Coolpix s7000

For both experiments, at the end of the treatments plants were gently removed from the pots and roots were accurately cleaned up with tap water and then with deionized water. Plant roots treated with Cd were also placed 1 min in a HCl 0.1 M solution to clean up root surface from adsorbed Cd ions. Stem length, fresh and dry weight were measured.
Roots pictures for each plant were taken by the camera Nikon Coolpix S7000 fixed to the table by a plastic pole to maintain a steady distance from roots. Images were uploaded into a pc and processed by software Delta T scan (Delta T corporation, UK) to measure total root area, root length and, for the second experiment, leaf area.
At the end of second experiment, before plants harvest, leaf gas exchange parameters, such as the CO 2 assimilation, transpiration rates and stomatal conductance were measured using a portable photosynthesis system (LI 6400 XT, Licor, Nebraska, USA), with a standard 6 cm 2 leaf chamber. The CO 2 concentration in the leaf cuvette was fixed in 400 μmol mol -1 . The measurements were taken under 1000 μmol m -2 s -1 photosynthetic photon flux density. Within the leaf chamber, the average temperature was 27.0 ± 1.3 °C. Gas exchange determinations were performed between 8 and 11 h a.m.