Phytoremediation of Heavy Metals (Cr and Pb) Contaminated Soils by Pot Marigold (Calendula officinalis L.) with the Use of Salicylic Acid

Abstract

The pot experiment was conducted to estimate the phytoremediation potential of pot marigold (Calendula officinalis L.) an ornamental plant for the chromium and lead contaminated soils. The grown as a test plant Cr and Pb was applied as @ 0, 30 and 60 mg/kg and salicylic acid (SA) were applied as @ 0, 2 and 4 mmol/kg. The results demonstrated that the applied of SA (4 mmol/kg) significantly decreased the dry biomass yield of root and shoot i.e. Cr (3.18±0.23 and 15.84±1.28 g/pot) and Pb (3.89±0.28 and 16.14±1.28 g/pot) respectively, control pot were compared to (T6) 60 mg/kg Cr and Pb contaminated soil. The applied of SA (4 mmol/kg) significantly increased the uptake by root and shoot of pot marigold plants i.e. Cr (20.93±2.11 and 21.43±2.03 mg/kg) and Pb (22.87±1.03 and 23.09±1.14 mg/kg) respectively, in comparison to the control pot (T9) 60 mg/kg Cr and Pb contaminated soil. When SA applied, then the highest translocation factor (TF), bioaccumulation factor (BAF) and remediation factor (RF) values were recorded i.e. Cr (1.277±0.121, 0.442±0.014 mg/kg and 0.863±0.061%) and Pb (1.263±0.201, 0.500±0.041 mg/kg and 0.755±0.061%) in that order. The application of SA in Cr and Pb polluted soils considerably enhanced the uptake of these metals (Cr and Pb) though, reduced the growth and dry biomass yield of pot marigold. Therefore, SA 4 mmol/kg application may be recommended to reduce dry biomass of Calendula officinalis L. and enhance the Cr and Pb concentration in root and shoot of Calendula officinalis L. Thus, it may be concluded that salicylic acid (SA) can play a significant role in reducing the uptake of Chromium and Lead through Calendula officinalis L.