Figure 2: Box plot of As, Ca, Cr, Cu, Fe, Mn, Ni, S and Zn concentrations and variations in the root epidermis and the outer and inner endodermis around the Casparian strip.

The results indicate that these elements in outer endodermis have relatively higher concentrations than that in the other layers, suggesting that the Casparian strip plays a role in the elemental transport in the root system.