Hydro-Electrochemical Integration of the Higher Plant – Basis for Electrogenic Flower Induction - Communication in Plants: Neuronal Aspects of Plant Life - page 378

Fig. 25.5. Time course of adenylate kinase ( AK ), NAD- and NADP-glyceraldehyde-3-
phosphate dehydrogenase ( GPD ) activity during darkness. C. rubrum (ecotype 184/68)
seedlings germinated in alternating light intensity and temperature for 4.5 days. Thereafter
constant 20 ◦ C, 6,000 lx fluorescent white light for 24 h followed by a dark period of varied
duration (3-h increments). The enzyme activities were measured at the end of each respec-
tive dark period. The dark period medium was either Hoagland's solution or 0.4 M glucose
in Hoagland's solution under sterile conditions. There are semicircadian oscillations with an
inverse phase relationship between photosynthetic NADP-GPD and glycolytic NAD-GPD.
Glucose feeding in darkness has no effect on NADP-GPD but stimulates the other enzyme
activities (Frosch et al. 1973)
25.6
Hydraulic-Electrochemical Integration of the Whole Plant
The integration of metabolic activity of C. rubrum plants on a hydraulic-
electrochemical level is represented by a diurnal rhythm in compound
surface-membrane potential (Fig. 25.2). Spontaneous surface-membrane
action potentials could be shown to correlate with turgor-controlled hy-
draulic growth movements of leaves and stem extension (Fig. 25.11), which
are controlled by the photoperiod. Recorded electrophysiograms can be