield and product quality, threatens to endanger sustainable agricultural production and the health of organisms. In some cases it has been observed that fungus with stabilize the toxic metals in soil and prevent from entering the root or the stabilize them in the root, prevented them from moving to the shoot. In this study, seeds of sunflower (Helianthus annuus L. cv. Farrokh Hybrid) were grown in pots containing sterilized soil and inoculated with mycorrhizal fungus, Rhizophagus irregularis. Three levels of Pb including 0, 500 and 1000 mg Pb per kg soil (Pb0, Pb1 and Pb2, respectively) as lead nitrate were added to the soil. The results showed that in high levels of Pb, dry weights as well as height of plants inoculated with R. irregularis increased significantly compared to the non-mycorrhizal plants. The Pb translocation factor and shoot Pb concentration of mycorrhizal plants were significantly lower than non-mycorrhizal ones. Pb root concentrations in Pb1 and Pb2 at mycorrhizal treatments was 0.749 and 1.445 respectively and in the non-mycorrhizal treatments was 0.492 and 1.138 milligrams per gram of dry matter, respectively.