Among other detrimental effects of the heavy metal Cd2+, a decrease in the
plant content of essential mineral nutrients is known. In this study, the e
ffect of Cd2+ on different physiological activities of rice roots involved
in nutrient acquisition has been studied. Upon addition of 0.1 or 1 mM Cd2 to the experimental solution, root cell membranes depolarized in few minut
es, reaching very low Em values. This effect was transient and the initial
membrane potential recovered totally within 6-8 h. Only the highest concent
ration used had an inhibitory effect on root respiration. Significant respi
ratory inhibition appeared after 2 h of exposure to Cd2+ and lasted for at
least 4 h. In turn, membrane permeability increased in the presence of Cd2 for at least 8 h, inducing K+ efflux from the roots. The relationship betw
een these parameters and their possible involvement in lowered nutrient con
tent in Cd2+-treated plants is discussed.