Phytoremediation potential of rapeseed in phenanthrene-contaminated soils under different irrigation regimes and pumice levels

To evaluate the effects of irrigation regimes and pumice levels on the physiological parameters of rapeseed (Brassica napus) and phenanthrene phytoremediation efficiency, a 15-week pot experiment was conducted in the open environment of the College of Agriculture at Fasa University. Three irrigation levels, 75%, 100% and 125% of the field capacity, I1, I2 and I3, respectively, and three pumice levels, 0%, 5% and 10% w/w soil, P0, P1 and P2, respectively, were considered. The results showed that the shoot fresh weight, shoot dry weight, shoot-root ratio, root fresh weight, root dry weight, root volume, root length, root surface area and root length density in the I3P2 treatment increased by 25%, 35%, 22%, 35%, 19%, 24%, 19%, 21% and 19%, respectively, compared to the corresponding control (I2P0). A significant increase in the number of soil microorganisms (32%) and removal of phenanthrene (74%) were achieved in I3P2 compared to I2P0. According to the Pearson correlation coefficient, all physiological parameters of rapeseed had a high negative correlation with the residual phenanthrene in the soil and consequently increased its dissipation. Therefore, the rapeseed plant can be used as a practical and effective species for the phytoremediation of phenanthrene-contaminated sites.