  It has been interesting that nearly all of the ion activities that have been
analysed thus far have exhibited oscillations that are tightly coupled to
growth. Here, we present discrete Fourier transform (DFT) spectra with a finite
sampling of tip-growing cells and organs that were obtained from voltage
measurements of the elongating coleoptiles of maize in situ. The electromotive
force (EMF) oscillations (~ 0.1 {\mu}V) were measured in a simple but highly
sensitive RL circuit, in which the solenoid was initially placed at the tip of
the specimen and then was moved thus changing its position in relation to
growth (EMF can be measured first at the tip, then at the sub-apical part and
finally at the shank). The influx- and efflux-induced oscillations of
Ca$^{2+}$, along with H$^{+}$, K$^{+}$ and Cl$^{-}$ were densely sampled
(preserving the Nyquist theorem in order to 'grasp the structure' of the
pulse), the logarithmic amplitude of pulse spectrum was calculated, and the
detected frequencies, which displayed a periodic sequence of pulses, were
compared with the literature data. A band of life vital individual pulses was
obtained in a single run of the experiment, which not only allowed the
fundamental frequencies (and intensities of the processes) to be determined but
also permitted the phase relations of the various transport processes in the
plasma membrane and tonoplast to be established. A discrete frequency spectrum
(like the hydrogen spectrum in quantum physics) was achieved for a growing
plant for the first time, while all of the metabolic and enzymatic functions of
the life cell cycle were preserved using this totally non-invasive treatment.
