MEASUREMENT OF PHOTOSYNTHETIC OXYGEN EVOLUTION WITH A NEW-TYPE OF OXYGEN SENSOR

We measured the light response curve of photosynthetic oxygen evolutio n by illuminating a leaf disc in an airtight windowed chamber. Oxygen production was measured by monitoring the quenching of luminescence of an organometallic ruthenium compound. A photodiode based chlorophyll a fluorometer was used to measure the luminescence intensity. Oxygen e volution measurements with a traditional oxygen electrode gave the sam e numerical values at different light intensities when the same leaf d isk was tested. The quality of the measurement signal of the new metho d was found to be similar to that obtained with the oxygen electrode m ethod. The new luminescence based system is more stable against electr ical disturbances than an oxygen electrode, its response to oxygen pre ssure changes is very rapid, and the new method allows the same basic equipment to be used for chlorophyll fluorescence and oxygen measureme nts.