Document Type : Research Paper
Authors
1 Department of Soil Science, Faculty of Agriculture, Razi University, Kermanshah, Iran
2 Assistant professor, Department of Soil Science, Faculty of Agriculture, Razi University
Abstract
Keywords
Main Subjects
EXTENDED ABSTRACT
Rapid industrialization and urbanization have resulted in increased emissions of toxic heavy metals entering the biosphere. Although these metals are toxic to many plants, some plants have evolved mechanisms to tolerate the toxicity and accumulateion of metals. Phytoremediation is an important method for refining heavy metals, but the main limitation is the low bioavailability of the metals. Chelating compounds, by releasing heavy metals from the soil solid phase, can increase their utake by the plants. Among heavy metals, cadmium (Cd) is recognized as highly toxic to living organisms and humans. In crop plants, the toxicity of Cd reduces uptake and translocation of nutrients and water, increases oxidative damage, disrupts plant metabolism, and inhibits plant morphology and physiology. In this research, the effects of some chelating agents on the phytoremediation of Vicia faba in calcareous soil contaminated with Cd were investigated.
To study the effects of some chelating agents on the phytoremediation of Vicia faba in calcareous soil contaminated with Cd, a factorial experiment was conducted based on a completely randomized design with three replications in the greenhouse of Razi University. The factors included Cd at four levels (0, 5, 10, and 15 mg kg-1 soil as CdCl2), and three chelating agents including ethylene di-amine tetra acetic acid (EDTA), citric acid (CA), and oxalic acid (OA), at two levels (4 and 8 mmol kg-1). At the end of vegetative growth and at the beginning of flowering stages of the plants, some growth parameters were determined and Cd concentration was measured in shoot and root of the plants. Based on Cd concentaration some parameters were determined. Data analysis was done using SPSS software and means comparison was done by Duncan's Multiple Range Test at α=0.05.
The analysis of variance showed that the intraction effects of EDTA, CA, and OAon most of the morphologica parameters of beans under Cd stress, i.e., root and aerial cadmium concentration, shoot height, root length, and shoot and root dry weight, were significant (p <0.01). The results showed that the application of chelating agents in the control soil sample (without Cd) increased plant growth parameters. Although Cd stress led to a decrease in the morphological characteristics, the use of chelating agents aggravated the decrease. The highest Cd concentration in the root and shoot (39.90 and 27 mg kg-1, respectively) was obtained at 15 mg kg-1 of Cd and 8 mmol kg-1 of EDTA, CA, and OA. The use of these chelating agents in the soil increased the Cd absorption in beans. Also, the results showed that the highest values of transfer factor (0.67) and biological accumulation factor (5.65) were obtained at the highest level of Cd pollution and 8 mmol kg-1 of chelating agents. This indicates that firstly, cadmium was mainly accumulated in the root and was less transferred to the shoot. Secondly, it shows the potential of bean in phytoremediation and Cd absorption. Also, the amounts of the mentioned factors with CA and OA were not much different from EDTA.
The results of the experiment confirmed that the use of EDTA, CA, and OA in the soil increased the Cd absorption in bean. Based on the biological accumulation factor (˃ 1) and transfer factor (˂1), bean plant has the potential of Cd stabilization at the all Cd and chelating agent levels. In general, the use of chelating agents is an effective method to increase the phytoremediation ability of beans in the calcareous soil contaminated with Cd. Between chelating agents, CA and OA are environmentally friendly agents and can be used instead of EDTA.
All authors have read and agreed to the published version of the manuscript. All authors contributed equally to the conceptualization of the article and writing of the original and subsequent drafts.
Data available on request from the authors.
The authors would like to thank all participants of the present study.
The authors avoided data fabrication, falsification, plagiarism, and misconduct.