University Of Tehran Press Pollution 2383-451X 7 4 2021 10 01 Improving Phytoremediation Efficiency of Copper-spiked Calcareous Soils by Humic Acid Applications 871 884 84114 10.22059/poll.2021.324145.1095 EN Vahid Reza Saffari Research and Technology Institute of Plant Production, Shahid Bahonar University, Kerman, Iran Mahboub Saffari Department of Environment, Institute of Science and High Technology and Environmental Sciences, Graduate University of Advanced Technology, Kerman, Iran. Journal Article 2021 05 19 In current study, the enhanced efficiency of copper (Cu) phytoremediation potential of <em>Calendula officinalis L.</em> was investigated in a Cu-spiked calcareous soil, using foliar and soil application of humic acid. For this purpose, in a greenhouse experiment, seedlings of <em>C. officinalis</em> were transferred to Cu-spiked soils (0, 250 and 500 mg/kg) and treated separately with soil (soil drench) and foliar (spraying plant leaves) humic acid applications at different levels (0, 10, 20 μM). The humic acid treatments were applied 2 weeks after transferring plant, and eventually the various biochemical-physiological traits and phytoremediation indices of Cu in <em>C. officinalis</em> were measured at (specific) time points. According to the results, <em>C. officinalis</em> grew normally without any toxicity signs in Cu-spiked soils, however with increasing the Cu levels, the dry weight biomass decreased and antioxidant enzymes activities increased. Both foliar and soil humic acid application in Cu-spiked soils increased dry weight biomass, photosynthetic pigment contents, Cu concentration, and bioconcentration factor (BCF). Furthermore, the application of this organic substance, obviously moderated the Cu stress since the antioxidant enzymes activities reduced compared to the control. Based on the results, the obtained translocation factor (TF) and BCF values of Cu, which were >1, indicated that this plant is a Cu-hyperaccumulator, which could extract Cu via phytoextraction mechanism. Generally, the results of this study showed that, among the humic acid treatments, application of 20 μM (especially soil drench application) had the best effect on increasing Cu phytoremediation efficiency in the studied soil and it recommended to enhance the efficiency of Cu phytoremediation in calcareous soils. https://jpoll.ut.ac.ir/article_84114_7a4d7c7e61c53afbbe9ca81085db31cd.pdf