Effect of external lighting on biopotential of maize leaves caused by pulsed temperature stimulation

Abstract

Study of electrophysiological indicators of the condition and behavior of plants has become more important in the development of farming activities and the search for effective ways to improve the productivity of crops. The influence of external light on the adaptive ability of corn leaf cells to rhythmic cold stimulation was determined experimentally. The method of rhythmic cold stimulation is not adequate for the studied plants, but its application allows us to evaluate the stability of plant cells to external stimuli. The method consists in repeating irritation during the time period of less duration than the relative refractory phase, which causes a response of less than the previous amplitude. Because of this in the system there is a negative feedback that leads to stabilization of the amplitude of biopotentials that are registered. Rhythmic cold stimulation was applied to the leaf with the help of a quick-response thermostimulator. Rhythmic cold stimuli and settings of pulses were set by computer software. Cooling temperature was controlled using miniature differential thermocouple. Potentials of the leaf surface were diverted by an unpolarized macroelectrode and after a preamplifier fed to the input of the USB oscilloscope connected to the computer. Analysis of the results of experiments was performed using automated developed software. As a result, we experimentally established that rhythmic stimulation of leaves by cold leads to stabilization of responding potential. The level of stabilization depends on the frequency of cold stimuli and describes the adaptive properties of the system causing the biopotential. We found that the absence of photosynthesis when there is a deficit outdoor lighting leads to a significant increase in the average level of stabilized responses, indicating increased stability of the system to external influences. The maximum of this increase fell on the fourth day. This increase is likely to be due to the restructuring of functional ion transport through cell membranes, generating potentials registered. In the interval 4–9th days there was a significant decrease in stabilization, probably due to adaptation of plant cells to a lack of light, or depletion of ATP, which provides the active transport of ions across the cell membrane.