THE BIO-ELECTRIC POTENTIALS OF PLANTS AND THEIR FUNCTIONAL SIGNIFICANCE: II. THE PATTERNS OF BIO-ELECTRIC POTENTIAL AND EXUDATION RATE IN EXCISED SUNFLOWER ROOTS AND STEMS

Abstract

Measurements of rate of exudation and also of biopotentials have been made with excised corn roots growing in vitro and with excised sunflower root–stem preparations growing in pots. Exudation cycles have been found to be controlled by factors endogenous to the living plant. Biopotential cycles correlated with the exudation cycles with maximum exudation at the time when the exudate electrode was most negative. Freshly excised green sunflower stems showed water absorption concurrently in both ends with the rates of water movement variously influenced by air speed, temperature, and light. Biopotential changes were again closely correlated with changes in water movement. The electrokinetic theory of transport will consistently account for all these observations.