Use of Phytohormones for Strengthening Metal(loid) Phytoextraction: Limitations and a Case Study

Abstract

Phytoextraction is a branch of phytoremediation technology in which plants are used to remove polluting substances from the environment. Among inorganic contaminants, metal(loid)s are an important problem. Of the abiotic stresses that strongly impact plant growth and healthy food, metal(loid)s in soil are an important and challenging area for scientists working on agricultural and environmental issues. Phytoextraction is basically a modifi ed "agronomic" practice where plants are used not for food production but for "cleaning" and/or rendering contaminated media less harmful. Many factors, such as the survival of plants at high-contaminant concentrations, low soil fertility conditions, and unfavorable pH values, diminish the potential of this technique. Another factor to consider is the long period of time it can take to reduce contaminants to the level of natural content or to the limit established by the laws and regulations of each country. Very recently, phytohormones were studied to resolve several phytoremediation limitations. Interesting results (presented as a case study in the second part of the chapter) were obtained from our laboratory at ISE-CNR in Pisa on the use of phytohormones as an exogenous treatment for different phytoextraction mechanisms. It was shown to counteract diffi culties plants have in combating phytotoxicity effects and to improve the technology's effi ciency.