SIMPLE DETERMINATION OF PHOTOSYNTHETIC EFFICIENCY AND PHOTOINHIBITIONOF DUNALIELLA-TERTIOLECTA BY SATURATING PULSE FLUORESCENCE MEASUREMENTS

Saturating pulse fluorescence measurements, well known from studies of higher plants, were applied to cultures of the chlorophyte Dunaliella tertiolecta. Photochemical and non-photochemical quenching, and the p hotochemical yield and photochemical efficiency of photosystem II, wer e determined for cultures of D. tertiolecta growing under varying ligh t intensities. Photosynthetic efficiencies appeared to correlate well with growth rates determined for the D. tertiolecta cultures. The phot ochemical yield provides a measure of photoinhibition effects. The res ults indicate that the saturating pulse fluorescence method may be suc cessfully used to determine photosynthetic characteristics of phytopla nkton. The technique is simple to apply and can be adapted for photosy nthetic measurements in situ, i.e. on phytoplankton in their natural h abitat.