The Design of Experiment as a Tool to Model Plant Trace-Metal Bioindication Abilities

Bioindicator plants are species that have the capacity to linearly uptake some elements (metal and metalloids) from the growing substrate, thus reflecting their concentration in the soil. Many factors can influence the uptake of these elements by plants, among which the simultaneous presence of several metals, a common situation in contaminated or natural soils. A novel ap-proach that can be used to validate the bioindication ability of a species growing on a polymetallic substrate is the Design of Experiment (DoE) approach. The aim of the present study was to apply the DoE in full factorial mode to model the Cu, Cd, Pb, Zn, and Cr bioindication capacity of Polygonum aviculare used as model plant. The results showed that P. aviculare has the ability to bioindicate Cd and Cr with a linear uptake (from 0.35 to 6.66, and 0.1 to 3.4 mg kg−1 respectively) unaffected by the presence of other metals. Conversely, the uptake of Pb, Cu, and Zn is strongly influenced by the presence of all the studied metals making their concentration in plant shoot not proportional to that of the soil. In conclusion, these preliminary results con-firmed that the DoE can be used to predict the bioindicator abilities of a plant for several ele-ments at the same time and to evaluate the interactions that can be established between varia-bles in the growing medium and in the plant itself. However, more studies including other plant species are needed to confirm the effectiveness of this method.