Humic acid ameliorates phytoremediation, plant growth and antioxidative enzymes in forage turnip (Brassica rapa L.)

In this study, the effects of ethylenediaminetetraacetic acid (EDTA) and humic acid (HA) chelate applied to soils contaminated with heavy metals on the development, antioxidant defence system, and phytoremediation of forage turnip (Brassica rapa L.) were investigated for the first. Three doses of EDTA (E1: 5 mmol/kg, E-2: 10 mmol/kg, E-3: 15 mmol/kg) and three doses of HA (HA1: 500 mg/kg, HA(2): 1 000 mg/kg, HA(3): 2 000 mg/kg) were applied to soils contaminated with heavy metals (Cd, Pb, Zn, and Cr) in the pot. According to experiment results, HA application as chelate to the polluted soil caused a significant increase in the growth of forage turnip. Phytoremediation values of the plant for Cd heavy metal were found to be BCFs(hoot), BCFroot > 1, and translocation factor > 1. This result proved that forage turnip has Cd accumulating properties. Also, HA application caused a decrease in H2O2 (46%) and malondialdehyde (6%) levels and antioxidative enzyme activity in polluted soil. It has been concluded that humic acid improves the oxidative stress conditions in the plant and is more effective in the development and growth of the plant than EDTA, so that it can be used effectively in phytoremediation studies.