Water transport and mixing in plants
Expected Results: Plant continuously extract water and solutes from the soil. This transport, driven by evaporation and modulated by osmotic pressure, proceeds through the plant tissues − the regular cells (cytoplasm), their membrane and walls (plasma membrane and apoplast) and vessels (xylem and phloem) − forming a complex porous structure with a hierarchy of sizes and permeabilities36.
Which path water is taking is still debated, and little is known about the dispersion and mixing of the solutes. These questions are crucial for plants but also because they connect with the more general topic of substance delivery in living tissues. The project tackles these questions by taking advantage of the unprecedented combination of experimental techniques gathered by the CoPeRMix network (index-matching, photo-bleaching, high-resolution particle tracking and dye concentration measurements see Fig. 1.2a, diffusive strip method17) that allowed recent advances in the characterization of mixing in regular porous media and sheared particulate suspensions18.
Experiments will be conducted on a model multi-scale porous medium, upscaling the root anatomy and made of empty or porous disks (cells) surrounded by different porous media (membranes and walls). It is expected that identifying the water pathways and disentangling the elementary contributions of dispersion and stretching on the mixing dynamics of the solutes in our model multi-scale porous medium will have a strong impact on the comprehension of transport and mixing in plants.
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