Fig. 2
Cuvette for control of leaf water content of the enclosed leaf. The cuvette A is installed on the motorized stage of an inverted fluorescence microscope B. The enclosed leaf C is attached to the transparent D lid of the cuvette with double sided tape and microscopically observed through the glass bottom made of cover slide glass. A leaf water content sensor comprised of a dual IR-LED light source E and a photo-diode (not visible) below the leaf-surface continuously tracks LWC. Its output is fed into a feedback algorithm which controls vapour pressure deficit (VPD) of the air passing over the leaf surface. Alternatively VPD can be feed-back-controlled according to the output of a air humidity sensor F. Illumination is provided by a switchable white LED light source under the control of the microscope central unit, which can be switched off for about 120 ms during fluorescence measurements