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The current paper examines the impact of radiation and Marangoni convective boundary conditions on the flow of ternary hybrid nanofluids in a porous medium with mass transpiration effect on it. Estimated PDEs are converted to ODEs with consideration of the corresponding similarity transformations. The obtained non-dimensional reduced equations are solved by analytical process. A unique access based on the Laplace transform (LT) is used to find analytical solutions to the resulting equations. With the use of graphs, the exact solution may be investigated in the presence of many physical parameters such as solid volume fraction parameter, mass transpiration, porosity, radiation. The fluid flow contains three types of nanoparticles: spherical Silver (Ag), cylindrical SWCNT, and platelet graphene. Because of the shape composition of ternary hybrid nanoparticles, variation in concentrations is a primary factor of thermal performance. The shape of nanoparticles in ternary hybrid nanofluids has a major impact, and its application has the advantage of improving the cooling system's thermo-hydraulic performance. [ABSTRACT FROM AUTHOR]

Earth system models (ESMs) from the Coupled Model Intercomparison Project Phase 6 (CMIP6) experiment exhibit a well-known summertime warm bias in mid-latitude land regions – most notably in the central contiguous United States (CUS). The dominant source of this bias is still under debate. Using validated datasets and both coupled and off-line modeling, we find that the CUS summertime warm bias is driven by the incorrect partitioning of evapotranspiration (ET) into its canopy transpiration and soil evaporation components. Specifically, CMIP6 ESMs do not effectively use available rootzone soil moisture for summertime transpiration and instead rely excessively on shallow soil and canopy-intercepted water storage to supply ET. As such, expected summertime precipitation deficits in CUS induce a negative ET bias into CMIP6 ESMs and a corresponding positive temperature bias via local land-atmosphere coupling. This tendency potentially biases CMIP6 projections of regional water stress and summertime air temperature variability under elevated CO2 conditions. Summertime warm bias in the central United States persists in Earth System Models. This bias is dominated by land physics related to transpiration and evaporation partitioning. Improved land physics can constrain projected climate uncertainty. [ABSTRACT FROM AUTHOR]

Electron transpiration cooling (ETC) is a recently proposed approach to manage the high heating loads experienced at the sharp leading edges of hypersonic vehicles. Computational fluid dynamics (CFD) can be used to investigate the feasibility of ETC in a hypersonic environment. A modeling approach is presented for ETC, which includes developing the boundary conditions for electron emission from the surface, accounting for the space-charge limit effects of the near-wall plasma sheath. The space-charge limit models are assessed using 1D direct-kinetic plasma sheath simulations, taking into account the thermionically emitted electrons from the surface. The simulations agree well with the space-charge limit theory proposed by Takamura et al. for emitted electrons with a finite temperature, especially at low values of wall bias, which validates the use of the theoretical model for the hypersonic CFD code. The CFD code with the analytical sheath models is then used for a test case typical of a leading edge radius in a hypersonic flight environment. The CFD results show that ETC can lower the surface temperature of sharp leading edges of hypersonic vehicles, especially at higher velocities, due to the increase in ionized species enabling higher electron heat extraction from the surface. The CFD results also show that space-charge limit effects can limit the ETC reduction of surface temperatures, in comparison to thermionic emission assuming no effects of the electric field within the sheath. [ABSTRACT FROM AUTHOR]

Tree‐mediated methane (CH4) emissions represent an uncertain pathway of the total CH4 flux released from forested ecosystems. We measured the stem CH4 fluxes from Alnus japonica in a riparian wetland of a temperate forest for a year from 2017 to 2018, using automated chambers. The stem CH4 fluxes varied seasonally, showing summertime maxima and wintertime minima. Medians of stem CH4 fluxes were 12.9, 0.5, 0.4, and 13.4 nmol m−2 s−1 during autumn, winter, spring, and summer, respectively. Dissolved CH4 concentration in groundwater beneath the trees was the major controlling factor of the stem CH4 fluxes. Temporal variations in soil environmental conditions (temperature and groundwater level) controlled dissolved CH4 concentrations in groundwater, and accordingly, stem CH4 fluxes. In addition, stem CH4 emissions were observed when the sap flux diminished during the defoliation period. These results indicate that CH4 in the rhizosphere is mainly transported in the gaseous form through intercellular space in trees. Intense rainfall occasionally caused a transient increase in the stem CH4 emissions, which was attributed to the temporal changes in the groundwater flow paths by rainfall affecting the belowground CH4 concentrations. Our findings highlight the need for continuous stem CH4 flux measurements for improved understanding of the controlling factors and future response of CH4 dynamics in forests, with regards to climate change. Plain Language Summary: Methane (CH4) is an important greenhouse gas. Aerated forest soils are assumed to be an atmospheric CH4 sink. However, the results of recent experimental and field studies suggest that tree‐mediated CH4 emissions have the potential to offset the soil CH4 sink and may convert the forest from a net sink to a net source. Tree‐mediated CH4 emissions represent an uncertain pathway of the total CH4 flux from forested ecosystems. In this study, we conducted continuous field measurements for a year, on the stem CH4 fluxes from Alnus japonica standing in a riparian wetland. We found that the seasonal variation in the stem CH4 fluxes is controlled by seasonal variations of the dissolved CH4 concentrations in the groundwater. Temporal changes in soil environmental conditions (temperature and groundwater level) controlled dissolved CH4 concentrations in groundwater. It was also found that intense rainfall causes a transient increase in the stem CH4 emissions. At the study site, changes in the groundwater flow paths by rainfall affect the dissolved CH4 concentrations in the rhizosphere and the stem CH4 flux. Understanding these mechanisms will contribute to the development of models used to estimate the CH4 emissions from forest ecosystems and predict their response to environmental changes. Key Points: The stem CH4 fluxes from Alnus japonica seasonally vary and increase during and after intense rainfallDissolved CH4 concentration in groundwater is a major factor controlling stem CH4 flux as shown by path analysisRhizospheric CH4 is mainly transported in the gaseous form through intercellular space in trees and partly by the transpiration stream [ABSTRACT FROM AUTHOR]

Panels were tested at different locations around the turbine blade, on both suction and pressure surfaces. Three different surface porosities were also tested. Results demonstrated that the approach can be very successful with high levels of film cooling effectiveness, exceeding 95%, achieved using low coolant mass flow rates. Increasing the surface porosity also proved to be an important parameter in the panel's performance. Additionally, staggering the film holes lead to significant positive interactions between individual films, resulting in much improved panel performance. [ABSTRACT FROM AUTHOR]

Cross‐slope climate differences in the midlatitudes are ecologically important, and impact vegetation‐mediated water balance between the earth surface and the atmosphere. We made high‐resolution in situ observations of air temperature, relative humidity, soil moisture, insolation, and sap velocity observations on 14 Pacific madrone trees (Arbutus menziesii) spanning adjacent north and south slopes at the University of California's Angelo Coast Range Reserve. To understand the cross‐slope response of sap velocity, a proxy for transpiration, to microclimate, we modeled the sap velocity on each slope using a transpiration model driven by ambient environment and parameterized with a Markov Chain Monte Carlo parameter estimation process. The results show that trees on opposing slopes do not follow a shared pattern of physiological response to transpiration drivers. This means that the observed sap velocity differences are not due entirely to observed microclimate differences, but also due to population‐level physiological differences, which indicates acclimation to inhabited microclimate. While our present data set and analytical tools do not identify mechanisms of acclimation, we speculate that differing proportions of sun‐adapted and shade‐adapted leaves, differences in stomatal regulation, and cross‐slope root zone moisture differences could explain some of the observed and modeled differences. Plain Language Summary: The transfer of water from plants to the atmosphere is determined by the interaction between plant physiology and local microclimate. We made high‐frequency observations of sap velocity in two populations of Pacific madrone trees across a hillslope divide containing a strong microclimatic gradient. The differences in sunlight between the two slopes lead not only to different temperatures and humidities, but also to differences in energy available for photosynthesis, and hence transpiration. As a result, trees on the south‐facing slope transpire 20% more water over the dry Mediterranean summer. Furthermore, we found that water use by trees on the north slope bears a different relationship to environmental conditions than water use by trees on the south slope. Key Points: Solar radiation differences generate different microclimates across adjacent north‐ and south‐facing slopes in the midlatitudesHigh‐frequency measurements document microclimate and covarying tree water use across a hillslope divide over a dry Mediterranean summerTranspiration of a single tree species is higher on the drier, sunnier south‐facing slope, suggesting different water use strategies [ABSTRACT FROM AUTHOR]

Dense impenetrable thickets of invasive trees and shrubs compete with other water users and thus disrupt ecosystem functioning and services. This study assessed water use by the evergreen Prosopis juliflora, one of the dominant invasive tree species in semi-arid and arid ecosystems in the tropical regions of Eastern Africa. The objectives of the study were to (1) analyze the seasonal water use patterns of P. juliflora in various locations in Afar Region, Ethiopia, (2) up-scale the water use from individual tree transpiration and stand evapotranspiration (ET) to the entire invaded area, and 3) estimate the monetary value of water lost due to the invasion. The sap flow rates of individual P. juliflora trees were measured using the heat ratio method while stand ET was quantified using the eddy covariance method. Transpiration by individual trees ranged from 1–36 L/day, with an average of 7 L of water per tree per day. The daily average transpiration of a Prosopis tree was about 3.4 (± 0.5) mm and the daily average ET of a dense Prosopis stand was about 3.7 (± 1.6) mm. Using a fractional cover map of P. juliflora (over an area of 1.18 million ha), water use of P. juliflora in Afar Region was estimated to be approximately 3.1–3.3 billion m3/yr. This volume of water would be sufficient to irrigate about 460,000 ha of cotton or 330,000 ha of sugar cane, the main crops in the area, which would generate an estimated net benefit of approximately US$ 320 million and US$ 470 million per growing season from cotton and sugarcane, respectively. Hence, P. juliflora invasion in the Afar Region has serious impacts on water availability and on the provision of other ecosystem services and ultimately on rural livelihoods. [ABSTRACT FROM AUTHOR]

Excess heat has a negative effect on the growth and development of fruit plants, their productivity, so the success of introduction under conditions with a hot climate is determined by the plants resistance to overheating. The article presents for the first time the results of the heat resistance study of 10 introduced apple-tree varieties in seasonal dynamics due to their water content, transpiration rate and seasonal development. It was found that the heat resistance varied in different varieties and changed during the growth, decreasing in August-September in all varieties. Maximum values of water content in the leaves was observed in May and minimum in August-September. The maximum transpiration rate was from June to August, depending on variety. High heat resistance, water content and low transpiration rate were observed in all varieties at the end of May, against the background of a drop in the growth rate of shoots. At the completion time of shoot growth and the beginning of fruit ripening, the water content decreased in all varieties, transpiration rate varied in different directions, and heat resistance decreased in all varieties except the most stable ones (Stolovka, Renet Burkhardta). After fruit ripening and shoots lignification, water content, transpiration rate and heat resistance decreased in all varieties. The most productive varieties were characterized by high heat resistance. The work was carried out on the topic of the Grant Project "Introduction of prospective apple-tree varieties for introduction into culture in the arid regions of West Kazakhstan". [ABSTRACT FROM AUTHOR]

Open-cell foam has extensive applications including the transpiration cooling, the porous media combustion, the solid oxide fuel cell, the phase change materials for energy storage and the artificial bone tissue. However, the topology construction of open-cell foam with controlled profiles (i.e. porosity and pore diameter) is of great challenge for the available techniques. There is an urgent need to develop a new topology generation approach of open-cell foam for maximizing the working performance and minimizing the negative impacts in the fields as mentioned above. In this paper, a new method based on the periodic level surface was proposed to build the open-cell foam topology according to the inputting pore profiles. A framework, consisting of the solid matrix-pore interface type selection module, the geometry and pore parameters inputting module, the characteristic parameters of the interface equation calculation module, and the topology simplification and optimization module, was built for the generation of open-cell foam. With the generated topology, pore-scale modelling of transpiration cooling in a T-junction was carried out. A case with uniform pore topology was conducted to analyze the wall temperature and transpiration cooling efficiency. [ABSTRACT FROM AUTHOR]

The influence of localized nitrogen transpiration on second mode instabilities in a hypersonic boundary layer is experimentally investigated. The study is conducted using a 7 ∘ half-angle cone with a length of 1100 mm and small nose bluntness at 0 ∘ angle-of-attack. Transpiration is realized through a porous Carbon/Carbon patch of 44 × 82 mm located near the expected boundary layer transition onset location. Transpiration mass flow rates in the range of 0.05–1% of the equivalent boundary layer edge mass flow rate were used. Experiments were conducted in the High Enthalpy Shock Tunnel Göttingen (HEG) at total enthalpies around 3 MJ/kg and unit Reynolds numbers in the range of 1.4 · 10 6 to 6.4 · 10 6 m - 1 . Measurements were conducted by means of coaxial thermocouples, Atomic Layer Thermopiles (ALTP), pressure transducers and high-speed schlieren. The present study shows that the most amplified second mode frequencies were shifted to lower values as nitrogen is transpired into the boundary layer. In some cases the instability amplitudes were found to be significantly reduced. The observed frequency reduction was verified to correlate with the change of the relative sonic line height in the boundary layer. The amplitude damping was observed to occur only until the most amplified frequencies were reduced to around 50% of their undisturbed values. When transpiration within this limit was performed shortly upstream of the natural boundary layer transition onset, a transition delay of approximately 17% could be observed. [ABSTRACT FROM AUTHOR]

Quantifying transpiration and its response to meteorological factors at a stand scale and different canopy layers of forest is important for understanding the hydrological impact of nitrogen (N) deposition on local water balance. For this purpose, sap flows were measured in three upper (Schima superba, Castanea henryi, and Machilus chinensis) and three lower (Symplocos ramosissima, Ilex ficoidea, and Schefflera octophylla) canopy species based on a manipulative experimental platform with canopy (CN) and understory (UN) N additions in a low‐subtropical evergreen broadleaf forest. Each application included concentrations of 0, 25, and 50 kg·ha−1·a−1 N. Results showed that N addition obviously influenced the sap flux density and such influence varied among different species and between canopy layers. Upper canopy species contributed the most transpiration for the whole forest, and CN25 greatly affected the transpiration in both upper and lower canopy layers. Daily water use (Qd) increased logarithmically with daytime average photosynthetically active radiation and daily average vapor pressure deficit. An appropriate canopy N addition (CN25) promoted the Qd and its sensitivity to micrometeorological factors, whereas UN had a minimal effect. These results suggest a substantial difference in response of transpiration to the N addition ways. CN had more effective influence on the canopy transpiration. Thus, UN could not fully reflect the effects of increased N deposition on the canopy‐associated transpiration, and the response of forest transpiration to N deposition needs to be analyzed beyond species and upscaled to the canopy level in favor of meaningful assessments of N deposition. Key Points: Transpiration response to N deposition needs to be analyzed beyond species and upscaled to forest canopy to achieve meaningful assessmentsSubtropical forests adapt to increased N deposition through the sensitivity adjustment of transpiration to meteorological factorsAn appropriate canopy N addition promoted the forest transpiration and its sensitivity to meteorological factors [ABSTRACT FROM AUTHOR]

In plants, stomata regulate water loss through transpiration for plant growth and survival in response to various environmental stressors; and simple methods to assess stomatal dynamics are needed for physiological studies. Herein, we report a fluorescence-imaging-based method using fluorescein diacetate tagged with Hoechst 33342, a nuclear staining chemical probe (HoeAc2Fl) for the qualitative assessment of stomatal dynamics. In our method, the stomatal movement is inferred by simple monitoring of the fluorescence intensity in the nucleus of the stomata. [ABSTRACT FROM AUTHOR]

Studying the peculiarities of the water status of fruit plants allows revealing the mechanism's of adaptation of introduced species to the arid conditions, their relationship with the development phases and productivity of varieties. The paper presents for the first time the results of a study of leaf water content and intensity of transpiration of 10 introduced apple varieties in their daily and seasonal dynamics. Under the conditions of drop irrigation, a sharp increase in the intensity of transpiration in the middle of the day was revealed for all varieties, as well as fluctuations in the water content of leaves and the intensity of transpiration during the vegetative season associated both with extreme values of air temperature and humidity, and with the phases of growth and development of varieties. In seasonal dynamics, from one to three peaks of water content and transpiration intensity have been noted. The maximum water content of the leaves was observed in May, the maximum transpiration intensity was observed at different times from June to August and for the most productive varieties - on 20th of June. By the amount of transpirating moisture consumption, apple varieties are classified as medium- and low-transpirative. [ABSTRACT FROM AUTHOR]

The main objective of this study was to identify the possibility of using physiological parameters of the growth and development of woody plants as indicators of their resistance to extra-arid conditions of the Mangistau desert. Using generally accepted representative methods for 21 species of deciduous and coniferous trees and shrubs, we determined the seasonal dynamics of transpiration and leaf water content, chlorophyll concentration and heat resistance. By the level of transpiration moisture consumption, all introducers are ranked into 3 groups: low transpiration (<250 mg/g of raw leaf weight per hour), medium transpiration (250-500) and high transpiration (> 500). A high correlation was established between the transpiration intensity (TI) and the water content of leaves of woody plants (r = 0.79). Soil moisture determines from 11.6 to 43.6% changes in transpiration rate (r = 0.34-0.66). Reliable at a significance level of 5% is also the close connection of TI with relative humidity (r = -0.59) and air temperature (r = 0.46). It is statistically unreliable with the indicator of illumination (r = 0.19). For most introducers, seasonal TI dynamics have the appearance of a singlepeak curve with a maximum in June. For the daily transpiration rhythm, three types are distinguished: "rising" (from morning to evening), "falling" (from morning to evening) and "variable" (with a maximum at noon). The intensity of the transpiration process, due to significant variability and multifactorial nature, cannot be ranked among the criteria for resistance of woody plants. At the same time, a significant relationship was established between the biological stability of introducers and the coefficient of variation of IT. With an increase in its values, the tolerance of plants to arid environmental conditions usually increases due to their increased ability to self-regulate water metabolism. For the seasonal variation, the chlorophyll content is characterized by a two-peak curve with peaks in June and September. In the most biologically stable species (Ulmus pumila L., Elaeagnus oxycarpa Schlecht.), Its concentration is less susceptible to seasonal fluctuations. Consequently, the chlorophyll content cannot yet be recognized as a reliable indicator of plant resistance, since it strongly depends on the bioecological properties of introducers, especially in conditions of a desert habitat. According to the degree of heat resistance, plants are ranked in 3 groups: "low" (50 ° C) -3 species; "Medium" (60 ° C) -8 and "high" (70 ° C) -3 taxa. As a genetically fixed bioecological indicator, slightly susceptible to intraspecific changes, it can very well be used as a diagnostic sign of the introduction value of plants in arid conditions. [ABSTRACT FROM AUTHOR]

Large changes in land use and land cover types have been occurring in the hill and gully regions of the Loess Plateau since the end of the 1990s. This study revealed dynamic variations of soil water in different layers of representative land use and land cover types under different annual precipitation regimes and assessed the effects on soil water circulation in large areas of apricot [Armeniaca sibirica (L.) Lam.] trees, which have extensive and deep root systems. The results show distinct soil water deficit with a water content of generally <17% (60% of field capacity) in the deep layers of the soil profile of the apricot orchards. Several years after afforestation, perennial soil water deficit layers have subsequently developed around the root zone or even extended to deeper soil layers in the apricot orchards. In the soil profiles, increasing Cl contents are not related to increasing δ²H and δ18O values. This finding suggests that the extreme deficit of soil water and dry layer developments is mainly caused by intense transpiration, rather than by evaporation alone. The occurrence and development of soil water deficit layers in the deep soil profiles were the dominant factors that caused tree growth degradation and gradual death, due to lack of adequate stored soil water in the deep layers for use during a long arid time. Thus, the large-scale establishment of arbor trees will likely lead to long-term soil desiccation in the arid or semiarid regions on the Loess Plateau. [ABSTRACT FROM AUTHOR]

Wild plum has many medicinal, therapeutic and nutritive uses, but its fruits are collected in the wild and less researched. The aim of this study was to evaluate the effects of storage temperature on postharvest fruit quality of wild plum. The fruits of wild plum were subjected to different storage treatments at 0, 5, 10 and 15 ± 1°C in a completely randomized design. The results showed that as storage temperature decreased below 15°C, the incidence and severity of chilling injury significantly (p<0.05) increased. As storage temperature increased from 0 to 15°C fruit titratable acidity (TTA) and vitamin C content significantly (p< 0.05) decreased, but juice pH, soluble solids content (SSC) and weight loss significantly (p< 0.05) increased. The decrease in TTA and vitamin C content, and increase in SSC and juice pH was attributed to fruit ripening. The increase in fruit weight loss was attributed to higher transpiration and respiration. It was concluded that to extend the storage-life and marketing period of wild plum fruits, the fruits should be stored at 15°C and 90-95% RH. [ABSTRACT FROM AUTHOR]

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Dracaena cinnabari is a relict of the remote Socotra Island (Yemen) where it grows at higher altitudes with the frequent occurrence of fogs. D. cinnabari as the only representative of the dragon tree group creates woodlands and forests on the Socotra Island. It is not clear what mechanisms allow this relict arborescent monocot to survive harsh climate and poor soil of karst rocks there. In this work, we conducted long-term sap flow monitoring in the stem and roots of the mature D. cinnabari plant during the driest period of year between two regular monsoons. We aimed to reveal plant responses to a range of environmental conditions and to understand mechanisms of drought survival by this woody monocot. Several following features of sap flow performance were found: high flow sectoriality in the stem and in roots corresponding to the intensity of insolation, free lateral flow, higher stem integrity compared to roots, internal storage replenishment from the fog followed by increased transpiration presumably from the refilled stem storage. Results indicate that in studying the sap flow dynamics in the mature D. cinnabari tree, plant water storage should be included in the analyses in addition to soil water availability and intensity of evaporating demands. The ability to replenish succulent woody organs from atmospheric water and to survive long periods of drought from the internal supply distinguishes the behavior of this short-rooted arborescent monocot from the known strategies of deep-rooted trees in arid areas. [ABSTRACT FROM AUTHOR]

Highlights • PM increased leaf transpiration by 9.8%˜33.3% and sap flow by 1.4%˜34.5% under different weather conditions. • Plastic mulch shortened the length of growing season and decreased total ET by 4%˜11.8%. • PM altered ET components as PM significantly restrained E. • Plastic mulch provided more water for maize growth thus resulted in significantly higher yield and water use efficiency. Abstract Plastic mulch can significantly improve soil water and temperature conditions in croplands, altering ecohydrological processes in agroecosystems. Therefore, analysis of maize water consumption in response to plastic mulch is of importance to agricultural water management. A field experiment was conducted in non-mulched (CK) and mulched (PM) maize fields of eastern Loess Plateau to monitor maize evapotranspiration at different scales. Portable photosynthesis system, sap flow system and eddy covariance systems were utilized to measure transpiration rate at leaf scale, sap flow at plant scale and evapotranspiration (ET) at field scale, respectively. The results indicated PM provided a wetter condition (+2.8% and +4.2% in soil water content for two growing seasons respectively) for maize, leading to higher leaf area index, plant height and aboveground biomass under PM treatment. PM increased leaf transpiration by 9.8%˜33.3% and sap flow by 1.4%˜34.5% under different weather conditions. However, seasonal ET and the ratio of soil evaporation to ET decreased from 326.3˜341.1 mm and 39.9%˜42.8% under CK to 305.0˜313.9 mm and 23.8%˜34.9% under PM respectively, indicating PM declined seasonal ET and altered ET components, as evaporation decreased while crop transpiration increased. Thus, more water was used for maize growth, finally resulted in significantly higher yield and water use efficiency (p < 0.05). Our results shed light on how plastic mulch saves water and improves water use efficiency, which can provide important information for crop production modeling, water balance evaluation and sustainable management of dryland farming in this area. [ABSTRACT FROM AUTHOR]

Highlights • A non-invasive method to determine soil hydraulic properties is implemented. • Water content measured over time and depth allows to inversely solve for K-θ-h. • Crop available water limits are proposed to be estimated in a process-based way. • No tendency was found between soil available water and land use for the same soil. Abstract Accurate knowledge of soil hydraulic properties (K-θ-h) for the entire range of crop available water is essential for the prediction of soil water movement and related processes by mechanistic models, including the partitioning of surface energy fluxes into transpiration and evaporation and the dynamics of root water uptake, mandatory processes for adjustments of crop water use efficiency. We implemented an experimental and numerical protocol to obtain K-θ-h of eleven soils with a broad spectrum of texture and land use. Measurements of the soil water content during evaporation experiments using gamma-ray beam attenuation, a non-invasive technique, were adopted as an alternative approach to conventional measurements of the soil water pressure head. Inverse parameter optimization was performed using Hydrus-1D. The optimized K-θ-h functions were interpreted with respect to crop available water, where results calculated by a proposed "dynamic" method were compared with those determined using the conventional "static" criteria with standardized pressure heads. The evaporation experiment protocol allowed the determination of the K-θ-h relationships by inverse modeling from near-saturation to the dry range (∼ −150 m) with satisfactory accuracy. Soil water retention curves of the fine-textured soils determined by the conventional method (pressure plates) deviated from those estimated by the inverse optimization near saturation and in the dry range, with the conventional method predicting larger water content values. In terms of crop available water, the "dynamic" method allowed incorporating system characteristics (atmospheric demand and crop properties) and K-θ-h in a process-based way, contrarily to the "static" method. Considering a specific scenario, for the fine-textured soils the "static" and "dynamic" approaches performed similarly, however, for the coarse-textured soils, they diverged significantly. No tendency could be revealed for crop water availability under different land uses, and, in general, crop available water for soils under forest use was very similar to their counterparts under agricultural use. [ABSTRACT FROM AUTHOR]

Abstract High temperature resistant porous ceramics are considered to be prime candidates for applications in the transpiration cooling system of a hypersonic vehicle. This paper describes a new preparation process including grinding-mould pressing-sintering process, which is successfully used to fabricate C/SiC porous ceramics with high compressive strength and excellent permeability. The effects of carbon fiber content on the microstructure, mechanical property, pore size distribution and permeability of this porous ceramic are investigated in detail. The results indicate that this porous ceramic prepared in this study exhibits high compressive strength (∼270.82 MPa) and excellent permeability (∼3.937 × 10−8 mm2). The C/SiC porous ceramics fabricated in this study will have potential application in active thermal protection systems. [ABSTRACT FROM AUTHOR]

This study presents a mathematical model to describe respiration (O2 consumption and CO2 production) and transpiration rates of minimally processed pineapple (cut into slices) as a function of temperature, relative humidity (RH) and geometric configuration. To experimentally adjust suitable models for respiration and transpiration, minimally processed pineapple (Ananas comosus) was stored in slices of three types of configuration (a complete slice with 1 centimeter of thickness, a complete slice with 2 centimeter of thickness and a half slice with 1 centimeter of thickness) at different temperature and RH. To estimate respiration rates, two possible models were compared and the most suitable one was chosen: the O2 consumption and CO2 production were modeled by using a Michaelis-Menten enzyme kinetics and by using a first-order kinetics choosing the former. Throughout the different experiments, the respiration rates were higher by increasing the storage temperature. The transpiration data shows the weight loss is linear for all the samples during the entire storage time. Transpiration was represented by considering the mass transfer (of moisture) due the water activity gradient between the produce and the atmosphere surrounding it, and the water evaporated as a consequence of absorbing the respiratory heat generated in the cut fruits. Results shows a high goodness of fit between experimental data and estimated values with the respiration-transpiration models (R² adj > 0.88). [ABSTRACT FROM AUTHOR]

Highlights • This study used a logic function to model the external surface conditions. • The developed modeling method utilizes the concept of "convolution". • A two-step training approach for the convolution kernel was developed. • The convolution model could be used for cooling optimization. Abstract Transpiration cooling has been widely used in many components operating under extremely high temperature, due to its advantage of uniform cooling, high efficiency and low coolant consumption. Recently matured metallic additive manufacturing technologies pushed transpiration cooling to a new stage with its extensive precision in fabricating micro regular features for porous media. As a result, micro controlling of porous features and developing thermal-load-adaptive transpiration cooling became possible. However, the large number of holes inside the porous media could cause a parameter exploding for investigating additive manufactured transpiration cooling structures, if each hole was treated separately. Meanwhile, the coolant accumulation phenomena remained to be a complex problem to understand or model. The present study proposed a convolution modeling method, which took advantage of convolution functions to model the cooling effectiveness of transpiration cooling with complex hole distribution. The proposed convolution model included an input layer, a convolution layer and an output layer. A single logic matrix was used as the input to dramatically reduce the dimension of parameter space. As convolution used the weighted average logic value of a range of neighboring regions, it was capable to reproduce the internally links and interactions of different coolant jets. Based on a series of numerical results, the model was initialized and trained to achieve a relative error around 4.04%. The model was further validated by several more complex geometries and demonstrated good accuracy in predicting transpiration cooling efficiency. This effort established a novel method to model transpiration cooling that could be additively manufactured. Compared with traditional correlation formulas, this network-like model had a much higher resolution while still preserving the low computational cost. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Mass transfer in ducts with transpiring walls was analysed. • New dimensionless numbers appropriate to transpiration problems were introduced. • The simplifying assumption of self-similar concentration profiles was made. • Under this assumption, a simple theory was developed to predict the Sherwood number. • Predictions were validated against CFD results based on no simplifying assumption. Abstract The problem of mass transfer in ducts with transpiring walls is analysed: the concepts of "solvent" and "solute" fluxes are introduced, all possible sign combinations for these fluxes are considered, and relevant examples from membrane processes such as electrodialysis, reverse osmosis and filtration are identified. Besides the dimensionless numbers commonly defined in studying flow and mass transfer problems, new dimensionless quantities appropriate to transpiration problems are introduced, and their limiting values, associated with "drying", "desalting" and "saturation" conditions, are identified. A simple model predicting the Sherwood number Sh under all possible flux sign combinations is derived from the single simplifying assumption that concentration profiles remain self-similar (so that the Sherwood number based on diffusion only remains unchanged) also under transpiration conditions. The simple model provides not only local values of Sh, but also its axial profiles. Predictions are validated against fully predictive CFD results, not based on the above simplifying assumption, and a good agreement is demonstrated provided the transpiration rate complies with certain limitations, depending on the Schmidt number. [ABSTRACT FROM AUTHOR]

Stomata serve dual and often conflicting roles, facilitating carbon dioxide influx into the plant leaf for photosynthesis and restricting water efflux via transpiration. Strategies for reducing transpiration without incurring a cost for photosynthesis must circumvent this inherent coupling of carbon dioxide and water vapor diffusion. We expressed the synthetic, light-gated K+ channel BLINK1 in guard cells surrounding stomatal pores in Arabidopsis to enhance the solute fluxes that drive stomatal aperture. BLINK1 introduced a K+ conductance and accelerated both stomatal opening under light exposure and closing after irradiation. Integrated over the growth period, BLINK1 drove a 2.2-fold increase in biomass in fluctuating light without cost in water use by the plant. Thus, we demonstrate the potential of enhancing stomatal kinetics to improve water use efficiency without penalty in carbon fixation. [ABSTRACT FROM AUTHOR]

Highlights • A porous module with a treelike micro-channel was additive manufactured. • Coolant water automatically flowed to the heated surface without any pump. • Coolant flow automatically adjusted the to adapt to the changing heat flux. Abstract Self-pumping transpiration cooling is an effective method to cool a heated surface without a pump and control system. A porous module with a tree-like micro-channel was manufactured using a metal additive manufacturing method. A metal ceramics heater was used to heat the additive manufactured porous module to test the transpiration cooling effect. The experimental results showed that the coolant water automatically flowed from the water tank to the heated surface with a height difference of 90 mm without any pump. The porous module was efficiently cooled by self-pumping internal transpiration cooling while the temperature of the micro-hole layer was approximately 373 K. The coolant mass flow rate self-adaptively increased with the increase of the heat flux. The system automatically, in a timely manner, and accurately adjusted the coolant mass flow rate to adapt to the step and sinusoidal changed heat flux, and the temperature of the micro-hole layer remained approximately 373 K. The system worked well when the porous module had different angles with the gravity direction. The heated surface was effectively cooled, even when the porous module was upside-down. [ABSTRACT FROM AUTHOR]

To clarify the response of net photosynthetic rate (Pn), stomatal conductance (gS), transpiration rate (Tr), and leaf intercellular CO2 concentration (Ci) to irradiance on the adaxial and abaxial sides of mature and young strawberry leaves using blue, green, and red light-emitting diodes (LEDs), irradiation from a short distance was investigated using 'Tochiotome'. Light--photosynthetic response curves of the adaxial side of mature leaves were not different amongLED treatments.However, those of the adaxial side of young leaves irradiated with red LEDs were less than those of other LED treatments. Pn of the abaxial side of mature leaves was 42% to 71% of the abaxial side. In young leaves, Pn of the abaxial side was 17%to 68% of the adaxial side.Moreover, light--transpiration response curveswere different with LED treatments. Ci and Tr under blue and green LEDs were greater than those under red LEDs. This indicates that blue and green lights affected the stomatal opening. In contrast, red LEDs decreased Ci more than other LED treatments. In addition, reactions of the adaxial side of young leaves under blue and red LEDs were seen not only in 'Tochiotome', but also in 'Sachinoka' and 'Eran', which indicates that the photosynthetic reactions of blue light and red light are commoncharacteristics of the strawberry. Therefore, red LEDs promoted the photochemical reaction and activated the CO2 fixation system. Based on the results of this study of short-distance lighting with LEDs in strawberry production, irradiance of the abaxial side of leaves by blue or green LEDs might improve more assimilates in young leaves compared with red LEDs to increase strawberry yield. [ABSTRACT FROM AUTHOR]

Abstract Stomatal transpiration of leaves is a dominant pathway of plant physiological water loss. The leaf transpiration rate when stomata are fully open is commonly at the same level as the evaporation rate of a wet surface of the same area as that of the leaf area, although the cumulative area of the stomatal pores is typically less than 3% of the leaf area. To elucidate the highly efficient diffusion of the stomatal array from the perspective of mass transfer theory, stomatal distribution characteristics of various kinds of leaves were obtained with optical microscope, and steady diffusions of water vapor from isolated zero-depth circular stomata, elliptical stomata, and distributed stomatal arrays without airflow parallel to the surface were simulated with the finite element method. It was found that the long perimeter of the elliptical stomata and the specific distribution characteristics of the stomatal array are the dominant reasons for the highly efficient diffusion of the stomatal array on the leaves. Furthermore, the simulation results reveal that extremal transpiration rates exist for the stomatal arrays with different distribution characteristics. It was found that the transpiration rates of the vegetation tend to approach the extremal values for flourishing development in the process of natural optimization. [ABSTRACT FROM AUTHOR]

A paper has recently been published in Water Resources Research, which explored the influence of smallholder's perceptions regarding water availability on crop choice and water allocation through social‐hydrological modeling. The present paper attempts to discuss and comment on that paper. The authors have developed a social‐hydrological model, behind which some assumptions of the hydrological aspects (including the omission of deep percolation and the complete separation of transpiration and evaporation for the growing season and the off season) are not well justified. Further, a few parameter values seem to be mistakenly presented by the authors. Most importantly, the equation used for calculating the irrigation depth for crop 1 was incorrectly derived, which could lead to apparent biases in the simulated soil moisture, drought memories, and crop fractions. Hence, the key findings of Kuil et al. (2018, https://doi.org/10.1002/2017WR021420) might be associated with large uncertainties and should be interpreted with much caution. Key Points: The present paper attempts to discuss and comment on a paper recently published in Water Resources ResearchSome assumptions of the hydrological aspects within the social‐hydrological model are not well justifiedThe irrigation depth for crop 1 was incorrectly estimated, which could bring significant biases to the simulations [ABSTRACT FROM AUTHOR]

Highlights • Nitrogen (N) applied to reach the sufficiency leaf N threshold level (2%) in olive reduced root length intensity. • N application may not be required if pre-plant soil NO 3 levels are normal (∼ 25 mg kg−1). • Gas exchange measurements are not recommended to assess the influence of N application in olives. Abstract Nitrogen (N) status in olive trees is critical to develop several developmental mechanisms that control shoot, root and nutrient uptake capacity. The objective of this field study was to assess the effect of N level and form on root growth dynamics, shoot growth, leaf-level gas exchange [ photosynthesis (Pn), transpiration (E), and stomatal conductance (gs)] and leaf nutrient content of young olive (Olea europaea cv. Arbequina) trees. Olive cuttings were planted in the field and grown for two years (2015, 2016). In both years, cuttings were subjected to 7 N treatments: control (no N), nitrate (NO 3 −) form applied as calcium nitrate (CN) at 20, 40 and 60 kg ha-1, and ammonium (NH 4 +) applied as urea at 20, 40 and 60 kg ha-1. Minirhizotron image analysis showed that the application of N significantly reduced root length intensity (L a , mm cm-2) compared to control olives in both years. No significant difference was noticed between N forms for L a in 2015. However, CN treatment had higher L a than urea in April and June 2016. In addition, the overall mean of L a across the study period (2015–2016) showed that L a in the lower soil depths, 40–60 and 60–80 cm was significantly higher than those from the top layers, 0–20 and 20–40 cm. Unfertilized (control) cuttings had also higher tree height, stem diameter and branch number than olives that received 40 or 60 kg ha-1-N across the study period (2015-2016). In both years, leaf N% in control olives was above the N deficiency thresholds; i.e. 2.1% in 2015 and 2.57% in 2016. However, leaf mineral concentrations were inconsistent (P, Ca+2, Na, Zn, Fe, Cu) or not significant (Mn, S and B). In addition, no significant difference was noticed between treatments in gas exchange (Pn , gs and E). Overall, untreated-control young olive trees showed consistently higher L a and shoot growth than N-treated trees (CN and urea) over the study period 2015-2016. Therefore, N application is not needed if leaf N levels are normal during the previous season. In fact, high rates of N in the soil during establishment of young olive trees can negatively affect root and shoot growth. [ABSTRACT FROM AUTHOR]

The efficacy of the cuticular transpiration barrier and its resistance to elevated temperatures are significantly higher in a typical water-saver than in a water-spender plant growing in hot desert. Water-saver and water-spender strategies are successful adaptations allowing plants to cope with the limitations of hot desert habitats. We investigated whether the efficacy of the cuticular transpiration barrier and its susceptibility to high temperatures are ecophysiological traits differentially developed in the water-spender Citrullus colocynthis and the water-saver Phoenix dactylifera. Minimum leaf conductance (g min) at 25 °C was six times lower in P. dactylifera (1.1×10–5 m s–1) than in C. colocynthis (6.9×10–5 m s–1). Additionally, g min in the range 25–50 °C did not change in P. dactylifera but increased by a factor of 3.2 in C. colocynthis. Arrhenius formalism applied to the C. colocynthis g min led to a biphasic graph with a steep increase at temperatures ≥35 °C, whereas for P. dactylifera the graph was linear over all temperatures. Leaf cuticular wax coverage amounted to 4.2±0.4 µg cm–2 for C. colocynthis and 29.4±4.2 µg cm–2 for P. dactylifera. In both species, waxes were mainly composed of very-long-chain aliphatics. Midpoints of the wax melting ranges of P. dactylifera and C. colocynthis were 80 °C and 73 °C, respectively. We conclude that in P. dactylifera a particular wax and cutin chemistry prevents the rise of g min at elevated temperatures. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the effect of autochthonous microorganisms present in soil collected from heavy metal (HM) uncontaminated (Pb ≈ 59 mg kg−1, Cd ≈ 0.4 mg kg−1, Zn ≈ 191 mg kg−1), moderately (Pb ≈ 343 mg kg−1, Cd ≈ 12 mg kg−1, Zn ≈ 1876 mg kg−1), and highly (Pb ≈ 1586 mg kg−1, Cd ≈ 57 mg kg−1, Zn ≈ 3280 mg kg−1) contaminated sites on Zea mays elemental composition, physiological status, and growth parameters. For this purpose, half of the collected soil was sterilized and soil characterization was performed. After 45 days of cultivation, the presence of HM in the soil negatively affected photosynthesis and transpiration rates, relative chlorophyll content, anthocyanins index, chlorophyll fluorescence parameters, and content of oxidative stress products (H2O2 and Malondialdehyde) of Zea mays, while soil sterilization had a positive effect on those parameters. Average percentage of colonization of root segments by arbuscular mycorrhiza fungi decreased with an increase of HM contamination in the soil. The increase in shoot concentration of HMs, particularly Cd and Zn, was a result of contaminated soils sterilization. Aboveground biomass of maize cultivated on sterilized soil was 3-fold, 1.5-fold, and 1.5-fold higher for uncontaminated, moderately contaminated and highly contaminated soils respectively when compared to nonsterilized soils. Contrary to our expectation, autochthonous microflora did not improve plant growth and photosynthetic performance; in fact, they had a negative effect on those processes although they did reduce concentration of HMs in the shoots grown on contaminated soils. [ABSTRACT FROM AUTHOR]

Background: Sugar beet is a highly salt-tolerant crop. However, its ability to withstand high salinity is reduced compared to sea beet, a wild ancestor of all beet crops. The aim of this study was to investigate transcriptional patterns associated with physiological, cytological and biochemical mechanisms involved in salt response in these closely related subspecies. Salt acclimation strategies were assessed in plants subjected to either gradually increasing salt levels (salt-stress) or in excised leaves, exposed instantly to salinity (salt-shock). Result: The majority of DEGs was down-regulated under stress, which may lead to certain aspects of metabolism being reduced in this treatment, as exemplified by lowered transpiration and photosynthesis. This effect was more pronounced in sugar beet. Additionally, sugar beet, but not sea beet, growth was restricted. Silencing of genes encoding numerous transcription factors and signaling proteins was observed, concomitantly with the up-regulation of lipid transfer protein-encoding genes and those coding for NRTs. Bark storage protein genes were up-regulated in sugar beet to the level observed in unstressed sea beet. Osmotic adjustment, manifested by increased water and proline content, occurred in salt-shocked leaves of both genotypes, due to the concerted activation of genes encoding aquaporins, ion channels and osmoprotectants synthesizing enzymes. bHLH137 was the only TF-encoding gene induced by salt in a dose-dependent manner irrespective of the mode of salt treatment. Moreover, the incidence of bHLH-binding motives in promoter regions of salinity-regulated genes was significantly greater than in non-regulated ones. Conclusions: Maintaining homeostasis under salt stress requires deeper transcriptomic changes in the sugar beet than in the sea beet. In both genotypes salt shock elicits greater transcriptomic changes than stress and it results in greater number of up-regulated genes compared to the latter. NRTs and bark storage protein may play a yet undefined role in salt stress-acclimation in beet. bHLH is a putative regulator of salt response in beet leaves and a promising candidate for further studies. [ABSTRACT FROM AUTHOR]

Highlights • The architecture of the mango fruit cuticle varies drastically among six cultivars. • The chemical composition of mango cuticle shows postharvest alteration. • Differences in water transpiration are associated with several cuticular features. • Cuticle thickness likely provides resistance to fruit fly infestation. Abstract The cuticle is a critical barrier covering the surface of plant aerial organs. It is associated with important physiological and biological fruit traits, but few studies on this structure have been conducted in tropical fruit such as mango. Here, we have reported on a detailed investigation on the cuticle of six cultivars of mangoes (Kent, Tommy Atkins, Manila, Ataulfo, Criollo and Manililla), by combining several advanced microscopy tools and chemical analyses. All mango cultivars exhibited high variability in cuticle architecture, epicuticular wax layer (EWL) deposition, and different pattern of changes in cutin monomers. Mango cultivars exhibited different water transpiration rates, firmness and fruit quality appearance during postharvest shelf life (PSL), which could not be simply explained by an isolated cuticle structural feature. However, mango cuticles of premium mangos such as Kent, Tommy and Ataulfo displayed prominent cuticle deposition during PSL compared to other cultivars. Tommy fruit with large wax deposition, marginal number of lenticels and prominent cuticle thickening during PSL, exhibited lower percentage of weight lost by transpiration and less visual deterioration of all mango cultivars studied. In contrast, Criollo fruit, with a significant number of lenticels, small EWL, and marginal cuticle thickening during PSL were associated with the highest rate of water transpiration, fruit deterioration, and abscisic acid content. Our results partially explain the resistance patterns to fruit fly attack documented in earlier studies, clearly showing that cultivars such as Criollo are highly susceptible whereas Tommy, Kent, and Ataulfo are resistant because of the cuticle characteristics described in this study. [ABSTRACT FROM AUTHOR]

Highlights • The modified local thermal non-equilibrium two-phase mixture model is developed. • Model and numerical solutions are validated by comparisons with the previous experimental data. • The transpiration cooling processes with phase change under hypersonic condition are simulated. • The phenomenon that one coolant injection pressure may correspond to multiple mass flow rates is revealed. Abstract Owing to the huge phase-change latent heat, transpiration cooling using liquid coolant has been widely recognized as an effective thermal protection approach for hypersonic vehicles. This paper presents a modified local thermal non-equilibrium two-phase mixture model (LTNE-TPMM), and develops a multi-region numerical strategy to solve the coupled problems of internal heat and mass transfer in a porous cone with the external aerodynamic heat/force. The modified LTNE-TPMM and numerical strategy are validated by the experimental data obtained under a supersonic condition. Using the validated model and numerical strategy, numerical simulations are carried out under the condition of flight Mach number 7.0 and altitude 26.5 km, to study the mechanisms and analyze the performances of the transpiration cooling with liquid phase-change in a porous wedge-shaped nose cone. The numerical results revealed some interesting, valuable phenomena generated in liquid phase-change process, including the coolant movement and the distributions of temperature, pressure, saturation within the porous cone. The coolant mass flux along the radial direction of the cone decreases gradually in the vapor region, and then decreases rapidly at the beginning of two-phase region, but increases in the liquid region. Another important discovery is that the relation between coolant injection pressure and mass flow rate is not one-to-one. One injection pressure may correspond to multiple mass flow rates. [ABSTRACT FROM AUTHOR]

Abstract A platelet transpiration is introduced to strengthen the cooling effect in reattachment region for opposing jet in hypersonic flow. This introduced means can strengthen the local thermal protection performance without leading to an overall enhanced cooling intensity, being helpful on saving the total cooling gas. The two-equation SST k – ω turbulence model has been utilized to study the heat reduction and flow fields of the simplified combinational nose-tip in hypersonic flow. At first, the influence of individual pore are analyzed. The obtained results show that transpiration gas forms a cooling film adhering to the body surface which isolates the serious aerodynamic heating. The transpiration pores which are located on upstream margin of the reattachment point exhibit the best cooling effect. Then, the combination nose-tip is improved. A limited amount of pores are arranged in the reattachment region merely to strengthen the local cooling efficiency. The cooling capacity is obviously promoted with transpiration gas in contrast to that without transpiration. The peak heat flux reduces more than 12% with the mass flux of total cooling gas only promotes by 7.5%. Finally, the study demonstrates that the simplified model with limited amount of pores promote the cooling efficiency in contrast to that without transpiration. [ABSTRACT FROM AUTHOR]

Abstract Transpiration plays a critical role in the water cycle of terrestrial ecosystems, especially for arid ecosystems in which water availability is typically the main constraint for plant growth. Although remote sensing has provided insights into transpiration across different temporal and spatial scales, its potential has not been fully exploited. This is due to a lack of synchronous observations of fluxes and reflectance. Only a few models have attempted to incorporate both radiative transfer and physiological processes. In this study, we calibrated the newly developed Soil, Canopy Observation, Photochemistry and Energy fluxes (SCOPE) model to trace synchronous fluxes of water, energy and reflectance, and thus, their interplays, in a typical arid ecosystem dominated by Haloxylon ammodendron based on long-term continuous field measurements. An initial global sensitivity analysis is conducted to identify parameters that have the greatest impact on model output before subsequent calibration with field data. The resulting calibrated model gives insight into the interplay between reflectance, energy and water fluxes in an arid ecosystem. The calibrated model is thus a useful tool to understand land surface fluxes and radiative transfer processes theoretically, from which additional reflectance information can be exploited to trace the physiological status of ecosystems. Graphical abstract Image Highlights • Long term synchronous measurements were conducted in a desert ecosystem. • Calibrated SCOPE model simulated fluxes and reflectance satisfactorily. • The interplay between reflectance and fluxes of desert plant was newly revealed. [ABSTRACT FROM AUTHOR]

Abstract The possibility and the mechanisms of liquid transport in nanotubes by the effect of thermal transpiration phenomenon are discussed using molecular dynamics simulation (MD) method. Based on the results, it is demonstrated that the thermal transpiration flow for liquids can be established by imposing a temperature gradient to the wall of a nanoscale tube. It can be deduced from MD results that this flow is mainly due to the asymmetric pressure distribution in a narrow region near the tube wall. Fluid layering phenomenon near the wall together with the induced temperature gradient causes the potential component of the pressure in the narrow region near the cold side of the tube becomes higher than the hot side. This causes the fluid to flow in the direction of the temperature gradient. It is shown that the thermal transpiration flow is a plug-like flow. This phenomenon can be used in designing thermal pumps for fluids. The effect of several effective parameters in fluid pumping is investigated. Results show that increasing the imposed temperature gradient, decreasing the nanotube diameter and increasing the fluid-wall binding energy augments the thermal transpiration effect. [ABSTRACT FROM AUTHOR]

Rain recharges soil water storages and either percolates downward into aquifers and streams or is returned to the atmosphere through evapotranspiration. Although it is commonly assumed that summer rainfall recharges plant-available water during the growing season, the seasonal origins of water used by plants have not been systematically explored. We characterize the seasonal origins of waters in soils and trees by comparing their midsummer isotopic signatures (δ2H) to seasonal isotopic cycles in precipitation, using a new seasonal origin index. Across 182 Swiss forest sites, xylem water isotopic signatures show that summer rain was not the predominant water source for midsummer transpiration in any of the three sampled tree species. Beech and oak mostly used winter precipitation, whereas spruce used water of more diverse seasonal origins. Even in the same plots, beech consistently used more winter precipitation than spruce, demonstrating consistent niche partitioning in the rhizosphere. All three species' xylem water isotopes indicate that trees used more winter precipitation in drier regions, potentially mitigating their vulnerability to summer droughts. The widespread occurrence of winter isotopic signatures in midsummer xylem implies that growing-season rainfall may have minimally recharged the soil water storages that supply tree growth, even across diverse humid climates (690–2068 mm annual precipitation). These results challenge common assumptions concerning how water flows through soils and is accessed by trees. Beyond these ecological and hydrological implications, our findings also imply that stable isotopes of δ18O and δ2H in plant tissues, which are often used in climate reconstructions, may not reflect water from growing-season climates. [ABSTRACT FROM AUTHOR]

Feedbacks between soil moisture and convective precipitation are not well represented in current Earth system models, and can affect projections of drought and heavy‐precipitation extremes. To explore the atmospheric and land‐surface influences on the initiation (triggering) of daytime deep convection, single‐column model experiments were performed using the NCAR Community Earth System Model (CESM1.2), over the U.S. Southern Great Plains. The results indicate that the positive and negative feedback mechanisms found in earlier studies (using simplified boundary‐layer models) are robust to large‐scale forcing and interactions between boundary‐layer turbulence, cloud dynamics, and radiation. However, systematic responses of convective triggering to soil moisture emerged only after switching from a convective available potential energy‐based to a convective inhibition energy‐based convective parameterization. This suggests that the choice of convective mass‐flux closure largely determines the sensitivity of parameterized convective clouds to land‐surface state. Errors in land‐model parameterizations of evapotranspiration also affect the probability of deep convection, with vegetation (transpiration) playing an important role in linking soil moisture to surface energy partitioning and clouds. Parameterizations that permit the triggering feedback mechanism better predict the statistics of daytime shallow and deep convection, with respect to observations from the Atmospheric Radiation Measurement site in the Southern Great Plains. The results illustrate how errors in the representation of evapotranspiration in land‐surface models can propagate through the chain of coupled land‐atmosphere processes to affect convective clouds. Key Points: Surface and atmospheric controls on convective triggering can be identified using experiments with a single‐column climate modelModeled responses of convective triggering to soil moisture are strongly influenced by convective cloud and land‐surface parameterizationsParameterizations that permit soil moisture‐triggering feedback mechanisms better predict statistics of daytime shallow and deep cumulus [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Three layer-coatings of both starch and starch-whey protein were applied to plums. • The resistances in the water vapour pathway of fruit coated with 3 layers were analysed. • The used method allows the quantitative assessment of all water loss components. • Starch-based coatings increased the total resistance of plums by a maximum of 60–75%. Abstract A method to characterising the surface water relations of coated fresh fruit has been developed. Based on a modification of the Fick's law of diffusion, application of this method allows for a quantitative assessment of the impact of produce type and of production method of coating, and environment on water losses both of the fruit body and the coating. Resistances in the water vapour pathway were analysed to determine the effects of coating on the surface water relations of plums. Experiments were conducted, evaluating the dynamic behaviour of two different starch-based coatings both at high and low potential water losses. Applying three layer-coatings, both starch and starch-whey protein coatings increased the total resistance in the water vapour pathway of individual plums by 60–75% at high transpiration potentials. Even at low transpiration potentials, an increase of 11–20% was observed. The starch coating tended to have a slightly lower effectiveness than the coating enriched with 20% whey protein. [ABSTRACT FROM AUTHOR]

Knowledge of productive and nonproductive water loss of okra [Abelmoschus esculentus (L.) Moench] is essential during water scarcity, and for assessing links between yield and water use. The study was conducted using subsurface drip irrigation to evaluate okra transpiration and evaporation using the SIMDualKc Model. The model computed soil evaporation was 132.89 and 157.84 mm, respectively, whereas transpiration was 381.22 and 340.36 mm in 2016 and 2017, respectively. Pod yield of okra was 12.1 and 12.5 t∙ha−1; dry biomass above ground was 5.7 and 4.9 t∙ha−1 in 2016 and 2017. Biomass above ground and fresh pod yield of okra indicates that high water deficit before harvesting pods causes a depression in fresh fruit yield and decreases total pod yield. Several water deficit occurrences during the growing period lowers total transpiration and adversely impacts okra dry biomass above ground. The SIMDualKc Model is capable of quantifying evaporation, transpiration and other water balance components. It is an effective tool for assessing and predicting the impact of water deficit on plant development and yield and can be used to identify the correct irrigation strategy for maximizing crop production. [ABSTRACT FROM AUTHOR]

The tropical dry forest (TDF) is one of the most affected ecosystems by anthropic activities in the world; so, it is necessary to study the dynamics of its ecosystem in order to restore it. With the aim of determining the survival, development, and photosynthetic behaviors of forest species at a young age, a field study was performed using three species Cedrela odorata L. (Spanish cedar), Pachira quinata (Jacq.) W.S. Alverson (red ceiba) and Ochroma pyramidale (Cav. ex Lam.) Urb. (balsa) species. Field data were collected in different periods whose climatic conditions were: dry period (S.0), first rainy period (Ll.1), first dry period (S.1), second rainy period (Ll. 2), and second dry period (S.2). The total height (H) and the root collar diameter (RCD) were measured repeatedly, and two harvests were made to measure dry weight. Besides, photosynthetic performance and its effect on the species development species during three contrasting rainfall periods was evaluated by measuring photosynthetically active radiation (PAR), stomatal conductance (gs), intercellular carbon (Cint), net photosynthesis (NP), transpiration (trans), efficient water use (EWU) and efficient light use (ELU) from 8:00 and 17:00 h during the day. Analysis of variance was performed obtaining significant differences (P<0.05) in the interaction time x species regarding variables H and RCD, and the photosynthetic variable NP. The gs and trans variables showed statistical significance with the species and rainfall periods; Cint was significant only for the rainfall periods. The species O. pyramidale presented the best survival and tolerance to weather by adapting physiological mechanisms, while C. odorata was the most affected species by climatic conditions concerning overall survival. [ABSTRACT FROM AUTHOR]

Peanut is a major oilseeds crop of India with its largest area in the world, but its productivity is less than the world average. Though India has released a number of peanut cultivars, studies on the physiological efficiencies of such varieties are scarce. In this study, we tried to elucidate the physiological basis, net photosynthesis (PN), transpiration (E), stomatal conductance (gs), chlorophyll fluorescence (Fv/Fm), SPAD chlorophyll meter reading (SCMR), chlorophyll (chl) contents in leaf at 60-65 days of crop and pod and haulm yields at harvest in 186 peanut cultivars during Kharif season. The average and range of PN were 19.8 and 11.4-31.4 μ mol m-2s-1, gs 0.25 and 0.11-0.45 m s-1, E 6.84 and 3.96-11.61 m mol m-2s-1, SCMR 34.0 and 20.3-44.1, total chl 7.79 and 3.07-15 mg g-1 leaves, Fv/Fm 0.846 and 0.802-0.887, pod yield 179 and 68-309 g m-2 and haulm yield 464 and 144-884 g m-2 and a number of superior cultivars identified. The pod yield was strongly correlated with SCMR, chl and carotenoid contents, haulm yield and pods plant-1, but weakly associated with PN, gs, and Fv/Fm. The PN correlated with gs and E, however, SCMR was the single best parameter. The Spanish and Virginia bunch groups showed most desirable physiological traits. The cultivars TPG 41, Chintamani, M 37, GG 8, GG 13, Kadiri 7 and M 522 showed superior physiological traits for their cultivation. [ABSTRACT FROM AUTHOR]

Highlights • The transpiration dynamics of lettuce plants varied as a function of their water status. • The transpiration was modelled with a second order transfer function. • The parameters of the transfer function varied with crop response. • The model residuals contained information on the plant water status. Abstract Real-time information on the plant water status is an important prerequisite for the precision irrigation management of crops. The plant transpiration has been shown to provide a good indication of its water status. In this paper, a novel plant water status monitoring framework based on the transpiration dynamics of greenhouse grown lettuce plants is presented. Experimental results indicated that lettuce plants experiencing adequate water supply transpired at a higher rate compared to plants experiencing a shortage in water supply. A data-driven model for predicting the transpiration dynamics of the plants was developed using a system identification approach. Results indicated that a second order discrete-time transfer function model with incoming radiation, vapour pressure deficit, and leaf area index as inputs sufficiently explained the dynamics with an average coefficient of determination of R T 2 = 0.93 ± 0.04. The parameters of the model were updated online and then applied in predicting the transpiration dynamics of the plants in real-time. The model predicted dynamics closely matched the measured values when the plants were in a predefined water status state. The reverse was the case when there was a significant change in the water status state. The information contained in the model residuals (measured transpiration – model predicted transpiration) was then exploited as a means of inferring the plant water status. This framework provides a simple and intuitive means of monitoring the plant water status in real-time while achieving a sensitivity similar to that of stomatal conductance measurements. It can be applied in regulating the water deficit of greenhouse grown crops, with specific advantages over other available techniques. [ABSTRACT FROM AUTHOR]

Lack of data on water use of key species of drylands constitutes an obstacle to understanding their role in hydrological processes in this environment. To elucidate seasonal variation in water consumption by Vitellaria paradoxa, the dominant species of parklands of the semi-arid areas of West Africa, we’ve measured its transpiration using heat ratio method (HRM) and seven potential explanatory variables. Sap flux was found to be significantly different among years with 0.64, 0.59 and 0.67 L h−1 dm−2 in 2008, 2009 and 2010, respectively. Sap flux was significantly higher in the dry (0.73 L h−1 dm−2) than in the wet season (0.53 L h−1 dm−2). Nighttime sap flux during dry season (0.48 L h−1 dm−2) was significantly higher than that of the wet season (0.20 L h−1 dm−2) and it contributes on average to 26% of daily sap flow with a maximum reaching 49%. The mean transpiration rate per tree was 151 L day−1 and all measured variables except rainfall and soil water content were significantly correlated with sap flux. These correlations were stronger (higher R value) during the rainy than in the dry season. Vapor Pressure Deficit (VPD) explained the highest proportion of sap flux variation and their curve was of parabolic type (R2 = 0.54) indicating that V. paradoxa can probably down-regulate its canopy conductance beyond a certain threshold of VPD, which is about 3 kPa in the present study. Future studies should investigate such hypothesis as well as the impacts of the variation of V. paradoxa transpiration due to climatic variables on hydrological cycles. [ABSTRACT FROM AUTHOR]