Entry of organic acid anions into roots.

Entry of formate, acetate, succinate, and salts of several other organic acids into barley roots takes place chiefly as ions from solutions at pH 5 to 7. The results are in accord with entry of the organic acid predominantly at pH 5 as ions through hydrophylic regions of the limiting membranes rather than by distribution of the undissociated acid to lipid-rich regions, as has previously been held. These results with a plant tissue parallel observations of others indicative of similar hydrophylic properties of membranes from animals relative to transfer of ions and small nonelectrolytes.