Rapid light curves (RLCs) of each sample (dark-adapted for 20 min) were determined using the“light curve”option of a pulse amplitude-modulated fluorometer. All the chlorophyll fluorescence tests were performed during the light period. The fluorescence response to increasing actinic irradiance levels was in the range of 0–820μmol photons m−2s−1, and the exposure time at each actinic irradiance was 20 s (each separated by a 0.6-s saturatingflash). The relative electron transport rates (rETRs) were obtained from theRLCresults, and the rapid light curves were refitted using the equation published byPlatt et al. The parameters for the maximum relative electron transport rate (rETRm), efficiency of the electron transport (α), and irradiance of maximum photosynthesis (Ek) were obtained by referring to the study published by Ralph and Gade mann.The maximum quantum yield (Fv/Fm) was calculated using the following equation:Fv/Fm=(Fm−Fo) /Fm,whereFvwas the variable fluorescence calculated asFv= Fm−Fo;Fm was the maximal fluorescence in the chlorophyll fluorescence induction curve from saturating light pulse; and Fo was the minimal fluorescence from a dark-adapted alga