STUDIES ON THE RE-ASSIMILATION OF RESPIRATORY CO2 IN ILLUMINATED LEAVES

Abstract

Experiments were performed, using rice, barley and Hydrangea leaves, to examine the re-assimilation of respiratory ¹⁴CO₂ while photosynthesis is going on in an open air flow system. It was found that the leaves which had assimilated ¹⁴CO₂ beforehand evolved, when kept under photosynthesizing conditions, three to four tenths (variable according to plant species and external conditions) of the amount of ¹⁴CO₂ to be produced in the dark. Such an incomplete re-utilization of ¹⁴CO₂ was observed also in spinach leaf homogenate as well as in the leaves which had previously absorbed ¹⁴C-glucose. The ¹⁴CO₂ output in rice leaves was found to be accelerated by the light of high intensity. A possibility of light stimulation on the respiration was suggested.