Chemical forms of cadmium in soil and its distribution in French marigold sub-cells in response to chelator GLDA

Abstract The use of degradable chelating agents to facilitate phytoextraction is a promising low-cost method for the remediation of heavy metal-contaminated soils. However, there are few studies on how plants and soils respond to the chelating agents. In this study, the responses of French marigold(Tagetes patula L.) and soil cadmium (Cd) to the chelator tetrasodium glutamate (GLDA) was investigated in a 180 d field trial. Five GLDA treatments (0,292.5, 585, 1170, and 2340 kg hm− 2) were carried out in a Cd-contaminated soil (0.47 mg kg− 1) under French marigold plantation. The results showed that the application of GLDA significantly increased the exchangeable Cd and cell wall Cd accumulations by 42.13% and 9.39% (p < 0.05), respectively. Furthermore, increases occurred in soil pH, as well as DOC and DTPA-Cd contents with increasing the total amount of GLDA. The composite application of GLDA (2340 kg hm− 2) with French marigold reduced the total soil Cd content by 7.59% compared with the soil background. Altogether, results of this study suggested that the application of GLDA can effectively activate soil Cd and enhance the capability of French marigold for the remediation of Cd-contaminated soils.