Further Evidence on the Effects of Light on Respiration During Photosynthesis

Chlorophyll-rich and chlorophyll-deficient leaves of soybean, peperomia, and corn were compared for the effects of previous illumination on the rate of carbon dioxide evolution in the subsequent dark period. An infrared carbon dioxide analyzer was used to measure these rates. It was found that the initial rate of carbon dioxide production in the dark was affected by previous illumination in proportion to the capacity of the leaves for photosynthesis. Light accelerated carbon dioxide production in green soybean and perperomia leaves, but inhibited it in green corn leaves.Using a Geiger tube to follow changes in the concentration of C 14 O 2 around detached tobacco leaves, it was concluded that some recent product of photosynthesis was the substrate for the initial postillumination production of carbon dioxide. All above results indicated that there was a close relationship between the photosynthetic apparatus of the leaves and the production of carbon dioxide both during and immediately following a period of illumination.