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Abstract Hitherto, the rapid and nondestructive determination of the moisture content of tea leaves is still an unresolved issue because the upward facing surfaces of tea leaves lying on a conveyor belt are randomly chosen by the collapse of the leaves onto their front side or back side. To study the above issue, hyperspectral images of both the front side and back side of tea leaves on a conveyor belt were captured in the lab to simulate a practical production environment, and LS-SVR models with R v 2 values of 0.951 and 0.918 for the front side and back side, respectively, were established based on their characteristic spectral bands. To ensure that the spectrum of each pixel can be correctly imported into its corresponding model, a logistic regression classifier with a correct classification rate of 100% was designed to identify the front side and back side of the leaves. Finally, a distribution map of the moisture content of the tea leaves was generated successfully according to the following steps: (1) Extracting the average spectrum of each leaf; (2) Identifying which side of the leaf the spectrum belongs to; (3) Importing the adjusted spectrum of each pixel into its corresponding regression model; and (4) Generating a distribution map of the moisture content. This research creatively provides a scheme for detecting the moisture content of tea leaves. Highlights • Establish regression and classification models for different sides of tea leaves. • Achieve the visualization of moisture content of tea leaves on different sides. • Provide an automatic moisture content detection scheme for stacked tea leaves. [ABSTRACT FROM AUTHOR]

Highlights • Chlorate uptake varied depending on the type of cut product. • Chlorate uptake increased when the cut size increased. • Chlorate uptake increased when the hydration status decreased. • Chlorate uptake increased when the washing time increased. • Chlorate uptake increased when the chlorate present in the wash water increased. Abstract During the processing of fresh produce, washing with chlorinated water may result in an unacceptable source of chlorate as a disinfection by-product (DBP) in the finished product. The differential ability for the uptake of chlorate by different fresh-cut products during washing was evaluated. Results showed that chlorate uptake was affected by the type of produce, with shredded carrots showing greater chlorate uptake than baby leaves or chopped lettuce which had intact epidermis. Among leafy vegetables, baby leaves showed greater chlorate uptake than chopped lettuce due to anatomical differences that promoted the uptake of chlorate via leaf surface. Baby leaves were characterized by a high leaf area/weight ratio, high stomatal density and intercellular spaces. Moreover, the chlorate uptake was greater when increasing the cut grade, being greater in shredded than in chopped or large cut lettuce as well as it was greater in shredded carrots than in discs or sticks. Results in baby leaves showed also that lower leaf water content and longer washing time increased chlorate uptake significantly. Chlorate uptake showed a linear response with the chlorate content present in the wash water, without a saturation effect for the tested concentrations and types of produce. In conclusion, the uptake of chlorate expressed in % with respect to the content in wash water was affected by the type of produce and cut piece size with a greater ability for the accumulation in shredded carrots followed by baby leaves and shredded lettuce. [ABSTRACT FROM AUTHOR]

Highlights • The leaf senescence models are improved by incorporating effects of leafy season climate. • Leafy season thermal and moisture conditions are major climate drivers in addition to autumn temperature and photoperiod. • Local adaptation of leaf senescence cannot be detected by current process-based models. • Climatic effects might be stronger than genetic effects. Abstract Current process-based models of autumn phenophases are generally based on autumn temperature and/or photoperiod cues. The dependence of autumn phenology on environmental conditions occurring throughout the leafy season has been overlooked. In this study, we incorporated the effect of leafy season temperature and precipitation in process-based models with the aim to improve the modelling of autumn phenology. We tested the ability of three existing and three new autumn phenology models in predicting the occurrence of leaf coloration of four deciduous tree species during 1981–2012 across temperate China. The results show that the models taking the effects of both the leafy season temperature and low precipitation into account performed best over both calibration and validation data. Compared with existing autumn phenological models, the best models predict that the potential delay of autumn phenology in a warmer world is modulated by the impact of leafy season climate on leaf senescence in a complex way: increased leafy season temperature tends to hasten the occurrence of leaf coloration while low leafy season precipitation tends to delay it. Additionally, we tested the hypothesis of a local adaptation of tree phenology through the evaluation of site-specific model parameterizations. Local fittings of the critical temperature sums in all models did not improve the model ability to simulate the occurrence of leaf coloration, which suggests either that local adaptation of leaf senescence process is virtually non-existent across the populations considered or that the genetic variation of leaf coloration traits among populations cannot be detected by our models. Our findings highlighted the importance of leafy season climate in autumn phenology modelling and its possible offset effect in the response of autumn senescence to future warming. [ABSTRACT FROM AUTHOR]

Quantity, characteristics, and energy content in sugarcane trash of six different indigenous sugarcane varieties were computed for their possible utilization. Results revealed that the total sugarcane trash weight percentage was 24.0% of the total sugarcane crop. Among all examined varieties, variety 240 produced the highest and the variety HS12 the lowest percentage of sugarcane trash with 28% and 18.6% respectively. Moisture and ash content were found less in brown leaves and more in the tops of sugarcane trash parts. The fixed carbon values in brown leaves, green leaves, and tops of the variety Thatta10 were the highest found, with 18.4%, 15.5%, and 17.3% respectively. Carbon element's percentage in brown leaves of variety HS12 was the highest with 50.0% and in Thatta10 was the lowest with 43.4%. Highest heating value was found in Thatta10 with 16.0MJ/kg, which is close to the literature reported values. [ABSTRACT FROM AUTHOR]

Contents Summary 1156 I. Introduction 1156 II. How often are leaves wet? 1157 III. The costs of leaf wetting 1157 IV. The real and potential benefits of leaf wetting 1161 V. Wet leaves: costs, benefits and tradeoffs in a changing world 1165 Acknowledgements 1166 References 1166 Summary: An often‐overlooked feature of all plants is that their leaf surfaces are wet for significant periods over their lifetimes. Leaf wetting has a number of direct and indirect effects on plant function from the scale of the leaf to that of the ecosystem. The costs of leaf wetting for plant function, such as the growth of pathogens and the leaching of nutrients, have long been recognized. However, an emerging body of research has also begun to demonstrate some very clear benefits. For instance, leaf wetting can improve plant–water relations and lead to increased photosynthesis. Leaf wetting may also lead to synergistic effects on plant function, such as when leaf water potential improvements lead to enhanced growth that does not occur when plant leaves are dry. We identify important reasons why leaf wetting can be critical for plant sciences to not only acknowledge, but also directly address, in future research. To do so, we provide a framework for the consideration of the relative balance of the various costs and benefits resulting from leaf wetting, as well as how this balance may be expected to change given projected scenarios of global climate change in the future. [ABSTRACT FROM AUTHOR]

The stage of maturity for Orthosiphon aritatus (OA) leaves revealed that stage I (young leaves) provided the highest bioactive compounds. Vacuum blanching (VB) for 75 s gave the highest sinensetin (28.4% increment) and eupatorin (21.0% increment) compared with heated water blanching (HWB). The modified Henderson model was the most suitable desorption isotherm model for the OA leaves. The VB and unblanched OA leaves were dried by different drying methods, including convection tray drying (CTD, 40-60°C), heat pump dehumidify drying (HPD, 40-60°C), mixed mode solar drying (64.6°C), and freeze-drying. Three-parameter model (TP) was the best model to explain all drying curves. The drying constant, K in the TP and activation energy were fitted to the Arrhenius model. Effective moisture diffusivities were increased with the VB, drying temperatures, and HPD. The highest specific moisture extraction rate was obtained from the VB and dried in the HPD at 60°C. The quality aspects of sinensetin (10.2% retention), eupatorin (10.7% retention), total phenolics, and antioxidant activity revealed the best quality for the OA leaves pretreated by the VB and dried in the HPD at 60°C and could reduce drying time by 44.8% compared with the CTD. The VB of the OA leaves and dried using the HPD at 60°C were recommended. [ABSTRACT FROM AUTHOR]

Moisture content is considered one of the most important quality parameters in wood fuels. In this context, natural drying is a cheap and easy method to reach adequate moisture content in forest biomass. The objective of this study is to evaluate the effect of different treatments feasible to be applied operationally in the natural drying of whole small trees. Whole trees from natural regeneration of Acacia melanoxylon with diameters of 3 to 12 cm were used in this research, in Los Ríos Region, Chile. Trees were stacked into piles outside the forest between January and December 2012, distributed in 12 biomass piles. Piles were evaluated at two heights (one and two meters), and two protection levels (without protection and using a semi-permeable cover). A factorial design with three repetitions per treatment was used. Indirect measurements of moisture content were obtained by monthly weight records. These were used to model the progress of drying in each pile. The overall effect of treatments was evaluated with factorial variance analysis using the GLM procedure. For the study conditions, results indicate that natural biomass drying has a strong seasonal component. Consequently the use of cover was essential in winter season. During summer months the cover was not necessary, being able to reach moisture content lower than 30% after the summer if storage started in the beginning of January. In this case, better results were obtained with the two-meter-high piles because they were less sensitive to occasional summer rains. [ABSTRACT FROM AUTHOR]

The study aims to track the dynamics of the olive leaf nitrogen (N), phosphorus (P) and potassium (K) for five olive varieties under drip irrigation in farmer's fields in central Morocco. Leaf sampling was done every month from May 2014 to April 2015. Leaf macronutrients contents showed variation over time. Olive leaves have maintained the same N content throughout the study period indicating a continuing olive uptake of nitrogen. Higher leaf P absorption was observed during flowering and fruit magnification periods indicating the important P needs of olive during these periods. Olive leaf K levels were higher from September to December indicating the high K needs of olive. No variety effect was revealed on the leaf N, P and K contents. Very highly significant differences were found between the leaf N and K levels measured at different sampling periods. The leaf P concentration was statistically equal in all measuring periods. [ABSTRACT FROM AUTHOR]

Abstract: Fast and effective visualization research of leaf lettuce leaves was particularly important in modern fine agriculture irrigation. Therefore, hyperspectral imaging technology was used to test the moisture content in leaf lettuce sample. A method involving wavelet transform coupled with partial least squares regression (WT‐PLSR) was proposed to extract characteristic wavelengths, build models, and evaluate characteristic wavelengths. Hyperspectral imaging data of 200 leaf lettuce leaves of five moisture gradients were obtained using hyperspectral imaging instrument. The whole region of leaf lettuce sample was selected as region of interest (ROI) to extract the hyperspectral data using sheffield index, image segment, and masking. To reduce noise interference, Savitzky–Golay (SG) algorithm was used to manage spectral data. Besides, WT‐PLSR algorithm was used to select effective feature wavelengths, build detection model, and evaluate characteristic wavelengths. The best prediction model of moisture content in leaf lettuce sample was PLSR model (RMSEP = 0.1688, R p 2=0.8307) building by characteristic wavelength extracted from fourth layers of wavelet decomposition, and it was applied to achieve the distribution of moisture content in leaf lettuce leaves. Hyperspectral imaging technology coupled with WT‐PLSR algorithm can effectively realize the quantitative detection of moisture content in leaf lettuce sample, and visualizing distribution map of moisture content in leaf lettuce leaves offered a more intuitive and comprehensive assessment of moisture contents. Practical applications: Well understanding moisture content in leaf lettuce leaves is very important for revelation of novel biological function and calcium (Ca) content. To facilitate more intuitively and comprehensively detect the moisture content in leaf lettuce leaves, a method involving wavelet transform coupled with partial least squares regression (WT‐PLSR) was proposed to extract characteristic wavelengths, build models, and evaluate characteristic wavelengths. It confirms that the WT‐PLSR algorithm is feasible and effective for building models of different moisture contents in leaf lettuce leaves, and visualizing distribution map of leaf lettuce leaves offered a more intuitive and comprehensive assessment of moisture contents. [ABSTRACT FROM AUTHOR]

Abstract: The effect of processing on the biochemical contents of Acanthus montanus leaves was investigated. The moisture, crude protein, lipid, fiber, ash, and total carbohydrate contents of the raw vegetable were 59.15, 1.85, 2.32, 3.76, 2.04, and 34.65 g/100 g, respectively. The saponin, alkaloid, tannin, flavonoid, phenol, and anthocyanin contents of the raw vegetable were 5.35, 4.04, 1.10, 3.53, 2.87, and 1.27 g/100 g, respectively, while it contained 2.65 mg/100 g calcium, 1.14 mg/100 g magnesium, 7.66 mg/100 g potassium, 350.75 μg/g vitamin A, 50.87 mg/100 g vitamin C, and 0.25% titratable acidity. There were significant reductions (p < .05) in the protein, lipid, fiber, ash, saponin, alkaloid, tannin, phenol, anthocyanin, calcium, magnesium, potassium, vitamin A, vitamin C, and titratable acidity of the boiled or boiled + sun‐dried A. montanus leaves; significant elevation of the moisture contents but significant reduction of the total carbohydrate contents of the boiled; and significant reduction of the moisture contents of the boiled + sun‐dried vegetable compared with the raw. There were significant increases (p < .05) in the total carbohydrate contents of the boiled + sun‐dried leaves; significant reductions (p < .05) in the moisture, saponin, alkaloid, and vitamins A and C contents of the sun‐dried vegetable; and no significant differences (p > .05) in the lipid, calcium, potassium, and ash, but significant increases (p < .05) in the protein, crude fiber, total carbohydrates, tannins, flavonoids, phenols, anthocyanin, magnesium, and titratable acidity of the sun‐dried vegetable when compared with the raw. Sun drying alone either retained or enhanced the release of some important bioactive compounds in A. montanus leaves. Furthermore, the reduced moisture content of the sun‐dried vegetable together with its increased titratable acidity will make the sun‐dried vegetable uninhabitable for microorganisms, thereby increasing its shelf life. [ABSTRACT FROM AUTHOR]

High productivity of fertilized loblolly pine ( Pinus taeda L.) plantations in the southern United States is related to increased leaf area index (LAI), but higher evaporative leaf surface area may increase drought vulnerability. To determine if the benefits of fertilization are affected by water availability or the effects of drought are exacerbated by fertilization, the interactive effects of throughfall treatment (ambient throughfall versus throughfall reduction) and fertilization treatment (no fertilization versus one-time fertilization) on a loblolly pine plantation were examined over five growing seasons. Enhancement of LAI and growth from fertilization was unaffected by throughfall treatment, and reductions in LAI, tree height, and stand volume increment in response to throughfall reduction were unaffected by fertilization treatment. Leaf-level stomatal conductance ( gS) was decreased and water use efficiency was increased by fertilization and by throughfall reduction. Lower gS was associated with decreased leaf predawn water potential in response to throughfall reduction. In contrast, lower gs in response to fertilization was associated with a reduction in the hydraulic allometry index, a measure of the ability of sapwood to supply water to leaves. These results suggest that fertilization may enhance LAI and growth even under mild or moderate drought. [ABSTRACT FROM AUTHOR]

Grapevine water status is critical as it affects fruit quality and yield. We assessed the potential of field hyperspectral data in estimating leaf water content ( C w ) (expressed as equivalent water thickness) in four commercial vineyards of Vitis vinifera L. reflecting four grape varieties (Mencía, Cabernet Sauvignon, Merlot and Tempranillo). Two regression models were evaluated and compared: ordinary least squares regression (OLSR) and functional linear regression (FLR). OLSR was used to fit C w and vegetation indices, whereas FLR considered reflectance in four spectral ranges centred at the 960, 1190, 1465 and 2035 nm wavelengths. The best parameters for the FLR model were determined using cross-validation. Both models were compared using the coefficient of determination ( R 2 ) and percentage root mean squared error ( %RMSE ). FLR using continuous stretches of the spectrum as input produced more suitable C w models than the vegetation indices, considering both the fit and degree of adjustment and the interpretation of the model. The best model was obtained using FLR in the range centred at 1465 nm ( R 2 = 0.70 and %RMSE = 8.485). The results depended on grape variety but also suggested that leaf C w can be predicted on the basis of spectral signature. [ABSTRACT FROM AUTHOR]

In this study, Moringa leaves were processed in two steps (1) drying and (2) grinding. In the first step, leaves were dried with different drying treatments including conventional, laboratory and advanced methods to optimize drying conditions in terms of maximum nutrients preservation and color quality. During the second step, leaves were ground with three different grinding mills including hammer, dry, and cutter mills to study the effect of grinding mechanism in combination with particles size and moisture content on the flowability of the powder. The flowability was measured using conventional and advanced methods including Carr Index and Cohesion Index. Oven drying at 50 °C was found to be the optimum conditions in terms of maximum nutrients and color preservation of Moringa leaves. The grinding mechanism having a substantial impact on the flowability of the powder produced in different types of mills. The effect of moisture content and particle size on Moringa leaves powder was also investigated and found that moisture content directly affects the flowability of Moringa leaves powder followed by particles size and shape. We have also noted powder sample prepared by the impact mechanism (hammer mill) with particle size 50 µm and moisture content 5% having appreciable flowability as compared to the samples processed by cutting (dry mill) and shattering (cutter mill) mechanisms. This study conveys an ultimate understanding regarding processing (drying and grinding) of Moringa leaves powder. Practical Applications Dried Moringa is restricted to use as dietary purposes because of its unpleasant taste, which becomes further bitter after drying procedure. Therefore, powder of Moringa leaves can be processed into different forms such as tablet, capsules and cereal formulations. For this purpose, a comprehensive study has been carried out to increase the understanding of drying and flow characteristics of Moringa (leaves and powder) using different drying and grinding mechanisms. The findings of this study regarding drying treatments, nutrients preservation, flowability and different grinding mechanisms can also be applied to other herbs and leaves. A correlation between Carr Index and Cohesion Index established successfully. This study will be helpful to conduct further research in food processing because Carr Index is simple and easy to measure as compared to Cohesion Index that requires both texture and powder flow analyzers. [ABSTRACT FROM AUTHOR]

BACKGROUND Leaf surfaces can have similar wettability, while their roughness and polarity may be very different. This may affect agrochemical bioefficacy, hence there is a need to characterise leaf surface polarity and roughness separately. This paper reviews established surface evaluation techniques and then uses a comprehensive dataset of static contact angles (12 chemical solutions on 15 different species) to compare and contrast them for their ability to characterise leaf surface polarity in isolation from roughness. RESULTS Many techniques were severely limited when applied to leaf surfaces. A failing of the surface free energy ( SFE) concept is that both physical and chemical properties affect the SFE. Additionally, whilst the leaf surface chemistry does not change, the SFE values generated are dependent on the chemical properties of the probe solution employed. CONCLUSIONS The wetting tension-dielectric ( WTD) method stands out due to its ability to isolate and quantify leaf surface roughness and polarity. A novel ( WTD) roughness correction factor is proposed to improve SFE determination. The strong correlation between leaf polarity and leaf wettability for polar solutions (such as water) makes the WTD method a valuable tool for the evaluation of leaf surface-droplet behaviour and the advancement of agrochemical spray formulation technologies. © 2017 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Background and aims: Nitrogen (N) is often the nutrient limiting the decomposability of shoots from macrophytes in wetlands. We aimed to determine the effects of increasing soil N availability on the decomposition of shoots during the standing-dead phase. Methods: We measured the quality of senesced leaves from graminoids and their subsequent aerial decay under different N addition treatments (Control, 0 kg N ha yr.; N60, 60 kg N ha yr.; N120, 120 kg N ha yr.; N240, 240 kg N ha yr.) in a temperate marsh. Results: Nitrogen addition increased N concentrations in senesced leaves and often increased phosphorus (P) concentrations. The exponential decay constants ( k) of leaves from the N120 and N240 treatments were higher than the control treatment during aerial decay. Nitrogen amounts (in percentage terms) remaining in decaying leaves always significantly decreased after N addition, but the effects on P amounts varied with N addition rates. The nutrient amounts remaining in leaves during the standing-dead phase had negative relationships with the initial nutrient concentrations. Conclusions: Soil N availability exerts remarkable effects on the decay process of standing litters by altering the initial quality, and thus the biogeochemical cycling in temperate wetlands. [ABSTRACT FROM AUTHOR]

A common approach for estimating fluxes of CO2 and water in canopy models is to couple a model of photosynthesis ( An) to a semi-empirical model of stomatal conductance ( gs) such as the widely validated and utilized Ball-Berry (BB) model. This coupling provides an effective way of predicting transpiration at multiple scales. However, the designated value of the slope parameter ( m) in the BB model impacts transpiration estimates. There is a lack of consensus regarding how m varies among species or plant functional types (PFTs) or in response to growth conditions. Literature values are highly variable, with inter-species and intra-species variations of >100%, and comparisons are made more difficult because of differences in collection techniques. This paper reviews the various methods used to estimate m and highlights how variations in measurement techniques or the data utilized can influence the resultant m. Additionally, this review summarizes the reported responses of m to [CO2] and water stress, collates literature values by PFT and compiles nearly three decades of values into a useful compendium. [ABSTRACT FROM AUTHOR]

Distinguishing meteorological and plant-mediated drivers of leaf water isotopic enrichment is prerequisite for ecological interpretations of stable hydrogen and oxygen isotopes in plant tissue. We measured input and leaf water δ2H and δ18O as well as micrometeorological and leaf morpho-physiological variables along a vertical gradient in a mature angiosperm (European beech) and gymnosperm (Douglas fir) tree. We used these variables and different enrichment models to quantify the influence of Péclet and non-steady state effects and of the biophysical drivers on leaf water enrichment. The two-pool model accurately described the diurnal variation of leaf water enrichment. The estimated unenriched water fraction was linked to leaf dry matter content across the canopy heights. Non-steady state effects and reduced stomatal conductance caused a higher enrichment of Douglas fir compared to beech leaf water. A dynamic effect analyses revealed that the light-induced vertical gradients of stomatal conductance and leaf temperature outbalanced each other in their effects on evaporative enrichment. We conclude that neither vertical canopy gradients nor the Péclet effect is important for estimates and interpretation of isotopic leaf water enrichment in hypostomatous trees. Contrarily, species-specific non-steady state effects and leaf temperatures as well as the water vapour isotope composition need careful consideration. [ABSTRACT FROM AUTHOR]

Moisture diffusivity (Dem), mass transfer coefficient (hm), activation energy and drying kinetics of the dill leaves were studied and modeled as a function of temperature (40-70 °C) and moisture content (0.20-5.67 kg water/kg dry matter). Results showed that the Dem and hm significantly depend on the temperature and moisture content ( p < 0.05). The average of Dem and hm varied between 4.02 × 10-9 to 9.65 × 10-9 m2/s, and 2.38 × 10-7 to 6.33 × 10-7 m/s, respectively. Activation energy showed a significant dependence on the moisture content and estimated as 16.84 kJ/mol for diffusion model and 28.70 kJ/mol for mass transfer model. Out of the six models considered, the logarithmic model showed the best fit to drying behavior of the dill leaves. [ABSTRACT FROM AUTHOR]

The plant economics spectrum that integrates the combination of leaf and wood syndromes provides a useful framework for the examination of species strategies at the whole-plant level. However, it remains unclear how species that differ in leaf habits and growth forms are integrated within the plant economics spectrum in subtropical forests. We measured five leaf and six wood traits across 58 subtropical plant species, which represented two leaf habits (evergreen vs deciduous) and two growth forms (tree vs shrub) in eastern China. Principal component analysis (PCA) was employed separately to construct the leaf (LES), wood (WES) and whole-plant (WPES) economics spectra. Leaf and wood traits are highly intra- and intercorrelated, thus defining not only the LES and WES, but also a WPES. Multi-trait variations in PCAs revealed that the traits which were representative of the acquisitive strategy, i.e., cheap tissue investment and rapid returns on that investment, were clustered at one end, while traits that represented the conservative strategy, i.e., expensive tissue investment and slower returns, were clustered at other end in each of the axes of the leaf and wood syndromes (PC1-axis) and the plant height strategy (PC2-axis). The local WPES, LES and WES were tightly correlated with each other. Evergreens shaped the conservative side, while deciduous species structured the acquisitive side of the WPES and LES. With respect to plant height strategies, trees formulated the acquisitive side and shrub species made up the conservative side of the WPES, LES and WES. In conclusion, our results suggested that the LES and WES were coordinated to a WPES for subtropical species. The finding of this local spectrum of plant form and function would be beneficial for modeling nutrient fluxes and species compositions in the changing climate, but also for understanding species strategies in an evolutionary context. [ABSTRACT FROM AUTHOR]

Leaf moisture content in Morus is a significant trait regulating the yield of silk production. Studies have shown that fresh leaves or leaves with high water content are preferably eaten by silk worm. Water and certain other molecules transport in plants is known to be regulated by aquaporins or Major Intrinsic Proteins (MIPs). Members of the MIP gene family have also been implicated in plant development and stress responsiveness. To understand how members of MIP gene family are regulated and evolved, we carried out an extensive analysis of the gene family. We identified a total of 36 non redundant MIPs in Morus notabilis genome, belonging to five subfamilies PIPs, TIPs, NIPs, XIPs and SIPs) have been identified. We performed a Gene ontology (GO) term enrichment analysis and looked at distribution of cis elements in their 2K upstream regulatory region to reveal their putative roles in various stresses and developmental aspects. Expression analysis in developmental stages revealed their tissue preferential expression pattern in diverse vegetative and reproductive tissues. Comparison of expression profiles in the leaves of three species including Morus notabilis , Morus serrata and Morus laevigata led to identification of differential expression in these species. In all, this study elaborates a basic insight into the structure, function and evolutionary analysis of MIP gene family in Morus which is hitherto unavailable. Our analysis will provide a ready reference to the mulberry research community involved in the Morus improvement program. [ABSTRACT FROM AUTHOR]

Leaf water content (LWC) within a plant canopy plays an important role in light penetration and scattering, thus affecting reflectance simulation with radiative transfer models. It is also of key importance for the distribution of other plant biochemical parameters, fire propagation simulation and habitat suitability evaluation. Although passive remote sensing techniques have been widely applied to estimate LWC, they are unable to retrieve the LWC vertical distribution within a canopy. In this paper we investigated the applicability of the full-waveform terrestrial laser scanning data (TLS) to estimate the LWC vertical distribution within the canopy of individual plants. A modified skewed Gaussian function that accommodates the nonlinear nature of the system was proposed to perform a decomposition on the full-waveform data. The amplitude, the backscatter cross-section, and the backscatter coefficient were assessed to estimate LWC, respectively. Our results showed that the backscatter coefficient had the strongest correlation with LWC (R 2 = 0.66) for four plant species after an incidence angle correction. Good agreements were achieved between the predicted vertical profile of LWC and the measured vertical profile of LWC with a mean RMSE (root mean square error) value of 0.001 g/cm 2 and a mean MAPE (mean absolute percent error) value of 4.46%. However, the performance of LWC vertical profile estimation varied across species, suggesting the influence of leaf structure other than LWC on waveform features, which should be considered in future studies. Nevertheless, our study successfully demonstrated the feasibility of retrieving LWC vertical distribution within plant canopy from a full-waveform terrestrial laser scanner. [ABSTRACT FROM AUTHOR]

In this study, we used visible/near-infrared (Vis/NIR) hyperspectral imaging technology to measure the reflectance and gray-level texture features of grape leaf surfaces, and we predicted water content based on those features for more effective irrigation control. Grape vine specimens were potted in the actual field environment, and five levels of water treatment with two replicates were applied to create controlled water stresses. The reflectance and gray-level co-occurrence matrix (GLCM) texture features were used to develop partial least squares (PLS) models for water content prediction. The results showed that when using both reflectance and GLCM texture features, the results achieved a correlation coefficient (rp), root mean square error of prediction (RMSEP), bias, and residual predictive deviation (RPD) of 0.900, 0.826, -2.213e-04, and 2.084, respectively. The experimental results indicated that using a Vis/NIR hyperspectral imaging system could enable this combined method of reflectance and GLCM texture to predict water content of grape vines and be beneficial for grape vine management. [ABSTRACT FROM AUTHOR]

Decreased leaf moisture content, typically measured as equivalent water thickness (EWT), is an early signal of tree stress caused by drought, disease, or pest insects. We investigated the use of two terrestrial laser scanners (TLSs) employing different wavelengths for improving the understanding how EWT can be retrieved in a laboratory setting. Two wavelengths were examined for normalizing the effects of varying leaf structure and geometry on the measured intensity. The relationship between laser intensity features, using red (690 nm) and shortwave infrared (1550 nm) wavelengths, and the EWT of individual leaves or groups of needles were determined with and without intensity corrections. To account for wrinkles and curvatures of the leaves and needles, a model describing the relationship between incidence angle and backscattered intensity was applied. Additionally, a reflectance model describing both diffuse and specular reflectance was employed to remove the fraction of specular reflectance from backscattered intensity. A strong correlation (R² = 0.93, RMSE = 0.004 g/cm²) was found between a normalized ratio of the two wavelengths and the measured EWT of samples. The applied intensity correction methods did not significantly improve the results of the study. The backscattered intensity responded to changes in EWT but more investigations are needed to test the suitability of TLSs to retrieve EWT in a forest environment. [ABSTRACT FROM AUTHOR]

Spatial and temporal variation in wet canopy conditions following precipitation events can influence processes such as transpiration and photosynthesis, which can be further enhanced as upper canopy leaves dry more rapidly than the understory following each event. As part of a larger study aimed at improving land surface modelling of evapotranspiration processes in wet tropical forests, we compared transpiration among trees with exposed and shaded crowns under both wet and dry canopy conditions in central Costa Rica, which has an average 4200 mm annual rainfall. Transpiration was estimated for 5 months using 43 sap flux sensors in eight dominant, ten midstory and eight suppressed trees in a mature forest stand surrounding a 40-m tower equipped with micrometeorological sensors. Dominant trees were 13% of the plot's trees and contributed around 76% to total transpiration at this site, whereas midstory and suppressed trees contributed 18 and 5%, respectively. After accounting for vapour pressure deficit and solar radiation, leaf wetness was a significant driver of sap flux, reducing it by as much as 28%. Under dry conditions, sap flux rates ( Js) of dominant trees were similar to midstory trees and were almost double that of suppressed trees. On wet days, all trees had similarly low Js. As expected, semi-dry conditions (dry upper canopy) led to higher Js in dominant trees than midstory, which had wetter leaves, but semi-dry conditions only reduced total stand transpiration slightly and did not change the relative proportion of transpiration from dominant and midstory. Therefore, models that better capture forest stand wet-dry canopy dynamics and individual tree water use strategies are needed to improve accuracy of predictions of water recycling over tropical forests. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The aim of this work is to determine the desorption isotherms and the drying kinetics of bay laurel leaves ( Laurus Nobilis L.). The desorption isotherms were performed at three temperature levels: 50, 60 and 70 °C and at water activity ranging from 0.057 to 0.88 using the statistic gravimetric method. Five sorption models were used to fit desorption experimental isotherm data. It was found that Kuhn model offers the best fitting of experimental moisture isotherms in the mentioned investigated ranges of temperature and water activity. The Net isosteric heat of water desorption was evaluated using The Clausius-Clapeyron equation and was then best correlated to equilibrium moisture content by the empirical Tsami's equation. Thin layer convective drying curves of bay laurel leaves were obtained for temperatures of 45, 50, 60 and 70 °C, relative humidity of 5, 15, 30 and 45 % and air velocities of 1, 1.5 and 2 m/s. A non linear regression procedure of Levenberg-Marquardt was used to fit drying curves with five semi empirical mathematical models available in the literature, The R and χ were used to evaluate the goodness of fit of models to data. Based on the experimental drying curves the drying characteristic curve (DCC) has been established and fitted with a third degree polynomial function. It was found that the Midilli Kucuk model was the best semi-empirical model describing thin layer drying kinetics of bay laurel leaves. The bay laurel leaves effective moisture diffusivity and activation energy were also identified. [ABSTRACT FROM AUTHOR]

The oxygen isotope composition of leaf water imparts a signal to a range of molecules in the atmosphere and biosphere, but has been notoriously difficult to measure in studies requiring a large number of samples as a consequence of the labour-intensive extraction step., We tested a method of direct equilibration of water in fresh leaf samples with CO2, and subsequent oxygen isotope analysis on an optical spectrometer., The oxygen isotope composition of leaf water measured by the direct equilibration technique was strongly linearly related to that of cryogenically extracted leaf water in paired samples for a wide range of species with differing anatomy, with an R2 of 0.95., The somewhat more enriched values produced by the direct equilibration method may reflect lack of full equilibration with unenriched water in the vascular bundles, but the strong relationship across a wide range of species suggests that this difference can be adequately corrected for using a simple linear relationship. [ABSTRACT FROM AUTHOR]

Resource patchiness influences consumer foraging, movement, and physiology. Fluxes across ecosystem boundaries can extend these effects to otherwise distinct food webs. Intraspecific diversity of these cross-ecosystem subsidies can have large consequences for recipient systems. Here, we show intraspecific variation in leaf defensive chemistry of riparian trees drives local adaptation among terrestrial and riverine decomposers that consume shed leaf litter. We found extensive geographic structuring of ellagitannins, diarylheptanoids, and flavonoids in red alder trees. Ellagitannins, particularly those with strong oxidative activity, drive aquatic leaf decomposition. Further, spatial variation in these leaf components drives local ecological matching: in experiments using artificial food sources distinguished only by the chemical content of individual trees, we found decomposers both on land and in rivers more quickly consumed locally derived food sources. These results illustrate that terrestrial processes can change the chemistry of cross-ecosystem subsidies in ways that ultimately alter ecosystem function in donor and recipient systems. [ABSTRACT FROM AUTHOR]

The aims of this work were (i) to study the relationships between leaf water potential, foliar chlorophyll content and photosynthetic performance of grapevines under field conditions, and (ii) to evaluate the feasibility of chlorophyll fluorescence parameters to assess water status in commercial vineyards. During three consecutive seasons (2011 to 2013), 20 non-irrigated "Tempranillo" vineyard subzones were monitored in Ribera del Duero, Spain. Data on foliar chlorophyll content, midday and predawn leaf water potential, net assimilation and chlorophyll fluorescence parameters were measured at fruit set, pre-véraison and véraison. The results show that the water potential indicated weak to moderate stress in the study years and decreased along the vegetative cycle, while foliar chlorophyll contents showed an increasing trend. The correlation between both variables was not consistent. Linear regression of the chlorophyll fluorescence parameters in dark-adapted leaves, Fo, Fv and Fv/Fm, over chlorophyll content was strong in all the study years (higher determination coefficients for Fv/Fm at fruit set in 2012 and 2013). In general, the water potential with low coefficients of variation showed a low effect on photosynthesis activity, although values in variables such as Fm, Fv, Fv/Fm, Fs/Fo and ØPSII registered an increasing trend when midday leaf water potential decreased in the pre-véraison and véraison stages. These variables could be useful to estimate water status in commercial vineyards for application in precision viticulture. [ABSTRACT FROM AUTHOR]

PREMISE OF THE STUDY: Leaves respond to environmental signals and acclimate to local conditions until their ecological limits are reached. Understanding the relationships between anatomical variation in leaves and the availability of water and light improves our ab ility to predict ecosystem-level impacts of foliar response to climate change, as it expands our knowledge of tree physiology. METHODS: We examined foliar anatomy and morphology of the largest plant species, Sequoiadendror giganteum, from leafy shoot samples collected th roughout crowns of trees up to 95 m tall and assessed the functionality of with in-crown variation with a novel drought/recovery experiment. KEY RESULTS: We found phenotypic variation in response to water availability in 13 anatomical traits of Sequoiadendron leaves. Shoot expansion was constrained by the hydrostatic gradient of maximum water potential, while functional traits supporting succulence and toughness were associated with sites of peak hydraulic limitation. Water-stress tolerance in experimental shoots increased dramatically with height. CONCLUSION: We propose a heat-sink function for transfusion tissue and uncover a suite of traits suggesting rapid hydraulic throughput and flexibility in water-stress tolerance investments as strategies that help this montane species reach such enormous size. Responses to water stress alter the amount of carbon stored in foliage and the rate of the eventual release of carbon. [ABSTRACT FROM AUTHOR]

The aim of this work was to conduct a research study of the leaf morphological traits of ten woody species that grow and develop in the Tamaulipan Thorn scrub Shrub land. Study species were Cordia boissieri, Helietta parvifolia (A.DC.), Condalia hookeri (M.C. Johnst.), Diospyros texana (Sheele), Diospyros palmeri (Eastw.), Zanthoxylum fagara (L. Sarg.), Sideroxylon celastrinum (Kunth T.D. Penn), Karwinskia humboldtiana (Schult. Zucc.), Celtis pallid (Torr.) and Celtis laevigata (Willd). Leaf morphological characteristics were leaf fresh weight (g), leaf area (cm2), leaf length (cm), leaf width (cm), petiole length (cm), total leaf length (cm), leaf dry weight (g), leaf water content (g) and specific leaf area (cm2 g-1).The results showed that the species Cordia boissieri got the highest value in all studied variables which ranged from 0.4167 g (leaf water content) to 101.4605 cm2 g-1 (specific leaf area). In contrast, the species Diospyros texana registered the lowest value in seven variables which ranged from 0.0217 (leaf water content) to 3.186 cm (Leaf total length. Correlation analysis showed highly significant relationships, both positive and negative, among studied leaf traits. [ABSTRACT FROM AUTHOR]

This study was conducted to determine the effects of arbuscular mycorrhizal (AM) inoculation on the leaf relative water content (LRWC), survival capacity, mycorrhizal dependency (MD), essential oil content and total protein content ofMelilotus officinalisgrown in a greenhouse under salinity stress. The experiment was conducted in a completely randomized factorial arrangement design using five replications. Zero (0), 50, 100, 150 and 200 mM sodium chloride (NaCl) and two AM fungal levels were applied. Control (without inoculation) and inoculated (with AM fungi) treatments were considered two mycorrhizal levels. LRWC and survival capacity values in AMMelilotus officinaliswere significantly higher than that in the non-AM-inoculated plants. Generally, MD, essential oil content and total protein content values were significantly higher in the AM-inoculatedMelilotus officinaliscompared with the non-AM-inoculated plants in all treatments. Results suggest thatMelilotus officinaliscould be used for the economic usage of the saline lands. [ABSTRACT FROM AUTHOR]

Vascular plant mortality during drought has been strongly linked to a failure of the internal water transport system caused by the rapid invasion of air and subsequent blockage of xylem conduits. Quantification of this critical process is greatly complicated by the existence of high water tension in xylem cells making them prone to embolism during experimental manipulation., Here we describe a simple new optical method that can be used to record spatial and temporal patterns of embolism formation in the veins of water-stressed leaves for the first time., Applying this technique in four diverse angiosperm species we found very strong agreement between the dynamics of embolism formation during desiccation and decline of leaf hydraulic conductance., These data connect the failure of the leaf water transport network under drought stress to embolism formation in the leaf xylem, and suggest embolism occurs after stomatal closure under extreme water stress. [ABSTRACT FROM AUTHOR]

The effects of two irrigation practices (RDI-I and RDI-II) and two bud load treatments on the yield and quality of the Kalecik Karası red wine grape variety were studied. The midday leaf water potential thresholds were used for irrigation timing, and those values were set as -10 bars until flowering, -13 bars between the berry set-veraison and the veraison-ripening periods, and -12 bars after harvest for both irrigation treatments. Water volumes applied in the irrigations of the RDI-I plots were 50% and 75% of the cumulative evaporation from a class A pan between the berry set-veraison and veraison-ripening growth stages, respectively, while those portions for the RDI-II treatment were vice versa. The effects of control (K) and two-fold increased bud loads (2K) based on mean pruning weight on the grape yield and quality were also investigated. Irrigation and higher bud load treatments considerably increased grape yield in both years of the study. The highest and lowest grape yields were obtained in the RDI-II and the nonirrigated treatments, respectively. The increase in grape yield of irrigated vines in relation to nonirrigated ones was 53.3% in the first year and 54.3% in the second year. With doubling the bud load, the achieved increases in grape yield were 37.8% and 45.1% compared to the traditional bud loads in the first and the second year, respectively. The bud load effect was more apparent for the irrigated vines compared to the rain-fed cultivation. Cluster weight was also higher for the irrigated vines. These increases can most probably be related to improved canopy development under irrigation application. The leaf stomatal conductance was higher as a consequence of the higher soil water contents in both irrigated treatments. The improved gas exchange due to the stomatal openings led to a higher leaf area index as well as an increase in grape yield of the irrigated plants. Our findings reveal that the grape yield of the Kalecik Karası grape variety can be increased with irrigation and higher bud load applications. It is also worth noting that a limited irrigation application may help to maintain a better berry quality compared to the traditional rain-fed grape cultivation. [ABSTRACT FROM AUTHOR]

Combustion characteristics of leaves fallen off ornamental trees in city and forest parks were evaluated. The moisture content of the leaves at the time of falling was between Wr = 36.1 and 46.9%. The average contents of the individual elements in the combustible material were Cdaf = 48.1%, Hdaf = 6.1%, Ndaf = 1.2%, Sdaf = 0.1%, and Odaf = 44.6%. The resulting ash from the dry leaves varied between Ad = 4.8 and 13.1%. The heat of combustion of the dry leaves was between Qs = 16,046 and 20,247 kJ.kg-1, and the lower heating value was between Qn = 13,479 and 19,120 kJ.kg-1. The results were compared with dry firewood of hard deciduous trees. The higher heating value of the dry leaves was 11.7% lower and the lower heating value was also lower by 15.1%. The decline of these basic combustion characteristics is caused mostly by its high ash content and to a smaller extent by the increased nitrogen content. [ABSTRACT FROM AUTHOR]

A physical vegetation model [the Two-Layer Model (2LM)] was applied to estimate the climate change impacts on rice leaf wetness (LW) as a potential indicator of rice blast occurrence. Japan was used as an example. Dynamically downscaled data at 20-km-mesh resolution from three global climate models (CCSM4, MIROC5, and MRI-CGCM3) were utilized for present (1981-2000) and future (2081-2100) climates under the representative concentration pathway 4.5 scenario. To evaluate the performance of the 2LM, the LW and other meteorological variables were observed for 108 days during the summer of 2013 at three sites on the Pacific Ocean side of Japan. The derived correct estimation rate was 77.4%, which is similar to that observed in previous studies. Using the downscaled dataset, the changes in several precipitation indices were calculated. The regionally averaged ensemble mean precipitation increased by 6%, although large intermodel differences were found. By defining a wet day as any day in which the daily precipitation was ≥ 1 mm day−1, it was found that the precipitation frequency decreased by 6% and the precipitation intensity increased by 11% for the entire area. The leaf surface environment was estimated to be dry; leaf wetness, wet frequency, and wet times all decreased. It was found that a decrease in water trap opportunities due to reduced precipitation frequency was the primary contributor to the LW decrease. For blast fungus, an increased precipitation intensity was expected to enhance the washout effect on the leaf surface. In the present case, the infection risk was estimated to decrease for Japan. [ABSTRACT FROM AUTHOR]

Using decade-long continuous observations of tree mortality and predawn leaf water potential (ψpd) at the Missouri Ozark AmeriFlux (MOFLUX) site, we studied how the mortality of important tree species varied and how such variations may be predicted. Water stress determined interannual variations in tree mortality with a time delay of 1 year or more, which was correlated fairly tightly with a number of quantitative predictors formulated based on ψpd and precipitation regimes. Predictors based on temperature and vapor pressure deficit anomalies worked reasonably well, particularly for moderate droughts. The exceptional drought of the year 2012 drastically increased the mortality of all species, including drought-tolerant oaks, in the subsequent year. The drought-influenced tree mortality was related to the species position along the spectrum of ψpd regulation capacity with those in either ends of the spectrum being associated with elevated risk of death. Regardless of species and drought intensity, the ψpd of all species recovered rapidly after sufficiently intense rain events in all droughts. This result, together with a lack of immediate leaf and branch desiccation, suggests an absence of catastrophic hydraulic disconnection in the xylem and that tree death was caused by significant but indirect effects. Species differences in the capacity of regulating ψpd and its temporal integral were magnified under moderate drought intensities but diminished towards wet and dry extremes. Severe droughts may overwhelm the capacity of even drought-tolerant species to maintain differential levels of water potential as the soil becomes exhausted of available water in the rooting zone, thus rendering them more susceptible to death if predisposed by other factors such as age. [ABSTRACT FROM AUTHOR]

Leaf photosynthesis relies on CO2 diffusing in while water vapour diffuses out. When stomata close, cuticle waxes on the epidermal tissues increasingly affect this diffusion. Also, changes in turgor can shrink or swell a leaf, varying the cuticle size. In this study, the properties of the cuticle were investigated while turgor varied in intact leaves of hypostomatous grape (Vitis vinifera L.) or amphistomatous sunflower (Helianthus annuus L.). For grape, stomata on the abaxial surface were sealed and high CO2 concentrations outside the leaf were used to maximize diffusion through the adaxial, stoma-free cuticle. For sunflower, stomata were closed in the dark or with abscisic acid to maximize the cuticle contribution to the path. In both species, the internal CO2 concentration was measured directly and continuously while other variables were determined to establish the cuticle properties. The results indicated that stomatal closure diminished the diffusion of both gases in both species, but for CO2 more than for water vapour. Decreasing the turgor diminished the movement of both gases through the cuticle of both species. Because this turgor effect was observed in the adaxial surface of grape, which had no stomata, it could only be attributed to cuticle tightening. Comparing calculated and measured concentrations of CO2 in leaves revealed differences that became large as stomata began to close. These differences in transport, together with turgor effects, suggest calculations of the CO2 concentration inside leaves need to be viewed with caution when stomata begin to close. [ABSTRACT FROM AUTHOR]

Leaf water isotopic composition is imprinted in several biomarkers of interest and it is imperative that we understand the isotopic enrichment of leaf water. Here, we test the effect of stomatal density and leaf water content on the oxygen isotopic composition of leaf water in transgenic Arabidopsis plants expressing different stomatal densities, and several other species showing a range of stomatal density., We grew Arabidopsis plants hydroponically and collected other species in the field. Stomatal density and leaf water content were determined for each plant. We measured transpiration and extracted leaf water for isotopic determination. Using these measurements and the current leaf water isotope model, we calculated several of the parameters related to leaf water isotopic enrichment., High stomatal density promoted leaf water isotope enrichment. No conclusion, however, can be drawn regarding the effect of leaf water content on leaf water isotope enrichment. Factors such as transpiration might mask the effect of stomatal density on leaf water isotopic enrichment., We propose a method by which stomatal density can be incorporated in the current Peclet model of leaf water isotope enrichment. These findings have important applications in the use of plant-based metabolic proxies in paleoclimate studies. [ABSTRACT FROM AUTHOR]

The water status in plant leaves is a good indicator for the water status in the whole plant revealing stress if the water supply is reduced. The analysis of dynamic aspects of water availability in plant tissues provides useful information for the understanding of the mechanistic basis of drought stress tolerance, which may lead to improved plant breeding and management practices. The determination of the water content in plant tissues during plant development has been a challenge and is currently feasible based on destructive analysis only. We present here the application of a non-invasive quantitative method to determine the volumetric water content of leaves and the ionic conductivity of the leaf juice from non-invasive microwave measurements at two different frequencies by one sensor device. A semi-open microwave cavity loaded with a ceramic dielectric resonator and a metallic lumped-element capacitor- and inductor structure was employed for non-invasive microwave measurements at 150 MHz and 2.4 Gigahertz on potato, maize, canola and wheat leaves. Three leaves detached from each plant were chosen, representing three developmental stages being representative for tissue of various age. Clear correlations between the leaf- induced resonance frequency shifts and changes of the inverse resonator quality factor at 2.4 GHz to the gravimetrically determined drying status of the leaves were found. Moreover, the ionic conductivity of Maize leaves, as determined from the ratio of the inverse quality factor and frequency shift at 150 MHz by use of cavity perturbation theory, was found to be in good agreement with direct measurements on plant juice. In conjunction with a compact battery- powered circuit board- microwave electronic module and a user-friendly software interface, this method enables rapid in-vivo water amount assessment of plants by a handheld device for potential use in the field. [ABSTRACT FROM AUTHOR]

Terahertz technology is still an evolving research field that attracts scientists with very different backgrounds working on a wide range of subjects. In the past two decades, it has been demonstrated that terahertz technology can provide a non-invasive tool for measuring and monitoring the water content of leaves and plants. In this paper we intend to review the different possibilities to perform in-vivo water status measurements on plants with the help of THz and sub- THz waves. The common basis of the different methods is the strong absorption of THz and sub-THz waves by liquid water. In contrast to simpler, yet destructive, methods THz and sub-THz waves allow for the continuous monitoring of plant water status over several days on the same sample. The technologies, which we take into focus, are THz time domain spectroscopy, THz continuous wave setups, THz quasi time domain spectroscopy and sub-THz continuous wave setups. These methods differ with respect to the generation and detection schemes, the covered frequency range, the processing and evaluation of the experimental data, and the mechanical handling of the measurements. Consequently, we explain which method fits best in which situation. Finally, we discuss recent and future technological developments towards more compact and budget-priced measurement systems for use in the field. [ABSTRACT FROM AUTHOR]

Improvement of water use efficiency is a key objective to improve the sustainability of cultivated plants, especially fast growing species with high water consumption like poplar. It is well known that water use efficiency (WUE) varies considerably among poplar genotypes, and it was recently suggested that the use of the mesophyll-to-stomatal conductance ratio (gm/gs) would be an appropriate trait to improve WUE. The responses of 7-week-old cuttings of four hybrid poplar clones and one native Balsam poplar (Populus balsamifera L.) to a water stress-recovery cycle were examined to evaluate the relation between the gm/gs ratio and transpiration efficiency (TE), a leaf-level component of WUE. A contrasting gs response to water stress was observed among the five clones, from stomatal closure early on during soil drying up to limited closure in Balsam poplar. However in the hybrids, the decline in gm was consistently delayed by a few days compared with gs. Moreover, in the most water use-efficient hybrids, the recovery following rehydration occurred faster for gm than for gs. Thus, the delay in the response of gm to drought and its faster recovery upon rewatering increased the gm/gs of the hybrids and this ratio scaled positively with TE. Our results support the use of the gm/gs ratio to select genotypes with improved WUE, and the notion that breeding strategies focusing mainly on stomatal responses to soil drying should also look for a strong curvilinearity between net carbon assimilation rate and gs, the indication of a significant increase in gm/gs in the earlier stages of stomatal closure. [ABSTRACT FROM AUTHOR]

The leaves and stem of Grewia carpinifolia were evaluated for their nutritional and anti-nutritional composition. The results showed that the leaves had significantly higher (p<0.05) crude protein (18.7±0.06%), crude fat (5.19±0.02%), ash (9.92±0.03%) and gross energy (3.32±0.01Kcal/g) than the stem having crude protein (6.90±0.03%), crude fat (1.06±0.02%), ash (2.55±0.02%) and gross energy (1.67±0.01Kcal/g), while the stem had significantly higher (p<0.05) crude fibre (25.7±0.02%) and moisture (8.40±0.01%) compared to the leaves having crude fibre (16.10±0.02%) and moisture (6.32±0.48%). The leaves recorded significantly higher values (p<0.05) for all the minerals analysed, Ca (0.26± 0.01%), Mg (0.49±0.01%), K (0.92±0.01%), P (0.42±0.00ppm), Na (0.20±0.01ppm), Se (0.0083±0.00mg/kg), Fe (192.00±0.02mg/kg), Cu (4.91±0.02) and Zn (62.10±0.02mg/kg) as against the stem. For the antinutritional factors, the leaves showed significantly higher (p<0.05) concentrations of trypsin inhibitor (3.91±0.03TIU/mg), chymotrypsin inhibitor (8.42±0.03CU/mg), haemagglutinin (25.20±0.02HU/mg), oxalate (0.95±0.01%), phytate (1.29±0.02%), tannin (0.07±0.00), flavonoids (0.004±0.00%) and phenols (0.12±0.00%), while the stem recorded significantly higher (p<0.05) levels of saponin (0.57±0.00%), alkaloids (2.33±0.01%) and glycosides (0.24±0.00%). The study concluded that the leaves of Grewia carpinifolia had generally higher nutritional quality compared to the stem due to significantly higher crude protein, crude fat, ash, gross energy and mineral contents. However, there is the need to conduct research on the in vitro digestibility and toxicity assessment of G. carpinifolia, so as to standardize and maximize its nutritional potentials. G. carpinifolia could be a rich source of proteins if its antinutritional factors are adequately processed to reduce or eliminate them. [ABSTRACT FROM AUTHOR]

Hydrogen and carbon isotope ratios of terrestrial plant leaf wax are powerful paleoclimate and paleoenvironmental proxies. However, further research on the underlying controls of the chemical and isotopic composition is needed in order to more quantitatively infer past climate and environmental conditions. There are systematic molecular and isotopic trends along leaves of a C 4 grass Miscanthus , but whether such patterns also occur in other plant types is unclear. Here we determined intra-leaf variability in leaf wax abundance and isotope ratios for five terrestrial C 3 plants. All species showed a general increasing base-to-tip trend in leaf wax abundance, suggesting a physiological need for more leaf wax in outer leaf sections. The hydrogen isotope values showed base-to-tip deuterium enrichment in all plants, but carbon isotope values showed base-to-tip 13 C depletion in most species. Such intra-leaf isotopic distributions are similar to those in the C 4 grass Miscanthus , suggesting similar underlying controls. While leaf wax hydrogen isotopic ratio values in general followed similar trends to corresponding leaf water, we found a significant reduction in hydrogen isotopic fractionation at the base of leaves (most pronounced for Dactylis glomerata ). We attribute this to the utilization of isotopically enriched glucose transported from outer leaf sections for leaf wax synthesis at the base. The transported sugars were enriched in deuterium because of preferential consumption of 2 H-depleted resources during metabolism in outer sections, in addition to biosynthesis using 2 H-enriched leaf water. [ABSTRACT FROM AUTHOR]

The relationship between stomatal conductance (gs) and leaf water potential (Ψl) is key to the understanding of plant function under changing climate. The variability among tree species gave rise to selection towards either of two contrasting water management types: isohydric or anisohydric. This study explores the variability of gs to Ψl across tree species., Curves of gs(Ψl) were collected from the scientific literature for 70 woody plant species. The data set is comprised of angiosperm and gymnosperm species from all major forest biomes. The hypothesis that curves from different tree species diverge between isohydric and anisohydric behaviours was tested., Species-specific curves formed a continuum, rather than dichotomy between isohydric and anisohydric, as confirmed by distribution models. Alternatively, the water potential at 50% of the maximum gs (Ψgs50) was used to quantitatively compare between species. A major difference emerged among xylem anatomy classes whereby ring-porous species had higher absolute gs at Ψl < −2 MPa than diffuse-porous and coniferous species. A positive, linear correlation was shown between Ψgs50 and Ψl at 50% loss of xylem conductivity., The results suggest that stomatal sensitivity to leaf water potential strongly relates to xylem characteristics. The use of Ψgs50 offers a quantitative alternative to the current, yet biased, distinction between isohydric and anisohydric species. [ABSTRACT FROM AUTHOR]

The impact of drought stress (DS) on eight Eurasian and North African genotypes of wild barley ( Hordeum spontaneum) was evaluated by analysis of chlorophyll (Chl) a fluorescence fast induction curves using the JIP-test. Three-week-old, pot-grown plants were exposed to a DS treatment by withholding water for nine days. The genotype-specific impairment of the functionality of the photosynthetic electron transport chain was quantified using the relative decline of the performance indices (PI and PI), two key parameters of the JIP-test. The genotypes showing the highest (HOR10164) and lowest (HOR10710) relative PIs under DS were subjected to additional experiments, including measurements of leaf gas exchange, water status, pigment content, key enzyme activity, and protein abundance. The genotypes showed a specific profile of DS-mediated inhibition of photosynthesis, associated with higher relative leaf water contents in HOR10164 at the end of the treatment. Whereas decreased photosynthetic rate in HOR10164 was mainly caused by stomatal closure, nonstomatal limitations (decreased Rubisco content and activity) were detected in HOR10710. Additional genotype specific features were the upregulation of the NADP-malate dehydrogenase in HOR10164 and a decreased fraction of Q-reducing reaction centers in HOR10710. [ABSTRACT FROM AUTHOR]

Atriplex ( Halimione ) portulacoides is a halophyte with potential interest for saline soil reclamation and phytoremediation. Here, we assess the impact of salinity reaching up to two-fold seawater concentration (0–1000 mM NaCl) on the plant growth, leaf water status and ion uptake and we evaluate the contribution of inorganic and organic solutes to the osmotic adjustment process. A. portulacoides growth was optimal at 200 mM NaCl but higher salinities (especially 800 and 1000 mM NaCl) significantly reduced plant growth. Na + and Cl − contents increased upon salt exposure especially in the leaves compared to the roots. Interestingly, no salt-induced toxicity symptoms were observed and leaf water content was maintained even at the highest salinity level. Furthermore, leaf succulence and high instantaneous water use efficiency (WUE i ) under high salinity significantly contributed to maintain leaf water status of this species. Leaf pressure–volume curves showed that salt-challenged plants adjusted osmotically by lowering osmotic potential at full turgor (Ψ π 100 ) along with a decrease in leaf cell elasticity (values of volumetric modulus elasticity (ε) increased). As a whole, our findings indicate that A. portulacoides is characterized by a high plasticity in terms of salt-response. Preserving leaf hydration and efficiently using Na + for the osmotic adjustment especially at high salinities (800–1000 mM NaCl), likely through its compartmentalization in leaf vacuoles, are key determinants of such a performance. The selective absorption of K + over Na + in concomitance with an increase in the K + use efficiency also accounted for the overall plant salt tolerance. [ABSTRACT FROM AUTHOR]

Main Conclusion: Modifications in leaf anatomy of tobacco plants induced greater leaf water transport capacity, meeting greater transpirational demands and acclimating to warmer temperatures with a higher vapor pressure deficit. Temperature is one of the most important environmental factors affecting photosynthesis and growth of plants. However, it is not clear how it may alter leaf hydraulic architecture. We grew plants of tobacco ( Nicotiana tabacum) 'k326' in separate glasshouse rooms set to different day/night temperature conditions: low (LT 24/18 °C), medium (MT 28/22 °C), or high (HT 32/26 °C). After 40 days of such treatment, their leaf anatomies, leaf hydraulics, photosynthetic rates, and instantaneous water-use efficiency (WUE) were measured. Compared with those under LT, plants exposed to HT or MT conditions had significantly higher values for minor vein density (MVD), stomatal density (SD), leaf area, leaf hydraulic conductance ( K), and light-saturated photosynthetic rate ( A), but lower values for leaf water potential ( ψ) and WUE. However, those parameters did not differ significantly between HT and MT conditions. Correlation analyses demonstrated that SD and K increased in parallel with MVD. Moreover, greater SD and K were partially associated with accelerated stomatal conductance. And then stomatal conductance was positively correlated with A. Therefore, under well-watered, fertilized conditions, when relative humidity was optimal, changes in leaf anatomy seemed to facilitate the hydraulic acclimation to higher temperatures, meeting greater transpirational demands and contributing to the maintenance of great photosynthetic rates. Because transpiration rate increased more with temperature than photosynthetic rate, WUE reduced under warmer temperatures. Our results indicate that the modifications of leaf hydraulic architecture are important anatomical and physiological strategies for tobacco plants acclimating to warmer temperatures under a higher vapor pressure deficit. [ABSTRACT FROM AUTHOR]

Abstract: The objective of this study was to investigate the entire spectra (from visible to the thermal infrared; 0.390–14.0μm) to retrieve leaf water content in a consistent manner. Narrow-band spectral indices (calculated from all possible two band combinations) and a partial least square regression (PLSR) were used to assess the strength of each spectral region. The coefficient of determination (R 2) and root mean square error (RMSE) were used to report the prediction accuracy of spectral indices and PLSR models. In the visible-near infrared and shortwave infrared (VNIR–SWIR), the most accurate spectral index yielded R 2 of 0.89 and RMSE of 7.60%, whereas in the mid infrared (MIR) the highest R 2 was 0.93 and RMSE of 5.97%. Leaf water content was poorly predicted using two-band indices developed from the thermal infrared (R 2 =0.33). The most accurate PLSR model resulted from MIR reflectance spectra (R 2 =0.96, RMSE=4.74% and RMSE cross validation RMSECV =6.17%) followed by VNIR–SWIR reflectance spectra (R 2 =0.91, RMSE=6.90% and RMSECV =7.32%). Using thermal infrared (TIR) spectra, the PLSR model yielded a moderate retrieval accuracy (R 2 =0.67, RMSE=13.27% and RMSECV =16.39%). This study demonstrated that the mid infrared (MIR) and shortwave infrared (SWIR) domains were the most sensitive spectral region for the retrieval of leaf water content. [Copyright &y& Elsevier]

Two contrasting responses to water stress have been reported among drought-tolerant cowpea (Vigna unguiculata L. Walp.) cultivars. In Type 1 response, growth was arrested, moisture was conserved, and the unifoliates and trifoliates desiccated at approximately the same time. In Type 2 response, the unifoliates desiccated early and leaf moisture was conserved in the trifoliates to allow growth to continue slowly for the youngest trifoliate. The objective of this study was to evaluate these contrasting responses to water stress among six previously identified tolerant and susceptible cultivars and to elucidate the physiological basis for drought tolerance in cowpea with respect to gas exchange, leaf water status, and carbohydrate partitioning. Six cultivars previously identified as differing in type and level of drought tolerance were planted in a greenhouse with drought stress initiated 11 d after planting. Gas exchange, dry weight partitioning, and water status measurements were taken on each cultivar every 3 to 5 d during water stress. Water stress reduced net photosynthesis (Anet), stomatal conductance (gsw), and transpiration, increased intercellular CO2 concentration (Ci), but had no effect on leaf water content (LWC) of the trifoliates in all cowpea cultivars regardless of the type or level of drought tolerance. Results suggest that reduced Anet under water stress was likely due to end-product inhibition rather than stomatal limitation to CO2 diffusion. This study found no evidence that the overall plant water status was improved by unifoliate senescence in certain drought-tolerant cultivars as previously postulated. Rather, this appears to be a general stress response exhibited by certain cultivars. [ABSTRACT FROM AUTHOR]