Relationships between lipophilicity and root uptake and translocation of non-ionized chemicals by barley

The uptake by roots from solution, and subsequent translocation to shoots in barley, of two series of non‐ionised chemicals, O‐methylcarbamoyloximes and substituted phenylureas, were measured, Uptake of the chemicals by roots was greater the more lipophilic the chemical, and fell to a lower limiting value for polar chemicals. Translocation to the shoots was a passive process, and was most efficient for compounds of intermediate polarity. Both processes had reached equilibrium within 24h of treatment. The reported behaviour of many pesticides in various plant species agrees with the derived relationships, but the detailed mechanisms of these processes are unknown.