THE EFFECT OF WOUNDING THE ROOTS BY HIGH-TEMPERATURE ON THE RESPIRATION RATE OF THE SHOOT AND PROPAGATION OF ELECTRIC SIGNAL IN HORSE BEAN SEEDLINGS (VICIA-FABA L MINOR)

Damage done to horse bean roots through rapid heating to temperatures above 80 degrees C, induced the appearance of a wave of electric poten tial which reached the leaves within about 25 s. The passing wave was accompanied by stimulation of the shoot respiration which attained a m aximum rate of up to 140-160% of its initial value within 70-80 s afte r the roots had been heated. Local cooling of the stem (0 degrees C an d 2 degrees C) or freezing a section of it with liquid nitrogen, as we ll as treatment with sodium azide, inhibited the stimulation of respir ation, which seems to be a consequence of inhibition and damping of th e amplitude of the electric wave reaching the leaves. (C) 1997 Elsevie r Science Ireland Ltd.