MCA: Effects of unsteady wind and surface morphology on the plant transpiration

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Plants need to transport water and other substances between the roots and the shoots. Most of the water transported through tiny conduits evaporates from the leaves, which is called transpiration. The transpiration rate in plants is greatly affected by two structures near the leaf surface: stomata (i.e., small openings on the leaf surface) and a boundary layer (i.e., a thin air layer in which the diffusion process is dominant). These two structures are quite complicated and usually coupled with other physical and environmental factors. The stomata are surrounded by various microscopic structures of epidermal cells, and the boundary layer is strongly affected by wind. Therefore, the team will investigate how the stomata and the boundary layer affect the exchange of gases between leaves and the surrounding ambient air. Besides lab-based research activities, this research will contribute to providing agricultural training and individualized jobs to persons with impaired social and communication skills. The goal of the project is to understand abiotic effects on transpiration rate in plants based on physically controlled experiments and theoretical analysis. Physical experiments will control the air flow around plants, which plays a crucial role in altering the relative humidity and the boundary layer. When the air flows around a flexible leaf, the shape and size of the boundary layer are not stationary around the plant, but rather dynamical in space and time. Characterizing such dynamic changes in the boundary layer will allow greater understanding of the transpiration rate under varying conditions. Additionally, microstructures on the leaf surface affect the vapor concentration around the plant as droplets condense or evaporate. Overall, such a varying vapor flux near the stomata and variable boundary layer would affect the physiological performance of plants. Therefore, the reciprocal effects between the transpiration rate and external fluidic and surface properties should be characterized to illuminate natural plant-environment interactions.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.