Plant Tissue 2

Abstract

A new five-element electrical model was proposed recently (Zhang, Stout, and Willison, 1990; Zhang and Willison, 1991) to represent plant tissues. In previous studies on the relationship between electrical impedance and cold-hardiness, one of us had analysed data in relation to a simpler three-element electrical model. Here, we have re-analysed these data in relation to the more complex model. F-tests showed that the new model always fitted measured impedance spectra significantly better (P<0·005) than the earlier model. The previously reported increase in intracellular resistance during cold acclimation was found to be related to increased resistance of both the cytoplasm and vacuole In the species trial of birdsfood trefoil and alfalfa, cold acclimation was accompanied by an increase in extracellular resistance and a decrease in capacitances of both the plasma membrane and tonoplast. In the cultivar trial of birdsfoot trefoil, cold acclimation did not affect plasma membrane capacitance in Viking and extracellular resistance in both Leo and Viking. In the species and growth time trial, cold acclimation was accompanied by a decrease in plasma membrane capacitance in alfalfa but not in birdsfoot trefoil