Action Spectrum of Photosynthesis for Skeletonema costatum Obtained with Carbon-14

The quantized action spectrum of photosynthesis for Skeletonema costatum was obtained from values of photosynthetic ¹⁴CO₂ uptake at various wavelengths of light isolated “with a diffraction grating monochromator. The quantized action spectrum of photosynthesis exhibited maxima at wavelengths similar to maxima in the absorption spectrum, in vivo, of a suspension of S. costatum cells. While the ¹⁴CO₂ technique will provide an accurate action spectrum of photosynthesis for diatoms, a large number of samples is required in order to minimize sampling error.