(99c) The Pulse of Plants

Plants give life to our planet by pulling critical reagents out of the soil from below (water and micronutrients) and out of the atmosphere from above (light and carbon dioxide). To achieve this feat, they master a wide range of fluid mechanical contexts, from flows in unsaturated porous media around their roots, through nanoconfined flows in their tissues, to turbulent air flows around their leaves. They regulate these steps in the transpiration process passively through their internal and external structure and actively through valves (stomates) that control the coupling to the atmosphere. Through each day, the flux and stress within a plant pulse due to physical and biological responses to fluctuations in sunlight, wind, temperature, and humidity in the microenvironment. This pulse of plants defines their productivity and efficiency in both natural and agricultural contexts. In this talk, I will describe our work measuring these dynamics with a microfluidic sensor that itself borrows design principles from the vascular structure of plants. I will use our efforts to model the observed dynamics to illustrate the coupling of the various flows mentioned above with the physiology of plants. I will also point toward implications for improved understanding of the biology and increased efficiency in the management of water in agriculture.