Sun Leaf Research Articles

Elevated aerosol enhances plant water-use efficiency by increasing carbon uptake while reducing water loss.

Aerosols could significantly influence ecosystem carbon and water fluxes, potentially altering their interconnected dynamics, typically characterized by water-use efficiency (WUE). However, our understanding of the underlying ecophysiological mechanisms remains limited due to insufficient field observations. We conducted 4-yr measurements of leaf photosynthesis and transpiration, as well as 3-yr measurements of stem growth (SG) and sap flow of poplar trees exposed to natural aerosol fluctuation, to elucidate aerosol's impact on plant WUE. We found that aerosol improved sun leaf WUE mainly because a sharp decline in photosynthetically active radiation (PAR) inhibited its transpiration, while photosynthesis was less affected, as the negative effect induced by declined PAR was offset by the positive effect induced by low leaf vapor pressure deficit (VPDleaf). Conversely, diffuse radiation fertilization (DRF) effect stimulated shade leaf photosynthesis with minimal impact on transpiration, leading to an improved WUE. The responses were further verified by a strong DRF on SG and a decrease in sap flow due to the suppresses in total radiation and VPD. Our field observations indicate that, contrary to the commonly assumed coupling response, carbon uptake and water use exhibited dissimilar reactions to aerosol pollution, ultimately enhancing WUE at the leaf and canopy level.

Cluster microclimate, canopy management and its influence on the berry (size and composition) quality

Sunlight and microclimate inside the clusters’ zone are key factors in berry development and must composition. Plant geometry and training system should be joined with a proper sunlight and temperature cluster microclimate and, also in the rest of the plant. Berry temperature can vary between 2 and 10 ºC or even more in inner clusters, depending on their exposure (Spayd et al., 2002). Sunlight, air ventilation within the canopy, temperature cluster and microclimate are affected by the exposure and radiation percentage received by grapes during its growth and maturation period (Deloire and Hunter 2005). In Mediterranean conditions (warm and dry climate), the use of porous systems may help plants establish a better leaf distribution inside this area (de la Fuente et al., 2015), providing more space and enhancing certain physiological processes, both in leaves (photosynthesis, ventilation, transpiration) and berries (growth and maturation). Grapes exposed to direct radiation are more sensitive to ripening and they can even suffer a dehydration process in the Mediterranean regions, where the temperature during the ripening after midday is frequently between 30-35 ºC or higher than 40 ºC (de la Fuente et al., 2015). A key point for well microclimate management inside the canopy is heat flux control, which is usually generated by three factors: surface area (SA) to PAR (direct or indirect) radiation; intensity or thermal value (related to the temperature) and time of exposure (de la Fuente, 2009; de la Fuente et al., 2013). Sprawl systems are non-positioned systems where vegetation is in multidirectional directions. Therefore, as sun position changes along the day, some leaves are first shaded and then others, so the sun leaf exposure decreases (Gutiérrez et al., 2021). The study was conducted in D.O. Uclés vineyards (lat. 39º50’8” N; long. 3º09’48.6” W; elevation 746 m above sea level) during the 2020 season, in cv. Tempranillo. The trial was designed with two training system: Vertical Shoot Positioned (VSP) and Sprawl (SP). Berry sampling was done every three days within the final 15 days before the estimated harvest date. A single sample comprised 100 berries collected from the clusters of the 10 selected vines in each block. Weight, size, must composition (reducing sugar, pH, acidity, volatile acidity, etc.) and skin composition (total and acylated monomeric pigments, TPI) were analysed. Regarding the berry composition, SP accumulated larger concentration of reducing sugars (+7.4%). No statistical differences were observed in the remaining oenological parameters measured in the berries between treatments. Nevertheless, inside total pigments and color parameters, TPI values reached significantly higher (+40%) in the SP vs VSP treatments. In the total concentration of pigments (including the acylated fraction) and pH, no differences were founded. Berry's weight and size showed some relevant differences between treatments. During the end maturity-harvest period, the berry weight (12-11%) and berry size (6-9%) were higher in SP treatment compared to VSP. These results suggest that the SP systems can induce an increment of reducing sugars, and TPI and also, can modulate the berry weight and size, helping to control overripening and berry dehydration processes. Therefore, sprawl systems (SP) represent an alternative to VSP systems in warm areas for achieving an increment of pigments, as well as for better control of the accumulation of reducing sugars, without compromising the harvest yield (higher berry weight and size).

Aerosol pollution alters the diurnal dynamics of sun and shade leaf photosynthesis through different mechanisms

Anthropogenic aerosols have been shown to perturb CO2 exchange between the vegetation and the atmosphere. However, the climate effects of aerosols through carbon cycle feedback still have significant uncertainties. Taking advantage of the periodic fluctuations of aerosol loading in Beijing, we intensively measured the diurnal course of leaf microclimates and photosynthesis under different aerosol conditions during the growing season in 2014 and 2015. We found that increasing aerosol loadings altered the diurnal course of microclimates and thus sun and shade leaf photosynthesis. Our mechanistic photosynthesis model experiments further showed that aerosol-induced increase in sun leaf photosynthesis occurred around noon and afternoon, mainly by alleviating the depression of photosynthesis caused by high leaf temperature and leaf-air vapour pressure deficit. Meanwhile, aerosols enhanced shade leaf photosynthesis throughout the day by mitigating the light limitation within the canopy, with the highest increase occurring around noon. Overall, our study suggested that aerosol's diffuse fertilization effect, cooling effect and the accompanying low leaf-air vapour pressure deficit collectively drove the changes in the diurnal courses of sun and shade leaf photosynthesis. Our results provided an important benchmark for assessing how anthropogenic aerosols regulate ecosystem C balance under different meteorological conditions.

Field evidence reveals conservative water use of poplar saplings under high aerosol conditions

Abstract Anthropogenic aerosols could alter multiple meteorological processes such as radiation regime and air temperature, thereby modifying plant transpiration. However, the lack of field observations at leaf and plant level hinders our ability to understand how aerosols could affect plant water use. Aerosol concentrations in northern China fluctuate periodically over a wide range. Taking advantage of this unique natural experiment opportunity, we conducted a series of physiological and environmental measurements at different times of the day to explore diurnal aerosols' effect on leaf transpiration and sap flow of planted poplar saplings (Populus × canadensis Moench). We found that high aerosol concentrations suppressed sun leaf transpiration by reducing leaf‐to‐air vapour pressure deficit (VPDleaf), while had no effect on shade leaf transpiration mainly because the negative effect of reduced VPDleaf on transpiration offset the positive effects of the increased stomatal conductance (gs). As aerosol concentration increased, the gs of both sun and shade leaves decreased more rapidly with an increase in VPDleaf, which caused their transpiration rates to become less sensitive to VPDleaf. Similarly, aerosols reduced sap flow density and its sensitivity to VPD. Synthesis. Our study provided observational evidence on aerosols' effects on plant transpiration at the leaf and canopy scales. The reduced transpiration and stronger stomatal control indicated that plant water use becomes more conservative under elevated aerosol concentrations.

Xeromorphic Features of the Leaves of Liriodendron Tulipifera L. (Magnoliaceae) in the Arid Climate of Central Asia

High irradiance of a habitat in arid areas is usually associated with high temperature and dry air, which can cause water deficiency in plants. The Tulip tree (Liriodendron tulipifera) is a light-loving mesophytic species. This study showed that L. tulipifera forms shade or sun leaves depending on the light conditions. Some xeromorphic features were found in leaves of the trees in illuminated habitats. These sun leaves are smaller, denser, and thicker, with smaller epidermal cells and a thick cuticle; the spongy parenchyma consists of a larger number of rows of small cells; the cells of the columnar parenchyma are larger than the shade leaves. The sun leaf contains more total chlorophyll (by 20–30%), and the guard cells of the stomata of the sun leaf contain chloroplasts. The increased concentration of chlorophyll probably maintains the energy balance in the conditions of inhibited photosynthesis under high illumination and temperature. Decreased sizes of the sun leaf and epidermis cells, thickening of the cuticle and cell wall of epidermal cells, sunken stomata, compact mesophyll with small intercellular spaces, and multirow spongy parenchyma protect from overheating and passive loss of water and can be considered as xeromorphic features. Large numerous stomata and vascular bundles contribute to effective cooling of the surface by transpiration at high temperatures under sufficient water supply. Thus, the leaves of L. tulipifera have an ecological plasticity in relation to illumination and temperature, which contributed to the acclimation of the species to the habitat conditions in arid climates.

Toward Mapping Dietary Fibers in Northern Ecosystems Using Hyperspectral and Multispectral Data

Shrub proliferation across the Arctic from climate warming is expanding herbivore habitat but may also alter forage quality. Dietary fibers—an important component of forage quality—influence shrub palatability, and changes in dietary fiber concentrations may have broad ecological implications. While airborne hyperspectral instruments may effectively estimate dietary fibers, such data captures a limited portion of landscapes. Satellite data such as the multispectral WorldView-3 (WV-3) instrument may enable dietary fiber estimation to be extrapolated across larger areas. We assessed how variation in dietary fibers of Salix alaxensis (Andersson), a palatable northern shrub, could be estimated using hyperspectral and multispectral WV-3 spectral vegetation indices (SVIs) in a greenhouse setting, and whether including structural information (i.e., leaf area) would improve predictions. We collected canopy-level hyperspectral reflectance readings, which we convolved to the band equivalent reflectance of WV-3. We calculated every possible SVI combination using hyperspectral and convolved WV-3 bands. We identified the best performing SVIs for both sensors using the coefficient of determination (adjusted R2) and the root mean square error (RMSE) using simple linear regression. Next, we assessed the importance of plant structure by adding shade leaf area, sun leaf area, and total leaf area to models individually. We evaluated model fits using Akaike’s information criterion for small sample sizes and conducted leave-one-out cross validation. We compared cross validation slopes and predictive power (Spearman rank coefficients ρ) between models. Hyperspectral SVIs (R2 = 0.48–0.68; RMSE = 0.04–0.91%) outperformed WV-3 SVIs (R2 = 0.13–0.35; RMSE = 0.05–1.18%) for estimating dietary fibers, suggesting hyperspectral remote sensing is best suited for estimating dietary fibers in a palatable northern shrub. Three dietary fibers showed improved predictive power when leaf area metrics were included (cross validation ρ = +2–8%), suggesting plant structure and the light environment may augment our ability to estimate some dietary fibers in northern landscapes. Monitoring dietary fibers in northern ecosystems may benefit from upcoming hyperspectral satellites such as the environmental mapping and analysis program (EnMAP).

Light regimen-induced variability of photosynthetic pigments and UV-B absorbing compounds in Luzula sylvatica from Arcto-Alpine tundra

The aim of this study was to evaluate the effects of different in situ light regimen on ecophysiological parameters of Luzula sylvatica leaves. Plants of L. sylvatica grown under natural sunny and shade conditions in arcto-alpine tundra were analyzed with respect to their leaf anatomy, content of photosynthetic pigments, UV absorbing compounds and phenanthrenoid compounds. Relationship between chlorophyll concentrations (Chla+b) and SPAD values was determined for sun and shade leaves measured repeatedly within summer and autumn seasons 2019 and 2020. Pooled data showed curvilinear Chla+b to SPAD relationship with the highest Chla+b and SPAD values found for shade leaves. Sun leaves had higher UV-B absorbing compounds contents than shade ones. The HPLC-DAD analysis revealed significant amount of soluble flavonoids in Luzula sylvatica leaves, amongst others the flavone-luteolin and its derivatives (e.g. tentatively identified luteolin-methyl-glucoside and luteolin-glucoside). The accumulation of luteolin based compounds in sun acclimated leaves is also plausible explanation for the higher antioxidant activity determined in sun leaf extraxts. Such response of flavonoid metabolism may help L.S. to cope with excessive-light stress through UV-attenuation mechanism and ROS scavanging. Additionally, phenanthrenoid compounds contents in L. sylvatica leaves were determined. Altogether, 9 phenanthrenoid compounds were identified by HPLC-HRMS. Their content was markedly different (up to the factor of 5) between sun and shade leaves of L.sylvatica.

Functional Crown Architecture of Five Temperate Broadleaf Tree Species: Vertical Gradients in Leaf Morphology, Leaf Angle, and Leaf Area Density

The morphology, inclination, and spatial distribution of leaves in different parts of tree crowns are important determinants of the radiation, momentum, and gas exchange between the canopy and the atmosphere. However, it is not well known how these foliage-related traits vary among species differing in successional status. We measured leaf size, leaf mass area (LMA), leaf inclination (angle to the horizontal), leaf area density (LAD), total leaf area (leaf area index, LAI), and leaf area distribution across the crown in adult trees of five common, early to late-successional tree species (Betula pendula Roth, Quercus petraea (Matt.) Liebl., Carpinus betulus L., Tilia cordata Mill., and Fagus sylvatica L.) using different canopy access techniques and the harvest of foliated trees (29 trees in total). Leaf size increased continuously with crown depth in B. pendula and T. cordata but peaked at mid-crown in Q. petraea, C. betulus, and F. sylvatica to decrease toward the shade crown. By contrast, LMA and leaf angle decreased continuously with crown depth in all species, but the pattern of vertical change varied. The mid/late- and late-successional species had higher LAI, lower shade-leaf LMA, lower leaf angles (shade and sun crown), and higher LAD in the uppermost sun crown in comparison to early successional B. pendula. We assume that the most peripheral sun leaf layer is partly acting as a shield against excess radiation, with foliage properties depending on the structure of the shade crown. We conclude that the vertical change in leaf morphology, inclination, and spatial distribution in tree crowns is highly species specific, with partial dependence on the species’ position in succession.

Sun and shade leaf variability in Liquidambar chinensis and Liquidambar formosana (Altingiaceae): implications for palaeobotany

Many factors influence leaf anatomy and morphology in the crown of a tree, particularly those resulting from microclimatic differences between the periphery and the interior of the crown. These influences can be so strong that single species can produce different leaf forms in which shade and sun leaves exhibit consistently distinctive morphological and epidermal character sets. Here we show, using Liquidambar as a model system, that the principal morphological characters for distinguishing shade and sun leaves in two modern Liquidambar spp. with different lamina types (entire in L. chinensis and lobate in L. formosana) are the leaf lamina length to width ratio, the degree of development of venation networks, tooth size and tooth shape. The main epidermal characters are ordinary cell size and anticlinal wall outlines. Many fossils, however, are only preserved as impressions and morphological characters alone have been used to distinguish shade and sun leaf morphotypes. To evaluate the utility of our approach, populations of fossil Liquidambar leaves from the Eocene of southern China, preserved only as impressions, were categorized into sun and shade morphotypes. Recognition that sun and shade leaf morphological diversity exists in fossil populations will enable palaeobotanists to identify more reliably foliar polymorphisms that would otherwise be used to describe, incorrectly, different species.

Multiangular Observation of Canopy Sun-Induced Chlorophyll Fluorescence by Combining Imaging Spectroscopy and Stereoscopy

The effect that the canopy structure and the viewing geometry have on the intensity and the spatial distribution of passively measured sun-induced chlorophyll fluorescence at canopy scale is still not well understood. These uncertainties constrain the potential use of fluorescence to quantify photosynthesis at this level. Using a novel technique, we evaluated the diurnal changes in the spatial distribution of sun-induced fluorescence at 760 nm (F760) within the canopy as a consequence of the spatial disposition of the leaves and the viewing angle of the sensor. High resolution spectral and stereo images of a full sugar beet canopy were recorded simultaneously in the field to estimate maps of F760 and the surface angle distribution, respectively. A dedicated algorithm was used to align both maps in the post-processing and its accuracy was evaluated using a sensitivity test. The relative angle between sun and the leaf surfaces primarily determined the amount of incident Photosynthetic Active Radiation (PAR), which in turn was reflected in different values of F760, with the highest values occurring in leaf surfaces that are perpendicularly oriented to the sun. The viewing angle of the sensor also had an impact in the intensity of the recorded F760. Higher viewing angles generally resulted in higher values of F760. We attribute these changes to a direct effect of the vegetation directional reflectance response on fluorescence retrieval. Consequently, at leaf surface level, the spatio-temporal variations of F760 were mainly explained by the sun–leaf–sensor geometry rather than directionality of the fluorescence emission. At canopy scale, the diurnal patterns of F760 observed on the top-of-canopy were attributed to the complex interplay between the light penetration into the canopy as a function of the display of the various leaves and the fluorescence emission of each leaf which is modulated by the exposure of the individual leaf patch to the incoming light and the functional status of photosynthesis. We expect that forward modeling can help derive analytical simplified skeleton assumptions to scale canopy measurements to the leaf functional properties.

Cell expansion not cell differentiation predominantly co-ordinates veins and stomata within and among herbs and woody angiosperms grown under sun and shade.

It has been proposed that modification of leaf size, driven by epidermal cell size, balances leaf water supply (determined by veins) with transpirational demand (generated by stomata) during acclimation to local irradiance. We aimed to determine whether this is a general pattern among plant species with contrasting growth habits. We compared observed relationships between leaf minor vein density, stomatal density, epidermal cell size and leaf size in four pairs of herbs and woody species from the same families grown under sun and shade conditions with modelled relationships assuming vein and stomatal densities respond passively to epidermal cell expansion. Leaf lignin content was also quantified to assess whether construction costs of herbaceous leaf veins differ from those of woody plants and the leaf mass fraction invested in veins. Modelled relationships accurately described observed relationships, indicating that in all species, co-ordinated changes to the density of minor veins and stomata were mediated by a common relationship between epidermal cell size, vein density and stomatal density, with little or no impact from stomatal index. This co-ordination was independent of changes in leaf size and is likely to be an adaptive process driven by the significant proportion of biomass invested in veins (13·1 % of sun leaf dry weight and 21·7 % of shade leaf dry weight). Relative costs of venation increased in the shade, intensifying selective pressure towards economizing investment in vein density. Modulation of epidermal cell size appears to be a general mechanism among our experimental species to maintain a constant ratio between leaf anatomical traits that control leaf water fluxes independently of habit. We propose that this process may co-ordinate plasticity in hydraulic supply and demand in the majority of eudicot angiosperms.

Within-canopy variation in photosynthetic capacity, SLA and foliar N in temperate broad-leaved trees with contrasting shade tolerance

The relative shade tolerance of T. cordata , F. sylvatica , and C. betulus in mature stands is based on different species-specific carbon and nitrogen allocation patterns. The leaf morphology and photosynthetic capacity of trees are remarkably plastic in response to intra-canopy light gradients. While most studies examined seedlings, it is not well understood how plasticity differs in mature trees among species with contrasting shade tolerance. We studied light-saturated net photosynthesis (A max), maximum carboxylation rate (V cmax), electron transport capacity (J max) and leaf dark respiration (R d) along natural light gradients in the canopies of 26 adult trees of five broad-leaved tree species in a mixed temperate old-growth forest (Fraxinus excelsior, Acer pseudoplatanus, Carpinus betulus, Tilia cordata and Fagus sylvatica), representing a sequence from moderately light-demanding to highly shade-tolerant species. We searched for species differences in the dependence of photosynthetic capacity on relative irradiance (RI), specific leaf area (SLA) and nitrogen per leaf area (N a ). The three shade-tolerant species (C. betulus, T. cordata, F. sylvatica) differed from the two more light-demanding species by the formation of shade leaves with particularly high SLA but relatively low N a and consequently lower area-based A max, and a generally higher leaf morphological and functional plasticity across the canopy. Sun leaf morphology and physiology were more similar among the two groups. The three shade-tolerant species differed in their shade acclimation strategies which are primarily determined by the species’ plasticity in SLA. Under low light, T. cordata and F. sylvatica increased SLA, mass-based foliar N and leaf size, while C. betulus increased solely SLA exhibiting only low intra-crown plasticity in leaf morphology and N allocation patterns. This study with mature trees adds to our understanding of tree species differences in shade acclimation strategies under the natural conditions of a mixed old-growth forest.

Synergistic inhibition effects of bamboo leaf extract/major components and iodide ion on the corrosion of steel in H3PO4 solution

The synergistic inhibition effects of the bamboo of Dendrocalmus sinicus Chia et J.L. Sun leaf extract (DSCLE)/major compounds (rutin and orientin) and iodide ion (I−) on the corrosion of cold rolled steel (CRS) in 0.1M H3PO4 solution at 25–60°C was studied by weight loss, potentiodynamic polarization curves, electrochemical impedance spectroscopy (EIS) and quantum chemical calculation methods. DSCLE and two major compounds act as moderate inhibitors, and inhibition efficiency follows the order: DSCLE>rutin>orientin. However, incorporation of them with I− significantly improved the inhibition performance, and produced strong synergistic inhibition effect.

Morfo-anatomía de las hojas de Celtis ehrenbergiana (Celtidaceae) desarrolladas bajo condiciones naturales de sol y sombra

El objetivo del presente trabajo fue establecer las características de las hojas de Celtis ehrenbergiana (Klotzsch) Liebm. (Celtidaceae), desarrolladas bajo condiciones naturales de sol y de sombra. Se estudiaron hojas maduras tomadas de ramas ubicadas en la parte media de la copa del árboly entre la quinta y séptima hoja desde el ápice. Las hojas de sombra son herbáceas, con lámina delgada de color verde claro; la estructura es bifacial, la epidermis presenta células con paredes anticlinales ondulado-sinuosas, el mesófilo está formado por parénquima en empalizada adaxial y esponjoso abaxial y el colénquima es angular-lagunar. Las hojas de sol son coriáceas, con lámina gruesa de color verde oscuro; la estructura es equifacial, la epidermis presenta células con paredes anticlinales rectas, el mesófilo es homogéneo en empalizada y el colénquima angular-masivo. En las hojas de sombra en la cara adaxial, no hay estomas o éstos son escasos, mientras que en las hojas de sol son numerosos. La variación de los caracteres morfo-anatómicos de la hoja evidenció la plasticidad fenotípica de esta especie.

Forest habitat, not leaf phenotype, predicts late‐season folivory of Quercus alba saplings

Summary1. Natural sunlight gradients occur on multiple scales in space and time. However, the direct (via habitat) and indirect effects (via plant quality) of light environment are often confounded, obscuring the relative importance of each in influencing herbivore responses.2. Potted saplings of Quercus alba (white oak, Fagaceae) were grown in either full sun or full shade from budburst to leaf hardening to manipulate leaf phenotype (creating sun or shade leaves), then placed in either sunny light gaps or adjacent shaded forest understorey habitats. This two‐way factorial design isolated the effects of sunlight level during leaf expansion from light environment late in the growing season on leaf phenology, leaf traits associated with host plant quality for herbivores, herbivore density and folivory.3. Sunlight level during leaf expansion and hardening had strong and persistent effects on Q. alba leaf phenology and phenotype. Shade saplings had later budburst (c. 4 days), and fewer but larger leaves, resulting in greater total leaf area compared with sun leaf saplings. Shade leaves had higher water content, specific leaf area and nitrogen content, and lower toughness, carbon content, C/N ratios and concentrations of hydrolysable and condensed tannins than sun leaves.4. Despite the apparent higher quality of shade leaves, forest habitat better predicted damage by folivores than leaf type, suggesting that the direct effects of light environment predominate for herbivory. Potted saplings of both leaf types placed in the shaded understorey suffered almost two times more folivory, on average, than saplings in sunny light gaps, despite more than three times higher mid‐season herbivore density on sun leaf saplings relative to shade leaf saplings.5. Taken together, these results suggest that both leaf phenotype and forest habitat, two factors frequently confounded in nature, have significant but distinct effects on leaf quality and herbivory. These findings have implications for plant–herbivore interactions following disturbances such as treefalls, when shade leaves may be present in sunny habitats, and may help explain patterns of herbivory in understorey plants with early leaf flushing phenology relative to the canopy, when sun leaves are present in the shaded understorey.

Inhibition of the corrosion of steel in HCl, H2SO4 solutions by bamboo leaf extract

The inhibition effect of the bamboo of Dendrocalmus sinicus Chia et J.L. Sun leaf extract (DSCLE) on the corrosion of cold rolled steel (CRS) in 1.0–5.0M HCl, 0.5–5.0M H2SO4 solutions was studied by weight loss, potentiodynamic polarization curves, electrochemical impedance spectroscopy (EIS) and atomic force microscope (AFM) methods. The results show that DSCLE is a good inhibitor in 1.0M HCl and 0.5M H2SO4, and inhibition efficiency follows the order: HCl>H2SO4. The adsorption of DSCLE on CRS surface obeys Langmuir adsorption isotherm, and acts as a mixed-type inhibitor in both acids.

Analyses of leaves from open field-grown transgenic poplars overexpressing xyloglucanase

The transgenic expression of Aspergillus xyloglucanase cDNA (AaXEG2) with 35S promoter in the leaves of open field-grown poplars was studied. The level of xyloglucan in the transgenic poplars was decreased to 15–16% in the non-fertile soil (forest-field soil) and to 21–22% in the fertile soil (farming-field soil) compared with that of the wild-type poplars. The leaves exhibited a smaller surface area with more rounded teeth than those of the wild-type plants, similar to the sun leaf variety that was grown in the incubation room and subsequently greenhoused. The majority of total veins with water-conducting vascular bundles were shorter in the leaves of the transgenic poplars than those of the wild type. This decrease in vein length may result from a decrease in xyloglucan during leaf development, from which large numbers of proteins were markedly downregulated in the leaves of the transgenic plants via proteomic analysis. It seems likely that the leaves of the transgenic poplars came to relax the edges of their tooth rather than extend their veins as a result of the loosening of the xyloglucan cellulose networks in the leaves.

Leaf functional traits and functional diversity of multistoried agroforests in West Java, Indonesia

We examined leaf trait variations among mixed-planting woody perennial crops in traditional but partially commercialized agroforest in West Java, Indonesia. We hypothesized that the structure of multistoried agroforests consisting of many species was sustained by differential use of the light resource by species with different leaf traits, and that functional diversity would decline as species diversity decreased due to commercialization of traditional agroforests. We focused on morphological and chemical traits of the fully exposed sun leaves and basal-interior leaves of 22 common perennial crops. The species varied as widely in their sun leaf traits as in previous studies of tropical lowland rain forests and in worldwide datasets. From one-third to half of the species exhibited significant differences in specific leaf area and in the nitrogen concentration per unit leaf mass between sun leaves and basal-interior leaves, likely in response to differences in irradiance and leaf age. Species within a product-type group (e.g., timber bamboos) generally had similar leaf traits. The diversity of functional leaf traits was significantly positively linearly correlated with species diversity, with no asymptote for functional diversity even at high levels of species diversity; thus, species diversity in the agroforests appears to maintain high ecosystem functioning through differential use of the available light resource. This also means that changing from the traditional multipurpose production system based on perennial crops into a specialized single-purpose system may damage ecosystem functions such as carbon sequestration. Understanding the leaf trait spectrum provides insights into other cash crops or cultivars that can fill gaps within the trait space in the plant assemblage, thereby improving profits from the agroforest while maintaining ecosystem functioning.

Tree age-related effects on sun acclimated leaves in a chronosequence of beech (Fagus sylvatica) stands.

The assessment of the effect of tree age on leaves is usually limited by the difficulty of sampling sun leaves from tall ageing trees. In this study, we investigated tree age-related effects on sun leaves in a chronosequence of beech (Fagus sylvatica L.) stands. The effects of stand age on leaf mass to area ratio (LMA), chlorophyll (Chl), epidermal polyphenols (EPhen), nitrogen and carbon contents in sun leaves were investigated in 17 even-aged stands distributed into six age classes (14-175 years old). Chl and EPhen were assessed in vivo with SPAD and Dualex portable leaf-clips respectively. Leaves were sampled by shooting and sun leaves were identified based on criteria obtained from a vertical profile of the ratio abaxial vs adaxial EPhen across the canopy. Sun leaves were characterised by a high and similar adaxial and abaxial EPhen contents, high LMA value and low mass-based Chl content. These sun leaf characteristics, together with leaf nitrogen and carbon contents, were not significantly affected by stand age. Along the chronosequence, beech trees invested a stable fraction of leaf mass into nitrogen, carbon, Chl and EPhen with decreasing leaf size, i.e. dry mass and area.

The Mitragyna Species of Ghana

Abstract The morphology and detailed anatomy of the leaves, stipules and young stems of Mitragyna stipulosa (D.C.) O. Kuntze, and Mitragyna ciliata Aubr. et Pellegr. have been described. Although the histological feaures are almost identical, the leaf of Mitragyna stipulosa has a typical shade leaf structure and that of Mitragyna ciliata a typical sun leaf structure.