EFFECT OF WHITE, RED, AND BLUE LIGHT ON THE NATURE OF THE PRODUCTS OF PHOTOSYNTHESIS IN TOBACCO LEAVES

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Abstract
Detached tobacco leaves were placed singly into a photosynthesis chamber and illuminated in the presence of C14O2 with white, red, or blue light. Two kinds of experiments were carried out. In the first, the energy of the three kinds of incident light was adjusted so that the rate of CO2 uptake was the same. In the second, the energy of the three kinds of incident light was the same and the time adjusted so that an equal amount of CO2 was taken up by each leaf. At the end of photosynthesis the distribution of C14 was determined in the ethanol-soluble and-insoluble fractions and among the various compounds of the ethanol-soluble fraction that were separated by paper chromatography.No effect of wavelength of light was observed on the distribution of absorbed carbon dioxide between the ethanol-soluble and -insoluble fractions. Neither was there any evidence that red light stimulated synthesis of soluble sugars. Red light, compared with white, increased incorporation of carbon dioxide into glycine, but had no effect on serine. Blue brought about a considerable decrease in glycine and some decrease in serine.A tentative explanation is given of a mechanism by means of which the wavelength of light may affect the distribution of absorbed carbon dioxide among the various photosynthetic products.