Uptake and Translocation of Diethyl Phosphoric acid Ester in Comparison to the Orthophosphate..The uptake of the diethyl phosphoric acid ester (DEP) through intact adventive roots of maize plants and its further translocation to the shoots was studied over a wide range of concentrations (0.001–50.0 mM P/L) in comparison to the orthophosphate (MP). The effect of the relative humidity (r.h.) and the metabolic inhibitor Na N3on both processes, uptake and translocation, was also investigated.At low concentrations the plants tended to retain a greater part of the MP intaked in the absorbing roots. Depression of the transpiration streaming influenced relatively the phosphate translocation to the shoots. The higher the MP‐outside‐concentration was, the greater the effect of the transpiration streaming was on its translocation. Treatment with 10‐4MNaN3inhibited MP‐accumulation but not its translocation from the treated roots.The results showed that passive processes are mainly responsible for the DEP‐uptake and translocation by the maize plants. Both processes were dependent to a great extent on the transpiration streaming.The r.h. affected the translocation patterns of both DEP and MP dissimilarly at low concentration, though, they come close to each other when their outside concentrations were increased.The results are discussed on the basis of the symplasm theory (2) and the dual mechanisms of ion
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