Photosynthesis in Relation to Light and Carbon Dioxide

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Abstract
Using an optical system which furnishes a high intensity at the bottom of a Warburg manometric vessel, and varying the CO2 concn. with carbonate-bicarbonate mixtures, the rate of photosynthesis of the fresh water plant, Cabomba caro-liniana, was investigated over a large range of light intensities and CO2 concns. The data obtained are described with high precision by the equation KI= p(p2 max [long dash] p2)1/2 where p is the rate of photosynthesis at light intensity I, K is a constant which locates the curve on the I axis, and pmax is the asymptotic maximum rate of photosynthesis. This equation also describes the data of photosynthesis when CO2 concn. is substituted for I. The data obtained by other investigators on different species is shown to be consistent with the above equation, indicating a fundamental similarity in kinetic properties. The presence of a fractional exponent suggests a complex mechanism involving more than 1 light reaction.