Chrysanthemum morifolium response to PAR intensity as indicated through electrical signal

Abstract

It is well documented that higher plants respond to environmental stimuli producing electrical signals that are in practise the information carriers in intracellular and intercellular communication. Since the amplitude of the biosignal can give only indistinct information about plant reaction, helping to distinguish when plant remain in a normal or in a stimulated situation, it is unable to answer what stimuli causes plant's reaction and the electrical signal generation. In order to relate plant electric wave signals characteristics to solar radiation (400 to 1100 nm) and PAR (400 to 700 nm), measurements were performed on a single stem chrysanthemum plant. All measurements were conducted in Faraday cage in order to avoid electronic noise from external sources. The electrical signals from chrysanthemum (Chrysanthemum moriflorum) plant were detected through an advanced measuring data acquisition system, included Ag/AgCl electrodes, which were placed on plant leaves. The amplitude of the electrical signal (v), solar radiation intensity (W m-2) and PAR (μmol s -1 m-2) in leaves level as well the temperature (°C) and the humidity (%) of the air inside the Faraday cage were measured. The results revealed that electrical signal amplitude alteration related more to PAR than to incoming light intensity variation. In addition electrical signal spectrum analysis showed that a specific group of frequencies are responsible for the increase of electrical signal amplitude, occurred during plant shading.