Plant inoculation with Piriformospora indica fungus and additive effects of organic and inorganic Zn fertilize on decreasing the Cd concentration of the plants cultivated in the Cd-polluted soil

Background: Nutrient deficiency in soils contaminated with heavy metals is one of the main environmental problems. This research was done to investigate the inoculation of plants with Piriformospora indica and organic and inorganic Zn sources on the Cd concentration in the plants cultivated in the Cd-polluted soil. Methods: Treatment consisted of applying organic and inorganic Zn fertilizers in the form of Zn sulfate, Zn oxide, and Zn-EDTA sources at the rates of 0, 20, and 40 kg Zn/ha in the Cd-polluted soil (0, 5, and 10 mg Cd/kg soil) under cultivation of plants inoculation with P. indica. After 90 days, plants were harvested and Zn and Cd concentrations in the plants were measured using atomic absorption spectroscopy (AAS). In addition, the ascorbate peroxidase (APX) and peroxidase (POX) enzyme activity was also measured. Results: Inoculation of plants with P. indica significantly decreased the Cd concentration of plants cultivated in the Cd-polluted soil (10 mg Cd/kg soil) by 17.1%. Furthermore, applying 40 kg Zn/ha from the Zn-EDTA source significantly decreased and increased the Cd and Zn concentrations in the plants by 12.2% and 15.1%, respectively. Although, the application efficiency of this fertilizer was lower in the soils contaminated with heavy metals. Conclusion: Plant inoculation with P. indica and using organic and inorganic Zn fertilizer had an additive effect of increasing and decreasing the Zn and Cd concentrations in plants. However, the role of the plants’ physiological characteristics and the type of soil pollutant should not be ignored.