Application of adsorption methods to determine the effect of pH and Cu-stress on the changes in the surface properties of the roots

Rye plants were grown in a nutrient solution prepa- red according to Hoagland for 2 weeks at pH 7, next for 14 days at pH 4.5 (without Cu+2) and in the presence of 20, 50, or 100 mg dm-3 copper ions. The control plants were grown continuously at pH 7. The physicochemical surface properties of the roots were exa- mined using two adsorbates – polar (water vapour) and non-polar (nitrogen). The surface properties of the roots grown at pH 4.5 without Cu+2 were apparently the same as those of controls. The roots of rye which grew in the presence of Cu+2 were characte- rized by lower (relative to controls) specific surface area values. Statistically significant differences in the size of the apparent surface area (determined by water vapour) were reported for roots in- cubated with copper ions at a concentration of 20 and 50 mg dm-3. The average water vapour adsorption energy of the root surface decreased under the stress conditions. There were no statistically significant differences for the free surface area and characteristic energy of nitrogen adsorption.