SIMPLE DETERMINATION OF PHOTOSYNTHETIC EFFICIENCY AND PHOTOINHIBITION OF 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 photochemical yield and photochemical efficiency of photosystem II, were determined for cultures of D. tertiolecta growing under varying light intensities. Photosynthetic efficiencies appeared to correlate well with growth rates determined for the D. tertiolecta cultures. The photochemical yield provides a measure of photoinhibition effects. The results indicate that the saturating pulse fluorescence method may be successfully used to determine photosynthetic characteristics of phytoplankton. The technique is simple to apply and can be adapted for photosynthetic measurements in situ, i.e. on phytoplankton in their natural habitat.