Figure 9.

Representative chlorophyll fluorescence images of the relative reduction state of the plastoquinone (PQ) pool, that is, the photochemical fluorescence quenching, reflecting the fraction of open PSII reaction centers (q_p), of Arabidopsis thaliana young leaves after 5 min of illumination at 140 μmol photons m⁻² s^–1. Leaves were measured after the foliar spray with distilled water (control) (a), or 30 min (b), 90 min (c), 180 min (d), and 240 min (e) after the foliar spay with 30 mg L⁻¹ of CuZn NPs. The color code depicted at the bottom of the images ranges from values 0.0 to 1.0. The areas of interest (AOI) are shown in each image. The average q_p value of all the AOI for the whole leaf is shown.