Effects of dark-adaptation time, irradiation time and nutrient level on Fv/Fm in Prorocentrum donghaiense (Dinophyceae) during different growth phases

ABSTRACTFactors that affect maximum quantum yield values of photosystem II (Fv/Fm) during exponential and stationary phases were studied in Prorocentrum donghaiense at various dark-adaptation and culture irradiation times in three nutrient treatments. Dark-adaptation and culture-irradiation times were the main factors affecting changes in Fv/Fm during exponential growth. Fv/Fm in the three nutrient treatments generally decreased over time. Significant differences in Fv/Fm were not observed in the nutrient treatments. However, at the start of stationary phase, nutrient treatment and interaction between time and nutrient treatment became the main factors that affected Fv/Fm. Longer dark-adaptation and culture-irradiation times than in the exponential phase led to greater differences in Fv/Fm as a result of different nutrient treatments. Collectively, the factors affecting measurement of Fv/Fm differed in the two growth phases. We conclude that the effects of nutrients, dark-adaptation time, and culture-irra...