2) Dr. Yael Grunwald

Light intensity and quality influence photosynthesis directly but also have an indirect effect by increasing stomatal apertures and enhancing gas exchange. Consequently, in areas such as the upper canopy, a high-water demand for transpiration and temperature regulation is created.  We explored how the high light intensity and high Blue-Light (BL): Red-Light (RL) ratio in these areas, is important for controlling leaf hydraulic conductance (K_leaf) via a BL signal transduction, which results in an increase of the water permeability of the cells surrounding the vascular tissue, to support the enormous water demands. Conversely, shaded inner-canopy areas are exposed to lower radiation, and thus have lower water and cooling demands, and therefore exhibit reduced K_leaf due to diminished intensity and BL induction. Intriguingly, shaded leaves display higher water-use efficiencies (compared to upper-canopy) due to decreased transpiration and cooling requirements while the significant presence of RL supports photosynthesis.