where are the dynamic hydraulic signals mediating stomatal control of transpiration and photosynthesis?
A major fraction of total plant hydraulic resistance resides in the root system and in the leaves. In addition, the xylem of roots and leaves is typically more vulnerable to drought than that of stems, causing them to embolize and refill on a daily basis. These traits imply that roots and leaves are likely to represent hydraulic bottlenecks under a range of atmospheric and soil conditions. Acclimation of hydraulic architecture involves tradeoffs between daily maximum stomatal conductances and loss of hydraulic conductivity. Rapidly reversible embolism in roots and leaves constitutes part of a hydraulic signal involved in normal daily stomatal regulation to prevent xylem tension from reaching values that could provoke embolism in stems where its reversal may not be as vigorous. These tradeoffs may limit plant responses to elevated CO2 and fertilization as well as plant water stress tolerance under elevated CO2 and fertilization. Here we propose to study the role of dynamic variations in
