Comparison of the native phosphate rock and imported triple super phosphate treated with sulfur and Thiobacillus in transfering lead and Cadmium into Pistachio seedling

Several studies have shown that the use of phosphate fertilizers resulted in the transfer of heavy metals to agricultural crops. On the other hand, potential of carbonates soils in the stabilization of P have been caused of using natural modifier along with phosphate fertilizers for increasing their effectiveness. Hence, this study was carried out to investigate the effect of native phosphate rock and imported triple superphosphate treated with sulfur and Thiobacillus on the accumulation of lead and cadmium in pistachio seedling. The pot experiment was conducted as factorial based on completely randomized design with three replications including three levels of phosphate fertilizers (control (P0), 2000 mg phosphate rock per kg soil (PR) and 67 mg triple superphosphate per kg soil (TSP)), two levels of elemental sulfur (0 (S0) and 2000 mg sulfur per kg soil (S1)) and two levels inoculums (non-inoculation (T0) and Thiobacillus inoculation (T1)). Cadmium and lead concentrations in shoots and roots were measured and also cadmium and lead concentrations were analysed in both phosphate fertilizers. Results showed that cadmium contamination in the triple superphosphate was 5 times higher than phosphate rock while there are no significant differences in the concentration of lead in both of fertilizers. Application of triple superphosphate had the greatest effect on shoot cadmium concentration (10.5%) compared to the phosphate rock. Using Thiobacillus increased significantly shoot cadmium concentration (6%) and cadmium translocation factor. Application of phosphate fertilizers decreased lead concentration in shoot and the highest lead concentration was observed in the control treatment.