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 potential which reached the leaves within about 25 s. The passing wave was accompanied by stimulation of the shoot respiration which attained a maximum rate of up to 140-160% of its initial value within 70-80 s after the roots had been heated. Local cooling of the stem (0 degrees C and 2 degrees C) or freezing a section of it with liquid nitrogen, as well as treatment with sodium azide, inhibited the stimulation of respiration, which seems to be a consequence of inhibition and damping of the amplitude of the electric wave reaching the leaves. (C) 1997 Elsevier Science Ireland Ltd.