Estimation of Conductivity and Conducting Area of Poplar Stems using a Radioactive Tracer

Abstract

Radioactive solution was forced through stems of poplar under known pressures. The velocity of the solution was monitored by Geiger tubes spaced along the stem, and by dividing velocity into the rate at which the solution was seen to exude from the distal end, the total cross-sectional area of the functional conduits was estimated. This amounted to 13 per cent of the cross-sectional area of the vessels. A value of 9.5±0.6 x 10–9 m4s−1N−1 was obtained for the conductivity with a range of 4.0–22.3 X 10–9 m4s−1N−1.