FIGURE 6.

Fluorescence relaxation in the dark is faster in Lepidium sativum grown at low temperature. The fluorescence value measured at 3 ms during a 700 ms saturating pulse was normalized over the maximal fluorescence to obtain the V_J parameter. This parameter was used as a proxy of the redox state of the photoactive plastoquinone pool. (A) Evolution of the V_J parameter upon sequential incubations of the sample in the dark, for the three growth conditions. The points were fitted with a local regression algorithm based on a logarithmic function to visually represent the data distribution in function of the time with a continuous error estimate (10°C, blue double dashed line, 22°C green dashed line, 30°C red continuous line). The standard error of the interpolation is shown as a gray area around the curve. (B) Evolution of the V_J parameter upon sequential incubation with far-red light exciting preferentially the photosystem I. The statistical significance of the difference between non-overlapping error areas of the interpolation was confirmed by a post hoc test (p < 0.001) (10°C, n = 10; 30°C, n = 11; 22°C, n = 16). Different X and Y axes are used in (A) and (B) to highlight the differences between the growth temperatures.