Electrical transport of endogenous mineral ions in green sapwood of Pinus sylvestris L. (Scots pine)

The relative migration of the major endogenous ions (K super(+), Ca super(2+), Mg super(2+), Na super(+), Cl super(-)) in green sapwood of Pinus sylvestris L. was measured in a modified Hittorf transference cell. The transference numbers obtained gave the fractions of the current carried by these ions when an electric field was applied across the wood samples under the conditions used. Potassium and calcium ions were always found to be the main endogenous current carriers, followed by magnesium, sodium and chloride ions. No significant differences in transference number were found between wood stored under refrigeration or in a deep freeze, nor was there any effect on prior gamma -irradiation. Fungal contamination in a few non-irradiated specimens led to lower transference numbers. Changes in moisture content from 86 to 141% produced no significant change but the results did depend on the tree from which the samples had been taken. A decrease in the length of the wood sample from 100 to 50 mm had little effect on the transference numbers of calcium ions but caused a decrease in those of potassium when larger quantities of electricity were passed. Transversely- and longitudinally-oriented wood samples, however, gave very similar results. Visual observation of the anode compartment indicated that the ions followed the path of least resistance between cathode and anode and that the current passed along the grain of the wood.