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Summary: One of Sherwin Carlquist's greatest scientific legacies is how far he advanced our understanding of the structural and functional relationships within the xylem. His research was critical in illuminating the occurrence and importance of tracheids co-occurring with vessels in the xylem of some eudicots. Here, we highlight key concepts and findings from his work on these topics, and how testing has advanced with the advent of recent methods that produce spatially explicit data on embolism formation. There are three classifications of tracheids within vessel-bearing xylem: vasicentric, true, and vascular. Carlquist viewed tracheids as critical in safely transporting water. We review the literature on tracheid function, focusing on transport safety and efficiency, and discuss how the presence of tracheids might affect other xylem traits in the context of tradeoffs. Available data indicate that Carlquist was correct in his view that tracheids are resistant to embolism, and they contribute to the safe transport of sap. Tracheids provide connections (bridges) among vessels that remain sap-filled within highly embolized vessel networks and, in this role, they promote embolism tolerance. There is still much to learn, and integrating tracheids into models of sap flow, understanding their pit traits and connections, and how they affect xylem functional tradeoffs will transform our understanding of plant sap transport. Diverse xylem structural arrangements suggest many potential ways for xylem networks to function. In species containing both vessels and tracheids, the hydraulic network appears to be able to tolerate high levels of vessel embolism within seasonal environments. [ABSTRACT FROM AUTHOR]

The growth of trees is inseparable from the water transpiration in the xylem. To explore the mechanism of sap rising in the xylem, the monthly variation of the dynamic viscosity and interfacial tension of the xylem sap of different tree species and their impacting factors were analyzed. In this experiment, the dynamic viscosity and interfacial tension of the xylem sap of poplar and metasequoia were measured within one year, as well as the sap velocity of poplar. Gas chromatography–mass spectrometry and atomic absorption spectroscopy were used to detect the organic components and inorganic cations of the xylem sap of poplar and metasequoia. By analyzing the influence of organic components and the inorganic cation concentration of xylem sap on the dynamic viscosity and interfacial tension of xylem sap, this study revealed that the dynamic viscosity and the interfacial tension of poplar and metasequoia samples in different months changed in basically the same manner. However, the dynamic viscosity and the interfacial tension of the metasequoia samples were generally higher than those of the poplar samples. The dynamic viscosity of the xylem sap had an obvious exponential relationship with temperature, while the interfacial tension of the xylem sap had an inconspicuous linear relationship with temperature. In addition, disparate xylem structures of the broad-leaved tree poplar and the coniferous tree metasequoia led to different concentrations of organic components and inorganic cations in their xylem sap, which made a difference in the dynamic viscosity and interfacial tension between poplar and metasequoia samples. [ABSTRACT FROM AUTHOR]

Glyphosate is a nonselective herbicide of systemic action that inhibits the enzyme 5-enolpyruvylshikimate-3-phosphate synthase, thus compromising amino acid production and consequently the growth and development of susceptible plants. The objective of this study was to evaluate the hormetic effect of glyphosate on the morphology, physiology, and biochemistry of coffee plants. Coffee seedlings (Coffea arabica cv Catuaí Vermelho IAC-144) were transplanted into pots filled with a mixture of soil and substrate and subjected to ten doses of glyphosate: 0, 11.25, 22.5, 45, 90, 180, 360, 720, 1440, and 2880 g acid equivalent (ae) ha−1. Evaluations were performed using the morphological, physiological, and biochemical variables. Data analysis for the confirmation of hormesis occurred with the application of mathematical models. The hormetic effect of glyphosate on coffee plant morphology was determined by the variables plant height, number of leaves, leaf area, and leaf, stem, and total dry mass. Doses from 14.5 to 30 g ae ha−1 caused the highest stimulation. In the physiological analyses, the highest stimulation was observed upon CO2 assimilation, transpiration, stomatal conductance, carboxylation efficiency, intrinsic water use efficiency, electron transport rate, and photochemical efficiency of photosystem II at doses ranging from 4.4 to 55 g ae ha−1. The biochemical analyses revealed significant increases in the concentrations of quinic acid, salicylic acid, caffeic acid, and coumaric acid, with maximum stimulation at doses between 3 and 140 g ae ha−1. Thus, the application of low doses of glyphosate has positive effects on the morphology, physiology, and biochemistry of coffee plants. [ABSTRACT FROM AUTHOR]

Since the 1990s, Computational Fluid Dynamics (CFD) has allowed significant progress in the distributed climate and crop modelling in greenhouses. The quality of CFD modelling chiefly relies on its capacity to depict the dynamic interaction of the crop with airflow and the subsequent heat and mass exchanges. CFD approach combines different scales of modelling, i.e., the greenhouse and its environment with the crop canopy, with an accuracy of a few cubic centimetres corresponding to the volume of one mesh cell in the greenhouse. This modelling approach accounts for the coupling of air transfers within the crop simulated to the solid matrix of a porous medium exchanging momentum, heat, and mass with air. The sink and source terms for momentum, sensible and latent heat fluxes, and other mass exchanges are assigned to each cell of the porous medium (i.e., canopy). The local air velocity, temperature, humidity, and radiation distributions can then be calculated by solving the conservation equations together with the radiative transfer equation. The crop canopy's CO2 distributions and other plant activity parameters (such as evapotranspiration or photosynthesis) are deduced from the locally distributed climate. In this paper, the coupling of the plant activity with its local microclimate using the CFD modelling approach is described in detail. Its implementation through a User Defined Function (UDF) coupling the crop submodel to the main CFD solver is also provided. The primary studies related to the CFD modelling of crops inside greenhouses are reviewed concerning various interactions such as loss of momentum, transpiration, photosynthesis, and the characteristics of the field experiments used for validations. From this analysis, future trends of CFD developments applied to crop activity are also presented. • Mechanical and heat and mass transfers at crop level in CFD modelling. • Radiative transfers within the crop rows in CFD modelling. • Photosynthetic activity, leaf temperature and crop transpiration in CFD modelling. • Simulation of shortwave radiation inside the crop. • Simulation of the distribution of CO 2 concentration in the greenhouse. [ABSTRACT FROM AUTHOR]

Although boron (B) is essential micronutrient, higher soil B concentrations become toxic to the plants in arid and semi-arid regions of the world. Very little is known about the pH related nutrient solubility, including transpiration-mediated B uptake by plants. The effects of high B (200 μM) and low to high pH (3.0–10.0) on B toxicity, transpiration and nutrient uptake by wheat and rapeseed were studied. Plants were grown for 5 weeks under greenhouse conditions and analyzed for elements concentrations. Regardless of high B or not, low pH favored in the higher B accumulation in roots and shoots of both plant species. However, both plant species exhibited a differential B uptake pattern in roots and shoots. Both low and high pH levels in combination with high B decreased the plant biomass, transpiration, N and Mg concentrations, whereas increased the K, Ca, S, Cu, Fe, Mn and Zn concentrations. With the increase in pH 3.0–10.0, excess B decreased the Cl concentrations in wheat and rapeseed. In conclusion, low pH and high B supply enhanced the transpiration-assisted B uptake by plants although pH alone had little effects on B concentrations. Furthermore, nutritional disorder caused by high B in conjunction with low to high pH (3.0–10.0) inhibited the plant growth and transpiration. [ABSTRACT FROM AUTHOR]

The green leaf area index (LAI) is an important structural parameter that can be used for monitoring plant transpiration and carbon cycling over large spatial extents. LAI is also critical for understanding biophysical processes and predicting crop productivity. However, the retrieval of wheat green LAI based on canopy reflectance is always affected by the background material. For example, in the Yangtze River Basin of China, rice residues are typically returned to rice–wheat rotation fields. Thus the background for observing wheat canopy varies from a mixture of traditional wheat-soil components to wheat-residue or wheat-residue-soil, posing a significant challenge for accurate LAI estimation at the early stages of crop growth. Furthermore, when current vegetation indices (VIs) are used to estimate LAI, leaf chlorophyll content (LCC) and field moisture are two additional confounding factors. To resolve these issues, we propose a novel residue-soil adjusted red edge difference index (RSARE), which draws on concepts from a simple physical algorithm, i.e., linear spectral mixture analysis (LSMA). The results of field, satellite and modeling experiments demonstrate that the RSARE-LAI model is generally not sensitive to LCC, or to variations in residue-soil and traditional soil backgrounds, and estimates LAI with high accuracy ( RMSE val = 0.55, RRMSE val =20.71%). In comparison to traditional VI-LAI maps, RASRE-LAI maps are less sensitive to confounding factors associated with the background components, field moisture, LCC, and both inter-annual and geographical differences. This novel residue-soil background-resistant RSARE particularly improves the accuracy of wheat LAI estimation at low LAI levels, thus facilitating large-scale mapping of LAI in the early growing season. [ABSTRACT FROM AUTHOR]

Copyright of China Rural Water & Hydropower is the property of China Rural Water & Hydropower Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Estimating evapotranspiration (ET) has been one of the most critical research areas in agriculture because of water scarcity, the growing population, and climate change. The accurate estimation and mapping of ET are necessary for crop water management. Traditionally, researchers use water balance, soil moisture, weighing lysimeters, or an energy balance approach, such as Bowen ratio or eddy covariance towers to estimate ET. However, these ET methods are point-specific or area-weighted measurements and cannot be extended to a large scale. With the advent of satellite technology, remote sensing images became able to provide spatially distributed measurements. However, the spatial resolution of multispectral satellite images is in the range of meters, tens of meters, or hundreds of meters, which is often not enough for crops with clumped canopy structures, such as trees and vines. Unmanned aerial vehicles (UAVs) can mitigate these spatial and temporal limitations. Lightweight cameras and sensors can be mounted on the UAVs and take high-resolution images. Unlike satellite imagery, the spatial resolution of the UAV images can be at the centimeter-level. UAVs can also fly on-demand, which provides high temporal imagery. In this study, the authors examined different UAV-based approaches of ET estimation at first. Models and algorithms, such as mapping evapotranspiration at high resolution with internalized calibration (METRIC), the two-source energy balance (TSEB) model, and machine learning (ML) are analyzed and discussed herein. Second, challenges and opportunities for UAVs in ET estimation are also discussed, such as uncooled thermal camera calibration, UAV image collection, and image processing. Then, the authors share views on ET estimation with UAVs for future research and draw conclusive remarks.

Transpiration in humid tropical forests modulates the global water cycle and is a key driver of climate regulation. Yet, our understanding of how tropical trees regulate sap flux in response to climate variability remains elusive. With a progressively warming climate, atmospheric evaporative demand [i.e., vapor pressure deficit (VPD)] will be increasingly important for plant functioning, becoming the major control of plant water use in the twenty-first century. Using measurements in 34 tree species at seven sites across a precipitation gradient in the neotropics, we determined how the maximum sap flux velocity (vmax) and the VPD threshold at which vmax is reached (VPDmax) vary with precipitation regime [mean annual precipitation (MAP); seasonal drought intensity (PDRY)] and two functional traits related to foliar and wood economics spectra [leaf mass per area (LMA); wood specific gravity (WSG)]. We show that, even though vmax is highly variable within sites, it follows a negative trend in response to increasing MAP and PDRY across sites. LMA and WSG exerted little effect on vmax and VPDmax, suggesting that these widely used functional traits provide limited explanatory power of dynamic plant responses to environmental variation within hyper-diverse forests. This study demonstrates that long-term precipitation plays an important role in the sap flux response of humid tropical forests to VPD. Our findings suggest that under higher evaporative demand, trees growing in wetter environments in humid tropical regions may be subjected to reduced water exchange with the atmosphere relative to trees growing in drier climates.

Stomatal responses to humidity, soil moisture and other factors that influence plant water status are critical drivers of photosynthesis, productivity, water yield, ecohydrology and climate forcing, yet we still lack a thorough mechanistic understanding of these responses. Here I review historical and recent advances in stomatal water relations. Clear evidence now implicates a metabolically mediated response to leaf water status ('hydroactive feedback') in stomatal responses to evaporative demand and soil drought, possibly involving abscisic acid production in leaves. Other hypothetical mechanisms involving vapor and heat transport within leaves may contribute to humidity, light and temperature responses, but require further theoretical clarification and experimental validation. Variation and dynamics in hydraulic conductance, particularly within leaves, may contribute to water status responses. Continuing research to fully resolve mechanisms of stomatal responses to water status should focus on several areas: validating and quantifying the mechanism of leaf-based hydroactive feedback, identifying where in leaves water status is actively sensed, clarifying the role of leaf vapor and energy transport in humidity and temperature responses, and verifying foundational but minimally replicated results of stomatal hydromechanics across species. Clarity on these matters promises to deliver modelers with a tractable and reliable mechanistic model of stomatal responses to water status.

Modeling stomatal control is critical for predicting forest responses to the changing environment and hence the global water and carbon cycles. A trait-based stomatal control model that optimizes carbon gain while avoiding hydraulic risk has been shown to perform well in response to drought. However, the model's performance against changes in atmospheric CO2, which is rising rapidly due to human emissions, has yet to be evaluated. The present study tested the gain-risk model's ability to predict the stomatal response to CO2 concentration with potted water birch (Betula occidentalis Hook.) saplings in a growth chamber. The model's performance in predicting stomatal response to changes in atmospheric relative humidity and soil moisture was also assessed. The gain-risk model predicted the photosynthetic assimilation, transpiration rate and leaf xylem pressure under different CO2 concentrations, having a mean absolute percentage error (MAPE) of 25%. The model also predicted the responses to relative humidity and soil drought with a MAPE of 21.9% and 41.9%, respectively. Overall, the gain-risk model had an MAPE of 26.8% compared with the 37.5% MAPE obtained by a standard empirical model of stomatal conductance. Importantly, unlike empirical models, the optimization model relies on measurable physiological traits as inputs and performs well in predicting responses to novel environmental conditions without empirical corrections. Incorporating the optimization model in larger scale models has the potential for improving the simulation of water and carbon cycles.

The fluxes of energy, water, and carbon from terrestrial ecosystems influence the atmosphere. Land-atmosphere feedbacks can intensify extreme climate events like severe droughts and heatwaves because low soil moisture decreases both evaporation and plant transpiration and increases local temperature. Here, we combine data from a network of temperate and boreal eddy covariance towers, satellite data, plant trait datasets, and a mechanistic vegetation model to diagnose the controls of soil moisture feedbacks to drought. We find that climate and plant functional traits, particularly those related to maximum leaf gas exchange rate and water transport through the plant hydraulic continuum, jointly affect drought intensification. Our results reveal that plant physiological traits directly affect drought intensification and indicate that inclusion of plant hydraulic transport mechanisms in models may be critical for accurately simulating land-atmosphere feedbacks and climate extremes under climate change.

The global land surface absorbs about a third of anthropogenic emissions each year, due to the difference between two key processes: ecosystem photosynthesis and respiration. Despite the importance of these two processes, it is not possible to measure either at the ecosystem scale during the daytime. Eddy-covariance measurements are widely used as the closest 'quasi-direct' ecosystem-scale observation from which to estimate ecosystem photosynthesis and respiration. Recent research, however, suggests that current estimates may be biased by up to 25%, due to a previously unaccounted for process: the inhibition of leaf respiration in the light. Yet the extent of inhibition remains debated, and implications for estimates of ecosystem-scale respiration and photosynthesis remain unquantified. Here, we quantify an apparent inhibition of daytime ecosystem respiration across the global FLUXNET eddy-covariance network and identify a pervasive influence that varies by season and ecosystem type. We develop partitioning methods that can detect an apparent ecosystem-scale inhibition of daytime respiration and find that diurnal patterns of ecosystem respiration might be markedly different than previously thought. The results call for the re-evaluation of global terrestrial carbon cycle models and also suggest that current global estimates of photosynthesis and respiration may be biased, some on the order of magnitude of anthropogenic fossil fuel emissions.

Abstract Background Seasonal patterns of malaria cases in many parts of Africa are generally associated with rainfall, yet in the dry seasons, malaria transmission declines but does not always cease. It is important to understand what conditions support these periodic cases. Aerial moisture is thought to be important for mosquito survival and ability to forage, but its role during the dry seasons has not been well studied. During the dry season aerial moisture is minimal, but intermittent periods may arise from the transpiration of peri-domestic trees or from some other sources in the environment. These periods may provide conditions to sustain pockets of mosquitoes that become active and forage, thereby transmitting malaria. In this work, humidity along with other ecological variables that may impact malaria transmission have been examined. Methods Negative binomial regression models were used to explore the association between peri-domestic tree humidity and local malaria incidence. This was done using sensitive temperature and humidity loggers in the rural Southern Province of Zambia over three consecutive years. Additional variables including rainfall, temperature and elevation were also explored. Results A negative binomial model with no lag was found to best fit the malaria cases for the full year in the evaluated sites of the Southern Province of Zambia. Local tree and granary night-time humidity and temperature were found to be associated with local health centre-reported incidence of malaria, while rainfall and elevation did not significantly contribute to this model. A no lag and one week lag model for the dry season alone also showed a significant effect of humidity, but not temperature, elevation, or rainfall. Conclusion The study has shown that throughout the dry season, periodic conditions of sustained humidity occur that may permit foraging by resting mosquitoes, and these periods are associated with increased incidence of malaria cases. These results shed a light on conditions that impact the survival of the common malaria vector species, Anopheles arabiensis, in arid seasons and suggests how they emerge to forage when conditions permit.

Soil and air pollution caused by heavy metals and limestone dust are prevalent in urban environments and they are an alarming threat to the environment and humans. This study was designed to investigate the changes in morphological and physiological traits of three urban tree species seedlings (Bombax ceiba, Conocarpus lancifolius, and Eucalyptus camaldulensis) under the individual as well as synergetic effects of heavy metal lead (Pb) and limestone dust toxicities. The tree species were grown under controlled environmental conditions with nine treatments consisting of three levels of dust (0, 10, and 20 g) and three levels of Pb contaminated water irrigation (0, 5, and 10 mg L-1). The results depicted that the growth was maximum in T1 and minimum in T9 for all selected tree species. B. ceiba performed better under the same levels of Pb and limestone dust pollution as compared with the other two tree species. The B. ceiba tree species proved to be the most tolerant to Pb and limestone pollution by efficiently demolishing oxidative bursts by triggering SOD, POD, CAT, and proline contents under different levels of lead and dust pollution. The photosynthetic rate, stomatal conductance, evapotranspiration rate, and transpiration rate were negatively influenced in all three tree species in response to different levels of lead and dust applications. The photosynthetic rate was 1.7%, 3.1%, 7.0%, 11.03%, 16.2%, 23.8%, 24.8%, and 30.7%, and the stomatal conductance was 5%, 10.5%, 23.5%, 40%, 50.01%, 61.5%, 75%, and 90.9%, greater in T2, T3, T4, T5, T6, T7, T8, and T9 plants of B. ceiba, respectively, as compared to T1. Based on the findings, among these three tree species, B. ceiba is strongly recommended for planting in heavy metal and limestone dustpolluted areas followed by E. camaldulensis and C. lancifolius due to their better performance and efficient dust and heavy metal-scavenging capability. [ABSTRACT FROM AUTHOR]

Arabidopsis thaliana ecotypes adapted to native habitats with different daylengths, temperatures, and precipitation were grown experimentally under seven combinations of light intensity and leaf temperature to assess their acclimatory phenotypic plasticity in foliar structure and function. There were no differences among ecotypes when plants developed under moderate conditions of 400 µmol photons m−2 s−1 and 25 °C. However, in response to more extreme light or temperature regimes, ecotypes that evolved in habitats with pronounced differences in either the magnitude of changes in daylength or temperature or in precipitation level exhibited pronounced adjustments in photosynthesis and transpiration, as well as anatomical traits supporting these functions. Specifically, when grown under extremes of light intensity (100 versus 1000 µmol photons m−2 s−1) or temperature (8 °C versus 35 °C), ecotypes from sites with the greatest range of daylengths and temperature over the growing season exhibited the greatest differences in functional and structural features related to photosynthesis (light- and CO2-saturated capacity of oxygen evolution, leaf dry mass per area or thickness, phloem cells per minor vein, and water-use efficiency of CO2 uptake). On the other hand, the ecotype from the habitat with the lowest precipitation showed the greatest plasticity in features related to water transport and loss (vein density, ratio of water to sugar conduits in foliar minor veins, and transpiration rate). Despite these differences, common structure–function relationships existed across all ecotypes and growth conditions, with significant positive, linear correlations (i) between photosynthetic capacity (ranging from 10 to 110 µmol O2 m−2 s−1) and leaf dry mass per area (from 10 to 75 g m−2), leaf thickness (from 170 to 500 µm), and carbohydrate-export infrastructure (from 6 to 14 sieve elements per minor vein, from 2.5 to 8 µm2 cross-sectional area per sieve element, and from 16 to 82 µm2 cross-sectional area of sieve elements per minor vein); (ii) between transpiration rate (from 1 to 17 mmol H2O m−2 s−1) and water-transport infrastructure (from 3.5 to 8 tracheary elements per minor vein, from 13.5 to 28 µm2 cross-sectional area per tracheary element, and from 55 to 200 µm2 cross-sectional area of tracheary elements per minor vein); (iii) between the ratio of transpirational water loss to CO2 fixation (from 0.2 to 0.7 mol H2O to mmol−1 CO2) and the ratio of water to sugar conduits in minor veins (from 0.4 to 1.1 tracheary to sieve elements, from 4 to 6 µm2 cross-sectional area of tracheary to sieve elements, and from 2 to 6 µm2 cross-sectional area of tracheary elements to sieve elements per minor vein); (iv) between sugar conduits and sugar-loading cells; and (v) between water conducting and sugar conducting cells. Additionally, the proportion of water conduits to sugar conduits was greater for all ecotypes grown experimentally under warm-to-hot versus cold temperature. Thus, developmental acclimation to the growth environment included ecotype-dependent foliar structural and functional adjustments resulting in multiple common structural and functional relationships. [ABSTRACT FROM AUTHOR]

The hydrogen isotope composition of leaf wax biomarkers (δ2Hwax) is a valuable tool for reconstructing continental paleohydrology, as it serves as a proxy for the hydrogen isotope composition of precipitation (δ2Hpre). To yield robust palaeohydrological reconstructions using δ2Hwax in marine archives, it is necessary to examine the impacts of regional climate on δ2Hwax and assess the similarity between marine sedimentary δ2Hwax and the source of continental δ2Hwax. Here, we examined an aridity gradient from hyperarid to humid along the Chilean coast. We sampled sediments at the outlets of rivers draining into the Pacific, soils within catchments and marine surface sediments adjacent to the outlets of the studied rivers and analyzed the relationship between climatic variables and δ2Hwax values. We find that apparent fractionation between leaf waxes and source water is relatively constant in humid/semiarid regions (average: −121 ‰). However, it becomes less negative in hyperarid regions (average: −86 ‰) as a result of evapotranspirative processes affecting soil and leaf water 2H enrichment. We also observed that along strong aridity gradients, the 2H enrichment of δ2Hwax follows a non-linear relationship with water content and water flux variables, driven by strong soil evaporation and plant transpiration. Furthermore, our results indicated that δ2Hwax values in marine surface sediments largely reflect δ2Hwax values from the continent, confirming the robustness of marine δ2Hwax records for paleohydrological reconstructions along the Chilean margin. These findings also highlight the importance of considering the effects of hyperaridity in the interpretation of δ2Hwax values and pave the way for more quantitative paleohydrological reconstructions using δ2Hwax. [ABSTRACT FROM AUTHOR]

Although previous research has significantly enhanced our understanding of problematic and unsaturated soil behaviour and interaction with structures, there is still an urgent need to address the difficult scenarios that are met with problematic and unsaturated soils. This study examines the effects of tree water uptake at different depths and distances on the improvement of induced water uptakes caused by transpiration via mature Alstonia Angustiloba tree. This study is performed to examine the tree water uptake profile in a vegetated slope with the existence of mature Alstonia Angustiloba tree at the top and the stability of the slope during various precipitation penetration events by which the data of the tree water uptake produced within this section of the slope is recorded and implemented to evaluate the factor of safety (FOS). Slope stability analysis is further conducted to explore how plant transpiration affects slope stability. The results indicate that higher tree water uptake lead to the greatest increase of FOS of the slope up to 53% (from 2.17 to 4.57). The highest tree water uptake recorded was at the slope station with Alstonia Angustiloba tree with a depth of 0.25 m and a distance of 1.1 m from the tree. The tree water uptake utilized in this study can contribute to a carbon-free and eco-friendly approach which can be implemented globally to prevent slope failures. [ABSTRACT FROM AUTHOR]

Long-term coal mining in the Western Donbas region leads to the Samara River surface of the floodplain lowering (up to 3-7 m). The most pronounced changes were noted after 2017, especially, in 2022. It was established that covering the mine rocks with additional layers of soil, loess-like loam, and red-brown clay leads to significant inhibition of the migration of toxic salts in the contact zone with the dump due to the action of several geochemical barriers. The territory of the studied reclamation areas characterizes by insignificant species diversity. The herbal mixture should include wild plants with minimal transpiration. [ABSTRACT FROM AUTHOR]

Simple Summary: In gene expression investigations, the first crucial step is choosing appropriate housekeeping genes. However, the choice of reference genes is not absolute but relative and varies with different experimental conditions. It is vital to note that using unvalidated or unscreened internal reference genes can lead to erroneous inferences. This study was conducted on Leptocybe invasa to calculate the stability of eight housekeeping genes across various test conditions, such as sexes, somites, temperatures, diets, and pesticides. The relative expression of HSP90 at different temperature settings was evaluated to validate the results. This study aims to assist future gene expression research on this invasive species and lay the groundwork for further investigations into the gene function of this pest. Leptocybe invasa (Hymenoptera: Eulophidae) is a globally intrusive pest. Despite extensive research into the physiological responses of this pest, our understanding of the molecular mechanisms still needs to be improved. We want to accurately investigate the expression of L. invasa's target genes, so it is imperative to select fitting reference genes. In this study, eight housekeeping genes' stability (RPS30, ACTR, 18S rRNA, ACT, RPL18, GAPDH, 28S rRNA, and TUB) was tested under five different experimental conditions, including male or female adults, somites (head, thorax, and abdomen), temperatures (0 °C, 25 °C, and 40 °C), diets (starvation, clear water, 10% honey water, Eucalyptus sap), and pesticides (acetone was used as a control, imidacloprid, monosultap). Gene stability was calculated using RefFinder, which integrates four algorithms (the ∆Ct method, geNorm, NormFinder, and BestKeeper). The findings implied that ACT and ACTR were the most accurate when comparing sexes. For analyzing different somites, 28S rRNA and RPL18 were ideal; the 28S rRNA and RRS30 were perfect for analyzing at different temperatures. The combination of ACT and GAPDH helped to analyze gene expression in different diets, and GAPDH and 28S rRNA were suitable for various pesticide conditions. Overall, this research offers a complete list of reference genes from L. invasa for precise analysis of target gene expression, which can improve the trustworthiness of RT-qPCR and lay the foundation for further investigations into the gene function of this pest. [ABSTRACT FROM AUTHOR]

Aims: Rainfed rice in subSaharan Africa suffers from combined drought and phosphorus (P) deficiency stresses. Enhanced root development under water stress may counteract the physical effects of drought lowering soil P bioavailability. This study was set up to evaluate how rice genotypes respond differently to variable water stress in P deficient conditions. Methods: A greenhouse study was conducted with a full factorial combination of six genotypes, two soil P treatments (strong to moderate P deficiency) and two irrigation (W) regimes (rainfed limited and adequate). Plants were grown for 49 days and root traits were measured. Results: The overall effects of P supply on shoot weight were larger than overall effects of water supply, water stress effects were most pronounced at highest P supply because of the higher transpiration in larger plants. Reduced water supply did not enhance P stress, and the stress antagonisms were genotype dependent. There was no genotypic variation in the increased root development in response to drought that would lead to increased P uptake. Root weight and root efficiency mainly explained shoot P content across all water treatments and genotypes with marginal effects of root architectural traits. Conclusion: This study illustrates the importance of root biomass production and root efficiency under the combined stresses of water and P and corroborated the superior performance of genotypes Chhomrong Dhan and FOFIFA 172 that was found in the field. [ABSTRACT FROM AUTHOR]

Succulence is found across the world as an adaptation to water‐limited niches. The fleshy organs of succulent plants develop via enlarged photosynthetic chlorenchyma and/or achlorophyllous water storage hydrenchyma cells. The precise mechanism by which anatomical traits contribute to drought tolerance is unclear, as the effect of succulence is multifaceted. Large cells are believed to provide space for nocturnal storage of malic acid fixed by crassulacean acid metabolism (CAM), whilst also buffering water potentials by elevating hydraulic capacitance (CFT). The effect of CAM and elevated CFT on growth and water conservation have not been compared, despite the assumption that these adaptations often occur together. We assessed the relationship between succulent anatomical adaptations, CAM, and CFT, across the genus Clusia. We also simulated the effects of CAM and CFT on growth and water conservation during drought using the Photo3 model. Within Clusia leaves, CAM and CFT are independent traits: CAM requires large palisade chlorenchyma cells, whereas hydrenchyma tissue governs interspecific differences in CFT. In addition, our model suggests that CAM supersedes CFT as a means to maximise CO2 assimilation and minimise transpiration during drought. Our study challenges the assumption that CAM and CFT are mutually dependent traits within succulent leaves. Summary statement: Many succulent taxa use crassulacean acid metabolism (CAM) and elevated hydraulic capacitance (CFT) to buffer leaf water potentials. We show that CAM and elevated CFT are independent traits across the genus Clusia and that these adaptations have distinct impacts on plant performance during drought. [ABSTRACT FROM AUTHOR]

Solar steam generators based on photothermal materials are important in producing fresh water. However, conventional solar steam generators are difficult to self-adapt to the complex external environment as organisms. Herein, inspired by the plant leaf, we propose a photothermal composite based on MXene and silk to add more functionality. On one hand, the composite achieves an evaporation rate of 1.51 kg·m−2·h−1 and a conversion efficiency of 86.9% under a solar intensity of 1 kW·m−2, mimicking the water transpiration of plant leaf. On the other hand, the MXene-silk-based actuator shows a maximum bending curvature of 0.91 cm−1 under a solar intensity of 5 kW·m−2. Furthermore, an intelligent solar system is constructed utilizing the synergy of solar steam generator and actuator, which advances the research from the material level to the system level. Mimicking the behavior of plant leaf, the system can automatically open during the day to generate steam and fresh water. And at night or in bad weather, it will automatically close to prevent external pollution such as dust, achieving intelligent anti-fouling. This research will have good application prospects in less developed areas. Meanwhile, it also provides a certain reference value for exploring multi-functional photothermal devices in the future. [ABSTRACT FROM AUTHOR]

Copyright of Pesticides & Phytomedicine / Pesticidi i Fitomedicina is the property of Institute of Pesticides & Environmental Protection and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Phytoremediation is considered an effective method for indoor air pollution control. The removal rate and mechanism of benzene in air by two plants, Tradescantia zebrina Bosse and Epipremnum aureum (Linden ex André) G. S. Bunting, were investigated through fumigation experiments under the condition of plant hydroponics culturing. Results showed that the plant removal rates increased with increase in benzene concentration in air. When the benzene concentration in air was set at 432.25–1314.75 mg·m−3, the removal rates of T. zebrina and E. aureum ranged from 23.05 ± 3.07 to 57.42 ± 8.28 mg·kg–1·h–1 FW and from 18.82 ± 3.73 to 101.58 ± 21.20 mg·kg–1·h–1 FW, respectively. The removal capacity was positively related to the transpiration rate of plants, indicating that gas exchange rate could be a key factor for the evaluation of removal capacity. There existed fast reversible transport of benzene on air-shoot interface and root-solution interface. After shoot exposure to benzene for 1 h, downward transport was the dominant mechanism in the removal of benzene in air by T. zebrina, while in vivo fixation was the dominant mechanism at exposure time of 3 and 8 h. Within 1–8 h of shoot exposure time, in vivo fixation capacity was always the key factor affecting the removal rate of benzene in the air by E. aureum. Contribution ratio of in vivo fixation in the total benzene removal rate increased from 6.29 to 92.29% for T. zebrina and from 73.22 to 98.42% for E. aureum in the experimental conditions. Reactive oxygen species (ROS) burst induced by benzene exposure was responsible for the contribution ratio change of different mechanisms in the total removal rate, which also was verified by the change of activities of antioxidant enzymes (CAT, POD, and SOD). Transpiration rate and antioxidant enzyme activity could be considered parameters to evaluate the plant removal ability to benzene and to screen plants for establishment of plant-microbe combination technology. [ABSTRACT FROM AUTHOR]

Ozone is a phytotoxic pollutant that could damage the vegetation growth and lead to complicated impacts on air quality through meteorological and biogeochemical feedbacks. This study implements a semi‐empirical parameterization regarding the impacts of ozone exposure on photosynthesis rate and stomatal resistance into the Noah‐Multi‐parameterization (Noah‐MP) dynamic vegetation module of Weather Research and Forecasting with Chemistry (WRF/Chem) model. The gaseous dry deposition and biogenic emission algorithms are also coupled with Noah‐MP to enable the ozone‐vegetation coupling. This model reproduces the near‐surface meteorology, air pollutants and vegetation physiology in China, with a spatial correlation coefficient more than 0.9 and normalized mean bias from −0.19 to 0.42. The optimized model also improves the simulations of vegetation physiology (e.g., a reduction of model error by 18%–32%) and ozone dry deposition velocity. The elevated ozone damages plant photosynthesis, and decreases the national gross primary productivity (−28.85%) and leaf area index (−17.41%). The plant transpiration and surface heat flux, as well as air temperature (e.g., up to +0.16°C in summer) and other associated meteorological variables are also altered, finally contributing to 0.49 μg m−3 increase of surface ozone. Otherwise, the suppressed vegetation LAI and biogenic emissions, as well as the lower dry deposition velocity in response to the ozone‐vegetation coupling contribute to the remaining ozone changes by −1.07 μg m−3 and 1.18 μg m−3, jointly constituting the complicated ozone‐vegetation feedbacks on air quality. Our results highlight the necessity of including the ozone‐vegetation coupling in models for reliable prediction of regional climate and air quality. Plain Language Summary: Vegetation controls the land‐atmosphere carbon/water cycle and material exchange, and is thus important in global/regional climate and atmospheric environment. Chronic exposure to ozone could damage the vegetation growth and lead to complicated impacts on regional climate and air quality. This study considers the impacts of ozone exposure on plant photosynthesis and stomata using a semi‐empirical parameterization into the WRF/Chem‐Noah‐MP regional meteorology‐chemistry‐vegetation coupled model. The model well reproduces the near‐surface meteorology, air pollutants and vegetation characteristics in China, with moderate model improvements due to the optimized dynamic vegetation and dry deposition modules. The elevated ozone damages plant photosynthesis and decreases the national gross primary productivity (−28.85%) and leaf area index (−17.41%). Otherwise, the plant transpiration and surface heat flux, as well as air temperature (e.g., up to +0.16°C in summer) and other associated meteorological variables are also altered. The meteorological changes, along with the suppressed biogenic emissions from vegetation and lower dry deposition velocity due to the ozone‐vegetation damage jointly constitute the complicated ozone‐vegetation feedbacks on air quality and contribute to an average of −1.1∼1.2 μg m−3 surface ozone change. Our results highlight the necessity of including the ozone‐vegetation coupling for reliable model predictions. Key Points: The optimized model with ozone‐vegetation coupling improves the simulations of vegetation physiology and dry deposition velocity in ChinaThe O3‐damaged photosynthesis and stomatal conductance could affect regional meteorology, finally contributing to surface ozone increaseThe ozone‐vegetation coupling constitutes complex feedbacks on ozone itself by altered meteorology, biogenic emissions and dry deposition [ABSTRACT FROM AUTHOR]

Understanding root signals and their consequences on the whole plant physiology is one of the keys to tackling the water-saving challenge in agriculture. The partial root-zone drying (PRD) method is part of an ensemble of irrigation strategies that aim at improving water use efficiency. To reach this goal tools are needed for the evaluation of the root’s and soil water dynamics in time and space. In controlled laboratory conditions, using a rhizotron built for geoelectrical tomography imaging, we monitored the spatio-temporal changes in soil electrical resistivity for more than a month corresponding to six Partial Rootzone Drying (PRD) cycles. Electrical Resistivity Tomography (ERT) was complemented with Electrical Current Imaging (ECI) using plant stem-induced electrical stimulation. We demonstrated that under mild water stress conditions, it is practically impossible to spatially distinguish the PRD effects using ECI. We evidenced that the Current Source leakage depth varied during the course of the experiment but without any significant relationship to the soil water content changes or transpiration demand. On the other hand, ERT showed spatial patterns associated with irrigation and, to a lesser degree, to RWU. The interpretation of the geoelectrical imaging with respect to root activity was strengthened and correlated with indirect observations of the plant transpiration using a weight monitoring lysimeter and direct observation of the plant leaf gas exchanges. [ABSTRACT FROM AUTHOR]

Vegetation and atmosphere processes are coupled through a myriad of interactions linking plant transpiration, carbon dioxide assimilation, turbulent transport of moisture, heat and atmospheric constituents, aerosol formation, moist convection, and precipitation. Advances in our understanding are hampered by discipline barriers and challenges in understanding the role of small spatiotemporal scales. In this perspective, we propose to study the atmosphere–ecosystem interaction as a continuum by integrating leaf to regional scales (multiscale) and integrating biochemical and physical processes (multiprocesses). The challenges ahead are (1) How do clouds and canopies affect the transferring and in‐canopy penetration of radiation, thereby impacting photosynthesis and biogenic chemical transformations? (2) How is the radiative energy spatially distributed and converted into turbulent fluxes of heat, moisture, carbon, and reactive compounds? (3) How do local (leaf‐canopy‐clouds, 1 m to kilometers) biochemical and physical processes interact with regional meteorology and atmospheric composition (kilometers to 100 km)? (4) How can we integrate the feedbacks between cloud radiative effects and plant physiology to reduce uncertainties in our climate projections driven by regional warming and enhanced carbon dioxide levels? Our methodology integrates fine‐scale explicit simulations with new observational techniques to determine the role of unresolved small‐scale spatiotemporal processes in weather and climate models. [ABSTRACT FROM AUTHOR]

Potato (Solanum tuberosum L.) is the third most consumed food crop after rice and wheat in the world. It is a short-duration crop, suitable for growing in a wide range of environments, but abiotic factors can limit potato production, and drought is the main one. Therefore, managing drought stress is of utmost importance under climate change conditions. Potato as a drought-sensitive crop needs choice of suitable genotypes for dry environments. In this study, transpiration efficiency (TE), soil water conservation and drought tolerance were analysed for potato genotypes from different origins. Three glasshouse experiments under different Vapor Pressure Deficit (VPD) conditions with water-stressed (WS) and well-watered (WW) plants resulted in significantly different total amounts of transpiration among the genotypes and water supply levels. Transpiration in WS plants was the same as with WW plants up to a specific threshold "Fraction of Transpirable Soil Water" (FTSW) and then sharply decreased in response to soil drying. Genotypes showed a substantial variation in FTSW thresholds (0.19 to 0.36 FTSW) under low VPD condition, which narrowed down (0.19 to 0.29) when air humidity was lower. Furthermore, we observed hardly any relationships between TE and FTSW threshold (r = 0.125) or TE and water saving (r = 0.031). Our results provide insights into genotypic interactions with VPD on FTSW threshold and TE under dry-down conditions in potato. [ABSTRACT FROM AUTHOR]

The long‐term dynamics of the transcriptome under natural field conditions remain unclear. We conducted comprehensive gene expression analyses of rice leaves and roots grown under natural field conditions for a long period, from the tillering stage to the ripening stage. In this experiment, changes in the transcriptome were captured in relation to microclimatic parameters, particularly potential evaporation (Ep), which is a multiple meteorological factor and acts as an indicator of transpirational demand. The results indicated that many genes were regulated by changes in temperature and Ep in both leaves and roots. Furthermore, the correlation between gene expression and meteorological factors differed significantly between the vegetative and reproductive stages. Since Ep triggers transpiration, we analyzed aquaporin gene expression, which is responsible for water transport, and found that many aquaporin genes in leaves were positively correlated with Ep throughout the growth period, whereas in roots, two plasma membrane intrinsic aquaporins, PIP2;4 and PIP2;5 were strongly correlated with Ep during reproductive growth. Other genes closely related to productivity, such as those involved in nutrient absorption and photosynthesis, exhibited different responses to meteorological factors at different growth stages. The stage‐dependent shift in the microclimate response provides an important perspective on crop physiology in light of climate change. [ABSTRACT FROM AUTHOR]

Water ages in plant transpiration reveal important processes of water dynamics in soil‐plant‐atmosphere continuum, which is regulated by water variability and availability in both precipitation inputs and root zone. However, the impacts of climate patterns and rooting depth on water age dynamics in transpiration are inadequately investigated. In this study, variations in root‐zone water replenishment are estimated based on stable isotope compositions of precipitation and plant xylem water, and a piecewise linear mixing water age model is employed to quantify water ages in plant transpiration under five different climates. The results show that water ages in transpiration are very dynamic in all climates with a range between 1 and 229 days. Water replenishments in the root‐zone reveal whether and how much precipitation enters the root zone. Climate patterns control median (mean) water age in plant transpiration but modified by rooting depth. In wet climates, plants mainly rely on water source that originates from precipitation in the current month (accounting for about 60% on average of their water sources), while plants in dry climates largely rely on water source that originates from precipitation fallen on previous months/seasons. These indicate that climate has profound impacts on plant water source by regulating precipitation inputs, root zone water storage and residence time, and evapotranspiration. Despite the limitations of this study, our study provides an alternative way to reveal the precipitation partitioning in root‐zone and seasonal changes in plant water use of precipitation, which highlights different vegetation responses to water variability between climate types. Key Points: Stable isotopes reveal how precipitation is partitioned (replenishment/bypass) in the root‐zoneWater ages in plant transpiration are estimated as a function of root‐zone water replenishmentClimate patterns and rooting depth control median (mean) water age in plant transpiration [ABSTRACT FROM AUTHOR]

Copyright of Shipin Kexue/ Food Science is the property of Food Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A biodegradable seedling container was developed to minimize plastic waste in the field during post-mining land revegetation activities. Therefore, this study aims to evaluate the physiological response and growth of Samanea saman grown in a biodegradable seedling container filled with post-silica mined soil media. A factorial experimental design was used with two factors, namely (1) basic raw materials, namely recycled newspaper, compost, and cocopeat, and (2) size of raw materials, including 5 mesh, 10 mesh, and 8 mesh. The parameters measured were photosynthetic rate, leaf greenness index, transpiration rate, height, and diameter of S. saman seedlings. The results showed that the interaction between the composition and size of basic raw materials of the biodegradable seedling container significantly increased the photosynthetic rate, leaf greenness index, transpiration rate, height, and diameter of seedlings. There was also a positive correlation between the rate of photosynthetic and leaf greenness index (r = 0.838). Furthermore, the C/N ratio of the biodegradable pot varied depending on the composition of materials used. After two months, the C/N ratio decreased, indicating that decomposition processes had occurred. Analysis of the biodegradable seedling container showed that it contains less than 0.08 mg Pb kg-1, which was considered a non-toxic element for plant growth. [ABSTRACT FROM AUTHOR]

Background: Stomata are tiny pores on the leaf surface that are central to gas exchange. Stomatal number, size and aperture are key determinants of plant transpiration and photosynthesis, and variation in these traits can affect plant growth and productivity. Current methods to screen for stomatal phenotypes are tedious and not high throughput. This impedes research on stomatal biology and hinders efforts to develop resilient crops with optimised stomatal patterning. We have developed a rapid non-destructive method to phenotype stomatal traits in three crop species: wheat, rice and tomato. Results: The method consists of two steps. The first is the non-destructive capture of images of the leaf surface from plants in their growing environment using a handheld microscope; a process that only takes a few seconds compared to minutes for other methods. The second is to analyse stomatal features using a machine learning model that automatically detects, counts and measures stomatal number, size and aperture. The accuracy of the machine learning model in detecting stomata ranged from 88 to 99%, depending on the species, with a high correlation between measures of number, size and aperture using the machine learning models and by measuring them manually. The rapid method was applied to quickly identify contrasting stomatal phenotypes. Conclusions: We developed a method that combines rapid non-destructive imaging of leaf surfaces with automated image analysis. The method provides accurate data on stomatal features while significantly reducing time for data acquisition and analysis. It can be readily used to phenotype stomata in large populations in the field and in controlled environments. [ABSTRACT FROM AUTHOR]

This study aimed to clarify the effect of irrigation water amount and planting pattern on water use and yield of cotton in Northern Xinjiang. A field experiment was conducted during 2020–2021 comprising four irrigation water amounts (360, 450, 540, and 630 mm) and two planting patterns (same row spacing, R1; and wide-narrow row planting, R2). The results showed that the evapotranspiration (ET), soil evaporation (Es), and plant transpiration (T) of cotton under both planting patterns increased with the increasing irrigation amount. During the entire growth period, the annual average daily ET and T under R2 were higher than those under R1, but the annual average daily Es under R2 were lower than those under R1. The daily Es was highest between one and four days after irrigation. The Es/ET under R1 was approximately 27.45%–31.82%, and that under R2 was approximately 24.52%–28.56% under the four irrigation treatments. The relationship between the Es/ET and leaf area index was fitted based on an exponential equation (R2>0.85). The yield increased with an increase in the irrigation amount, although there was no significant difference between the yields obtained with 540 mm and 630 mm irrigation amounts. The water use efficiency (WUE) increased first and then decreased with an increase in irrigation water amount, with the highest WUE observed under the 540 mm condition and the lowest under the 630 mm condition. [ABSTRACT FROM AUTHOR]

Understanding sorghum response to water stress at different developmental stages is important for developing sorghum varieties with improved tolerance to drought. This study set out to finely characterize key agro-physiological responses and water use of sorghum subjected to different drought scenarios. A greenhouse experiment was conducted using a DroughtSpotter facility that enables real-time quantification of water use by gravimetric tracking. Four different water treatments were assessed: (i) early vegetative drought stress (DS1), (ii) DS1 plus recovery (DS1R), (iii) late vegetative drought stress (DS2), and (iv) well-watered (WW). Plant pheno-morphology and yield data were recorded. Leaf fluorescence and photosynthesis were continuously recorded throughout the experiment. Our results showed that green leaf number and plant leaf area were more affected by DS2 than DS1 and delayed plant flowering. Nevertheless, plants in DS2 were taller and produced higher stem and leaf biomass compared to DS1. No significant difference was recorded in grain yield between DS1 and DS2 but were outperformed by DS1R and WW. The transpiration and photosynthetic rates were shown to decrease at the same time as the stomatal conductance. This can therefore be assimilated to a stomatal down-regulation limiting CO2 uptake. However, the increase in intercellular CO2 concentration is likely to indicate the presence of CO2 in the substomatal cavity that was not conveyed to the carboxylation sites. This suggests a non-stomatal limitation of the photosynthesis. Moreover, the plants recovered quite well from DS1, and this was more prominent for physiological parameters than morphological ones. Globally, water use efficiency (WUE) for DS2 was higher compared to WW and DS1 treatments, confirming the growing point differentiation as a critical stage where drought stress should be avoided to ensure yield and better WUE. Adaptation responses were related to the reduction of transpiration through plant leaf area reduction, the reduction of stomatal conductance, and the increase of intercellular CO2 limiting photosynthesis. Further studies focusing on the biomarkers of stress and transcriptomic analyses are needed to provide further insight into the drought adaptation mechanisms of this line. [ABSTRACT FROM AUTHOR]

The Tigris–Euphrates dryland river basin has experienced a declining trend in terrestrial water storage (TWS) from April 2002 to June 2017. Using satellite observations and a process-based land surface model, we find that climate variations and direct human interventions explain ∼61% (−0.57 mm month−1) and ∼39% (−0.36 mm month−1) of the negative trend, respectively. We further disaggregate the effects of climate variations and find that interannual climate variability contributes substantially (−0.27 mm month−1) to the negative TWS trend, slightly greater than the decadal climate change (−0.25 mm month−1). Interannual climate variability affects TWS mainly through the nonlinear relationship between monthly TWS dynamics and aridity. Slow recovery of TWS during short wetting periods does not compensate for rapid depletion of TWS through transpiration during prolonged drying periods. Despite enhanced water stress, the dryland ecosystems show slightly enhanced resilience to water stress through greater partitioning of evapotranspiration into transpiration and weak surface "greening" effects. However, the dryland ecosystems are vulnerable to drought impacts. The basin shows straining ecosystem functioning after experiencing a severe drought event. In addition, after the onset of the drought, the dryland ecosystem becomes more sensitive to variations in climate conditions. Significance Statement: The purpose of the research is to better understand climate impacts on terrestrial water storage over dryland regions with declining water storage. In our study, we disaggregate three components of climate impacts, namely, decadal climate change, interannual variability, and intra-annual variability. We then use observational datasets and a process-based model to quantify their individual effects on water storage. We find that interannual variability is the most significant climatic contributor to the declining water storage, mainly caused by prolonged drought periods and corresponding quick drying rates due to plant transpiration. We also find that the dryland ecosystem is sensitive and vulnerable to severe drought events. This study is important because 1) it provides a framework to investigate climate impacts on water fluxes and storages, 2) it highlights the importance of vegetation dynamics on dryland hydrology, and 3) it emphasizes the negative impacts of extreme hydroclimatological events on ecosystem functioning. [ABSTRACT FROM AUTHOR]

The first symptom of aluminum (Al) toxicity is the inhibition of root growth, which has been associated with low leaf hydration, with negative consequences for leaf gas exchange including stomatal conductance (gs) observed in many plant species. Here we asked whether low leaf hydration occurs before or after the inhibition of root growth of Citrus × limonia Osbeck ('Mandarin' lime) cultivated for 60 days in nutrient solution with 0 and 1480 μM Al. The length, diameter, surface area and biomass of roots of plants exposed to Al were lower than control plants only at 30 days after treatments (DAT). Until the end of the study, estimated gs (measured by sap flow techniques) was lower than in control plants from 3 DAT, total plant transpiration (E plant) and root hydraulic conductivity (Lpr) at 7 DAT, and midday leaf water potential (Ψmd) and relative leaf water content at 15 DAT. Abscisic acid (ABA) in leaves was twofold higher in Al-exposed plants 1 DAT, and in roots a twofold higher peak was observed at 15 DAT. As ABA in leaves approached values of control plants after 15 DAT, we propose that low gs of plants exposed to Al is primarily caused by ABA, and the maintenance of low gs could be ascribed to the low Lpr from 7 DAT until the end of the study. Therefore, the low leaf hydration in 'Mandarin' lime exposed to Al does not seem to be caused by root growth inhibition or by a simple consequence of low water uptake due to a stunted root system. [ABSTRACT FROM AUTHOR]

The coupling of photosynthesis and transpiration in plant leaves forms the basis of carbon–water coupling in terrestrial ecosystems. Previous studies have attributed the coupling of leaf photosynthesis and transpiration to joint stomata control, but they lack analyses of the coupling mechanism. In this study, winter wheat (Triticum aestivum L.) was selected as a plant material on the North China Plain. Under the conditions of warming and drought stress, the photosynthetic rate (An), transpiration rate (Tr), water pressure saturation (VPD), and leaf temperature (T1) of wheat were recorded on clear days at the jointing, flowering, and grain-filling stages from 9:00 to 12:00 a.m. Then, the measured values were fitted to the simulated values obtained using the Ball–Berry and Penman–Monteith models. The results showed that the stomatal size, stomatal conductance, An, and Tr of winter wheat leaves were decreased by warming, drought stress, and their synergistic effects. Based on the Ball–Berry model, different fitting effects were observed in the treatments of adequate water supply with warming (R-g), water deficit with warming (R-d), adequate water supply without warming (N-g), and water deficit without warming (N-d). The R2 values of the R-g, R-d, N-g, and N-d treatments were 0.962, 0.958, 0.964, and 0.943, respectively. The Tr values were fitted based on the Penman–Monteith model. In the R-g, R-d, N-g, and N-d treatments, the R2 values of the R-g, R-d, N-g, and N-d treatments were 0.923, 0.849, 0.934, and 0.919, respectively. In conclusion, both warming and water deficit reduce stomatal conductance, An, Tr, and the coupling effect of photosynthesis and transpiration. [ABSTRACT FROM AUTHOR]

Purpose: The growth and carbon assimilation of plants can be promoted through increasing atmospheric CO2 concentration, which facilitates plant carbon sequestration. However, plant growth is normally limited by soil–water content and the lack of soil nutrients under elevated CO2 condition. This study explores the effects of elevated CO2 concentration on plant behaviour, with an emphasis on hydrological performance and carbon assimilation in biochar-amended soil. Methods: A tree species, Schefflera arboricola, was grown in soil with and without biochar amendment at two CO2 concentrations, 400 ppm (aCO2) and 1000 ppm (eCO2). Plant characteristics including root architecture, sap flow, and stomatal conductance were measured to reflect plant transpiration and carbon assimilation. Soil–water content and suction were measured to explore soil–plant hydraulic interactions. Results: Plant transpiration induced higher soil suction at eCO2. However, the benefits towards plant transpiration provided by eCO2 were diminished when soil suction was higher than 550 kPa. When compared with that in the same soil conditions at aCO2, plant transpiration rate and carbon assimilation at eCO2 conditions were increased by about 660% and 200%, respectively. Linear relationships between stomatal conductance and sap flow rate under different CO2 concentrations were proposed to estimate plant carbon assimilation. Conclusion: The benefits of eCO2 on plant transpiration were limited by soil–water content, which can be solved by biochar application. This study revealed the importance of examining the soil–plant hydraulic interactions when estimating plant carbon assimilation. [ABSTRACT FROM AUTHOR]

The absorption of microplastics and nanoplastics (M(N)Ps) by plants has been reported, but their uptake from natural soils that is similar to the agro-ecosystems remains unclear. Additionally, the influence of soil environment factors, such as soil moisture (SM) and soil texture (ST), on the absorption and migration of M(N)Ps from soil remains uncertain. We examined absorption of M(N)Ps of various sizes by lettuce (Lactuca sativa) in Mollisols with varying levels of SM (5, 10, 15 ml water per 2d) across different ST (23.67 % and 44.09 % sand) under controlled incubation conditions. Our results revealed high M(N)Ps absorption by lettuce from natural soil, with notable distribution, particularly in stem and even on leaf surfaces, suggesting to the potential migration path. M(N)Ps presence reduced lettuce growth across different SM and ST compared with the control group (without M(N)Ps), possibly due to the uptake of M(N)Ps. Higher SM promoted plant growth and transpiration, enhanced M(N)Ps absorption and migration, and resulted in higher concentration observed in the leaves. Moreover, an interaction between SM and ST was observed, affecting the distribution of M(N)Ps in lettuce organs. These findings underscore the significance of SM and ST as key factors affecting M(N)Ps absorption and distribution in plants. [Display omitted] • Semi-quantitative analysis of fluorescence was employed to determine M(N)Ps in lettuce. • Lettuce can absorb a great amount of M(N)Ps from the soil under natural condition. • M(N)Ps filled in whole leaf, even showed in the surface and may show potential transport into air. • Transpiration influenced by soil moisture is the key factor on M(N)Ps migration in lettuce. • Soil moisture and texture interactively influence M(N)Ps transportation in lettuce. [ABSTRACT FROM AUTHOR]

With the constant increase of the world human population, considering the rise of temperature and the frequency of heat waves predictable by climate change, a mitigation of the negative effects on human health in urban context becomes crucial. The green component of a city has a high potential on climate regulation and it becomes a key factor for the planification and sustainability of the urban environment. Incorrect pruning, especially if made by topping cut and associated whit big cuts, can significantly affect total leaf area of trees, their growth pattern as well as their microclimate amelioration capacity. The purpose of this study is to evaluate the effect of topping practice on the microclimate and on the physiology of trees. In 2004, 90 uniform diameter trees of Acer platanoides L. (Ap) and Tilia x europaea L. (Te) of the same age were planted in an experimental plot. After twelve years, when they reach 18 cm of average diameter, half of these trees were submitted to a topping operation, following a randomized block configuration, by removing 85 % of the crown to simulate a bad techniques which are alas common in city green management. The evaluation of human comfort was done using two biometeorological indices calculated from humidity and temperature, measured with a sensor under the canopy while the growth of trees was monitored with biometric measurements. Leaf gas exchanges were assessed during the two growing seasons after topping (2017–2018) with an infrared gas analyser and by measuring CO 2 assimilation as the function of internal [CO 2 ], A/Ci curves were drawn. From photosynthesis and transpiration values per unit leaf area, total CO 2 assimilation and latent heat dissipation through transpiration have been scaled to the whole plant using Big Leaf model. This study shows how topping significantly impacts the capacity of trees to ameliorate the microclimate. Biometeorological indices showed higher values below topped trees, especially in the hottest months. Despite a temporary increase of transpiration, the energy dissipated by topped trees was significantly lower, due to the smaller total leaf area. Topped trees showed an average value of latent heat dissipated by the hole tree 73,5 % lower in Te and 81,1 % in Ap. Topped trees showed different growth patterns, with higher investment in crown growth at the cost of stem enlargement. This strong crown growth reaction is due principally to adventitious watersprouts and root suckers, with higher average leaf area compared to unpruned trees. In the two years after topping, both species showed some level of compensatory photosynthesis, as well as higher stomatal conductance, chlorophyll content and mesophyll conductance to CO 2. Even considering this temporary photosynthetic increase, due to the large amount of surface removed, topping caused a loss in the total CO 2 assimilation. These results show how a correct management is necessary to assure an effective and efficient microclimate improvement. The maintenance of apical control and apical dominance are key issues to preserve a healthy tree structure, as well as the long-term efficiency of the photosynthetic apparatus. [ABSTRACT FROM AUTHOR]

Rooftop Mitigation Strategies (RMSs) have garnered global recognition as effective measures for mitigating urban thermal environments. However, the cooling effectiveness of Green Roof (GR) and Cool Roof (CR) remains a subject of ongoing debate, especially when considered within diverse climatic contexts. This study conducted RMSs observation experiments within the subtropical urban landscape of Guangzhou, China, to assess the cooling potential of these strategies during both normal weather conditions and heatwaves. Our experiments identified a critical temperature threshold that influences the cooling potential of GR, a phenomenon rooted in vegetation transpiration. Below 33 °C, transpiration gradually intensifies, resulting in a noticeable cooling effect. However, as temperatures exceed this threshold, transpiration diminishes. Coupled with the aerodynamic drag imposed by vegetation leaves on wind flow, this complex dynamic leads to a temperature increase at heights ranging from 0.3 m to 0.6 m above the roof. Given the subtropical climate's characteristics of high temperatures and humidity, prudent consideration is warranted when selecting appropriate mitigation strategies. In this context, our observations suggest that CR may be a more cost-effective and potentially more efficacious choice due to their lower costs and substantial cooling potential. Our research provides a significant contribution to the reevaluation of RMSs' cooling potential and its role in reducing urban energy consumption and lowering building carbon emissions. • Green roofs with mixed plants have a more significant cooling effect. • Heatwave weather leads to the failure of green roof cooling. • Plant transpiration and wind resistance cause near-surface warming during heatwaves. • Cool roof is an effective cooling strategy in subtropical climates. [ABSTRACT FROM AUTHOR]

• The isotopic measurement of evapotranspiration vapor by combinating in-situ chamber and Keeling plot model. • The 35 % of precipitation originated from recycled moisture. • The plant water source δD offset could be a potential cause for overestimation of moisture recycling. Terrestrial moisture recycling is an essential hydrological component and a significant source of the atmosphere's humidity budget in arid and semi-arid inland regions. Investigations on moisture recycling using the stable hydrogen and oxygen isotopes is currently a focal point in hydrologic research. However, the direct quantification of recycling ratio based on isotopic composition of evapotranspiration vapor is lacking. So, this causes challenges to compare studies, based in the same region and time period but with different methodologies. In this study, we measured the isotopic compositions of evapotranspiration vapor (δ18O ET /δD ET) from June to September 2018 in an alpine meadow ecosystem at the Shule River Basin by combining the Keeling plot model and in-situ chamber measurement. Using this data, the moisture recycled rate (mrr) was assessed based on the two-component (Model A) and three-component isotopic mixing models (Model B), respectively. Based on Model A and δ18O ET , the analysis revealed that the mean recycled rate for the entire observation period was 35 %, while it was 26 % during the westerly period (the months dominated by the north branch of prevailing westerlies) and 44 % during the monsoon period (when subtropical moisture from the Indian monsoon penetrated the region). The recycled rate based on Model A and δD ET was slightly larger with a mean value of 41 % during the entire observation period. The recycled rate based on Model B was also significantly higher in comparison with Model A, while the causes for this difference could be the assumption of substituting xylem water for transpiration vapor and the plant water source δD offset. The contribution of recycled moisture was notable lower for heavy rainfall comparing with light rainfall. Our findings provided a new perspective for the investigations of alpine meadow ecosystem hydrological processes. [ABSTRACT FROM AUTHOR]