In vivo measurement of cadmium ((115m)Cd) transport and accumulation in the stems of intact tomato plants (Lycopersicon esculentum, Mill.) : I. Long distance transport and local accumulation.

Semiconductor radiation detectors have been used to study in vivo the long-distance transport and accumulation of cadmium ((115m)Cd) in the stems of tomato plants. Long-distance transport proceeds at a speed of 0.35-0.60 m h(-1). The shape of the accumulation curve is characterized by a shoulder after about 6 h. This corresponds to the saturation of the xylem tissue. The effects of changes in the nutritional pattern have been considered as well. The cadmium content in the stem sharply decreases after a transfer of the plant to a nonlabeled solution of high ionic strength, whereas it tends to stabilize after a shift to a low ionic strength medium. These observations are explained by exchange processes between cadmium and other divalent cations.