CO2 fixation adjustment mechanism explained by the chemical energy production and consumption balance in photosynthesis

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The aim of this experimental research is to understand, based on the CO2 exchange rate, the mutual adjustment mechanism between photochemical system and CO2 fixation system from the viewpoint of the sink-source balance in chemical energy produced and consumed for photosynthesis, and to obtain fundamental knowledge for increasing the energy utilization efficiency in leaf photosynthesis. Through this study, using leaves of sweet potato (Ipomoea batatas) and mungbean (Vigna radiata), the author has developed new experimental techniques and obtained some interesting results by applying the developed methods. By using the epidermis peeling technique devised here, CO2 exchange rate of the mesophyll can be measured with an assimilation chamber using a leaf without epidermis or stomatal resistance, and from the measurements, the in vivo activity and activation status of the main photosynthetic enzyme (RuBPCase/Oase) are estimated. Also to change chemical energy status in a leaf by intermittent illuminations, the rotating sector of high speed has been devised and improved. Knowledge of the photosynthetic response to intermittent illuminations can become a clue to understand the mutual adjustment mechanism in photosynthesis based on the sink-source balabce of chemical energy. Further detailed study to be made from now on may promise to give more distinctive and correct explanation on the adjustment mechanism for photosynthesis and establish physiological and genetical theory and method to increase the photosynthetic utilization efficiency.