Water Transport in Lianas as Biological Role Models in Biomimetics
The research was aimed at identification of appropriate biological models and characterization of plant functional structures which promote water transport against gravity. The aim of this project was to develop a technical transfer of the underlying biological principles into biomimetic products with substantial hydraulic conductivity. A prototype of a fiber based system was then devised together with engineers of the ITV in Denkendorf and project partners from the textile industry. Plants are able to transport water under tension, that is, under negative pressure generated by the transpiring leaves. Water is prone to be disturbed by gas bubbles with subsequent embolism and collapse of the water column. Technical systems suffer also from this problem unless they show very small pore spaces with a low hydraulic conductivity.
Hydraulic properties of several species were studied focusing on lianas. The temperate liana Aristolochia macrophylla showes several traits that are of interest: 1) substantial tension in the water-conducting elements, 2) high flow velocities, 3) simple conduits structure, 4) ability to repair embolism, 5) high stability of the water column against embolism, 6) bubble dissolution in conduits, 7) contact angles between 20° and 30° at the conduit walls. A newly discovered strong temporal-spatial regulation of evaporation over the leaf laminae documented the coupling between hydraulic system (source) and transpiring leaves (sink). Based on these findings, technical fiber systems were devised by the project partner ITV. These fibers were able to transport water with flow driven by continuous unloading on the sink side of the fiber systems.
This project, supported by the Federal Ministry of Education and Research within the framework of BIONA, aims at improving the study of water transport inside of lianas by applying a biomimetic approach.
Water transport (yellow to red) in a cross section of a Clematis vitalba stem.