and Silvestre (1996) who observed a decrease of mineral element concentration in various plants due to anoxia.The question arises why the nutrient uptake may be inhibited by oxygen deficiency. Under anaerobic conditions the concentration of soluble carbohy-drates (glucose, fructose, sucrose) increased in shoots (Table 7) indicating that photosynthates did not limit nutrient uptake. Carbohydrate ac-cumulation generally occurs when the growth is inhibited due to various stress conditions or nutrient deficiency (Schubert 1995). Morad and Silvestre (1996) reported that under oxygen-defi-cient conditions the root cell energy pool greatly decreased. It is likely that ATP concentrations in roots decreased because of inhibition of respiration by anoxia (Drew 1988). Low ATP concentrations in roots affect the activity of the plasma membrane H+ ATPase (Schubert and Yan 1999). The low concentration of most of the analysed nutrients may be, due to anoxia, a direct consequence of the low H+ ATPase activity. The decreased alkalinity due to anoxia (Table 8) indicates, that inorganic cation uptake was more sensitive than inorganic anion uptake, which is a consequence of partial depolarization of the membrane potential at low H+ ATPase activity (Schubert and Läuchli 1988).The data of the split-root water culture experi-ment with barley indicate that anoxia in a root compartment inhibited K uptake (Figure 2), al- though the other half of the root system was sup-plied with oxygen (Table 2). Sufficient K uptake only occurred when K and oxygen were applied in the same root compartment. This result indicates that neither energy nor oxygen was translocated from one root segment to the other, and that K uptake of barley occurs if both K and oxygen are available.