The total amount of metals uptaken by alfalfa plants (Fig. 3b, d and
f) depends both on plant biomass and metal concentration in plant tissues. As time passed plant uptake increased, probably as the result of the
biomass increase, which varied more over time than heavy metal content. The most favourable scenario (increase both in plant biomass
and metal concentration) that will indeed result in enhanced metal
extraction by plants was the case of Cu, whose total uptake by alfalfa
roots was significantly enhanced over time and also in the presence of
P. aeruginosa.