en تخصصي Special مقاله اصیل Original Article <div style="text-align: justify;"><span class="fontstyle0">Background: </span><span class="fontstyle2">Soil remediation is one the important problem in environmental studies. Thus, this research was conducted to evaluate the effect of organic chelates and gibberellic acid (GA</span><span class="fontstyle2" style="font-size:5pt;">3</span><span class="fontstyle2">) on the degradation of crude oil in the soil co-contaminated with Ni and crude oil under canola cultivation.</span><br> <span class="fontstyle0">Methods: </span><span class="fontstyle2">For treatments, HEDTA and NTA chelates at rates of 0 and 2.5 mmol/kg soil and foliar GA</span><span class="fontstyle2" style="font-size:5pt;">3</span><span class="fontstyle2"> (0 (GA</span><span class="fontstyle2" style="font-size:5pt;">3</span><span class="fontstyle2">(-) and 0.05 (GA</span><span class="fontstyle2" style="font-size:5pt;">3</span><span class="fontstyle2">(+) mM) were used. In addition, the soil was polluted with Ni (0 and 100 mg Ni/kg soil) and crude oil at rates of 0, 2, and 4% (W/W). The plant used in this experiment was canola. The concentration of Ni in soil and plant was measured using atomic absorption spectroscopy (AAS). The concentration of total petroleum hydrocarbon (TPH) was measured using GC-mass. The mean differences were calculated according to the least significant difference (LSD) test.</span><br> <span class="fontstyle0">Results: </span><span class="fontstyle2">The greatest degradation of crude oil belonged to the non-Ni-polluted soil under cultivation of GA</span><span class="fontstyle2" style="font-size:5pt;">3</span><span class="fontstyle2">-treated plant, while the lowest one was observed in the soil received the greatest level of HEDTA and NTA chelates. Applying 0.05 mM GA</span><span class="fontstyle2" style="font-size:5pt;">3 </span><span class="fontstyle2">foliar significantly increased the degradation of crude oil in soil and Ni in plant shoot by 12.1 and 8.3%, respectively. In addition, soil microbial respiration was also increased by 11.3%.</span><br> <span class="fontstyle0">Conclusion: </span><span class="fontstyle2">HEDTA, NTA, and GA</span><span class="fontstyle2" style="font-size:5pt;">3 </span><span class="fontstyle2">had a significant effect on the Ni phytoremediation efficiency and degradation of crude oil in soil that is a positive point in environmental pollution. However, the role of soil physico-chemical properties on the phytoremediation efficiency cannot be ignored.</span></div> Soil pollutants, Biodegradation, Environmental, Petroleum 15 22 http://ehemj.com/browse.php?a_code=A-10-1-158&slc_lang=en&sid=1 Amir Hossein Baghaie a-baghaie@iau-arak.ac.ir 10031947532846006153 10031947532846006153 Yes Corresponding author:Department of Soil Science, Arak Branch, Islamic Azad University, Arak, Iran Amir Daliri amdaliri2018@gmail.com 10031947532846006154 10031947532846006154 No Department of Soil Science, Arak Branch, Islamic Azad University, Arak, Iran