Study of Plant Bioelectric Potential Response Due to Photochemical Reaction and Carbon-Fixation Reaction in Photosynthetic Process

摘要

We focused on measurement of the bioelectric potential as a method of evaluating plant activities and supporting effective cultivation. In this study, we investigated the bioelectric potential response due to photochemical reactions and carbon-fixation reactions in the process of photosynthesis. First, we measured the bioelectric potential when illumination was started and stopped, under N_2 gas conditions in order to suppress the carbon-fixation reaction and respiration. It was found that the amplitude of the potential response was related to the illumination intensity and the wavelength. We considered that the amplitude of the potential response under N_2 conditions indicated the activity of the photochemical reaction. Based on this result, we investigated the potential response under room air conditions. If the carbon-fixation reaction was deactivated by a long dark period, a significant potential decrease was observed when illumination started. In contrast, if the carbon-fixation reaction remained active during a short dark period, the potential decrease was slight or none regardless of the photosynthetic rate. Therefore, we considered that this potential decrease is related to the activation of the carbon-fixation reaction. Next, we investigated the relationship between plant activity and the potential response when illumination stopped. The results showed that the amplitude of the response is related to the illumination intensity and the respiration rate. We conclude that plant activities such as photosynthesis can be evaluated in more detail by measurement of the bioelectric potential, as an application of this study.