When rain collides with plants—patterns and forces of drop impact and how leaves respond to them

Abstract

Raindrop impact on leaves is a common event which is of relevance for numerous processes, including the dispersal of pathogens and propagules, leaf wax erosion, gas exchange, leaf water absorption, and interception and storage of rainwater by canopies. The process of drop impact is complex and its outcome depends on many influential factors. The wettability of plants has been recognized as an important parameter which is itself complex and difficult to determine for leaf surfaces. Other important parameters include leaf inclination angle and the ability of leaves to respond elastically to drop impact. Different elastic motions are initiated by drop impact, including local deformation, flapping, torsion and bending, as well as “swinging” of the petiole. These elastic responses, which occur on different time scales, can affect drop impact directly or indirectly, by changing the leaf inclination. An important feature of drop impact is splashing, meaning the fragmentation of the drop with ejection of satellite droplets. This process is promoted by the kinetic energy of the drop and leaf traits. For instance, a dense trichome cover can suppress splashing. Basic drop impact patterns are presented and discussed for a number of different leaf types, as well as some exemplary mosses.

The overlooked functions of trichomes: Water absorption and metal detoxication

“…For example, it was found in some studies that trichomes could promote water condensation on the leaf surface and increase FWU (Konrad et al, 2015), whereas other studies found that trichomes are water‐repellent which is often recognized as one of the trichomes' protection functions (Brewer & Smith, 1997; Konrad et al, 2021). This is because the interactions of trichomes with water are influenced by a variety of factors, including not only the special chemical and structural properties described above, but also other factors such as trichome density, leaf properties, water form (e.g., minute or macro droplets), the pattern in which the water interacts with the trichomes (e.g., contact angle), environmental conditions and physiological situations (Roth‐Nebelsick et al, 2022).…”

“…Indeed, not all plant trichomes can absorb water. For example, the egg‐beater‐like trichomes of the floating fern ( Salvinia molesta ) are highly water‐repellent and can keep its leaves largely free from water even when the leaf is immersed in water or during rainfall events (Konrad et al, 2021; Roth‐Nebelsick et al, 2022). This again indicates that the structure and function of trichomes can be highly variable and likely evolved to assist plants to cope with a range of biotic and abiotic stress factors.…”

“…trichomes with water are influenced by a variety of factors, including not only the special chemical and structural properties described above, but also other factors such as trichome density, leaf properties, water form (e.g., minute or macro droplets), the pattern in which the water interacts with the trichomes (e.g., contact angle), environmental conditions and physiological situations(Roth-Nebelsick et al, 2022).3 | THE ROLE OF TRICHOMES IN PLANT METAL DETOXIFICATIONThe detoxification of metals by plants is a critical process for growth in environments containing elevated concentrations of metals, but much remains unknown regarding the mechanisms by which plants F I G U R E 3 Water absorption by the peltate wing-shaped trichome based upon the Bromeliaceae species(Raux et al, 2020), Capparis odoratissima(Losada et al, 2021) and Corton splendidus(Vitarelli et al, 2016). The special structure and chemical composition allow the trichomes to absorb water efficiently.…”

Molecular Dynamics Simulation on the Wettability of Nanoscale Wrinkles: High Water Adhesion of Rose Petals

“…The results were compared to those of the nanoscale strips exhibiting excellent hydrophobicity. In nature, the impact pressure of raindrops could reach 20–40 atm. , When the role of wind was included, the pressure would even rise to 198 atm . Therefore, the structures and free-energy profiles of metastable and transition states under different pressures were investigated.…”

Wind dynamics and leaf motion: Approaching the design of high-tech devices for energy harvesting for operation on plant leaves

“…The biomechanics of plant tissue under wind dynamics such as leaf fluttering has been investigated using different mechanical models ( Gonzalez-Rodriguez et al., 2016 ; De Langre, 2019 ; Geitmann et al., 2019 ; Jackson et al., 2021 ; Langer et al., 2022 ; Lauderbaugh and Holder, 2022 ; Roth-Nebelsick et al., 2022 ). Some of them consider the effect of foreign bodies like insects on leaf mechanics ( Whitney and Federle, 2013 ).…”