Effect of Salicylic Acid and Root Inoculation with P. indica on Cd Phytoremediation Efficiency and Degradation of Soil Fuel Oil in the Salinity Stress

This study was done to investigate the effect of salicylic acid (SA) and root inoculation with Piriformospora indica on Cd phytoremediation efficiency and degradation of soil fuel oil by sunflower in the salinity stress.

Treatments consisted of soil Cd pollution (0 and 5 mg Cd/kg soil), soil salinity adjusted at the EC equal to 4 and 6 dS/m, and soil pollution to fuel oil at the rates of 0%, 4%, and 8% (W/W). Foliar application of SA at the rates of 0 and 1.5 mmol/l was done 2 weeks after sunflower seedling growth in the presence and absence of P. indica. After 60 days, the plant was harvested and soil and plant Cd concentration was measured using atomic absorption spectroscopy. Soil microbial activity and degradation of soil fuel oil were also determined according to the Besaltpour et al.
method.

The greatest shoot Cd concentration belonged to the saline soil (6 dS/m) polluted with 10 mg Cd/kg soil and polluted with 8% (W/W) fuel oil, whereas the lowest was observed in the nonsaline soil polluted with 5 mg Cd/kg soil. Increasing soil salinity from 4 to 6 dS/m significantly decreased the soil microbial respiration by 8.3%. Application of 1.5 mmol/l SA significantly increased the degradation of soil fuel oil by 11.3%.

The interaction effect of P. indica and SA had a significant effect on increasing the degradation of soil fuel oil.