Light‐dependent Proton Excretion of Wheat (Triticum aestivum L.) and Maize (Zea mays L.) Roots

Abstract

AbstractWe investigated the change of root net proton excretion of seedlings of Triticum aestivum L. and Zea mays L. with daily variation of illumination using a multi‐channel pH‐stat system. We found an increase of net proton excretion during darkness and a drop after the beginning of illumination. Inhibition of carotenoid biosynthesis by norflurazone and photooxidation of chlorophylls did not change the periodicity or its induction. The induction of diurnal periodicity was possible with blue, green and red light. After induction the oscillation of net proton excretion continued for at least two cycles under constant light. We conclude that net H+ excretion of wheat and maize roots may be regulated by an endogenous clock or by a signal from the leaves. The nature of such a hypothetical signal remains unknown.