The theoretical time-dependent behavior of a Münch pressure-flow system: the effect of sinusoidal time variation in sucrose loading and water potential

Abstract

Using the iterative model for the Münch pressure-flow mechanism derived by Christy and Ferrier (1973), the theoretical time-dependent behavior of the Münch pressure-flow system in a 15-m tree is computed in response to sinusoidal time variation in sucrose loading and water potential. Our calculations predict a "concentration wave" moving down the transport path of the type reported by Huber et al. (1937) in Quercus borealis L. The "waves" move with a phase velocity (= 3.5 cm min−1) greatly in excess of the velocity of the sieve-tube solution (= 0.4 cm min−1). It seems very likely that Huber et al. (1937) measured a phase velocity and erroneously interpreted it as the true solution velocity.