Figure 2: Schematic illustration of a typical four-point logistic curve fitted toFv /Fm temperature response measurement indicating the thermal tolerance variables extracted. Indicators extracted from the fit are temperatures at which Fv /Fm declines to 5%, 50% and 95% of the maximum Fv/Fm level expressed as T5 ,T50 and T95 , respectively. Decline width, DW expressed as T95 T5 .