A comparative study of the effects of EDTA and citric acid on soil enzyme activities and growth performances of Talinum triangulare

Abstract

Ethylene diamine tetraacetic acid (EDTA) and citric acid are two different chelants that have been used in several studies to enhance the phytoremediation process. Though numerous reports are available to prove the efficacy of these chelants toward enhancing the metal uptake and translocation, there are very few studies focusing on the minimization of hazards posed by the chelants. EDTA is an effective synthetic chelant that aids phytoremediation, whereas citric acid, an organic chelant, poses minimum level of toxicity to the soil. Application of a single chelant may be effective for pollutant removal but poses toxic symptoms on the soil as well as plants at higher concentrations. Nevertheless, a combination of two different chelants may prove to be effective both in terms of pollutant removal and safety. This may be attributed to the alleviating effect of one chelant over the other, which needs further investigation. The number of reports on the combined treatment of chelants, their overall effects on plant growth and soil enzymes are also limited. The present study was conducted to evaluate the individual as well as the combined effects of EDTA and citric acid on the soil enzyme activities and plant growth parameters on Talinum triangulare. The soil was treated with chelants, and plants were grown over this soil for 50 days. Growth parameters such as leaf count, shoot length, root length and girth were analyzed. The activity of three soil enzymes—amylase, invertase and cellulase—was examined. The study revealed the toxicity of chelants themselves when used in excess. Though it was found that 250 mg kg⁻¹ concentration of EDTA has the best performance in terms of plant growth, it has been noticed that plant growth and soil enzymes were least affected at 500 mg kg⁻¹ concentration of mixed chelants.