Leaf Wettability Research Articles

Leaf wettability and leaf angle affect air-moisture deposition in wheat for self-irrigation

BackgroundClimate change and depleting water sources demand scarce natural water supplies like air moisture to be used as an irrigation water source. Wheat production is threatened by the climate variability and extremes climate events especially heat waves and drought. The present study focused to develop the wheat plant for self-irrigation through optimizing leaf architecture and surface properties for precise irrigation.MethodsThirty-four genotypes were selected from 1796 genotypes with all combinations of leaf angle and leaf rolling. These genotypes were characterized for morpho-physiological traits and soil moisture content at stem-elongation and booting stages. Further, a core set of ten genotypes was evaluated for stem flow efficiency and leaf wettability.ResultsBiplot, heat map, and correlation analysis indicated wide diversity and traits association. The environmental parameters indicated substantial amount of air moisture (> 60% relative humidity) at the critical wheat growth stages. Leaf angle showed negative association with leaf rolling, physiological and yield traits, adaxial and abaxial contact angle while leaf angle showed positive association with the stem flow water. The wettability and air moisture harvesting indicated that the genotypes (coded as 1, 7, and 18) having semi-erect to erect leaf angle, spiral rolling, and hydrophilic leaf surface (<90o) with contact angle hysteresis less than 10o had higher soil moisture content (6-8%) and moisture harvesting efficiency (3.5 ml).ConclusionsThese findings can provide the basis to develop self-irrigating, drought-tolerant wheat cultivars as an adaptation to climate change.

Leaf Wettability Difference Among Tea Leaf Ages and Analysis Based on Microscopic Surface Features

The wettability of leaf surface, commonly represented by contact angle (CA), affects various physiological and physical processes. The present study aims to better understand the wettability of tea leaves and elucidate its influence on the energy barrier of the droplet condensation process. The CA values of different leaf ages (young, mature and old) of five famous tea cultivars (Maolu, longjing 43, Huangjinya, Zhongcha 108 and Anji Baicha) were measured via the sessile drop method, and the micro-morphology of two cultivars leaves (Maolu, Zhongcha 108) was investigated by a 3D super depth-of-field digital microscope. Specifically, two radically distinctive types of CA trends were observed, one was the decreased firstly and then increased slightly with the increase of leaf age, while the other stayed constant. The valley depth or maximum height (RZ) of Maolu leaf surface increased with the leaf age while the RZ of Zhongcha 108 leaf remained unchanged by comparing the microscopic features. The Maolu mature leaf CA decline attributed to the young leaf was hydrophilic (θ < 90°), and it was considered that surface structures like folds and pits on old leaf played a crucial role in making CA increased. Small deviation in CA can lead to significant error in calculation of the contact angle function of energy barrier in phase change. It will have great significant for simulating and better understanding the formation of frost on tea leaves.

Importance of adjuvant formulation properties in predicting wetting on leaf surfaces.

Leaf wettability can be a barrier to retention of agrichemical sprays. Adjuvants are used to modify leaf wetting by sprays to enhance retention. A previous study developed a model that accurately predicted nonadjuvant formulation wetting (contact angle) on both synthetic and leaf surfaces. Model inputs were the surface properties, roughness and polarity, as measured by the wetting tension dielectric method, coupled with the formulation properties, surface tension and dielectric constant. Preliminary work has indicated that the wetting ability of adjuvant formulations on different surfaces could be modelled in a similar way if the effect of adjuvants on solution polarity could be accurately quantified. The wetting of nine agrichemical adjuvants, at a range of concentrations, were measured on seven synthetic and 14 leaf surfaces. A novel method was developed to quantify the interfacial dielectric polarity (IDP) of adjuvant formulations. Adjuvant concentration did not change the IDP indicating the surface-active surfactant molecules migrate to the interface, loading until saturation. Formulation properties of surface tension and IDP were found to be strong predictors of wetting in conjunction with surface properties of the substrate. The previously developed unaltered comprehensive wetting model could predict the wetting of adjuvant formulations on synthetic and leaf surfaces (R2 = 0.9) using these inputs. Wetting of adjuvant formulations can be modelled for a wide range of surfaces and this model is expected to advance the selection, and development, of adjuvants to target specific surfaces generating the desired wetting outcome. © 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Importance of leaf surface and formulation properties in predicting wetting outcomes.

Leaf wettability is a major hurdle for the retention of agrichemical sprays that is combated, in part, by using adjuvant modified formulations. Scientists must understand the properties of the leaf surface and the formulation that govern wetting to intelligently select or formulate products to target specific pests. A comprehensive database comprising 11 synthetic surfaces and 54 leaf surfaces (species, adaxial and abaxial sides, cultivars, and plant age) using 35 formulations (neat solutions and adjuvants solutions at different concentrations) was compiled. Surface properties of the physical roughness and chemical polarity, as quantified by the wetting tension dielectric method, and formulation properties of surface tension and polarity, as quantified by dielectric constant, were found to govern wetting. A comprehensive wetting model was developed that employed these variables and was capable of accurately predicting the wetting outcome (R2 =0.86) on all the leaf and synthetic surfaces investigated. This model adequately predicts adjuvant formulation wetting despite exact formulation polarity being unknown. Wetting can be modelled for a wide range of surfaces and solutions. The comprehensive wetting model developed shows potential to better predict the wetting outcome of adjuvant formulations should a method to quantify the formulation dielectric constant be developed. This research provides a significant advancement in the understanding of the properties governing wetting, which may aid the selection and development of adjuvants to target specific surfaces. © 2022 Society of Chemical Industry.

The role of radiative cooling and leaf wetting in air–leaf water exchange during dew and radiation fog events in a temperate grassland

During prolonged dry periods, non-rainfall water (NRW) plays a vital role as water input into temperate grasslands, affecting the leaf surface water balance and plant water status. Previous chamber and laboratory experiments investigated air–leaf water exchange during dew deposition, but overlooked the importance of radiative cooling on air–leaf water exchange because the chamber is a heat trap, preventing radiative cooling. To complement these previous studies, we conducted a field study, in which we investigated the effect of radiatively-induced NRW inputs on leaf water isotope signals and air–leaf water exchange in a temperate grassland during the dry-hot summers of 2018 and 2019. We carried out field measurements of the isotope composition of atmospheric water vapor, NRW droplets on foliage, leaf water, xylem water of root crown, and soil water, combined with meteorological and plant physiological measurements. We combined radiation measurements with thermal imaging to estimate leaf temperatures using different methods, and computed the corresponding leaf conductance and air–leaf water exchange. Our results indicate that radiative cooling and leaf wetting induced a switch of direction in the net water vapor exchange from leaf-to-air to air-to-leaf. The leaf conductance and air–leaf water exchange varied by species due to the species-specific biophysical controls. Our results highlight the ecological relevance of radiative cooling and leaf wetting in natural temperate grasslands, a process which is expected to influence land surface water budgets and may impact plant survival in many regions in a drier climate.

Leaf wettability, anatomy and ultra-structure of Nothofagus antarctica and N. betuloides grown under a CO2 enriched atmosphere

Increasing CO2 air concentration may affect wettability, anatomy and ultra-structure of leaves of Patagonian forest species, evergreen and deciduous plants potentially responding differently to such CO2 increases. In this study, we analysed the wettability, anatomy and ultra-structure of leaves of Nothofagus antarctica (deciduous) and N. betuloides (evergreen) grown under high CO2 concentrations. Leaf wettability was affected by increasing CO2, in different directions depending on species and leaf side. In both species, soluble cuticular lipid concentrations per unit leaf area raised with higher CO2 levels. Stomatal parameters (density, size of guard cells and pores) showed different responses to CO2 increasing depending on the species examined. In both species, leaf tissues showed a general trend to diminish with higher CO2 concentration. Cuticle thickness was modified with higher CO2 concentration in N. betuloides, but not in N. antarctica leaves. In both species, chloroplasts were often damaged with the increase in CO2 concentration. Our results show that several surface and internal leaf parameters can be modified in association with an increase in atmospheric CO2 concentration which may very among plant species.

The detected effects of driptips and leaf wettability on the kinetic energy of throughfall in rubber‐based agroforestry in Xishuangbanna

AbstractDriptips play important roles in controlling soil erosion and in the water cycle. The driptips size distribution and the morphology of water droplets on the leaves among rubber (Hevea brasiliensis) and intercropping species (Camellia sinensis, Citrus reticulata, Flemingia macrophylla and Theobroma cacao) were measured. Driptip‐producing experiments were conducted indoors on stabilized leaves of five species with artificially mist spray. In all five foliage species, the diameter of the driptips from rubber leaves was the lowest. Furthermore, the relationship between driptips size and the mean leaf width at 3 mm from the rubber leaf tip was significantly positively correlated. Leaf wettability as measured by water droplets height linearly increase with the total volume of water which dropped on the leaves of all five species. The contact angle of the water droplets and the total volume of the droplet were significantly negatively correlated. Based on physical theory, the kinetic energy of the driptips was calculated by estimating the diameters of the driptip from all five species. The results indicated that it was important to consider the kinetic energy of driptips in selection of intercropping species when constructing rubber‐based agroforestry plantations. Understanding the relationship between driptips size and the development of leaf tips (leaf width at 3 mm from the leaf tip) will require more experiments with different leaf inclinations, and the results also confirmed that using the contact angle of water droplets to assess leaf wettability. This study can help to predict canopy water processes, such as canopy water storage and drainage.

On the role of the phyllosphere community in leaf wettability and water shedding.

We explore the interplay among factors affecting leaf wettability and water shedding by discussing how the phyllosphere directly affects plant wettability.

Preparation of an Environmentally Friendly Nano-Insecticide through Encapsulation in Polymeric Liposomes and Its Insecticidal Activities against the Fall Armyworm, Spodoptera frugiperda

Simple SummaryPests are an important factor that causes a heavy loss in corn yield and quality. The fall armyworm (FAW), Spodoptera frugiperda, is a newly invasive and extremely destructive pest, and it poses a major threat to agricultural production in China. While chemical pesticides are considered effective means for controlling the outbreak of destructive pests, pesticide delivery systems, such as microcapsules or nanoparticles, are an effective way to promote the utilization rate of traditional pesticides and to reduce environmental pollution. Therefore, the aim of this study is to design an environmentally friendly nano-insecticide that can enhance foliar retention and increase insecticidal activity. For this purpose, 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[amino(polyethylene glycol)-2000] (DSPE-PEG2000-NH2) was chosen to formulate the insecticide nanoparticles. The physicochemical properties were characterized and investigated in indoor and field efficacy trials. The results demonstrate that the nanoparticles hold promise for pest control. The insecticide emamectin benzoate (EB) was formulated with nanoparticles composed of DSPE-PEG2000-NH2 by the co-solvent method to determine its adverse impacts on the environment and to reinforce its dispersion, adhesion, and biocompatibility. A good encapsulation efficiency (70.5 ± 1.5%) of EB loaded in DSPE-PEG2000-NH2 polymeric liposomes was confirmed. Dynamic light scattering (DLS), transmission electron microscopy (TEM), and contact angle meter measurements revealed that the DSPE-EB nanoparticles had a regular distribution, spherical shape, and good leaf wettability. The contact angle on corn leaves was 47.26°, and the maximum retention was higher than that of the reference product. DSPE-EB nanoparticles had strong adhesion on maize foliage and a good, sustained release property. The efficacy trial showed that the DSPE-EB nanoparticles had a strong control effect on S. frugiperda larvae, with the LC50 of 0.046 mg/L against the third-instar S. furgiperda larve after 48 h treatment. All these results indicate that DSPE-EB nanoparticles can serve as an insecticide carrier with lower environmental impact, sustained release property, and effective control of pests.

Shoot dimorphism enables Sequoia sempervirens to separate requirements for foliar water uptake and photosynthesis.

PremiseTrees in wet forests often have features that prevent water films from covering stomata and inhibiting gas exchange, while many trees in drier environments use foliar water uptake to reduce water stress. In forests with both wet and dry seasons, evergreen trees would benefit from producing leaves capable of balancing rainy‐season photosynthesis with summertime water absorption.MethodsUsing samples collected from across the vertical gradient in tall redwood (Sequoia sempervirens) crowns, we estimated tree‐level foliar water uptake and employed physics‐based causative modeling to identify key functional traits that determine uptake potential by setting hydraulic resistance.ResultsWe showed that Sequoia has two functionally distinct shoot morphotypes. While most shoots specialize in photosynthesis, the axial shoot type is capable of much greater foliar water uptake, and its within‐crown distribution varies with latitude. A suite of leaf surface traits cause hydraulic resistance, leading to variation in uptake capacity among samples.ConclusionsShoot dimorphism gives tall Sequoia trees the capacity to absorb up to 48 kg H2O h−1 during the first hour of leaf wetting, ameliorating water stress while presumably maintaining high photosynthetic capacity year round. Geographic variation in shoot dimorphism suggests that plasticity in shoot‐type distribution and leaf surface traits helps Sequoia maintain a dominate presence in both wet and dry forests.

Leaf surface traits contributing to wettability, water interception and uptake of above-ground water sources in shrubs of Patagonian arid ecosystems.

The ecohydrological significance of leaf wetting due to atmospheric water in arid and semiarid ecosystems is not well understood. In these environments, the inputs of precipitation or dew formation resulting in leaf wetting have positive effects on plant functioning. However, its impact on plant water relations may depend on the degree of leaf surface wettability. In this study we evaluated leaf wettability and other leaf traits and its effects on foliar water uptake and canopy interception in plant species of a Patagonian steppe. We also studied how leaf traits affecting wettability vary seasonally from growing to dry season. Contact angle of a water droplet with the leaf surface, water adhesion, droplet retention angle, stomatal density, cuticular conductance, canopy interception and maximum foliar water uptake were determined in six dominant shrub species. All species increased leaf wettability during the dry season and most species were considered highly wettable. The leaf surface had very high capacity to store and retain water. We found a negative correlation between foliar water uptake and leaf hydrophilia. Despite the diversity of life forms, including cushion shrubs and tall shrubs, as well as phenological variability, all species converged in similar seasonal changes in leaf traits that favour wettability. Intercepted water by crowns and the extremely high capacity of retention of droplets on leaf surfaces can have a significant impact on eco-hydrological process in water limited ecosystems where most of water sources during the growing and the dry season may be small rainfall events or dew, which do not always increase soil water availability.

Species-specific dynamics in magnetic PM accumulation and immobilization for six deciduous and evergreen broadleaves

Numerous studies have demonstrated the effectiveness of plants in accumulating airborne particulate matter (PM) on their leaf surfaces. However, it is not fully clear whether leaf traits or atmospheric conditions influence the accumulation and immobilization dynamics of magnetic PM on leaf surfaces. In this study, leaves of two deciduous broadleaf trees (Quercus petraea, Quercus robur), two deciduous broadleaf shrubs (Prunus padus, Sambucus nigra) and two evergreen broadleaf shrubs (Prunus laurocerasus, Rhododendron sp.) were sampled from a common garden every 48 to 72-h to determine the dynamics of magnetic PM accumulation and immobilization. The mass of water-insoluble removable PM was estimated using gravimetric analysis. The ferro-magnetic and magnetizable component of leaf surface accumulated PM, leaf immobilized PM and water-insoluble removable PM in three size fractions (PM > 10, 3–10, and 0.2–3 μm) was determined using Saturated Isothermal Remanent Magnetization (SIRM). Leaf SIRM for both surface accumulated PM and leaf immobilized PM differed in the following order Q. robur < Q. petraea < S. nigra < P. laurocerasus < P. padus < Rhododendron sp. indicating that PM immobilization on leaves of plant species is a function of net accumulated PM. In proportion to the SIRM signal of leaf surface accumulated PM, on average 4 % was recovered in the SIRM of the water-insoluble removable PM and 63 % was found in the SIRM signal of the immobilized PM while 33 % of the SIRM signal of the leaf surface accumulated PM could not be recovered in the immobilzed or water-insoluble removable PM. The leaf surface accumulated SIRM related with leaf wettability. The mass and SIRM of water-insoluble removable PM were significantly affected by leaf traits and meteorological conditions i.e., (i) negatively by leaf wettability, precipitation and wind speed and (ii) positively by relative humidity and ambient PM2.5 concentrations. These results indicate that magnetic PM accumulation is influenced by both the atmospheric conditions as well as by the micro-morphological leaf traits of plant species. Leaves of Rhododendron sp. followed by Q. robur showed the highest median net deposition velocities for both coarse and fine-particles. Based on the results of this study we recommend S. nigra a deciduous broadleaf shrub species, as a preferred choice to mitigate PM pollution in urban environments. As it accumulated the highest proportion of ferro-magnetic particles in the mass of water-insoluble removable PM considering the harmful effects of these particles on human health. In addition, S. nigra is known to have low biogenic volatile organic compound (BVOC) emissions and provides a good provision for birds and insects.

Leaf surface traits related to differential particle adsorption – A case study of two tropical legumes

We aimed to test a set of epidermal traits in two legume species with contrasting chemical, physical, and micromorphological leaf-surface features to assess which ones would determine higher PM retention. For that, we performed a biomonitoring study in southeastern Brazil at the Steel Valley Metropolitan Region, where there is predominance of steel industry and one of the largest vehicle fleets in the country. A reference station was installed at a neighboring park. We evaluated leaf-surface roughness at two hierarchical levels, leaf wettability, epidermal-cell anticlinal-wall undulation, epidermal-cell perimeter, and the micromorphology and chemical composition of epicuticular waxes. Particle retention was significantly higher in Paubrasilia echinata than in Libidibia ferrea var. leiostachya, the former of which has lower roughness given by both the epidermal tissue (macro-roughness; 0.6 vs 2.6 μm) and epicuticular waxes (micro-roughness; 68 vs 220 nm), higher leaf wettability (82° vs 143°), lower epidermal-cell undulation index (1.2 vs 1.8), lower epidermal-cell perimeter (93 vs 146 μm), wax deposition in the form of a smooth layer (as opposed to densely aggregated rosettes of vertical platelets), and more polar wax chemical constitution (68% vs 47% of polar compounds). While all of the assessed traits contributed to particle retention, canonical loadings revealed that macro-roughness was the trait that contributed the most to the retention of PM2.5 (ca = 1.47; r = −0.56), PM10 (ca = 1.08; r = −0.61), PM100 (ca = −4.95; r = −0.39) and TSP (ca = 0.98; r = −0.62), although this trait was shown by factor analysis to be secondary in distinguishing between species (0.92 contribution to the second axis). Our findings shed new light on the criteria that should be considered when selecting species for green infrastructure aiming to reduce urban air pollution, as well as on novel possibilities for PM biomonitoring in the tropics.

Leaf surface influence on potential water use in desert plants

Water use in plants is complex with varied strategies, depending on species type and environmental conditions. The leaf surface wettability determines the spread of water droplets, with implications for water use. We examined the degree of leaf wettability and its persistence, by measuring the dynamic contact angle, base diameter, and volume of water droplets placed on the surface of three desert plant species, Artemisia sieberi, Salsola inermis, and Haloxylon scoparium. Leaf roughness was highly correlated to the amount of wax that was detected; the highest level was on S. inermis, which was 50% rougher than H. scoparium and A. sieberi. In addition, the water droplet contact angles on the A. sieberi leaf surface were more dynamic than on the other two species, starting at a high degree and then markedly decreasing, along with decreases in the volume and the base diameter; this implies absorption of the water drop, possibly due to the trichomes on the leaves. Droplets on both S. inermis and H. scoparium had a stable base diameter and showed only a slight decrease in volume, indicating no absorption. The various leaf surface characteristics determined the spread of water droplets on the leaf, presenting implications for leaf water absorption.

Limiting factor of dew formation changes seasonally in a semiarid crop field of northwest China

Understanding how seasonal and annual variations in dew formation are controlled by environmental elements of a crop field is necessary for utilizing dew as a water resource for agricultural production. Radiative cooling intensity, wind speed, and water vapor pressure are the key environmental elements for the dew formation. However, a detailed investigation of how seasonal and annual variations in these environmental elements affect the variation in dew formation is unexplored. We examined the relationship between dew characteristics (frequency, amount, and duration) and environmental elements of a semiarid crop field during the cultivation period of corn (April–September) for three years. In spring (April–June), though large nighttime negative net radiation, which indicates strong radiative cooling intensity, was observed, dew rarely occurred and only in small amounts. Conversely, in summer (July–September), dew frequently occurred and in larger amounts despite the lower radiative cooling intensity. In spring, lower water vapor pressure was observed, and thus dew formation was limited by the lack of water source of dew. In summer, water vapor pressure was high, and dew formation was predominantly limited by the radiative cooling intensity. The dew amount during the cultivation period accounted for 5.4% of the rainfall amount on average over the 3 years. However, dew occurred more frequently than rainfall at 53% of the days comprising the cultivation period. Additionally, the occurrence of dew wet the leaves for approximately 10 h indicating the significant impact of leaf wetting by dew on plant eco-physiological functions. The results of this study should advance the understanding of how dew formation is controlled by variations in the environmental elements of a semiarid crop field, which will contribute to improving the utilization of dew as a water resource for agricultural production.

Surface properties of Tetranychus urticae Koch (Acari: Tetranychidae) and the effect of their infestation on the surface properties of kidney bean (Phaseolus vulgaris L.) hosts.

The wettability of the target surfaces affects the wetting and deposition of pesticides on them. The properties of leaf surfaces change after infestation by Tetranychus urticae Koch. Studying the surface wettability of T. urticae and the changes in leaf wettability after infestation is important to guide the use of acaricides. The body surface of T. urticae is an ellipsoidal crown covered with dense cuticle striations and hairs arranged in different directions, which makes the surface of T. urticae rough and hydrophobic. The abaxial surfaces of the leaves are rougher and more hydrophobic than the adaxial surfaces. After infestation by T. urticae, the faded spots were sunken on the adaxial surface and raised on the abaxial surface, where they had formed new wide peaks and valleys. The adaxial surface became obviously rougher and more hydrophobic, while the roughness of the abaxial surface became slightly larger, and the change in hydrophobicity was not obvious. The contact angles of the studied commercial acaricide on these surfaces were greater than 65° and were affected by the infestation. Reducing the surface tension can allow for better wetting of these surfaces and eliminate changes in leaf wettability. The surfaces of kidney bean leaves became more hydrophobic after infestation by T. urticae with hydrophobic surface. The wettability of the acaricide solution should be adjusted according to the changes in leaf wettability. This study has important theoretical guiding significance for improving effective deposition of acaricide.

Roughness measurement of leaf surface based on shape from focus

BackgroundSurface roughness has a significant effect on leaf wettability. Consequently, it influences the efficiency and effectiveness of pesticide application. Therefore, roughness measurement of leaf surface offers support to the relevant research efforts. To characterize surface roughness, the prevailing methods have drawn support from large equipment that often come with high costs and poor portability, which is not suitable for field measurement. Additionally, such equipment may even suffer from inherent drawbacks like the absence of relationship between pixel intensity and corresponding height for scanning electron microscope (SEM).ResultsAn imaging system with variable object distance was created to capture images of plant leaves, and a method based on shape from focus (SFF) was proposed. The given space-variantly blurred images were processed with the proposed algorithm to obtain the surface roughness of plant leaves. The algorithm improves the current SFF method through image alignment, focus distortion correction, and the introduction of NaN values that allows it to be applied for precise 3d-reconstruction and small-scale surface roughness measurement.ConclusionCompared with methods that rely on optical three-dimensional interference microscope, the method proposed in this paper preserves the overall topography of leaf surface, and achieves superior cost performance at the same time. It is clear from experiments on standard gauge blocks that the RMSE of step was approximately 4.44 µm. Furthermore, according to the Friedman/Nemenyi test, the focus measure operator SML was expected to demonstrate the best performance.

Foliar water uptake via cork warts in mangroves of the Sonneratia genus.

Foliar water uptake (FWU) occurs in plants of diverse ecosystems; however, the diversity of pathways and their associated FWU kinetics remain poorly resolved. We characterized a novel FWU pathway in two mangrove species of the Sonneratia genus, S. alba and S. caseolaris. Further, we assessed the influence of leaf wetting duration, wet-dry seasonality and leaf dehydration on leaf conductance to surface water (Ksurf ). The symplastic tracer dye, disodium fluorescein, revealed living cells subtending and encircling leaf epidermal structures known as cork warts as a pathway of FWU entry into the leaf. Rehydration kinetics experiments revealed a novel mode of FWU, with slow and steady rates of water uptake persistent over a duration of 12 hr. Ksurf increased with longer durations of leaf wetting and was greater in leaves with more negative water potentials at the initiation of leaf wetting. Ksurf declined by 68% between wet and dry seasons. Our results suggest that FWU via cork warts in Sonneratia sp. may be rate limited and under active regulation. We conclude that FWU pathways in halophytes may require ion exclusion to avoid uptake of salt when inundated, paralleling the capacity of halophyte roots for ion selectivity during water acquisition.

Leaf prickle hairs and longitudinal grooves help wheat plants capture air moisture as a water-smart strategy for a changing climate.

The leaf features like trichome density, gradient grooves, and leaf wettability determine the efficiency to capture air moisture for self-irrigation in the wheat plant. Plants in water-scarce environments evolved to capture air moisture for their water needs either directly or indirectly. Structural features like cones, hairs, and grooves assist water capture. The morphology of crops such as wheat can promote self-irrigation under drought. To examine this further, 34 wheat genotypes were characterized for leaf traits in near optimal conditions in the field using a randomized complete block design with 3 replications. An association was found between morphological and physiological traits and yield using simple correlation plots. A core set of nine genotypes was subsequently evaluated for moisture harvesting ability and leaf wettability. Results showed that variation among genotypes exists for fog harvesting ability attributed to structural leaf features. Physiological traits, especially photosynthesis and water use efficiency, were positively associated with yield, negatively correlated with soil moisture at booting, and positively correlated with soil moisture at anthesis. The genotypes with deep to medium leaf grooves and dense hairs on the edges and adaxial surfaces (genotypes 7 and 18) captured the most moisture. This was a function of higher water drop rolling efficiency resulting from lower contact angle hysteresis. These results can be exploited to develop more heat and drought-tolerant crops.

Evaluation of the physiological significance of leaf wetting by dew as a supplemental water resource in semi-arid crop production

Dew is a frequently observed meteorological phenomenon and its importance to the water balance in arid and semi-arid regions has been recognized. The focus of our study was to evaluate the potential significance of leaf wetting by dew on semi-arid crop production in terms of its effects on plant physiological functions. We conducted a field experiment in a maizefield in northwest China. Leaf wetting by dew occurred on 45% of days during cultivation periods, and leaf water potential was higher for leaves wetted by dew than for those not wetted during the morning. In addition, we conducted a potted maize control experiment consisting of four treatments (two different soil water treatments: water-stressed and well-watered, and two different leaf wetting treatments: with and without leaf wetting). The water-stressed treatment strongly inhibited plant physiological functions (decrease in leaf water potential, stomatal closure, decrease in photosynthetic rate); therefore, growth rate decreased. However, in the water-stressed with leaf wetting plot, the maize leaves absorbed water from their surfaces during nighttime, which significantly increased pre-dawn leaf water potential. Consequently, this plot showed a higher photosynthetic rate than did the water-stressed without leaf wetting plot during daytime. The positive effects of leaf wetting on plant physiological functions were not explicit in the well-watered plots. We assumed that the positive effects of leaf wetting were mainly manifest as effects on plant–water relations; such effects may be limited when plants have sufficient water. As a result, water-stressed plants with leaf wetting showed greater water use efficiency. Our results indicate the importance of leaf wetting by dew as a water resource in semi-arid crop production owing its effects on plant physiological functions.