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result(s) for
"water transport"
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What plant hydraulics can tell us about responses to climate-change droughts
Climate change exposes vegetation to unusual drought, causing declines in productivity and increased mortality. Drought responses are hard to anticipate because canopy transpiration and diffusive conductance (G) respond to drying soil and vapor pressure deficit (D) in complex ways. A growing database of hydraulic traits, combined with a parsimonious theory of tree water transport and its regulation, may improve predictions of at-risk vegetation. The theory uses the physics of flow through soil and xylem to quantify how canopy water supply declines with drought and ceases by hydraulic failure. This transpiration ‘supply function’ is used to predict a water ‘loss function’ by assuming that stomatal regulation exploits transport capacity while avoiding failure. Supply–loss theory incorporates root distribution, hydraulic redistribution, cavitation vulnerability, and cavitation reversal. The theory efficiently defines stomatal responses to D, drying soil, and hydraulic vulnerability. Driving the theory with climate predicts drought-induced loss of plant hydraulic conductance (k), canopy G, carbon assimilation, and productivity. Data lead to the ‘chronic stress hypothesis’ wherein > 60% loss of k increases mortality by multiple mechanisms. Supply–loss theory predicts the climatic conditions that push vegetation over this risk threshold. The theory's simplicity and predictive power encourage testing and application in large-scale modeling.
Journal Article
Is the amount of water transported by arbuscular mycorrhizal fungal hyphae negligible? Insights from a compartmentalized experimental study
Aims
Arbuscular mycorrhizal fungi (AMF) play a crucial role in enhancing plant resistance to drought stress by improving the plant-water relationship. However, the precise mechanism of AMF-mediated water transport to host plant roots remains elusive.
Methods
In a compartmentalized experiment comprising both plant and non-plant compartments, we employed heavy-oxygen water (
18
O-labeled) to directly trace and quantify the transport of water by AMF hyphae to alfalfa under the condition of high soil moisture (70% of the maximum field water holding capacity) and low soil moisture (40% of the maximum field water holding capacity).
Results
Our findings revealed that irrespective of soil moisture levels, hyphae entering the
18
O-labeled compartment (AM treatment) significantly enriched
18
O in alfalfa transpiration water compared to no hyphae entering the
18
O-labeled compartment (NM treatment). We calculated the direct water transport by AMF using a standard isotope mixing model, demonstrating that in high and low- moisture soil substrates, AM fungi contributed 12.32% and 17.03% of the total transpiration water, respectively.
Conclusions
These results highlight that the direct transport of water from AMF hyphae to horticulture plants should not be underestimated in comparison to plant transpiration demand. Moreover, the water contribution of AM fungal hyphae to host plants is more significant in arid soil, especially in dry soil substrate. This underscores the critical role of mycelial water transport in supporting plant survival under water-limiting conditions.
Journal Article
Experimental study on the effect of water gushing on loess metro tunnel
In the construction of metro tunnels, water gushing accidents caused by the rupture of underground pipeline often occur, and in loess area, the collapsibility of loess makes this problem more complex and difficult. To investigate the damage of metro tunnel caused by collapsible loess under the action of local dynamic water (gushing water), a model experiment was conducted based on the pipeline water gushing accident happened in the construction of metro tunnel located in loess area. Through the study of similar materials of loess and tunnel lining, the test materials and apparatus were prepared according to similarity criterion. By simulating water gushing environment in the loess stratum, this paper analyzed mechanical characteristics of tunnel (water pressure of surrounding rock, contact pressure and internal force of tunnel lining) and deformation of surrounding rock and tunnel. Furthermore, combining with the process of local collapse of loess in the model experiment, it is concluded that the formation of water transport channel is the main reason for the difference of tunnel structural response when water gushing occurs at different locations. Finally, a three-dimensional spatial model of water transport channel in loess stratum under the environment of local water gushing was established to study the rule of water transport.
Journal Article
Experimental and conceptual approaches to root water transport
Abstract Background Root water transport, which critically contributes to the plant water status and thereby plant productivity, has been the object of extensive experimental and theoretical studies. However, root systems represent an intricate assembly of cells in complex architectures, including many tissues at distinct developmental stages. Our comprehension of where and how molecular actors integrate their function in order to provide the root with its hydraulic properties is therefore still limited. Scope Based on current literature and prospective discussions, this review addresses how root water transport can be experimentally measured, what is known about the underlying molecular actors, and how elementary water transport processes are scaled up in numerical/mathematical models. Conclusions The theoretical framework and experimental procedures on root water transport that are in use today have been established a few decades ago. However, recent years have seen the appearance of new techniques and models with enhanced resolution, down to a portion of root or to the tissue level. These advances pave the way for a better comprehension of the dynamics of water uptake by roots in the soil.
Journal Article
Continuous water-water hydrogen bonding network across the rim of carbon nanotubes facilitating water transport for desalination
The development of membranes featuring carbon nanotubes (CNTs) have provided possibilities of next-generation solar desalination technologies. For solar desalination, the microstructures and interactions between the filter membrane and seawater play a crucial role in desalination performance. Understanding the mechanisms of water evaporation and ion rejection in confined pores or channels is necessary to optimize the desalting process. Here, using non-equilibrium molecular dynamics simulations, we found that continuous water-water hydrogen bonding network across the rims of CNTs is the key factor in facilitating water transport through CNTs. With the continuous hydrogen bonding network, the water flux is two times of that without the continuous hydrogen bonding network. In CNT arrays, each CNT transports water molecules and rejects salt ions independently. Based on these observations, using CNT arrays consisted with densely packed thin CNTs is the most advisable strategy for evaporation desalination, possessing high transport flux as well as maintaining high salt rejection.
Journal Article
A Relative Hydrophobicity‐Driven Framework for Liquid Water Transport in Overlapping Porous Transport Layers of Polymer Electrolyte Fuel Cells
Conventional physics‐based fuel cell models have faced limitation in explaining the through‐plane liquid water distributions observed by state‐of‐the‐art imaging techniques. To elucidate these experimental findings, we advance a temperature‐dependent phase separation model (TDPSM) framework by introducing separate liquid transport equations for each porous constituent. The proposed theoretical framework incorporates relative hydrophobicity at overlapping interfaces and employs a volume‐averaging scheme to reveal the physics underlying optical liquid visualization. A novel validation approach is proposed, enabling simultaneous prediction of through‐plane liquid profiles and conventional polarization curves with strong agreement to experimental data. Extensive numerical simulations comparing water transport scenarios with and without a microporous layer (MPL) integrate previously fragmented experimental findings on the MPL’s dual role. The study also presents water management strategies for two operating regimes: (i) low‐temperature high‐humidity (LTHH), where liquid flooding dominates, and (ii) high‐temperature low‐humidity (HTLH), where membrane dehydration presents an emerging industrial challenge. Under LTHH conditions, a hydrophobicity order of catalyst layer (CL) > MPL > gas diffusion layer (GDL) establishes an interfacial liquid pump that enables effective liquid removal. In contrast, under HTLH operation, a more hydrophobic MPL relative to the CL (MPL > CL) forms an interfacial barrier that sustains reliable membrane water retention. Overall, this theoretical framework redefines water management as a synergistic outcome of relative hydrophobic characteristics between adjacent porous layers, rather than as properties of isolated components.
Journal Article
Natural variation in PtobZIP18 confers the trade‐off between stem growth and drought tolerance in Populus
Summary Maintaining the balance between growth and drought tolerance is arguably one of the most prevalent challenges encountered by woody plants. In this study, we performed genome‐wide association studies (GWAS) of percentage loss of diameter (PLD) in the stems of 300 Populus tomentosa accessions under drought stress. Our analysis identified the bZIP transcription factor PtobZIP18 as a key regulator of xylem development in response to drought stress. PtobZIP18 directly increased the expression of PtoGATL3, PtoCESA3 and PtoDUF1635, thereby influencing wood composition and vessel density. Under well‐watered conditions, PtobZIP18 regulated the formation of significantly larger stem diameters. Conversely, PtoCIPK9 and PtoWRKY19 synergistically reduced PtobZIP18 protein levels by modulating its stability and transcription, thereby regulating water transport capacity under drought stress. Furthermore, a 110‐bp structural variation (SV) and three single‐nucleotide polymorphisms (SNPs) in the PtobZIP18 promoter divided the natural population into two haplotypes (PtobZIP18hap1 and PtobZIP18hap2). The upstream regulator PtoWRKY19 exhibited different binding affinities to these two haplotypes, resulting in differential transcriptional responses. These variations were correlated with distinct adaptive xylem structures under drought stress across three climatic regions. We further evaluated the inheritance stabilization and breeding potential of PtobZIP18hap1 and PtobZIP18hap2 by using 30 hybridization populations at two latitudinal locations. Our findings imply that PtobZIP18hap1 confers advantages for production‐related applications, whereas PtobZIP18hap2 enhances drought resistance, providing insights into tree precision breeding aimed at optimizing growth or improving drought tolerance.
Journal Article
Heating and Water Transport Behavior of Sandstones Under Microwave Irradiation
Microwave treatment has become a promising method to improve the efficiency of mechanical excavators in hard rocks. This paper conducted microwave irradiation tests on three water-bearing sandstones and analyzed the heating and water-escaping process by real-time temperature and mass measurement. Meanwhile, nuclear magnetic resonance tests were performed to investigate the water transport behavior inside the samples under microwave irradiation. The results show that the thermal behaviors are jointly governed by the water content, permeability and microwave power used. As the sample temperature increase, the contained water would firstly transport from the drying front to the surface driven by the temperature gradient. Subsequently, water began to escape from the sample with a rate determined by the permeability of the sandstone. At this stage, energy dissipation brought by water escaping would slow down the initial heating rate. Hence, the thermal cracking of the sandstones under microwave irradiation can hardly be enhanced by the existence of pore water in spite of its superior dielectric properties. Nevertheless, the vapor pressure could be large enough to burst the sample when water was heated to a high temperature.HighlightsObtained the real-time temperature and mass change under microwave irradiationInvestigated the water transport behavior in sandstones using nuclear magnetic resonance techniquesDiscussed the role water plays in microwave heating, fracturing and bursting of sandstones
Journal Article