Effect of Applying Sunflower Residues as a Green Manure on Increasing Zn Concentration of Two Iranian Wheat Cultivars in a Pb and Cd Polluted Soil

Background: This research was investigated to evaluate effect of applying sunflower residues as a green manure on increasing zinc (Zn) concentration of two Iranian wheat cultivars in a Pb and cadmium (Cd) polluted soil. Methods: Treatments included the application of sunflower residuals grown in a Zn-polluted soil  at two levels of 0 and 8 t/ha, two wheat cultivars  in a soil contaminated with Pb (0, 400 and 800 mg Pb/kg soil) and Cd (0, 5 and 10 mg Cd/kg soil). After 7 months of the experiment. Plant Pb, Zn and Cd concentrations were measured using atomic absorption spectroscopy.  Results: The highest root and shoot Zn concentration of wheat plant was belonged to the      Back cross cultivar. Addition of 8 t/ha sunflower residues in soil without Pb and Cd pollution increased the root Zn concentration of Back Cross and Kavir  cultivars by 12 and 16%, respectively. The highest and lowest Zn translocation factor of wheat plants was belonged to Back Cross and Kavir cultivars, respectively. Conclusion: Applying sunflower residues has a significant effect on increasing plant Zn concentration and can be useful as a suitable way to increase Zn concentration of wheat grown in Zn deficient and heavy metal polluted soils.