Some Physiological Aspects of Copper and Zinc Tolerance in Agrostis tenuis Sibth.: Cell Elongation and Membrane Damage

Three clones of Agrostis tenuis Sibth. were studied with respect to the effects of Zn and Cu on the growth of root segments excised from the zone of cell elongation. Elongation growth in segments from a Cu-tolerant and a Zn-tolerant clone was inhibited to a lesser extent by Cu and Zn respectively than was the growth of a clone which was not tolerant to these metals. Concentrations of Cu2+ which inhibited root growth also caused leakage of K+ from the cells but toxic concentrations of Zn2+ did not induce K+ leakage. Copper induced a higher rate of K+ leakage at 25 than at 0 °C. The impllcations of these results for the site of the toxic effects of Zn and Cu and the nature of the resistance mechanisms are discussed.