This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via CrossRef Citing Articles via Web of Science (17) Citing Articles via Google Scholar Google Scholar Articles by Whitlow, T. H. Articles by Reichert, D. L. Search for Related Content PubMed PubMed Citation Articles by Whitlow, T. H. Articles by Reichert, D. L. Agricola Articles by Whitlow, T. H. Articles by Reichert, D. L.

Environmental and Stress Physiology

An Improved Method for Using Electrolyte Leakage to Assess Membrane Competence in Plant Tissues ¹

Urban Horticulture Institute, Cornell University, Ithaca, New York 14853, North Carolina State University Mountain Horticultural Crops Research Station, Fletcher, North Carolina 28732-9628, Department of Plant Breeding and Biometry, Cornell University, Ithaca, New York 14853

A new expression for ion leakage from plant tissue, the tissue ionic conductance (g_Ti), is compared with electrical conductivity (EC) and a commonly used damage index (I_d) to test the ability of each expression to correctly describe leakiness in two model systems representing examples of physiological processes with well-known effects on membrane permeability. In experiments in which drought-acclimated leaves were compared with nonacclimated leaves and senescing leaves were compared with nonsenescing leaves, I_d contradicted our expectation that acclimated tissue would be less leaky than nonacclimated tissue, and g_Ti and EC confirmed this expectation. In a comparison of senescing and nonsenescing tissue, I_d again contradicted our expectation that senescing tissue would be more leaky than nonsenescing, and EC and g_Ti were confirming. Using a diffusion analysis approach, we show that I_d fails to account for variation in the concentration gradient between the tissue and the bathing solution and variation in the surface area through which efflux occurs. Furthermore, because I_d is a parameter that relates treatment performance to control performance as a percentage value, it distorts the actual differences among treatments. The resulting artifacts lead to a presentation of membrane integrity which is probably incorrect. EC is a more direct measurement of net ion efflux and appears to be less vulnerable to artifact. However, because g_Ti is the only expression that explicitly includes chemical driving force and tissue surface area, it is the most reliable of the three expressions.