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Sample records for abaxial leaf surface

  1. Silica Deposition in Abaxial Epidermis before the Opening of Leaf Blades of Pleioblastus chino (Poaceae, Bambusoideae)

    PubMed Central

    MOTOMURA, H.; FUJII, T.; SUZUKI, M.

    2006-01-01

    • Background and Aims Silica deposition is one of the important characteristics of the family Poaceae. The distribution, deposition process and physiology of silica in this family have been extensively investigated. Bamboos among members of Poaceae have leaves with a fairly long life span, and the leaves continuously accumulate silica in their tissues throughout their life, not only during the course of leaf opening, but also after opening. It has been revealed that the silica deposition process in relation to ageing of the bamboo leaf after opening differed depending on the cell types comprising the tissues. However, silica deposition has never been examined during the development and maturation periods of bamboo leaves. Hence, to clarify the silica deposition process in a developmental stage of the bamboo leaf, distribution of silica was observed in the abaxial epidermis before the opening of the leaf blades of Pleioblastus chino. • Methods Abaxial epidermal tissues of leaves were examined using a scanning electron microscope equipped with an energy dispersive X-ray microanalyser. • Key Results Among seven cell types comprising the abaxial epidermis, three types of cells, guard cells, prickle hairs and silica cells, deposited silica conspicuously, and another four types, cork cells, long cells, micro hairs and subsidiary cells, deposited only a little silica. Among the former group of cell types, silica cells and guard cells deposited silica over their entire surfaces, while prickle hairs deposited silica only in the point-tips. Silica deposition was detected firstly in prickle hairs, and then in silica cells and guard cells. Only silica cells were assumed to deposit silica conspicuously before leaf opening but not conspicuously after opening. • Conclusions Cell types in leaf epidermis of bamboo are classified into three groups according to the silica deposition pattern. Silica deposition in silica cells may be positive as a part of the physiological

  2. Characterization of photosynthetic gas exchange in leaves under simulated adaxial and abaxial surfaces alternant irradiation.

    PubMed

    Zhang, Zi-Shan; Li, Yu-Ting; Gao, Hui-Yuan; Yang, Cheng; Meng, Qing-Wei

    2016-01-01

    Previous investigations on photosynthesis have been performed on leaves irradiated from the adaxial surface. However, leaves usually sway because of wind. This action results in the alternating exposure of both the adaxial and abaxial surfaces to bright sunlight. To simulate adaxial and abaxial surfaces alternant irradiation (ad-ab-alt irradiation), the adaxial or abaxial surface of leaves were exposed to light regimes that fluctuated between 100 and 1,000 μmol m(-2) s(-1). Compared with constant adaxial irradiation, simulated ad-ab-alt irradiation suppressed net photosynthetic rate (Pn) and transpiration (E) but not water use efficiency. These suppressions were aggravated by an increase in alternant frequency of the light intensity. When leaves were transferred from constant light to simulated ad-ab-alt irradiation, the maximum Pn and E during the high light period decreased, but the rate of photosynthetic induction during this period remained constant. The sensitivity of photosynthetic gas exchange to simulated ad-ab-alt irradiation was lower on abaxial surface than adaxial surface. Under simulated ad-ab-alt irradiation, higher Pn and E were measured on abaxial surface compared with adaxial surface. Therefore, bifacial leaves can fix more carbon than leaves with two "sun-leaf-like" surfaces under ad-ab-alt irradiation. Photosynthetic research should be conducted under dynamic conditions that better mimic nature. PMID:27377989

  3. Characterization of photosynthetic gas exchange in leaves under simulated adaxial and abaxial surfaces alternant irradiation

    PubMed Central

    Zhang, Zi-Shan; Li, Yu-Ting; Gao, Hui-Yuan; Yang, Cheng; Meng, Qing-Wei

    2016-01-01

    Previous investigations on photosynthesis have been performed on leaves irradiated from the adaxial surface. However, leaves usually sway because of wind. This action results in the alternating exposure of both the adaxial and abaxial surfaces to bright sunlight. To simulate adaxial and abaxial surfaces alternant irradiation (ad-ab-alt irradiation), the adaxial or abaxial surface of leaves were exposed to light regimes that fluctuated between 100 and 1,000 μmol m−2 s−1. Compared with constant adaxial irradiation, simulated ad-ab-alt irradiation suppressed net photosynthetic rate (Pn) and transpiration (E) but not water use efficiency. These suppressions were aggravated by an increase in alternant frequency of the light intensity. When leaves were transferred from constant light to simulated ad-ab-alt irradiation, the maximum Pn and E during the high light period decreased, but the rate of photosynthetic induction during this period remained constant. The sensitivity of photosynthetic gas exchange to simulated ad-ab-alt irradiation was lower on abaxial surface than adaxial surface. Under simulated ad-ab-alt irradiation, higher Pn and E were measured on abaxial surface compared with adaxial surface. Therefore, bifacial leaves can fix more carbon than leaves with two “sun-leaf-like” surfaces under ad-ab-alt irradiation. Photosynthetic research should be conducted under dynamic conditions that better mimic nature. PMID:27377989

  4. Semi-Rolled Leaf2 modulates rice leaf rolling by regulating abaxial side cell differentiation.

    PubMed

    Liu, Xiaofei; Li, Ming; Liu, Kai; Tang, Ding; Sun, Mingfa; Li, Yafei; Shen, Yi; Du, Guijie; Cheng, Zhukuan

    2016-04-01

    Moderate leaf rolling maintains the erectness of leaves and minimizes the shadowing between leaves which is helpful to establish ideal plant architecture. Here, we describe asrl2(semi-rolled leaf2) rice mutant, which has incurved leaves due to the presence of defective sclerenchymatous cells on the abaxial side of the leaf and displays narrow leaves and reduced plant height. Map-based cloning revealed that SRL2 encodes a novel plant-specific protein of unknown biochemical function.SRL2 was mainly expressed in the vascular bundles of leaf blades, leaf sheaths, and roots, especially in their sclerenchymatous cells. The transcriptional activities of several leaf development-related YABBY genes were significantly altered in the srl2 mutant. Double mutant analysis suggested that SRL2 and SHALLOT-LIKE1(SLL1)/ROLLED LEAF9(RL9) function in distinct pathways that regulate abaxial-side leaf development. Hence, SRL2 plays an important role in regulating leaf development, particularly during sclerenchymatous cell differentiation. PMID:26873975

  5. Semi-Rolled Leaf2 modulates rice leaf rolling by regulating abaxial side cell differentiation

    PubMed Central

    Liu, Xiaofei; Li, Ming; Liu, Kai; Tang, Ding; Sun, Mingfa; Li, Yafei; Shen, Yi; Du, Guijie; Cheng, Zhukuan

    2016-01-01

    Moderate leaf rolling maintains the erectness of leaves and minimizes the shadowing between leaves which is helpful to establish ideal plant architecture. Here, we describe a srl2 (semi-rolled leaf2) rice mutant, which has incurved leaves due to the presence of defective sclerenchymatous cells on the abaxial side of the leaf and displays narrow leaves and reduced plant height. Map-based cloning revealed that SRL2 encodes a novel plant-specific protein of unknown biochemical function. SRL2 was mainly expressed in the vascular bundles of leaf blades, leaf sheaths, and roots, especially in their sclerenchymatous cells. The transcriptional activities of several leaf development-related YABBY genes were significantly altered in the srl2 mutant. Double mutant analysis suggested that SRL2 and SHALLOT-LIKE1 (SLL1)/ROLLED LEAF9 (RL9) function in distinct pathways that regulate abaxial-side leaf development. Hence, SRL2 plays an important role in regulating leaf development, particularly during sclerenchymatous cell differentiation. PMID:26873975

  6. SHALLOT-LIKE1 is a KANADI transcription factor that modulates rice leaf rolling by regulating leaf abaxial cell development.

    PubMed

    Zhang, Guang-Heng; Xu, Qian; Zhu, Xu-Dong; Qian, Qian; Xue, Hong-Wei

    2009-03-01

    As an important agronomic trait, rice (Oryza sativa L.) leaf rolling has attracted much attention from plant biologists and breeders. Moderate leaf rolling increases the photosynthesis of cultivars and hence raises grain yield. However, the relevant molecular mechanism remains unclear. Here, we show the isolation and functional characterization of SHALLOT-LIKE1 (SLL1), a key gene controlling rice leaf rolling. sll1 mutant plants have extremely incurved leaves due to the defective development of sclerenchymatous cells on the abaxial side. Defective development can be functionally rescued by expression of SLL1. SLL1 is transcribed in various tissues and accumulates in the abaxial epidermis throughout leaf development. SLL1 encodes a SHAQKYF class MYB family transcription factor belonging to the KANADI family. SLL1 deficiency leads to defective programmed cell death of abaxial mesophyll cells and suppresses the development of abaxial features. By contrast, enhanced SLL1 expression stimulates phloem development on the abaxial side and suppresses bulliform cell and sclerenchyma development on the adaxial side. Additionally, SLL1 deficiency results in increased chlorophyll and photosynthesis. Our findings identify the role of SLL1 in the modulation of leaf abaxial cell development and in sustaining abaxial characteristics during leaf development. These results should facilitate attempts to use molecular breeding to increase the photosynthetic capacity of rice, as well as other crops, by modulating leaf development and rolling. PMID:19304938

  7. Comparing vegetation indices for remote chlorophyll measurement of white poplar and Chinese elm leaves with different adaxial and abaxial surfaces

    PubMed Central

    Lu, Shan; Lu, Xingtong; Zhao, Wenli; Liu, Yu; Wang, Zheyi; Omasa, Kenji

    2015-01-01

    Quick non-destructive assessment of leaf chlorophyll content (LCC) is important for studying phenotypes related to plant growth and stress resistance. This study was undertaken to investigate the quantitative relationship between LCC and different vegetation indices (VIs) on both adaxial and abaxial surfaces of white poplar (Populus alba), which has dense tubular hairs on its abaxial surface, and Chinese elm (Ulmus pumila var. pendula), which does not show obvious superficial differences except for lighter colour on the abaxial surface. Some published and newly developed VIs were tested to relate them to LCC. The results showed that most of the published VIs had strong relationships with LCC on the one-surface dataset, but did not show a clear relationship with LCC when both adaxial and abaxial surface reflectance data were included. Among the reflectance indices tested, the modified Datt index, (R 719−R 726)/(R 719−R 743), performed best and is proposed as a new index for remote estimation of chlorophyll content in plants with varying leaf surface structures. It explained 92% of LCC variation in this research, and the root mean square error of the LCC prediction was 5.23 μg/cm2. This new index is insensitive to the effects of adaxial and abaxial leaf surface structures and is strongly related to the variation in reflectance caused by chlorophyll content. PMID:26034132

  8. Loss of Abaxial Leaf Epicuticular Wax in Medicago truncatula irg1/palm1 Mutants Results in Reduced Spore Differentiation of Anthracnose and Nonhost Rust Pathogens[W

    PubMed Central

    Uppalapati, Srinivasa Rao; Ishiga, Yasuhiro; Doraiswamy, Vanthana; Bedair, Mohamed; Mittal, Shipra; Chen, Jianghua; Nakashima, Jin; Tang, Yuhong; Tadege, Million; Ratet, Pascal; Chen, Rujin; Schultheiss, Holger; Mysore, Kirankumar S.

    2012-01-01

    To identify genes that confer nonhost resistance to biotrophic fungal pathogens, we did a forward-genetics screen using Medicago truncatula Tnt1 retrotransposon insertion lines. From this screen, we identified an inhibitor of rust germ tube differentation1 (irg1) mutant that failed to promote preinfection structure differentiation of two rust pathogens, Phakopsora pachyrhizi and Puccinia emaculata, and one anthracnose pathogen, Colletotrichum trifolii, on the abaxial leaf surface. Cytological and chemical analyses revealed that the inhibition of rust preinfection structures in irg1 mutants is due to complete loss of the abaxial epicuticular wax crystals and reduced surface hydrophobicity. The composition of waxes on abaxial leaf surface of irg1 mutants had >90% reduction of C30 primary alcohols and a preferential increase of C29 and C31 alkanes compared with the wild type. IRG1 encodes a Cys(2)His(2) zinc finger transcription factor, PALM1, which also controls dissected leaf morphology in M. truncatula. Transcriptome analysis of irg1/palm1 mutants revealed downregulation of eceriferum4, an enzyme implicated in primary alcohol biosynthesis, and MYB96, a major transcription factor that regulates wax biosynthesis. Our results demonstrate that PALM1 plays a role in regulating epicuticular wax metabolism and transport and that epicuticular wax influences spore differentiation of host and nonhost fungal pathogens. PMID:22294617

  9. The ASYMMETRIC LEAVES Complex Employs Multiple Modes of Regulation to Affect Adaxial-Abaxial Patterning and Leaf Complexity[OPEN

    PubMed Central

    Husbands, Aman Y.; Benkovics, Anna H.; Nogueira, Fabio T.S.; Lodha, Mukesh; Timmermans, Marja C.P.

    2015-01-01

    Flattened leaf architecture is not a default state but depends on positional information to precisely coordinate patterns of cell division in the growing primordium. This information is provided, in part, by the boundary between the adaxial (top) and abaxial (bottom) domains of the leaf, which are specified via an intricate gene regulatory network whose precise circuitry remains poorly defined. Here, we examined the contribution of the ASYMMETRIC LEAVES (AS) pathway to adaxial-abaxial patterning in Arabidopsis thaliana and demonstrate that AS1-AS2 affects this process via multiple, distinct regulatory mechanisms. AS1-AS2 uses Polycomb-dependent and -independent mechanisms to directly repress the abaxial determinants MIR166A, YABBY5, and AUXIN RESPONSE FACTOR3 (ARF3), as well as a nonrepressive mechanism in the regulation of the adaxial determinant TAS3A. These regulatory interactions, together with data from prior studies, lead to a model in which the sequential polarization of determinants, including AS1-AS2, explains the establishment and maintenance of adaxial-abaxial leaf polarity. Moreover, our analyses show that the shared repression of ARF3 by the AS and trans-acting small interfering RNA (ta-siRNA) pathways intersects with additional AS1-AS2 targets to affect multiple nodes in leaf development, impacting polarity as well as leaf complexity. These data illustrate the surprisingly multifaceted contribution of AS1-AS2 to leaf development showing that, in conjunction with the ta-siRNA pathway, AS1-AS2 keeps the Arabidopsis leaf both flat and simple. PMID:26589551

  10. Genetic Variation and Divergence of Genes Involved in Leaf Adaxial-Abaxial Polarity Establishment in Brassica rapa.

    PubMed

    Liang, Jianli; Liu, Bo; Wu, Jian; Cheng, Feng; Wang, Xiaowu

    2016-01-01

    Alterations in leaf adaxial-abaxial (ad-ab) polarity are one of the main factors that influence leaf curvature. In Chinese cabbage, leaf incurvature is an essential prerequisite to the formation of a leafy head. Identifying ad-ab patterning genes and investigating their genetic variation may facilitate elucidation of the mechanisms underlying leaf incurvature during head formation. Comparative genomic analysis of 45 leaf ad-ab patterning genes in Brassica rapa based on 26 homologs of Arabidopsis thaliana indicated that these genes underwent expansion and were retained after whole genome triplication (WGT). We also assessed the nucleotide diversity and selection footprints of these 45 genes in a collection of 94 Brassica rapa accessions that were composed of heading and non-heading morphotypes. Six of the 45 genes showed significant negative Tajima's D indices and nucleotide diversity reduction in heading accessions compared to those in non-heading accessions, indicating that they underwent purifying selection. Further testing of the BrARF3.1 gene, which was one of the selection signals from a larger collection, confirmed that purifying selection did occur. Our results provide genetic evidence that ad-ab patterning genes are involved in leaf incurvature, which is associated with formation of a leafy head, as well as promote an understanding of the genetic mechanism underlying leafy head formation in Chinese cabbage. PMID:26904064

  11. Genetic Variation and Divergence of Genes Involved in Leaf Adaxial-Abaxial Polarity Establishment in Brassica rapa

    PubMed Central

    Liang, Jianli; Liu, Bo; Wu, Jian; Cheng, Feng; Wang, Xiaowu

    2016-01-01

    Alterations in leaf adaxial-abaxial (ad-ab) polarity are one of the main factors that influence leaf curvature. In Chinese cabbage, leaf incurvature is an essential prerequisite to the formation of a leafy head. Identifying ad-ab patterning genes and investigating their genetic variation may facilitate elucidation of the mechanisms underlying leaf incurvature during head formation. Comparative genomic analysis of 45 leaf ad-ab patterning genes in Brassica rapa based on 26 homologs of Arabidopsis thaliana indicated that these genes underwent expansion and were retained after whole genome triplication (WGT). We also assessed the nucleotide diversity and selection footprints of these 45 genes in a collection of 94 Brassica rapa accessions that were composed of heading and non-heading morphotypes. Six of the 45 genes showed significant negative Tajima's D indices and nucleotide diversity reduction in heading accessions compared to those in non-heading accessions, indicating that they underwent purifying selection. Further testing of the BrARF3.1 gene, which was one of the selection signals from a larger collection, confirmed that purifying selection did occur. Our results provide genetic evidence that ad-ab patterning genes are involved in leaf incurvature, which is associated with formation of a leafy head, as well as promote an understanding of the genetic mechanism underlying leafy head formation in Chinese cabbage. PMID:26904064

  12. Ozone-induced ethylene release from leaf surfaces

    SciTech Connect

    Rodecap, K.D.; Tingey, D.T.

    1986-01-01

    Ozone-induced stress-ethylene emissions from the adaxial and abaxial leaf surfaces of four plant species (Glycine max (L) Merr. cv. Dare, Lycopersicon esculentum Mill cv. Roma VF, Eucalyptus globulus Labill. and Hedera helix L.) were studied to determine if the stress ethylene diffused through the stomata or cuticle. In plants not exposed to ozone, basal ethylene was detected above both the adaxial and abaxial leaf surfaces of all the plant species examined, indicating that some ethylene can diffuse across the leaf cuticle. Oxone-induced stress ethylene production in all species examined. These data indicate that ozone-induced stress ethylene primarily diffuses from the leaf via the stomata.

  13. Abaxial Greening Phenotype in Hybrid Aspen

    PubMed Central

    Nowak, Julia S.; Douglas, Carl J.; Cronk, Quentin C.B.

    2013-01-01

    The typical angiosperm leaf, as in Arabidopsis, is bifacial consisting of top (adaxial) and bottom (abaxial) surfaces readily distinguishable by the underlying cell type (palisade and spongy mesophyll, respectively). Species of the genus Populus have leaves that are either conventionally bifacial or isobilateral. Isobilateral leaves have palisade mesophyll on the top and bottom of the leaf, making the two sides virtually indistinguishable at the macroscopic level. In poplars this has been termed the “abaxial greening” phenotype. Previous work has implicated ASYMMETRIC LEAVES1 (AS1) as an essential determinant of palisade mesophyll development. This gene, as well as other genes (84 in all) putatively involved in setting the dorsiventral axis of leaves, were investigated in two Populus species: black cottonwood (Populus trichocarpa) and hybrid aspen (P. tremula x tremuloides), representative of each leaf type (bifacial and isobilateral, respectively). Poplar orthologs of AS1 have significantly higher expression in aspen leaf blade and lower in the petiole, suggestive of a potential role in the isobilateral leaf phenotype consistent with the previously observed phenotypes. Furthermore, an ABERRANT TESTA SHAPE (ATS) ortholog has significantly lower expression in aspen leaf tissue, also suggesting a possible contribution of this gene to abaxial greening. PMID:27137376

  14. Pattern Dynamics in Adaxial-Abaxial Specific Gene Expression Are Modulated by a Plastid Retrograde Signal during Arabidopsis thaliana Leaf Development

    PubMed Central

    Tameshige, Toshiaki; Fujita, Hironori; Watanabe, Keiro; Toyokura, Koichi; Kondo, Maki; Tatematsu, Kiyoshi; Matsumoto, Noritaka; Tsugeki, Ryuji; Kawaguchi, Masayoshi; Nishimura, Mikio; Okada, Kiyotaka

    2013-01-01

    The maintenance and reformation of gene expression domains are the basis for the morphogenic processes of multicellular systems. In a leaf primordium of Arabidopsis thaliana, the expression of FILAMENTOUS FLOWER (FIL) and the activity of the microRNA miR165/166 are specific to the abaxial side. This miR165/166 activity restricts the target gene expression to the adaxial side. The adaxial and abaxial specific gene expressions are crucial for the wide expansion of leaf lamina. The FIL-expression and the miR165/166-free domains are almost mutually exclusive, and they have been considered to be maintained during leaf development. However, we found here that the position of the boundary between the two domains gradually shifts from the adaxial side to the abaxial side. The cell lineage analysis revealed that this boundary shifting was associated with a sequential gene expression switch from the FIL-expressing (miR165/166 active) to the miR165/166-free (non-FIL-expressing) states. Our genetic analyses using the enlarged fil expression domain2 (enf2) mutant and chemical treatment experiments revealed that impairment in the plastid (chloroplast) gene expression machinery retards this boundary shifting and inhibits the lamina expansion. Furthermore, these developmental effects caused by the abnormal plastids were not observed in the genomes uncoupled1 (gun1) mutant background. This study characterizes the dynamic nature of the adaxial-abaxial specification process in leaf primordia and reveals that the dynamic process is affected by the GUN1-dependent retrograde signal in response to the failure of plastid gene expression. These findings advance our understanding on the molecular mechanism linking the plastid function to the leaf morphogenic processes. PMID:23935517

  15. OZONE-INDUCED ETHYLENE RELEASE FROM LEAF SURFACES

    EPA Science Inventory

    Ozone-induced stress ethylene emissions from the adaxial and abaxial leaf surfaces of four plant species (Glycine max (L) Merr. cv. Dare, Lycopersicon esculentum Mill cv. Roma VF, Eucalyptus globulus Labill. and Hedera helix L.) were studied to determine if the stress ethylene di...

  16. Optical effects of abaxial anthocyanin on absorption of red wavelengths by understorey species: revisiting the back-scatter hypothesis

    PubMed Central

    Hughes, Nicole M.; Vogelmann, Thomas C.; Smith, William K.

    2008-01-01

    A red/purple coloration of lower (abaxial) leaf surfaces is commonly observed in deeply-shaded understorey plants, especially in the tropics. However, the functional significance of red abaxial coloration, including its role in photosynthetic adaptation, remains unclear. The objective of this study was to test the back-scatter hypothesis for abaxial leaf coloration, which posits that red pigments internally reflect/scatter red light transmitted by the upper leaf surface back into the mesophyll, thereby enhancing photon capture in light-limited environments. Abaxially red/non-red variegated leaves of Begonia heracleifolia (Cham. & Schltdl.) were used to compare reflectance spectra and chlorophyll fluorescence profiles of abaxially anthocyanic (red) and acyanic (non-red) tissues under red light. Photosynthetic gas exchange in response to red light was also compared for abaxially red/non-red leaf sections. The results did not support a back-scattering function, as anthocyanic leaf surfaces were not more reflective of red light than acyanic surfaces. Anthocyanic tissues also did not exhibit any increases in the mesophyll absorbance of red light, or increased photosynthetic gas exchange under red light at any intensity, relative to acyanic tissues. These results suggest that abaxial anthocyanins do not significantly enhance the absorption of red light in the species tested, and alternative functions are discussed. PMID:18653695

  17. Distribution of the black pecan aphid on pecan leaf surfaces: an overview

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Three species of aphids (Hemiptera: Aphididae) regularly attack pecan, Carya illinoinensis, foliage. Two of these species, i.e., the blackmargined aphid, Monellia caryella and the yellow pecan aphid, Monelliopsis pecanis, are predominantly distributed on the abaxial leaf surface, as are adults and ...

  18. The Effects of Leaf Roughness, Surface Free Energy and Work of Adhesion on Leaf Water Drop Adhesion

    PubMed Central

    Wang, Huixia; Shi, Hui; Li, Yangyang; Wang, Yanhui

    2014-01-01

    The adhesion of water droplets to leaves is important in controlling rainfall interception, and affects a variety of hydrological processes. Leaf water drop adhesion (hereinafter, adhesion) depends not only on droplet formulation and parameters but also on the physical (leaf roughness) and physico-chemical (surface free energy, its components, and work-of-adhesion) properties of the leaf surface. We selected 60 plant species from Shaanxi Province, NW China, as experimental materials with the goal of gaining insight into leaf physical and physico-chemical properties in relation to the adhesion of water droplets on leaves. Adhesion covered a wide range of area, from 4.09 to 88.87 g/m2 on adaxial surfaces and 0.72 to 93.35 g/m2 on abaxial surfaces. Distinct patterns of adhesion were observed among species, between adaxial and abaxial surfaces, and between leaves with wax films and wax crystals. Adhesion decreased as leaf roughness increased (r =  −0.615, p = 0.000), but there were some outliers, such as Salix psammophila and Populus simonii with low roughness and low adhesion, and the abaxial surface of Hyoscyamus pusillus and the adaxial surface of Vitex negundo with high roughness and high adhesion. Meanwhile, adhesion was positively correlated with surface free energy (r = 0.535, p = 0.000), its dispersive component (r = 0.526, p = 0.000), and work of adhesion for water (r = 0.698, p = 0.000). However, a significant power correlation was observed between adhesion and the polar component of surface free energy (p = 0.000). These results indicated that leaf roughness, surface free energy, its components, and work-of-adhesion for water played important roles in hydrological characteristics, especially work-of-adhesion for water. PMID:25198355

  19. The effects of leaf roughness, surface free energy and work of adhesion on leaf water drop adhesion.

    PubMed

    Wang, Huixia; Shi, Hui; Li, Yangyang; Wang, Yanhui

    2014-01-01

    The adhesion of water droplets to leaves is important in controlling rainfall interception, and affects a variety of hydrological processes. Leaf water drop adhesion (hereinafter, adhesion) depends not only on droplet formulation and parameters but also on the physical (leaf roughness) and physico-chemical (surface free energy, its components, and work-of-adhesion) properties of the leaf surface. We selected 60 plant species from Shaanxi Province, NW China, as experimental materials with the goal of gaining insight into leaf physical and physico-chemical properties in relation to the adhesion of water droplets on leaves. Adhesion covered a wide range of area, from 4.09 to 88.87 g/m(2) on adaxial surfaces and 0.72 to 93.35 g/m(2) on abaxial surfaces. Distinct patterns of adhesion were observed among species, between adaxial and abaxial surfaces, and between leaves with wax films and wax crystals. Adhesion decreased as leaf roughness increased (r =  -0.615, p = 0.000), but there were some outliers, such as Salix psammophila and Populus simonii with low roughness and low adhesion, and the abaxial surface of Hyoscyamus pusillus and the adaxial surface of Vitex negundo with high roughness and high adhesion. Meanwhile, adhesion was positively correlated with surface free energy (r = 0.535, p = 0.000), its dispersive component (r = 0.526, p = 0.000), and work of adhesion for water (r = 0.698, p = 0.000). However, a significant power correlation was observed between adhesion and the polar component of surface free energy (p = 0.000). These results indicated that leaf roughness, surface free energy, its components, and work-of-adhesion for water played important roles in hydrological characteristics, especially work-of-adhesion for water. PMID:25198355

  20. Plastid control of abaxial-adaxial patterning

    PubMed Central

    Mateo-Bonmatí, Eduardo; Casanova-Sáez, Rubén; Quesada, Víctor; Hricová, Andrea; Candela, Héctor; Micol, José Luis

    2015-01-01

    Translational regulation, exerted by the cytosolic ribosome, has been shown to participate in the establishment of abaxial-adaxial polarity in Arabidopsis thaliana: many hypomorphic and null alleles of genes encoding proteins of the cytosolic ribosome enhance the leaf polarity defects of asymmetric leaves1 (as1) and as2 mutants. Here, we report the identification of the SCABRA1 (SCA1) nuclear gene, whose loss-of-function mutations also enhance the polarity defects of the as2 mutants. In striking contrast to other previously known enhancers of the phenotypes caused by the as1 and as2 mutations, we found that SCA1 encodes a plastid-type ribosomal protein that functions as a structural component of the 70S plastid ribosome and, therefore, its role in abaxial-adaxial patterning was not expected. PMID:26522839

  1. Evaporation Rate and Development of Wetted Area of Water Droplets with and without Surfactant at Different Locations on Waxy Leaf Surfaces

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The evaporation and formation of deposit patterns from single droplets deposited at various locations on waxy leaves were investigated under controlled conditions. Leaf locations included the interveinal area, midrib and secondary vein on both adaxial and abaxial surfaces. Tests were conducted with ...

  2. Wettability, Polarity, and Water Absorption of Holm Oak Leaves: Effect of Leaf Side and Age1[OPEN

    PubMed Central

    Fernández, Victoria; Sancho-Knapik, Domingo; Guzmán, Paula; Peguero-Pina, José Javier; Gil, Luis; Karabourniotis, George; Khayet, Mohamed; Fasseas, Costas; Heredia-Guerrero, José Alejandro; Heredia, Antonio; Gil-Pelegrín, Eustaquio

    2014-01-01

    Plant trichomes play important protective functions and may have a major influence on leaf surface wettability. With the aim of gaining insight into trichome structure, composition, and function in relation to water-plant surface interactions, we analyzed the adaxial and abaxial leaf surface of holm oak (Quercus ilex) as a model. By measuring the leaf water potential 24 h after the deposition of water drops onto abaxial and adaxial surfaces, evidence for water penetration through the upper leaf side was gained in young and mature leaves. The structure and chemical composition of the abaxial (always present) and adaxial (occurring only in young leaves) trichomes were analyzed by various microscopic and analytical procedures. The adaxial surfaces were wettable and had a high degree of water drop adhesion in contrast to the highly unwettable and water-repellent abaxial holm oak leaf sides. The surface free energy and solubility parameter decreased with leaf age, with higher values determined for the adaxial sides. All holm oak leaf trichomes were covered with a cuticle. The abaxial trichomes were composed of 8% soluble waxes, 49% cutin, and 43% polysaccharides. For the adaxial side, it is concluded that trichomes and the scars after trichome shedding contribute to water uptake, while the abaxial leaf side is highly hydrophobic due to its high degree of pubescence and different trichome structure, composition, and density. Results are interpreted in terms of water-plant surface interactions, plant surface physical chemistry, and plant ecophysiology. PMID:24913938

  3. 7 CFR 29.3036 - Leaf surface.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf surface. 29.3036 Section 29.3036 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Leaf surface. The smoothness or roughness of the web or lamina of a tobacco leaf. Leaf surface...

  4. 7 CFR 29.3036 - Leaf surface.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 2 2011-01-01 2011-01-01 false Leaf surface. 29.3036 Section 29.3036 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Leaf surface. The smoothness or roughness of the web or lamina of a tobacco leaf. Leaf surface...

  5. Geotaxis and leaf-surface preferences mitigate negative effects of a predatory mite on an herbivorous mite.

    PubMed

    Sudo, Masaaki; Osakabe, Masahiro

    2013-04-01

    Reproductive success and population growth of an herbivorous mite are limited by activities of phytoseiid predators. However, occurrences on upper versus lower leaf surfaces are sometimes mismatched between these prey and predators. The mismatch potentially mitigates predation risk for the prey species. We assessed factors that affect mite distributions on leaf surfaces, testing whether the presence of the phytoseiid mite Phytoseius nipponicus alters the leaf-surface distribution and reproductive success of the herbivorous false spider mite Brevipalpus obovatus. The host plant was Viburnum erosum var. punctatum (Adoxaceae). Leaves were set in natural (TRUE) and reversed (upside down; INVERTED) orientations using experimental devices. Both surfaces were accessible to mites. We detected lower and abaxial leaf-surface preferences in P. nipponicus. In contrast, upper and adaxial surfaces were preferred by B. obovatus. Thus, prey and predatory mites accumulated on different sides of leaves. Presence of the predator also indirectly decreased egg production in B. obovatus. Brevipalpus obovatus females actively avoided leaf surfaces with elevated predator numbers; these females shifted their distributions and changed oviposition sites to leaf surfaces with fewer predators. In consequence, B. obovatus eggs on the upper sides of leaves were less frequently preyed upon than were those on lower sides. We suggest that upper leaf-surface exploitation in this particular herbivorous mite species mitigates predation risk from phytoseiid mites, which prefer lower leaf surfaces. PMID:23011108

  6. Variations in the polarized leaf reflectance of Sorghum bicolor

    NASA Technical Reports Server (NTRS)

    Grant, Lois; Daughtry, C. S. T.; Vanderbilt, V. C.

    1987-01-01

    The polarized reflectance factor, Rq, of sorghum (Sorghum bicolor, L.) leaves from field-grown plants was measured in situ in the summers of 1983 and 1984. In 1983, three leaves of two randomly selected plants were measured at 2-week intervals. The value of Rq varied, depending on leaf and day of measurement. Measured values of Rq for the adaxial leaf surface ranged from 16 to 53; for the abaxial leaf surface the values ranged from 28 to 69. In 1984, measurements consisted of repeated observations made on the same leaf at biweekly intervals. The values of Rq from the adaxial leaf surface ranged from 26 to 38. Values of Rq from the abaxial leaf surface increased throughout the season, from 16 to 45. Differences in Rq were attributed to changes in surface details of the leaf.

  7. Stomatal penetration by aqueous solutions--an update involving leaf surface particles.

    PubMed

    Burkhardt, Juergen; Basi, Sabin; Pariyar, Shyam; Hunsche, Mauricio

    2012-11-01

    The recent visualization of stomatal nanoparticle uptake ended a 40-yr-old paradigm. Assuming clean, hydrophobic leaf surfaces, the paradigm considered stomatal liquid water transport to be impossible as a result of water surface tension. However, real leaves are not clean, and deposited aerosols may change hydrophobicity and water surface tension. Droplets containing NaCl, NaClO(3), (NH(4))(2) SO(4), glyphosate, an organosilicone surfactant or various combinations thereof were evaporated on stomatous abaxial and astomatous adaxial surfaces of apple (Malus domestica) leaves. The effects on photosynthesis, necrosis and biomass were determined. Observed using an environmental scanning electron microscope, NaCl and NaClO(3) crystals on hydrophobic tomato (Solanum lycopersicum) cuticles underwent several humidity cycles, causing repeated deliquescence and efflorescence of the salts. All physiological parameters were more strongly affected by abaxial than adaxial treatments. Spatial expansion and dendritic crystallization of the salts occurred and cuticular hydrophobicity was decreased more rapidly by NaClO(3) than NaCl. The results confirmed the stomatal uptake of aqueous solutions. Humidity fluctuations promote the spatial expansion of salts into the stomata. The ion-specific effects point to the Hofmeister series: chaotropic ions reduce surface tension, probably contributing to the defoliant action of NaClO(3), whereas the salt spray tolerance of coastal plants is probably linked to the kosmotropic nature of chloride ions. PMID:22985197

  8. Distinct Regulation of Adaxial-Abaxial Polarity in Anther Patterning in Rice[C][W][OA

    PubMed Central

    Toriba, Taiyo; Suzaki, Takuya; Yamaguchi, Takahiro; Ohmori, Yoshihiro; Tsukaya, Hirokazu

    2010-01-01

    Establishment of adaxial-abaxial polarity is essential for lateral organ development. The mechanisms underlying the polarity establishment in the stamen remain unclear, whereas those in the leaf are well understood. Here, we investigated a rod-like lemma (rol) mutant of rice (Oryza sativa), in which the development of the stamen and lemma is severely compromised. We found that the rod-like structure of the lemma and disturbed anther patterning resulted from defects in the regulation of adaxial-abaxial polarity. Gene isolation indicated that the rol phenotype was caused by a weak mutation in SHOOTLESS2 (SHL2), which encodes an RNA-dependent RNA polymerase and functions in trans-acting small interfering RNA (ta-siRNA) production. Thus, ta-siRNA likely plays an important role in regulating the adaxial-abaxial polarity of floral organs in rice. Furthermore, we found that the spatial expression patterns of marker genes for adaxial-abaxial polarity are rearranged during anther development in the wild type. After this rearrangement, a newly formed polarity is likely to be established in a new developmental unit, the theca primordium. This idea is supported by observations of abnormal stamen development in the shl2-rol mutant. By contrast, the stamen filament is likely formed by abaxialization. Thus, a unique regulatory mechanism may be involved in regulating adaxial-abaxial polarity in stamen development. PMID:20511295

  9. 7 CFR 29.3528 - Leaf surface.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... INSPECTION Standards Official Standard Grades for Dark Air-Cured Tobacco (u.s. Types 35, 36, 37 and Foreign Type 95) § 29.3528 Leaf surface. The roughness or smoothness of the web or lamina of a tobacco...

  10. 7 CFR 29.3528 - Leaf surface.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... INSPECTION Standards Official Standard Grades for Dark Air-Cured Tobacco (u.s. Types 35, 36, 37 and Foreign Type 95) § 29.3528 Leaf surface. The roughness or smoothness of the web or lamina of a tobacco...

  11. 7 CFR 29.3528 - Leaf surface.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... INSPECTION Standards Official Standard Grades for Dark Air-Cured Tobacco (u.s. Types 35, 36, 37 and Foreign Type 95) § 29.3528 Leaf surface. The roughness or smoothness of the web or lamina of a tobacco...

  12. 7 CFR 29.3528 - Leaf surface.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... INSPECTION Standards Official Standard Grades for Dark Air-Cured Tobacco (u.s. Types 35, 36, 37 and Foreign Type 95) § 29.3528 Leaf surface. The roughness or smoothness of the web or lamina of a tobacco...

  13. 7 CFR 29.3528 - Leaf surface.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... INSPECTION Standards Official Standard Grades for Dark Air-Cured Tobacco (u.s. Types 35, 36, 37 and Foreign Type 95) § 29.3528 Leaf surface. The roughness or smoothness of the web or lamina of a tobacco...

  14. Ecophysiological roles of abaxial anthocyanins in a perennial understorey herb from temperate deciduous forests

    PubMed Central

    Fernández-Marín, Beatriz; Esteban, Raquel; Míguez, Fátima; Artetxe, Unai; Castañeda, Verónica; Pintó-Marijuan, Marta; Becerril, José María; García-Plazaola, José Ignacio

    2015-01-01

    Accumulation of abaxial anthocyanins is an intriguing leaf trait particularly common among deeply shaded understorey plants of tropical and temperate forests whose ecological significance is still not properly understood. To shed light on it, possible ecophysiological roles of abaxial anthocyanins were tested in the perennial understorey herb of temperate deciduous forests Saxifraga hirsuta, chosen as a model species due to the coexistence of green and anthocyanic leaves and the presence of an easily removable lower anthocyanic epidermis. Anthocyanins accumulated during autumn, which temporally matched the overstorey leaf fall. Patterns of development of abaxial anthocyanins and direct measurements of photochemical efficiency under monochromatic light were not consistent with a photoprotective hypothesis. Enhancement of light capture also seemed unlikely since the back-scattering of red light towards the lower mesophyll was negligible. Seed germination was similar under acyanic and anthocyanic leaves. A relevant consequence of abaxial anthocyanins was the dramatic reduction of light transmission through the leaf. The dark environment generated underneath the Saxifraga canopy was enhanced by the horizontal repositioning of leaves, which occurs in parallel with reddening. This might play a role in biotic interactions by inhibiting vital processes of competitors, which may be of especial importance in spring before the overstorey leaves sprout. PMID:25922298

  15. An Apparent Anomaly in Peanut Leaf Conductance

    PubMed Central

    Pallas, James E.

    1980-01-01

    Conductance to gaseous transfer is normally considered to be greater from the abaxial than from the adaxial side of a leaf. Measurements of the conductance to water vapor of peanut leaves (Arachis hypogaea L.) under well watered and stress conditions in a controlled environment, however, indicated a 2-fold higher conductance from the adaxial side of the leaf than from the abaxial. Studies of conductance as light level was varied showed an increase in conductance from either surface with increasing light level, but conductance was always greater from the adaxial surface at any given light level. In contrast, measurements of soybean (Glycine max [L.] Merr.) and snapbean (Phaseolus vulgaris L.) leaf conductance showed an approximate 2-fold greater conductance from the abaxial surface than from the adaxial. Approximately the same number of stomata were present on both peanut leaf surfaces and stomatal size was similar. Electron microscopic examination of peanut leaves did not reveal any major structural differences between stomata on the two surfaces that would account for the differences in conductance. Light microscope studies of leaf sections revealed an extensive network of bundle sheaths with achloraplastic bundle sheath extensions; the lower epidermis was lined with a single layer of large achloraplastic parenchyma cells. Measurements of net photosynthesis made on upper and lower leaf surfaces collectively and individually indicated that two-thirds of the peanut leaf's total net photosynthesis can be attributed to diffusion of CO2 through the adaxial leaf surface. Possibly the high photosynthetic efficiency of peanut cultivars as compared with certain other C3 species is associated with the greater conductance of CO2 through their upper leaf surfaces. Images PMID:16661294

  16. Photosynthetic responses to leaf surface wetness in tropical plant species of Costa Rica with varying leaf traits

    NASA Astrophysics Data System (ADS)

    Aparecido, L. M. T.; Moore, G. W.; Miller, G. R.; Cahill, A. T.

    2015-12-01

    Wet tropical forests are some of the environments with the greatest annual precipitation, but are also considered as the world's major carbon sink; however, literature postulates that phothsynthesis rates are inhibited while leaves are wet. Yet measurements of photosynthesis during wet conditions are challenging to obtain due to equipment limitations and the extreme complexity of canopy-atmosphere interactions in tropical environments. The objective of this study was to evaluate tropical species reactions to simulated leaf wetness and test the hypothesis that leaf wetness reduces rates of photosynthesis. In a central Costa Rica site with an average 4200 mm annual rainfall, we selected six tropical species with distinct leaf traits in which five sun-exposed leaf replicates from each species were subjected to gas exchange measurements using a LI-6400 IRGA (LICOR Inc., Lincoln, NE) under dry and wet/misted leaf conditions. Relationships between photosynthesis (As) and stomatal conductance (gs) with leaf to air temperature difference (DT), VPD, and relative humidity were evaluated using linear regression analysis. We found that the responses varied greatly among species, but all plants maintained a baseline of activity under wet leaf conditions, suggesting that abaxial leaf As was a significant percentage of total leaf As. Stachytarpheta jamaicens had an 18.7% reduction in As, while others, like Zamia skinneri, had a 7% increase in As. Tibouchina heteromalla showed a rapid stomatal recovery of 2 mins, while Carapa guianensis was slower with 7 mins. This variability between species suggests that leaf traits, such as presence or absence of trichomes, water repellency, vein distribution and size and leaf angle variation, may be critical for optimizing photosynthesis under wet conditions. Relative humidity and leaf temperature were the strongest secondary influences on As and gs under wet leaf conditions. While tropical vegetation-atmosphere interactions are complex, such

  17. Polarized and specular reflectance variation with leaf surface features

    NASA Technical Reports Server (NTRS)

    Grant, Lois; Daughtry, C. S. T.; Vanderbilt, V. C.

    1993-01-01

    The linearly polarized reflectance from a leaf depends on the characteristics of the leaf surface. In the present study the leaf reflectance of a number of plant species with varying surface characteristics was measured at the Brewster angle with a polarization photometer having 5 visible and near-infrared wavelength bands. We found that all leaf surfaces polarized incident light. Differences among species could be explained by variation in surface features. The results support our hypothesis that the polarized light is reflected by the leaf surface, not by its interior. Two mechanisms appeared responsible for the linearly polarized reflectance: (1) specular reflectance and (2) surface particle scattering. In most cases, large values of linearly polarized reflectance could be attributed to specular reflectance from the leaf surface. Attribution required knowledge of the optical dimensions of features on the leaf surface.

  18. The rice bright green leaf (bgl) locus encodes OsRopGEF10, which activates the development of small cuticular papillae on leaf surfaces.

    PubMed

    Yoo, Jeong-Hoon; Park, Jong-Ho; Cho, Sung-Hwan; Yoo, Soo-Cheul; Li, Jinjie; Zhang, Haitao; Kim, Kwang-Soo; Koh, Hee-Jong; Paek, Nam-Chon

    2011-12-01

    Development of specialized epidermal cells and structures plays a key role in plant tolerance to biotic and abiotic stresses. In the paddy field, the bright green leaf (bgl) mutants of rice (Oryza sativa) exhibit a luminous green color that is clearly distinguishable from the normal green of wild-type plants. Transmission and scanning electron microscopy revealed that small cuticular papillae (or small papillae; SP), nipple-like structures, are absent on the adaxial and abaxial leaf surfaces of bgl mutants, leading to more direct reflection and less diffusion of green light. Map-based cloning revealed that the bgl locus encodes OsRopGEF10, one of eleven OsRopGEFs in rice. RopGEFs (guanine nucleotide exchange factors for Rop) activate Rop/Rac GTPases, acting as molecular switches in eukaryotic signal transduction by replacing the bound GDP (inactive form) with GTP (active form) in response to external or internal cues. In agreement with the timing of SP initiation on the leaf epidermis, OsRopGEF10 is most strongly expressed in newly developing leaves before emergence from the leaf sheath. In yeast two-hybrid assays, OsRopGEF10 interacts with OsRac1, one of seven OsRac proteins; consistent with this, both proteins are localized in the plasma membrane. These results suggest that OsRopGEF10 activates OsRac1 to turn on the molecular signaling pathway for SP development. Together, our findings provide new insights into the molecular genetic mechanism of SP formation during early leaf morphogenesis. PMID:22038138

  19. Simulating droplet motion on virtual leaf surfaces

    PubMed Central

    Mayo, Lisa C.; McCue, Scott W.; Moroney, Timothy J.; Forster, W. Alison; Kempthorne, Daryl M.; Belward, John A.; Turner, Ian W.

    2015-01-01

    A curvilinear thin film model is used to simulate the motion of droplets on a virtual leaf surface, with a view to better understand the retention of agricultural sprays on plants. The governing model, adapted from Roy et al. (2002 J. Fluid Mech. 454, 235–261 (doi:10.1017/S0022112001007133)) with the addition of a disjoining pressure term, describes the gravity- and curvature-driven flow of a small droplet on a complex substrate: a cotton leaf reconstructed from digitized scan data. Coalescence is the key mechanism behind spray coating of foliage, and our simulations demonstrate that various experimentally observed coalescence behaviours can be reproduced qualitatively. By varying the contact angle over the domain, we also demonstrate that the presence of a chemical defect can act as an obstacle to the droplet's path, causing break-up. In simulations on the virtual leaf, it is found that the movement of a typical spray size droplet is driven almost exclusively by substrate curvature gradients. It is not until droplet mass is sufficiently increased via coalescence that gravity becomes the dominating force. PMID:26064657

  20. Foraging on Individual Leaves by an Intracellular Feeding Insect Is Not Associated with Leaf Biomechanical Properties or Leaf Orientation

    PubMed Central

    Fiene, Justin; Kalns, Lauren; Nansen, Christian; Bernal, Julio; Harris, Marvin; Sword, Gregory A.

    2013-01-01

    Nearly all herbivorous arthropods make foraging-decisions on individual leaves, yet systematic investigations of the adaptive significance and ecological factors structuring these decisions are rare with most attention given to chewing herbivores. This study investigated why an intracellular feeding herbivore, Western flower thrips (WFT) Frankliniella occidentalis Pergande, generally avoids feeding on the adaxial leaf surface of cotton cotyledons. WFT showed a significant aversion to adaxial-feeding even when excised-cotyledons were turned up-side (abaxial-side ‘up’), suggesting that negative-phototaxis was not a primary cause of thrips foraging patterns. No-choice bioassays in which individual WFT females were confined to either the abaxial or adaxial leaf surface showed that 35% fewer offspring were produced when only adaxial feeding was allowed, which coincided with 32% less plant feeding on that surface. To test the hypothesis that leaf biomechanical properties inhibited thrips feeding on the adaxial surface, we used a penetrometer to measure two variables related to the ‘toughness’ of each leaf surface. Neither variable negatively co-varied with feeding. Thus, while avoiding the upper leaf surface was an adaptive foraging strategy, the proximate cause remains to be elucidated, but is likely due, in part, to certain leaf properties that inhibit feeding. PMID:24260510

  1. Leaf surfaces and the bioavailability of pesticide residues.

    PubMed

    Chowdhury, A B; Jepson, P C; Howse, P E; Ford, M G

    2001-05-01

    Laboratory bioassays were carried out to determine the toxicity to Folsomia candida Willem (Collembola: Isotomidae) of residues of a pyrethroid insecticide, deltamethrin, and an organophosphorus insecticide, dimethoate, on different leaf surfaces. The test leaves included a range of species and leaves of different ages. Dose-response relationships were estimated for F candida walking over the various treated leaf substrates. Probit analysis was used to estimate the means and standard deviations of the associated tolerance distributions expressed as gAIha-1. Parallelism tests were undertaken to compare the susceptibilities of F candida to the two compounds applied to the different leaf surfaces. On deltamethrin-treated leaf surfaces, the LD50 values for F candida varied from 6.36 to 77.14 gAIha-1. F candida was least susceptible to deltamethrin residues when applied to leaves of dwarf bean (Phaseolus vulgarus L) and the highest susceptibility was observed following application to leaves of seedlings of barley (Hordeum vulgare L). In contrast, the LD50 values observed for dimethoate treatments did not differ significantly between leaf types, ranging from 1.35 to 8.69 gAIha-1. The laboratory data on susceptibility of F candida on different leaf types for different pesticides can be used to investigate the role of leaf surface properties in modifying the toxicity of applied pesticides to exposed invertebrates. PMID:11374156

  2. Replication of Leaf Surface Structures for Light Harvesting

    PubMed Central

    Huang, Zhongjia; Yang, Sai; Zhang, Hui; Zhang, Meng; Cao, Wei

    2015-01-01

    As one of the most important hosts of natural light harvesting, foliage normally has complicated surface structures to capture solar radiances. Bio-mimicking leaf surface structures can provide novel designs of covers in photovoltaic systems. In this article, we reported on replicating leaf surface structures on poly-(methyl methacrylate) polymers to prompt harvesting efficiencies. Prepared via a double transfer process, the polymers were found to have high optical transparencies and transmission hazes, with both values exceeding 80% in some species. Benefiting from optical properties and wrinkled surfaces, the biomimetic polymers brought up to 17% gains to photovoltaic efficiencies. Through Monte-Carlo simulations of light transport, ultrahigh haze values and low reflections were attributed to lightwave guidance schemes lead by the nano- and micro-morphologies which are inherited from master leaves. Thus, leaf surface bio-mimicking can be considered as a strategic direction to design covers of light harvesting systems. PMID:26381702

  3. Replication of Leaf Surface Structures for Light Harvesting.

    PubMed

    Huang, Zhongjia; Yang, Sai; Zhang, Hui; Zhang, Meng; Cao, Wei

    2015-01-01

    As one of the most important hosts of natural light harvesting, foliage normally has complicated surface structures to capture solar radiances. Bio-mimicking leaf surface structures can provide novel designs of covers in photovoltaic systems. In this article, we reported on replicating leaf surface structures on poly-(methyl methacrylate) polymers to prompt harvesting efficiencies. Prepared via a double transfer process, the polymers were found to have high optical transparencies and transmission hazes, with both values exceeding 80% in some species. Benefiting from optical properties and wrinkled surfaces, the biomimetic polymers brought up to 17% gains to photovoltaic efficiencies. Through Monte-Carlo simulations of light transport, ultrahigh haze values and low reflections were attributed to lightwave guidance schemes lead by the nano- and micro-morphologies which are inherited from master leaves. Thus, leaf surface bio-mimicking can be considered as a strategic direction to design covers of light harvesting systems. PMID:26381702

  4. Crassulacean Acid Metabolism and Photochemical Efficiency of Photosystem II in the Adaxial and Abaxial Parts of the Succulent Leaves of Kalanchoë daigremontiana Grown at Four Photon Flux Densities.

    PubMed

    Winter, K; Awender, G

    1989-07-01

    Kalanchoë daigremontiana, a species possessing crassulacean acid metabolism, was grown at four photon flux densities (1300, 400, 60, and 25 micromole photons per square meter per second). In leaves which had developed at 1300 and 400 micromole photons per square meter per second, CO(2) was mainly incorporated through the lower, shaded leaf surfaces, and the chlorenchyma adjacent to the lower surfaces showed a higher degree of nocturnal acid synthesis than the chlorenchyma adjacent to the upper surfaces. In leaves acclimated to 60 and 25 micromole photons per square meter per second, the gradient in CAM activity was reversed, i.e. more CO(2) was taken up through the upper than through the lower surfaces and nocturnal acidification was higher in the tissue next to the upper surfaces. Total net carbon gain and total nocturnal acid synthesis were highest in leaves which had developed at 400 micromole photons per square meter per second. Chlorophyll content was markedly reduced in leaves which had developed at 1300 micromole photons per square meter per second, especially in the exposed adaxial parts. There was also a sustained reduction in photosystem II photochemical efficiency as indicated by measurements of the ratio of variable over maximum chlorophyll a fluorescence. These findings suggest that, at high growth photon flux densities, the reduced activity of the exposed portions of these succulent leaves is caused by (a) the adverse effects of excess light, (b) together with a genotypic component which favors CO(2) uptake and acid synthesis in the abaxial (lower) leaf parts even when light is not or only marginally excessive. This latter component is predominant at medium photon flux densities, e.g. at 400 micromole photons per square meter per second. It becomes overridden, however, under conditions of deep shade when strongly reduced light levels in the abaxial parts of the leaf chlorenchyma severely limit photosynthesis. PMID:16666903

  5. Pore size regulates operating stomatal conductance, while stomatal densities drive the partitioning of conductance between leaf sides

    PubMed Central

    Fanourakis, Dimitrios; Giday, Habtamu; Milla, Rubén; Pieruschka, Roland; Kjaer, Katrine H.; Bolger, Marie; Vasilevski, Aleksandar; Nunes-Nesi, Adriano; Fiorani, Fabio; Ottosen, Carl-Otto

    2015-01-01

    Background and Aims Leaf gas exchange is influenced by stomatal size, density, distribution between the leaf adaxial and abaxial sides, as well as by pore dimensions. This study aims to quantify which of these traits mainly underlie genetic differences in operating stomatal conductance (gs) and addresses possible links between anatomical traits and regulation of pore width. Methods Stomatal responsiveness to desiccation, gs-related anatomical traits of each leaf side and estimated gs (based on these traits) were determined for 54 introgression lines (ILs) generated by introgressing segments of Solanum pennelli into the S. lycopersicum ‘M82’. A quantitative trait locus (QTL) analysis for stomatal traits was also performed. Key Results A wide genetic variation in stomatal responsiveness to desiccation was observed, a large part of which was explained by stomatal length. Operating gs ranged over a factor of five between ILs. The pore area per stomatal area varied 8-fold among ILs (2–16 %), and was the main determinant of differences in operating gs between ILs. Operating gs was primarily positioned on the abaxial surface (60–83 %), due to higher abaxial stomatal density and, secondarily, to larger abaxial pore area. An analysis revealed 64 QTLs for stomatal traits in the ILs, most of which were in the direction of S. pennellii. Conclusions The data indicate that operating and maximum gs of non-stressed leaves maintained under stable conditions deviate considerably (by 45–91 %), because stomatal size inadequately reflects operating pore area (R2 = 0·46). Furthermore, it was found that variation between ILs in both stomatal sensitivity to desiccation and operating gs is associated with features of individual stoma. In contrast, genotypic variation in gs partitioning depends on the distribution of stomata between the leaf adaxial and abaxial epidermis. PMID:25538116

  6. Leaf physico-chemical and physiological properties of maize (Zea mays L.) populations from different origins.

    PubMed

    Revilla, Pedro; Fernández, Victoria; Álvarez-Iglesias, Lorena; Medina, Eva T; Cavero, José

    2016-10-01

    In this study we evaluated the leaf surface properties of maize populations native to different water availability environments. Leaf surface topography, wettability and gas exchange performance of five maize populations from the Sahara desert, dry (south) and humid (north-western) areas of Spain were analysed. Differences in wettability, stomatal and trichome densities, surface free energy and solubility parameter values were recorded between populations and leaf sides. Leaves from the humid Spanish population with special regard to the abaxial side, were less wettable and less susceptible to polar interactions. The higher wettability and hydrophilicity of Sahara populations with emphasis on the abaxial leaf surfaces, may favour dew deposition and foliar water absorption, hence improving water use efficiency under extremely dry conditions. Compared to the other Saharan populations, the dwarf one had a higher photosynthesis rate suggesting that dwarfism may be a strategy for improving plant tolerance to arid conditions. The results obtained for different maize populations suggest that leaf surfaces may vary in response to drought, but further studies will be required to examine the potential relationship between leaf surface properties and plant stress tolerance. PMID:27368072

  7. Effect of Surface-Active Pseudomonas spp. on Leaf Wettability

    PubMed Central

    Bunster, Lillian; Fokkema, Nyckle J.; Schippers, Bob

    1989-01-01

    Different strains of Pseudomonas putida and P. fluorescens isolated from the rhizosphere and phyllosphere were tested for surface activity in droplet cultures on polystyrene. Droplets of 6 of the 12 wild types tested spread over the surface during incubation, and these strains were considered surface active; strains not showing this reaction were considered non-surface active. Similar reactions were observed on pieces of wheat leaves. Supernatants from centrifuged broth cultures behaved like droplets of suspensions in broth; exposure to 100°C destroyed the activity. Average contact angles of the supernatants of surface-active and non-surface-active strains on polystyrene were 24° and 72°, respectively. The minimal surface tension of supernatants of the surface-active strains was about 46 mN/m, whereas that of the non-surface-active strains was 64 mN/m (estimations from Zisman plots). After 6 days of incubation, wheat flag leaves sprayed with a dilute suspension of a surface-active strain of P. putida (WCS 358RR) showed a significant increase in leaf wettability, which was determined by contact angle measurements. Increasing the initial concentration of bacteria and the amount of nutrients in the inoculum sprayed on leaves reduced the contact angles from 138° on leaves treated with antibiotics (control) to 43° on leaves treated with surface-active bacteria. A closely related strain with no surface activity on polystyrene did not affect leaf wettability, although it was present in densities similar to those of the surface-active strain. Nutrients alone could occasionally also increase leaf wettability, apparently by stimulating naturally occurring surface-active bacteria. When estimating densities of Pseudomonas spp. underneath droplets with low contact angles, it appeared that populations on leaves treated with a surface-active strain could vary from about 104 to 106 CFU cm−2, suggesting that the surface effect may be prolonged after a decline of the

  8. Surfactant Droplet Evaporation and Deposition Patterns on Waxy Leaf Surface

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Leaf surfaces are often altered when attacked by various insects and diseases. To evaluate the effect of droplet deposition on pesticide application efficiency, evaporation and deposit pattern formation of single droplets deposited at various locations on waxy leaves were investigated under controll...

  9. Comparative morphology of leaf epidermis in eight populations of Atlas Pistachio (Pistacia atlantica Desf., Anacardiaceae).

    PubMed

    Belhadj, Safia; Derridj, Arezki; Aigouy, Thierry; Gers, Charles; Gauquelin, Thierry; Mevy, Jean-Philippe

    2007-10-01

    A comparative analysis was undertaken to conduct a micromorphological study of Pistacia atlantica leaves by comparing different populations grown under different climatic conditions. Leaf epidermis of eight wild populations was investigated under scanning electron microscope. Micromorphological characteristics (epidermis ornament, stomata type, waxes as well as trichomes) of the adaxial and abaxial leaf surfaces were examined. The epidermis ornament varied among populations and leaf surface, the abaxial leaf surface is reticulate with a striate surface. Messaad site shows a smooth uneven surface. The adaxial leaf surface is smooth but several ornamentations can be seen. The leaflet is amphistomatic; the stomata appeared to be slightly sunken. A variety of stomatal types were recorded; actinocytic and anomocytic types are the most frequent. The indumentum consisted of glandular and nonglandular trichomes. Unicellular glandular trichomes are recorded for P. atlantica leaves in this study. Their density is higher in Oued safene site, located at the highest altitude in comparison with the other populations. The wax occurred in all the sites and its pattern varied according to the populations studied, particularly between Berriane and Messaad. The morphological variability exhibited by the eight populations of P. atlantica may be interpreted as relevant to the ecological plasticity and the physiological mechanisms involved are discussed in this report. PMID:17576128

  10. Trichomes as sensors: detecting activity on the leaf surface.

    PubMed

    Tooker, John F; Peiffer, Michelle; Luthe, Dawn S; Felton, Gary W

    2010-01-01

    The dramatic movements of some carnivorous plants species are triggered by sensory structures derived from trichomes. While unusual plant species such as the Venus fly trap and sundews may be expected to have elaborate sensors to capture their insect prey, more modest plant species might not be expected to have similar sensory capabilities. Our recent work, however, has revealed that glandular trichomes on tomato (Solanum lycopersicum) appear to have a function similar to trigger hairs of carnivorous species, acting as "early warning" sensors. Using a combination of behavioral, molecular, and biochemical techniques, we determined that caterpillars, moths and mechanical disruption upregulate signaling molecules and defensive genes found in glandular trichomes. Importantly, we discovered that plants whose trichomes have been broken respond more vigorously when their defenses were induced. Taken together, our results suggest that glandular trichomes can act as sensors that detect activity on the leaf surface, and ready plants for herbivore attack. PMID:20592816

  11. ASYMMETRIC LEAVES2 gene, a member of LOB/AS2 family of Arabidopsis thaliana, causes an abaxializing leaves in transgenic cockscomb.

    PubMed

    Sun, Shao-Bo; Song, Jiang-Ping; Meng, Lai-Sheng

    2012-04-01

    The leaf primordium derives from the peripheral zone of shoot apical meristem. During the formation of leaf primordia, they need to establish the proximodistal, mediolateral, and ab/adaxial axes. Among these axes, the ab/adaxial axis might be the most important. ASYMMETRIC LEAVES2 (AS2) gene is a member of AS2/LATERAL ORGAN BOUNDARY (LOB) family of Arabidopsis thaliana. In this work, we transformed 35S:AS2 transgene constructs to cockscomb (Celosia cristata) via Agrobacterium tumefaciens. All primary transformants subsequently obtained were placed into phenotypic categories and self-pollinated. As a whole, a total of 44 T1 35S:AS2 cockscomb plants obtained were grouped into two major categories: (I) slightly wrinkled leaves (28/44), (II) extremely curved leaves (16/44), on the basis of their leaf phenotypes. Furthermore, we characterized the anatomical features of these malformed leaves; and found the transformation of adaxial cell types into abaxial cell ones. A series of data suggest that AS2 might be involved in the determination of abaxial polarity in cockscomb plants. However, a few research teams have reported that AS2 might be involved in the determination of adaxial polarity in leaf primodia of Arabidopsis thaliana. These data above indicate that the roles of the same ab/adaxial determinant might differ between distinct species. At last, the different function of AS2 in distinct species was discussed. PMID:22143880

  12. What's So Bad about Being Wet All Over: Investigating Leaf Surface Wetness.

    ERIC Educational Resources Information Center

    Brewer, Carol A.

    1996-01-01

    Presents investigations of leaf surface wetness that provide ideal opportunities for students to explore the relationships between leaf form and function, to study surface conditions of leaves and plant physiology, and to make predictions about plant adaptation in different environments. Describes simple procedures for exploring questions related…

  13. Influence of Spray Formulation and Leaf Surface Structure on Droplet Evaporation and Wetted Area

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The fate of pesticide droplets on leaves is seriously influenced by spray formulations and fine structures on leaf surfaces. Evaporation times and wetted areas of droplets on hairy and waxy geranium leaf surfaces were determined under controlled conditions. Droplet evaporation processes were taken w...

  14. Leaf Area Influence on Surface Layer in a Deciduous Forest. Part 2; Detecting Leaf Area and Surface Resistance During Transition Seasons

    NASA Technical Reports Server (NTRS)

    Sakai, Ricardo K.; Fitzjarrald, David R.; Moore, Kathleen E.; Sicker, John W.; Munger, Willian J.; Goulden, Michael L.; Wofsy, Steven C.

    1996-01-01

    Temperate deciduous forest exhibit dramatic seasonal changes in surface exchange properties following on the seasonal changes in leaf area index. The canopy resistance to water vapor transport r(sub c) decreased abruptly at leaf emergence in each year but then also continued to decrease slowly during the remaining growing season due to slowly increasing LAI. Canopy resistance and PAR-albedo (albedo from photosynthetically active radiation) began to increase about one month before leaf fall with the diminishment of CO2 gradient above the canopy as well. At this time evaporation begun to be controlled as if the canopy were leafless.

  15. Flat leaf formation realized by cell-division control and mutual recessive gene regulation.

    PubMed

    Hayakawa, Yoshinori; Tachikawa, Masashi; Mochizuki, Atsushi

    2016-09-01

    Most of the land plants generally have dorsoventrally flat leaves, maximizing the surface area of both upper (adaxial) side and lower (abaxial) side. The former is specialized for light capturing for photosynthesis and the latter is specialized for gas exchange. From findings of molecular genetics, it has been considered that the coupled dynamics between tissue morphogenesis and gene regulation for cell identity is responsible for making flat leaves. The hypothesis claims that a flat leaf is generated under two assumptions, (i) two mutually recessive groups of genes specify adaxial and abaxial sides of a leaf, (ii) cell divisions are induced at the limited region in the leaf margin where both of two groups are expressed. We examined the plausibility and possibility of this hypothesis from the dynamical point of view. We studied a mathematical model where two processes are coupled, tissue morphogenesis induced by cell division and deformation, and dynamics of gene regulations. From the analysis of the model we found that the classically believed hypothesis is not sufficient to generate flat leaves with high probability. We examined several different modifications and revision of the model. Then we found that a simple additional rule of polarized cell division facilitates flat leaf formation. The result of our analysis gives prediction of possible mechanism, which can be easily verified in experiments. PMID:27287339

  16. Using the conservative nature of fresh leaf surface density to measure foliar area

    NASA Astrophysics Data System (ADS)

    Castillo, Omar S.; Zaragoza, Esther M.; Alvarado, Carlos J.; Barrera, Maria G.; Dasgupta-Schubert, Nabanita

    2014-10-01

    For a herbaceous species, the inverse of the fresh leaf surface density, the Hughes constant, is nearly conserved. We apply the Hughes constant to develop an absolute method of leafarea measurement that requires no regression fits, prior calibrations or oven-drying. The Hughes constant was determined in situ using a known geometry and weights of a sub-set obtained from the fresh leaves whose areas are desired. Subsequently, the leaf-areas (at any desired stratification level), were derived by utilizing the Hughes constant and the masses of the fresh leaves. The proof of concept was established for leaf-discs of the plants Mandevilla splendens and Spathiphyllum wallisii. The conservativeness of the Hughes constant over individual leaf-zones and different leaftypes from the leaves of each species was quantitatively validated. Using the globally averaged Hughes constant for each species, the leaf-area of these and additional co-species plants, were obtained. The leaf-area-measurement-by-mass was cross-checked with standard digital image analysis. There were no statistically significant differences between the leaf-area-measurement-by-mass and the digital image analysis measured leaf-areas and the linear correlation between the two methods was very good. Leaf-areameasurement- by-mass was found to be rapid and simple with accuracies comparable to the digital image analysis method. The greatly reduced cost of leaf-area-measurement-by-mass could be beneficial for small agri-businesses in developing countries.

  17. A System to investigate 3-D droplet impact on leaf surfaces

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A system was developed to investigate droplet dynamic impact and retention on leaf surfaces. The system consisted of a uniform droplet generator, two high speed digital video cameras, a constant speed track, a leaf holder, and a cool light source. The droplet generator produced mono-sized droplets r...

  18. INTERSPECFIC VARIATION IN SO2 FLUX - LEAF SURFACE 'VERSUS' INTERNAL FLUX, AND COMPONENTS OF LEAF CONDUCTANCE

    EPA Science Inventory

    The object of the study was to clarify the relationships among stomatal, residual, and epidermal conductances in determining the flux of SO2 air pollution to leaves. Variations in leaf SO2 and H2O vapor fluxes were determined using four plant species: Pisum sativum L. (garden pea...

  19. Effects of CO/sub 2/ enrichment on internal leaf surface area in soybeans

    SciTech Connect

    Leadley, P.W.; Reynolds, J.A.; Thomas, J.F.; Reynolds, J.F.

    1987-06-01

    Internal cell surface areas were measured on fully expanded leaves of soybean seedlings that had been continuously exposed to 348 or 645 ppm CO/sub 2/ environments. Plants grown in the high CO/sub 2/ treatment had thicker leaves but less palisade cell surface area per unit of leaf area. Surface area of the mesophyll per unit leaf area was unaffected by CO/sub 2/. The potential ramifications of these CO/sub 2/-induced changes in leaf anatomy on photosynthesis and water-use efficiency are explored.

  20. Genetic Framework for Flattened Leaf Blade Formation in Unifacial Leaves of Juncus prismatocarpus[C][W][OA

    PubMed Central

    Yamaguchi, Takahiro; Yano, Satoshi; Tsukaya, Hirokazu

    2010-01-01

    Angiosperm leaves generally develop as bifacial structures with distinct adaxial and abaxial identities. However, several monocot species, such as iris and leek, develop unifacial leaves, in which leaf blades have only abaxial identity. In bifacial leaves, adaxial-abaxial polarity is required for leaf blade flattening, whereas many unifacial leaves become flattened despite their leaf blades being abaxialized. Here, we investigate the mechanisms underlying the development and evolution of flattened leaf blades in unifacial leaves. We demonstrate that the unifacial leaf blade is abaxialized at the gene expression level and that an ortholog of the DROOPING LEAF (DL) gene may promote flattening of the unifacial leaf blade. In two closely related Juncus species, Juncus prismatocarpus, which has flattened unifacial leaves, and Juncus wallichianus, which has cylindrical unifacial leaves, DL expression levels and patterns correlate with the degree of laminar outgrowth. Genetic and expression studies using interspecific hybrids of the two species reveal that the DL locus from J. prismatocarpus flattens the unifacial leaf blade and expresses higher amounts of DL transcript than does that from J. wallichianus. We also show that leaf blade flattening is a trigger for central-marginal leaf polarity differentiation. We suggest that flattened unifacial leaf blades may have evolved via the recruitment of DL function, which plays a similar cellular but distinct phenotypic role in monocot bifacial leaves. PMID:20647346

  1. Measuring leaf material in ginned cotton from surface images

    NASA Astrophysics Data System (ADS)

    Taylor, Robert A.

    1995-01-01

    Digitized images from black and white video cameras are being used to measure the area and numbers of leaf particles in cotton after lint cleaning. The method is now used to provide trash grades for 16 - 18 million bales of cotton prepared for market each year. Small samples are compressed against a glass window and illuminated with two small incandescent lamps for imaging. Leaf area readings are automatically adjusted for differences in lint greyness. The accuracy of this method compares well with gravimetric measurements of non-lint content.

  2. Infection and decontamination of citrus-canker-inoculated leaf surfaces

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Citrus canker (Xanthomonas citri subsp. citri, Xcc) is now considered endemic in Florida and continues to spread. Personnel and equipment decontamination is practiced in both disease-endemic and disease-free areas to reduce the risk of bacterial spread by man or machinery. We used grapefruit leaf su...

  3. Bacterial leaf spot of radicchio (Cichorium intybus) is caused by Xanthomonas hortorum

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Beginning in 2002 a leaf spot disease of radicchio (Cichorium intybus) was observed in Monterey County, California. Lesions were maroon to dark brown in color; in some cases the margins of brown lesions became dark maroon with aging. Each leaf spot was observable from both adaxial and abaxial leaf s...

  4. Leaf micromorphology of some Phyllanthus L. species (Phyllanthaceae)

    NASA Astrophysics Data System (ADS)

    Solihani, N. S.; Noraini, T.; Azahana, A.; Nordahlia, A. S.

    2015-09-01

    Comparative leaf micromorphological study was conducted of five chosen Phyllanthus L. (Phyllanthaceae) species, namely P. acidus L., P. elegans Wall. ex Müll. Arg., P. emblica L., P. urinaria L. and P. pulcher Wall. ex Müll. Arg. The objective of this study is to identify the leaf micromorphological characteristics that can be used in species identification. The procedures involve examination under scanning electron microscope. Findings of this study have demonstrated variations in the leaf micromorphological characteristics such as in the types of waxes present on adaxial and abaxial epidermis surfaces, in the stomata and types of trichome. Common character present in all species studied are the presence of a thin film layer and buttress-like waxes on epidermal leaf surfaces. Diagnostics characters found in this study are the presence of papilla in P. elegens, amphistomatic stomata in P. urinaria and flaky waxes in P. pulcher. The result of this study has shown that leaf micromorphological characters have some taxonomic significance and can be used in identification of species in the genus Phyllanthus.

  5. Leaf micromorphology of some Phyllanthus L. species (Phyllanthaceae)

    SciTech Connect

    Solihani, N. S. Noraini, T.; Azahana, A.; Nordahlia, A. S.

    2015-09-25

    Comparative leaf micromorphological study was conducted of five chosen Phyllanthus L. (Phyllanthaceae) species, namely P. acidus L., P. elegans Wall. ex Müll. Arg., P. emblica L., P. urinaria L. and P. pulcher Wall. ex Müll. Arg. The objective of this study is to identify the leaf micromorphological characteristics that can be used in species identification. The procedures involve examination under scanning electron microscope. Findings of this study have demonstrated variations in the leaf micromorphological characteristics such as in the types of waxes present on adaxial and abaxial epidermis surfaces, in the stomata and types of trichome. Common character present in all species studied are the presence of a thin film layer and buttress-like waxes on epidermal leaf surfaces. Diagnostics characters found in this study are the presence of papilla in P. elegens, amphistomatic stomata in P. urinaria and flaky waxes in P. pulcher. The result of this study has shown that leaf micromorphological characters have some taxonomic significance and can be used in identification of species in the genus Phyllanthus.

  6. Leaf optical properties are affected by the location and type of deposited biominerals.

    PubMed

    Klančnik, Katja; Vogel-Mikuš, Katarina; Kelemen, Mitja; Vavpetič, Primož; Pelicon, Primož; Kump, Peter; Jezeršek, David; Gianoncelli, Alessandra; Gaberščik, Alenka

    2014-11-01

    This study aimed to relate the properties of incrusted plant tissues and structures as well as biomineral concentrations and localization with leaf reflectance and transmittance spectra from 280nm to 880nm in the grasses Phragmites australis, Phalaris arundinacea, Molinia caerulea and Deschampsia cespitosa, and the sedge Carex elata. Redundancy analysis revealed that prickle-hair length on adaxial surface and thickness of lower epidermis exerted significant effects in P. australis; prickle-hair density at abaxial leaf surface and thickness of epidermis on adaxial leaf surface in P. arundinacea; thickness of epidermis on adaxial leaf in D. cespitosa; prickle-hair density on adaxial leaf surface and thickness of cuticle in M. caerulea; and prickle-hair density on adaxial leaf surface and cuticle thickness of the lower side in C. elata. Micro-PIXE and LEXRF elemental localization analysis show that all of these structures and tissues are encrusted by Si and/or by Ca. Reflectance spectra were significantly affected by the Ca concentrations, while Si and Mg concentrations and the Ca concentrations significantly affected transmittance spectra. High concentrations of Mg were detected in epidermal vacuoles of P. arundinacea, M. caerulea and D. cespitosa. Al co-localises with Si in the cuticle, epidermis and/or prickle hairs. PMID:25194526

  7. MALDI-MS Imaging Analysis of Fungicide Residue Distributions on Wheat Leaf Surfaces.

    PubMed

    Annangudi, Suresh P; Myung, Kyung; Avila Adame, Cruz; Gilbert, Jeffrey R

    2015-05-01

    Improved retention and distribution of agrochemicals on plant surfaces is an important attribute in the biological activity of pesticide. Although retention of agrochemicals on plants after spray application can be quantified using traditional analytical techniques including LC or GC, the spatial distribution of agrochemicals on the plants surfaces has received little attention. Matrix assisted laser desorption/ionization (MALDI) imaging technology has been widely used to determine the distribution of proteins, peptides and metabolites in different tissue sections, but its application to environmental research has been limited. Herein, we probed the potential utility of MALDI imaging in characterizing the distribution of three commercial fungicides on wheat leaf surfaces. Using this MALDI imaging method, we were able to detect 500 ng of epoxiconazole, azoxystrobin, and pyraclostrobin applied in 1 μL drop on the leaf surfaces using MALDI-MS. Subsequent dilutions of pyraclostrobin revealed that the compound can be chemically imaged on the leaf surfaces at levels as low as 60 ng of total applied in the area of 1 μL droplet. After application of epoxiconazole, azoxystrobin, and pyraclostrobin at a field rate of 100 gai/ha in 200 L water using a track sprayer system, residues of these fungicides on the leaf surfaces were sufficiently visualized. These results suggest that MALDI imaging can be used to monitor spatial distribution of agrochemicals on leaf samples after pesticide application. PMID:25830667

  8. Establishing a framework for the Ad/abaxial regulatory network of Arabidopsis: ascertaining targets of class III homeodomain leucine zipper and KANADI regulation.

    PubMed

    Reinhart, Brenda J; Liu, Tie; Newell, Nicole R; Magnani, Enrico; Huang, Tengbo; Kerstetter, Randall; Michaels, Scott; Barton, M Kathryn

    2013-09-01

    The broadly conserved Class III homeodomain leucine zipper (HD-ZIPIII) and KANADI transcription factors have opposing and transformational effects on polarity and growth in all tissues and stages of the plant's life. To obtain a comprehensive understanding of how these factors work, we have identified transcripts that change in response to induced HD-ZIPIII or KANADI function. Additional criteria used to identify high-confidence targets among this set were presence of an adjacent HD-ZIPIII binding site, expression enriched within a subdomain of the shoot apical meristem, mutant phenotype showing defect in polar leaf and/or meristem development, physical interaction between target gene product and HD-ZIPIII protein, opposite regulation by HD-ZIPIII and KANADI, and evolutionary conservation of the regulator-target relationship. We find that HD-ZIPIII and KANADI regulate tissue-specific transcription factors involved in subsidiary developmental decisions, nearly all major hormone pathways, and new actors (such as indeterminate domain4) in the ad/abaxial regulatory network. Multiple feedback loops regulating HD-ZIPIII and KANADI are identified, as are mechanisms through which HD-ZIPIII and KANADI oppose each other. This work lays the foundation needed to understand the components, structure, and workings of the ad/abaxial regulatory network directing basic plant growth and development. PMID:24076978

  9. Establishing a Framework for the Ad/Abaxial Regulatory Network of Arabidopsis: Ascertaining Targets of Class III HOMEODOMAIN LEUCINE ZIPPER and KANADI Regulation[W

    PubMed Central

    Reinhart, Brenda J.; Liu, Tie; Newell, Nicole R.; Magnani, Enrico; Huang, Tengbo; Kerstetter, Randall; Michaels, Scott; Barton, M. Kathryn

    2013-01-01

    The broadly conserved Class III HOMEODOMAIN LEUCINE ZIPPER (HD-ZIPIII) and KANADI transcription factors have opposing and transformational effects on polarity and growth in all tissues and stages of the plant's life. To obtain a comprehensive understanding of how these factors work, we have identified transcripts that change in response to induced HD-ZIPIII or KANADI function. Additional criteria used to identify high-confidence targets among this set were presence of an adjacent HD-ZIPIII binding site, expression enriched within a subdomain of the shoot apical meristem, mutant phenotype showing defect in polar leaf and/or meristem development, physical interaction between target gene product and HD-ZIPIII protein, opposite regulation by HD-ZIPIII and KANADI, and evolutionary conservation of the regulator–target relationship. We find that HD-ZIPIII and KANADI regulate tissue-specific transcription factors involved in subsidiary developmental decisions, nearly all major hormone pathways, and new actors (such as INDETERMINATE DOMAIN4) in the ad/abaxial regulatory network. Multiple feedback loops regulating HD-ZIPIII and KANADI are identified, as are mechanisms through which HD-ZIPIII and KANADI oppose each other. This work lays the foundation needed to understand the components, structure, and workings of the ad/abaxial regulatory network directing basic plant growth and development. PMID:24076978

  10. Frequency, Size, and Localization of Bacterial Aggregates on Bean Leaf Surfaces

    PubMed Central

    Monier, J.-M.; Lindow, S. E.

    2004-01-01

    Using epifluorescence microscopy and image analysis, we have quantitatively described the frequency, size, and spatial distribution of bacterial aggregates on leaf surfaces of greenhouse-grown bean plants inoculated with the plant-pathogenic bacterium Pseudomonas syringae pv. syringae strain B728a. Bacterial cells were not randomly distributed on the leaf surface but occurred in a wide range of cluster sizes, ranging from single cells to over 104 cells per aggregate. The average cluster size increased through time, and aggregates were more numerous and larger when plants were maintained under conditions of high relative humidity levels than under dry conditions. The large majority of aggregates observed were small (less than 100 cells), and aggregate sizes exhibited a strong right-hand-skewed frequency distribution. While large aggregates are not frequent on a given leaf, they often accounted for the majority of cells present. We observed that up to 50% of cells present on a leaf were located in aggregates containing 103 cells or more. Aggregates were associated with several different anatomical features of the leaf surface but not with stomates. Aggregates were preferentially associated with glandular trichomes and veins. The biological and ecological significance of aggregate formation by epiphytic bacteria is discussed. PMID:14711662

  11. Linking the near-surface camera-based phenological metrics with leaf chemical and spectroscopic properties

    NASA Astrophysics Data System (ADS)

    Yang, X.; Tang, J.; Mustard, J. F.; Schmitt, J.

    2012-12-01

    Plant phenology is an important indicator of climate change. Near-surface cameras provide a way to continuously monitor plant canopy development at the scale of several hundred meters, which is rarely feasible by either traditional phenological monitoring methods or remote sensing. Thus, digital cameras are being deployed in national networks such as the National Ecological Observatory Network (NEON) and PhenoCam. However, it is unclear how the camera-based phenological metrics are linked with plant physiology as measured from leaf chemical and spectroscopic properties throughout the growing season. We used the temporal trajectories of leaf chemical properties (chlorophyll a and b, carotenoids, leaf water content, leaf carbon/nitrogen content) and leaf reflectance/transmittance (300 to 2500 nm) to understand the temporal changes of camera-based phenological metrics (e.g., relative greenness), which was acquired from our Standalone Phenological Observation System installed on a tower on the island of Martha's Vineyard, MA (dominant species: Quercus alba). Leaf chemical and spectroscopic properties of three oak trees near the tower were measured weekly from June to November, 2011. We found that the chlorophyll concentration showed similar temporal trajectories to the relative greenness. However, the change of chlorophyll concentration lagged behind the change of relative greenness for about 20 days both in the spring and the fall. The relative redness is a better indicator of leaf senescence in the fall than the relative greenness. We derived relative greenness from leaf spectroscopy and found that the relative greenness from camera matched well with that from the spectroscopy in the mid-summer, but this relationship faded as leaves start to fall, exposing the branches and soil background. This work suggests that we should be cautious to interpret camera-based phenological metrics, and the relative redness could potentially be a useful indicator of fall senescence.

  12. Characterization of dynamic droplet impaction and deposit formation on leaf surfaces

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Elucidation of droplet dynamic impaction and deposition formation on leaf surfaces would assist to optimize application strategies, improve biological control efficiency, and minimize pesticide waste. A custom-designed system consisting of two high-speed digital cameras and a uniform-size droplet ge...

  13. Phytotoxicity of Constituents of Glandular Trichomes and the Leaf Surface of Camphorweed, Heterotheca subaxillaris

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Camphorweed, Heterotheca subaxillaris (Lam.) Britt. & Rusby has a camphor-like odor, and its leaf surfaces contain glandular trichomes of the type shown to contain high levels of isoprenoids in other species. Phytotoxic calamenene-type sesquiterpenes (1-4, 8-10), borneol (11) and methylated flavone...

  14. Carbonized-leaf Membrane with Anisotropic Surfaces for Sodium-ion Battery.

    PubMed

    Li, Hongbian; Shen, Fei; Luo, Wei; Dai, Jiaqi; Han, Xiaogang; Chen, Yanan; Yao, Yonggang; Zhu, Hongli; Fu, Kun; Hitz, Emily; Hu, Liangbing

    2016-01-27

    A simple one-step thermal pyrolysis route has been developed to prepare carbon membrane from a natural leaf. The carbonized leaf membrane possesses anisotropic surfaces and internal hierarchical porosity, exhibiting a high specific capacity of 360 mAh/g and a high initial Coulombic efficiency of 74.8% as a binder-free, current-collector-free anode for rechargeable sodium ion batteries. Moreover, large-area carbon membranes with low contact resistance are fabricated by simply stacking and carbonizing leaves, a promising strategy toward large-scale sodium-ion battery developments. PMID:26727650

  15. The Heterogeneity and Spatial Patterning of Structure and Physiology across the Leaf Surface in Giant Leaves of Alocasia macrorrhiza

    PubMed Central

    Li, Shuai; Zhang, Yong-Jiang; Sack, Lawren; Scoffoni, Christine; Ishida, Atsushi; Chen, Ya-Jun; Cao, Kun-Fang

    2013-01-01

    Leaf physiology determines the carbon acquisition of the whole plant, but there can be considerable variation in physiology and carbon acquisition within individual leaves. Alocasia macrorrhiza (L.) Schott is an herbaceous species that can develop very large leaves of up to 1 m in length. However, little is known about the hydraulic and photosynthetic design of such giant leaves. Based on previous studies of smaller leaves, and on the greater surface area for trait variation in large leaves, we hypothesized that A. macrorrhiza leaves would exhibit significant heterogeneity in structure and function. We found evidence of reduced hydraulic supply and demand in the outer leaf regions; leaf mass per area, chlorophyll concentration, and guard cell length decreased, as did stomatal conductance, net photosynthetic rate and quantum efficiency of photosystem II. This heterogeneity in physiology was opposite to that expected from a thinner boundary layer at the leaf edge, which would have led to greater rates of gas exchange. Leaf temperature was 8.8°C higher in the outer than in the central region in the afternoon, consistent with reduced stomatal conductance and transpiration caused by a hydraulic limitation to the outer lamina. The reduced stomatal conductance in the outer regions would explain the observed homogeneous distribution of leaf water potential across the leaf surface. These findings indicate substantial heterogeneity in gas exchange across the leaf surface in large leaves, greater than that reported for smaller-leafed species, though the observed structural differences across the lamina were within the range reported for smaller-leafed species. Future work will determine whether the challenge of transporting water to the outer regions can limit leaf size for plants experiencing drought, and whether the heterogeneity of function across the leaf surface represents a particular disadvantage for large simple leaves that might explain their global rarity, even in

  16. ATP-binding cassette transporter controls leaf surface secretion of anticancer drug components in Catharanthus roseus

    PubMed Central

    Yu, Fang; De Luca, Vincenzo

    2013-01-01

    The Madagascar periwinkle (Catharanthus roseus) is highly specialized for the biosynthesis of many different monoterpenoid indole alkaloids (MIAs), many of which have powerful biological activities. Such MIAs include the commercially important chemotherapy drugs vinblastine, vincristine, and other synthetic derivatives that are derived from the coupling of catharanthine and vindoline. However, previous studies have shown that biosynthesis of these MIAs involves extensive movement of metabolites between specialized internal leaf cells and the leaf epidermis that require the involvement of unknown secretory processes for mobilizing catharanthine to the leaf surface and vindoline to internal leaf cells. Spatial separation of vindoline and catharanthine provides a clear explanation for the low levels of dimers that accumulate in intact plants. The present work describes the molecular cloning and functional identification of a unique catharanthine transporter (CrTPT2) that is expressed predominantly in the epidermis of young leaves. CrTPT2 gene expression is activated by treatment with catharanthine, and its in planta silencing redistributes catharanthine to increase the levels of catharanthine–vindoline drug dimers in the leaves. Phylogenetic analysis shows that CrTPT2 is closely related to a key transporter involved in cuticle assembly in plants and that may be unique to MIA-producing plant species, where it mediates secretion of alkaloids to the plant surface. PMID:24019465

  17. ATP-binding cassette transporter controls leaf surface secretion of anticancer drug components in Catharanthus roseus.

    PubMed

    Yu, Fang; De Luca, Vincenzo

    2013-09-24

    The Madagascar periwinkle (Catharanthus roseus) is highly specialized for the biosynthesis of many different monoterpenoid indole alkaloids (MIAs), many of which have powerful biological activities. Such MIAs include the commercially important chemotherapy drugs vinblastine, vincristine, and other synthetic derivatives that are derived from the coupling of catharanthine and vindoline. However, previous studies have shown that biosynthesis of these MIAs involves extensive movement of metabolites between specialized internal leaf cells and the leaf epidermis that require the involvement of unknown secretory processes for mobilizing catharanthine to the leaf surface and vindoline to internal leaf cells. Spatial separation of vindoline and catharanthine provides a clear explanation for the low levels of dimers that accumulate in intact plants. The present work describes the molecular cloning and functional identification of a unique catharanthine transporter (CrTPT2) that is expressed predominantly in the epidermis of young leaves. CrTPT2 gene expression is activated by treatment with catharanthine, and its in planta silencing redistributes catharanthine to increase the levels of catharanthine-vindoline drug dimers in the leaves. Phylogenetic analysis shows that CrTPT2 is closely related to a key transporter involved in cuticle assembly in plants and that may be unique to MIA-producing plant species, where it mediates secretion of alkaloids to the plant surface. PMID:24019465

  18. Fractal Surfaces of Molecular Crystals Mimicking Lotus Leaf with Phototunable Double Roughness Structures.

    PubMed

    Nishimura, Ryo; Hyodo, Kengo; Sawaguchi, Haruna; Yamamoto, Yoshiaki; Nonomura, Yoshimune; Mayama, Hiroyuki; Yokojima, Satoshi; Nakamura, Shinichiro; Uchida, Kingo

    2016-08-17

    Double roughness structure, the origin of the lotus effect of natural lotus leaf, was successfully reproduced on a diarylethene microcrystalline surface. Static superwater-repellency and dynamic water-drop-bouncing were observed on the surface, in the manner of natural lotus leaves. Double roughness structure was essential for water-drop-bouncing. This ability was not observed on a single roughness microcrystalline surface showing the lotus effect of the same diarylethene derivative. The double roughness structure was reversibly controlled by alternating irradiation with UV and visible light. PMID:27455376

  19. Auxin depletion from leaf primordia contributes to organ patterning

    PubMed Central

    Qi, Jiyan; Wang, Ying; Yu, Ting; Cunha, Alexandre; Wu, Binbin; Vernoux, Teva; Meyerowitz, Elliot; Jiao, Yuling

    2014-01-01

    Stem cells are responsible for organogenesis, but it is largely unknown whether and how information from stem cells acts to direct organ patterning after organ primordia are formed. It has long been proposed that the stem cells at the plant shoot apex produce a signal, which promotes leaf adaxial-abaxial (dorsoventral) patterning. Here we show the existence of a transient low auxin zone in the adaxial domain of early leaf primordia. We also demonstrate that this adaxial low auxin domain contributes to leaf adaxial-abaxial patterning. The auxin signal is mediated by the auxin-responsive transcription factor MONOPTEROS (MP), whose constitutive activation in the adaxial domain promotes abaxial cell fate. Furthermore, we show that auxin flow from emerging leaf primordia to the shoot apical meristem establishes the low auxin zone, and that this auxin flow contributes to leaf polarity. Our results provide an explanation for the hypothetical meristem-derived leaf polarity signal. Opposite to the original proposal, instead of a signal derived from the meristem, we show that a signaling molecule is departing from the primordium to the meristem to promote robustness in leaf patterning. PMID:25512543

  20. Auxin depletion from leaf primordia contributes to organ patterning.

    PubMed

    Qi, Jiyan; Wang, Ying; Yu, Ting; Cunha, Alexandre; Wu, Binbin; Vernoux, Teva; Meyerowitz, Elliot; Jiao, Yuling

    2014-12-30

    Stem cells are responsible for organogenesis, but it is largely unknown whether and how information from stem cells acts to direct organ patterning after organ primordia are formed. It has long been proposed that the stem cells at the plant shoot apex produce a signal, which promotes leaf adaxial-abaxial (dorsoventral) patterning. Here we show the existence of a transient low auxin zone in the adaxial domain of early leaf primordia. We also demonstrate that this adaxial low auxin domain contributes to leaf adaxial-abaxial patterning. The auxin signal is mediated by the auxin-responsive transcription factor MONOPTEROS (MP), whose constitutive activation in the adaxial domain promotes abaxial cell fate. Furthermore, we show that auxin flow from emerging leaf primordia to the shoot apical meristem establishes the low auxin zone, and that this auxin flow contributes to leaf polarity. Our results provide an explanation for the hypothetical meristem-derived leaf polarity signal. Opposite to the original proposal, instead of a signal derived from the meristem, we show that a signaling molecule is departing from the primordium to the meristem to promote robustness in leaf patterning. PMID:25512543

  1. Differential survival of solitary and aggregated bacterial cells promotes aggregate formation on leaf surfaces

    PubMed Central

    Monier, J.-M.; Lindow, S. E.

    2003-01-01

    The survival of individual Pseudomonas syringae cells was determined on bean leaf surfaces maintained under humid conditions or periodically exposed to desiccation stress. Cells of P. syringae strain B728a harboring a GFP marker gene were visualized by epifluorescence microscopy, either directly in situ or after recovery from leaves, and dead cells were identified as those that were stained with propidium iodide in such populations. Under moist, conducive conditions on plants, the proportion of total live cells was always high, irrespective of their aggregated state. In contrast, the proportion of the total cells that remained alive on leaves that were periodically exposed to desiccation stress decreased through time and was only ≈15% after 5 days. However, the fraction of cells in large aggregates that were alive on such plants in both condition was much higher than more solitary cells. Immediately after inoculation, cells were randomly distributed over the leaf surface and no aggregates were observed. However, a very aggregated pattern of colonization was apparent within 7 days, and >90% of the living cells were located in aggregates of 100 cells or more. Our results strongly suggest that, although conducive conditions favor aggregate formation, such cells are much more capable of tolerating environmental stresses, and the preferential survival of cells in aggregates promotes a highly clustered spatial distribution of bacteria on leaf surfaces. PMID:14665692

  2. TRANSPORT OF PHENOLIC COMPOUNDS FROM LEAF SURFACE OF CREOSOTEBUSH AND TARBUSH TO SOIL SURFACE BY PRECIPITATION

    Technology Transfer Automated Retrieval System (TEKTRAN)

    During the last 100 years, many desert grasslands have been replaced by shrublands. One possible mechanism by which shrubs outcompete grasses is through the release of compounds that interfere with neighboring plants. Our objective was to examine the movement of secondary compounds from the leaf s...

  3. The effect of axial and abaxial release on meniscal displacement in the dog.

    PubMed

    Kennedy, S C; Dunning, D; Bischoff, M G; Kuriashkin, I V; Pijanowski, G J; Schaeffer, D J

    2005-01-01

    The meniscal release (MR) is used to minimize meniscal pathology after Tibial Plateau Leveling Osteotomy (TPLO) surgery. The purposes of this study were: (i) to describe meniscal orientation in a unaltered cadaveric canine stifle, a cruciate deficient stifle, TPLO repaired stifle with and without the MR using magnetic resonance imaging; (ii) to determine if the abaxial release is equivalent to the axial release in its ability to affect caudal pole displacement in a TPLO repaired stifle and (iii) to evaluate with MRI the effect of MR on the femorotibiol articular cartilage contact area in a TPLO repaired stifle. Briefly, cadaver limbs were placed into a jig designed to mimic a weight-bearing stance at 140 degrees and 90 degrees at the stifle. The limbs were sequentially evaluated from the unaltered state; after cranial cruciate ligament transection; after TPLO stabilization; and finally after a meniscal release. No significant difference was found between the intrameniscal area (IMA) of the abaxial and axial meniscal releases although there was an increase in the IMA after the meniscal release compared to the IMA in the normal, cranial cruciate ligament deficient stifle, and TPLO stabilized stifle. In the abaxial release, a meniscal remnant remained in situ and provided a space effect between the femur and the tibial plateau. This is in contrast to the axial meniscal release, where the entire caudal pole of the medial meniscus relocated caudolaterally and consequently permitted more direct femorotibial contact. Overall, however, there was evidence of caudal pole compression of the medial meniscus throughout the MRI series which was ameliorated by either of the MR procedures. PMID:16594391

  4. Atomic force microscopy based nanoindentation study of onion abaxial epidermis walls in aqueous environment

    NASA Astrophysics Data System (ADS)

    Xi, Xiaoning; Kim, Seong H.; Tittmann, Bernhard

    2015-01-01

    An atomic force microscopy based nanoindentation method was employed to study how the structure of cellulose microfibril packing and matrix polymers affect elastic modulus of fully hydrated primary plant cell walls. The isolated, single-layered abaxial epidermis cell wall of an onion bulb was used as a test system since the cellulose microfibril packing in this cell wall is known to vary systematically from inside to outside scales and the most abundant matrix polymer, pectin, can easily be altered through simple chemical treatments such as ethylenediaminetetraacetic acid and calcium ions. Experimental results showed that the pectin network variation has significant impacts on the cell wall modulus, and not the cellulose microfibril packing.

  5. Atomic force microscopy based nanoindentation study of onion abaxial epidermis walls in aqueous environment

    SciTech Connect

    Xi, Xiaoning; Tittmann, Bernhard; Kim, Seong H.

    2015-01-14

    An atomic force microscopy based nanoindentation method was employed to study how the structure of cellulose microfibril packing and matrix polymers affect elastic modulus of fully hydrated primary plant cell walls. The isolated, single-layered abaxial epidermis cell wall of an onion bulb was used as a test system since the cellulose microfibril packing in this cell wall is known to vary systematically from inside to outside scales and the most abundant matrix polymer, pectin, can easily be altered through simple chemical treatments such as ethylenediaminetetraacetic acid and calcium ions. Experimental results showed that the pectin network variation has significant impacts on the cell wall modulus, and not the cellulose microfibril packing.

  6. Spatial scales of interactions among bacteria and between bacteria and the leaf surface.

    PubMed

    Esser, Daniel S; Leveau, Johan H J; Meyer, Katrin M; Wiegand, Kerstin

    2015-03-01

    Microbial life on plant leaves is characterized by a multitude of interactions between leaf colonizers and their environment. While the existence of many of these interactions has been confirmed, their spatial scale or reach often remained unknown. In this study, we applied spatial point pattern analysis to 244 distribution patterns of Pantoea agglomerans and Pseudomonas syringae on bean leaves. The results showed that bacterial colonizers of leaves interact with their environment at different spatial scales. Interactions among bacteria were often confined to small spatial scales up to 5-20 μm, compared to interactions between bacteria and leaf surface structures such as trichomes which could be observed in excess of 100 μm. Spatial point-pattern analyses prove a comprehensive tool to determine the different spatial scales of bacterial interactions on plant leaves and will help microbiologists to better understand the interplay between these interactions. PMID:25764562

  7. Spatial scales of interactions among bacteria and between bacteria and the leaf surface

    PubMed Central

    Esser, Daniel S.; Leveau, Johan H.J.; Meyer, Katrin M.; Wiegand, Kerstin

    2014-01-01

    Microbial life on plant leaves is characterized by a multitude of interactions between leaf colonizers and their environment. While the existence of many of these interactions has been confirmed, their spatial scale or reach often remained unknown. In this study, we applied spatial point pattern analysis to 244 distribution patterns of Pantoea agglomerans and Pseudomonas syringae on bean leaves. The results showed that bacterial colonizers of leaves interact with their environment at different spatial scales. Interactions among bacteria were often confined to small spatial scales up to 5–20 μm, compared to interactions between bacteria and leaf surface structures such as trichomes which could be observed in excess of 100 μm. Spatial point-pattern analyses prove a comprehensive tool to determine the different spatial scales of bacterial interactions on plant leaves and will help microbiologists to better understand the interplay between these interactions. PMID:25764562

  8. Leaf epidermal appendages of desert plant: an ecological perspective

    NASA Astrophysics Data System (ADS)

    Liu, Yubing; Li, Xinrong; Li, Mengmeng

    2014-05-01

    Desert plant often have few, tiny or no leaves, which reduces transpiration. The epidermis of their leaves is often ornamented outgrowths called trichomes or hairs and a thick waxy cuticle. Hairs on the leaf surface trap humidity in dry climates and waxy leaf surfaces reduce water loss. Our present study is to investigate the characteristics of trichomes and waxy cuticle in leaf surface of desert plant, which in the long term acclimation in semi-humid, semi-arid and arid ecosystems of Northern China, from east (Zhangwu county, Liaoning province) to west (Korla city, Xinjiang Uygur Autonomous Region), passing through several provinces including the Inner Mongolia Autonomous Region, Shanxi province, the Ningxia Hui Autonomous Region and Gansu province. 68 shrubs and 7 trees were selected in the natural habitats which were artificial sand fixing vegetation and the adjacent natural vegetation in sandy areas. The leaf epidermis was observed by scanning electron microscopy (SEM) and the cuticle thickness was calculated in the leaf cross-section by transmission electron microscopy (TEM). The results indicated that the epidermis of selected materials was divided into five categories: (1) Trichomes with different forms covered completely on the adaxial and abaxial surfaces of leaf, and any other epidermal appendages could not been observed. (2) Epicuticular wax crystals with different forms almost completely covered in the epistomatal chambers as well as on the surrounding epidermis, and there were no other appendages on the leaf surface. (3) A lot of warty hairs arranged neatly on the surface and the stomatal index was too low. (4) Several or even dozens of papillary epidermal cells covered with waxy crystals enclosed a sunken stomata chamber, therefore the stomatal density is very low. (5) Like ordinary terrestrial plants, epidermal cells and cell outline are clear, with epidermal hairs or not, and the stomata and waxy crystals are visible. TEM showed that desert plants

  9. Corynespora cassiicola leaf spot of pawpaw (Carica papaya L.) in Nigeria.

    PubMed

    Oluma, H O; Amuta, E U

    1999-01-01

    Leaf spot of pawpaw is hereby reported for the first time in Nigeria. The symptom is characterized by a papery center surrounded by a yellow halo. The causal organism is Corynespora cassiicola. Ripe fruits and abaxial surfaces of the leaves were significantly more susceptible to infection than unripe fruits and adaxial surfaces of leaves. Growth and sporulation of the fungus on several media was investigated. The organism grew faster on malt-extract agar (MEA) derived media and slowest on potato-dextrose agar (PDA) supplemented with thiamine. Sporulation was highest on Czapek-dox agar (CDA) plus biotin and lowest on PDA and PDA + thiamine. Reasons for increased susceptibility of ripe fruit are discussed. PMID:10560625

  10. Fluid drag reduction and efficient self-cleaning with rice leaf and butterfly wing bioinspired surfaces.

    PubMed

    Bixler, Gregory D; Bhushan, Bharat

    2013-09-01

    Researchers are continually inspired by living nature to solve complex challenges. For example, unique surface characteristics of rice leaves and butterfly wings combine the shark skin (anisotropic flow leading to low drag) and lotus leaf (superhydrophobic and self-cleaning) effects, producing the so-called rice and butterfly wing effect. In this paper, we present an overview of rice leaf and butterfly wing fluid drag and self-cleaning studies. In addition, we examine two other promising aquatic surfaces in nature known for such properties, including fish scales and shark skin. Morphology, drag, self-cleaning, contact angle, and contact angle hysteresis data are presented to understand the role of wettability, viscosity, and velocity. Liquid repellent coatings are utilized to recreate or combine various effects. Discussion is provided along with conceptual models describing the role of surface structures related to low drag, self-cleaning, and antifouling properties. Modeling provides design guidance when developing novel low drag and self-cleaning surfaces for applications in the medical, marine, and industrial fields. PMID:23884183

  11. Leaf surface chemicals fromNicotiana affecting germination ofPeronospora tabacina (adam) sporangia.

    PubMed

    Kennedy, B S; Nielsen, M T; Severson, R F; Sisson, V A; Stephenson, M K; Jackson, D M

    1992-09-01

    A bioassay was used to evaluate the effects of cuticular leaf components, isolated fromN. tabacum, N. glutinosa (accessions 24 and 24a), and 23other Nicotiana species, on germinationof P. tabacina (blue mold). The leaf surface compounds includedα- andβ-4,8,13,-duvatriene-l,3-diols (DVT-diols), (13-E)-labda-13-ene-8α-,15-diol (labdenediol), (12-Z)-labda-12,14-diene-8α-ol (cis-abienol), (13-R)-labda-8,14-diene-13-ol (manool), 2-hydroxymanool, a mixture of (13-R)-labda-14-ene-8α,13-diol (sclareol), and (13-S)-labda-14-ene-8α,13-diol (episclareol), and various glucose and/or sucrose ester isolates. The above in acetone were applied onto leaf disks of the blue moldsusceptibleN. tabacum cv. TI 1406, which was then inoculated with blue mold sporangia. Estimated IC50 values (inhibitory concentration) were 3.0μg/cm(2) forα-DVT-diol, 2.9μ/cm(2) forβ-DVT-diol, 0.4μg/cm(2) for labdenediol and 4.7μg/cm(2) for the sclareol mixture. Manool, 2-hydroxymanool, andcis-abienol at application rates up to 30μg/cm(2) had little or no effect on sporangium germination. Glucose and/or sucrose ester isolates from the cuticular leaf extracts of 23Nicotiana species and three different fractions fromN. bigelovii were also evaluated for antimicrobial activity at a concentration of 30μg/cm(2). Germination was inhibited by >20% when exposed to sugar esters isolated fromN. acuminata, N. benthamiana, N. attenuata, N. clevelandii, andN. miersii, and accessions 10 and 12 ofN. bigelovii. These results imply that a number of compounds may influence resistance to blue mold in tobacco. PMID:24254279

  12. Superhydrophobic, antiadhesive, and antireflective surfaces mediated by hybrid biomimetic salvinia leaf with moth-eye structures

    NASA Astrophysics Data System (ADS)

    Yang, Cho-Yun; Tsai, Yu-Lin; Yang, Cho-Yu; Sung, Cheng-Kuo; Yu, Peichen; Kuo, Hao-Chung

    2014-08-01

    In this paper, we successfully demonstrate multifunctional surfaces based on scaffolding biomimetic structures, namely, hybrid salvinia leaves with moth-eye structures (HSMSs). The novel fabrication process employs scalable polystyrene nanosphere lithography and a lift-off process. Systematic characterizations show the biomimetic HSMS exhibiting superhydrophobic, self-cleaning, antiadhesive, and antireflective properties. Furthermore, the resulting surface tension gradient (known as the Marangoni effect) leads to a superior air retention characteristic in the HSMS under water droplet impact, compared with the traditional hybrid lotus leaf with a moth-eye structure (HLMS). Such results and learnings pave the way towards the attainment and mass deployment of dielectric surfaces with multiple functionalities for versatile biological and optoelectronic applications.

  13. Methanol Emission from Leaves (Enzymatic Detection of Gas-Phase Methanol and Relation of Methanol Fluxes to Stomatal Conductance and Leaf Development).

    PubMed Central

    Nemecek-Marshall, M.; MacDonald, R. C.; Franzen, J. J.; Wojciechowski, C. L.; Fall, R.

    1995-01-01

    We recently reported the detection of methanol emissions from leaves (R. MacDonald, R. Fall [1993] Atmos Environ 27A: 1709-1713). This could represent a substantial flux of methanol to the atmosphere. Leaf methanol production and emission have not been investigated in detail, in part because of difficulties in sampling and analyzing methanol. In this study we used an enzymatic method to convert methanol to a fluorescent product and verified that leaves from several species emit methanol. Methanol was emitted almost exclusively from the abaxial surfaces of hypostomatous leaves but from both surfaces of amphistomatous leaves, suggesting that methanol exits leaves via stomates. The role of stomatal conductance was verified in experiments in which stomates were induced to close, resulting in reduced methanol. Free methanol was detected in bean leaf extracts, ranging from 26.8 [mu]g g-1 fresh weight in young leaves to 10.0 [mu]g g-1 fresh weight in older leaves. Methanol emission was related to leaf development, generally declining with increasing leaf age after leaf expansion; this is consistent with volatilization from a cellular pool that declines in older leaves. It is possible that leaf emission could be a major source of methanol found in the atmosphere of forests. PMID:12228547

  14. Leaf reflectance variation along a vertical crown gradient of two deciduous tree species in a Belgian industrial habitat.

    PubMed

    Khavaninzadeh, Ali Reza; Veroustraete, Frank; Van Wittenberghe, Shari; Verrelst, Jochem; Samson, Roeland

    2015-09-01

    The reflectometry of leaf asymmetry is a novel approach in the bio-monitoring of tree health in urban or industrial habitats. Leaf asymmetry responds to the degree of environmental pollution and reflects structural changes in a leaf due to environmental pollution. This paper describes the boundary conditions to scale up from leaf to canopy level reflectance, by describing the variability of adaxial and abaxial leaf reflectance, hence leaf asymmetry, along the crown height gradients of two tree species. Our findings open a research pathway towards bio-monitoring based on the airborne remote sensing of tree canopies and their leaf asymmetric properties. PMID:26057363

  15. Biomimetic and responsive artificial surfaces that quantitatively reproduce the water repellency of a Lotus leaf

    NASA Astrophysics Data System (ADS)

    Anastasiadis, Spiros H.; Zorba, Vassilia; Stratakis, Emmanuel; Barberoglou, Marios; Spanakis, Emmanuel; Tzanetakis, Panagiotis; Fotakis, Costas; Mateescu, Anca; Vamvakaki, Maria

    2009-03-01

    We report an efficient method for preparing superhydrophobic and highly water repellent surfaces by irradiating silicon wafers with femtosecond laser pulses and subsequently coating them with alkylsilanes or polymer brushes. Such surfaces exhibit controlled dual-scale roughness at the micro- and the nano-scale and water contact angle properties very similar to those of the Lotus leaf. The water repellency of the artificial surfaces is quantified by studying the restitution coefficient of water droplets bouncing off the surfaces as a function of the droplet impact velocity; this is the first time such a direct comparison of performance is made and it clearly demonstrates the possibility of designing highly efficient biomimetic water repellent surfaces. When a polymer brush is ``grafted from'' these surfaces based on a pH-sensitive polymer, these artificially structured surfaces can alter their behavior from super-hydrophilic (after immersion in a low pH buffer) to super-hydrophobic and water-repellent (following immersion to a high pH buffer). Sponsored by NATO's Scientific Affairs Division, by the Greek GSRT and by the EU.

  16. Bacterial succession on the leaf surface: a novel system for studying successional dynamics.

    PubMed

    Redford, Amanda J; Fierer, Noah

    2009-07-01

    Succession is a widely studied process in plant and animal systems, but succession in microbial communities has received relatively little attention despite the ubiquity of microorganisms in natural habitats. One important microbial habitat is the phyllosphere, or leaf surface, which harbors large, diverse populations of bacteria and offers unique opportunities for the study of succession and temporal community assembly patterns. To explore bacterial community successional patterns, we sampled phyllosphere communities on cottonwood (Populus deltoides) trees multiple times across the growing season, from leaf emergence to leaf fall. Bacterial community composition was highly variable throughout the growing season; leaves sampled as little as a week apart were found to harbor significantly different communities, and the temporal variability on a given tree exceeded the variability in community composition between individual trees sampled on a given day. The bacterial communities clearly clustered into early-, mid-, and late-season clusters, with early- and late-season communities being more similar to each other than to the mid-season communities, and these patterns appeared consistent from year to year. Although we observed clear and predictable changes in bacterial community composition during the course of the growing season, changes in phyllosphere bacterial diversity were less predictable. We examined the species-time relationship, a measure of species turnover rate, and found that the relationship was fundamentally similar to that observed in plant and invertebrate communities, just on a shorter time scale. The temporal dynamics we observed suggest that although phyllosphere bacterial communities have high levels of phylogenetic diversity and rapid turnover rates, these communities follow predictable successional patterns from season to season. PMID:19221834

  17. Spatial hydrologic heterogeneity within a fluvial catchment reflected in surface water and leaf wax n-alkane δD

    NASA Astrophysics Data System (ADS)

    Hoffmann, B.; Bookhagen, B.; Feakins, S. J.; Kahmen, A.; Olen, S. M.; Barthold, F. K.; Adhikari, D. P.; Sachse, D.

    2013-12-01

    During the past 10 years the hydrogen isotope composition of leaf wax n-alkanes from sedimentary archives has been established as a robust paleohydrological proxy. Leaf wax n-alkane δD values have been used to reconstruct paleohydrologic changes under the assumption that sedimentary archives represent an average of all synthesized leaf waxes within a catchment. However, especially for large river basins, little is known how catchment-wide heterogeneity in atmospheric and hydrologic processes is integrated into the formation, transportation, and deposition of leaf waxes. Specifically, the impact of transient fluvial transport processes on leaf wax accumulation remains unknown. In this study, we present data from the Arun river catchment in the eastern Nepalese Himalaya, which exhibits one of the steepest climatic gradients in the world with several meters of annual rainfall at the mountain front in the south and arid, cold conditions on the Tibetan Plateau in the north. As such, the Arun valley provides an excellent natural laboratory to investigate the δD value variability in both, modern meteoric water and sedimentary leaf wax n-alkanes, as well as drivers controlling the observed heterogeneities. To characterize the spatial distribution of rainfall δD values along the transect we sampled surface waters and used a Rayleigh modelling approach based on GNIP derived stable isotopic composition of meteoric water south of the Himalayan front and remotely sensed rainfall and evaporation rates. In addition we sampled leaf waxes from their sources (plants), during transport (cpom, >2mm) to their different natural archives (soils, river sediments) along the valley. We observed that sedimentary n-alkanes and water sampled south of the Himalayan front were characterized by most depleted δD values typical for glacial melt water from the higher Himalaya. Surface waters as well as leaf wax n-alkanes in the lower Himalayan tributaries were characterized by more enriched

  18. Optimization of olive leaf extract obtained by ultrasound-assisted extraction with response surface methodology.

    PubMed

    Şahin, Selin; Samlı, Rüya

    2013-01-01

    In the present article, ultrasound-assisted extraction (UAE) of polyphenols from agricultural and industrial waste of olive oil and table oil productions, olive tree (Olea europaea) leaves were investigated. The aim of the study is to examine the extraction parameters such as solvent concentration (0-100% ethanol (EtOH), v/v), the ratio of solid to solvent (25-50mg/mL) and extraction time (20-60 min), and to obtain the best possible combinations of these parameters through response surface methodology (RSM). The extract yield was stated as mg extract per g of dried leaf (DL). Total phenolic content was expressed in gallic acid equivalent (GAE) per g of dried leaf. Free radical scavenging activity for the antioxidant capacity was tested by 1,1-diphenyl-2-picryl hydrazyl (DPPH) radical. The second order polynomial model gave a satisfactory description of the experimental data. 201.2158 mg extract/g DL, 25.0626 mg GAE/g DL, and 95.5610% in respect to inhibition of DPPH radical were predicted at the optimum operating conditions (500 mg solid to 10 mL solvent ratio, 60 min of extraction time and 50% EtOH composition), respectively. PMID:22964032

  19. How does the VPD response of isohydric and anisohydric plants depend on leaf surface particles?

    PubMed

    Burkhardt, J; Pariyar, S

    2016-01-01

    Atmospheric vapour pressure deficit (VPD) is the driving force for plant transpiration. Plants have different strategies to respond to this 'atmospheric drought'. Deposited aerosols on leaf surfaces can interact with plant water relations and may influence VPD response. We studied transpiration and water use efficiency of pine, beech and sunflower by measuring sap flow, gas exchange and carbon isotopes, thereby addressing different time scales of plant/atmosphere interaction. Plants were grown (i) outdoors under rainfall exclusion (OD) and in ventilated greenhouses with (ii) ambient air (AA) or (iii) filtered air (FA), the latter containing <1% ambient aerosol concentrations. In addition, some AA plants were sprayed once with 25 mM salt solution of (NH4 )2 SO4 or NaNO3 . Carbon isotope values (δ(13) C) became more negative in the presence of more particles; more negative for AA compared to FA sunflower and more negative for OD Scots pine compared to other growth environments. FA beech had less negative δ(13) C than AA, OD and NaNO3 -treated beech. Anisohydric beech showed linearly increasing sap flow with increasing VPD. The slopes doubled for (NH4 )2 SO4 - and tripled for NaNO3 -sprayed beech compared to control seedlings, indicating decreased ability to resist atmospheric demand. In contrast, isohydric pine showed constant transpiration rates with increasing VPD, independent of growth environment and spray, likely caused by decreasing gs with increasing VPD. Generally, NaNO3 spray had stronger effects on water relations than (NH4 )2 SO4 spray. The results strongly support the role of leaf surface particles as an environmental factor affecting plant water use. Hygroscopic and chaotropic properties of leaf surface particles determine their ability to form wicks across stomata. Such wicks enhance unproductive water loss of anisohydric plant species and decrease CO2 uptake of isohydric plants. They become more relevant with increasing number of fine particles and

  20. Ecological distribution of leaf stomata and trichomes among tree species in a Malaysian lowland tropical rain forest.

    PubMed

    Ichie, Tomoaki; Inoue, Yuta; Takahashi, Narumi; Kamiya, Koichi; Kenzo, Tanaka

    2016-07-01

    The vertical structure of a tropical rain forest is complex and multilayered, with strong variation of micro-environment with height up to the canopy. We investigated the relation between morphological traits of leaf surfaces and tree ecological characteristics in a Malaysian tropical rain forest. The shapes and densities of stomata and trichomes on the abaxial leaf surfaces and their relation with leaf characteristics such as leaf area and leaf mass per area (LMA) were studied in 136 tree species in 35 families with different growth forms in the tropical moist forest. Leaf physiological properties were also measured in 50 canopy and emergent species. Most tree species had flat type (40.4 %) or mound type (39.7 %) stomata. In addition, 84 species (61.76 %) in 22 families had trichomes, including those with glandular (17.65 %) and non-glandular trichomes (44.11 %). Most leaf characteristics significantly varied among the growth form types: species in canopy and emergent layers and canopy gap conditions had higher stomatal density, stomatal pore index (SPI), trichome density and LMA than species in understory and subcanopy layers, though the relation of phylogenetically independent contrasts to each characteristic was not statistically significant, except for leaf stomatal density, SPI and LMA. Intrinsic water use efficiency in canopy and emergent tree species with higher trichome densities was greater than in species with lower trichome densities. These results suggest that tree species in tropical rain forests adapt to a spatial difference in their growth forms, which are considerably affected by phylogenetic context, by having different stomatal and trichome shapes and/or densities. PMID:26879931

  1. Seasonal variations in the chemical composition of vine-grape leaf surface.

    PubMed

    Batovska, D I; Todorova, I T; Bankova, V S; Parushev, S P; Atanassov, A I; Hvarleva, T D; Djakova, G J; Popov, S S

    2008-01-01

    Surface leaf metabolites of two seedlings of a Bulgarian winemaking cultivar Storgozia I(1) were analyzed in two seasons - summer (July) and autumn (October). The resistance towards some fungal pathogens of one of the plants was estimated as superior to the resistance of the other one. Significant seasonal variations in the chemical constituents of the two seedlings were observed. The main metabolites of the summer samples were sterols, terpenes, fatty acids and heterocyclic compounds. In autumn, sterol and fatty acid contents decreased, mono- and diterpenes and heterocyclic compounds disappeared and instead of them hydrocarbons and alcohols were detected. Some individual components - stearic acid, alpha-amyrin, lupeol and squalene - correlated with the estimated resistance and were therefore proposed as biomarkers for the fungal resistance in grape-vine leaves. PMID:18932086

  2. GC-MS analysis of the leaf surface components of four Bulgarian grapevines grown under different conditions.

    PubMed

    Batovska, D I; Todorova, I T; Djakova, G J; Ivanova, I I; Popov, S S

    2010-07-01

    Four grapevine seedlings were propagated and planted both in a greenhouse and in an experimental field. Surface components of their fresh leaves were easily obtained and analysed by gas chromatography-mass spectrometry. In total, 21 surface metabolites were identified. Unlike the greenhouse samples, the field ones possessed semiochemicals and compounds contributing to their survival under environmental stress. This study shows that the leaf surface of the grapevine possesses compounds indicating the conditions of breeding. PMID:20552525

  3. miR396-targeted AtGRF transcription factors are required for coordination of cell division and differentiation during leaf development in Arabidopsis

    PubMed Central

    Wang, Li; Gu, Xiaolu; Xu, Deyang; Wang, Wei; Wang, Hua; Zeng, Minhuan; Chang, Zhaoyang; Huang, Hai; Cui, Xiaofeng

    2011-01-01

    In plants, cell proliferation and polarized cell differentiation along the adaxial–abaxial axis in the primordium is critical for leaf morphogenesis, while the temporal–spatial relationships between these two processes remain largely unexplored. Here, it is reported that microRNA396 (miR396)-targeted Arabidopsis growth-regulating factors (AtGRFs) are required for leaf adaxial–abaxial polarity in Arabidopsis. Reduction of the expression of AtGRF genes by transgenic miR396 overexpression in leaf polarity mutants asymmetric leaves1 (as1) and as2 resulted in plants with enhanced leaf adaxial–abaxial defects, as a consequence of reduced cell proliferation. Moreover, transgenic miR396 overexpression markedly decreased the cell division activity and the expression of cell cycle-related genes, but resulted in an increased percentage of leaf cells with a higher ploidy level, indicating that miR396 negatively regulates cell proliferation by controlling entry into the mitotic cell cycle. miR396 is mainly expressed in the leaf cells arrested for cell division, coinciding with its roles in cell cycle regulation. These results together suggest that cell division activity mediated by miR396-targeted AtGRFs is important for polarized cell differentiation along the adaxial–abaxial axis during leaf morphogenesis in Arabidopsis. PMID:21036927

  4. Entrapment of bed bugs by leaf trichomes inspires microfabrication of biomimetic surfaces

    PubMed Central

    Szyndler, Megan W.; Haynes, Kenneth F.; Potter, Michael F.; Corn, Robert M.; Loudon, Catherine

    2013-01-01

    Resurgence in bed bug infestations and widespread pesticide resistance have greatly renewed interest in the development of more sustainable, environmentally friendly methods to manage bed bugs. Historically, in Eastern Europe, bed bugs were entrapped by leaves from bean plants, which were then destroyed; this purely physical entrapment was related to microscopic hooked hairs (trichomes) on the leaf surfaces. Using scanning electron microscopy and videography, we documented the capture mechanism: the physical impaling of bed bug feet (tarsi) by these trichomes. This is distinct from a Velcro-like mechanism of non-piercing entanglement, which only momentarily holds the bug without sustained capture. Struggling, trapped bed bugs are impaled by trichomes on several legs and are unable to free themselves. Only specific, mechanically vulnerable locations on the bug tarsi are pierced by the trichomes, which are located at effective heights and orientations for bed bug entrapment despite a lack of any evolutionary association. Using bean leaves as templates, we microfabricated surfaces indistinguishable in geometry from the real leaves, including the trichomes, using polymers with material properties similar to plant cell walls. These synthetic surfaces snag the bed bugs temporarily but do not hinder their locomotion as effectively as real leaves. PMID:23576783

  5. Theoretical Explanation of the Lotus Effect: Superhydrophobic Property Changes by Removal of Nanostructures from the Surface of a Lotus Leaf.

    PubMed

    Yamamoto, Minehide; Nishikawa, Naoki; Mayama, Hiroyuki; Nonomura, Yoshimune; Yokojima, Satoshi; Nakamura, Shinichiro; Uchida, Kingo

    2015-07-01

    Theoretical study is presented on the wetting behaviors of water droplets over a lotus leaf. Experimental results are interpreted to clarify the trade-offs among the potential energy change, the local pinning energy, and the adhesion energy. The theoretical parameters, calculated from the experimental results, are used to qualitatively explain the relations among surface fractal dimension, surface morphology, and dynamic wetting behaviors. The surface of a lotus leaf, which shows the superhydrophobic lotus effect, was dipped in ethanol to remove the plant waxes. As a result, the lotus effect is lost. The contact angle of a water drop decreased dramatically from 161° of the original surface to 122°. The water droplet was pinned on the surface. From the fractal analysis, the fractal region of the original surface was divided into two regions: a smaller-sized roughness region of 0.3-1.7 μm with D of 1.48 and a region of 1.7-19 μm with D of 1.36. By dipping the leaf in ethanol, the former fractal region, characterized by wax tubes, was lost, and only the latter large fractal region remained. The lotus effect is attributed to a surface structure that is covered with needle-shaped wax tubes, and the remaining surface allows invasion of the water droplet and enlarges the interaction with water. PMID:26075949

  6. The ULTRAPETALA1 trxG factor contributes to patterning the Arabidopsis adaxial-abaxial leaf polarity axis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The SAND domain protein ULTRAPETALA1 (ULT1) functions as a trithorax group factor that regulates a variety of developmental processes in Arabidopsis. We have recently shown that ULT1 regulates developmental patterning in the gynoecia and leaves. ULT1 acts together with the KANADI1 (KAN1) transcripti...

  7. Refinement of Eocene lapse rates, fossil-leaf altimetry, and North American Cordilleran surface elevation estimates

    NASA Astrophysics Data System (ADS)

    Feng, Ran; Poulsen, Christopher J.

    2016-02-01

    Estimates of continental paleoelevation using proxy methods are essential for understanding the geodynamic, climatic, and geomorphoric evolution of ancient orogens. Fossil-leaf paleoaltimetry, one of the few quantitative proxy approaches, uses fossil-leaf traits to quantify differences in temperature or moist enthalpy between coeval coastal and inland sites along latitudes. These environmental differences are converted to elevation differences using their rates of change with elevation (lapse rate). Here, we evaluate the uncertainty associated with this method using the Eocene North American Cordillera as a case study. To do so, we develop a series of paleoclimate simulations for the Early (∼55-49 Ma) and Middle Eocene (49-40 Ma) period using a range of elevation scenarios for the western North American Cordillera. Simulated Eocene lapse rates over western North America are ∼5 °C/km and 9.8 kJ/km, close to moist adiabatic rates but significantly different from modern rates. Further, using linear lapse rates underestimates high-altitude (>3 km) temperature variability and loss of moist enthalpy induced by non-linear circulation changes in response to increasing surface elevation. Ignoring these changes leads to kilometer-scale biases in elevation estimates. In addition to these biases, we demonstrate that previous elevation estimates of the western Cordillera are affected by local climate variability at coastal fossil-leaf sites of up to ∼8 °C in temperature and ∼20 kJ in moist enthalpy, a factor which further contributes to elevation overestimates of ∼1 km for Early Eocene floras located in the Laramide foreland basins and underestimates of ∼1 km for late Middle Eocene floras in the southern Cordillera. We suggest a new approach for estimating past elevations by comparing proxy reconstructions directly with simulated distributions of temperature and moist enthalpy under a range of elevation scenarios. Using this method, we estimate mean elevations for

  8. Spatial Organization of Dual-Species Bacterial Aggregates on Leaf Surfaces

    PubMed Central

    Monier, J.-M.; Lindow, S. E.

    2005-01-01

    The spatial organization of cells within bacterial aggregates on leaf surfaces was determined for pair-wise mixtures of three different bacterial species commonly found on leaves, Pseudomonas syringae, Pantoea agglomerans, and Pseudomonas fluorescens. Cells were coinoculated onto bean plants and allowed to grow under moist conditions, and the resulting aggregates were examined in situ by epifluorescence microscopy. Each bacterial strain could be localized because it expressed either the green or the cyan fluorescent protein constitutively, and the viability of individual cells was assessed by propidium iodide staining. Each pair of bacterial strains that was coinoculated onto leaves formed mixed aggregates. The degree of segregation of cells in mixed aggregates differed between the different coinoculated pairs of strains and was higher in mixtures of P. fluorescens A506 and P. agglomerans 299R and mixtures of P. syringae B728a and P. agglomerans 299R than in mixtures of two isogenic strains of P. agglomerans 299R. The fractions of the total cell population that were dead in mixed and monospecific aggregates of a gfp-marked strain of P. agglomerans 299R and a cfp-marked strain of P. agglomerans 299R, or of P. fluorescens A506 and P. agglomerans 299R, were similar. However, the proportion of dead cells in mixed aggregates of P. syringae B728a and P. agglomerans 299R was significantly higher (13.2% ± 8.2%) than that in monospecific aggregates of these two strains (1.6% ± 0.7%), and it increased over time. While dead cells in such mixed aggregates were preferentially found at the interface between clusters of cells of these strains, cells of these two strains located at the interface did not exhibit equal probabilities of mortality. After 9 days of incubation, about 77% of the P. agglomerans 299R cells located at the interface were dead, while only about 24% of the P. syringae B728a cells were dead. The relevance of our results to understanding bacterial interactions

  9. Influence of Seismic Stress on Photosynthetic Productivity, Gas Exchange, and Leaf Diffusive Resistance of Glycine max (L.) Merrill cv Wells II 1

    PubMed Central

    Pappas, Thalia; Mitchell, Cary A.

    1985-01-01

    Relative growth rate (RGR), leaf water potential (Ψw), transpiration rate (Tr), photosynthetic rate (Pn), and stomatal and mesophyll resistances to CO2 exchange were measured or calculated to determine how periodic seismic (shaking) stress decreased dry weight accumulation by soybean (Glycine max [L.] Merrill cv Wells II). Seismic stress was applied with a gyratory shaker at 240 to 280 revolutions per minute for 5 minutes three times daily at 0930, 1430, and 1930 hours. Fifteen days of treatment decreased stem length 21%, leaf area 17%, and plant dry weight 18% relative to undisturbed plants. Seismic stress also decreased RGR 4%, which was due entirely to decreased net assimilation rate. Transpiration decreased 17% and leaf Ψw increased 39% 30 minutes after treatment. A reduction in Pn began within seconds after the onset of treatment and had declined 16% after 20 minutes, at which time gradual recovery began. Assimilation rate recovered fully before the next seismic treatment 5 hours later. Resistance analysis and calculation of leaf internal CO2 levels indicated that the transitory decrease in Pn caused by periodic seismic stress was due to increased stomatal resistance on the abaxial leaf surface. Images Fig. 1 PMID:11540834

  10. The microbiome of the leaf surface of Arabidopsis protects against a fungal pathogen.

    PubMed

    Ritpitakphong, Unyarat; Falquet, Laurent; Vimoltust, Artit; Berger, Antoine; Métraux, Jean-Pierre; L'Haridon, Floriane

    2016-05-01

    We have explored the importance of the phyllosphere microbiome in plant resistance in the cuticle mutants bdg (BODYGUARD) or lacs2.3 (LONG CHAIN FATTY ACID SYNTHASE 2) that are strongly resistant to the fungal pathogen Botrytis cinerea. The study includes infection of plants under sterile conditions, 16S ribosomal DNA sequencing of the phyllosphere microbiome, and isolation and high coverage sequencing of bacteria from the phyllosphere. When inoculated under sterile conditions bdg became as susceptible as wild-type (WT) plants whereas lacs2.3 mutants retained the resistance. Adding washes of its phyllosphere microbiome could restore the resistance of bdg mutants, whereas the resistance of lacs2.3 results from endogenous mechanisms. The phyllosphere microbiome showed distinct populations in WT plants compared to cuticle mutants. One species identified as Pseudomonas sp isolated from the microbiome of bdg provided resistance to B. cinerea on Arabidopsis thaliana as well as on apple fruits. No direct activity was observed against B. cinerea and the action of the bacterium required the plant. Thus, microbes present on the plant surface contribute to the resistance to B. cinerea. These results open new perspectives on the function of the leaf microbiome in the protection of plants. PMID:26725246

  11. Response of Sunflower (Helianthus annuus L.) Leaf Surface Defenses to Exogenous Methyl Jasmonate

    PubMed Central

    Rowe, Heather C.; Ro, Dae-kyun; Rieseberg, Loren H.

    2012-01-01

    Helianthus annuus, the common sunflower, produces a complex array of secondary compounds that are secreted into glandular trichomes, specialized structures found on leaf surfaces and anther appendages of flowers. The primary components of these trichome secretions are sesquiterpene lactones (STL), a diverse class of compounds produced abundantly by the plant family Compositae and believed to contribute to plant defense against herbivory. We treated wild and cultivated H. annuus accessions with exogenous methyl jasmonate, a plant hormone that mediates plant defense against insect herbivores and certain classes of fungal pathogens. The wild sunflower produced a higher density of glandular trichomes on its leaves than the cultivar. Comparison of the profiles of glandular trichome extracts obtained by liquid chromatography–mass spectroscopy (LC-MS) showed that wild and cultivated H. annuus were qualitatively similar in surface chemistry, although differing in the relative size and proportion of various compounds detected. Despite observing consistent transcriptional responses to methyl jasmonate treatment, we detected no significant effect on glandular trichome density or LC-MS profile in cultivated or wild sunflower, with wild sunflower exhibiting a declining trend in overall STL production and foliar glandular trichome density of jasmonate-treated plants. These results suggest that glandular trichomes and associated compounds may act as constitutive defenses or require greater levels of stimulus for induction than the observed transcriptional responses to exogenous jasmonate. Reduced defense investment in domesticated lines is consistent with predicted tradeoffs caused by selection for increased yield; future research will focus on the development of genetic resources to explicitly test the ecological roles of glandular trichomes and associated effects on plant growth and fitness. PMID:22623991

  12. Fungitoxic effects of nonprotein imino acids on growth of saprophytic fungi isolated from the leaf surface of Calliandra haematocephala.

    PubMed Central

    Brenner, S A; Romeo, J T

    1986-01-01

    Four saprophytic and pathogenic fungi were isolated from the leaf surface of Calliandra haematocephala, a tropical legume known to contain large amounts of rare nonprotein imino acids in its leaves and seeds. The fungi Aspergillus niger, Aspergillus sp., Curvularia sp., and Penicillium sp. were cultured in the laboratory and tested for susceptibility to leaf extracts of the host plant and to proline, pipecolic acid, cis-5-hydroxypipecolic acid, and 2,4-trans-4,5-cis-4,5-dihydroxypipecolic acid. Fungal spore germination and germ tube growth were measured. Aspergillus sp. was inhibited by plant extracts and by pipecolic acid and cis-5-hydroxypipecolic acid. Curvularia sp. growth was stimulated by plant extracts and by pipecolic acid. The other two fungi were unaffected by any of the treatments. The data indicate that imino acids may play a role in the specific resistance of Calliandra spp. to Aspergillus sp. PMID:3707119

  13. Effects of food surface topography on phage-based magnetoelastic biosensor detection

    NASA Astrophysics Data System (ADS)

    Horikawa, Shin; Chai, Yating; Zhao, Ruiting; Wikle, Howard C.; Chin, Bryan A.

    2014-05-01

    Phage-based magnetoelastic (ME) biosensors have proven useful in rapidly and inexpensively detecting food surface con- tamination. These biosensors are wireless, mass-sensitive biosensors and can be placed directly on food surfaces to detect the presence of target pathogens. Previously, millimeter-scale strip-shaped ME biosensors have been used to demonstrate direct detection of Salmonella Typhimurium on various fresh produce surfaces, including tomatoes, shell eggs, watermel- ons, and spinach leaves. Since the topography of these produce surfaces are different, and the biosensor must come into direct contact with Salmonella bacteria, food surfaces with large roughness and curvatures (e.g., spinach leaf surfaces) may allow the bacteria to avoid direct contact, thereby avoiding detection. The primary objective of this paper is, hence, to investigate the effects of food surface topography on the detection capabilities of the biosensors. Spinach leaf surfaces were selected as model surfaces, and detection experiments were conducted with differently sized biosensors (2 mm, 0.5 mm, and 150 μm in length). Spinach leaf roughness and curvatures of both adaxial (top) and abaxial (underside) surfaces were measured using a confocal laser scanning microscope. The experimental results showed that in spinach as the sen- sor was made smaller, the physical contact between the biosensors and bacteria were improved. Smaller sensors thereby enhance detection capabilities. When proper numbers of biosensors are used, micron-scale biosensors are anticipated to yield improved limits of detection over previously investigated millimeter-scale biosensors.

  14. Optical coherence tomography biospeckle imaging for fast monitoring varying surface responses of a plant leaf under ozone stress

    NASA Astrophysics Data System (ADS)

    Srimal, L. K. T.; Kadono, H.; Rajagopalan, U. M.

    2013-05-01

    In this study, Optical Coherence Tomography (OCT) was used to investigate the effect of short term ozone exposure on both front and back surfaces of the leaves of Allium tuberosum plant. Plant leaves were subjected to treat with 240ppb level of ozone, and imaging data were acquired from back and front surfaces of the leaves. Variations of the biological activations were monitored based on the biospeckles. Standard deviations (SD) of OCT temporal signal at each point were calculated and used to visualize the effect of ozone exposure. Leaf back surface showed higher SDs in biospeckle OCT signal in comparison to these of the front surface. These observations prove that the short term ozone stress on plant can be investigated successively with biospeckle OCT imaging technique.

  15. Epidemiology and Control of Strawberry Bacterial Angular Leaf Spot Disease Caused by Xanthomonas fragariae.

    PubMed

    Kim, Da-Ran; Gang, Gun-Hye; Jeon, Chang-Wook; Kang, Nam Jun; Lee, Sang-Woo; Kwak, Youn-Sig

    2016-08-01

    Strawberry bacterial angular leaf spot (ALS) disease, caused by Xanthomonas fragariae has become increasingly problematic in the strawberry agro-industry. ALS causes small angular water-soaked lesions to develop on the abaxial leaf surface. Studies reported optimum temperature conditions for X. fragariae are 20°C and the pathogen suffers mortality above 32°C. However, at the nursery stage, disease symptoms have been observed under high temperature conditions. In the present study, results showed X. fragariae transmission was via infected maternal plants, precipitation, and sprinkler irrigation systems. Systemic infections were detected using X. fragariae specific primers 245A/B and 295A/B, where 300-bp and 615-bp were respectively amplified. During the nursery stage (from May to August), the pathogen was PCR detected only in maternal plants, but not in soil or irrigation water through the nursery stage. During the cultivation period, from September to March, the pathogen was detected in maternal plants, progeny, and soil, but not in water. Additionally, un-infected plants, when planted with infected plants were positive for X. fragariae via PCR at the late cultivation stage. Chemical control for X. fragariae with oxolinic acid showed 87% control effects against the disease during the nursery period, in contrast to validamycin-A, which exhibited increased efficacy against the disease during the cultivation stage (control effect 95%). To our knowledge, this is the first epidemiological study of X. fragariae in Korean strawberry fields. PMID:27493604

  16. Epidemiology and Control of Strawberry Bacterial Angular Leaf Spot Disease Caused by Xanthomonas fragariae

    PubMed Central

    Kim, Da-Ran; Gang, Gun-hye; Jeon, Chang-Wook; Kang, Nam Jun; Lee, Sang-woo; Kwak, Youn-Sig

    2016-01-01

    Strawberry bacterial angular leaf spot (ALS) disease, caused by Xanthomonas fragariae has become increasingly problematic in the strawberry agro-industry. ALS causes small angular water-soaked lesions to develop on the abaxial leaf surface. Studies reported optimum temperature conditions for X. fragariae are 20°C and the pathogen suffers mortality above 32°C. However, at the nursery stage, disease symptoms have been observed under high temperature conditions. In the present study, results showed X. fragariae transmission was via infected maternal plants, precipitation, and sprinkler irrigation systems. Systemic infections were detected using X. fragariae specific primers 245A/B and 295A/B, where 300-bp and 615-bp were respectively amplified. During the nursery stage (from May to August), the pathogen was PCR detected only in maternal plants, but not in soil or irrigation water through the nursery stage. During the cultivation period, from September to March, the pathogen was detected in maternal plants, progeny, and soil, but not in water. Additionally, un-infected plants, when planted with infected plants were positive for X. fragariae via PCR at the late cultivation stage. Chemical control for X. fragariae with oxolinic acid showed 87% control effects against the disease during the nursery period, in contrast to validamycin-A, which exhibited increased efficacy against the disease during the cultivation stage (control effect 95%). To our knowledge, this is the first epidemiological study of X. fragariae in Korean strawberry fields. PMID:27493604

  17. Defending the leaf surface: intra- and inter-specific differences in silicon deposition in grasses in response to damage and silicon supply

    PubMed Central

    Hartley, Sue E.; Fitt, Rob N.; McLarnon, Emma L.; Wade, Ruth N.

    2015-01-01

    Understanding interactions between grasses and their herbivores is central to the conservation of species-rich grasslands and the protection of our most important crops against pests. Grasses employ a range of defenses against their natural enemies; silicon-based defenses have been shown to be one of the most effective. Silicon (Si) is laid down on the leaf surface as spines and other sharp bodies, known as phytoliths, making grasses abrasive and their foliage indigestible to herbivores. Previous studies on Si defenses found that closely related species may have similar levels of Si in the leaves but differ markedly in abrasiveness. Here we show how the number, shape and distribution of Si-rich phytoliths and spines differ within and between different grass species and demonstrate that species also differ in their ability to change the deposition and distribution of these defenses in response to damage or increases in Si supply. Specifically, we tested the response of two genotypes of Festuca arundinacea known to differ in their surface texture and three different grass species (F. ovina, F. rubra, and Deschampsia cespitosa) differing in their abrasiveness to combined manipulation of leaf damage and Si supply. F. arundinacea plants with a harsh leaf surface had higher Si content and more spines on their leaf surface than soft varieties. F. ovina and D. cespitosa plants increased their leaf Si concentration and produced an increase in the number of leaf spines and phytoliths on the leaf surface in response to Si addition. F rubra also increased leaf Si content in response to treatments, particularly in damaged leaves, but did not deposit this in the form of spines or increased densities of phytoliths. We discuss how the form in which grasses deposit Si may affect their anti-herbivore characteristics and consider the ecological and agricultural implications of the differences in allocation to Si-based defenses between grass species. PMID:25717331

  18. The Effect of Leaf Litter Cover on Surface Runoff and Soil Erosion in Northern China

    PubMed Central

    Li, Xiang; Niu, Jianzhi; Xie, Baoyuan

    2014-01-01

    The role of leaf litter in hydrological processes and soil erosion of forest ecosystems is poorly understood. A field experiment was conducted under simulated rainfall in runoff plots with a slope of 10%. Two common types of litter in North China (from Quercus variabilis, representing broadleaf litter, and Pinus tabulaeformis, representing needle leaf litter), four amounts of litter, and five rainfall intensities were tested. Results revealed that the litter reduced runoff and delayed the beginning of runoff, but significantly reduced soil loss (p<0.05). Average runoff yield was 29.5% and 31.3% less than bare-soil plot, and for Q. variabilis and P. tabulaeformis, respectively, and average sediment yield was 85.1% and 79.9% lower. Rainfall intensity significantly affected runoff (R = 0.99, p<0.05), and the efficiency in runoff reduction by litter decreased considerably. Runoff yield and the runoff coefficient increased dramatically by 72.9 and 5.4 times, respectively. The period of time before runoff appeared decreased approximately 96.7% when rainfall intensity increased from 5.7 to 75.6 mm h−1. Broadleaf and needle leaf litter showed similarly relevant effects on runoff and soil erosion control, since no significant differences (p≤0.05) were observed in runoff and sediment variables between two litter-covered plots. In contrast, litter mass was probably not a main factor in determining runoff and sediment because a significant correlation was found only with sediment in Q. variabilis litter plot. Finally, runoff yield was significantly correlated (p<0.05) with sediment yield. These results suggest that the protective role of leaf litter in runoff and erosion processes was crucial, and both rainfall intensity and litter characteristics had an impact on these processes. PMID:25232858

  19. Real-time mapping of salt glands on the leaf surface of Cynodon dactylon L. using scanning electrochemical microscopy.

    PubMed

    Parthasarathy, Meera; Pemaiah, Brindha; Natesan, Ravichandran; Padmavathy, Saralla R; Pachiappan, Jayaraman

    2015-02-01

    Salt glands are specialized organelles present in the leaf tissues of halophytes, which impart salt-tolerance capability to the plant species. These glands are usually identified only by their morphology using conventional staining procedures coupled with optical microscopy. In this work, we have employed scanning electrochemical microscopy to identify the salt glands not only by their morphology but also by their salt excretion behavior. Bermuda grass (Cynodon dactylon L.) species was chosen for the study as they are known to be salt-tolerant and contain salt glands on leaf surfaces. Scanning electrochemical microscopy performed in sodium chloride medium in the presence and absence of potassium ferrocyanide as redox mediator, reveals the identity of salt glands. More insight into the ion expulsion behavior of these glands was obtained by mapping lateral and vertical variations in ion concentrations using surface impedance measurements which indicated five times higher resistance over the salt glands compared to the surrounding tissues and bulk solution. The protocol could be used to understand the developmental processes in plants grown in different soil/water conditions in order to improve salt tolerance of food crops by genetic engineering and hence improve their agricultural productivity. PMID:25460612

  20. Optimization of Total Flavonoid Compound Extraction from Gynura medica Leaf Using Response Surface Methodology and Chemical Composition Analysis

    PubMed Central

    Liu, Wei; Yu, Yanying; Yang, Ruzhen; Wan, Chunpeng; Xu, Binbin; Cao, Shuwen

    2010-01-01

    Optimization of total flavonoid compound (TFC) extraction from Gynura medica leaf was investigated using response surface methodology (RSM) in this paper. The conditions investigated were 30–60% (v/v) ethanol concentration (X1), 85–95 °C extraction temperature (X2) and 30–50 (v/w) liquid-to-solid ratio (X3). Statistical analysis of the experiments indicated that temperature and liquid-to-solid ratio significantly affected TFC extraction (p < 0.01). The Box-Behnken experiment design showed that polynomial regression models were in good agreement with the experimental results, with the coefficients of determination of 0.9325 for TFC yield. The optimal conditions for maximum TFC yield were 55% ethanol, 92 °C and 50 (v/w) liquid-to-solid ratio with a 30 min extraction time. Extracts from these conditions showed a moderate antioxidant value of 54.78 μmol quercetin/g dry material (DM), 137.3 μmol trolox/g DM for 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 108.21 μmol quercetin/g DM, 242.31 μmol trolox/g DM for 2,2-azino-bis-(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS+), respectively. HPLC-DAD-MS analysis showed that kaempferol-3-O-glucoside was the principal flavonoid compound in Gynura medica leaf. PMID:21151469

  1. Fabrication of lotus-leaf-like superhydrophobic surfaces via Ni-based nano-composite electro-brush plating

    NASA Astrophysics Data System (ADS)

    Liu, Hongtao; Wang, Xuemei; Ji, Hongmin

    2014-01-01

    Superhydrophobic surface has become a research hot topic in recent years due to its excellent performance and wide application prospect. This paper investigates the method to fabricate superhydrophobic surface on carbon steel substrate via two-layer nano-composite electro-brush plating and subsequent surface modification with low free energy materials. The hydrophobic properties of as-prepared coatings were characterized by a water sliding angle (SA) and a water contact angle (CA) measured by the Surface tension instrument. A Scanning electron microscope was used to analyze the surface structure of plating coatings. Anti-corrosion performance of the superhydrophobic coating was characterized by a potentiodynamic polarization curve measured by the Electrochemical workstation. The research result shows that: the superhydrophobic structure can be successfully prepared by plating nano-C/Ni and nano-Cu/Ni two-layer coating on carbon steel substrate under appropriate technology and has similarity with lotus-leaf-like micro/nano composite structure; the contact angle of the as-prepared superhydrophobic coating can be up to 155.5°, the sliding angle is 5°; the coating has better anti-corrosion performance compared with substrate.

  2. Improving winter leaf area index estimation in coniferous forests and its significance in estimating the land surface albedo

    NASA Astrophysics Data System (ADS)

    Wang, Rong; Chen, Jing M.; Pavlic, Goran; Arain, Altaf

    2016-09-01

    Winter leaf area index (LAI) of evergreen coniferous forests exerts strong control on the interception of snow, snowmelt and energy balance. Simulation of winter LAI and associated winter processes in land surface models is challenging. Retrieving winter LAI from remote sensing data is difficult due to cloud contamination, poor illumination, lower solar elevation and higher radiation reflection by snow background. Underestimated winter LAI in evergreen coniferous forests is one of the major issues limiting the application of current remote sensing LAI products. It has not been fully addressed in past studies in the literature. In this study, we used needle lifespan to correct winter LAI in a remote sensing product developed by the University of Toronto. For the validation purpose, the corrected winter LAI was then used to calculate land surface albedo at five FLUXNET coniferous forests in Canada. The RMSE and bias values for estimated albedo were 0.05 and 0.011, respectively, for all sites. The albedo map over coniferous forests across Canada produced with corrected winter LAI showed much better agreement with the GLASS (Global LAnd Surface Satellites) albedo product than the one produced with uncorrected winter LAI. The results revealed that the corrected winter LAI yielded much greater accuracy in simulating land surface albedo, making the new LAI product an improvement over the original one. Our study will help to increase the usability of remote sensing LAI products in land surface energy budget modeling.

  3. Leaf shrinkage: a predictive indicator of the potential variation of the surface area-to-volume ratio according to the leaf moisture content.

    PubMed

    Essaghi, Salaheddine; Hachmi, M'hamed; Yessef, Mohammed; Dehhaoui, Mohammed

    2016-01-01

    Leaf shrinkage provides insights into the potential variation of foliar SVR, within the same species, when leaf moisture content is changing in response to water deficit. Since SVR is among the most significant plant flammability features, leaf shrinkage would be a relevant component of fuel hazard assessment through its influence on SVR, enhancing-if it is taken into account-thereby the wildfire prediction accuracy. The purpose of this work is, first, to consider the leaf shrinkage by characterizing the plant species towards the shrinkability of their leaves, taking account the possible site effect, to characterize the behavior of shrinkage as a function of moisture content and finally to perform a classification for some dominant Mediterranean species based on the shrinkage levels. The assessment of the hierarchical relationships between the dimensional shrinkages is also aimed. Leaves and needles of thirteen tree and shrub species were harvested from six different sites in western Rif Mountains. Leaves dimensions and moisture content were measured regularly during a gradual drying at the laboratory. Dimensional shrinkages were calculated at each moisture content level. Dimensional shrinkages behaved similarly whether in leaf or timber and kept the same reporting relationships between each other. Among the species sampled in different sites, site effect is significant only in Pinus canariensis and Pistacia lentiscus. A classification of the plant species was carried out in three separate classes. Generally, shrinkage class of the plant species studied gave an idea on its flammability ranking reported in the literature, implying thus a cause-and-effect relationship between both parameters. PMID:27536513

  4. Grazing exit micro X-ray fluorescence analysis of a hazardous metal attached to a plant leaf surface using an X-ray absorber method.

    PubMed

    Awane, Tohru; Fukuoka, Shintaro; Nakamachi, Kazuo; Tsuji, Kouichi

    2009-05-01

    If human beings or animals repeatedly ingest plant leaves contaminated with minute quantities of hazardous metals (Pb, As, Hg, Cd, etc.), the metals will gradually accumulate in their bodies. When the quantities of the metals in the bodies reach toxic levels, they may cause serious symptoms of poisoning. Therefore, it is significant to detect and analyze the minute quantities of hazardous metals that attach to plant leaves in terms of epidemiology and disease prevention. We developed grazing exit micro X-ray fluorescence analysis (GE-micro-XRF), which was expected to analyze the localized surface of an aqueous plant leaf with a much faster and simpler sample treatment than with conventional analytical methods, to detect Pb attached to a surface of a leaf of Camellia hiemalis. A micro X-ray beam was produced by using a polycapillary X-ray lens. GE-v-XRF is a grazing exit X-ray analysis (GE-XA) method in which X-rays emitted from only the near-surface region of a specimen are selectively detected under a grazing exit angle condition (extremely low exit angle near 0 degrees). In any GE-XA method, X-rays emitted from inside the specimen must be absorbed inside the specimen and attenuated when X-rays pass through the specimen. However, we deduced that X-rays emitted from inside aqueous organic material such as a plant leaf are scarcely absorbed because X-ray absorption in any aqueous organic material is much smaller than that in most metallic and semiconductor materials, which was analyzed with GE-XA methods. Therefore, we have developed a novel GE-micro-XRF method in which a chip of a silicon wafer is placed between the analyzed leaf and an X-ray detector as an absorber of the X-rays emitted from inside the leaf. As a result of GE-XRF analysis of a leaf dipped in Pb standard solution using the X-ray absorber, we have for the first time selectively detected X-rays emitted from the near-surface region of an aqueous plant leaf. Therefore, we have detected X-rays emitted

  5. Superhydrophobic surfaces fabricated by femtosecond laser with tunable water adhesion: from lotus leaf to rose petal.

    PubMed

    Long, Jiangyou; Fan, Peixun; Gong, Dingwei; Jiang, Dafa; Zhang, Hongjun; Li, Lin; Zhong, Minlin

    2015-05-13

    Superhydrophobic surfaces with tunable water adhesion have attracted much interest in fundamental research and practical applications. In this paper, we used a simple method to fabricate superhydrophobic surfaces with tunable water adhesion. Periodic microstructures with different topographies were fabricated on copper surface via femtosecond (fs) laser irradiation. The topography of these microstructures can be controlled by simply changing the scanning speed of the laser beam. After surface chemical modification, these as-prepared surfaces showed superhydrophobicity combined with different adhesion to water. Surfaces with deep microstructures showed self-cleaning properties with extremely low water adhesion, and the water adhesion increased when the surface microstructures became flat. The changes in surface water adhesion are attributed to the transition from Cassie state to Wenzel state. We also demonstrated that these superhydrophobic surfaces with different adhesion can be used for transferring small water droplets without any loss. We demonstrate that our approach provides a novel but simple way to tune the surface adhesion of superhydrophobic metallic surfaces for good potential applications in related areas. PMID:25906058

  6. Leaf surface structures enable the endemic Namib desert grass Stipagrostis sabulicola to irrigate itself with fog water

    PubMed Central

    Roth-Nebelsick, A.; Ebner, M.; Miranda, T.; Gottschalk, V.; Voigt, D.; Gorb, S.; Stegmaier, T.; Sarsour, J.; Linke, M.; Konrad, W.

    2012-01-01

    The Namib grass Stipagrostis sabulicola relies, to a large degree, upon fog for its water supply and is able to guide collected water towards the plant base. This directed irrigation of the plant base allows an efficient and rapid uptake of the fog water by the shallow roots. In this contribution, the mechanisms for this directed water flow are analysed. Stipagrostis sabulicola has a highly irregular surface. Advancing contact angle is 98° ± 5° and the receding angle is 56° ± 9°, with a mean of both values of approximately 77°. The surface is thus not hydrophobic, shows a substantial contact angle hysteresis and therefore, allows the development of pinned drops of a substantial size. The key factor for the water conduction is the presence of grooves within the leaf surface that run parallel to the long axis of the plant. These grooves provide a guided downslide of drops that have exceeded the maximum size for attachment. It also leads to a minimum of inefficient drop scattering around the plant. The combination of these surface traits together with the tall and upright stature of S. sabulicola contributes to a highly efficient natural fog-collecting system that enables this species to thrive in a hyperarid environment. PMID:22356817

  7. [Leaf micrografic anatomy of the Neotropical palm Bactris gasipaes (Arecaceae)].

    PubMed

    Chaimsohn, Francisco Paulo; Montiel, Mayra; Villalobos, Enrique; Mora Urpi, Jorge

    2008-06-01

    The economic importance of the palm Bactris gasipaes is growing in the Neotropoical region. We collected leaflets from plants under a chemical fertilization regime and a population of 5000 plants per hectare, in Costa Rica. The variety, Diamantes 10, has an ascendency fom the upper Amazon basin. We used Harries hematoxiline, eocine and standard light microscopy techniques. The presence of raphids and buliform cells was confirmed for the abaxial surface of the leaflets and for the hypodermic tissue on both sides. The absence of the Krantz anatomy was confirmed in consistence with former observations about the C3 photosynthesis in other species of Palmaceae. The average stomatal density on the abaxial surface was 96.87 +/- 16.31 stomata.mm(-2) and 14.20 +/- 4.05 in the adaxial surface. PMID:19256456

  8. Leaf-derived cecidomyiid galls are sinks in Machilus thunbergii (Lauraceae) leaves.

    PubMed

    Huang, Meng-Yuan; Huang, Wen-Dar; Chou, Hsueh-Mei; Lin, Kuan-Hung; Chen, Chang-Chang; Chen, Pei-Ju; Chang, Yung-Ta; Yang, Chi-Ming

    2014-11-01

    Three relevant hypotheses - nutrition, environment and the enemies hypothesis - often invoked to explore source and sink relationships between galls and their host plants are still under dispute. In this research, chlorophyll fluorescence, gas exchange capacity, stomatal conductance, total carbon and nitrogen, total soluble sugars and starches, and scanning and transmission electron microscopy of two types of galls were used to investigate source-sink relationships. Compared with host leaves, these galls demonstrated slightly lower chlorophyll fluorescence; however, gas exchange capacity and stomatal conductance were not detected at all. Scanning electron micrographs demonstrated that the abaxial epidermis of host leaves contain normal amounts of stomata, whereas no stomata were observed on the exterior and interior surfaces of both types of galls. In addition, gall inner surfaces were covered with many kinds of fungal hyphae. Gall total carbon (C) and nitrogen (N) levels were lower but the C/N ratio was higher in galls than host leaves. Both types of galls accumulated higher total soluble sugars and starches than host leaves. Transmission electron micrographs also revealed that both types of galls contain plastoglobuli and giant starch granules during gall development. Results strongly indicate that leaf-derived cecidomyiid galls are sinks in Machilus thunbergii leaves. However, it is perplexing how larvae cycle and balance CO(2) and O(2) in gall growth chambers without stomata. PMID:24621096

  9. Elucidating the role of transport processes in leaf glucosinolate distribution.

    PubMed

    Madsen, Svend Roesen; Olsen, Carl Erik; Nour-Eldin, Hussam Hassan; Halkier, Barbara Ann

    2014-11-01

    In Arabidopsis (Arabidopsis thaliana), a strategy to defend its leaves against herbivores is to accumulate glucosinolates along the midrib and at the margin. Although it is generally assumed that glucosinolates are synthesized along the vasculature in an Arabidopsis leaf, thereby suggesting that the margin accumulation is established through transport, little is known about these transport processes. Here, we show through leaf apoplastic fluid analysis and glucosinolate feeding experiments that two glucosinolate transporters, GTR1 and GTR2, essential for long-distance transport of glucosinolates in Arabidopsis, also play key roles in glucosinolate allocation within a mature leaf by effectively importing apoplastically localized glucosinolates into appropriate cells. Detection of glucosinolates in root xylem sap unambiguously shows that this transport route is involved in root-to-shoot glucosinolate allocation. Detailed leaf dissections show that in the absence of GTR1 and GTR2 transport activity, glucosinolates accumulate predominantly in leaf margins and leaf tips. Furthermore, we show that glucosinolates accumulate in the leaf abaxial epidermis in a GTR-independent manner. Based on our results, we propose a model for how glucosinolates accumulate in the leaf margin and epidermis, which includes symplasmic movement through plasmodesmata, coupled with the activity of putative vacuolar glucosinolate importers in these peripheral cell layers. PMID:25209984

  10. Optimising the prognostic leaf phenology of a land surface model at a global scale: perspectives and challenges

    NASA Astrophysics Data System (ADS)

    MacBean, Natasha; Maignan, Fabienne; Peylin, Philippe; Bacour, Cédric

    2014-05-01

    Leaf phenology is a critical component of the coupled soil-vegetation-atmosphere system as it directly controls the spatial and temporal variability of the surface carbon, water and energy fluxes. The length of the growing season governs the net amount of carbon that is assimilated and released through photosynthesis and autotrophic respiration, as well as affecting the surface energy balance and hydrology through changing albedo, surface roughness and evapotranspiration, which in turn regulate the land surface temperature and moisture conditions. These provide a strong constraint on atmospheric boundary layer conditions and circulation, with possible important long-term impacts on the climate. A recent study (Richardson et al., 2012) showed that there is bias in the growing season length (GSL) predicted by many Land Surface Models (LSMs) when compared to observations. However, prior to parameter optimisation it is unclear whether the model-data misfit is the result of inaccurate parameter values or model structural error. Here satellite-derived NDVI data are used to constrain the phenology parameters in the ORCHIDEE LSM. A 4D-variational multi-site data assimilation system is used to optimise parameters that directly control the leaf phenology models of all natural deciduous PFTs in ORCHIDEE. The resultant parameter vectors are validated both temporally and spatially, both at site and global scales. The ability of the satellite data to improve the seasonal C fluxes is evaluated with in situ net CO2 fluxes and atmospheric CO2 data, and the improvement in the inter-annual variability of the GSL is discussed. The impact of the optimisations on the coupled water and energy budgets is also examined. Technical issues are also addressed, including the ability of the multi-site DA system to retrieve PFT-generic parameter vectors at a global scale, the difficulty of finding a unique parameter vector, especially for parameters involved in threshold responses, and the issue

  11. COMPARATIVE DISAPPEARANCE OF DIOXATHION, MALATHION, OXYDEMETONMETHYL AND DIALIFOR FROM FLORIDA CITRUS LEAF AND FRUIT SURFACES

    EPA Science Inventory

    Surface residue disappearance rates of dioxathion, malathion, and oxydemetonmethyl, and dialifor were the same for fruit and leaves, and they increase with temperature. Disappearance rates were in the order of malation, oxydemetonmethyl, dialifor, dioxathion (from largest to smal...

  12. Leaf Area Index Estimation in Vineyards from Uav Hyperspectral Data, 2d Image Mosaics and 3d Canopy Surface Models

    NASA Astrophysics Data System (ADS)

    Kalisperakis, I.; Stentoumis, Ch.; Grammatikopoulos, L.; Karantzalos, K.

    2015-08-01

    The indirect estimation of leaf area index (LAI) in large spatial scales is crucial for several environmental and agricultural applications. To this end, in this paper, we compare and evaluate LAI estimation in vineyards from different UAV imaging datasets. In particular, canopy levels were estimated from i.e., (i) hyperspectral data, (ii) 2D RGB orthophotomosaics and (iii) 3D crop surface models. The computed canopy levels have been used to establish relationships with the measured LAI (ground truth) from several vines in Nemea, Greece. The overall evaluation indicated that the estimated canopy levels were correlated (r2 > 73%) with the in-situ, ground truth LAI measurements. As expected the lowest correlations were derived from the calculated greenness levels from the 2D RGB orthomosaics. The highest correlation rates were established with the hyperspectral canopy greenness and the 3D canopy surface models. For the later the accurate detection of canopy, soil and other materials in between the vine rows is required. All approaches tend to overestimate LAI in cases with sparse, weak, unhealthy plants and canopy.

  13. ESTIMATION OF LAND SURFACE BROADBAND ALBEDOS AND LEAF AREA INDEX FROM EO-1 DATA AND VALIDATION

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Advanced Land Imager (ALI) is a multispectral sensor onboard NASA Earth Observer-1 (EO-1). It has similar spatial resolution to the Landsat-7 Enhanced Thematic Mapper Plus (ETM+), with three additional spectral bands. We developed new algorithms for estimating both land surface broadband albedo...

  14. The utility of Bambusoideae (Poaceae, Poales) leaf blade anatomy for identification and systematics.

    PubMed

    Leandro, T D; Shirasuna, R T; Filgueiras, T S; Scatena, V L

    2016-04-19

    Bambusoideae is a diverse subfamily that includes herbaceous (Olyreae) and woody (Arundinarieae and Bambuseae) bamboos. Species within Bambusae are particularly difficult to identify due to their monocarpic lifecycle and the often long durations between mass flowering events; whereas the herbaceous bamboos are pluricarpic, but often are found with no reproductive structures. The leaf blade anatomy of 16 sympatric species of native Brazilian bamboos (Olyreae and Bambuseae) from the Atlantic Rainforest was studied in order to detect useful features for their identification. All the studied species share the following features: epidermis with a single stratum of cells; adaxial bulliform cells; mesophyll with arm cells, rosette cells, and fusoid cells; and collateral vascular bundles. Herbaceous bamboos share two features: papillae scattered on the abaxial surface and parallel-sided arrays of bulliform cells; whereas woody bamboos share: centrally organized papillae and fan-shaped arrays of bulliform cells. Also within the woody bamboos, intercostal fibers and a midrib with only one vascular bundle (simple midrib) characterize the subtribe Arthrostylidiinae; whereas a midrib with more than one vascular bundle (complex midrib) and a stomatal apparatus with two pappilae per subsidiary cell characterize the subtribe Chusqueinae. There are also diagnostic features for the sampled species, such as: papillae shape, and the outline and structure of the midrib. An identification key for all the studied species is provided based on the anatomical features. PMID:27097081

  15. Acquisition and diversification of cladodes: leaf-like organs in the genus Asparagus.

    PubMed

    Nakayama, Hokuto; Yamaguchi, Takahiro; Tsukaya, Hirokazu

    2012-03-01

    The genus Asparagus is unusual in producing axillary, determinate organs called cladodes, which may take on either a flattened or cylindrical form. Here, we investigated the evolution of cladodes to elucidate the mechanisms at play in the diversification of shoot morphology. Our observations of Asparagus asparagoides, which has leaf-like cladodes, showed that its cladodes are anatomically and developmentally similar to leaves but differ in the adaxial/abaxial polarity of the vasculature. In addition to the expression of an ortholog of KNAT1, orthologous genes that are normally expressed in leaves, asymmetric leaves1 and HD-ZIPIII, were found to be expressed in cladode primordia in a leaf-like manner. The cylindrical cladodes of Asparagus officinalis showed largely similar expression patterns but showed evidence of being genetically abaxialized. These results provide evidence that cladodes are modified axillary shoots, suggest that the co-option of preexisting gene networks involved in leaf development transferred the leaf-like form to axillary shoots, and imply that altered expression of leaf polarity genes led to the evolution of cylindrical cladodes in the A. officinalis clade. PMID:22415273

  16. IR reflection spectra of the silicate surface layer of yellowed rice plant leaf

    NASA Astrophysics Data System (ADS)

    Sato, Kenzo

    1986-09-01

    We have investigated the IR reflectional properties of the three-hold cytrogical surface layer (kutchikura layer on silicate layer n(SiO2) on silicate cellulose layer C6H10SixOy) and that of chlorophyll, a(C55H72MgN4O5) etc., present in bladder's cells by using our experimental method. From analysis of three set of anisotropical reflection spectra assigned as due to CO, SiO and NC surface oscillators contained in the cytrogical cells and measured at 2500 2200 cm-1, 1200 700 cm-1 and at 700 200 cm-1 regions, we have confirmed some important results. One is their quantized directional distributions that of the numbers of fine step spectrum and that of the reflection integrals of these spectra. Here, that of the NC oscillators were found to distribute in pentagonal directions relating to the molecular structure of chlorophyll. Second, we confirmed the pecularity of eight fine step-series measured in these sensitive spectra comparing with that of bamboo's seven series. Third, from analysis of the stepnized variation of the “reflection integrals”, we estimated the origin of this effect as which is presumably due to statistical, transfer of the 2p4 valence electrons etc. in the oxygen atoms from C=O, Si=O double bonding side upto the shallower quantized states, E(N,J) which were formed softly around the MediaObjects/10762_2005_BF01012055_f1.tif and MediaObjects/10762_2005_BF01012055_f2.tif surface oscillators. And these surface oscillators were confirmed as to make photo-chemical reaction process by receiving energy higher than ˜24 m eV especially under the illumination of sunshine etc.

  17. Physical and mechanical properties of spinach for whole-surface online imaging inspection

    NASA Astrophysics Data System (ADS)

    Tang, Xiuying; Mo, Chang Y.; Chan, Diane E.; Peng, Yankun; Qin, Jianwei; Yang, Chun-Chieh; Kim, Moon S.; Chao, Kuanglin

    2011-06-01

    The physical and mechanical properties of baby spinach were investigated, including density, Young's modulus, fracture strength, and friction coefficient. The average apparent density of baby spinach leaves was 0.5666 g/mm3. The tensile tests were performed using parallel, perpendicular, and diagonal directions with respect to the midrib of each leaf. The test results showed that the mechanical properties of spinach are anisotropic. For the parallel, diagonal, and perpendicular test directions, the average values for the Young's modulus values were found to be 2.137MPa, 1.0841 MPa, and 0.3914 MPa, respectively, and the average fracture strength values were 0.2429 MPa, 0.1396 MPa, and 0.1113 MPa, respectively. The static and kinetic friction coefficient between the baby spinach and conveyor belt were researched, whose test results showed that the average coefficients of kinetic and maximum static friction between the adaxial (front side) spinach leaf surface and conveyor belt were 1.2737 and 1.3635, respectively, and between the abaxial (back side) spinach leaf surface and conveyor belt were 1.1780 and 1.2451 respectively. These works provide the basis for future development of a whole-surface online imaging inspection system that can be used by the commercial vegetable processing industry to reduce food safety risks.

  18. Attachment of Escherichia coli O157:H7 to lettuce leaf surface and bacterial viability in response to chlorine treatment as demonstrated by using confocal scanning laser microscopy.

    PubMed

    Seo, K H; Frank, J F

    1999-01-01

    Confocal scanning laser microscopy was used to observe the location of Escherichia coli O157:H7 on and within lettuce leaves. Sections of leaves (ca. 0.5 by 0.5 cm) were inoculated by submersion in a suspension of E. coli O157:H7 (ca. 10(7) to 10(8) CFU/ml) overnight at 7 degrees C. Fluorescein isothiocyanate-labeled antibody was used to visualize the attached bacteria. E. coli O157:H7 was found attached to the surface, trichomes, stomata, and cut edges. Three-dimensional volume reconstruction of interior portions of leaves showed that E. coli O157:H7 was entrapped 20 to 100 microm below the surface in stomata and cut edges. Agar plate culturing and microscopic observation indicated that E. coli O157:H7 preferentially attached to cut edges, as opposed to the intact leaf surface. Dual staining with fluorescein isothiocyanate-labeled antibody and propidium iodide was used to determine viability of cells on artificially contaminated lettuce leaves after treatment with 20 mg/liter chlorine solution for 5 min. Many live cells were found in stomata and on cut edges following chlorine treatment. E. coli O157:H7 did not preferentially adhere to biofilm produced by Pseudomonas fluorescens on the leaf surface. In contrast to E. coli O157:H7, Pseudomonas adhered to and grew mainly on the intact leaf surface rather than on the cut edges. PMID:9921820

  19. Disruption of N-Αcyl Homoserine Lactone-Mediated Cell Signaling and Iron Acquisition in Epiphytic Bacteria by Leaf Surface Compounds▿

    PubMed Central

    Karamanoli, Katerina; Lindow, Steven E.

    2006-01-01

    Since N-acyl homoserine lactones (AHLs) are key mediators of cell density-dependent regulation of traits involved in virulence and epiphytic fitness in gram-negative bacteria such as Pseudomonas syringae, a variety of plant species were examined to determine their production of leaf surface compounds that could interact with these signaling systems. Leaf washings of 17 of 52 plant species tested stimulated or inhibited AHL-dependent traits in at least one of the bacterial reporter strains used. The active compounds from most plants could be distinguished from known AHLs due to different patterns of mobility during C8 and C18 reverse-phase thin-layer chromatography (TLC) and normal-phase TLC compared to the patterns for authentic bacterial AHLs. All plant extracts were also tested to determine their abilities to sequester iron and trigger bacterial siderophore synthesis on a medium containing abundant iron. Leaf washings from 16 of the 52 plant species, as well as tannic acid solutions, stimulated pyoverdine synthesis in P. syringae in a high-iron medium. These preparations also inhibited the growth of a P. syringae mutant unable to produce pyoverdine siderophores but not the growth of the wild-type bacterium. The stimulation of siderophore production and the growth inhibition by plant extracts and purified tannins were both reversed by addition of ferric chloride to culture media, indicating that iron was made unavailable by the compounds released onto the leaf surface. PMID:16997987

  20. Leaf surface lipophilic compounds as one of the factors of silver birch chemical defense against larvae of gypsy moth.

    PubMed

    Martemyanov, Vyacheslav V; Pavlushin, Sergey V; Dubovskiy, Ivan M; Belousova, Irina A; Yushkova, Yuliya V; Morosov, Sergey V; Chernyak, Elena I; Glupov, Victor V

    2015-01-01

    Plant chemical defense against herbivores is a complex process which involves a number of secondary compounds. It is known that the concentration of leaf surface lipophilic compounds (SLCs), particularly those of flavonoid aglycones are increased with the defoliation treatment of silver birch Betula pendula. In this study we investigated how the alteration of SLCs concentration in the food affects the fitness and innate immunity of the gypsy moth Lymantria dispar. We found that a low SLCs concentrations in consumed leaves led to a rapid larval development and increased females' pupae weight (= fecundity) compared to larvae fed with leaves with high SLCs content. Inversely, increasing the compounds concentration in an artificial diet produced the reverse effects: decreases in both larval weight and larval survival. Low SLCs concentrations in tree leaves differently affected larval innate immunity parameters. For both sexes, total hemocytes count in the hemolymph increased, while the activity of plasma phenoloxidase decreased when larvae consume leaves with reduced content of SLCs. Our results clearly demonstrate that the concentration of SLCs in silver birch leaves affects not only gypsy moth fitness but also their innate immune status which might alter the potential resistance of insects against infections and/or parasitoids. PMID:25816371

  1. Environmental controls on leaf wax δD ratios in surface peats across the monsoonal region of China

    NASA Astrophysics Data System (ADS)

    Huang, X.; Xue, J.; Wang, X.; Meyers, P. A.

    2015-09-01

    Leaf wax molecular and isotopic ratios are generally considered robust isotopic paleohydrologic proxies. Here we evaluate the proxy value of the molecular distributions and hydrogen isotopic compositions of long chain n-alkanes (δDalk) in surface peats collected from peatlands across a range of annual air temperatures from 1 to 15 °C and a range of annual mean precipitation from 720 to 2070 mm in the monsoonal region of China. The alkane ratios (ACL and CPI) and δDalk values show relatively large variations in multiple samples from a single site, highlighting the complexity of these ratios at a small spatial scale. In the montane Zoigê peatland, the apparent fractionation between precipitation and δDalk is more positive than in the other six sites, which is possibly an effect of the higher conductivity of the water in this high elevation site (3500 m a.s.l.). At a larger spatial scale, the site-averaged CPI ratios and the δDalk values of n-C29 and n-C31 alkanes show significant correlation with the air temperature and precipitation. These results support the application of the CPI ratio and the δDalk ratios of n-C29 and n-C31 alkanes as sensitive paleohydrologic proxies on millennial and larger timescales.

  2. Methods for Observing Microbial Biofilms Directly on Leaf Surfaces and Recovering Them for Isolation of Culturable Microorganisms

    PubMed Central

    Morris, C. E.; Monier, J.; Jacques, M.

    1997-01-01

    Epifluorescence microscopy, scanning electron microscopy, and confocal laser scanning microscopy were used to observe microbial biofilms directly on leaf surfaces. Biofilms were observed on leaves of all species sampled (spinach, lettuce, Chinese cabbage, celery, leeks, basil, parsley, and broad-leaved endive), although the epifluorescent images were clearest when pale green tissue or cuticle pieces were used. With these techniques, biofilms were observed that were about 20 (mu)m in depth and up to 1 mm in length and that contained copious exopolymeric matrices, diverse morphotypes of microorganisms, and debris. The epifluorescence techniques described here can be used to rapidly determine the abundance and localization of biofilms on leaves. An additional technique was developed to recover individual biofilms or portions of single biofilms from leaves and to disintegrate them for isolation of the culturable microorganisms they contained. Nineteen biofilms from broad-leaved endive, spinach, parsley, and olive leaves were thus isolated and characterized to illustrate the applications of this technique. PMID:16535579

  3. Leaf Area Influence on Surface Layer in a Deciduous Forest. Part I; Site Description

    NASA Technical Reports Server (NTRS)

    Sakai, Ricardo K.; Fitzjarrald, David R.; Moore, Kathleen E.; Sicker, John W.; Munger, William; Goulden, Michael L.; Wofsy, Steven C.

    1996-01-01

    A study over a deciduous forest located in middle Massachusetts (USA) has been performed to examine the role of leaves in the forest-atmosphere interaction. Due to the seasonal presence of leaves, a deciduous forest is a 'good laboratory' to study this interaction. In this first part, a description of a 30 m micrometeorological tower as well a qualitative description of some meteorological parameters are presented. The presence of leaves affects the forest in several ways. There is a decrease of upward PAR (Photosynthetically Active Radiation) due to absorption of visible light in the canopy. Water vapor concentration increases, and the CO2 concentration decreases in the surface layer as the canopy starts to be foliated. The physical presence of the leaves is felt in other quantities such as the global albedo and the subcanopy environment.

  4. Comprehensive study on the influence of evapotranspiration and albedo on surface temperature related to changes in the leaf area index

    NASA Astrophysics Data System (ADS)

    Zhu, Jiawen; Zeng, Xiaodong

    2015-07-01

    Many studies have investigated the influence of evapotranspiration and albedo and emphasize their separate effects but ignore their interactive influences by changing vegetation status in large amplitudes. This paper focuses on the comprehensive influence of evapotranspiration and albedo on surface temperature by changing the leaf area index (LAI) between 30°-90°N. Two LAI datasets with seasonally different amplitudes of vegetation change between 30°-90°N were used in the simulations. Seasonal differences between the results of the simulations are compared, and the major findings are as follows. (1) The interactive effects of evapotranspiration and albedo on surface temperature were different over different regions during three seasons [March-April-May (MAM), June-July-August (JJA), and September-October-November (SON)], i.e., they were always the same over the southeastern United States during these three seasons but were opposite over most regions between 30°-90°N during JJA. (2) Either evapotranspiration or albedo tended to be dominant over different areas and during different seasons. For example, evapotranspiration dominated almost all regions between 30°-90°N during JJA, whereas albedo played a dominant role over northwestern Eurasia during MAM and over central Eurasia during SON. (3) The response of evapotranspiration and albedo to an increase in LAI with different ranges showed different paces and signals. With relatively small amplitudes of increased LAI, the rate of the relative increase in evapotranspiration was quick, and positive changes happened in albedo. But both relative changes in evapotranspiration and albedo tended to be gentle, and the ratio of negative changes of albedo increased with relatively large increased amplitudes of LAI.

  5. Assimilation of leaf area index and surface soil moisture satellite observations into the SIM hydrological model over France

    NASA Astrophysics Data System (ADS)

    Fairbairn, David; Calvet, Jean-Christophe; Mahfouf, Jean-Francois; Barbu, Alina

    2016-04-01

    Hydrological models have a variety of uses, including flood and drought prediction and water management. The SAFRAN-ISBA-MODCOU (SIM) hydrological model consists of three stages: An atmospheric analysis (SAFRAN) over France, which forces a land surface model (ISBA-A-gs), which then provides drainage and runoff inputs to a hydrological model (MODCOU). The river discharge from MODCOU is validated using observed river discharge over France. Data assimilation (DA) combines a short model forecast from the past with observations to improve the estimate of the model state. The ISBA-A-gs representation of soil moisture and its influence by vegetation can be improved by assimilating surface soil moisture (SSM) and leaf area index (LAI) observations respectively. The Advanced Scatterometer (ASCAT) on board the MetOP satellite measures a low-frequency microwave signal, which is used to retrieve daily SSM over France. The SPOT-VGT sensor observes LAI over France at a temporal frequency of about 10 days. The Simplified Extended Kalman (SEKF) filter combines the model and observed variables by weighting them according to their respective accuracies. Although the SEKF makes incorrect linear assumptions, past experiments have shown that it improves on the model estimates of SSM and LAI. However, due to nonlinearities in the land surface model, improvements in SSM and LAI do not imply improved soil moisture fluxes (drainage, runoff and evapotranspiration). This study indirectly examines the impact of the SEKF on the soil moisture fluxes using the MODCOU hydrological model. The ISBA-A-gs model appears to underestimate the LAI for grasslands in winter and spring, which results in an underestimation (overestimation) of evapotranspiration (drainage and runoff). The excess water flowing into the rivers and aquifers contributes to an overestimation of the MODCOU discharge. Assimilating LAI observations slightly increases the LAI analysis in winter and spring and therefore reduces the

  6. NAC Transcription Factor SPEEDY HYPONASTIC GROWTH Regulates Flooding-Induced Leaf Movement in Arabidopsis[W

    PubMed Central

    Rauf, Mamoona; Arif, Muhammad; Fisahn, Joachim; Xue, Gang-Ping; Balazadeh, Salma; Mueller-Roeber, Bernd

    2013-01-01

    In rosette plants, root flooding (waterlogging) triggers rapid upward (hyponastic) leaf movement representing an important architectural stress response that critically determines plant performance in natural habitats. The directional growth is based on localized longitudinal cell expansion at the lower (abaxial) side of the leaf petiole and involves the volatile phytohormone ethylene (ET). We report the existence of a transcriptional core unit underlying directional petiole growth in Arabidopsis thaliana, governed by the NAC transcription factor SPEEDY HYPONASTIC GROWTH (SHYG). Overexpression of SHYG in transgenic Arabidopsis thaliana enhances waterlogging-triggered hyponastic leaf movement and cell expansion in abaxial cells of the basal petiole region, while both responses are largely diminished in shyg knockout mutants. Expression of several EXPANSIN and XYLOGLUCAN ENDOTRANSGLYCOSYLASE/HYDROLASE genes encoding cell wall–loosening proteins was enhanced in SHYG overexpressors but lowered in shyg. We identified ACC OXIDASE5 (ACO5), encoding a key enzyme of ET biosynthesis, as a direct transcriptional output gene of SHYG and found a significantly reduced leaf movement in response to root flooding in aco5 T-DNA insertion mutants. Expression of SHYG in shoot tissue is triggered by root flooding and treatment with ET, constituting an intrinsic ET-SHYG-ACO5 activator loop for rapid petiole cell expansion upon waterlogging. PMID:24363315

  7. A genetic link between epigenetic repressor AS1-AS2 and a putative small subunit processome in leaf polarity establishment of Arabidopsis.

    PubMed

    Matsumura, Yoko; Ohbayashi, Iwai; Takahashi, Hiro; Kojima, Shoko; Ishibashi, Nanako; Keta, Sumie; Nakagawa, Ayami; Hayashi, Rika; Saéz-Vásquez, Julio; Echeverria, Manuel; Sugiyama, Munetaka; Nakamura, Kenzo; Machida, Chiyoko; Machida, Yasunori

    2016-01-01

    Although the DEAD-box RNA helicase family is ubiquitous in eukaryotes, its developmental role remains unelucidated. Here, we report that cooperative action between the Arabidopsis nucleolar protein RH10, an ortholog of human DEAD-box RNA helicase DDX47, and the epigenetic repressor complex of ASYMMETRIC-LEAVES1 (AS1) and AS2 (AS1-AS2) is critical to repress abaxial (ventral) genes ETT/ARF3 and ARF4, which leads to adaxial (dorsal) development in leaf primordia at shoot apices. Double mutations of rh10-1 and as2 (or as1) synergistically up-regulated the abaxial genes, which generated abaxialized filamentous leaves with loss of the adaxial domain. DDX47 is part of the small subunit processome (SSUP) that mediates rRNA biogenesis. In rh10-1 we found various defects in SSUP-related events, such as: accumulation of 35S/33S rRNA precursors; reduction in the 18S/25S ratio; and nucleolar hypertrophy. Double mutants of as2 with mutations of genes that encode other candidate SSUP-related components such as nucleolin and putative rRNA methyltransferase exhibited similar synergistic defects caused by up-regulation of ETT/ARF3 and ARF4 These results suggest a tight link between putative SSUP and AS1-AS2 in repression of the abaxial-determining genes for cell fate decisions for adaxial development. PMID:27334696

  8. A genetic link between epigenetic repressor AS1-AS2 and a putative small subunit processome in leaf polarity establishment of Arabidopsis

    PubMed Central

    Matsumura, Yoko; Ohbayashi, Iwai; Takahashi, Hiro; Kojima, Shoko; Ishibashi, Nanako; Keta, Sumie; Nakagawa, Ayami; Hayashi, Rika; Saéz-Vásquez, Julio; Echeverria, Manuel; Sugiyama, Munetaka; Nakamura, Kenzo; Machida, Chiyoko

    2016-01-01

    ABSTRACT Although the DEAD-box RNA helicase family is ubiquitous in eukaryotes, its developmental role remains unelucidated. Here, we report that cooperative action between the Arabidopsis nucleolar protein RH10, an ortholog of human DEAD-box RNA helicase DDX47, and the epigenetic repressor complex of ASYMMETRIC-LEAVES1 (AS1) and AS2 (AS1-AS2) is critical to repress abaxial (ventral) genes ETT/ARF3 and ARF4, which leads to adaxial (dorsal) development in leaf primordia at shoot apices. Double mutations of rh10-1 and as2 (or as1) synergistically up-regulated the abaxial genes, which generated abaxialized filamentous leaves with loss of the adaxial domain. DDX47 is part of the small subunit processome (SSUP) that mediates rRNA biogenesis. In rh10-1 we found various defects in SSUP-related events, such as: accumulation of 35S/33S rRNA precursors; reduction in the 18S/25S ratio; and nucleolar hypertrophy. Double mutants of as2 with mutations of genes that encode other candidate SSUP-related components such as nucleolin and putative rRNA methyltransferase exhibited similar synergistic defects caused by up-regulation of ETT/ARF3 and ARF4. These results suggest a tight link between putative SSUP and AS1-AS2 in repression of the abaxial-determining genes for cell fate decisions for adaxial development. PMID:27334696

  9. Plant density and leaf area index effects on the distribution of light transmittance to the soil surface in maize

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Light is necessary for plants to grow and produce harvestable yield. The architecture of row crops results in variable light interception by the plants and variable energy transmittance to the soil according to leaf density, the orientation of the crop rows, and direction of sunlight. Better utili...

  10. Assimilation of Leaf Area Index and Soil Wetness Index into the ISBA-A-gs land surface model over France

    NASA Astrophysics Data System (ADS)

    Barbu, A. L.; Calvet, J.-C.; Lafont, S.

    2012-04-01

    The development of a Land Data Assimilation System (LDAS) dedicated to carbon and water cycles is considered as a key aspect for monitoring activities of terrestrial carbon fluxes. It allows the assimilation of biophysical products in order to reduce the bias between the model simulations and the observations and have a positive impact on carbon and water fluxes. This work shows the benefits of data assimilation of Earth observations for the monitoring of vegetation status and carbon fluxes, in the framework of the GEOLAND2 project, co-funded by the European Commission within the GMES initiative in FP7. In this study, the SURFEX modelling platform developed at Meteo-France is used for describing the continental vegetation state, surface fluxes and soil moisture. It consists of the land surface model ISBA-A-gs that simulates photosynthesis and plant growth. The vegetation biomass and Leaf Area Index (LAI) evolve dynamically in response to weather and climate conditions. The ECOCLIMAP database provides detailed information about the land cover at a resolution of 1 km. Over the France domain, the most present ecosystem types are grasslands (32%), C3 crop lands (24%), deciduous forest (20%), bare soil (11%), and C4 crop lands (8%).The model also includes a representation of the soil moisture stress with two different types of drought responses for herbaceous vegetation and forests. A version of the Extended Kalman Filter (EKF) scheme is developed for the joint assimilation of satellite-derived surface soil moisture from ASCAT-25 km product, namely Soil Wetness Index (SWI-01) developed by TU-Wien, and remote sensing LAI product provided by GEOLAND2. The GEOLAND2 LAI product is derived from CYCLOPES V3.1 and MODIS collection 5 data. It is more consistent with an effective LAI for low LAI and close to the actual LAI for high values. The assimilation experiment was conducted across France at a spatial resolution of 8 km. The study period ranges from July 2007 to December

  11. Variations in the dorso-ventral organization of leaf structure and Kranz anatomy coordinate the control of photosynthesis and associated signalling at the whole leaf level in monocotyledonous species.

    PubMed

    Soares-Cordeiro, Ana Sofia; Driscoll, Simon P; Pellny, Till K; Olmos, Enrique; Arrabaça, Maria Celeste; Foyer, Christine H

    2009-12-01

    Photosynthesis and associated signalling are influenced by the dorso-ventral properties of leaves. The degree of adaxial/abaxial symmetry in stomatal numbers, photosynthetic regulation with respect to light orientation and the total section areas of the bundle sheath (BS) cells and the surrounding mesophyll (M) cells on the adaxial and abaxial sides of the vascular bundles were compared in two C(4)[Zea mays (maize) and Paspalum dilatatum] and one C(3)[Triticum turgidum (Durum wheat)] monocotyledonous species. The C(3) leaves had a higher degree of dorso-ventral symmetry than the C(4) leaves. Photosynthetic regulation was the same on each side of the wheat leaves, as were stomatal numbers and the section area of the BS relative to that of the M cells (BS/M section area ratio). In contrast, photosynthetic regulation in maize and P. dilatatum leaves showed a marked surface-specific response to light orientation. Compared to the adaxial sides of the C(4) monocotyledonous leaves, the abaxial surfaces had more stomata and the BS/M section area ratio was significantly higher. Differences in dorso-ventral structure, particularly in Kranz anatomy, serve not only to maximize photosynthetic capacity with respect light orientation in C(4) monocotyledonous leaves but also allow adaxial and abaxial-specific signalling from the respective M cells. PMID:19712063

  12. Effective use of high CO₂ efflux at the soil surface in a tropical understory plant.

    PubMed

    Ishida, Atsushi; Nakano, Takashi; Adachi, Minaco; Yoshimura, Kenichi; Osada, Noriyuki; Ladpala, Phanumard; Diloksumpun, Sapit; Puangchit, Ladawan; Yoshimura, Jin

    2015-01-01

    Many terrestrial plants are C3 plants that evolved in the Mesozoic Era when atmospheric CO2 concentrations ([CO2]) were high. Given current conditions, C3 plants can no longer benefit from high ambient [CO2]. Kaempferia marginata Carey is a unique understory ginger plant in the tropical dry forests of Thailand. The plant has two large flat leaves that spread on the soil surface. We found a large difference in [CO2] between the partly closed space between the soil surface and the leaves (638 µmol mol(-1)) and the atmosphere at 20 cm above ground level (412 µmol mol(-1)). This finding indicates that the plants capture CO2 efflux from the soil. Almost all of the stomata are located on the abaxial leaf surface. When ambient air [CO2] was experimentally increased from 400 to 600 μmol mol(-1), net photosynthetic rates increased by 45 to 48% under near light-saturated conditions. No significant increase was observed under low light conditions. These data demonstrate that the unique leaf structure enhances carbon gain by trapping soil CO2 efflux at stomatal sites under relatively high light conditions, suggesting that ambient air [CO2] can serve as an important selective agent for terrestrial C3 plants. PMID:25758763

  13. Effective use of high CO2 efflux at the soil surface in a tropical understory plant

    PubMed Central

    Ishida, Atsushi; Nakano, Takashi; Adachi, Minaco; Yoshimura, Kenichi; Osada, Noriyuki; Ladpala, Phanumard; Diloksumpun, Sapit; Puangchit, Ladawan; Yoshimura, Jin

    2015-01-01

    Many terrestrial plants are C3 plants that evolved in the Mesozoic Era when atmospheric CO2 concentrations ([CO2]) were high. Given current conditions, C3 plants can no longer benefit from high ambient [CO2]. Kaempferia marginata Carey is a unique understory ginger plant in the tropical dry forests of Thailand. The plant has two large flat leaves that spread on the soil surface. We found a large difference in [CO2] between the partly closed space between the soil surface and the leaves (638 µmol mol−1) and the atmosphere at 20 cm above ground level (412 µmol mol−1). This finding indicates that the plants capture CO2 efflux from the soil. Almost all of the stomata are located on the abaxial leaf surface. When ambient air [CO2] was experimentally increased from 400 to 600 μmol mol−1, net photosynthetic rates increased by 45 to 48% under near light-saturated conditions. No significant increase was observed under low light conditions. These data demonstrate that the unique leaf structure enhances carbon gain by trapping soil CO2 efflux at stomatal sites under relatively high light conditions, suggesting that ambient air [CO2] can serve as an important selective agent for terrestrial C3 plants. PMID:25758763

  14. Effects of leaf area index on the coupling between water table, land surface energy fluxes, and planetary boundary layer at the regional scale

    NASA Astrophysics Data System (ADS)

    Lu, Y.; Rihani, J.; Langensiepen, M.; Simmer, C.

    2013-12-01

    Vegetation plays an important role in the exchange of moisture and energy at the land surface. Previous studies indicate that vegetation increases the complexity of the feedbacks between the atmosphere and subsurface through processes such as interception, root water uptake, leaf surface evaporation, and transpiration. Vegetation cover can affect not only the interaction between water table depth and energy fluxes, but also the development of the planetary boundary layer. Leaf Area Index (LAI) is shown to be a major factor influencing these interactions. In this work, we investigate the sensitivity of water table, surface energy fluxes, and atmospheric boundary layer interactions to LAI as a model input. We particularly focus on the role LAI plays on the location and extent of transition zones of strongest coupling and how this role changes over seasonal timescales for a real catchment. The Terrestrial System Modelling Platform (TerrSysMP), developed within the Transregional Collaborative Research Centre 32 (TR32), is used in this study. TerrSysMP consists of the variably saturated groundwater model ParFlow, the land surface model Community Land Model (CLM), and the regional climate and weather forecast model COSMO (COnsortium for Small-scale Modeling). The sensitivity analysis is performed over a range of LAI values for different vegetation types as extracted from the Moderate Resolution Imaging Spectroradiometer (MODIS) dataset for the Rur catchment in Germany. In the first part of this work, effects of vegetation structure on land surface energy fluxes and their connection to water table dynamics are studied using the stand-alone CLM and the coupled subsurface-surface components of TerrSysMP (ParFlow-CLM), respectively. The interconnection between LAI and transition zones of strongest coupling are investigated and analyzed through a subsequent set of subsurface-surface-atmosphere coupled simulations implementing the full TerrSysMP model system.

  15. Functional Analysis and RNA Sequencing Indicate the Regulatory Role of Argonaute1 in Tomato Compound Leaf Development.

    PubMed

    Wang, Tian; Li, Rui; Wen, Liwei; Fu, Daqi; Zhu, Benzhong; Luo, Yunbo; Zhu, Hongliang

    2015-01-01

    Regardless of whether a leaf is simple or compound, the mechanism underlying its development will give rise to a full comprehension of plant morphogenesis. The role of Argonaute1 (AGO1) in the development of simple leaves has been established, but its role in the development of compound leaves remains to be characterized. In this paper, a virus-induced gene silencing (VIGS) strategy was used to dramatically down-regulate the expression of AGO1 ortholog in tomatoes, a model plant for research into compound leaves. AGO1-silenced tomato compound leaves exhibited morphological defects of leaf adaxial-abaxial and trichome development. Analysis of global gene expression profiles indicated that the silencing of AGO1 in tomato compound leaf caused significant changes in the expression of several critical genes, including Auxin Response Factor 4 (ARF4) and Non-expressor of PR5 (NPR5), which were involved in adaxial-abaxial formation and IAA15 that was found to contribute to growth of trichomes as well as Gibberellic Acid Insensitive (GAI) which participated in hormone regulation. Collectively, these results shed light on the complicated mechanism by which AGO1 regulates compound leaf development. PMID:26479258

  16. Investigation of the influence of liquid water films on O3 and PAN deposition on plant leaf surfaces treated with organic / inorganic compounds

    NASA Astrophysics Data System (ADS)

    Sun, Shang; Moravek, Alexander; von der Heyden, Lisa; Held, Andreas; Kesselmeier, Jürgen; Sörgel, Matthias

    2016-04-01

    Liquid water films on environmental surfaces play an important role in various fields of interest (Burkhardt and Eiden, 1994). For example, the deposition of water soluble trace gases could be increased by surface moisture. Chameides and Stelson (1992) found out that the dissolution of trace gases in airborne particulate matter increases with rising water/solid ratio of the particles. Further, Flechard et al. (1999) concluded that deliquescent salt particles represent a potential sink for trace gases, depending on their chemical property. The formation of surface water films and its influence on the gas deposition was proposed by many previous studies (Fuentes and Gillespie, 1992, Burkhardt and Eiden, 1994, van Hove et al., 1989, Burkhardt et al., 1999, Flechard et al., 1999). In this study we investigate the influence of leaf surface water films on the deposition of O3 and PAN under controlled laboratory conditions. A twin cuvette system described in Sun et al. (2015) was used to control the environmental parameters such as light, temperature, trace gas mixing ratio and humidity. Furthermore, the leaf surface was treated with various organic and inorganic solutions to investigate the influence of deposited compounds on the electrical surface conductance of the leaves and the surface deposition of O3 and PAN at various relative humidities. The result shows that RHcrit, where the electrical surface conductance (G) increases exponentially, was 40 % during the light period and 50 % during the dark period. Furthermore, we observed that the formation of the leaf surface liquid film was depended on the deposited compounds on the leaf cuticles. For the O3 deposition on plants (Quercus ilex) a clear enhancement at rising environmental air humidity under light and dark condition was found. The increase during light conditions can be related partly to increasing stomatal conductance with higher RH. From the non-stomatal deposition measured in dark experiments, we could

  17. Tree branch angle: maximizing effective leaf area.

    PubMed

    Honda, H; Fisher, J B

    1978-02-24

    In a computer simulation of branching pattern and leaf cluster in Terminalia catappa, right and left branch angles were varied, and the effective leaf surface areas were calculated. Theoretical branch angles that result in maximum effective leaf area are close to the values observed in nature. PMID:17757590

  18. Molecular genetics of growth and development in Populus (Salicaceae). V. Mapping quantitative trait loci affecting leaf variation

    SciTech Connect

    Wu, R.; Bradshaw, H.D. Jr.; Stettler, R.F.

    1997-02-01

    The genetic variation of leaf morphology and development was studied in the 2-yr-old replicated plantation of an interspecific hybrid pedigree of Populus trichocarpa T. & G. and P. deltoides Marsh. via both molecular and quantitative genetic methods. Leaf traits chosen showed pronounced differences between the original parents, including leaf size, shape, orientation, color, structure, petiole size, and petiole cross section. In the F{sub 2} generation, leaf traits were all significantly different among genotypes, but with significant effects due to genotype X crown-position interaction. Variation in leaf pigmentation, petiole length, and petiole length proportion appeared to be under the control of few quantitative trait loci (QTLs). More QTLs were associated with single leaf area, leaf shape, lamina angle, abaxial color, and petiole flatness, and in these traits the number of QTLs varied among crown positions. In general the estimates of QTL numbers from Wright`s biometric method were close to those derived from molecular markers. For those traits with few underlying QTLs, a single marker interval could explain from 30-60% of the observed phenotypic variance. For multigenic traits, certain markers contributed more substantially to the observed variation than others. Genetic cluster analysis showed developmentally related traits to be more strongly associated with each other than with unrelated traits. This finding was also supported by the QTL mapping. For example, the same chromosomal segment of linkage group L seemed to account for 20% of the phenotypic variation of all dimension-related traits, leaf size, petiole length, and midrib angle. In both traits, the P. deltoides alleles had positive effects and were dominant to the P. trichocarpa alleles. Similar relationships were also found for lamina angle, abaxial greenness, and petiole flatness. 72 refs., 3 figs., 2 tabs.

  19. Leaf gas exchange and water status responses of a native and non-native grass to precipitation across contrasting soil surfaces in the Sonoran Desert.

    PubMed

    Ignace, Danielle D; Huxman, Travis E; Weltzin, Jake F; Williams, David G

    2007-06-01

    Arid and semi-arid ecosystems of the southwestern US are undergoing changes in vegetation composition and are predicted to experience shifts in climate. To understand implications of these current and predicted changes, we conducted a precipitation manipulation experiment on the Santa Rita Experimental Range in southeastern Arizona. The objectives of our study were to determine how soil surface and seasonal timing of rainfall events mediate the dynamics of leaf-level photosynthesis and plant water status of a native and non-native grass species in response to precipitation pulse events. We followed a simulated precipitation event (pulse) that occurred prior to the onset of the North American monsoon (in June) and at the peak of the monsoon (in August) for 2002 and 2003. We measured responses of pre-dawn water potential, photosynthetic rate, and stomatal conductance of native (Heteropogon contortus) and non-native (Eragrostis lehmanniana) C(4) bunchgrasses on sandy and clay-rich soil surfaces. Soil surface did not always amplify differences in plant response to a pulse event. A June pulse event lead to an increase in plant water status and photosynthesis. Whereas the August pulse did not lead to an increase in plant water status and photosynthesis, due to favorable soil moisture conditions facilitating high plant performance during this period. E. lehmanniana did not demonstrate heightened photosynthetic performance over the native species in response to pulses across both soil surfaces. Overall accumulated leaf-level CO(2) response to a pulse event was dependent on antecedent soil moisture during the August pulse event, but not during the June pulse event. This work highlights the need to understand how desert species respond to pulse events across contrasting soil surfaces in water-limited systems that are predicted to experience changes in climate. PMID:17333286

  20. Acetylation of cell wall is required for structural integrity of the leaf surface and exerts a global impact on plant stress responses

    PubMed Central

    Nafisi, Majse; Stranne, Maria; Fimognari, Lorenzo; Atwell, Susanna; Martens, Helle J.; Pedas, Pai R.; Hansen, Sara F.; Nawrath, Christiane; Scheller, Henrik V.; Kliebenstein, Daniel J.; Sakuragi, Yumiko

    2015-01-01

    The epidermis on leaves protects plants from pathogen invasion and provides a waterproof barrier. It consists of a layer of cells that is surrounded by thick cell walls, which are partially impregnated by highly hydrophobic cuticular components. We show that the Arabidopsis T-DNA insertion mutants of REDUCED WALL ACETYLATION 2 (rwa2), previously identified as having reduced O-acetylation of both pectins and hemicelluloses, exhibit pleiotrophic phenotype on the leaf surface. The cuticle layer appeared diffused and was significantly thicker and underneath cell wall layer was interspersed with electron-dense deposits. A large number of trichomes were collapsed and surface permeability of the leaves was enhanced in rwa2 as compared to the wild type. A massive reprogramming of the transcriptome was observed in rwa2 as compared to the wild type, including a coordinated up-regulation of genes involved in responses to abiotic stress, particularly detoxification of reactive oxygen species and defense against microbial pathogens (e.g., lipid transfer proteins, peroxidases). In accordance, peroxidase activities were found to be elevated in rwa2 as compared to the wild type. These results indicate that cell wall acetylation is essential for maintaining the structural integrity of leaf epidermis, and that reduction of cell wall acetylation leads to global stress responses in Arabidopsis. PMID:26257757

  1. Acetylation of cell wall is required for structural integrity of the leaf surface and exerts a global impact on plant stress responses

    SciTech Connect

    Nafisi, Majse; Stranne, Maria; Fimognari, Lorenzo; Atwell, Susanna; Martens, Helle J.; Pedas, Pai R.; Hansen, Sara F.; Nawrath, Christiane; Scheller, Henrik V.; Kliebenstein, Daniel J.; Sakuragi, Yumiko

    2015-07-22

    Here we report that the epidermis on leaves protects plants from pathogen invasion and provides a waterproof barrier. It consists of a layer of cells that is surrounded by thick cell walls, which are partially impregnated by highly hydrophobic cuticular components. We show that the Arabidopsis T-DNA insertion mutants of REDUCED WALL ACETYLATION 2 (rwa2), previously identified as having reduced O-acetylation of both pectins and hemicelluloses, exhibit pleiotrophic phenotype on the leaf surface. The cuticle layer appeared diffused and was significantly thicker and underneath cell wall layer was interspersed with electron-dense deposits. A large number of trichomes were collapsed and surface permeability of the leaves was enhanced in rwa2 as compared to the wild type. A massive reprogramming of the transcriptome was observed in rwa2 as compared to the wild type, including a coordinated up-regulation of genes involved in responses to abiotic stress, particularly detoxification of reactive oxygen species and defense against microbial pathogens (e.g., lipid transfer proteins, peroxidases). In accordance, peroxidase activities were found to be elevated in rwa2 as compared to the wild type. These results indicate that cell wall acetylation is essential for maintaining the structural integrity of leaf epidermis, and that reduction of cell wall acetylation leads to global stress responses in Arabidopsis.

  2. Acetylation of cell wall is required for structural integrity of the leaf surface and exerts a global impact on plant stress responses

    DOE PAGESBeta

    Nafisi, Majse; Stranne, Maria; Fimognari, Lorenzo; Atwell, Susanna; Martens, Helle J.; Pedas, Pai R.; Hansen, Sara F.; Nawrath, Christiane; Scheller, Henrik V.; Kliebenstein, Daniel J.; et al

    2015-07-22

    Here we report that the epidermis on leaves protects plants from pathogen invasion and provides a waterproof barrier. It consists of a layer of cells that is surrounded by thick cell walls, which are partially impregnated by highly hydrophobic cuticular components. We show that the Arabidopsis T-DNA insertion mutants of REDUCED WALL ACETYLATION 2 (rwa2), previously identified as having reduced O-acetylation of both pectins and hemicelluloses, exhibit pleiotrophic phenotype on the leaf surface. The cuticle layer appeared diffused and was significantly thicker and underneath cell wall layer was interspersed with electron-dense deposits. A large number of trichomes were collapsed andmore » surface permeability of the leaves was enhanced in rwa2 as compared to the wild type. A massive reprogramming of the transcriptome was observed in rwa2 as compared to the wild type, including a coordinated up-regulation of genes involved in responses to abiotic stress, particularly detoxification of reactive oxygen species and defense against microbial pathogens (e.g., lipid transfer proteins, peroxidases). In accordance, peroxidase activities were found to be elevated in rwa2 as compared to the wild type. These results indicate that cell wall acetylation is essential for maintaining the structural integrity of leaf epidermis, and that reduction of cell wall acetylation leads to global stress responses in Arabidopsis.« less

  3. Acetylation of cell wall is required for structural integrity of the leaf surface and exerts a global impact on plant stress responses.

    PubMed

    Nafisi, Majse; Stranne, Maria; Fimognari, Lorenzo; Atwell, Susanna; Martens, Helle J; Pedas, Pai R; Hansen, Sara F; Nawrath, Christiane; Scheller, Henrik V; Kliebenstein, Daniel J; Sakuragi, Yumiko

    2015-01-01

    The epidermis on leaves protects plants from pathogen invasion and provides a waterproof barrier. It consists of a layer of cells that is surrounded by thick cell walls, which are partially impregnated by highly hydrophobic cuticular components. We show that the Arabidopsis T-DNA insertion mutants of REDUCED WALL ACETYLATION 2 (rwa2), previously identified as having reduced O-acetylation of both pectins and hemicelluloses, exhibit pleiotrophic phenotype on the leaf surface. The cuticle layer appeared diffused and was significantly thicker and underneath cell wall layer was interspersed with electron-dense deposits. A large number of trichomes were collapsed and surface permeability of the leaves was enhanced in rwa2 as compared to the wild type. A massive reprogramming of the transcriptome was observed in rwa2 as compared to the wild type, including a coordinated up-regulation of genes involved in responses to abiotic stress, particularly detoxification of reactive oxygen species and defense against microbial pathogens (e.g., lipid transfer proteins, peroxidases). In accordance, peroxidase activities were found to be elevated in rwa2 as compared to the wild type. These results indicate that cell wall acetylation is essential for maintaining the structural integrity of leaf epidermis, and that reduction of cell wall acetylation leads to global stress responses in Arabidopsis. PMID:26257757

  4. Leaf Development

    PubMed Central

    2013-01-01

    Leaves are the most important organs for plants. Without leaves, plants cannot capture light energy or synthesize organic compounds via photosynthesis. Without leaves, plants would be unable perceive diverse environmental conditions, particularly those relating to light quality/quantity. Without leaves, plants would not be able to flower because all floral organs are modified leaves. Arabidopsis thaliana is a good model system for analyzing mechanisms of eudicotyledonous, simple-leaf development. The first section of this review provides a brief history of studies on development in Arabidopsis leaves. This history largely coincides with a general history of advancement in understanding of the genetic mechanisms operating during simple-leaf development in angiosperms. In the second section, I outline events in Arabidopsis leaf development, with emphasis on genetic controls. Current knowledge of six important components in these developmental events is summarized in detail, followed by concluding remarks and perspectives. PMID:23864837

  5. Assimilation of Soil Wetness Index and Leaf Area Index into the ISBA-A-gs land surface model: grassland case study

    NASA Astrophysics Data System (ADS)

    Barbu, A. L.; Calvet, J.-C.; Mahfouf, J.-F.; Albergel, C.; Lafont, S.

    2011-02-01

    The performance of the joint assimilation in a land surface model of a Soil Wetness Index (SWI) product provided by an exponential filter together with Leaf Area Index (LAI) is investigated. The data assimilation is evaluated with different setups using the SURFEX modeling platform, for a period of seven years (2001-2007), at the SMOSREX grassland site in southwestern France. The results obtained with a Simplified Extended Kalman Filter demonstrate the effectiveness of a joint data assimilation scheme when both SWI and Leaf Area Index are merged into the ISBA-A-gs land surface model. The assimilation of a retrieved Soil Wetness Index product presents several challenges that are investigated in this study. A significant improvement of around 13% of the root-zone soil water content is obtained by assimilating dimensionless root-zone SWI data. For comparison, the assimilation of in situ surface soil moisture is considered as well. A lower impact on the root zone is noticed. Under specific conditions, the transfer of the information from the surface to the root zone was found not accurate. Also, our results indicate that the assimilation of in situ LAI data may correct a number of deficiencies in the model, such as low LAI values in the senescence phase by using a seasonal-dependent error definition for background and observations. In order to verify the specification of the errors for SWI and LAI products, a posteriori diagnostics are employed. This approach highlights the importance of the assimilation design on the quality of the analysis. The impact of data assimilation scheme on CO2 fluxes is also quantified by using measurements of net CO2 fluxes gathered at the SMOSREX site from 2005 to 2007. An improvement of about 5% in terms of rms error is obtained.

  6. Assimilation of Soil Wetness Index and Leaf Area Index into the ISBA-A-gs land surface model: grassland case study

    NASA Astrophysics Data System (ADS)

    Barbu, A. L.; Calvet, J.-C.; Mahfouf, J.-F.; Albergel, C.; Lafont, S.

    2011-07-01

    The performance of the joint assimilation in a land surface model of a Soil Wetness Index (SWI) product provided by an exponential filter together with Leaf Area Index (LAI) is investigated. The data assimilation is evaluated with different setups using the SURFEX modeling platform, for a period of seven years (2001-2007), at the SMOSREX grassland site in southwestern France. The results obtained with a Simplified Extended Kalman Filter demonstrate the effectiveness of a joint data assimilation scheme when both SWI and Leaf Area Index are merged into the ISBA-A-gs land surface model. The assimilation of a retrieved Soil Wetness Index product presents several challenges that are investigated in this study. A significant improvement of around 13 % of the root-zone soil water content is obtained by assimilating dimensionless root-zone SWI data. For comparison, the assimilation of in situ surface soil moisture is considered as well. A lower impact on the root zone is noticed. Under specific conditions, the transfer of the information from the surface to the root zone was found not accurate. Also, our results indicate that the assimilation of in situ LAI data may correct a number of deficiencies in the model, such as low LAI values in the senescence phase by using a seasonal-dependent error definition for background and observations. In order to verify the specification of the errors for SWI and LAI products, a posteriori diagnostics are employed. This approach highlights the importance of the assimilation design on the quality of the analysis. The impact of data assimilation scheme on CO2 fluxes is also quantified by using measurements of net CO2 fluxes gathered at the SMOSREX site from 2005 to 2007. An improvement of about 5 % in terms of rms error is obtained.

  7. Land surface phenology in eastern United States watersheds: relationship between remote sensing metrics, stream chemistry, snow cover, and leaf and bird phenology

    NASA Astrophysics Data System (ADS)

    White, M. A.; Baker, M.; Weller, D.; Jordan, T.

    2006-12-01

    Remote sensing of terrestrial land surfaces has long promised an unprecedented ability to regularly and consistently monitor patterns of vegetation phenology, which in turn implied an ability to develop prognostic phenology models and/or directly to force seasonality within climate models. Within the last five years, though, research has shown that land surface phenology, which is the integral signal of atmospheric, snow, soil, cloud, and vegetation, can be dramatically different than vegetation phenology alone. Consequently, there is a strong need to understand the usually unique relationship between remotely sensed land surface phenology and a continuum of ground-based processes. Here, using a network of watersheds in the Coastal Plain and Piedmont regions of the Chesapeake Bay, we conducted a four-part analysis for the 1997 to 1999 period. First, using a recently developed land surface phenology technique designed to represent a continuum, rather than a specific event (i.e. the start of the growing season), we calculated the daily percent above threshold (PAT), a metric of the percent of the watershed above a locally assigned greenness threshold. Second, we assembled a collection of measured leaf and hummingbird phenology and snow cover data. Third, we obtained weekly measurements of stream flow, total nitrogen (N), organic N, Kjeldahl N, ammonium, nitrate, total phosphorous, organic phosphorous, and phosphate. Fourth, as the stream chemistry data was collected irregularly across watersheds, we then calculated weekly average PAT and stream chemistry values. We found that for these watersheds, observed patterns of PAT increase were unrelated to snow cover and coincident with a continuum of ground-measured leaf phenology and hummingbird appearance. The spring increase in PAT also was consistently related to reductions in nitrate load, but not to other water chemistry measurement, suggesting an interaction between vegetative N demand and stream nitrate.

  8. The mycorrhiza fungus Piriformospora indica induces fast root-surface pH signaling and primes systemic alkalinization of the leaf apoplast upon powdery mildew infection.

    PubMed

    Felle, Hubert H; Waller, Frank; Molitor, Alexandra; Kogel, Karl-Heinz

    2009-09-01

    We analyze here, by noninvasive electrophysiology, local and systemic plant responses in the interaction of barley (Hordeum vulgare L.) with the root-colonizing basidiomycete Piriformospora indica. In the short term (seconds, minutes), a constant flow of P. indica chlamydospores along primary roots altered surface pH characteristics; whereas the root-hair zone transiently alkalized-a typical elicitor response-the elongation zone acidified, indicative of enhanced H(+) extrusion and plasma membrane H(+) ATPase stimulation. Eight to 10 min after treating roots with chlamydospores, the apoplastic pH of leaves began to acidify, which contrasts with observations of an alkalinization response to various stressors and microbe-associated molecular patterns (MAMPs). In the long term (days), plants with P. indica-colonized roots responded to inoculation with the leaf-pathogenic powdery mildew fungus Blumeria graminis f. sp. hordei with a leaf apoplastic pH increase of about 2, while the leaf apoplast of noncolonized barley responded to B. graminis f. sp. hordei merely with a pH increase of 0.8. The strong apoplastic pH response is reminiscent of B. graminis f. sp. hordei-triggered pH shifts in resistance gene-mediated resistant barley leaves or upon treatment with a chemical resistance inducer. In contrast, the MAMP N-acetylchito-octaose did not induce resistance to B. graminis f. sp. hordei and did not trigger the primed apoplastic pH shift. We speculate that the primed pH increase is indicative of and supports the potentiated systemic response to B. graminis f. sp. hordei-induced by P. indica in barley. PMID:19656052

  9. The endophytic symbiont Epichloë festucae establishes an epiphyllous net on the surface of Lolium perenne leaves by development of an expressorium, an appressorium-like leaf exit structure.

    PubMed

    Becker, Matthias; Becker, Yvonne; Green, Kimberly; Scott, Barry

    2016-07-01

    Epichloë festucae forms a mutualistic symbiotic association with Lolium perenne. This biotrophic fungus systemically colonizes the intercellular spaces of aerial tissues to form an endophytic hyphal network. E. festucae also grows as an epiphyte, but the mechanism for leaf surface colonization is not known. Here we identify an appressorium-like structure, which we call an expressorium that allows endophytic hyphae to penetrate the cuticle from the inside of the leaf to establish an epiphytic hyphal net on the surface of the leaf. We used a combination of scanning electron, transmission electron and confocal laser scanning microscopy to characterize this novel fungal structure and determine the composition of the hyphal cell wall using aniline blue and wheat germ agglutinin labelled with Alexafluor-488. Expressoria differentiate immediately below the cuticle in the leaf blade and leaf sheath intercalary cell division zones where the hyphae grow by tip growth. Differentiation of this structure requires components of both the NoxA and NoxB NADPH oxidase complexes. Major remodelling of the hyphal cell wall occurs following exit from the leaf. These results establish that the symbiotic association of E. festucae with L. perenne involves an interconnected hyphal network of both endophytic and epiphytic hyphae. PMID:26991322

  10. Using the Normalized Differential Wetness Index to Scale Leaf Area Index, Create Three-Dimensional Classification Maps, and Scale Seasonal Evapotranspiration Depletions in Canopies Along the Middle Rio Grande Riparian CorridorCorridor

    NASA Astrophysics Data System (ADS)

    McDonnell, D. E.; Cleverly, J. R.; Dahm, C. N.; Coonrod, J. A.

    2005-12-01

    Radiation per day (Rn). The best relationship results when stomatal side surface area is considered. Cladophylls have stomata on all sides while flat leaves have stomata on the abaxial side only. The correction multiplies LAI by .5 in flat leaf vegetation and 1 in T. chinensis vegetation. That means that transpiration rates are two times greater in T. chinensis sites compared with P. deltoides for the same leaf area. The resulting equations are put into a model to quantify ET for each available image and then for the entire growing season.

  11. “Breath figures” on leaf surfaces—formation and effects of microscopic leaf wetness

    PubMed Central

    Burkhardt, Juergen; Hunsche, Mauricio

    2013-01-01

    “Microscopic leaf wetness” means minute amounts of persistent liquid water on leaf surfaces which are invisible to the naked eye. The water is mainly maintained by transpired water vapor condensing onto the leaf surface and to attached leaf surface particles. With an estimated average thickness of less than 1 μm, microscopic leaf wetness is about two orders of magnitude thinner than morning dewfall. The most important physical processes which reduce the saturation vapor pressure and promote condensation are cuticular absorption and the deliquescence of hygroscopic leaf surface particles. Deliquescent salts form highly concentrated solutions. Depending on the type and concentration of the dissolved ions, the physicochemical properties of microscopic leaf wetness can be considerably different from those of pure water. Microscopic leaf wetness can form continuous thin layers on hydrophobic leaf surfaces and in specific cases can act similar to surfactants, enabling a strong potential influence on the foliar exchange of ions. Microscopic leaf wetness can also enhance the dissolution, the emission, and the reaction of specific atmospheric trace gases e.g., ammonia, SO2, or ozone, leading to a strong potential role for microscopic leaf wetness in plant/atmosphere interaction. Due to its difficult detection, there is little knowledge about the occurrence and the properties of microscopic leaf wetness. However, based on the existing evidence and on physicochemical reasoning it can be hypothesized that microscopic leaf wetness occurs on almost any plant worldwide and often permanently, and that it significantly influences the exchange processes of the leaf surface with its neighboring compartments, i.e., the plant interior and the atmosphere. The omission of microscopic water in general leaf wetness concepts has caused far-reaching, misleading conclusions in the past. PMID:24167510

  12. Bioinspired Surface for Low Drag, Self-Cleaning, and Antifouling: Shark Skin, Butterfly and Rice Leaf Effects

    NASA Astrophysics Data System (ADS)

    Bixler, Gregroy D.

    In this thesis, first presented is an overview of inorganic-fouling and biofouling which is generally undesirable for many medical, marine, and industrial applications. A survey of nature's flora and fauna are studied in order to discover new antifouling methods that could be mimicked for engineering applications. New antifouling methods will presumably incorporate a combination of physical and chemical controls. Presented are mechanisms and experimental results focusing on laminar and turbulent drag reducing shark skin inspired riblet surfaces. This includes new laser etched and riblet film samples for closed channel drag using water, oil, and air as well as in wind tunnel. Also presented are mechanisms and experimental results focusing on the newly discovered rice and butterfly wing effect surfaces. Morphology, drag, self-cleaning, contact angle, and contact angle hysteresis data are presented to understand the role of sample geometrical dimensions, wettability, viscosity, and velocity. Hierarchical liquid repellent coatings combining nano- and micro-sized features and particles are utilized to recreate or combine various effects. Such surfaces have been fabricated with photolithography, soft lithography, hot embossing, and coating techniques. Discussion is provided along with new conceptual models describing the role of surface structures related to low drag, self-cleaning, and antifouling properties. Modeling provides design guidance when developing novel low drag and self-cleaning surfaces for medical, marine, and industrial applications.

  13. Global estimation of evapotranspiration using a leaf area index-based surface energy and water balance model

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Studies of global hydrologic cycles, carbon cycles and climate change are greatly facilitated when global estimates of evapotranspiration (E) are available. We have developed an air-relative-humidity-based two-source (ARTS) E model that simulates the surface energy balance, soil water balance, and e...

  14. Captive bubble and sessile drop surface characterization of a submerged aquatic plant, Hydrilla verticillata

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The surface energy parameters of the invasive aquatic weed, Hydrilla verticillata, were determined using contact angle measurements using two different methods. The abaxial and adaxial surfaces of the leaves and stem were characterized for the weed while submerged in water using captive air and octa...

  15. Integrating ASCAT surface soil moisture and GEOV1 leaf area index into the SURFEX modelling platform: a land data assimilation application over France

    NASA Astrophysics Data System (ADS)

    Barbu, A. L.; Calvet, J.-C.; Mahfouf, J.-F.; Lafont, S.

    2013-07-01

    The land monitoring service of the European Copernicus programme has developed a set of satellite-based biogeophysical products, including surface soil moisture (SSM) and leaf area index (LAI). This study investigates the impact of joint assimilation of remotely sensed SSM derived from ASCAT backscatter data and the GEOV1 satellite-based LAI into the ISBA-A-gs land surface model within the SURFEX modelling platform of Meteo-France. The ASCAT data were bias corrected with respect to the model climatology by using a seasonal-based CDF (Cumulative Distribution Function) matching technique. A multivariate multi-scale land data assimilation system (LDAS) based on the Extended Kalman Filter (EKF) is used for monitoring the soil moisture, terrestrial vegetation, surface carbon and energy fluxes across the France domain at a spatial resolution of 8 km. Each model grid box is divided in a number of land covers, each having its own set of prognostic variables. The filter algorithm is designed to provide a distinct analysis for each land cover while using one observation per grid box. The updated values are aggregated by computing a weighted average. In this study, it is demonstrated that the assimilation scheme works effectively within the ISBA-A-gs model over a four-year period (2008-2011). The EKF is able to extract useful information from the data signal at the grid scale and to distribute the root-zone soil moisture and LAI increments among the mosaic structure of the model. The impact of the assimilation on the vegetation phenology and on the water and carbon fluxes varies from one season to another. The spring drought of 2011 is an interesting case study showing the potential of the assimilation to improve drought monitoring. A comparison between simulated and in situ soil moisture gathered at the twelve SMOSMANIA stations shows improved anomaly correlations for eight stations.

  16. Effect of herbivore damage on broad leaf motion in wind

    NASA Astrophysics Data System (ADS)

    Burnett, Nicholas; Kothari, Adit

    2015-11-01

    Terrestrial plants regularly experience wind that imposes aerodynamic forces on the plants' leaves. Passive leaf motion (e.g. fluttering) and reconfiguration (e.g. rolling into a cone shape) in wind can affect the drag on the leaf. In the study of passive leaf motion in wind, little attention has been given to the effect of herbivory. Herbivores may alter leaf motion in wind by making holes in the leaf. Also, a small herbivore (e.g. snail) on a leaf can act as a point mass, thereby affecting the leaf's motion in wind. Conversely, accelerations imposed on an herbivore sitting on a leaf by the moving leaf may serve as a defense by dislodging the herbivore. In the present study, we investigated how point masses (>1 g) and holes in leaves of the tuliptree affected passive leaf motion in turbulent winds of 1 and 5 m s-1. Leaf motion was unaffected by holes in the leaf surface (about 10% of leaf area), but an herbivore's mass significantly damped the accelerations of fluttering leaves. These results suggest that an herbivore's mass, but not the damage it inflicts, can affect leaf motion in the wind. Furthermore, the damping of leaf fluttering from an herbivore's mass may prevent passive leaf motions from being an effective herbivore defense.

  17. Exchange fluxes of NO2 and O3 at soil and leaf surfaces in an Amazonian rain forest

    NASA Astrophysics Data System (ADS)

    Gut, A.; Scheibe, M.; Rottenberger, S.; Rummel, U.; Welling, M.; Ammann, C.; Kirkman, G. A.; Kuhn, U.; Meixner, F. X.; Kesselmeier, J.; Lehmann, B. E.; Schmidt, W.; Müller, E.; Piedade, M. T. F.

    2002-10-01

    Trace gas exchange of NO2 and O3 at the soil surface of the primary rain forest in Reserva Biológica Jarú (Rondônia, Brazil) was investigated by chamber and gradient methods. The ground resistance to NO2 and O3 deposition to soil was quantified for dry and wet surface conditions using dynamic chambers and was found to be fairly constant at 340 ± 110 and 190 ± 70 s m-1, respectively. For clear-sky conditions, the thermal stratification of the air in the first meter from the forest floor was stable during daytime and unstable during nighttime. The aerodynamic resistance to NO2 and O3 deposition to the ground in the first meter above the forest floor was determined by measurements of 220Rn and CO2 concentration gradients and CO2 surface fluxes. The aerodynamic resistance of the 1-m layer above the ground was 1700 s m-1 during daytime and 600 s m-1 during nighttime. The deposition flux of O3 and NO2 was quantified for clear-sky conditions from the measured concentrations and the quantified resistances. For both trace gases, deposition to the soil was generally observed. The O3 deposition flux to the soil was only significantly different from zero during daytime. The maximum of -1.2 nmol m-2 s-1 was observed at about 1800 and the mean daytime flux was -0.5 nmol m-2 s-1. The mean NO2 deposition flux during daytime was -1.6 ng N m-2 s-1 and during nighttime -2.2 ng N m-2 s-1. The NOx budget at the soil surface yielded net emission day and night. The NO2 deposition flux was 74% of the soil NO emission flux during nighttime and 34% during daytime. The plant uptake of NO2 and O3 by the leaves of Laetia corymbulosa and Pouteria glomerata, two typical plant species for the Amazon rain forest, was investigated in a greenhouse in Oldenburg (Germany) using branch cuvettes. The uptake of O3 was found to be completely under stomatal control. The uptake of NO2 was also controlled by the stomatal resistance but an additional mesophyll resistance of the same order of magnitude as

  18. Detection of oligonucleotide hybridization at femtomolar level and sequence-specific gene analysis of the Arabidopsis thaliana leaf extract with an ultrasensitive surface plasmon resonance spectrometer

    PubMed Central

    Song, Fayi; Zhou, Feimeng; Wang, Jun; Tao, Nongjian; Lin, Jianqiao; Vellanoweth, Robert L.; Morquecho, Yvonne; Wheeler-Laidman, Janel

    2002-01-01

    A flow-injection (FI) device is combined, through the use of a low-volume (4 µl) flow cell, with an ultrasensitive surface plasmon resonance (SPR) spectrometer equipped with a bi-cell photodiode detector. The application of this novel FI–SPR device for sequence-specific ultratrace analysis of oligodeoxynucleotides (ODNs) and polydeoxynucleotides was demonstrated. Self-assembled monolayers of ODN probes are tethered onto Au films with a mercaptohexyl group at the 3′ ends. The FI–SPR provides a detection level (≤54 fM) 2–3 orders of magnitude lower than other SPR devices and compares well with several ultrasensitive detection methods for labeled DNA targets (e.g. fluorophore-tagged and radiolabeled DNA samples). The technique is also highly selective, since a 47mer ODN target with a single-base mismatch yielded a much smaller SPR signal, and a specific interaction was detected when the complementary target was present at 0.001% of the total DNA. The FI–SPR was extended to the measurement of two individual genes in a cDNA mixture transcribed from an Arabidopsis thaliana leaf mRNA pool. The greatly enhanced sensitivity not only obviates the necessity of DNA labeling, but also significantly reduces sample consumption, allowing direct quantification of low abundance mRNAs in cellular samples without amplification. PMID:12136120

  19. Leaf Level Chlorophyll Fluorescence Emission Spectra: Narrow Band versus Full 650-800 nm Retrievals

    NASA Astrophysics Data System (ADS)

    Middleton, E.; Zhang, Q.; Campbell, P. K.; Huemmrich, K. F.; Corp, L.; Cheng, Y.

    2012-12-01

    Recently, chlorophyll fluorescence (ChlF) retrievals in narrow spectral regions (< 1 nm, between 750-770 nm) of the near infrared (NIR) region of Earth's reflected radiation have been achieved from satellites, including the Japanese GOSAT and the European Space Agency's Sciamachy/Envisat. However, these retrievals sample the total full-spectrum ChlF and are made at non-optimal wavelengths since they are not located at the peak fluorescence emission features. We wish to estimate the total full-spectrum ChlF based on emissions obtained at selected wavelengths. For this, we drew upon leaf emission spectra measured on corn leaves obtained from a USDA experimental cornfield in MD (USA). These emission spectra were determined for the adaxial and abaxial (i.e., top and underside) surfaces of leaves measured throughout the 2008 and 2011 growing seasons (n>400) using a laboratory instrument (Fluorolog-3, Horiba Scientific, USA), recorded in either 1 nm or 5 nm increments with monochromatic excitation wavelengths of either 532 or 420 nm. The total ChlF signal was computed as the area under the continuous spectral emission curves, summing the emission intensities (counts per second) per waveband. The individual narrow (1 or 5 nm) waveband emission intensities were linearly related to full emission values, with variable success across the spectrum. Equations were developed to estimate total ChlF from these individual wavebands. Here, we report the results for the average adaxial/abaxial emissions. Very strong relationships were achieved for the relatively high fluorescence intensities at the red chlorophyll peak, centered at 685 nm (r2= 0.98, RMSE = 5.53 x 107 photons/s) and in the nearby O2-B atmospheric absorption feature centered at 688 nm (r2 = 0.94, RMSE = 4.04 x 107), as well as in the far-red peak centered at 740 nm (r2=0.94, RMSE = 5.98 x107). Very good retrieval success occurred for the O2-A atmospheric absorption feature on the declining NIR shoulder centered at 760

  20. Drag increase and drag reduction found in phytoplankton and bacterial cultures in laminar flow: Are cell surfaces and EPS producing rheological thickening and a Lotus-leaf Effect?

    NASA Astrophysics Data System (ADS)

    Jenkinson, Ian R.; Sun, Jun

    2014-03-01

    The laminar-flow viscosity of ocean and other natural waters consists of a Newtonian aqueous component contributed by water and salts, and a non-Newtonian one contributed mainly by exopolymeric polymers (EPS) derived largely from planktonic algae and bacteria. Phytoplankton and EPS form thin layers in stratified waters, often associated with density discontinuities. A recent model (Jenkinson and Sun, 2011. J. Plankton Res., 33, 373-383) investigated possible thalassorheological control of pycnocline thickness (PT) by EPS secreted by the harmful dinoflagellate Karenia mikimotoi. The model, based on published measurements of viscosity increase by this species, found that whether it can influence PT depends on the relationship between increased viscosity, deformation rates/stresses and length scale, which the present work has investigated. To do this, flow rate vs. hydrostatic pressure (and hence wall stress) was measured in cultures (relative to that in reference water) in capillaries of 5 radii 0.35-1.5 mm, close to oceanic-turbulence Kolmogorov length. We compared cultures of the potentially harmful algae, K. mikimotoi, Alexandrium catenella, Prorocentrum donghaiense, Skeletonema costatum, Phaeodactylum tricornutum and the bacterium Escherichia coli. Drag increase, ascribed to rheological thickening by EPS, occurred in the smallest capillaries, but drag reduction (DR) occurred in the largest ones. Since this occurred at Reynolds numbers Re too small for turbulence (or turbulent DR) to occur, this was laminar-flow DR. It may have been superhydrophobic DR (SDR), associated with the surfaces of the plankton and bacteria. SDR is associated with the self-cleaning Lotus-leaf Effect, in which water and dirt are repelled from surfaces bearing nm- to µm-sized irregularities coated with hydrophobic polymers. Because DR decreased measured viscosity and EPS thickening increased it, we could not validate the model. DR, however, represents hitherto unknown phenomenon in the

  1. Assimilation of Cyclopes Leaf Area Index into the ISBA-A-GS Land Surface Model over France

    NASA Astrophysics Data System (ADS)

    Barbu, Alina L.; Calvet, J.-C.; Lafont, S.

    2011-01-01

    In our study the SURFEX modeling platform is used in off-line mode. It contains the land surface model ISBA- A-gs that simulates photosynthesis and plant growth. A version of the Extended Kalman Filter scheme is used for the assimilation in situ and CYCLOPES LAI product de- rived from the SPOT4/VEGETATION sensor within the ISBA-A-gs model. The LAI data is incorporated into the model every 10 days to analyse its impact on vegetation biomass. The experiment is performed over France at a spatial resolution of 8 km. A model grid box is divided in a number of patches each having its own set of prognostic variables. The filter algorithm is designed to provide the analysis for each patches independently by using one observation per grid box. When needed, the updated values are aggregated by computing a weighted average. In this study we demonstrate that the assimilation scheme works effectively within the multi-patch version of our model. An important reduction of the LAI bias between the model and measurements is achieved.

  2. Leaf Histology--Two Modern Methods.

    ERIC Educational Resources Information Center

    Freeman, H. E.

    1984-01-01

    Two methods for examining leaf structure are presented; both methods involve use of "superglue." The first method uses the glue to form a thin, permanent, direct replica of a leaf surface on a microscope slide. The second method uses the glue to examine the three-dimensional structure of spongy mesophyll. (JN)

  3. Surface Structures Involved in Plant Stomata and Leaf Colonization by Shiga-Toxigenic Escherichia Coli O157:H7

    PubMed Central

    Saldaña, Zeus; Sánchez, Ethel; Xicohtencatl-Cortes, Juan; Puente, Jose Luis; Girón, Jorge A.

    2011-01-01

    Shiga-toxigenic Escherichia coli (STEC) O157:H7 uses a myriad of surface adhesive appendages including pili, flagella, and the type 3 secretion system (T3SS) to adhere to and inflict damage to the human gut mucosa. Consumption of contaminated ground beef, milk, juices, water, or leafy greens has been associated with outbreaks of diarrheal disease in humans due to STEC. The aim of this study was to investigate which of the known STEC O157:H7 adherence factors mediate colonization of baby spinach leaves and where the bacteria reside within tainted leaves. We found that STEC O157:H7 colonizes baby spinach leaves through the coordinated production of curli, the E. coli common pilus, hemorrhagic coli type 4 pilus, flagella, and T3SS. Electron microscopy analysis of tainted leaves revealed STEC bacteria in the internal cavity of the stomata, in intercellular spaces, and within vascular tissue (xylem and phloem), where the bacteria were protected from the bactericidal effect of gentamicin, sodium hypochlorite or ozonated water treatments. We confirmed that the T3S escN mutant showed a reduced number of bacteria within the stomata suggesting that T3S is required for the successful colonization of leaves. In agreement, non-pathogenic E. coli K-12 strain DH5α transformed with a plasmid carrying the locus of enterocyte effacement (LEE) pathogenicity island, harboring the T3SS and effector genes, internalized into stomata more efficiently than without the LEE. This study highlights a role for pili, flagella, and T3SS in the interaction of STEC with spinach leaves. Colonization of plant stomata and internal tissues may constitute a strategy by which STEC survives in a nutrient-rich microenvironment protected from external foes and may be a potential source for human infection. PMID:21887151

  4. Integrating ASCAT surface soil moisture and GEOV1 leaf area index into the SURFEX modelling platform: a land data assimilation application over France

    NASA Astrophysics Data System (ADS)

    Barbu, A. L.; Calvet, J.-C.; Mahfouf, J.-F.; Lafont, S.

    2014-01-01

    The land monitoring service of the European Copernicus programme has developed a set of satellite-based biogeophysical products, including surface soil moisture (SSM) and leaf area index (LAI). This study investigates the impact of joint assimilation of remotely sensed SSM derived from Advanced Scatterometer (ASCAT) backscatter data and the Copernicus Global Land GEOV1 satellite-based LAI product into the the vegetation growth version of the Interactions between Soil Biosphere Atmosphere (ISBA-A-gs) land surface model within the the externalised surface model (SURFEX) modelling platform of Météo-France. The ASCAT data were bias corrected with respect to the model climatology by using a seasonal-based CDF (Cumulative Distribution Function) matching technique. A multivariate multi-scale land data assimilation system (LDAS) based on the extended Kalman Filter (EKF) is used for monitoring the soil moisture, terrestrial vegetation, surface carbon and energy fluxes across the domain of France at a spatial resolution of 8 km. Each model grid box is divided into a number of land covers, each having its own set of prognostic variables. The filter algorithm is designed to provide a distinct analysis for each land cover while using one observation per grid box. The updated values are aggregated by computing a weighted average. In this study, it is demonstrated that the assimilation scheme works effectively within the ISBA-A-gs model over a four-year period (2008-2011). The EKF is able to extract useful information from the data signal at the grid scale and distribute the root-zone soil moisture and LAI increments throughout the mosaic structure of the model. The impact of the assimilation on the vegetation phenology and on the water and carbon fluxes varies from one season to another. The spring drought of 2011 is an interesting case study of the potential of the assimilation to improve drought monitoring. A comparison between simulated and in situ soil moisture gathered at

  5. Stomatal response and leaf injury of Pisum sativum L. with SO/sub 2/ and O/sub 3/ exposures. I. Influence of pollutant level and leaf maturity

    SciTech Connect

    Olszyk, D.M.; Tibbitts, T.W.

    1981-03-01

    Plants of Pisum sativum L. Alsweet were grown under a controlled environment and exposed to SO/sub 2/ and O/sub 3/ to determine whether changes in stomatal aperture during exposure were related to subsequent leaf injury. Stomata consistently closed with injurious levels of SO/sub 2/ and O/sub 3/. Measurements with diffusion porometers demonstrated approx. = 75 and 25% lower conductance with SO/sub 2/ and O/sub 3/ exposures, respectively, compared to the conductance of control plants. Stomata also showed a closing response with noninjurious levels of SO/sub 2/ but an opening response with noninjurious levels of O/sub 3/. Stomata closed to the same degree with combinations of SO/sub 2/ plus O/sub 3/ as with SO/sub 2/ alone. Stomata of expanding leaves closed more during pollutant exposures than stomata of expanded leaves. The abaxial and adaxial stomata both exhibited closure with SO/sub 2/ and combinations of SO/sub 2/ plus O/sub 3/, but abaxial stomata tended to close and adaxial stomata tended to open with exposure to O/sub 3/ alone. The changes in stomatal aperture were not closely correlated with the amount of leaf injury produced by different pollutant levels. Stomata closed, not only with exposure to pollutant levels that caused severe necrosis, but also with levels that caused only a trace of injury. There was no evidence of a reduced amount of closure or even stomatal opening with combinations of SO/sub 2/ and O/sub 3/ compared to plants exposed to the pollutants alone to explain the large amount of injury to plants exposed to pollutant combinations.

  6. Biophysical control of leaf temperature

    NASA Astrophysics Data System (ADS)

    Dong, N.; Prentice, I. C.; Wright, I. J.

    2014-12-01

    In principle sunlit leaves can maintain their temperatures within a narrower range than ambient temperatures. This is an important and long-known (but now overlooked) prediction of energy balance theory. Net radiation at leaf surface in steady state (which is reached rapidly) must be equal to the combination of sensible and latent heat exchanges with surrounding air, the former being proportional to leaf-to-air temperature difference (ΔT), the latter to the transpiration rate. We present field measurements of ΔT which confirm the existence of a 'crossover temperature' in the 25-30˚C range for species in a tropical savanna and a tropical rainforest environment. This finding is consistent with a simple representation of transpiration as a function of net radiation and temperature (Priestley-Taylor relationship) assuming an entrainment factor (ω) somewhat greater than the canonical value of 0.26. The fact that leaves in tropical forests are typically cooler than surrounding air, often already by solar noon, is consistent with a recently published comparison of MODIS day-time land-surface temperatures with air temperatures. Theory further predicts a strong dependence of leaf size (which is inversely related to leaf boundary-layer conductance, and therefore to absolute magnitude of ΔT) on moisture availability. Theoretically, leaf size should be determined by either night-time constraints (risk of frost damage to active leaves) or day-time constraints (risk of heat stress damage),with the former likely to predominate - thereby restricting the occurrence of large leaves - at high latitudes. In low latitudes, daytime maximum leaf size is predicted to increase with temperature, provided that water is plentiful. If water is restricted, however, transpiration cannot proceed at the Priestley-Taylor rate, and it quickly becomes advantageous for plants to have small leaves, which do not heat up much above the temperature of their surroundings. The difference between leaf

  7. STENOFOLIA Regulates Blade Outgrowth and Leaf Vascular Patterning in Medicago truncatula and Nicotiana sylvestris[C][W][OA

    PubMed Central

    Tadege, Million; Lin, Hao; Bedair, Mohamed; Berbel, Ana; Wen, Jiangqi; Rojas, Clemencia M.; Niu, Lifang; Tang, Yuhong; Sumner, Lloyd; Ratet, Pascal; McHale, Neil A.; Madueño, Francisco; Mysore, Kirankumar S.

    2011-01-01

    Dicot leaf primordia initiate at the flanks of the shoot apical meristem and extend laterally by cell division and cell expansion to form the flat lamina, but the molecular mechanism of lamina outgrowth remains unclear. Here, we report the identification of STENOFOLIA (STF), a WUSCHEL-like homeobox transcriptional regulator, in Medicago truncatula, which is required for blade outgrowth and leaf vascular patterning. STF belongs to the MAEWEST clade and its inactivation by the transposable element of Nicotiana tabacum cell type1 (Tnt1) retrotransposon insertion leads to abortion of blade expansion in the mediolateral axis and disruption of vein patterning. We also show that the classical lam1 mutant of Nicotiana sylvestris, which is blocked in lamina formation and stem elongation, is caused by deletion of the STF ortholog. STF is expressed at the adaxial–abaxial boundary layer of leaf primordia and governs organization and outgrowth of lamina, conferring morphogenetic competence. STF does not affect formation of lateral leaflets but is critical to their ability to generate a leaf blade. Our data suggest that STF functions by modulating phytohormone homeostasis and crosstalk directly linked to sugar metabolism, highlighting the importance of coordinating metabolic and developmental signals for leaf elaboration. PMID:21719692

  8. Leaf litter decomposition in three Adirondack lakes

    SciTech Connect

    Francis, A.J.; Quinby, H.L.; Hendrey, G.R.; Hoogendyk, C.G.

    1983-04-01

    Decomposition of terrestrial leaf litter in three Adirondack lakes with water pH values approximately 5, 6, and 7 was studied. Litter bags containing leaves of American beech, sugar maple, red maple, leather leaf, and red spruce were placed in the lakes. Samples were removed periodically over a 3-year period and analyzed for loss in weight, changes in leaf surface area, carbon, nitrogen, and bacterial populations. The rate of decomposition of litter depended on the leaf species tested as well as on the lake water in which they were incubated. Of the five leaf species tested, red maple decomposed much faster and red spruce more slowly, i.e., red maple > sugar maple > beech > leather leaf > red spruce. Further, the data indicated that the rate of decomposition of the leaves differed among the lakes in the order Woods (pH approx. 5) < Sagamore (pH approx. 6) < Panther (pH approx. 7), and that the microbial colonization of some leaf species was affected. Accumulations of leaf litter in acid lakes due to reduction in microbial decomposition may affect nutrient recycling in lake ecosystems. 8 references, 4 tables.

  9. Leaf water absorption and desorption functions for three turfgrasses

    NASA Astrophysics Data System (ADS)

    Liang, Xi; Su, Derong; Yin, Shuxia; Wang, Zhi

    2009-09-01

    SummaryPlant leaf can absorb water when the leaf is in contact with water. This happens when the rainfall is intercepted by plant leaves, where the intercepted part of rain remains on the leaf surface. When the intercepted water is either absorbed or subsequently evaporated into the atmosphere, the plant leaves can dissipate water through the desorption process until the plant is dry or rewatered. In this paper, two symptomatic models in the form of exponential functions for leaf water absorption and leaf water desorption were derived and validated by experimental data using leaves of three turfgrasses (Tall fescue, Perennial ryegrass and Kentucky bluegrass). Both the models and measured data showed that the rate of leaf water absorption was high at the low initial leaf water content and then gradually leveled off toward the saturated leaf water content. The rate of leaf water desorption was high at the high initial leaf water content then decreased drastically over time toward zero. The different plant leaves showed different exponents and other parameters of the functions which indicate the difference of plant species. Both the absorption and desorption rates were relatively higher for the Kentucky bluegrass and lower for the Tall fescue and Perennial ryegrass. The concept of specific leaf area ( SLA) was used to understand the saturated leaf water content ( C s) of the three turfgrasses. Linear relationships were found between C s and SLA. The leaf water absorption and desorption functions are useful for deriving physiological parameters of the plant such as permanent wilting leaf water content, naturally irreducible leaf water content, exponential leaf water absorption coefficient, and exponential leaf desorption coefficient, as well as for evaluating the effects of rainfall interception on plant growth and water use efficiency.

  10. The artificial leaf.

    PubMed

    Nocera, Daniel G

    2012-05-15

    corner-sharing, head-to-tail dimer. The ability to perform the oxygen-evolving reaction in water at neutral or near-neutral conditions has several consequences for the construction of the artificial leaf. The NiMoZn alloy may be used in place of Pt to generate hydrogen. To stabilize silicon in water, its surface is coated with a conducting metal oxide onto which the Co-OEC may be deposited. The net result is that immersing a triple-junction Si wafer coated with NiMoZn and Co-OEC in water and holding it up to sunlight can effect direct solar energy conversion via water splitting. By constructing a simple, stand-alone device composed of earth-abundant materials, the artificial leaf provides a means for an inexpensive and highly distributed solar-to-fuels system that employs low-cost systems engineering and manufacturing. Through this type of system, solar energy can become a viable energy supply to those in the non-legacy world. PMID:22475039

  11. Plasticity in leaf-level water relations of tropical rainforest trees in response to experimental drought.

    PubMed

    Binks, Oliver; Meir, Patrick; Rowland, Lucy; da Costa, Antonio Carlos Lola; Vasconcelos, Steel Silva; de Oliveira, Alex Antonio Ribeiro; Ferreira, Leandro; Christoffersen, Bradley; Nardini, Andrea; Mencuccini, Maurizio

    2016-07-01

    The tropics are predicted to become warmer and drier, and understanding the sensitivity of tree species to drought is important for characterizing the risk to forests of climate change. This study makes use of a long-term drought experiment in the Amazon rainforest to evaluate the role of leaf-level water relations, leaf anatomy and their plasticity in response to drought in six tree genera. The variables (osmotic potential at full turgor, turgor loss point, capacitance, elastic modulus, relative water content and saturated water content) were compared between seasons and between plots (control and through-fall exclusion) enabling a comparison between short- and long-term plasticity in traits. Leaf anatomical traits were correlated with water relation parameters to determine whether water relations differed among tissues. The key findings were: osmotic adjustment occurred in response to the long-term drought treatment; species resistant to drought stress showed less osmotic adjustment than drought-sensitive species; and water relation traits were correlated with tissue properties, especially the thickness of the abaxial epidermis and the spongy mesophyll. These findings demonstrate that cell-level water relation traits can acclimate to long-term water stress, and highlight the limitations of extrapolating the results of short-term studies to temporal scales associated with climate change. PMID:27001030

  12. Different altitude effect of leaf wax n-alkane δD values in surface soils along two vapor transport pathways, southeastern Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Bai, Yan; Fang, Xiaomin; Jia, Guodong; Sun, Jimin; Wen, Rong; Ye, Yuqing

    2015-12-01

    Here we present 76 hydrogen isotope values for leaf wax-derived n-alkanes (δDwax, being the abundance-weighted average δD values of C29 and C31n-alkanes) in surface soils along two vapor transport pathway transects running across the southeastern Tibetan Plateau (TP). The first is the South Himalayan (SH) Transect (with an altitude range of 1660-5050 m∗ above sea level, and representing the Southern Himalayan air mass), and the second a combination of the Zayu-Bomi (ZB; altitude 1468-4800 m) and Bayi-Lhasa (BL; altitude 3050-4970 m) transects, together representing the Brahmaputra-Yarlung Zangbo river valley air mass. δDwax values and their relation to altitude did exhibit some variability. Nonetheless, altitude was the predominant factor in determining soil δDwax values, with a lapse rate of -2.2‰/100 m (R2 = 0.78; n = 76) based on overall soil δDwax values, despite changes in precipitation amount, relative humidity (RH) and vegetation type. Furthermore, our εwax/rw values (the isotopic fractionation between the δDwax and δD values of river water (δDrw)) remained approximately constant at -104.5‰ (ranging between -99‰ and -110‰), confirming that the relation between altitude and isotopic hydrology (river water and precipitation) controls the n-alkane δDwax altitudinal gradients for all of the sample localities in the Southern Himalaya (SH) and the southern TP. This endorses the efficacy of using δDwax to reconstruct paleoelevation. Along the SH Transect, soil δDwax values varied from -151‰ to -264‰, with an altitudinal lapse rate of -2.4‰/100 m (R2 = 0.84, n = 32). This was due to the significant change in altitude over short distances. Along the ZB Transect, soil δDwax values varied from -174‰ to -263‰, with a lower lapse rate of -1.9‰/100 m (R2 = 0.68, n = 29). The altitudinal lapse rate was -3.3‰/100 m above 3000 m (R2 = 0.63, n = 19), and -1.35‰/100 m below 3000 m (R2 = 0.64, n = 10); in the lower sub-transect, the

  13. Assessing soybean leaf area and leaf biomass by spectral measurements

    NASA Technical Reports Server (NTRS)

    Holben, B. N.; Tucker, C. J.; Fan, C. J.

    1979-01-01

    Red and photographic infrared spectral radiances were correlated with soybean total leaf area index, green leaf area index, chlorotic leaf area index, green leaf biomass, chlorotic leaf biomass, and total biomass. The most significant correlations were found to exist between the IR/red radiance ratio data and green leaf area index and/or green leaf biomass (r squared equals 0.85 and 0.86, respectively). These findings demonstrate that remote sensing data can supply information basic to soybean canopy growth, development, and status by nondestructive determination of the green leaf area or green leaf biomass.

  14. Somatic Embryogenesis and Plant Regeneration in Sapindus mukorossi Gaertn. from Leaf-Derived Callus Induced with 6-Benzylaminopurine.

    PubMed

    Singh, Reetika; Rai, Manoj Kumar; Kumari, Nishi

    2015-09-01

    A somatic embryogenesis system was developed for Sapindus mukorossi Gaertn. from leaf explants obtained from fresh flushes of a mature tree. Callus was induced from the midrib region of leaf explants on Murashige and Skoog (MS) medium containing different concentrations of 2,4-dichlorophenoxyacetic acid or 6-benzylaminopurine. Callus induction and somatic embryogenesis was significantly influenced by the size, physiological age, and orientation of leaf explants on the culture medium and plant growth regulators. Adaxial-side-up orientation of leaf explants significantly promoted embryogenesis in comparison with abaxial-side-up orientation. Maximum number of somatic embryos was induced on MS medium supplemented with 8.88 μM 6-benzylaminopurine. Scanning electron microscopy of embryogenic callus revealed somatic embryo origin and the development of globular-, heart-, and cotyledonary-stage somatic embryos. The frequency of maturation as well as germination of somatic embryos was higher on MS medium containing 8.88 μM 6-benzylaminopurine than on medium without 6-benzylaminopurine. Plantlets which developed from somatic embryos were acclimatized successfully with 90 % survival. PMID:26208689

  15. STENOFOLIA Recruits TOPLESS to Repress ASYMMETRIC LEAVES2 at the Leaf Margin and Promote Leaf Blade Outgrowth in Medicago truncatula[C][W

    PubMed Central

    Zhang, Fei; Wang, Yewei; Li, Guifen; Tang, Yuhong; Kramer, Elena M.; Tadege, Million

    2014-01-01

    The Medicago truncatula WUSCHEL-related homeobox (WOX) gene, STENOFOLIA (STF), plays a key role in leaf blade outgrowth by promoting cell proliferation at the adaxial-abaxial junction. STF functions primarily as a transcriptional repressor, but the underlying molecular mechanism is unknown. Here, we report the identification of a protein interaction partner and a direct target, shedding light on the mechanism of STF function. Two highly conserved motifs in the C-terminal domain of STF, the WUSCHEL (WUS) box and the STF box, cooperatively recruit TOPLESS (Mt-TPL) family corepressors, and this recruitment is required for STF function, as deletion of these two domains (STFdel) impaired blade outgrowth whereas fusing Mt-TPL to STFdel restored function. The homeodomain motif is required for direct repression of ASYMMETRIC LEAVES2 (Mt-AS2), silencing of which partially rescues the stf mutant phenotype. STF and LAMINALESS1 (LAM1) are functional orthologs. A single amino acid (Asn to Ile) substitution in the homeodomain abolished the repression of Mt-AS2 and STF’s ability to complement the lam1 mutant of Nicotiana sylvestris. Our data together support a model in which STF recruits corepressors to transcriptionally repress its targets during leaf blade morphogenesis. We propose that recruitment of TPL/TPL-related proteins may be a common mechanism in the repressive function of modern/WUS clade WOX genes. PMID:24585835

  16. Spectroscopic Measurement of Leaf Water Status

    NASA Technical Reports Server (NTRS)

    Goetz, Alexander F. H.; Boardman, Joseph W.

    1995-01-01

    A leaf drying experiment was carried out in the laboratory in which simultaneous spectral reflectance in the 350-2450 nm region, and leaf weights, were measured at 10 second intervals over a 40 minute period. As the leaf water weight dropped from approximately 60 to 38%. a nearly-linear rise in reflectance at all wavelengths beyond 1000 nm was observed. A principal components analysis of the time series of spectra in the 2000-2500 nm wavelength region showed that over 99% of the variance in the spectra, that were individually scaled to have a sum equal to that of the mean spectrum and subsequently mean corrected, was in the first component. This result shows that it is feasible to determine leaf water content remotely with an imaging spectrometer independent of the surface irradiance effects caused by topography.

  17. A hotspot model for leaf canopies

    NASA Technical Reports Server (NTRS)

    Jupp, David L. B.; Strahler, Alan H.

    1991-01-01

    The hotspot effect, which provides important information about canopy structure, is modeled using general principles of environmental physics as driven by parameters of interest in remote sensing, such as leaf size, leaf shape, leaf area index, and leaf angle distribution. Specific examples are derived for canopies of horizontal leaves. The hotspot effect is implemented within the framework of the model developed by Suits (1972) for a canopy of leaves to illustrate what might occur in an agricultural crop. Because the hotspot effect arises from very basic geometrical principles and is scale-free, it occurs similarly in woodlands, forests, crops, rough soil surfaces, and clouds. The scaling principles advanced are also significant factors in the production of image spatial and angular variance and covariance which can be used to assess land cover structure through remote sensing.

  18. Yellow leaf blotch

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Yellow leaf blotch occurs worldwide in temperate climates. The disease is reported from countries in Asia, Australasia, Oceania, Europe, North America, Central America, the West Indies, and South America. In the northern Great Plains of North America, it is often the major leaf disease on alfalfa....

  19. Effects of Nitrogen on Mesophyll Cell Division and Epidermal Cell Elongation in Tall Fescue Leaf Blades 1

    PubMed Central

    MacAdam, Jennifer W.; Volenec, Jeffrey J.; Nelson, Curtis J.

    1989-01-01

    Leaf elongation rate (LER) in grasses is dependent on epidermal cell supply (number) and on rate and duration of epidermal cell elongation. Nitrogen (N) fertilization increases LER. Longitudinal sections from two genotypes of tall fescue (Festuca arundinacea Schreb.), which differ by 50% in LER, were used to quantify the effects of N on the components of epidermal cell elongation and on mesophyll cell division. Rate and duration of epidermal cell elongation were determined by using a relationship between cell length and displacement velocity derived from the continuity equation. Rate of epidermal cell elongation was exponential. Relative rates of epidermal cell elongation increased by 9% with high N, even though high N increased LER by 89%. Duration of cell elongation was approximately 20 h longer in the high- than in the low-LER genotype regardless of N treatment. The percentage of mesophyll cells in division was greater in the high- than in the low-LER genotype. This increased with high N in both genotypes, indicating that LER increased with cell supply. Division of mesophyll cells adjacent to abaxial epidermal cells continued after epidermal cell division stopped, until epidermal cells had elongated to a mean length of 40 micrometers in the high-LER and a mean length of 50 micrometers in the low-LER genotype. The cell cycle length for mesophyll cells was calculated to be 12 to 13 hours. Nitrogen increased mesophyll cell number more than epidermal cell number: in both genotypes, the final number of mesophyll cells adjacent to each abaxial epidermal cell was 10 with low N and 14 with high N. A spatial model is used to describe three cell development processes relevant to leaf growth. It illustrates the overlap of mesophyll cell division and epidermal cell elongation, and the transition from epidermal cell elongation to secondary cell wall deposition. PMID:16666581

  20. Biometamaterials: Black Ultrathin Gold Film Fabricated on Lotus Leaf.

    PubMed

    Ebihara, Yuusuke; Ota, Ryoichi; Noriki, Takahiro; Shimojo, Masayuki; Kajikawa, Kotaro

    2015-01-01

    We report on a black metamaterial of gold fabricated on a lotus leaf that was used as a template. In spite of the extremely thin gold coating (10-nm thick) on the lotus leaf, the surface shows reflectivity below 0.01 over the entire visible spectral range. Finite-difference time-domain (FDTD) calculations suggest that the low reflectivity stems from the secondary structures on the lotus leaf, where randomly oriented nanorods are distributed. PMID:26530514

  1. Biometamaterials: Black Ultrathin Gold Film Fabricated on Lotus Leaf

    PubMed Central

    Ebihara, Yuusuke; Ota, Ryoichi; Noriki, Takahiro; Shimojo, Masayuki; Kajikawa, Kotaro

    2015-01-01

    We report on a black metamaterial of gold fabricated on a lotus leaf that was used as a template. In spite of the extremely thin gold coating (10-nm thick) on the lotus leaf, the surface shows reflectivity below 0.01 over the entire visible spectral range. Finite-difference time-domain (FDTD) calculations suggest that the low reflectivity stems from the secondary structures on the lotus leaf, where randomly oriented nanorods are distributed. PMID:26530514

  2. Global variability in leaf respiration in relation to climate and leaf traits

    NASA Astrophysics Data System (ADS)

    Atkin, Owen K.

    2015-04-01

    Leaf respiration plays a vital role in regulating ecosystem functioning and the Earth's climate. Because of this, it is imperative that that Earth-system, climate and ecosystem-level models be able to accurately predict variations in rates of leaf respiration. In the field of photosynthesis research, the F/vC/B model has enabled modellers to accurately predict variations in photosynthesis through time and space. By contrast, we lack an equivalent biochemical model to predict variations in leaf respiration. Consequently, we need to rely on phenomenological approaches to model variations in respiration across the Earth's surface. Such approaches require that we develop a thorough understanding of how rates of respiration vary among species and whether global environmental gradients play a role in determining variations in leaf respiration. Dealing with these issues requires that data sets be assembled on rates of leaf respiration in biomes across the Earth's surface. In this talk, I will use a newly-assembled global database on leaf respiration and associated traits (including photosynthesis) to highlight variation in leaf respiration (and the balance between respiration and photosynthesis) across global gradients in growth temperature and aridity.

  3. Do plant mites commonly prefer the underside of leaves?

    PubMed

    Sudo, Masaaki; Osakabe, Masahiro

    2011-09-01

    The adaxial (upper) and abaxial (lower) surfaces of a plant leaf provide heterogeneous habitats for small arthropods with different environmental conditions, such as light, humidity, and surface morphology. As for plant mites, some agricultural pest species and their natural enemies have been observed to favor the abaxial leaf surface, which is considered an adaptation to avoid rain or solar ultraviolet radiation. However, whether such a preference for the leaf underside is a common behavioral trait in mites on wild vegetation remains unknown. The authors conducted a 2-year survey on the foliar mite assemblage found on Viburnum erosum var. punctatum, a deciduous shrub on which several mite taxa occur throughout the seasons, and 14 sympatric tree or shrub species in secondary broadleaf-forest sites in Kyoto, west-central Japan. We compared adaxial-abaxial surface distributions of mites among mite taxa, seasons, and morphology of host leaves (presence/absence of hairs and domatia). On V. erosum var. punctatum, seven of 11 distinguished mite taxa were significantly distributed in favor of abaxial leaf surfaces and the trend was seasonally stable, except for Eriophyoidea. Mite assemblages on 15 plant species were significantly biased towards the abaxial leaf surfaces, regardless of surface morphology. Our data suggest that many mite taxa commonly prefer to stay on abaxial leaf surfaces in wild vegetation. Oribatida displayed a relatively neutral distribution, and in Tenuipalpidae, the ratio of eggs collected from the adaxial versus the abaxial side was significantly higher than the ratio of the motile individuals, implying that some mite taxa exploit adaxial leaf surfaces as habitat. PMID:21472503

  4. Modification and co-option of leaf developmental programs for the acquisition of flat structures in monocots: unifacial leaves in Juncus and cladodes in Asparagus

    PubMed Central

    Nakayama, Hokuto; Yamaguchi, Takahiro; Tsukaya, Hirokazu

    2013-01-01

    It has been suggested that modification and co-option of existing gene regulatory networks (GRNs) play an important role in the morphological diversity. In plants, leaf development is one of active research areas, and the basic GRN for leaf development is beginning to be understood. Moreover, leaves show wide variation in their form, and some of this variation is thought to be the result of adaptation. Thus, leaves and leaf-like organs are an emerging and interesting model to reveal how existing GRNs give rise to novel forms and architectures during evolution. In this review, we highlight recent findings in evo-devo studies, especially on Juncus unifacial leaves, which are composed of lamina with abaxialized identities, and Asparagus cladodes, which are leaf-like organs at the axils of scale leaves. Based on these studies, we discuss how flat structures have evolved and morphologically diversified in shoot systems of monocot species, focusing on the modification and co-option of GRN for leaf development. PMID:23847648

  5. Leaf growth is conformal.

    PubMed

    Alim, Karen; Armon, Shahaf; Shraiman, Boris I; Boudaoud, Arezki

    2016-01-01

    Growth pattern dynamics lie at the heart of morphogenesis. Here, we investigate the growth of plant leaves. We compute the conformal transformation that maps the contour of a leaf at a given stage onto the contour of the same leaf at a later stage. Based on the mapping we predict the local displacement field in the leaf blade and find it to agree with the experimentally measured displacement field to 92%. This approach is applicable to any two-dimensional system with locally isotropic growth, enabling the deduction of the whole growth field just from observation of the tissue contour. PMID:27597439

  6. Wind increases leaf water use efficiency.

    PubMed

    Schymanski, Stanislaus J; Or, Dani

    2016-07-01

    A widespread perception is that, with increasing wind speed, transpiration from plant leaves increases. However, evidence suggests that increasing wind speed enhances carbon dioxide (CO2 ) uptake while reducing transpiration because of more efficient convective cooling (under high solar radiation loads). We provide theoretical and experimental evidence that leaf water use efficiency (WUE, carbon uptake per water transpired) commonly increases with increasing wind speed, thus improving plants' ability to conserve water during photosynthesis. Our leaf-scale analysis suggests that the observed global decrease in near-surface wind speeds could have reduced WUE at a magnitude similar to the increase in WUE attributed to global rise in atmospheric CO2 concentrations. However, there is indication that the effect of long-term trends in wind speed on leaf gas exchange may be compensated for by the concurrent reduction in mean leaf sizes. These unintuitive feedbacks between wind, leaf size and water use efficiency call for re-evaluation of the role of wind in plant water relations and potential re-interpretation of temporal and geographic trends in leaf sizes. PMID:26714739

  7. Leaf Tissue Senescence

    PubMed Central

    Manos, Peter J.; Goldthwaite, Jonathan

    1975-01-01

    During winter, excised leaf tissue from Rumex obtusifolius degrades chlorophyll at twice the summer rate but the plant hormones, gibberellic acid and zeatin, inhibit the senescence rate by a constant percentage, regardless of season. PMID:16659225

  8. Dorsoventral variations in dark chilling effects on photosynthesis and stomatal function in Paspalum dilatatum leaves

    PubMed Central

    Soares-Cordeiro, Ana Sofia; Driscoll, Simon P.; Arrabaça, Maria Celeste; Foyer, Christine H.

    2011-01-01

    The effects of dark chilling on the leaf-side-specific regulation of photosynthesis were characterized in the C4 grass Paspalum dilatatum. CO2- and light-response curves for photosynthesis and associated parameters were measured on whole leaves and on each leaf side independently under adaxial and abaxial illumination before and after plants were exposed to dark chilling for one or two consecutive nights. The stomata closed on the adaxial sides of the leaves under abaxial illumination and no CO2 uptake could be detected on this surface. However, high rates of whole leaf photosynthesis were still observed because CO2 assimilation rates were increased on the abaxial sides of the leaves under abaxial illumination. Under adaxial illumination both leaf surfaces contributed to the inhibition of whole leaf photosynthesis observed after one night of chilling. After two nights of chilling photosynthesis remained inhibited on the abaxial side of the leaf but the adaxial side had recovered, an effect related to increased maximal ribulose-1,5-bisphosphate carboxylation rates (Vcmax) and enhanced maximal electron transport rates (Jmax). Under abaxial illumination, whole leaf photosynthesis was decreased only after the second night of chilling. The chilling-dependent inhibition of photosynthesis was located largely on the abaxial side of the leaf and was related to decreased Vcmax and Jmax, but not to the maximal phosphoenolpyruvate carboxylase carboxylation rate (Vpmax). Each side of the leaf therefore exhibits a unique sensitivity to stress and recovery. Side-specific responses to stress are related to differences in the control of enzyme and photosynthetic electron transport activities. PMID:21030386

  9. Sites of Action of Elevated CO2 on Leaf Development in Rice: Discrimination between the Effects of Elevated CO2 and Nitrogen Deficiency

    PubMed Central

    Tsutsumi, Koichi; Konno, Masae; Miyazawa, Shin-Ichi; Miyao, Mitsue

    2014-01-01

    Elevated CO2 concentrations (eCO2) trigger various plant responses. Despite intensive studies of these responses, the underlying mechanisms remain obscure. In this work, we investigated when and how leaf physiology and anatomy are affected by eCO2 in rice plants. We analyzed the most recently fully expanded leaves that developed successively after transfer of the plant to eCO2. To discriminate between the effects of eCO2 and those of nitrogen deficiency, we used three different levels of N application. We found that a decline in the leaf soluble protein content (on a leaf area basis) at eCO2 was only observed under N deficiency. The length and width of the leaf blade were reduced by both eCO2 and N deficiency, whereas the blade thickness was increased by eCO2 but was not affected by N deficiency. The change in length by eCO2 became detectable in the secondly fully expanded leaf, and those in width and thickness in the thirdly fully expanded leaf, which were at the leaf developmental stages P4 and P3, respectively, at the onset of the eCO2 treatment. The decreased blade length at eCO2 was associated with a decrease in the epidermal cell number on the adaxial side and a reduction in cell length on the abaxial side. The decreased width resulted from decreased numbers of small vascular bundles and epidermal cell files. The increased thickness was ascribed mainly to enhanced development of bundle sheath extensions at the ridges of vascular bundles. These observations enable us to identify the sites of action of eCO2 on rice leaf development. PMID:24406628

  10. Deer predation on leaf miners via leaf abscission

    NASA Astrophysics Data System (ADS)

    Yamazaki, Kazuo; Sugiura, Shinji

    2008-03-01

    The evergreen oak Quercus gilva Blume sheds leaves containing mines of the leaf miner Stigmella sp. (Lepidoptera: Nepticulidae) earlier than leaves with no mines in early spring in Nara, central Japan. The eclosion rates of the leaf miner in abscised and retained leaves were compared in the laboratory to clarify the effects of leaf abscission on leaf miner survival in the absence of deer. The leaf miner eclosed successfully from both fallen leaves and leaves retained on trees. However, sika deer ( Cervus nippon centralis Kishida) feed on the fallen mined leaves. Field observations showed that deer consume many fallen leaves under Q. gilva trees, suggesting considerable mortality of leaf miners due to deer predation via leaf abscission. This is a previously unreported relationship between a leaf miner and a mammalian herbivore via leaf abscission.

  11. Droplet Impacting a Cantilever: A Leaf-Raindrop System

    NASA Astrophysics Data System (ADS)

    Gart, Sean; Mates, Joseph E.; Megaridis, Constantine M.; Jung, Sunghwan

    2015-04-01

    Previous studies show that air pollution and wind erosion, which damage a leaf's epicuticular wax layer, can change leaf surface properties from hydrophobic to hydrophilic. However, the dynamic response of a damaged leaf to a raindrop impact has not been investigated and could clarify the direct influence of changes in wettability on early leaf abscission. In this article, we investigate how leaves with different surface properties respond to falling raindrops, viewing this as a unique system of coupled elasticity and drop dynamics. An elastic beam with tunable surface wettability properties is used as a simple leaf model. We find that wettable beams experience much higher torque and bending energy than nonwettable beams. This is because a drop sticks to a wettable beam, while a drop falls off a nonwettable beam. An analytical model using momentum balance and simple cantilever beam theory quantifies the bending energy and torque experienced by wettable and nonwettable beams. The results elucidate the potential damage caused by raindrops impacting a leaf as a function of its surface wettability and are correlated with environmental factors contributing to premature changes of leaf surface properties.

  12. PIMA cotton leaf transpiration analysis using the wallmodel that accounts for liquid water movement

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Leaf transpiration of eight genotypes of Pima cotton was measured in the field of the Maricopa Agricultural Center in August 1994 at the University of Arizona. Photomicrographs of leaf cross-sections and of the leaf surfaces were scanned and analyzed with the image analysis software. The data were ...

  13. Mueller matrix of a dicot leaf

    NASA Astrophysics Data System (ADS)

    Vanderbilt, Vern C.; Daughtry, Craig S. T.

    2012-06-01

    A better understanding of the information contained in the spectral, polarized bidirectional reflectance and transmittance of leaves may lead to improved techniques for identifying plant species in remotely sensed imagery as well as better estimates of plant moisture and nutritional status. Here we report an investigation of the optical polarizing properties of several leaves of one species, Cannabis sativa, represented by a 3x3 Mueller matrix measured over the wavelength region 400-2,400 nm. Our results support the hypothesis that the leaf surface alters the polarization of incident light - polarizing off nadir, unpolarized incident light, for example - while the leaf volume tends to depolarized incident polarized light.

  14. Damped leaf flexure hinge

    NASA Astrophysics Data System (ADS)

    Chen, Zhong; Chen, Guisheng; Zhang, Xianmin

    2015-05-01

    Flexure-based mechanism like compliant actuation system embeds complex dynamics that will reduce the control bandwidth and limits their dynamic positioning precision. This paper presents a theoretical model of a leaf flexure hinge with damping layers using strain energy method and Kelvin damping model. The modified loss factor of the damped leaf flexure hinge is derived, and the equivalent viscous damping coefficient of the damped leaf hinge is obtained, which could be used to improve the pseudo-rigid-model. The free vibration signals of the hinge in three different damping configurations are measured. The experimental modal analysis also is performed on the three kinds of damped leaf flexure hinges in order to evaluate their 1st order bending natural frequency and vibration-suppressing effects. The evaluation of modified loss factor model also is performed. The experimental results indicate that the constrained layer damping can enhance the structure damping of the hinge even if only single damping layer each side, the modified loss factor model can get good predicts of a damped leaf flexure hinge in the frequency range below 1st order natural frequency, and it is necessary that the dimensional parameters of the damping layers and basic layer of the hinge should be optimized for simplification at the mechanism's design stage.

  15. Damped leaf flexure hinge.

    PubMed

    Chen, Zhong; Chen, Guisheng; Zhang, Xianmin

    2015-05-01

    Flexure-based mechanism like compliant actuation system embeds complex dynamics that will reduce the control bandwidth and limits their dynamic positioning precision. This paper presents a theoretical model of a leaf flexure hinge with damping layers using strain energy method and Kelvin damping model. The modified loss factor of the damped leaf flexure hinge is derived, and the equivalent viscous damping coefficient of the damped leaf hinge is obtained, which could be used to improve the pseudo-rigid-model. The free vibration signals of the hinge in three different damping configurations are measured. The experimental modal analysis also is performed on the three kinds of damped leaf flexure hinges in order to evaluate their 1st order bending natural frequency and vibration-suppressing effects. The evaluation of modified loss factor model also is performed. The experimental results indicate that the constrained layer damping can enhance the structure damping of the hinge even if only single damping layer each side, the modified loss factor model can get good predicts of a damped leaf flexure hinge in the frequency range below 1st order natural frequency, and it is necessary that the dimensional parameters of the damping layers and basic layer of the hinge should be optimized for simplification at the mechanism's design stage. PMID:26026549

  16. Wind-induced leaf transpiration

    NASA Astrophysics Data System (ADS)

    Huang, Cheng-Wei; Chu, Chia-Ren; Hsieh, Cheng-I.; Palmroth, Sari; Katul, Gabriel G.

    2015-12-01

    While the significance of leaf transpiration (fe) on carbon and water cycling is rarely disputed, conflicting evidence has been reported on how increasing mean wind speed (U) impacts fe from leaves. Here, conditions promoting enhancement or suppression of fe with increasing U for a wide range of environmental conditions are explored numerically using leaf-level gas exchange theories that combine a stomatal conductance model based on optimal water use strategies (maximizing the 'net' carbon gain at a given fe), energy balance considerations, and biochemical demand for CO2. The analysis showed monotonic increases in fe with increasing U at low light levels. However, a decline in modeled fe with increasing U were predicted at high light levels but only in certain instances. The dominant mechanism explaining this decline in modeled fe with increasing U is a shift from evaporative cooling to surface heating at high light levels. New and published sap flow measurements for potted Pachira macrocarpa and Messerschmidia argentea plants conducted in a wind tunnel across a wide range of U (2 - 8 m s-1) and two different soil moisture conditions were also employed to assess how fe varies with increasing U. The radiative forcing imposed in the wind tunnel was only restricted to the lower end of expected field conditions. At this low light regime, the findings from the wind tunnel experiments were consistent with the predicted trends.

  17. Raspberry leaf curl virus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Raspberry leaf curl virus (RLCV) is limited to hosts in the genus Rubus and is transmitted persistently by the small raspberry aphid, Aphis rubicola Oestlund. It is found only in North America, principally in the northeastern United States and southeastern Canada and in the Rocky Mountain regions of...

  18. Maple Leaf Outdoor Centre.

    ERIC Educational Resources Information Center

    Maguire, Molly; Gunton, Ric

    2000-01-01

    Maple Leaf Outdoor Centre (Ontario) has added year-round outdoor education facilities and programs to help support its summer camp for disadvantaged children. Schools, youth centers, religious groups, and athletic teams conduct their own programs, collaborate with staff, or use staff-developed programs emphasizing adventure education and personal…

  19. Bacterial leaf spot

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bacterial leaf spot has been reported in Australia (Queensland), Egypt, El Salvador, India, Japan, Nicaragua, Sudan, and the United States (Florida, Iowa, Kansas, Maryland, and Wisconsin). It occasionally causes locally severe defoliation and post-emergence damping-off and stunting. The disease is...

  20. Pharmacognostic evaluation of Cayratia trifolia (Linn.) leaf

    PubMed Central

    Kumar, Dinesh; Gupta, Jyoti; Kumar, Sunil; Arya, Renu; Kumar, Tarun; Gupta, Ankit

    2012-01-01

    Objective To present a detailed pharmacognostic study of the leaf of Cayratia trifolia (C. trifolia) Linn. (Vitaceae), an important plant in the Indian system of medicine. Methods The macroscopy, microscopy, physiochemical analysis, preliminary testing, fluorescence analysis of powder of the plant and other WHO recommended methods for standardization were investigated. Results Leaves are trifoliolated with petioles (2–3 cm) long. Leaflets are ovate to oblong-ovate, (2–8 cm) long, (1.5–5 cm) wide, pointed at the tip. The leaf surface shows the anisocytic type stomata covered with guard cells followed by epidermis layer. Leaf surface contents including veins, vein islet and vein termination were also determined. Transverse section of leaf shows the epidermis layer followed by cuticle layer and vascular bandles (xylem and phloem). The mesophyll is differentiated into palisade and spongy parenchyma. Abundant covering trichomes emerge from the upper epidermis. Trichomes are uniseriate and multicellular. Strips of collenchyma are present below and upper layer of epidermis. Conclusions It can be concluded that the pharmacognostic profile of the C. trifolia is helpful in developing standards for quality, purity and sample identification. PMID:23569825

  1. Developing multi-tracer approaches to constrain the parameterisation of leaf and soil CO2 and H2O exchange in land surface models

    NASA Astrophysics Data System (ADS)

    Ogée, Jerome; Wehr, Richard; Commane, Roisin; Launois, Thomas; Meredith, Laura; Munger, Bill; Nelson, David; Saleska, Scott; Zahniser, Mark; Wofsy, Steve; Wingate, Lisa

    2016-04-01

    The net flux of carbon dioxide between the land surface and the atmosphere is dominated by photosynthesis and soil respiration, two of the largest gross CO2 fluxes in the carbon cycle. More robust estimates of these gross fluxes could be obtained from the atmospheric budgets of other valuable tracers, such as carbonyl sulfide (COS) or the carbon and oxygen isotope compositions (δ13C and δ18O) of atmospheric CO2. Over the past decades, the global atmospheric flask network has measured the inter-annual and intra-annual variations in the concentrations of these tracers. However, knowledge gaps and a lack of high-resolution multi-tracer ecosystem-scale measurements have hindered the development of process-based models that can simulate the behaviour of each tracer in response to environmental drivers. We present novel datasets of net ecosystem COS, 13CO2 and CO18O exchange and vertical profile data collected over 3 consecutive growing seasons (2011-2013) at the Harvard forest flux site. We then used the process-based model MuSICA (multi-layer Simulator of the Interactions between vegetation Canopy and the Atmosphere) to include the transport, reaction, diffusion and production of each tracer within the forest and exchanged with the atmosphere. Model simulations over the three years captured well the impact of diurnally and seasonally varying environmental conditions on the net ecosystem exchange of each tracer. The model also captured well the dynamic vertical features of tracer behaviour within the canopy. This unique dataset and model sensitivity analysis highlights the benefit in the collection of multi-tracer high-resolution field datasets and the developement of multi-tracer land surface models to provide valuable constraints on photosynthesis and respiration across scales in the near future.

  2. Leaf wetness distribution in a heterogeneous agricultural landscape

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Spatial variability of leaf wetness quantity is a rising concern for remote sensing and hydrology. The presence of liquid water on the plant surface may impact the ability of new and future remote sensing technologies to measure surface soil moisture. Furthermore, the potential recharge of surface...

  3. First report of root rot of lentil caused by Aphanomyces euteiches in Idaho

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In June 2008, apparently diseased lentil plants (Lens culinaris L. cv. Crimson) were observed in a production field in Kendrick, ID. Symptoms included stunting, leaf chlorosis, reddening of abaxial leaf surfaces, browning of entire root systems and root necrosis. Roots of symptomatic plants were sur...

  4. Hessian fly (Mayetiola destructor) interactions with barley, rice, and wheat seedlings

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A choice test revealed that Hessian fly adults deposited approximately three times more eggs on wheat seedlings than on barley or rice seedlings. On a barley seedling, 49.4% of eggs were deposited on either the abaxial leaf-surface or the coleoptile and first leaf-sheath (C&FLS), where newly hatche...

  5. Accumulation of semi-volatile organic compounds in moss (Sphagnum Species) and spruce needles (Picea Mariana): Whole-leaf absorption vs. surface adsorption processes

    SciTech Connect

    Hornbuckle, K.C.; Eisenreich, S.J.

    1996-12-31

    Vapor exchange of semi-volatile organic compounds (SOCs) with plant surfaces may control the fate of SOCS far from their original sources. For example, plants may act as sinks for released SOCs by adsorbing the compounds and burying them upon the plant`s death. Evidence for this hypothesis lies in the accumulation of SOCs in peat moss. Alternatively, plants may act as temporary {open_quote}resting points{close_quote} for long-range transport of the compounds from warmer regions to cooler regions. Studies that show higher SOC concentrations in plants collected from cooler parts of the globe are evidence for this hypothesis. Whether vapor-phase SOCs are taken up or released by plants is expected to depend on characteristics of the compound, the plant, and the local climate. Theoretically, it has been predicted that temperature and SOC hydrophobicity should dominate vapor exchange. The effect of these two factors on vapor-plant exchange has been examined through two concurrent and related studies. The first study concerns the vapor SOC dynamics in a semi-remote forested bog in northern Minnesota. The second study concerns the measured distribution between vapor and plant-associated SOCs in the same bog.

  6. Evaluation of Three Protein-Extraction Methods for Proteome Analysis of Maize Leaf Midrib, a Compound Tissue Rich in Sclerenchyma Cells.

    PubMed

    Wang, Ning; Wu, Xiaolin; Ku, Lixia; Chen, Yanhui; Wang, Wei

    2016-01-01

    Leaf morphology is closely related to the growth and development of maize (Zea mays L.) plants and final kernel production. As an important part of the maize leaf, the midrib holds leaf blades in the aerial position for maximum sunlight capture. Leaf midribs of adult plants contain substantial sclerenchyma cells with heavily thickened and lignified secondary walls and have a high amount of phenolics, making protein extraction and proteome analysis difficult in leaf midrib tissue. In the present study, three protein-extraction methods that are commonly used in plant proteomics, i.e., phenol extraction, TCA/acetone extraction, and TCA/acetone/phenol extraction, were qualitatively and quantitatively evaluated based on 2DE maps and MS/MS analysis using the midribs of the 10th newly expanded leaves of maize plants. Microscopy revealed the existence of substantial amounts of sclerenchyma underneath maize midrib epidermises (particularly abaxial epidermises). The spot-number order obtained via 2DE mapping was as follows: phenol extraction (655) > TCA/acetone extraction (589) > TCA/acetone/phenol extraction (545). MS/MS analysis identified a total of 17 spots that exhibited 2-fold changes in abundance among the three methods (using phenol extraction as a control). Sixteen of the proteins identified were hydrophilic, with GRAVY values ranging from -0.026 to -0.487. For all three methods, we were able to obtain high-quality protein samples and good 2DE maps for the maize leaf midrib. However, phenol extraction produced a better 2DE map with greater resolution between spots, and TCA/acetone extraction produced higher protein yields. Thus, this paper includes a discussion regarding the possible reasons for differential protein extraction among the three methods. This study provides useful information that can be used to select suitable protein extraction methods for the proteome analysis of recalcitrant plant tissues that are rich in sclerenchyma cells. PMID:27379139

  7. Evaluation of Three Protein-Extraction Methods for Proteome Analysis of Maize Leaf Midrib, a Compound Tissue Rich in Sclerenchyma Cells

    PubMed Central

    Wang, Ning; Wu, Xiaolin; Ku, Lixia; Chen, Yanhui; Wang, Wei

    2016-01-01

    Leaf morphology is closely related to the growth and development of maize (Zea mays L.) plants and final kernel production. As an important part of the maize leaf, the midrib holds leaf blades in the aerial position for maximum sunlight capture. Leaf midribs of adult plants contain substantial sclerenchyma cells with heavily thickened and lignified secondary walls and have a high amount of phenolics, making protein extraction and proteome analysis difficult in leaf midrib tissue. In the present study, three protein-extraction methods that are commonly used in plant proteomics, i.e., phenol extraction, TCA/acetone extraction, and TCA/acetone/phenol extraction, were qualitatively and quantitatively evaluated based on 2DE maps and MS/MS analysis using the midribs of the 10th newly expanded leaves of maize plants. Microscopy revealed the existence of substantial amounts of sclerenchyma underneath maize midrib epidermises (particularly abaxial epidermises). The spot-number order obtained via 2DE mapping was as follows: phenol extraction (655) > TCA/acetone extraction (589) > TCA/acetone/phenol extraction (545). MS/MS analysis identified a total of 17 spots that exhibited 2-fold changes in abundance among the three methods (using phenol extraction as a control). Sixteen of the proteins identified were hydrophilic, with GRAVY values ranging from -0.026 to -0.487. For all three methods, we were able to obtain high-quality protein samples and good 2DE maps for the maize leaf midrib. However, phenol extraction produced a better 2DE map with greater resolution between spots, and TCA/acetone extraction produced higher protein yields. Thus, this paper includes a discussion regarding the possible reasons for differential protein extraction among the three methods. This study provides useful information that can be used to select suitable protein extraction methods for the proteome analysis of recalcitrant plant tissues that are rich in sclerenchyma cells. PMID:27379139

  8. Differentiation of C4 photosynthesis along a leaf developmental gradient in two Cleome species having different forms of Kranz anatomy.

    PubMed

    Koteyeva, Nuria K; Voznesenskaya, Elena V; Cousins, Asaph B; Edwards, Gerald E

    2014-07-01

    In family Cleomaceae there are NAD-malic enzyme-type C4 species having different forms of leaf anatomy. Leaves of Cleome angustifolia have Glossocardioid-type anatomy with a single complex Kranz unit which surrounds all the veins, while C. gynandra has Atriplicoid anatomy with multiple Kranz units, each surrounding an individual vein. Biochemical and ultrastructural differentiation of mesophyll (M) and bundle sheath (BS) cells were studied along a developmental gradient, from the leaf base (youngest) to the tip (mature). Initially, there is cell-specific expression of certain photosynthetic enzymes, which subsequently increase along with structural differentiation. At the base of the leaf, following division of ground tissue to form M and BS cells which are structurally similar, there is selective localization of Rubisco and glycine decarboxylase to BS cells. Thus, a biochemical C3 default stage, with Rubisco expression in both cell types, does not occur. Additionally, phosphoenolpyruvate carboxylase (PEPC) is selectively expressed in M cells near the base. Surprisingly, in both species, an additional layer of spongy M cells on the abaxial side of the leaf has the same differentiation with PEPC, even though it is not in contact with BS cells. During development along the longitudinal gradient there is structural differentiation of the cells, chloroplasts, and mitochondria, resulting in complete formation of Kranz anatomy. In both species, development of the C4 system occurs similarly, irrespective of having very different types of Kranz anatomy, different ontogenetic origins of BS and M, and independent evolutionary origins of C4 photosynthesis. PMID:24550438

  9. Differentiation of C4 photosynthesis along a leaf developmental gradient in two Cleome species having different forms of Kranz anatomy

    PubMed Central

    Koteyeva, Nuria K.; Voznesenskaya, Elena V.; Cousins, Asaph B.; Edwards, Gerald E.

    2014-01-01

    In family Cleomaceae there are NAD-malic enzyme-type C4 species having different forms of leaf anatomy. Leaves of Cleome angustifolia have Glossocardioid-type anatomy with a single complex Kranz unit which surrounds all the veins, while C. gynandra has Atriplicoid anatomy with multiple Kranz units, each surrounding an individual vein. Biochemical and ultrastructural differentiation of mesophyll (M) and bundle sheath (BS) cells were studied along a developmental gradient, from the leaf base (youngest) to the tip (mature). Initially, there is cell-specific expression of certain photosynthetic enzymes, which subsequently increase along with structural differentiation. At the base of the leaf, following division of ground tissue to form M and BS cells which are structurally similar, there is selective localization of Rubisco and glycine decarboxylase to BS cells. Thus, a biochemical C3 default stage, with Rubisco expression in both cell types, does not occur. Additionally, phosphoenolpyruvate carboxylase (PEPC) is selectively expressed in M cells near the base. Surprisingly, in both species, an additional layer of spongy M cells on the abaxial side of the leaf has the same differentiation with PEPC, even though it is not in contact with BS cells. During development along the longitudinal gradient there is structural differentiation of the cells, chloroplasts, and mitochondria, resulting in complete formation of Kranz anatomy. In both species, development of the C4 system occurs similarly, irrespective of having very different types of Kranz anatomy, different ontogenetic origins of BS and M, and independent evolutionary origins of C4 photosynthesis. PMID:24550438

  10. Leaf absorbance and photosynthesis

    NASA Technical Reports Server (NTRS)

    Schurer, Kees

    1994-01-01

    The absorption spectrum of a leaf is often thought to contain some clues to the photosynthetic action spectrum of chlorophyll. Of course, absorption of photons is needed for photosynthesis, but the reverse, photosynthesis when there is absorption, is not necessarily true. As a check on the existence of absorption limits we measured spectra for a few different leaves. Two techniques for measuring absorption have been used, viz. the separate determination of the diffuse reflectance and the diffuse transmittance with the leaf at a port of an integrating sphere and the direct determination of the non-absorbed fraction with the leaf in the sphere. In a cross-check both methods yielded the same results for the absorption spectrum. The spectrum of a Fuchsia leaf, covering the short-wave region from 350 to 2500 nm, shows a high absorption in UV, blue and red, the well known dip in the green and a steep fall-off at 700 nm. Absorption drops to virtually zero in the near infrared, with subsequent absorptions, corresponding to the water absorption bands. In more detailed spectra, taken at 5 nm intervals with a 5 nm bandwidth, differences in chlorophyll content show in the different depths of the dip around 550 nm and in a small shift of the absorption edge at 700 nm. Spectra for Geranium (Pelargonium zonale) and Hibiscus (with a higher chlorophyll content) show that the upper limit for photosynthesis can not be much above 700 nm. No evidence, however, is to be seen of a lower limit for photosynthesis and, in fact, some experiments down to 300 nm still did not show a decrease of the absorption although it is well recognized that no photosynthesis results with 300 nm wavelengths.

  11. Effect of curvature on the backscattering from a leaf

    NASA Technical Reports Server (NTRS)

    Sarabandi, K.; Senior, T. B. A.; Ulaby, F. T.

    1988-01-01

    Using a model previously developed for the backscattering cross section of a planar leaf at X-band frequencies and above, the effect of leaf curvature is examined. For normal incidence on a rectangular section of a leaf curved in one and two dimensions, an integral expression for the backscattered field is evaluated numerically and by a stationary phase approximation, leading to a simple analytical expression for the cross-section reduction produced by the curvature. Numerical results based on the two methods are virtually identical, and in excellent agreement with measured data for rectangular sections of coleus leaves applied to the surfaces of styrofoam cylinders and spheres of different radii.

  12. Leaf anatomy and ultrastructure of the Crassulacean-acid-metabolism plant Kalanchoe daigremontiana.

    PubMed

    Balsamo, R A; Uribe, E G

    1988-02-01

    Light-microscopic analysis of leaf clearings of the obligate Crassulacean-acid-metabolism (CAM) species Kalanchoe daigremontiana Hamet et Perr. has shown the existence of unusual and highly irregular venation patterns. Fifth-order veins exhibit a three-dimensional random orientation with respect to the mesophyll. Minor veins were often observed crossing over or under each other and over and under major veins in the mesophyll. Paraffin sections of mature leaves show tannin cells scattered throughout the mesophyll rather evenly spaced, and a distinct layer of tannin cells below the abaxial epidermis. Scanning electron microscopy showed that bundle-sheath cells are distinct from the surrounding mesophyll in veins of all orders. Transmission electron microscopy demonstrated developing sieve-tube elements in expanded leaves. Cytosolic vesicles produced by dictyosomes undergo a diurnal variation in number and were often observed in association with the chloroplasts. These vesicles are an interesting feature of cell ultrastructure of CAM cells and may serve a regulatory role in the diurnal malic-acid fluctuations in this species. PMID:24226398

  13. Leaf development: a cellular perspective

    PubMed Central

    Kalve, Shweta; De Vos, Dirk; Beemster, Gerrit T. S.

    2014-01-01

    Through its photosynthetic capacity the leaf provides the basis for growth of the whole plant. In order to improve crops for higher productivity and resistance for future climate scenarios, it is important to obtain a mechanistic understanding of leaf growth and development and the effect of genetic and environmental factors on the process. Cells are both the basic building blocks of the leaf and the regulatory units that integrate genetic and environmental information into the developmental program. Therefore, to fundamentally understand leaf development, one needs to be able to reconstruct the developmental pathway of individual cells (and their progeny) from the stem cell niche to their final position in the mature leaf. To build the basis for such understanding, we review current knowledge on the spatial and temporal regulation mechanisms operating on cells, contributing to the formation of a leaf. We focus on the molecular networks that control exit from stem cell fate, leaf initiation, polarity, cytoplasmic growth, cell division, endoreduplication, transition between division and expansion, expansion and differentiation and their regulation by intercellular signaling molecules, including plant hormones, sugars, peptides, proteins, and microRNAs. We discuss to what extent the knowledge available in the literature is suitable to be applied in systems biology approaches to model the process of leaf growth, in order to better understand and predict leaf growth starting with the model species Arabidopsis thaliana. PMID:25132838

  14. 7 CFR 29.2528 - Leaf.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...-Cured Tobacco (u.s. Types 22, 23, and Foreign Type 96) § 29.2528 Leaf. Whole, unstemmed leaf. Leaf, when applied to tobacco in strip form, shall describe the divided unit of a whole leaf. ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf. 29.2528 Section 29.2528 Agriculture...

  15. Predicting leaf traits of herbaceous species from their spectral characteristics

    PubMed Central

    Roelofsen, Hans D; van Bodegom, Peter M; Kooistra, Lammert; Witte, Jan-Philip M

    2014-01-01

    Trait predictions from leaf spectral properties are mainly applied to tree species, while herbaceous systems received little attention in this topic. Whether similar trait–spectrum relations can be derived for herbaceous plants that differ strongly in growing strategy and environmental constraints is therefore unknown. We used partial least squares regression to relate key traits to leaf spectra (reflectance, transmittance, and absorbance) for 35 herbaceous species, sampled from a wide range of environmental conditions. Specific Leaf Area and nutrient-related traits (N and P content) were poorly predicted from any spectrum, although N prediction improved when expressed on a per area basis (mg/m2 leaf surface) instead of mass basis (mg/g dry matter). Leaf dry matter content was moderately to good correlated with spectra. We explain our results by the range of environmental constraints encountered by herbaceous species; both N and P limitations as well as a range of light and water availabilities occurred. This weakened the relation between the measured response traits and the leaf constituents that are truly responsible for leaf spectral behavior. Indeed, N predictions improve considering solely upper or under canopy species. Therefore, trait predictions in herbaceous systems should focus on traits relating to dry matter content and the true, underlying drivers of spectral properties. PMID:24683454

  16. Effects of leaf age within growth stages of pepper and sorghum plants on leaf thickness, water, chlorophyll, and light reflectance. [in spectral vegetation discrimination

    NASA Technical Reports Server (NTRS)

    Gausman, H. W.; Cardenas, R.; Berumen, A.

    1974-01-01

    Pepper and sorghum plants (characterized by porous and compact leaf mesophylls, respectively) were used to study the influence of leaf age on light reflectance. Measurements were limited to the upper five nodal positions within each growth stage, since upper leaves make up most of the reflectance surfaces remotely sensed. The increase in leaf thickness and water content with increasing leaf age was taken into consideration, since each of these factors affects the reflectance as well as the selection of spectral wavelength intervals for optimum discrimination of vegetation.

  17. Exserohilum Leaf Spot on Tigergrass

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Tigergrass (Thysanolaena maxima (Roxb.) Kuntze ) is a popular ornamental grass grown throughout landscapes in South Florida. In the summer of 2006, a leaf spot was observed on tigergrass in the landscape and a commercial nursery in Homestead, FL. The causal agent of the leaf spot was isolated, cha...

  18. How to pattern a leaf

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Leaf development presents a tremendous resource for tackling the question of patterning in biology. Leaves can be simple or highly dissected. They may have elaborated parts such as the tendrils of a pea leaf or the rolled blade of a carnivorous pitcher plant. Despite the variation in size, shape, an...

  19. A Simplified GIS Approach to Modeling Global Leaf Water Isoscapes

    PubMed Central

    West, Jason B.; Sobek, Adam; Ehleringer, James R.

    2008-01-01

    The stable hydrogen (δ2H) and oxygen (δ18O) isotope ratios of organic and inorganic materials record biological and physical processes through the effects of substrate isotopic composition and fractionations that occur as reactions proceed. At large scales, these processes can exhibit spatial predictability because of the effects of coherent climatic patterns over the Earth's surface. Attempts to model spatial variation in the stable isotope ratios of water have been made for decades. Leaf water has a particular importance for some applications, including plant organic materials that record spatial and temporal climate variability and that may be a source of food for migrating animals. It is also an important source of the variability in the isotopic composition of atmospheric gases. Although efforts to model global-scale leaf water isotope ratio spatial variation have been made (especially of δ18O), significant uncertainty remains in models and their execution across spatial domains. We introduce here a Geographic Information System (GIS) approach to the generation of global, spatially-explicit isotope landscapes ( = isoscapes) of “climate normal” leaf water isotope ratios. We evaluate the approach and the resulting products by comparison with simulation model outputs and point measurements, where obtainable, over the Earth's surface. The isoscapes were generated using biophysical models of isotope fractionation and spatially continuous precipitation isotope and climate layers as input model drivers. Leaf water δ18O isoscapes produced here generally agreed with latitudinal averages from GCM/biophysical model products, as well as mean values from point measurements. These results show global-scale spatial coherence in leaf water isotope ratios, similar to that observed for precipitation and validate the GIS approach to modeling leaf water isotopes. These results demonstrate that relatively simple models of leaf water enrichment combined with spatially

  20. Leaf hydraulics II: vascularized tissues.

    PubMed

    Rockwell, Fulton E; Holbrook, N Michele; Stroock, Abraham D

    2014-01-01

    Current models of leaf hydration employ an Ohm's law analogy of the leaf as an ideal capacitor, neglecting the resistance to flow between cells, or treat the leaf as a plane sheet with a source of water at fixed potential filling the mid-plane, neglecting the discrete placement of veins as well as their resistance. We develop a model of leaf hydration that considers the average conductance of the vascular network to a representative areole (region bounded by the vascular network), and represent the volume of tissue within the areole as a poroelastic composite of cells and air spaces. Solutions to the 3D flow problem are found by numerical simulation, and these results are then compared to 1D models with exact solutions for a range of leaf geometries, based on a survey of temperate woody plants. We then show that the hydration times given by these solutions are well approximated by a sum of the ideal capacitor and plane sheet times, representing the time for transport through the vasculature and tissue respectively. We then develop scaling factors relating this approximate solution to the 3D model, and examine the dependence of these scaling factors on leaf geometry. Finally, we apply a similar strategy to reduce the dimensions of the steady state problem, in the context of peristomatal transpiration, and consider the relation of transpirational gradients to equilibrium leaf water potential measurements. PMID:24012489

  1. Leaf Relative Water Content Estimated from Leaf Reflectance and Transmittance

    NASA Technical Reports Server (NTRS)

    Vanderbilt, Vern; Daughtry, Craig; Dahlgren, Robert

    2016-01-01

    Remotely sensing the water status of plants and the water content of canopies remain long term goals of remote sensing research. In the research we report here, we used optical polarization techniques to monitor the light reflected from the leaf interior, R, as well as the leaf transmittance, T, as the relative water content (RWC) of corn (Zea mays) leaves decreased. Our results show that R and T both change nonlinearly. The result show that the nonlinearities cancel in the ratio R/T, which appears linearly related to RWC for RWC less than 90%. The results suggest that potentially leaf water status and perhaps even canopy water status could be monitored starting from leaf and canopy optical measurements.

  2. Regulation of Compound Leaf Development

    PubMed Central

    Wang, Yuan; Chen, Rujin

    2013-01-01

    Leaf morphology is one of the most variable, yet inheritable, traits in the plant kingdom. How plants develop a variety of forms and shapes is a major biological question. Here, we discuss some recent progress in understanding the development of compound or dissected leaves in model species, such as tomato (Solanum lycopersicum), Cardamine hirsuta and Medicago truncatula, with an emphasis on recent discoveries in legumes. We also discuss progress in gene regulations and hormonal actions in compound leaf development. These studies facilitate our understanding of the underlying regulatory mechanisms and put forward a prospective in compound leaf studies. PMID:27135488

  3. Leaf domatia mediate mutualism between mites and a tropical tree.

    PubMed

    Romero, Gustavo Q; Benson, Woodruff W

    2004-08-01

    Although associations between mites and leaf domatia have been widely reported, their consequences for plants, especially for natural tree populations, particularly in the tropics, are largely unknown. In experiments with paired Cupania vernalis (Sapindaceae) saplings in a semi-deciduous forest in south-east Brazil, we blocked leaf domatia to examine their effect: (1) on mites and other arthropods, and (2) on damage caused by fungi and herbivorous arthropods. In general, plants with resin-blocked domatia had fewer predaceous mites on leaves than control plants with unaltered domatia, but the total abundances of fungivorous and of phytophagous mites remained unchanged. However, phytophagous eriophyid mites, the most numerous inhabitants of domatia, decreased on leaf surfaces with the blocking treatment. In a second experiment, treated plants lacking functional domatia developed significantly greater numbers and areas of chlorosis, apparently due to increased eriophyid attacks, whereas fungal attack, epiphyll abundance and leaf-area loss were unaffected. This seems to be the first experimental study to demonstrate that leaf domatia can benefit plants against herbivory in a natural system. The possible stabilizing effect of leaf domatia on predator-prey interactions is discussed. PMID:15205936

  4. 7 CFR 29.3525 - Leaf.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... Type 95) § 29.3525 Leaf. Whole, unstemmed leaf. Leaf, when applied to tobacco in strip form, shall... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf. 29.3525 Section 29.3525 Agriculture Regulations... Practices), DEPARTMENT OF AGRICULTURE COMMODITY STANDARDS AND STANDARD CONTAINER REGULATIONS...

  5. 7 CFR 29.1028 - Leaf.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... Type 92) § 29.1028 Leaf. Whole, unstemmed leaf. Leaf, when applied to tobacco in strip form, shall... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf. 29.1028 Section 29.1028 Agriculture Regulations... Practices), DEPARTMENT OF AGRICULTURE COMMODITY STANDARDS AND STANDARD CONTAINER REGULATIONS...

  6. 7 CFR 29.3033 - Leaf.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... Leaf. Whole, unstemmed leaf. Leaf, when applied to tobacco in strip form, shall describe the divided... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf. 29.3033 Section 29.3033 Agriculture Regulations... Practices), DEPARTMENT OF AGRICULTURE COMMODITY STANDARDS AND STANDARD CONTAINER REGULATIONS...

  7. Near infrared leaf reflectance modeling

    NASA Technical Reports Server (NTRS)

    Parrish, J. B.

    1985-01-01

    Near infrared leaf reflectance modeling using Fresnel's equation (Kumar and Silva, 1973) and Snell's Law successfully approximated the spectral curve for a 0.25-mm turgid oak leaf lying on a Halon background. Calculations were made for ten interfaces, air-wax, wax-cellulose, cellulose-water, cellulose-air, air-water, and their inverses. A water path of 0.5 mm yielded acceptable results, and it was found that assignment of more weight to those interfaces involving air versus water or cellulose, and less to those involving wax, decreased the standard deviation of the error for all wavelengths. Data suggest that the air-cell interface is not the only important contributor to the overall reflectance of a leaf. Results also argue against the assertion that the near infrared plateau is a function of cell structure within the leaf.

  8. Increasing leaf hydraulic conductance with transpiration rate minimizes the water potential drawdown from stem to leaf

    PubMed Central

    Simonin, Kevin A.; Burns, Emily; Choat, Brendan; Barbour, Margaret M.; Dawson, Todd E.; Franks, Peter J.

    2015-01-01

    Leaf hydraulic conductance (k leaf) is a central element in the regulation of leaf water balance but the properties of k leaf remain uncertain. Here, the evidence for the following two models for k leaf in well-hydrated plants is evaluated: (i) k leaf is constant or (ii) k leaf increases as transpiration rate (E) increases. The difference between stem and leaf water potential (ΔΨstem–leaf), stomatal conductance (g s), k leaf, and E over a diurnal cycle for three angiosperm and gymnosperm tree species growing in a common garden, and for Helianthus annuus plants grown under sub-ambient, ambient, and elevated atmospheric CO2 concentration were evaluated. Results show that for well-watered plants k leaf is positively dependent on E. Here, this property is termed the dynamic conductance, k leaf(E), which incorporates the inherent k leaf at zero E, which is distinguished as the static conductance, k leaf(0). Growth under different CO2 concentrations maintained the same relationship between k leaf and E, resulting in similar k leaf(0), while operating along different regions of the curve owing to the influence of CO2 on g s. The positive relationship between k leaf and E minimized variation in ΔΨstem–leaf. This enables leaves to minimize variation in Ψleaf and maximize g s and CO2 assimilation rate over the diurnal course of evaporative demand. PMID:25547915

  9. Increasing leaf hydraulic conductance with transpiration rate minimizes the water potential drawdown from stem to leaf.

    PubMed

    Simonin, Kevin A; Burns, Emily; Choat, Brendan; Barbour, Margaret M; Dawson, Todd E; Franks, Peter J

    2015-03-01

    Leaf hydraulic conductance (k leaf) is a central element in the regulation of leaf water balance but the properties of k leaf remain uncertain. Here, the evidence for the following two models for k leaf in well-hydrated plants is evaluated: (i) k leaf is constant or (ii) k leaf increases as transpiration rate (E) increases. The difference between stem and leaf water potential (ΔΨstem-leaf), stomatal conductance (g s), k leaf, and E over a diurnal cycle for three angiosperm and gymnosperm tree species growing in a common garden, and for Helianthus annuus plants grown under sub-ambient, ambient, and elevated atmospheric CO₂ concentration were evaluated. Results show that for well-watered plants k leaf is positively dependent on E. Here, this property is termed the dynamic conductance, k leaf(E), which incorporates the inherent k leaf at zero E, which is distinguished as the static conductance, k leaf(0). Growth under different CO₂ concentrations maintained the same relationship between k leaf and E, resulting in similar k leaf(0), while operating along different regions of the curve owing to the influence of CO₂ on g s. The positive relationship between k leaf and E minimized variation in ΔΨstem-leaf. This enables leaves to minimize variation in Ψleaf and maximize g s and CO₂ assimilation rate over the diurnal course of evaporative demand. PMID:25547915

  10. Interaction between Silver Nanoparticles and Spinach Leaf

    NASA Astrophysics Data System (ADS)

    Tian, Y.; Li, H.; Zhang, Y.; Riser, E.; He, S.; Zhang, W.

    2013-12-01

    Interactions of engineered nanoparticles (ENPs) with plant surfaces are critical to assessing the bioavailability of ENPs to edible plants and to further evaluating impacts of ENPs on ecological health and food safety. Silver nanoparticles (i.e., nanoAg) could enter the agroecosystems either as an active ingredient in pesticides or from other industrial and consumer applications. Thus, in the events of pesticide application, rainfall, and irrigation, vegetable leaves could become in contact and then interact with nanoAg. The present study was to assess whether the interaction of nanoAg with spinach leaves can be described by classical sorption models and to what extent it depends on and varies with dispersion methods, environmental temperature, and ion release. We investigated the stability and ion release of nanoAg dispersed by sodium dodecyl sulfate (SDS, 1%) and humic acid (HA, 10 mg C/L) solutions, as well as sorption and desorption of nanoAg on and from the fresh spinach leaf. Results showed SDS-nanoAg released about 2%-8% more Ag ion than HA-nanoAg. The sorption of Ag ion, described by the Freundlich model in the initial concentration range of 0.6-50 mg/L, was 2-4 times higher than that of nanoAg. The sorption of nanoAg on spinach leaf can be fitted by the Langmuir model, and the maximum sorption amount of HA-nanoAg and SDS-nanoAg was 0.21 and 0.41 mg/g, respectively. The higher sorption of SDS-nanoAg relative to that of HA-nanoAg could be partially resulted from the higher release of Ag ion from the former. The maximum desorption amount of HA-nanoAg and SDS-nanoAg in 1% SDS solution was 0.08 and 0.10 mg/g, respectively. NanoAg attachment on and its penetration to the spinach leaf was visualized by the Scanning Electron Microscope equipped with an Energy Dispersive Spectrometer (SEM-EDS). It is equally important that the less sorption of nanoAg under low environmental temperature could be partially due to the closure of stomata, as verified by SEM-EDS. Cyto

  11. Throughfall Drop Size Distribution in relation to Leaf Canopy State

    NASA Astrophysics Data System (ADS)

    Hudson, S.; Nanko, K.; Levia, D. F., Jr.

    2014-12-01

    The partitioning of incident precipitation by a forest canopy into throughfall and stemflow varies as a function of meteorological conditions, tree species, leaf morphology and surface roughness. Little work quantified the throughfall drop size signature of precipitation events relative to changes in leaf canopy state of deciduous forests. This is the first study to compare throughfall drop size distributions in the presence and absence of foliage. To quantify individual throughfall drops, a laser disdrometer gauge was deployed below an observed drip point under a Liriodendron tulipifera L. (yellow poplar) tree, in northeastern Maryland, USA. More than 750,000 individual throughfall droplets have been counted and measured from precipitation events generating more than 5 mm gross rainfall over a period of 12 months. Throughfall during leafless events had significantly larger maximum drop diameters (6.74mm leafless, 5.55mm leafed) and median volume diameter of drops (5.44mm leafless, 3.31mm leafed) than throughfall generated when leaves were present. Statistical techniques have demonstrated the substantial influence of canopy state over the drop size spectra. Principal component analysis and factor analysis both resulted in canopy state loading positively with increases in maximum drop diameter while loading negatively with air temperature. Boosted regression trees analysis corroborated these findings. Our findings correspond with the physical conditions of a leafless canopy, and illustrated the greater extent of surface adhesion of intercepted water films on woody surfaces as opposed to foliar surfaces, thereby underscoring the importance of canopy state on throughfall inputs.

  12. Functional relationships of leafing intensity to plant height, growth form and leaf habit

    NASA Astrophysics Data System (ADS)

    Yan, En-Rong; Milla, Rubén; Aarssen, Lonnie W.; Wang, Xi-Hua

    2012-05-01

    Leafing intensity, i.e. the number of leaves per unit of stem volume or mass, is a common developmental correlate of leaf size. However, the ecological significance and the functional implications of variation in leafing intensity, other than its relation to leaf size, are unknown. Here, we explore its relationships with plant height, growth form, leaf size, and leaf habit to test a series of corollaries derived from the leafing intensity premium hypothesis. Volume-based leafing intensities and plant heights were recorded for 109 woody species from the subtropical evergreen broadleaf forests of eastern China. In addition, we compiled leafing intensity data from published literature, and combined it with our data to form a 398 species dataset, to test for differences of leafing intensity between plant growth forms (i.e. herbaceous and woody) and leaf habits (i.e. deciduous and evergreens). Leafing intensity was negatively correlated with plant height and individual leaf mass. Volume-based leafing intensities were significantly higher in herbaceous species than in woody species, and also higher in deciduous than in evergreen woody species. In conclusion, leafing intensity relates strongly to plant height, growth form, leaf size, and leaf habit in directions generally in accordance to the leafing intensity premium hypothesis. These results can be interpreted in terms of the evolution of adaptive strategies involving response to herbivory, competitive ability for light and reproductive economy.

  13. How to pattern a leaf.

    PubMed

    Bolduc, N; O'Connor, D; Moon, J; Lewis, M; Hake, S

    2012-01-01

    Leaf development presents a tremendous resource for tackling the question of patterning in biology. Leaves can be simple or highly dissected. They may have elaborated parts such as the tendrils of a pea leaf or the rolled blade of a carnivorous pitcher plant. Despite the variation in size, shape, and function, all leaves initiate in the same manner: from the flanks of a meristem. The maize leaf is useful for analysis of patterning due to the wealth of mutants and the distinct tissues along the proximal distal axis. The blade is distal, the sheath is proximal, and the ligule forms at the blade/sheath boundary. Establishment of this boundary involves the transcription factors LIGULELESS1 and LIGULELESS2 and the kinase LIGULELESS NARROW. The meristem-specific protein KNOTTED1 (KN1) binds and modulates the lg2 gene. Given the localization of KN1 at the proximal end of the leaf from the time of inception, we hypothesize that KN1 has a role in establishing the very proximal end of the leaf, whereas an auxin maximum guides the growing distal tip. PMID:23174765

  14. MODIS Measures Total U.S. Leaf Area

    NASA Technical Reports Server (NTRS)

    2002-01-01

    This composite image over the continental United States was produced with data acquired by the Moderate-resolution Imaging Spectroradiometer (MODIS) during the period March 24 - April 8, 2000. The image is a map of the density of the plant canopy covering the ground. It is the first in a series of images over the continental U.S. produced by the MODIS Land Discipline Group (refer to this site June 2 and 5 for the next two images in the series). The image is a MODIS data product called 'Leaf Area Index,' which is produced by radiometrically measuring the visible and near infrared energy reflected by vegetation. The Leaf Area Index provides information on the structure of plant canopy, showing how much surface area is covered by green foliage relative to total land surface area. In this image, dark green pixels indicate areas where more than 80 percent of the land surface is covered by green vegetation, light green pixels show where leaves cover about 10 to 50 percent of the land surface, and brown pixels show virtually no leaf coverage. The more leaf area a plant has, the more sunlight it can absorb for photosynthesis. Leaf Area Index is one of a new suite of measurements that scientists use to understand how the Earth's land surfaces are changing over time. Their goal is to use these measurements to refine computer models well enough to simulate how the land biosphere influences the natural cycles of water, carbon, and energy throughout the Earth system. This image is the first of its kind from the MODIS instrument, which launched in December 1999 aboard the Terra spacecraft. MODIS began acquiring scientific data on February 24, 2000, when it first opened its aperture door. The MODIS instrument and Terra spacecraft are both managed by NASA's Goddard Space Flight Center, Greenbelt, MD. Image courtesy Steven Running, MODIS Land Group Member, University of Montana

  15. Evaluation of leaf removal as a means to reduce nutrient concentrations and loads in urban stormwater.

    PubMed

    Selbig, William R

    2016-11-15

    While the sources of nutrients to urban stormwater are many, the primary contributor is often organic detritus, especially in areas with dense overhead tree canopy. One way to remove organic detritus before it becomes entrained in runoff is to implement a city-wide leaf collection and street cleaning program. Improving our knowledge of the potential reduction of nutrients to stormwater through removal of leaves and other organic detritus on streets could help tailor more targeted municipal leaf collection programs. This study characterized an upper ideal limit in reductions of total and dissolved forms of phosphorus and nitrogen in stormwater through implementation of a municipal leaf collection and street cleaning program in Madison, WI, USA. Additional measures were taken to remove leaf litter from street surfaces prior to precipitation events. Loads of total and dissolved phosphorus were reduced by 84 and 83% (p<0.05), and total and dissolved nitrogen by 74 and 71% (p<0.05) with an active leaf removal program. Without leaf removal, 56% of the annual total phosphorus yield (winter excluded) was due to leaf litter in the fall compared to 16% with leaf removal. Despite significant reductions in load, total nitrogen showed only minor changes in fall yields without and with leaf removal at 19 and 16%, respectively. The majority of nutrient concentrations were in the dissolved fraction making source control through leaf removal one of the few treatment options available to environmental managers when reducing the amount of dissolved nutrients in stormwater runoff. Subsequently, the efficiency, frequency, and timing of leaf removal and street cleaning are the primary factors to consider when developing a leaf management program. PMID:27470671

  16. Leaf hydraulic conductance for a tank bromeliad: axial and radial pathways for moving and conserving water.

    PubMed

    North, Gretchen B; Lynch, Frank H; Maharaj, Franklin D R; Phillips, Carly A; Woodside, Walter T

    2013-01-01

    Epiphytic plants in the Bromeliaceae known as tank bromeliads essentially lack stems and absorptive roots and instead take up water from reservoirs formed by their overlapping leaf bases. For such plants, leaf hydraulic conductance is plant hydraulic conductance. Their simple strap-shaped leaves and parallel venation make them suitable for modeling leaf hydraulic conductance based on vasculature and other anatomical and morphological traits. Plants of the tank bromeliad Guzmania lingulata were investigated in a lowland tropical forest in Costa Rica and a shaded glasshouse in Los Angeles, CA, USA. Stomatal conductance to water vapor and leaf anatomical variables related to hydraulic conductance were measured for both groups. Tracheid diameters and numbers of vascular bundles (veins) were used with the Hagen-Poiseuille equation to calculate axial hydraulic conductance. Measurements of leaf hydraulic conductance using the evaporative flux method were also made for glasshouse plants. Values for axial conductance and leaf hydraulic conductance were used in a model based on leaky cable theory to estimate the conductance of the radial pathway from the vein to the leaf surface and to assess the relative contributions of both axial and radial pathways. In keeping with low stomatal conductance, low stomatal density, low vein density, and narrow tracheid diameters, leaf hydraulic conductance for G. lingulata was quite low in comparison with most other angiosperms. Using the predicted axial conductance in the leaky cable model, the radial resistance across the leaf mesophyll was predicted to predominate; lower, more realistic values of axial conductance resulted in predicted radial resistances that were closer to axial resistance in their impact on total leaf resistance. Tracer dyes suggested that water uptake through the tank region of the leaf was not limiting. Both dye movement and the leaky cable model indicated that the leaf blade of G. lingulata was structurally and

  17. The Influence of Source Biases on Sedimentary Leaf Waxes and Their Stable Isotope Compositions

    NASA Astrophysics Data System (ADS)

    Diefendorf, A. F.; Freimuth, E. J.; Lowell, T. V.; Wiles, G. C.

    2015-12-01

    Leaf waxes and their carbon (δ13C) and hydrogen (δD) isotopic compositions are an important tool to understand past changes in paleoclimate and paleovegetation. Important recent advances in our understanding about the isotopic signal preserved in sedimentary leaf waxes have been inferred from studies made on individual modern plants. However, paleoreconstructions are based on sedimentary leaf waxes, which reflect mixing between multiple sources, such as ablated leaf waxes from nearby or from afar, wind blown leaf litter, and riverine transported leaf waxes. Each of these sources integrates leaf waxes from different species and growth forms, likely resulting in source-specific taphonomic biases on sedimentary leaf wax isotopes. To better understand source biases in sedimentary leaf waxes, we investigated n-alkanes and n-alkanoic acids and their carbon and hydrogen isotopes in vegetation and lake sediments at Brown's Lake and Bog, a 'simple' forested closed-basin lake in northeastern Ohio. Interestingly, we found that tree n-alkane δD varied substantially during the growing season, broadly tracking changes in source water composition. However, δD values of n-alkanes in the tree leaf litter did not match that of the most recent sedimentary n-alkanes. Instead, surface sediment n-alkane δD more closely matched that of the woody shrubs and grasses growing right around the lake. n-Alkanoic acid data is forthcoming. We are currently exploring lake sediment n-alkane accumulation rates against midwestern flux rates of wind blown leaf waxes from afar. Our preliminary results suggest that although studies made on individual leaves are indeed important, we may need to consider additional leaf wax sources that potentially influence sedimentary archives.

  18. Linkage between canopy water storage and drop size distributions of leaf drips

    NASA Astrophysics Data System (ADS)

    Nanko, Kazuki; Watanabe, Ai; Hotta, Norifumi; Suzuki, Masakazu

    2013-04-01

    Differences in drop size distribution (DSD) of leaf drips among tree species have been estimated and physically interpreted to clarify the leaf drip generation process. Leaf drip generation experiments for nine species were conducted in an indoor location without foliage vibration using an automatic mist spray. Broad-leaved species produced a similar DSD among species whose leaves had a matte surface and a second similar DSD among species whose leaves had a coated surface. The matte broad leaves produced a larger and wider range of DSDs than the coated broad leaves. Coated coniferous needles had a wider range of DSDs than the coated broad leaves and different DSDs were observed for different species. The species with shorter dense needles generated a larger DSD. The leaf drip diameter was calculated through the estimation of a state of equilibrium of a hanging drop on the leaves based on physical theory. The calculations indicated that the maximum diameter of leaf drips was determined by the contact angle, and the range of DSDs was determined by the variation in contact length and the contact diameter at the hanging points. The results revealed that leaf drip DSD changed due to variations in leaf hydrophobicity, leaf roughness, leaf geometry and leaf inclination among the different tree species. This study allows the modelization of throughfall DSD. Furthermore, it indicates the possibility of interpreting canopy water processes from canopy water storage to drainage through the contact angle and leaf drip DSD. The part of this study is published in Nanko et al. (2013, Agric. Forest. Meteorol. 169, 74-84).

  19. Unified changes in cell size permit coordinated leaf evolution.

    PubMed

    Brodribb, Tim J; Jordan, Greg J; Carpenter, Raymond J

    2013-07-01

    The processes by which the functions of interdependent tissues are coordinated as lineages diversify are poorly understood. Here, we examine evolutionary coordination of vascular, epidermal and cortical leaf tissues in the anatomically, ecologically and morphologically diverse woody plant family Proteaceae. We found that, across the phylogenetic range of Proteaceae, the sizes of guard, epidermal, palisade and xylem cells were positively correlated with each other but negatively associated with vein and stomatal densities. The link between venation and stomata resulted in a highly efficient match between potential maximum water loss (determined by stomatal conductance) and the leaf vascular system's capacity to replace that water. This important linkage is likely to be driven by stomatal size, because spatial limits in the packing of stomata onto the leaf surface apparently constrain the maximum size and density of stomata. We conclude that unified evolutionary changes in cell sizes of independent tissues, possibly mediated by changes in genome size, provide a means of substantially modifying leaf function while maintaining important functional links between leaf tissues. Our data also imply the presence of alternative evolutionary strategies involving cellular miniaturization during radiation into closed forest, and cell size increase in open habitats. PMID:23647069

  20. Global variability in leaf respiration in relation to climate, plant functional types and leaf traits.

    PubMed

    Atkin, Owen K; Bloomfield, Keith J; Reich, Peter B; Tjoelker, Mark G; Asner, Gregory P; Bonal, Damien; Bönisch, Gerhard; Bradford, Matt G; Cernusak, Lucas A; Cosio, Eric G; Creek, Danielle; Crous, Kristine Y; Domingues, Tomas F; Dukes, Jeffrey S; Egerton, John J G; Evans, John R; Farquhar, Graham D; Fyllas, Nikolaos M; Gauthier, Paul P G; Gloor, Emanuel; Gimeno, Teresa E; Griffin, Kevin L; Guerrieri, Rossella; Heskel, Mary A; Huntingford, Chris; Ishida, Françoise Yoko; Kattge, Jens; Lambers, Hans; Liddell, Michael J; Lloyd, Jon; Lusk, Christopher H; Martin, Roberta E; Maksimov, Ayal P; Maximov, Trofim C; Malhi, Yadvinder; Medlyn, Belinda E; Meir, Patrick; Mercado, Lina M; Mirotchnick, Nicholas; Ng, Desmond; Niinemets, Ülo; O'Sullivan, Odhran S; Phillips, Oliver L; Poorter, Lourens; Poot, Pieter; Prentice, I Colin; Salinas, Norma; Rowland, Lucy M; Ryan, Michael G; Sitch, Stephen; Slot, Martijn; Smith, Nicholas G; Turnbull, Matthew H; VanderWel, Mark C; Valladares, Fernando; Veneklaas, Erik J; Weerasinghe, Lasantha K; Wirth, Christian; Wright, Ian J; Wythers, Kirk R; Xiang, Jen; Xiang, Shuang; Zaragoza-Castells, Joana

    2015-04-01

    Leaf dark respiration (Rdark ) is an important yet poorly quantified component of the global carbon cycle. Given this, we analyzed a new global database of Rdark and associated leaf traits. Data for 899 species were compiled from 100 sites (from the Arctic to the tropics). Several woody and nonwoody plant functional types (PFTs) were represented. Mixed-effects models were used to disentangle sources of variation in Rdark . Area-based Rdark at the prevailing average daily growth temperature (T) of each site increased only twofold from the Arctic to the tropics, despite a 20°C increase in growing T (8-28°C). By contrast, Rdark at a standard T (25°C, Rdark (25) ) was threefold higher in the Arctic than in the tropics, and twofold higher at arid than at mesic sites. Species and PFTs at cold sites exhibited higher Rdark (25) at a given photosynthetic capacity (Vcmax (25) ) or leaf nitrogen concentration ([N]) than species at warmer sites. Rdark (25) values at any given Vcmax (25) or [N] were higher in herbs than in woody plants. The results highlight variation in Rdark among species and across global gradients in T and aridity. In addition to their ecological significance, the results provide a framework for improving representation of Rdark in terrestrial biosphere models (TBMs) and associated land-surface components of Earth system models (ESMs). PMID:25581061

  1. Assimilation of satellite reflecance dataa into a dynamical leaf model to infer seasonally varying leaf area for climate and carbon models

    SciTech Connect

    Liu, Qing; Gu, Lianhong; Dickinson, Robert E.; Tian, Y; Zhou, L; Post, Wilfred M

    2007-01-01

    Leaf area index is an important input for many climate and carbon models. The widely used leaf area products derived from satellite-observed surface reflectances contain substantial erratic fluctuations in time due to inadequate atmospheric corrections and observational and retrieval uncertainties. These fluctuations are inconsistent with the seasonal dynamics of leaf area, known to be gradual. Their use in process-based terrestrial carbon models corrupts model behavior, making diagnosis of model performance difficult. We propose a data assimilation approach that combines the satellite observations of Moderate Resolution Imaging Spectroradiometer (MODIS) albedo with a dynamical leaf model. Its novelty is that the seasonal cycle of the directly retrieved leaf areas is smooth and consistent with both observations and current understandings of processes controlling leaf area dynamics. The approach optimizes the dynamical model parameters such that the difference between the estimated surface reflectances based on the modeled leaf area and those of satellite observations is minimized. We demonstrate the usefulness and advantage of our new approach at multiple deciduous forest sites in the United States.

  2. Differences on photosynthetic limitations between leaf margins and leaf centers under potassium deficiency for Brassica napus L.

    PubMed Central

    Lu, Zhifeng; Ren, Tao; Pan, Yonghui; Li, Xiaokun; Cong, Rihuan; Lu, Jianwei

    2016-01-01

    Analyzing the proportions of stomatal (SL), mesophyll conductance (MCL) and biochemical limitations (BL) imposed by potassium (K) deficit, and evaluating their relationships to leaf K status will be helpful to understand the mechanism underlying the inhibition of K deficiency on photosynthesis (A). A quantitative limitation analysis of K deficiency on photosynthesis was performed on leaf margins and centers under K deficiency and sufficient K supply treatments of Brassica napus L. Potassium deficiency decreased A, stomatal (gs) and mesophyll conductance (gm) of margins, SL, MCL and BL accounted for 23.9%, 33.0% and 43.1% of the total limitations. While for leaf centers, relatively low limitations occurred. Nonlinear curve fitting analysis indicated that each limiting factor generated at same leaf K status (1.07%). Although MCL was the main component of limitations when A began to fall, BL replaced it at a leaf K concentration below 0.78%. Up-regulated MCL was related to lower surface area of chloroplasts exposed to intercellular airspaces (Sc/S) and larger cytosol diffusion resistance but not the cell wall thickness. Our results highlighted that photosynthetic limitations appear simultaneously under K deficiency and vary with increasing K deficiency intensity. PMID:26902263

  3. Leaf morphophysiology of a Neotropical mistletoe is shaped by seasonal patterns of host leaf phenology.

    PubMed

    Scalon, Marina Corrêa; Rossatto, Davi Rodrigo; Domingos, Fabricius Maia Chaves Bicalho; Franco, Augusto Cesar

    2016-04-01

    Several mistletoe species are able to grow and reproduce on both deciduous and evergreen hosts, suggesting a degree of plasticity in their ability to cope with differences in intrinsic host functions. The aim of this study was to investigate the influence of host phenology on mistletoe water relations and leaf gas exchange. Mistletoe Passovia ovata parasitizing evergreen (Miconia albicans) hosts and P. ovata parasitizing deciduous (Byrsonima verbascifolia) hosts were sampled in a Neotropical savanna. Photosynthetic parameters, diurnal cycles of stomatal conductance, pre-dawn and midday leaf water potential, and stomatal anatomical traits were measured during the peak of the dry and wet seasons, respectively. P. ovata showed distinct water-use strategies that were dependent on host phenology. For P. ovata parasitizing the deciduous host, water use efficiency (WUE; ratio of photosynthetic rate to transpirational water loss) was 2-fold lower in the dry season than in the wet season; in contrast, WUE was maintained at the same level during the wet and dry seasons in P. ovata parasitizing the evergreen host. Generally, mistletoe and host diurnal cycles of stomatal conductance were linked, although there were clear differences in leaf water potential, with mistletoe showing anisohydric behaviour and the host showing isohydric behaviour. Compared to mistletoes attached to evergreen hosts, those parasitizing deciduous hosts had a 1.4-fold lower stomatal density and 1.2-fold wider stomata on both leaf surfaces, suggesting that the latter suffered less intense drought stress. This is the first study to show morphophysiological differences in the same mistletoe species parasitizing hosts of different phenological groups. Our results provide evidence that phenotypical plasticity (anatomical and physiological) might be essential to favour the use of a greater range of hosts. PMID:26686200

  4. Comparative Infectivity of Cronartium ribicola Aeciospores and Urediniospores in Genotypes of Ribes nigrum

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Hosts for the fungus Cronartium ribicola, causal agent of white pine blister rust (WPBR), include five-needle pines, currants, and gooseberries. Aeciospores, produced from cankers on diseased pines, and urediniospores, originating from uredinia on abaxial leaf surfaces of susceptible Ribes, can ...

  5. Pseudomonas blight caused by Pseudomonas syringae on raspberry in California

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Plantings of red raspberry (Rubus idaeus var. strigosus) exhibited symptoms of a previously undocumented disease. Lesions were observable from both adaxial and abaxial leaf surfaces. As disease progressed, lesions enlarged and coalesced, resulting in significant dark brown to black blighting of the ...

  6. Behavior of Leaf Meristems and Their Modification

    PubMed Central

    Ichihashi, Yasunori; Tsukaya, Hirokazu

    2015-01-01

    A major source of diversity in flowering plant form is the extensive variability of leaf shape and size. Leaf formation is initiated by recruitment of a handful of cells flanking the shoot apical meristem (SAM) to develop into a complex three-dimensional structure. Leaf organogenesis depends on activities of several distinct meristems that are established and spatiotemporally differentiated after the initiation of leaf primordia. Here, we review recent findings in the gene regulatory networks that orchestrate leaf meristem activities in a model plant Arabidopsis thaliana. We then discuss recent key studies investigating the natural variation in leaf morphology to understand how the gene regulatory networks modulate leaf meristems to yield a substantial diversity of leaf forms during the course of evolution. PMID:26648955

  7. Relationships between sugarcane leaf hyperspectral reflectance, leaf nitrogen content, and yield components

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Leaf spectral reflectance has been used to estimate crop leaf chemical composition and other physiological characters. Leaf reflectance of sugarcane (Saccharum spp.) may be of use in evaluating genotypes. The objectives of this study were: (1) to identify sugarcane genotypic variation in leaf hypers...

  8. Analysis of Circadian Leaf Movements.

    PubMed

    Müller, Niels A; Jiménez-Gómez, José M

    2016-01-01

    The circadian clock is a molecular timekeeper that controls a wide variety of biological processes. In plants, clock outputs range from the molecular level, with rhythmic gene expression and metabolite content, to physiological processes such as stomatal conductance or leaf movements. Any of these outputs can be used as markers to monitor the state of the circadian clock. In the model plant Arabidopsis thaliana, much of the current knowledge about the clock has been gained from time course experiments profiling expression of endogenous genes or reporter constructs regulated by the circadian clock. Since these methods require labor-intensive sample preparation or transformation, monitoring leaf movements is an interesting alternative, especially in non-model species and for natural variation studies. Technological improvements both in digital photography and image analysis allow cheap and easy monitoring of circadian leaf movements. In this chapter we present a protocol that uses an autonomous point and shoot camera and free software to monitor circadian leaf movements in tomato. PMID:26867616

  9. Exobasidium leaf and fruit spot

    Technology Transfer Automated Retrieval System (TEKTRAN)

    During the past five or so years blueberry growers in south Mississippi have discovered the disease Exobasidium leaf and fruit spot on some of their blueberry plants. In the past this disease was considered to be of minor importance occurring infrequently on isolated farms. But in recent years it ...

  10. 7 CFR 29.6023 - Leaf structure.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf structure. 29.6023 Section 29.6023 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... INSPECTION Standards Definitions § 29.6023 Leaf structure. The cell development of a leaf as indicated by...

  11. 7 CFR 29.3035 - Leaf structure.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... Leaf structure. The cell development of a leaf as indicated by its porosity or solidity. (See Elements... 7 Agriculture 2 2011-01-01 2011-01-01 false Leaf structure. 29.3035 Section 29.3035 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  12. 7 CFR 29.6023 - Leaf structure.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... INSPECTION Standards Definitions § 29.6023 Leaf structure. The cell development of a leaf as indicated by its... 7 Agriculture 2 2012-01-01 2012-01-01 false Leaf structure. 29.6023 Section 29.6023 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  13. 7 CFR 29.1030 - Leaf structure.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... Type 92) § 29.1030 Leaf structure. The cell development of a leaf as indicated by its porosity. (See... 7 Agriculture 2 2011-01-01 2011-01-01 false Leaf structure. 29.1030 Section 29.1030 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  14. 7 CFR 29.1030 - Leaf structure.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... Type 92) § 29.1030 Leaf structure. The cell development of a leaf as indicated by its porosity. (See... 7 Agriculture 2 2013-01-01 2013-01-01 false Leaf structure. 29.1030 Section 29.1030 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  15. 7 CFR 29.6023 - Leaf structure.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... INSPECTION Standards Definitions § 29.6023 Leaf structure. The cell development of a leaf as indicated by its... 7 Agriculture 2 2011-01-01 2011-01-01 false Leaf structure. 29.6023 Section 29.6023 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  16. 7 CFR 29.3527 - Leaf structure.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... Type 95) § 29.3527 Leaf structure. The cell development of a leaf as indicated by its porosity. (See... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf structure. 29.3527 Section 29.3527 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  17. 7 CFR 29.3035 - Leaf structure.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... Leaf structure. The cell development of a leaf as indicated by its porosity or solidity. (See Elements... 7 Agriculture 2 2012-01-01 2012-01-01 false Leaf structure. 29.3035 Section 29.3035 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  18. 7 CFR 29.1030 - Leaf structure.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... Type 92) § 29.1030 Leaf structure. The cell development of a leaf as indicated by its porosity. (See... 7 Agriculture 2 2012-01-01 2012-01-01 false Leaf structure. 29.1030 Section 29.1030 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  19. 7 CFR 29.6023 - Leaf structure.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... INSPECTION Standards Definitions § 29.6023 Leaf structure. The cell development of a leaf as indicated by its... 7 Agriculture 2 2013-01-01 2013-01-01 false Leaf structure. 29.6023 Section 29.6023 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  20. 7 CFR 29.3527 - Leaf structure.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... Type 95) § 29.3527 Leaf structure. The cell development of a leaf as indicated by its porosity. (See... 7 Agriculture 2 2013-01-01 2013-01-01 false Leaf structure. 29.3527 Section 29.3527 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  1. 7 CFR 29.3035 - Leaf structure.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... Leaf structure. The cell development of a leaf as indicated by its porosity or solidity. (See Elements... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf structure. 29.3035 Section 29.3035 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  2. 7 CFR 29.3527 - Leaf structure.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... Type 95) § 29.3527 Leaf structure. The cell development of a leaf as indicated by its porosity. (See... 7 Agriculture 2 2012-01-01 2012-01-01 false Leaf structure. 29.3527 Section 29.3527 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  3. 7 CFR 29.3527 - Leaf structure.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... Type 95) § 29.3527 Leaf structure. The cell development of a leaf as indicated by its porosity. (See... 7 Agriculture 2 2011-01-01 2011-01-01 false Leaf structure. 29.3527 Section 29.3527 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  4. 7 CFR 29.3035 - Leaf structure.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... Leaf structure. The cell development of a leaf as indicated by its porosity or solidity. (See Elements... 7 Agriculture 2 2013-01-01 2013-01-01 false Leaf structure. 29.3035 Section 29.3035 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  5. 7 CFR 29.3034 - Leaf scrap.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... Leaf scrap. A by-product of unstemmed tobacco. Leaf scrap results from handling unstemmed tobacco and... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf scrap. 29.3034 Section 29.3034 Agriculture... Practices), DEPARTMENT OF AGRICULTURE COMMODITY STANDARDS AND STANDARD CONTAINER REGULATIONS...

  6. 7 CFR 29.3526 - Leaf scrap.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... Type 95) § 29.3526 Leaf scrap. A byproduct of unstemmed tobacco Leaf scrap results from handling unstemmed tobacco and consists of loose and tangled whole or broken leaves. ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf scrap. 29.3526 Section 29.3526...

  7. 7 CFR 29.2529 - Leaf scrap.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...-Cured Tobacco (u.s. Types 22, 23, and Foreign Type 96) § 29.2529 Leaf scrap. A byproduct of unstemmed tobacco. Leaf scrap results from handling unstemmed tobacco and consists of loose and tangled whole or... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf scrap. 29.2529 Section 29.2529...

  8. 7 CFR 29.6022 - Leaf scrap.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... INSPECTION Standards Definitions § 29.6022 Leaf scrap. A byproduct of unstemmed tobacco Leaf scrap results from handling unstemmed tobacco and consists of loose and tangled whole or broken leaves. ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf scrap. 29.6022 Section 29.6022...

  9. 7 CFR 29.2277 - Leaf scrap.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... INSPECTION Standards Official Standard Grades for Virginia Fire-Cured Tobacco (u.s. Type 21) § 29.2277 Leaf scrap. A byproduct of unstemmed tobacco. Leaf scrap results from handling unstemmed tobacco and consists... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf scrap. 29.2277 Section 29.2277...

  10. Comparison of half and full-leaf shape feature extraction for leaf classification

    NASA Astrophysics Data System (ADS)

    Sainin, Mohd Shamrie; Ahmad, Faudziah; Alfred, Rayner

    2016-08-01

    Shape is the main information for leaf feature that most of the current literatures in leaf identification utilize the whole leaf for feature extraction and to be used in the leaf identification process. In this paper, study of half-leaf features extraction for leaf identification is carried out and the results are compared with the results obtained from the leaf identification based on a full-leaf features extraction. Identification and classification is based on shape features that are represented as cosines and sinus angles. Six single classifiers obtained from WEKA and seven ensemble methods are used to compare their performance accuracies over this data. The classifiers were trained using 65 leaves in order to classify 5 different species of preliminary collection of Malaysian medicinal plants. The result shows that half-leaf features extraction can be used for leaf identification without decreasing the predictive accuracy.

  11. Penetration of sunlight into a canopy - Explicit models based on vertical and horizontal leaf projections

    NASA Technical Reports Server (NTRS)

    Otterman, J.; Brakke, T.

    1986-01-01

    The projections of leaf areas onto a horizontal plane and onto a vertical plane are examined for their utility in characterizing canopies for sunlight penetration (direct beam only) models. These projections exactly specify the penetration if the projections on the principal plane of the normals to the top surfaces of the leaves are in the same quadrant as the sun. Inferring the total leaf area from these projections (and therefore the penetration as a function of the total leaf area) is possible only with a large uncertainty (up to + or - 32 percent) because the projections are a specific measure of the total leaf area only if the leaf angle distribution is known. It is expected that this uncertainty could be reduced to more acceptable levels by making an approximate assessment of whether the zenith angle distribution is that of an extremophile canopy.

  12. Leaf Associated Microbial Activities in a Stream Affected by Acid Mine Drainage

    NASA Astrophysics Data System (ADS)

    Schlief, Jeanette

    2004-11-01

    Microbial activity was assessed on birch leaves and plastic strips during 140 days of exposure at three sites in an acidic stream of the Lusatian post-mining landscape, Germany. The sites differed in their degrees of ochre deposition and acidification. The aim of the study was (1) to follow the microbial activities during leaf colonization, (2) to compare the effect of different environmental conditions on leaf associated microbial activities, and (3) to test the microbial availability of leaf litter in acidic mining waters. The activity peaked after 49 days and subsequently decreased gradually at all sites. A formation of iron plaques on leaf surfaces influenced associated microbial activity. It seemed that these plaques inhibit the microbial availability of leaf litter and serve as a microbial habitat by itself. (

  13. Leaf cuticular wax amount and crystal morphology regulate post-harvest water loss in mulberry (Morus species).

    PubMed

    Mamrutha, H M; Mogili, T; Jhansi Lakshmi, K; Rama, N; Kosma, Dylan; Udaya Kumar, M; Jenks, Matthew A; Nataraja, Karaba N

    2010-08-01

    Mulberry leaves are the sole source of food for silkworms (Bombyx mori), and moisture content of the detached leaves fed to silkworms determines silkworm growth and cocoon yield. Since leaf dehydration in commercial sericulture is a serious problem, development of new methods that minimize post-harvest water loss are greatly needed. In the present study, variability in moisture retention capacity (MRC, measured as leaf relative water content after one to 5 h of air-drying) was examined by screening 290 diverse mulberry accessions and the relationship between MRC and leaf surface (cuticular) wax amount was determined. Leaf MRC varied significantly among accessions, and was found to correlate strongly with leaf wax amount. Scanning electron microscopic analysis indicated that leaves having crystalline surface waxes of increased facet size and density were associated with high MRC accessions. Leaf MRC at 5 h after harvest was not related to other parameters such as specific leaf weight, and stomatal frequency and index. This study suggests that mulberry accessions having elevated leaf surface wax amount and crystal size and density exhibit reduced leaf post-harvest water loss, and could provide the foundation for selective breeding of improved cultivars. PMID:20580887

  14. 7 CFR 29.3648 - Thin Leaf (C Group).

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... specifications, and tolerances C1L Choice Quality Light-brown Thin Leaf. Ripe, thin, open leaf structure, smooth... injury tolerance. C2L Fine Quality Light-brown Thin Leaf. Ripe, thin, open leaf structure, smooth, oily... tolerance. C4L Fair Quality Light-brown Thin Leaf. Mature, thin, close leaf structure, rough, lean in...

  15. 7 CFR 29.3648 - Thin Leaf (C Group).

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... specifications, and tolerances C1L Choice Quality Light-brown Thin Leaf. Ripe, thin, open leaf structure, smooth... injury tolerance. C2L Fine Quality Light-brown Thin Leaf. Ripe, thin, open leaf structure, smooth, oily... tolerance. C4L Fair Quality Light-brown Thin Leaf. Mature, thin, close leaf structure, rough, lean in...

  16. 7 CFR 29.3648 - Thin Leaf (C Group).

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... specifications, and tolerances C1L Choice Quality Light-brown Thin Leaf. Ripe, thin, open leaf structure, smooth... injury tolerance. C2L Fine Quality Light-brown Thin Leaf. Ripe, thin, open leaf structure, smooth, oily... tolerance. C4L Fair Quality Light-brown Thin Leaf. Mature, thin, close leaf structure, rough, lean in...

  17. 7 CFR 29.3648 - Thin Leaf (C Group).

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... specifications, and tolerances C1L Choice Quality Light-brown Thin Leaf. Ripe, thin, open leaf structure, smooth... injury tolerance. C2L Fine Quality Light-brown Thin Leaf. Ripe, thin, open leaf structure, smooth, oily... tolerance. C4L Fair Quality Light-brown Thin Leaf. Mature, thin, close leaf structure, rough, lean in...

  18. 7 CFR 29.3648 - Thin Leaf (C Group).

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... tolerance. C4L Fair Quality Light-brown Thin Leaf. Mature, thin, close leaf structure, rough, lean in oil... tolerance. C5L Low Quality Light-brown Thin Leaf Underripe, thin, close leaf structure, rough, lean in oil... tolerance. C4F Fair Quality Medium-brown Thin Leaf. Mature, thin, close leaf structure, rough, lean in...

  19. 7 CFR 29.1162 - Leaf (B Group).

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... Specifications, and Tolerances B1L—Choice Quality Lemon Leaf Ripe, firm leaf structure, medium body, rich in oil... percent. B2L—Fine Quality Lemon Leaf Ripe, firm leaf structure, medium body, rich in oil, deep color.... B3L—Good Quality Lemon Leaf Ripe, firm leaf structure, medium body, oily, strong color...

  20. 7 CFR 29.1162 - Leaf (B Group).

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... Specifications, and Tolerances B1L—Choice Quality Lemon Leaf Ripe, firm leaf structure, medium body, rich in oil... percent. B2L—Fine Quality Lemon Leaf Ripe, firm leaf structure, medium body, rich in oil, deep color.... B3L—Good Quality Lemon Leaf Ripe, firm leaf structure, medium body, oily, strong color...

  1. 7 CFR 29.1162 - Leaf (B Group).

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... Specifications, and Tolerances B1L—Choice Quality Lemon Leaf Ripe, firm leaf structure, medium body, rich in oil... percent. B2L—Fine Quality Lemon Leaf Ripe, firm leaf structure, medium body, rich in oil, deep color.... B3L—Good Quality Lemon Leaf Ripe, firm leaf structure, medium body, oily, strong color...

  2. 7 CFR 29.1162 - Leaf (B Group).

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... Specifications, and Tolerances B1L—Choice Quality Lemon Leaf Ripe, firm leaf structure, medium body, rich in oil... percent. B2L—Fine Quality Lemon Leaf Ripe, firm leaf structure, medium body, rich in oil, deep color.... B3L—Good Quality Lemon Leaf Ripe, firm leaf structure, medium body, oily, strong color...

  3. 7 CFR 29.1162 - Leaf (B Group).

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... Specifications, and Tolerances B1L—Choice Quality Lemon Leaf Ripe, firm leaf structure, medium body, rich in oil... percent. B2L—Fine Quality Lemon Leaf Ripe, firm leaf structure, medium body, rich in oil, deep color.... B3L—Good Quality Lemon Leaf Ripe, firm leaf structure, medium body, oily, strong color...

  4. Weak leaf photosynthesis and nutrient content relationships from tropical vegetation

    NASA Astrophysics Data System (ADS)

    Domingues, T. F.; Ishida, F. Y.; Feldpaush, T.; Saiz, G.; Grace, J.; Meir, P.; Lloyd, J.

    2015-12-01

    Evergreen rain forests and savannas are the two major vegetations of tropical land ecosystems, in terms of land area, biomass, biodiversity, biogeochemical cycles and rates of land use change. Mechanistically understanding ecosystem functioning on such ecosystems is still far from complete, but important for generation of future vegetation scenarios in response to global changes. Leaf photosynthetic rates is a key processes usually represented on land surface-atmosphere models, although data from tropical ecosystems is scarce, considering the high biodiversity they contain. As a shortcut, models usually recur to relationships between leaf nutrient concentration and photosynthetic rates. Such strategy is convenient, given the possibility of global datasets on leave nutrients derived from hyperspectral remote sensing data. Given the importance of Nitrogen on enzyme composition, this nutrient is usually used to infer photosynthetic capacity of leaves. Our experience, based on individual measurements on 1809 individual leaves from 428 species of trees and shrubs naturally occurring on tropical forests and savannas from South America, Africa and Australia, indicates that the relationship between leaf nitrogen and its assimilation capacity is weak. Therefore, leaf Nitrogen alone is a poor predictor of photosynthetic rates of tropical vegetation. Phosphorus concentrations from tropical soils are usually low and is often implied that this nutrient limits primary productivity of tropical vegetation. Still, phosphorus (or other nutrients) did not exerted large influence over photosynthetic capacity, although potassium influenced vegetation structure and function. Such results draw attention to the risks of applying universal nitrogen-photosynthesis relationships on biogeochemical models. Moreover, our data suggests that affiliation of plant species within phylogenetic hierarchy is an important aspect in understanding leaf trait variation. The lack of a strong single

  5. SPAD-based leaf nitrogen estimation is impacted by environmental factors and crop leaf characteristics

    PubMed Central

    Xiong, Dongliang; Chen, Jia; Yu, Tingting; Gao, Wanlin; Ling, Xiaoxia; Li, Yong; Peng, Shaobing; Huang, Jianliang

    2015-01-01

    Chlorophyll meters are widely used to guide nitrogen (N) management by monitoring leaf N status in agricultural systems, but the effects of environmental factors and leaf characteristics on leaf N estimations are still unclear. In the present study, we estimated the relationships among SPAD readings, chlorophyll content and leaf N content per leaf area for seven species grown in multiple environments. There were similar relationships between SPAD readings and chlorophyll content per leaf area for the species groups, but the relationship between chlorophyll content and leaf N content per leaf area, and the relationship between SPAD readings and leaf N content per leaf area varied widely among the species groups. A significant impact of light-dependent chloroplast movement on SPAD readings was observed under low leaf N supplementation in both rice and soybean but not under high N supplementation. Furthermore, the allocation of leaf N to chlorophyll was strongly influenced by short-term changes in growth light. We demonstrate that the relationship between SPAD readings and leaf N content per leaf area is profoundly affected by environmental factors and leaf features of crop species, which should be accounted for when using a chlorophyll meter to guide N management in agricultural systems. PMID:26303807

  6. Leaf physiognomy and climate: A multivariate analysis

    NASA Astrophysics Data System (ADS)

    Davis, J. M.; Taylor, S. E.

    1980-11-01

    Research has demonstrated that leaf physiognomy is representative of the local or microclimate conditions under which plants grow. The physiognomy of leaf samples from Oregon, Michigan, Missouri, Tennessee, and the Panama Canal Zone has been related to the microclimate using Walter diagrams and Thornthwaite water-budget data. A technique to aid paleoclimatologists in identifying the nature of the microclimate from leaf physiognomy utilizes statistical procedures to classify leaf samples into one of six microclimate regimes based on leaf physiognomy information available from fossilized samples.

  7. Hormonal regulation of leaf senescence in Lilium.

    PubMed

    Arrom, Laia; Munné-Bosch, Sergi

    2012-10-15

    In addition to floral senescence and longevity, the control of leaf senescence is a major factor determining the quality of several cut flowers, including Lilium, in the commercial market. To better understand the physiological process underlying leaf senescence in this species, we evaluated: (i) endogenous variation in the levels of phytohormones during leaf senescence, (ii) the effects of leaf darkening in senescence and associated changes in phytohormones, and (iii) the effects of spray applications of abscisic acid (ABA) and pyrabactin on leaf senescence. Results showed that while gibberellin 4 (GA(4)) and salicylic acid (SA) contents decreased, that of ABA increased during the progression of leaf senescence. However, dark-induced senescence increased ABA levels, but did not affect GA(4) and SA levels, which appeared to correlate more with changes in air temperature and/or photoperiod than with the induction of leaf senescence. Furthermore, spray applications of pyrabactin delayed the progression of leaf senescence in cut flowers. Thus, we conclude that (i) ABA plays a major role in the regulation of leaf senescence in Lilium, (ii) darkness promotes leaf senescence and increases ABA levels, and (iii) exogenous applications of pyrabactin inhibit leaf senescence in Lilium, therefore suggesting that it acts as an antagonist of ABA in senescing leaves of cut lily flowers. PMID:22854182

  8. Leaf herbivory and nutrients increase nectar alkaloids.

    PubMed

    Adler, Lynn S; Wink, Michael; Distl, Melanie; Lentz, Amanda J

    2006-08-01

    Correlations between traits may constrain ecological and evolutionary responses to multispecies interactions. Many plants produce defensive compounds in nectar and leaves that could influence interactions with pollinators and herbivores, but the relationship between nectar and leaf defences is entirely unexplored. Correlations between leaf and nectar traits may be mediated by resources and prior damage. We determined the effect of nutrients and leaf herbivory by Manduca sexta on Nicotiana tabacum nectar and leaf alkaloids, floral traits and moth oviposition. We found a positive phenotypic correlation between nectar and leaf alkaloids. Herbivory induced alkaloids in nectar but not in leaves, while nutrients increased alkaloids in both tissues. Moths laid the most eggs on damaged, fertilized plants, suggesting a preference for high alkaloids. Induced nectar alkaloids via leaf herbivory indicate that species interactions involving leaf and floral tissues are linked and should not be treated as independent phenomena in plant ecology or evolution. PMID:16913940

  9. Delivering high-resolution landmarks using inkjet micropatterning for spatial monitoring of leaf expansion

    PubMed Central

    2011-01-01

    Background Inkjet micropatterning is a versatile deposition technique with broad applications in numerous fields. However, its application in plant science is largely unexplored. Leaf expansion is one of the most important parameters in the field of plant science and many methods have been developed to examine differential expansion rates of different parts of the leaf lamina. Among them, methods based on the tracking of natural landmarks through digital imaging require a complicated setup in which the leaf must remain fixed and under tension. Furthermore, the resolution is limited to that of the natural landmarks, which are often difficult to find, particularly in young leaves. To study the fine scale expansion dynamics of the leaf lamina using artificial landmarks it is necessary to place small, noninvasive marks on a leaf surface and then recover the location of those marks after a period of time. Results To monitor leaf expansion in two dimensions, at very fine scales, we used a custom designed inkjet micropatterning system to print a grid composed of c. 0.19 mm2 cells on small developing leaves of ivy (Hedera helix) using 40 μm dots at a spacing of c. 91 μm. The leaves in different growing stages were imaged under magnification to extract the coordinates of the marks which were then used in subsequent computer-assisted leaf expansion analyses. As an example we obtained quantified global and local expansion information and created expansion maps over the entire leaf surface. The results reveal a striking pattern of fine-scale expansion differences over short periods of time. In these experiments, the base of the leaf is a "cold spot" for expansion, while the leaf sinuses are "hot spots" for expansion. We have also measured a strong shading effect on leaf expansion. We discuss the features required to build an inkjet printing apparatus optimized for use in plant science, which will further maximize the range of tissues that can be printed at these scales

  10. The relationship of leaf photosynthetic traits - V cmax and J max - to leaf nitrogen, leaf phosphorus, and specific leaf area: a meta-analysis and modeling study.

    PubMed

    Walker, Anthony P; Beckerman, Andrew P; Gu, Lianhong; Kattge, Jens; Cernusak, Lucas A; Domingues, Tomas F; Scales, Joanna C; Wohlfahrt, Georg; Wullschleger, Stan D; Woodward, F Ian

    2014-08-01

    Great uncertainty exists in the global exchange of carbon between the atmosphere and the terrestrial biosphere. An important source of this uncertainty lies in the dependency of photosynthesis on the maximum rate of carboxylation (V cmax) and the maximum rate of electron transport (J max). Understanding and making accurate prediction of C fluxes thus requires accurate characterization of these rates and their relationship with plant nutrient status over large geographic scales. Plant nutrient status is indicated by the traits: leaf nitrogen (N), leaf phosphorus (P), and specific leaf area (SLA). Correlations between V cmax and J max and leaf nitrogen (N) are typically derived from local to global scales, while correlations with leaf phosphorus (P) and specific leaf area (SLA) have typically been derived at a local scale. Thus, there is no global-scale relationship between V cmax and J max and P or SLA limiting the ability of global-scale carbon flux models do not account for P or SLA. We gathered published data from 24 studies to reveal global relationships of V cmax and J max with leaf N, P, and SLA. V cmax was strongly related to leaf N, and increasing leaf P substantially increased the sensitivity of V cmax to leaf N. J max was strongly related to V cmax, and neither leaf N, P, or SLA had a substantial impact on the relationship. Although more data are needed to expand the applicability of the relationship, we show leaf P is a globally important determinant of photosynthetic rates. In a model of photosynthesis, we showed that at high leaf N (3 gm(-2)), increasing leaf P from 0.05 to 0.22 gm(-2) nearly doubled assimilation rates. Finally, we show that plants may employ a conservative strategy of J max to V cmax coordination that restricts photoinhibition when carboxylation is limiting at the expense of maximizing photosynthetic rates when light is limiting. PMID:25473475

  11. The relationship of leaf photosynthetic traits – Vcmax and Jmax – to leaf nitrogen, leaf phosphorus, and specific leaf area: a meta-analysis and modeling study

    PubMed Central

    Walker, Anthony P; Beckerman, Andrew P; Gu, Lianhong; Kattge, Jens; Cernusak, Lucas A; Domingues, Tomas F; Scales, Joanna C; Wohlfahrt, Georg; Wullschleger, Stan D; Woodward, F Ian

    2014-01-01

    Great uncertainty exists in the global exchange of carbon between the atmosphere and the terrestrial biosphere. An important source of this uncertainty lies in the dependency of photosynthesis on the maximum rate of carboxylation (Vcmax) and the maximum rate of electron transport (Jmax). Understanding and making accurate prediction of C fluxes thus requires accurate characterization of these rates and their relationship with plant nutrient status over large geographic scales. Plant nutrient status is indicated by the traits: leaf nitrogen (N), leaf phosphorus (P), and specific leaf area (SLA). Correlations between Vcmax and Jmax and leaf nitrogen (N) are typically derived from local to global scales, while correlations with leaf phosphorus (P) and specific leaf area (SLA) have typically been derived at a local scale. Thus, there is no global-scale relationship between Vcmax and Jmax and P or SLA limiting the ability of global-scale carbon flux models do not account for P or SLA. We gathered published data from 24 studies to reveal global relationships of Vcmax and Jmax with leaf N, P, and SLA. Vcmax was strongly related to leaf N, and increasing leaf P substantially increased the sensitivity of Vcmax to leaf N. Jmax was strongly related to Vcmax, and neither leaf N, P, or SLA had a substantial impact on the relationship. Although more data are needed to expand the applicability of the relationship, we show leaf P is a globally important determinant of photosynthetic rates. In a model of photosynthesis, we showed that at high leaf N (3 gm−2), increasing leaf P from 0.05 to 0.22 gm−2 nearly doubled assimilation rates. Finally, we show that plants may employ a conservative strategy of Jmax to Vcmax coordination that restricts photoinhibition when carboxylation is limiting at the expense of maximizing photosynthetic rates when light is limiting. PMID:25473475

  12. Intra- and inter-community variation in leaf water repellency along a 4000 m elevation transect in the Peruvian Andes

    NASA Astrophysics Data System (ADS)

    Goldsmith, G. R.; Doughty, C.; Bentley, L. P.; Shenkin, A.; Castro-Ccoscco, R. M.; Salinas, N.; Malhi, Y.

    2014-12-01

    Leaf water repellency is a measure of the hydrophobicity, or wettability, of leaf surfaces. At the scale of the plant, leaf water repellency can affect gas exchange, nutrient exchange, and pathogen growth. At the scale of the ecosystem, it can affect canopy water storage, throughfall, and evaporation. To date, very few studies have measured intra- and inter- community variation in leaf water repellency of tropical forest ecosystems. In the context of a broad survey of plant functional traits, we measured leaf water repellency in nine forest plots occurring across a 4000 m elevation gradient in the eastern Andes of Peru. Observed angles of incidence (63 ± 13°) indicate high leaf wettability, with no significant difference between sun and shade leaves. In contrast with previous research along elevation gradients, we find no strong evidence for variation across sites, but rather find high variation within a given site. Finally, we find that leaf water repellency may be predicted using sunlit leaf spectra with a low RMSE (<25% of the mean), indicating that future research on leaf water repellency could be carried out using high resolution hyperspectral remote sensing. As the climate of tropical ecosystems changes, the resultant changes in leaf water repellency will impact plants, communities and ecosystems. Our results inform our understanding of where and to what extent these impacts are most likely to occur.

  13. From buds to litter: seasonal changes in leaf wax concentrations and carbon isotopes and implications for the geologic past

    NASA Astrophysics Data System (ADS)

    Suh, Y. J.; Diefendorf, A. F.

    2014-12-01

    The carbon isotope composition (δ13C) of leaf waxes, such as n-alkanes, have extensively been used in paleoenvironmental studies for reconstruction of the past vegetation, climate and carbon cycling. There is however little information available on the seasonal variation of leaf wax concentration and δ13C in modern plants and when the δ13C signal is set. This lack of information confounds interpretations of leaf wax δ13C in sedimentary archives. To address this gap, this study investigates temporal changes in n-alkane and n-alkanoic acid δ13C values in several species (Acer rubrum, Acer saccharum, Ulmus Americana, Sassafras albidum, and Juniperus virginiana) within a single temperate deciduous forest stand in southern Ohio. We sampled atmospheric air, buds, leaves, leaf litter, and surface soil weekly during leaf flush and biweekly thereafter. In A. rubrum, A. saccharum, and U. Americana, buds had one or two dominant n-alkanes, such as C29 and C31. After leaf flush, the concentrations of shorter n-alkanes (C23~C27) significantly increased relative to the longer chain-lengths. We are currently analyzing remaining samples from the growing season and are analyzing bulk leaf and leaf wax (n-alkanes, n-alkanoic acids) δ13C values. This information will be important for identifying environmental and physiological controls on leaf wax δ13C and will improve interpretations of leaf wax δ13C preserved in the geologic record.

  14. Kaolin-based foliar reflectant and water deficit influence Malbec leaf and berry temperature, pigments, and photosynthesis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The effects of a kaolin-based foliar reflectant on traits of commercial interest in the red-skinned wine grape cultivar Malbec (Vitis vinifera L.) were evaluated over three growing seasons by measuring the surface temperatures of leaves and clusters, leaf-level assimilation, leaf and berry pigment c...

  15. Leaf Senescence by Magnesium Deficiency

    PubMed Central

    Tanoi, Keitaro; Kobayashi, Natsuko I.

    2015-01-01

    Magnesium ions (Mg2+) are the second most abundant cations in living plant cells, and they are involved in various functions, including photosynthesis, enzyme catalysis, and nucleic acid synthesis. Low availability of Mg2+ in an agricultural field leads to a decrease in yield, which follows the appearance of Mg-deficient symptoms such as chlorosis, necrotic spots on the leaves, and droop. During the last decade, a variety of physiological and molecular responses to Mg2+ deficiency that potentially link to leaf senescence have been recognized, allowing us to reconsider the mechanisms of Mg2+ deficiency. This review focuses on the current knowledge about the physiological responses to Mg2+ deficiency including a decline in transpiration, accumulation of sugars and starch in source leaves, change in redox states, increased oxidative stress, metabolite alterations, and a decline in photosynthetic activity. In addition, we refer to the molecular responses that are thought to be related to leaf senescence. With these current data, we give an overview of leaf senescence induced by Mg deficiency. PMID:27135350

  16. LeafJ: an ImageJ plugin for semi-automated leaf shape measurement.

    PubMed

    Maloof, Julin N; Nozue, Kazunari; Mumbach, Maxwell R; Palmer, Christine M

    2013-01-01

    High throughput phenotyping (phenomics) is a powerful tool for linking genes to their functions (see review and recent examples). Leaves are the primary photosynthetic organ, and their size and shape vary developmentally and environmentally within a plant. For these reasons studies on leaf morphology require measurement of multiple parameters from numerous leaves, which is best done by semi-automated phenomics tools. Canopy shade is an important environmental cue that affects plant architecture and life history; the suite of responses is collectively called the shade avoidance syndrome (SAS). Among SAS responses, shade induced leaf petiole elongation and changes in blade area are particularly useful as indices. To date, leaf shape programs (e.g. SHAPE, LAMINA, LeafAnalyzer, LEAFPROCESSOR) can measure leaf outlines and categorize leaf shapes, but can not output petiole length. Lack of large-scale measurement systems of leaf petioles has inhibited phenomics approaches to SAS research. In this paper, we describe a newly developed ImageJ plugin, called LeafJ, which can rapidly measure petiole length and leaf blade parameters of the model plant Arabidopsis thaliana. For the occasional leaf that required manual correction of the petiole/leaf blade boundary we used a touch-screen tablet. Further, leaf cell shape and leaf cell numbers are important determinants of leaf size. Separate from LeafJ we also present a protocol for using a touch-screen tablet for measuring cell shape, area, and size. Our leaf trait measurement system is not limited to shade-avoidance research and will accelerate leaf phenotyping of many mutants and screening plants by leaf phenotyping. PMID:23380664

  17. Seasonality of litterfall and leaf decomposition in a cerrado site.

    PubMed

    Valenti, M W; Cianciaruso, M V; Batalha, M A

    2008-08-01

    We investigated annual litterfall and leaf decomposition rate in a cerrado site. We collected woody plant litter monthly from April 2001 to March 2002 and from July 2003 to June 2004. We placed systematically 13 litter traps (0.5 x 0.5 m) in a line, 10 m one from the other. We sorted litter into 'leaves', 'stems', 'reproductive structures', and 'miscellanea' fractions, oven-dried them at 80 degrees C until constant mass and weighed the dry material. To assess leaf decomposition rate, we packed leaves recently shed by plants in litter bags. We placed seven sets of nine litter bags in a line, 10 m one from the other, on the soil surface and collected nine bags each time after 1, 2, 3, 4, 6, 9, and 12 months. Total and leaf litter productions showed a seasonal pattern. Leaf litterfall was the phenological attribute that showed the strongest response to seasonality and drought. Decomposition was slower in the cerrado that we studied compared to a more closed cerrado physiognomy, reflecting their structural and environmental differences. Thus, decomposition rates seem to increase from open to closed cerrado physiognomies, probably related to an increase of humidity and nutrients in the soil. PMID:18833466

  18. Bidirectional reflectance, leaf optical and physiological properties of prairie vegetation

    NASA Technical Reports Server (NTRS)

    Walter-Shea, E. A.; Blad, B. L.; Starks, P. J; Hays, C. J.; Mesarch, M. A.; Middleton, E. M.

    1990-01-01

    A modular multiband radiometer is used to measure reflected radiation from the vegetative surface of a prairie. The data are compared to estimates of incoming radiation by measuring the reflection from a molded halon panel, and the bidirectional reflectance factors are measured at seven view-zenith angles and various incidence angles. The canopy-reflectance results are compared to leaf-optical and other vegetative physiological properties, and a direct relationship is reported.

  19. Leaf P increase outpaces leaf N in an Inner Mongolia grassland over 27 years.

    PubMed

    Mi, Zhaorong; Huang, Yuanyuan; Gan, Huijie; Zhou, Wenjia; Flynn, Dan F B; He, Jin-Sheng

    2015-01-01

    The dynamics of leaf nitrogen (N) and phosphorus (P) have been intensively explored in short-term experiments, but rarely at longer timescales. Here, we investigated leaf N : P stoichiometry over a 27-year interval in an Inner Mongolia grassland by comparing leaf N : P concentration of 2006 with that of 1979. Across 80 species, both leaf N and P increased, but the increase in leaf N lagged behind that of leaf P, leading to a significant decrease in the N : P ratio. These changes in leaf N : P stoichiometry varied among functional groups. For leaf N, grasses increased, woody species tended to increase, whereas forbs showed no change. Unlike leaf N, leaf P of grasses and forbs increased, whereas woody species showed no change. Such changes may reflect N deposition and P release induced by soil acidification over the past decades. The interannual effect of precipitation may somewhat have reduced the soil available N, leading to the more modest increase of leaf N than of leaf P. Thus, leaf N : P stoichiometry significantly responded to long-term environmental changes in this temperate steppe, but different functional groups responded differently. Our results indicate that conclusions of plant stoichiometry under short-term N fertilization should be treated with caution when extrapolating to longer timescales. PMID:25589490

  20. Simulating Springtime Temperature Patterns in the Community Atmosphere Model Coupled to the Community Land Model Using Prognostic Leaf Area.

    NASA Astrophysics Data System (ADS)

    Levis, Samuel; Bonan, Gordon B.

    2004-12-01

    Observations show that emergence of foliage in springtime slows surface air temperature warming as a result of greater transpiration. Model simulations with the Community Atmosphere Model coupled to the Community Land Model confirm that evapotranspiration contributes to this pattern and that this pattern occurs more reliably with prognostic leaf area as opposed to prescribed leaf area. With prescribed leaf area, leaves emerge independent of prevailing environmental conditions, which may preclude photosynthesis from occurring. In contrast, prognostic leaf area ensures that leaves emerge when conditions are favorable for photosynthesis, and thus transpiration. These results reveal a dynamic coupling between the atmosphere and vegetation in which the observed reduction in the springtime warming trend only occurs when photosynthesis, stomatal conductance, and leaf emergence are synchronized with the surface climate.


  1. Reversible superhydrophilicity and superhydrophobicity on a lotus-leaf pattern.

    PubMed

    de Leon, Al; Advincula, Rigoberto C

    2014-12-24

    A facile approach of fabricating a temperature-responsive coating capable of switching reversibly from being superhydrophobic to superhydrophilic is presented. The approach combines micromolding, layer-by-layer assembly of the polymer macroinitiators, and surface-initiated polymerization. Changing between superhydrophobicity and superhydrophilicity depends heavily on the surface roughness and the switching of the surface energy levels. In this study, surface roughness was introduced by replicating the surface morphology of a lotus leaf. The switching of surface energy levels was made possible by grafting a temperature-responsive polymer brush. Wetting studies reveal that the reported approach not only replicates nature but also improves its property by making it responsive to stimulus. PMID:25412015

  2. Leaf breakdown in streams differing in catchment land use

    USGS Publications Warehouse

    Paul, M.J.; Meyer, J.L.; Couch, C.A.

    2006-01-01

    1. The impact of changes in land use on stream ecosystem function is poorly understood. We studied leaf breakdown, a fundamental process of stream ecosystems, in streams that represent a range of catchment land use in the Piedmont physiographic province of the south-eastern United States. 2. We placed bags of chalk maple (Acer barbatum) leaves in similar-sized streams in 12 catchments of differing dominant land use: four forested, three agricultural, two suburban and three urban catchments. We measured leaf mass, invertebrate abundance and fungal biomass in leaf bags over time. 3. Leaves decayed significantly faster in agricultural (0.0465 day-1) and urban (0.0474 day-1) streams than in suburban (0.0173 day-1) and forested (0.0100 day-1) streams. Additionally, breakdown rates in the agricultural and urban streams were among the fastest reported for deciduous leaves in any stream. Nutrient concentrations in agricultural streams were significantly higher than in any other land-use type. Fungal biomass associated with leaves was significantly lower in urban streams; while shredder abundance in leaf bags was significantly higher in forested and agricultural streams than in suburban and urban streams. Storm runoff was significantly higher in urban and suburban catchments that had higher impervious surface cover than forested or agricultural catchments. 4. We propose that processes accelerating leaf breakdown in agricultural and urban streams were not the same: faster breakdown in agricultural streams was due to increased biological activity as a result of nutrient enrichment, whereas faster breakdown in urban streams was a result of physical fragmentation resulting from higher storm runoff. ?? 2006 The Authors.

  3. Classification and quantification of leaf curvature

    PubMed Central

    Liu, Zhongyuan; Jia, Liguo; Mao, Yanfei; He, Yuke

    2010-01-01

    Various mutants of Arabidopsis thaliana deficient in polarity, cell division, and auxin response are characterized by certain types of leaf curvature. However, comparison of curvature for clarification of gene function can be difficult without a quantitative measurement of curvature. Here, a novel method for classification and quantification of leaf curvature is reported. Twenty-two mutant alleles from Arabidopsis mutants and transgenic lines deficient in leaf flatness were selected. The mutants were classified according to the direction, axis, position, and extent of leaf curvature. Based on a global measure of whole leaves and a local measure of four regions in the leaves, the curvature index (CI) was proposed to quantify the leaf curvature. The CI values accounted for the direction, axis, position, and extent of leaf curvature in all of the Arabidopsis mutants grown in growth chambers. Comparison of CI values between mutants reveals the spatial and temporal variations of leaf curvature, indicating the strength of the mutant alleles and the activities of the corresponding genes. Using the curvature indices, the extent of curvature in a complicated genetic background becomes quantitative and comparable, thus providing a useful tool for defining the genetic components of leaf development and to breed new varieties with leaf curvature desirable for the efficient capture of sunlight for photosynthesis and high yields. PMID:20400533

  4. Leaf Shape Recognition using Centroid Contour Distance

    NASA Astrophysics Data System (ADS)

    Hasim, Abdurrasyid; Herdiyeni, Yeni; Douady, Stephane

    2016-01-01

    This research recognizes the leaf shape using Centroid Contour Distance (CCD) as shape descriptor. CCD is an algorithm of shape representation contour-based approach which only exploits boundary information. CCD calculates the distance between the midpoint and the points on the edge corresponding to interval angle. Leaf shapes that included in this study are ellips, cordate, ovate, and lanceolate. We analyzed 200 leaf images of tropical plant. Each class consists of 50 images. The best accuracy is obtained by 96.67%. We used Probabilistic Neural Network to classify the leaf shape. Experimental results demonstrated the effectiveness of the proposed approach for shape recognition with high accuracy.

  5. 7 CFR 30.2 - Leaf tobacco.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... stemming, sweating or fermenting, and conditioning are not regarded as manufacturing processes. Leaf tobacco does not include any manufactured or semimanufactured tobacco, stems which have been removed...

  6. 7 CFR 30.2 - Leaf tobacco.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... stemming, sweating or fermenting, and conditioning are not regarded as manufacturing processes. Leaf tobacco does not include any manufactured or semimanufactured tobacco, stems which have been removed...

  7. 7 CFR 30.2 - Leaf tobacco.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... stemming, sweating or fermenting, and conditioning are not regarded as manufacturing processes. Leaf tobacco does not include any manufactured or semimanufactured tobacco, stems which have been removed...

  8. 7 CFR 30.2 - Leaf tobacco.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... stemming, sweating or fermenting, and conditioning are not regarded as manufacturing processes. Leaf tobacco does not include any manufactured or semimanufactured tobacco, stems which have been removed...

  9. 7 CFR 30.2 - Leaf tobacco.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... stemming, sweating or fermenting, and conditioning are not regarded as manufacturing processes. Leaf tobacco does not include any manufactured or semimanufactured tobacco, stems which have been removed...

  10. 7 CFR 28.471 - Below Leaf Grade Cotton.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Below Leaf Grade Cotton. 28.471 Section 28.471... REGULATIONS COTTON CLASSING, TESTING, AND STANDARDS Standards Below Leaf Grade Cotton § 28.471 Below Leaf Grade Cotton. Below leaf grade cotton is American Upland cotton which is lower in leaf grade than...

  11. 7 CFR 28.471 - Below Leaf Grade Cotton.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 2 2011-01-01 2011-01-01 false Below Leaf Grade Cotton. 28.471 Section 28.471... REGULATIONS COTTON CLASSING, TESTING, AND STANDARDS Standards Below Leaf Grade Cotton § 28.471 Below Leaf Grade Cotton. Below leaf grade cotton is American Upland cotton which is lower in leaf grade than...

  12. 7 CFR 28.471 - Below Leaf Grade Cotton.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 2 2012-01-01 2012-01-01 false Below Leaf Grade Cotton. 28.471 Section 28.471... REGULATIONS COTTON CLASSING, TESTING, AND STANDARDS Standards Below Leaf Grade Cotton § 28.471 Below Leaf Grade Cotton. Below leaf grade cotton is American Upland cotton which is lower in leaf grade than...

  13. 7 CFR 28.471 - Below Leaf Grade Cotton.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 2 2014-01-01 2014-01-01 false Below Leaf Grade Cotton. 28.471 Section 28.471... REGULATIONS COTTON CLASSING, TESTING, AND STANDARDS Standards Below Leaf Grade Cotton § 28.471 Below Leaf Grade Cotton. Below leaf grade cotton is American Upland cotton which is lower in leaf grade than...

  14. 7 CFR 28.471 - Below Leaf Grade Cotton.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 2 2013-01-01 2013-01-01 false Below Leaf Grade Cotton. 28.471 Section 28.471... REGULATIONS COTTON CLASSING, TESTING, AND STANDARDS Standards Below Leaf Grade Cotton § 28.471 Below Leaf Grade Cotton. Below leaf grade cotton is American Upland cotton which is lower in leaf grade than...

  15. 7 CFR 28.466 - Leaf Grade 6.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf Grade 6. 28.466 Section 28.466 Agriculture..., TESTING, AND STANDARDS Standards Official Cotton Standards of the United States for the Leaf Grade of American Upland Cotton § 28.466 Leaf Grade 6. Leaf Grade 6 is leaf which is within the range represented...

  16. 7 CFR 28.464 - Leaf Grade 4.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf Grade 4. 28.464 Section 28.464 Agriculture..., TESTING, AND STANDARDS Standards Official Cotton Standards of the United States for the Leaf Grade of American Upland Cotton § 28.464 Leaf Grade 4. Leaf Grade 4 is leaf which is within the range represented...

  17. 7 CFR 28.465 - Leaf Grade 5.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf Grade 5. 28.465 Section 28.465 Agriculture..., TESTING, AND STANDARDS Standards Official Cotton Standards of the United States for the Leaf Grade of American Upland Cotton § 28.465 Leaf Grade 5. Leaf Grade 5 is leaf which is within the range represented...

  18. 7 CFR 28.462 - Leaf Grade 2.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf Grade 2. 28.462 Section 28.462 Agriculture..., TESTING, AND STANDARDS Standards Official Cotton Standards of the United States for the Leaf Grade of American Upland Cotton § 28.462 Leaf Grade 2. Leaf Grade 2 is leaf which is within the range represented...

  19. 7 CFR 28.463 - Leaf Grade 3.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf Grade 3. 28.463 Section 28.463 Agriculture..., TESTING, AND STANDARDS Standards Official Cotton Standards of the United States for the Leaf Grade of American Upland Cotton § 28.463 Leaf Grade 3. Leaf Grade 3 is leaf which is within the range represented...

  20. 7 CFR 28.467 - Leaf Grade 7.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf Grade 7. 28.467 Section 28.467 Agriculture..., TESTING, AND STANDARDS Standards Official Cotton Standards of the United States for the Leaf Grade of American Upland Cotton § 28.467 Leaf Grade 7. Leaf Grade 7 is leaf which is within the range represented...

  1. 7 CFR 28.461 - Leaf Grade 1.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf Grade 1. 28.461 Section 28.461 Agriculture..., TESTING, AND STANDARDS Standards Official Cotton Standards of the United States for the Leaf Grade of American Upland Cotton § 28.461 Leaf Grade 1. Leaf Grade 1 is leaf which is within the range represented...

  2. Sclerophylly and leaf anatomical traits of five field-grown olive cultivars growing under drought conditions.

    PubMed

    Bacelar, Eunice A; Correia, Carlos M; Moutinho-Pereira, José M; Gonçalves, Berta C; Lopes, João I; Torres-Pereira, José M G

    2004-02-01

    Leaf-level morphological and structural adaptations to reduce water loss were examined in five olive (Olea europaea L.) tree cultivars (Arbequina, Blanqueta, Cobrançosa, Manzanilla and Negrinha) growing under field conditions with low water availability. Leaf measurements included leaf tissue thickness, stomatal density, leaf area, leaf mass per unit area, density of leaf tissue, relative water content, succulence, water saturation deficit, water content at saturation and cuticular transpiration rate. We found considerable genotypic differences among the cultivars. Negrinha, Manzanilla and Cobrançosa had more morphological and structural leaf adaptations to protect against water loss than the other cultivars. Manzanilla and Negrinha enhanced their sclerophylly by building parenchyma tissues and increasing protective structures like the upper cuticle and both the upper and lower epidermis. Cobrançosa exhibited good protection against water loss through high density of foliar tissue and by thick cuticle and trichome layers. Compared with the Negrinha, Manzanilla and Cobrançosa cultivars, Arbequina leaves had a thinner trichome layer, implying that the leaves were less protected against water loss; however, the development of smaller leaves may reduce water loss at the whole-plant level. Among cultivars, Blanqueta had the largest leaves and some anatomical traits that may lead to high water loss, especially from the adaxial surface. The mechanisms employed by the cultivars to cope with summer stress are discussed at the morpho-structural level. PMID:14676039

  3. Leaf ontogeny and demography explain photosynthetic seasonality in Amazon evergreen forests

    NASA Astrophysics Data System (ADS)

    Wu, J.; Albert, L.; Lopes, A. P.; Restrepo-Coupe, N.; Hayek, M.; Wiedemann, K. T.; Guan, K.; Stark, S. C.; Prohaska, N.; Tavares, J. V.; Marostica, S. F.; Kobayashi, H.; Ferreira, M. L.; Campos, K.; Silva, R. D.; Brando, P. M.; Dye, D. G.; Huxman, T. E.; Huete, A. R.; Nelson, B. W.; Saleska, S. R.

    2015-12-01

    Photosynthetic seasonality couples the evolutionary ecology of plant leaves to large-scale rhythms of carbon and water exchanges that are important feedbacks to climate. However, the extent, magnitude, and controls on photosynthetic seasonality of carbon-rich tropical forests are poorly resolved, controversial in the remote sensing literature, and inadequately represented in most earth system models. Here we show that ecosystem-scale phenology (measured by photosynthetic capacity), rather than environmental seasonality, is the primary driver of photosynthetic seasonality at four Amazon evergreen forests spanning gradients in rainfall seasonality, forest composition, and flux seasonality. We further demonstrate that leaf ontogeny and demography explain most of this ecosystem phenology at two central Amazon evergreen forests, using a simple leaf-cohort canopy model that integrates eddy covariance-derived CO2 fluxes, novel near-surface camera-detected leaf phenology, and ground observations of litterfall and leaf physiology. The coordination of new leaf growth and old leaf divestment (litterfall) during the dry season shifts canopy composition towards younger leaves with higher photosynthetic efficiency, driving large seasonal increases (~27%) in ecosystem photosynthetic capacity. Leaf ontogeny and demography thus reconciles disparate observations of forest seasonality from leaves to eddy flux towers to satellites. Strategic incorporation of such whole-plant coordination processes as phenology and ontogeny will improve ecological, evolutionary and earth system theories describing tropical forests structure and function, allowing more accurate representation of forest dynamics and feedbacks to climate in earth system models.

  4. Theoretical and experimental insights into effects of wind on leaf heat and gas exchange

    NASA Astrophysics Data System (ADS)

    Schymanski, Stanislaus J.; Or, Dani

    2014-05-01

    Transpiration and heat exchange by plant leaves are coupled physiological processes of significant importance for surface-climate interactions and ecohydrology. The common practice of modelling transpiration as an isothermal process (assuming equal leaf and air temperatures) may introduce significant bias into estimates of transpiration rates and water use efficiency (WUE, the amount of carbon gained by photosynthesis per unit of water lost by transpiration). In contrast, explicit consideration of stomatal and leaf boundary layer resistances in series and the leaf energy balance in a physically-based model led to some surprising results, such as suppressed transpiration rates for increasing wind speed at constant stomatal conductance. The model predicts that for high wind velocities, the same leaf conductance (for water vapour and carbon dioxide) can be maintained with less evaporative losses. If this leaf-scale effect is consistent across most leaves, it may have profound implications for canopy-scale water use efficiency under globally decreasing wind speeds. This presentation reports the results of a systematic study of the effect of wind speed on leaf heat and gas exchange rates and introduces a novel experimental design to verify the modelling results using an insulated wind tunnel and artificial leaves with defined pore geometries, allowing to measure leaf-scale latent and sensible heat fluxes independently. First experimental results and new insights will be highlighted.

  5. [Applicability analysis of spatially explicit model of leaf litter in evergreen broad-leaved forests].

    PubMed

    Zhao, Qing-Qing; Liu, He-Ming; Jonard, Mathieu; Wang, Zhang-Hua; Wang, Xi-Hua

    2014-11-01

    The spatially explicit model of leaf litter can help to understand its dispersal process, which is very important to predict the distribution pattern of leaves on the surface of the earth. In this paper, the spatially explicit model of leaf litter was developed for 20 tree species using litter trap data from the mapped forest plot in an evergreen broad-leaved forest in Tiantong, Zhejiang Pro- vince, eastern China. Applicability of the model was analyzed. The model assumed an allometric equation between diameter at breast height (DBH) and leaf litter amount, and the leaf litter declined exponentially with the distance. Model parameters were estimated by the maximum likelihood method. Results showed that the predicted and measured leaf litter amounts were significantly correlated, but the prediction accuracies varied widely for the different tree species, averaging at 49.3% and ranging from 16.0% and 74.0%. Model qualities of tree species significantly correlated with the standard deviations of the leaf litter amount per trap, DBH of the tree species and the average leaf dry mass of tree species. There were several ways to improve the forecast precision of the model, such as installing the litterfall traps according to the distribution of the tree to cover the different classes of the DBH and distance apart from the parent trees, determining the optimal dispersal function of each tree species, and optimizing the existing dispersal function. PMID:25898606

  6. Does citrus leaf miner impair hydraulics and fitness of citrus host plants?

    PubMed

    Raimondo, Fabio; Trifilò, Patrizia; Gullo, Maria A Lo

    2013-12-01

    Gas exchange and hydraulic features were measured in leaves of three different Citrus species (Citrus aurantium L., Citrus limon L., Citrus  ×  paradisii Macfad) infested by Phyllocnistis citrella Staiton, with the aim to quantify the impact of this pest on leaf hydraulics and, ultimately, on plant fitness. Infested leaves were characterized by the presence on the leaf blade of typical snake-shaped mines and, in some cases, of a crumpled leaf blade. Light microscopy showed that leaf crumpling was induced by damage to the cuticular layer. In all three Citrus species examined: (a) the degree of infestation did not exceed 10% of the total surface area of infested plants; (b) control and infested leaves showed similar values of minimum diurnal leaf water potential, leaf hydraulic conductance and functional vein density; and (c) maximum diurnal values of stomatal conductance to water vapour, transpiration rate and photosynthetic rate (An) were similar in both control leaves and the green areas of infested leaves. A strong reduction of An was recorded only in mined leaf areas. Our data suggest that infestation with P. citrella does not cause conspicuous plant productivity reductions in young Citrus plants, at least not in the three Citrus species studied here. PMID:24319027

  7. Distinct bacterial communities dominate tropical and temperate zone leaf litter.

    PubMed

    Kim, Mincheol; Kim, Woo-Sung; Tripathi, Binu M; Adams, Jonathan

    2014-05-01

    Little is known of the bacterial community of tropical rainforest leaf litter and how it might differ from temperate forest leaf litter and from the soils underneath. We sampled leaf litter in a similarly advanced stage of decay, and for comparison, we also sampled the surface layer of soil, at three tropical forest sites in Malaysia and four temperate forest sites in South Korea. Illumina sequencing targeting partial bacterial 16S ribosomal ribonucleic acid (rRNA) gene revealed that the bacterial community composition of both temperate and tropical litter is quite distinct from the soils underneath. Litter in both temperate and tropical forest was dominated by Proteobacteria and Actinobacteria, while soil is dominated by Acidobacteria and, to a lesser extent, Proteobacteria. However, bacterial communities of temperate and tropical litter clustered separately from one another on an ordination. The soil bacterial community structures were also distinctive to each climatic zone, suggesting that there must be a climate-specific biogeographical pattern in bacterial community composition. The differences were also found in the level of diversity. The temperate litter has a higher operational taxonomic unit (OTU) diversity than the tropical litter, paralleling the trend in soil diversity. Overall, it is striking that the difference in community composition between the leaf litter and the soil a few centimeters underneath is about the same as that between leaf litter in tropical and temperate climates, thousands of kilometers apart. However, one substantial difference was that the leaf litter of two tropical forest sites, Meranti and Forest Research Institute Malaysia (FRIM), was overwhelmingly dominated by the single genus Burkholderia, at 37 and 23 % of reads, respectively. The 454 sequencing result showed that most Burkholderia species in tropical leaf litter belong to nonpathogenic "plant beneficial" lineages. The differences from the temperate zone in the bacterial

  8. Ammonia emissions from deciduous forest after leaf fall

    NASA Astrophysics Data System (ADS)

    Hansen, K.; Sørensen, L. L.; Hertel, O.; Geels, C.; Skjøth, C. A.; Jensen, B.; Boegh, E.

    2013-07-01

    to atmospheric NH3 concentration from vegetative surfaces related to leaf fall are of a relatively large magnitude. We therefore conclude that emissions from deciduous forests are important to include in model calculations of atmospheric NH3 for forest ecosystems. Finally, diurnal variations in the measured NH3 concentrations were related to meteorological conditions, forest phenology and the spatial distribution of local anthropogenic NH3 sources. This suggests that an accurate description of ammonia fluxes over forest ecosystems requires a dynamic description of atmospheric and vegetation processes.

  9. Chloroplast Response to Low Leaf Water Potentials

    PubMed Central

    Keck, R. W.; Boyer, J. S.

    1974-01-01

    Cyclic and noncyclic photophosphorylation and electron transport by photosystem 1, photosystem 2, and from water to methyl viologen (“whole chain”) were studied in chloroplasts isolated from sunflower (Helianthus annus L. var Russian Mammoth) leaves that had been desiccated to varying degrees. Electron transport showed considerable inhibition at leaf water potentials of −9 bars when the chloroplasts were exposed to an uncoupler in vitro, and it continued to decline in activity as leaf water potentials decreased. Electron transport by photosystem 2 and coupled electron transport by photosystem 1 and the whole chain were unaffected at leaf water potentials of −10 to −11 bars but became progressively inhibited between leaf water potentials of −11 and −17 bars. A low, stable activity remained at leaf water potentials below −17 bars. In contrast, both types of photophosphorylation were unaffected by leaf water potentials of −10 to −11 bars, but then ultimately became zero at leaf water potentials of −17 bars. Although the chloroplasts isolated from the desiccated leaves were coupled at leaf water potentials of −11 to −12 bars, they became progressively uncoupled as leaf water potentials decreased to −17 bars. Abscisic acid and ribonuclease had no effect on chloroplast photophosphorylation. The results are generally consistent with the idea that chloroplast activity begins to decrease at the same leaf water potentials that cause stomatal closure in sunflower leaves and that chloroplast electron transport begins to limit photosynthesis at leaf water potentials below about −11 bars. However, it suggests that, during severe desiccation, the limitation may shift from electron transport to photophosphorylation. PMID:16658727

  10. Leaf hydraulic conductance in relation to anatomical and functional traits during Populus tremula leaf ontogeny.

    PubMed

    Aasamaa, Krõõt; Niinemets, Ulo; Sõber, Anu

    2005-11-01

    Leaf hydraulic conductance (K(leaf)) and several characteristics of hydraulic architecture and physiology were measured during the first 10 weeks of leaf ontogeny in Populus tremula L. saplings growing under control, mild water deficit or elevated temperature conditions. During the initial 3 weeks of leaf ontogeny, most measured characteristics rapidly increased. Thereafter, a gradual decrease in K(leaf) was correlated with a decrease in leaf osmotic potential under all conditions, and with increases in leaf dry mass per area and bulk modulus of elasticity under mild water deficit and control conditions. From about Week 3 onward, K(leaf) was 33% lower in trees subjected to mild water deficit and 33% higher in trees held at an elevated temperature relative to control trees. Mild water deficit and elevated temperature treatment had significant and opposite effects on most of the other characteristics measured. The ontogenetic maximum in K(leaf) was correlated positively with the width of xylem conduits in the midrib, but negatively with the overall width of the midrib xylem, number of lateral ribs, leaf dry mass per area and bulk modulus of elasticity. The ontogenetic maximum in K(leaf) was also correlated positively with the proportion of intercellular spaces and leaf osmotic potential, but negatively with leaf thickness, volume of mesophyll cells and epidermis and number of cells per total mesophyll cell volume, the closest relationships being between leaf osmotic potential and number of cells per total mesophyll cell volume. It was concluded that differences in protoplast traits are more important than differences in xylem or parenchymal cell wall traits in determining the variability in K(leaf) among leaves growing under different environmental conditions. PMID:16105808

  11. Machine vision guided sensor positioning system for leaf temperature assessment.

    PubMed

    Kim, Y; Ling, P P

    2001-01-01

    A sensor positioning system was developed for monitoring plants' well-being using a non-contact sensor. Image processing algorithms were developed to identify a target region on a plant leaf. A novel algorithm to recover view depth was developed by using a camera equipped with a computer-controlled zoom lens. The methodology has improved depth recovery resolution over a conventional monocular imaging technique. An algorithm was also developed to find a maximum enclosed circle on a leaf surface so the conical field-of-view of an infrared temperature sensor could be filled by the target without peripheral noise. The center of the enclosed circle and the estimated depth were used to define the sensor 3-D location for accurate plant temperature measurement. PMID:12088029

  12. Machine vision guided sensor positioning system for leaf temperature assessment

    NASA Technical Reports Server (NTRS)

    Kim, Y.; Ling, P. P.; Janes, H. W. (Principal Investigator)

    2001-01-01

    A sensor positioning system was developed for monitoring plants' well-being using a non-contact sensor. Image processing algorithms were developed to identify a target region on a plant leaf. A novel algorithm to recover view depth was developed by using a camera equipped with a computer-controlled zoom lens. The methodology has improved depth recovery resolution over a conventional monocular imaging technique. An algorithm was also developed to find a maximum enclosed circle on a leaf surface so the conical field-of-view of an infrared temperature sensor could be filled by the target without peripheral noise. The center of the enclosed circle and the estimated depth were used to define the sensor 3-D location for accurate plant temperature measurement.

  13. Host Phenology and Leaf Effects on Susceptibility of California Bay Laurel to Phytophthora ramorum.

    PubMed

    Johnston, Steven F; Cohen, Michael F; Torok, Tamas; Meentemeyer, Ross K; Rank, Nathan E

    2016-01-01

    Spread of the plant pathogen Phytophthora ramorum, causal agent of the forest disease sudden oak death, is driven by a few competent hosts that support spore production from foliar lesions. The relationship between traits of a principal foliar host, California bay laurel (Umbellularia californica), and susceptibility to P. ramorum infection were investigated with multiple P. ramorum isolates and leaves collected from multiple trees in leaf-droplet assays. We examined whether susceptibility varies with season, leaf age, or inoculum position. Bay laurel susceptibility was highest during spring and summer and lowest in winter. Older leaves (>1 year) were more susceptible than younger ones (8 to 11 months). Susceptibility was greater at leaf tips and edges than the middle of the leaf. Leaf surfaces wiped with 70% ethanol were more susceptible to P. ramorum infection than untreated leaf surfaces. Our results indicate that seasonal changes in susceptibility of U. californica significantly influence P. ramorum infection levels. Thus, in addition to environmental variables such as temperature and moisture, variability in host plant susceptibility contributes to disease establishment of P. ramorum. PMID:26439707

  14. Compensatory responses in plant-herbivore interactions: Impacts of insects on leaf water relations

    NASA Astrophysics Data System (ADS)

    Peschiutta, María L.; Bucci, Sandra J.; Scholz, Fabián G.; Goldstein, Guillermo

    2016-05-01

    Herbivore damage to leaves has been typically evaluated in terms of fractions of area removed; however morpho-physiological changes in the remaining tissues can occur in response to removal. We assessed the effects of partial removal of the leaf mesophyll by Caliroa cerasi (Hymenoptera) on leaf hydraulic conductance (Kleaf), vascular architecture, water relations and leaf size of three Prunus avium cultivars. The insect feeds on the leaf mesophyll leaving the vein network intact (skeletonization). Within each cultivar there were trees without infestations and trees chronically infested, at least over the last three years. Leaf size of intact leaves tended to be similar during leaf expansion before herbivore attack occurs across infested and non-infested trees. However, after herbivore attack and when the leaves were fully expanded, damaged leaves were smaller than leaves from non-infested trees. Damaged area varied between 21 and 31% depending on cultivar. The non-disruption of the vascular system together with either vein density or capacitance increased in damaged leaves resulted in similar Kleaf and stomatal conductance in infested and non-infested trees. Non-stomatal water loss from repeated leaf damage led to lower leaf water potentials in two of the infested cultivars. Lower leaf osmotic potentials and vulnerability to loss of Kleaf were observed in infested plants. Our results show that skeletonization resulted in compensatory changes in terms of water relations and hydraulics traits and in cultivar-specific physiological changes in phylogenetic related P. avium. Our findings indicate that detrimental effects of herbivory on the photosynthetic surface are counterbalanced by changes providing higher drought resistance, which has adaptive significance in ecosystems where water availability is low and furthermore where global climate changes would decrease soil water availability in the future even further.

  15. Microscopic Aspects of Silicon-Mediated Rice Resistance to Leaf Scald.

    PubMed

    Araujo, Leonardo; Paschoalino, Rayane Silva; Rodrigues, Fabrício Ávila

    2016-02-01

    This study investigated the effect of silicon (Si) on the potentiation of rice resistance against leaf scald at the microscopic level. Rice plants ('Primavera') were grown in a nutrient solution containing 0 (-Si) or 2 mM (+Si) Si. The foliar Si concentration of the +Si plants (3.6 dag/kg) increased in comparison with the -Si plants (0.3 dag/kg). An X-ray microanalysis revealed that the leaf tissue of +Si plants infected with Microdochium oryzae had higher peaks and deposition of insoluble Si than that of -Si plants. The high foliar Si concentration for the +Si plants reduced the expansion of leaf scald lesions. Scanning electron microscopy revealed that fungal hyphae and appressorium-like structures of M. oryzae were more abundant in the leaf surface of -Si plants relative to +Si plants. At both histopathological and ultrastructural levels, fungal hyphae grew abundantly into the leaf tissue of -Si plants. By contrast, rice cell walls were rarely degraded and fungal hyphae were often surrounded by amorphous granular material in the leaf tissue of +Si plants. Conidiophores emerged from stomata 36 h after fungal penetration, and conidia were noticed inside the leaf tissue of the -Si plants in great abundance. The collective results of the present study showed a high concentration and deposition of Si and a considerable deposition of phenolic-like compounds in the leaf tissue of +Si plants. These results indicate that the potentiation of the phenylpropanoid pathway in these plants supplied with Si was favorable for the increase in rice resistance to leaf scald. PMID:26237696

  16. Leaf blade anatomy and ultrastructure of six Simira species (Rubiaceae) from the Atlantic rain forest, Brazil.

    PubMed

    Moraes, Tarsila Maria da Silva; Barros, Claudia Franca; Silva Neto, Sebastião José; Gomes, Valdirene Moreira; Da Cunha, Maura

    2009-12-01

    Simira is a predominantly woody Neotropical genus comprising 41 taxa, 16 of which occur in Brazil and eight of them in the southeastern region of Brazil. Leaf blades of Simira eliezeriana Peixoto, S. glaziovii (K. Schum.) Steyem., S. grazielae Peixoto, S. pikia (K. Schum.) Steyerm., S. rubra (Mart.) Steyerm., S. sampaioana (Standl.) Steyerm. were collected in the southeastern region of Brazil and fixed according to usual methods for light and electron microscopy. The leaf blades show typical characteristics of the Rubiaceae family as dorsiventral mesophyll and paracytic stomata. The presence of two bundle sheaths that extend to the upper epidermal layer, prismatic crystal and crystal-sand, alkaloids in the mesophyll and the organization micromorphological of the outer periclinal wall are considered characteristics representative for the genus. This study also demonstrates some leaf blade characteristics that can be used to Simira species identification (leaf surface, domatia types, epicuticular wax types and patterns of epidermis anticlinal cell walls). PMID:20067031

  17. 7 CFR 29.2530 - Leaf structure.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...-Cured Tobacco (u.s. Types 22, 23, and Foreign Type 96) § 29.2530 Leaf structure. The cell development of... 7 Agriculture 2 2012-01-01 2012-01-01 false Leaf structure. 29.2530 Section 29.2530 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  18. 7 CFR 29.2278 - Leaf structure.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... structure. The cell development of a leaf as indicated by its porosity. (See chart, § 29.2351.) ... 7 Agriculture 2 2011-01-01 2011-01-01 false Leaf structure. 29.2278 Section 29.2278 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  19. 7 CFR 29.2530 - Leaf structure.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...-Cured Tobacco (u.s. Types 22, 23, and Foreign Type 96) § 29.2530 Leaf structure. The cell development of... 7 Agriculture 2 2013-01-01 2013-01-01 false Leaf structure. 29.2530 Section 29.2530 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  20. 7 CFR 29.2278 - Leaf structure.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... structure. The cell development of a leaf as indicated by its porosity. (See chart, § 29.2351.) ... 7 Agriculture 2 2013-01-01 2013-01-01 false Leaf structure. 29.2278 Section 29.2278 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  1. 7 CFR 29.2278 - Leaf structure.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... structure. The cell development of a leaf as indicated by its porosity. (See chart, § 29.2351.) ... 7 Agriculture 2 2012-01-01 2012-01-01 false Leaf structure. 29.2278 Section 29.2278 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  2. 7 CFR 29.2530 - Leaf structure.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ...-Cured Tobacco (u.s. Types 22, 23, and Foreign Type 96) § 29.2530 Leaf structure. The cell development of... 7 Agriculture 2 2011-01-01 2011-01-01 false Leaf structure. 29.2530 Section 29.2530 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  3. 7 CFR 29.2530 - Leaf structure.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...-Cured Tobacco (u.s. Types 22, 23, and Foreign Type 96) § 29.2530 Leaf structure. The cell development of... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf structure. 29.2530 Section 29.2530 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  4. 7 CFR 29.2278 - Leaf structure.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... structure. The cell development of a leaf as indicated by its porosity. (See chart, § 29.2351.) ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf structure. 29.2278 Section 29.2278 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  5. Evolutionary and Environmental Forces Sculpting Leaf Development.

    PubMed

    Chitwood, Daniel H; Sinha, Neelima R

    2016-04-01

    Leaf shape is spectacularly diverse. As a major component of plant architecture and an interface for light capture, gas exchange, and thermoregulation, the potential contributions of leaves to plant fitness are innumerable. Particularly because of their intimate association and interaction with the surrounding environment, both the plasticity of leaf shape during the lifetime of a plant and the evolution of leaf shape over geologic time are revealing with respect to leaf function. Leaf shapes arise within a developmental context that constrains both their evolution and environmental plasticity. Quantitative models capturing genetic diversity, developmental context, and environmental plasticity will be required to fully understand the evolution and development of leaf shape and its response to environmental pressures. In this review, we discuss recent literature demonstrating that distinct molecular pathways are modulated by specific environmental inputs, the output of which regulates leaf dissection. We propose a synthesis explaining both historical patterns in the paleorecord and conserved plastic responses in extant plants. Understanding the potential adaptive value of leaf shape, and how to molecularly manipulate it, will prove to be invaluable in designing crops optimized for future climates. PMID:27046820

  6. 7 CFR 29.1029 - Leaf scrap.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... Type 92) § 29.1029 Leaf scrap. A byproduct of stemmed and unstemmed tobacco. ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf scrap. 29.1029 Section 29.1029 Agriculture... Practices), DEPARTMENT OF AGRICULTURE COMMODITY STANDARDS AND STANDARD CONTAINER REGULATIONS...

  7. An Exploration of Distributed Leaf Wetness and Dew Detection Using Inexpensive Radios

    NASA Astrophysics Data System (ADS)

    Niemeier, J. J.; Rowlandson, T. L.; Kruger, A.; Hornbuckle, B. K.

    2009-12-01

    Our understanding of latent heat transfer between the soil surface and canopy is not complete. A major contributing factor to the uncertainty is the presence and amount of dew on the plant canopy. Improved measurements of dew duration, and possibly amount would help refine land surface process models. There are automated leaf wetness sensors available that consist of a simple sensor that attempts to simulate a single leaf. The electrical resistivity of the sensor is a function of the amount of liquid water that has condensed on its surface. These sensors generally provide reliable dew/no dew indication, but do not provide good information on dew amount. It may be possible to obtain dew amount from such sensors, but that would require careful calibration, because of the nonlinear relationship between dew amount and resistivity. The alternative is traditional measurements that require manually sampling and measuring dew amount. This latter is time-consuming and labor-intensive. Further, all these methods are point measurements that suffer from sampling errors. We are exploring the use of very inexpensive radios that operate in the unlicensed industrial, scientific, and medical (ISM) band as leaf wetness sensors. Our hypothesis is that dew on plant leafs attenuates the radio signals, and by recording the received signal strength, one can detect changes in leaf wetness. Further, such measurements are distributed/volume measurements that counter sampling errors inherent in point measurements. By using directional antennas, there is the exciting possibility to perform tomographic dew measurements. To test our hypothesis, we have deployed a number of radios operating at 2.4 GHz and 900 MHz, collocated with traditional leaf-wetness sensors in a corn field near Ames, Iowa. We have also made a large number of traditional leaf wetness/dew amount measurements at this location. Preliminary data analysis for the radio-based technique is promising. In this work, we present and

  8. Possible Roles of Strigolactones during Leaf Senescence

    PubMed Central

    Yamada, Yusuke; Umehara, Mikihisa

    2015-01-01

    Leaf senescence is a complicated developmental process that involves degenerative changes and nutrient recycling. The progress of leaf senescence is controlled by various environmental cues and plant hormones, including ethylene, jasmonic acid, salicylic acid, abscisic acid, cytokinins, and strigolactones. The production of strigolactones is induced in response to nitrogen and phosphorous deficiency. Strigolactones also accelerate leaf senescence and regulate shoot branching and root architecture. Leaf senescence is actively promoted in a nutrient-poor soil environment, and nutrients are transported from old leaves to young tissues and seeds. Strigolactones might act as important signals in response to nutrient levels in the rhizosphere. In this review, we discuss the possible roles of strigolactones during leaf senescence. PMID:27135345

  9. Inferring climate from angiosperm leaf venation networks.

    PubMed

    Blonder, Benjamin; Enquist, Brian J

    2014-10-01

    Leaf venation networks provide an integrative linkage between plant form, function and climate niche, because leaf water transport underlies variation in plant performance. Here, we develop theory based on leaf physiology that uses community-mean vein density to predict growing season temperature and atmospheric CO2 concentration. The key assumption is that leaf water supply is matched to water demand in the local environment. We test model predictions using leaves from 17 temperate and tropical sites that span broad climatic gradients. We find quantitative agreement between predicted and observed climate values. We also highlight additional leaf traits that may improve predictions. Our study provides a novel approach for understanding the functional linkages between functional traits and climate that may improve the reconstruction of paleoclimate from fossil assemblages. PMID:24725225

  10. Leaf hydraulic conductivity and stomatal responses to humidity in amphistomatous leaves.

    PubMed

    Mott, Keith A

    2007-11-01

    The response of stomata to changes in humidity for a single surface of an amphistomatous leaf was investigated in Xanthium strumarium and Vicia faba using gas exchange and direct observation of stomatal apertures. The stomatal response to humidity for a given surface was found to be the same whether or not the humidity for the opposite surface was changed concurrently. Stomata on the surface for which humidity was constant showed no response to changes in humidity for the opposite surface. Despite large changes in epidermal turgor on the surface for which humidity was changed, there was no change in epidermal turgor for the surface with constant humidity. Measurements of transpiration and epidermal turgor as functions of the mole fraction gradient of water between leaf and air were used to calculate a value for leaf hydraulic resistance. The results suggest that in these species, the mechanism for the stomatal response to humidity resides in the epidermis or the mesophyll very close to the epidermis, and that most of the hydraulic resistance of the leaf occurs between the xylem and the evaporating sites. PMID:17897414

  11. Relating Stomatal Conductance to Leaf Functional Traits

    PubMed Central

    Kröber, Wenzel; Plath, Isa; Heklau, Heike; Bruelheide, Helge

    2015-01-01

    Leaf functional traits are important because they reflect physiological functions, such as transpiration and carbon assimilation. In particular, morphological leaf traits have the potential to summarize plants strategies in terms of water use efficiency, growth pattern and nutrient use. The leaf economics spectrum (LES) is a recognized framework in functional plant ecology and reflects a gradient of increasing specific leaf area (SLA), leaf nitrogen, phosphorus and cation content, and decreasing leaf dry matter content (LDMC) and carbon nitrogen ratio (CN). The LES describes different strategies ranging from that of short-lived leaves with high photosynthetic capacity per leaf mass to long-lived leaves with low mass-based carbon assimilation rates. However, traits that are not included in the LES might provide additional information on the species' physiology, such as those related to stomatal control. Protocols are presented for a wide range of leaf functional traits, including traits of the LES, but also traits that are independent of the LES. In particular, a new method is introduced that relates the plants’ regulatory behavior in stomatal conductance to vapor pressure deficit. The resulting parameters of stomatal regulation can then be compared to the LES and other plant functional traits. The results show that functional leaf traits of the LES were also valid predictors for the parameters of stomatal regulation. For example, leaf carbon concentration was positively related to the vapor pressure deficit (vpd) at the point of inflection and the maximum of the conductance-vpd curve. However, traits that are not included in the LES added information in explaining parameters of stomatal control: the vpd at the point of inflection of the conductance-vpd curve was lower for species with higher stomatal density and higher stomatal index. Overall, stomata and vein traits were more powerful predictors for explaining stomatal regulation than traits used in the LES

  12. Cross-scale modelling of transpiration from stomata via the leaf boundary layer

    PubMed Central

    Defraeye, Thijs; Derome, Dominique; Verboven, Pieter; Carmeliet, Jan; Nicolai, Bart

    2014-01-01

    Background and Aims Leaf transpiration is a key parameter for understanding land surface–climate interactions, plant stress and plant structure–function relationships. Transpiration takes place at the microscale level, namely via stomata that are distributed discretely over the leaf surface with a very low surface coverage (approx. 0·2–5 %). The present study aims to shed more light on the dependency of the leaf boundary-layer conductance (BLC) on stomatal surface coverage and air speed. Methods An innovative three-dimensional cross-scale modelling approach was applied to investigate convective mass transport from leaves, using computational fluid dynamics. The gap between stomatal and leaf scale was bridged by including all these scales in the same computational model (10−5–10−1 m), which implies explicitly modelling individual stomata. Key Results BLC was strongly dependent on stomatal surface coverage and air speed. Leaf BLC at low surface coverage ratios (CR), typical for stomata, was still relatively high, compared with BLC of a fully wet leaf (hypothetical CR of 100 %). Nevertheless, these conventional BLCs (CR of 100 %), as obtained from experiments or simulations on leaf models, were found to overpredict the convective exchange. In addition, small variations in stomatal CR were found to result in large variations in BLCs. Furthermore, stomata of a certain size exhibited a higher mass transfer rate at lower CRs. Conclusions The proposed cross-scale modelling approach allows us to increase our understanding of transpiration at the sub-leaf level as well as the boundary-layer microclimate in a way currently not feasible experimentally. The influence of stomatal size, aperture and surface density, and also flow-field parameters can be studied using the model, and prospects for further improvement of the model are presented. An important conclusion of the study is that existing measures of conductances (e.g. from artificial leaves) can be

  13. A model for leaf initiation

    PubMed Central

    Abraham-Shrauner, Barbara; Pickard, Barbara G

    2011-01-01

    A biophysical model is proposed for how leaf primordia are positioned on the shoot apical
    meristem in both spiral and whorl phyllotaxes. Primordia are initiated by signals that propagate
    in the epidermis in both azimuthal directions away from the cotyledons or the most recently
    specified primordia. The signals are linear waves as inferred from the spatial periodicity of the
    divergence angle and a temporal periodicity. The periods of the waves, which represent actively
    transported auxin, are much smaller than the plastochron interval. Where oppositely directed
    waves meet at one or more angular positions on the periphery of the generative circle, auxin
    concentration builds and as in most models this stimulates local movement of auxin to
    underlying cells, where it promotes polarized cell division and expansion. For higher order
    spirals the wave model requires asymmetric function of auxin transport; that is, opposite wave
    speeds differ. An algorithm for determination of the angular positions of leaves in common leaf
    phyllotaxic configurations is proposed. The number of turns in a pattern repeat, number of leaves
    per level and per pattern repeat, and divergence angle are related to speed of auxin transport and
    radius of the generative circle. The rule for composition of Fibonacci or Lucas numbers
    associated with some phyllotaxes is discussed. A subcellular model suggests how the shoot
    meristem might specify either symmetric or asymmetric transport of auxin away from the
    forming primordia that produce it. Biological tests that could make or break the mathematical
    and molecular hypotheses are proposed. PMID:22212121

  14. Applicability of non-destructive substitutes for leaf area in different stands of Norway spruce (Picea abies L. Karst.) focusing on traditional forest crown measures

    PubMed Central

    Laubhann, Daniel; Eckmüllner, Otto; Sterba, Hubert

    2010-01-01

    Since individual tree leaf area is an important measure for productivity as well as for site occupancy, it is of high interest in many studies about forest growth. The exact determination of leaf area is nearly impossible. Thus, a common way to get information about leaf area is to use substitutes. These substitutes are often variables which are collected in a destructive way which is not feasible for long term studies. Therefore, this study aimed at testing the applicability of using substitutes for leaf area which could be collected in a non-destructive way, namely crown surface area and crown projection area. In 8 stands of Norway spruce (Picea abies L. Karst.), divided into three age classes and two thinning treatments, a total of 156 trees were felled in order to test the relationship between leaf area and crown surface area and crown projection area, respectively. Individual tree leaf area of the felled sample trees was estimated by 3P-branch sampling with an accuracy of ±10%. Crown projection area and crown surface area were compared with other, more commonly used, but destructive predictors of leaf area, namely sapwood area at different heights on the bole. Our investigations confirmed findings of several studies that sapwood area is the most precise measure for leaf area because of the high correlation between sapwood area and the leaf area. But behind sapwood area at crown base and sapwood area at three tenth of the tree height the predictive ability of crown surface area was ranked third and even better than that of sapwood area at breast height (R2 = 0.656 compared with 0.600). Within the stands leaf area is proportional to crown surface area. Using the pooled data of all stands a mixed model approach showed that additionally to crown surface area dominant height and diameter at breast height (dbh) improved the leaf area estimates. Thus, taking dominant height and dbh into account, crown surface area can be recommended for estimating the leaf area of

  15. Characterization of Leaf Blade- and Leaf Sheath-Associated Bacterial Communities and Assessment of Their Responses to Environmental Changes in CO2, Temperature, and Nitrogen Levels under Field Conditions

    PubMed Central

    Ikeda, Seishi; Tokida, Takeshi; Nakamura, Hirofumi; Sakai, Hidemitsu; Usui, Yasuhiro; Okubo, Takashi; Tago, Kanako; Hayashi, Kentaro; Sekiyama, Yasuyo; Ono, Hiroshi; Tomita, Satoru; Hayatsu, Masahito; Hasegawa, Toshihiro; Minamisawa, Kiwamu

    2015-01-01

    Rice shoot-associated bacterial communities at the panicle initiation stage were characterized and their responses to elevated surface water-soil temperature (ET), low nitrogen (LN), and free-air CO2 enrichment (FACE) were assessed by clone library analyses of the 16S rRNA gene. Principal coordinate analyses combining all sequence data for leaf blade- and leaf sheath-associated bacteria revealed that each bacterial community had a distinct structure, as supported by PC1 (61.5%), that was mainly attributed to the high abundance of Planctomycetes in leaf sheaths. Our results also indicated that the community structures of leaf blade-associated bacteria were more sensitive than those of leaf sheath-associated bacteria to the environmental factors examined. Among these environmental factors, LN strongly affected the community structures of leaf blade-associated bacteria by increasing the relative abundance of Bacilli. The most significant effect of FACE was also observed on leaf blade-associated bacteria under the LN condition, which was explained by decreases and increases in Agrobacterium and Pantoea, respectively. The community structures of leaf blade-associated bacteria under the combination of FACE and ET were more similar to those of the control than to those under ET or FACE. Thus, the combined effects of environmental factors need to be considered in order to realistically assess the effects of environmental changes on microbial community structures. PMID:25740174

  16. Antimicrobial effect of Pistacia atlantica leaf extract

    PubMed Central

    Ali Roozegar, Mohamad; Azizi Jalilian, Farid; Reza Havasian, Mohamad; Panahi, Jafar; Pakzad, Iraj

    2016-01-01

    The antimicrobial effect of the mastic tree (Pistacia atlantica) under in vitro conditions has been reported. Therefore, it is of interest to evaluate the effect of the plant leaf extract (aqueous) on bacterial load in mouth and saliva. The leaf of the Pistacia atlantica plant was collected and cleaned, dried at 40⁰c and then powdered. The extraction was carried out using the maceration method in vacuum with the rotary evaporator device. Bacterial inhibition (Streptococcus species) by the leaf extract was studied using the disc diffusion and embedding sink diffusion methods. The values of MIC and MBC were determined. The collected data was further analyzed using t-test and repeated measure statistical tests. The disc diffusion technique showed a significant inhibitory effect for Pistacia atlantica leaf extract on S. mutans (ATCC 35668) and S. mitis (ATCC 49456) with inhibition zones of 19 and 25 millimeters, respectively. This is for the highest leaf extract concentration used in this study (p<0.01). The values of MIC and MBC for S.mutans was 60, 90 μg/ml and for S. mitis was 75, 110 μg/ml (p<0.01 significance). The leaf extract has no significant effect on S. salivarius (ATCC 13419). Thus, the antimicrobial properties of the aqueous leaf extract from Pistacia atlantica is demonstrated in this study. PMID:27212840

  17. Leaf wetness distribution within a potato crop

    NASA Astrophysics Data System (ADS)

    Heusinkveld, B. G.

    2010-07-01

    The Netherlands has a mild maritime climate and therefore the major interest in leaf wetness is associated with foliar plant diseases. During moist micrometeorological conditions (i.e. dew, fog, rain), foliar fungal diseases may develop quickly and thereby destroy a crop quickly. Potato crop monocultures covering several hectares are especially vulnerable to such diseases. Therefore understanding and predicting leaf wetness in potato crops is crucial in crop disease control strategies. A field experiment was carried out in a large homogeneous potato crop in the Netherlands during the growing season of 2008. Two innovative sensor networks were installed as a 3 by 3 grid at 3 heights covering an area of about 2 hectares within two larger potato crops. One crop was located on a sandy soil and one crop on a sandy peat soil. In most cases leaf wetting starts in the top layer and then progresses downward. Leaf drying takes place in the same order after sunrise. A canopy dew simulation model was applied to simulate spatial leaf wetness distribution. The dew model is based on an energy balance model. The model can be run using information on the above-canopy wind speed, air temperature, humidity, net radiation and within canopy air temperature, humidity and soil moisture content and temperature conditions. Rainfall was accounted for by applying an interception model. The results of the dew model agreed well with the leaf wetness sensors if all local conditions were considered. The measurements show that the spatial correlation of leaf wetness decreases downward.

  18. Lipidomics of tobacco leaf and cigarette smoke.

    PubMed

    Dunkle, Melissa N; Yoshimura, Yuta; t'Kindt, Ruben; Ortiz, Alexia; Masugi, Eri; Mitsui, Kazuhisa; David, Frank; Sandra, Pat; Sandra, Koen

    2016-03-25

    Detailed lipidomics experiments were performed on the extracts of cured tobacco leaf and of cigarette smoke condensate (CSC) using high-resolution liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (LC-Q-TOF MS). Following automated solid-phase extraction (SPE) fractionation of the lipid extracts, over 350 lipids could be annotated. From a large-scale study on 22 different leaf samples, it was determined that differentiation based on curing type was possible for both the tobacco leaf and the CSC extracts. Lipids responsible for the classification were identified and the findings were correlated to proteomics data acquired from the same tobacco leaf samples. Prediction models were constructed based on the lipid profiles observed in the 22 leaf samples and successfully allowed for curing type classification of new tobacco leaves. A comparison of the leaf and CSC data provided insight into the lipidome changes that occur during the smoking process. It was determined that lipids which survive the smoking process retain the same curing type trends in both the tobacco leaf and CSC data. PMID:26585203

  19. Antimicrobial effect of Pistacia atlantica leaf extract.

    PubMed

    Ali Roozegar, Mohamad; Azizi Jalilian, Farid; Reza Havasian, Mohamad; Panahi, Jafar; Pakzad, Iraj

    2016-01-01

    The antimicrobial effect of the mastic tree (Pistacia atlantica) under in vitro conditions has been reported. Therefore, it is of interest to evaluate the effect of the plant leaf extract (aqueous) on bacterial load in mouth and saliva. The leaf of the Pistacia atlantica plant was collected and cleaned, dried at 40⁰c and then powdered. The extraction was carried out using the maceration method in vacuum with the rotary evaporator device. Bacterial inhibition (Streptococcus species) by the leaf extract was studied using the disc diffusion and embedding sink diffusion methods. The values of MIC and MBC were determined. The collected data was further analyzed using t-test and repeated measure statistical tests. The disc diffusion technique showed a significant inhibitory effect for Pistacia atlantica leaf extract on S. mutans (ATCC 35668) and S. mitis (ATCC 49456) with inhibition zones of 19 and 25 millimeters, respectively. This is for the highest leaf extract concentration used in this study (p<0.01). The values of MIC and MBC for S.mutans was 60, 90 μg/ml and for S. mitis was 75, 110 μg/ml (p<0.01 significance). The leaf extract has no significant effect on S. salivarius (ATCC 13419). Thus, the antimicrobial properties of the aqueous leaf extract from Pistacia atlantica is demonstrated in this study. PMID:27212840

  20. Validating LiDAR Derived Estimates of Canopy Height, Structure and Fractional Cover in Riparian Areas: A Comparison of Leaf-on and Leaf-off LiDAR Data

    NASA Astrophysics Data System (ADS)

    Wasser, L. A.; Chasmer, L. E.; Taylor, A.; Day, R.

    2010-12-01

    Characterization of riparian buffers is integral to understanding the landscape scale impacts of disturbance on wildlife and aquatic ecosystems. Riparian buffers may be characterized using in situ plot sampling or via high resolution remote sensing. Field measurements are time-consuming and may not cover a broad range of ecosystem types. Further, spectral remote sensing methods introduce a compromise between spatial resolution (grain) and area extent. Airborne LiDAR can be used to continuously map and characterize riparian vegetation structure and composition due to the three-dimensional reflectance of laser pulses within and below the canopy, understory and at the ground surface. The distance between reflections (or ‘returns’) allows for detection of narrow buffer corridors at the landscape scale. There is a need to compare leaf-off and leaf-on surveyed LiDAR data with in situ measurements to assess accuracy in landscape scale analysis. These comparisons are particularly important considering increased availability of leaf-off surveyed LiDAR datasets. And given this increased availability, differences between leaf-on and leaf-off derived LiDAR metrics are largely unknown for riparian vegetation of varying composition and structure. This study compares the effectiveness of leaf-on and leaf-off LiDAR in characterizing riparian buffers of varying structure and composition as compared to field measurements. Field measurements were used to validate LiDAR derived metrics. Vegetation height, canopy cover, density and overstory and understory species composition were recorded in 80 random plots of varying vegetation type, density and structure within a Pennsylvania watershed (-77.841, 40.818). Plot data were compared with LiDAR data collected during leaf on and leaf off conditions to determine 1) accuracy of LiDAR derived metrics compared to field measures and 2) differences between leaf-on and leaf-off LiDAR metrics. Results illustrate that differences exist between

  1. Preliminary validation of leaf area index sensor in Huailai

    NASA Astrophysics Data System (ADS)

    Cai, Erli; Li, Xiuhong; Liu, Qiang; Dou, Baocheng; Chang, Chongyan; Niu, Hailin; Lin, Xingwen; Zhang, Jialin

    2015-12-01

    Leaf area index (LAI) is a key variable in many land surface models that involve energy and mass exchange between vegetation and the environment. In recent years, extracting vegetation structure parameters from digital photography becomes a widely used indirect method to estimate LAI for its simplicity and ease of use. A Leaf Area Index Sensor (LAIS) system was developed to continuously monitor the growth of crops in several sampling points in Huailai, China. The system applies 3G/WIFI communication technology to remotely collect crop photos in real-time. Then the crop photos are automatically processed and LAI is estimated based on the improved leaf area index of Lang and Xiang (LAILX) algorithm in LAIS. The objective of this study is to primarily verify the LAI estimated from LAIS (Lphoto) through comparing them with the destructive green LAI (Ldest). Ldest was measured across the growing season ntil maximum canopy development while plants are still green. The preliminary verification shows that Lphoto corresponds well with the Ldest (R2=0.975). In general, LAI could be accurately estimated with LAIS and its LAI shows high consistency compared with the destructive green LAI. The continuous LAI measurement obtained from LAIS could be used for the validation of remote sensing LAI products.

  2. Leaf Epicuticular Waxes of the Eceriferum Mutants in Arabidopsis.

    PubMed Central

    Jenks, M. A.; Tuttle, H. A.; Eigenbrode, S. D.; Feldmann, K. A.

    1995-01-01

    Wild-type Arabidopsis leaf epicuticular wax (EW) occurs as a smooth layer over the epidermal surface, whereas stem EW has a crystalline microstructure. Wild-type EW load was more than 10-fold lower on leaves than on stems. Compared with the EW on wild-type stems, EW on wild-type leaves had a much higher proportion of their total EW load in the form of alkanes and 1-alcohols; a large reduction in secondary alcohols, ketones, and esters; and a chain-length distribution for major EW classes that was skewed toward longer lengths. The eceriferum (cer) mutations often differentially affected leaf and stem EW chemical compositions. For example, the cer2 mutant EW phenotype was expressed on the stem but not on the leaf. Compared to wild type, the amount of primary alcohols on cer9 mutants was reduced on leaves but elevated on stems, whereas an opposite differential effect for primary alcohols was observed on cer16 leaves and stems. Putative functions for CER gene products are discussed. The CER4 and CER6 gene products may be involved in fatty aldehyde reduction and C26 fatty acylcoenzyme A elongation, respectively. CER1, CER8, CER9, and CER16 gene products may be involved in EW substrate transfer. The CER3 gene product may be involved in release of fatty acids from elongase complexes. CER2 gene product may have regulatory functions. PMID:12228482

  3. Lifting Entry & Atmospheric Flight (LEAF) Applications at Solar System Bodies.

    NASA Astrophysics Data System (ADS)

    Lee, G.; Sen, B.; Polidan, R. S.

    2015-12-01

    Introduction: Northrop Grumman and L'Garde have continued the development of a hypersonic entry, maneuverable platform capable of performing long-duration (months to a year) in situ and remote measurements at any solar system body that possesses an atmosphere. The Lifting Entry & Atmospheric Flight (LEAF) family of vehicles achieve this capability by using a semi-buoyant, ultra-low ballistic coefficient vehicle whose lifting entry allows it to enter the atmosphere without an aeroshell. In this presentation, we discuss the application of the LEAF system at various solar system bodies: Venus, Titan, Mars, and Earth. We present the key differences in platform design as well as operational differences required by the various target environments. The Venus implementation includes propulsive capability to reach higher altitudes during the day and achieves full buoyancy in the "habitable layers" of Venus' atmosphere at night. Titan also offers an attractive operating environment, allowing LEAF designs that can target low, medium, or high altitude operations, also with propulsive capabilities to roam within each altitude regime. The Mars version is a glider that descends gradually, allowing targeted delivery of payloads to the surface. Finally, an Earth version could remain in orbit in a stowed state until activated, allowing rapid response type deployments to any region of the globe.

  4. Global Climatic Controls On Leaf Size

    NASA Astrophysics Data System (ADS)

    Wright, I. J.; Prentice, I. C.; Dong, N.; Maire, V.

    2015-12-01

    Since the 1890s it's been known that the wet tropics harbour plants with exceptionally large leaves. Yet the observed latitudinal gradient of leaf size has never been fully explained: it is still unclear which aspects of climate are most important for understanding geographic trends in leaf size, a trait that varies many thousand-fold among species. The key is the leaf-to-air temperature difference, which depends on the balance of energy inputs (irradiance) and outputs (transpirational cooling, losses to the night sky). Smaller leaves track air temperatures more closely than larger leaves. Widely cited optimality-based theories predict an advantage for smaller leaves in dry environments, where transpiration is restricted, but are silent on the latitudinal gradient. We aimed to characterize and explain the worldwide pattern of leaf size. Across 7900 species from 651 sites, here we show that: large-leaved species predominate in wet, hot, sunny environments; smaller-leaved species typify hot, sunny environments only when arid; small leaves are required to avoid freezing in high latitudes and at high elevation, and to avoid overheating in dry environments. This simple pattern was unclear in earlier, more limited analyses. We present a simple but robust, fresh approach to energy-balance modelling for both day-time and night-time leaf-to-air temperature differences, and thus risk of overheating and of frost damage. Our analysis shows night-chilling is important as well as day-heating, and simplifies leaf temperature modelling. It provides both a framework for modelling leaf size constraints, and a solution to one of the oldest conundrums in ecology. Although the path forward is not yet fully clear, because of its role in controlling leaf temperatures we suggest that climate-related leaf size constraints could usefully feature in the next generation of land ecosystem models.

  5. Foliar micromorphology of Felicia muricata Thunb., A South African medicinal plant.

    PubMed

    Ashafa, A O T; Grierson, D S; Afolayan, A J

    2008-07-01

    The foliar micromorphology of Felicia muricata (Thunb.) Nees (Asteraceae) was observed with the JEOL (JSM-6390LV) Scanning Electron Microscope (SEM). Both the abaxial and adaxial surfaces were characterized by anisocytic stomata which were more prevalent on the abaxial surface than the adaxial surface. The leaves have only one type of multicellular non-glandular trichomes that are long and cylindrical, tapering to a sharp point and running parallel to the leaf surface in the direction of the apices. Crystal deposits were also observed on the surfaces of the leaves near the stomata. Energy dispersive X-ray spectroscopy-SEM shows that Na, Al, Si, and K were the major constituents of the crystal analyzed. Since no glandular trichomes were present on the leaves of this herb, the bioactive components present in this plant may be produced in some other tissues in the leaf other than the trichomes. PMID:18819624

  6. On the concept of leaf boundary layer resistance for forced convection

    PubMed

    Vesala

    1998-09-01

    The definition of leaf boundary layer resistance is reconsidered in respect of the three-dimensional diffusion-controlled mass transport region just above the leaf surface. Due to the existence of this superstomatal air layer, the conventional convective boundary layer is not in direct contact with the surface. Thus, in terms of plant physiology, the diffusive "end correction" to the stomatal resistance should be included in the boundary layer resistance. This is true for laminar as well as turbulent flows. When the surface mole fraction of an exchanged gas is estimated using the boundary layer resistance ignoring the diffusive term may lead to a noticeable error. The self-consistent approach is used to clarify the problems of the boundary layer formation and stomatal interference. If the correction is taken into account, the boundary layer resistance becomes dependent also on stomatal shape and distribution on the leaf. The traditional semiempirical formula corrected by the superstomatal diffusion is applied in numerical calculations. In estimates of the water vapour mole fraction on the surface of a transpiring leaf the relative error ranges from insignificant (quiescent air, large leaf and large stomatal pores) to 20 % (low humidity, strong wind, small leaf and small elliptic pores). The boundary layer resistance can decrease by a factor of 3 when the semiaxis lengths of the stomata increase from 1 and 0.5 &mgr;m to 10 and 5 &mgr;m. The effective thickness of the superstomatal air layer is maximally several millimetres (small stomatal surface concentration and small pores). Copyright 1998 Academic Press Limited PMID:9778427

  7. Can biomass responses to warming at plant to ecosystem levels be predicted by leaf-level responses?

    NASA Astrophysics Data System (ADS)

    Xia, J.; Shao, J.; Zhou, X.; Yan, W.; Lu, M.

    2015-12-01

    Global warming has the profound impacts on terrestrial C processes from leaf to ecosystem scales, potentially feeding back to climate dynamics. Although numerous studies had investigated the effects of warming on C processes from leaf to plant and ecosystem levels, how leaf-level responses to warming scale up to biomass responses at plant, population, and community levels are largely unknown. In this study, we compiled a dataset from 468 papers at 300 experimental sites and synthesized the warming effects on leaf-level parameters, and plant, population and ecosystem biomass. Our results showed that responses of plant biomass to warming mainly resulted from the changed leaf area rather than the altered photosynthetic capacity. The response of ecosystem biomass to warming was weaker than those of leaf area and plant biomass. However, the scaling functions from responses of leaf area to plant biomass to warming were different in diverse forest types, but functions were similar in non-forested biomes. In addition, it is challenging to scale the biomass responses from plant up to ecosystem. These results indicated that leaf area might be the appropriate index for plant biomass response to warming, and the interspecific competition might hamper the scaling of the warming effects on plant and ecosystem levels, suggesting that the acclimation capacity of plant community should be incorporated into land surface models to improve the prediction of climate-C cycle feedback.

  8. Quantitative phenotyping of leaf margins in three dimensions, demonstrated on KNOTTED and TCP trangenics in Arabidopsis

    PubMed Central

    Sharon, Eran

    2014-01-01

    The geometry of leaf margins is an important shape characteristic that distinguishes among different leaf phenotypes. Current definitions of leaf shape are qualitative and do not allow quantification of differences in shape between phenotypes. This is especially true for leaves with some non-trivial three-dimensional (3D) configurations. Here we present a novel geometrical method novel geometrical methods to define, measure, and quantify waviness and lobiness of leaves. The method is based on obtaining the curve of the leaf rim from a 3D surface measurement and decomposing its local curvature vector into the normal and geodesic components. We suggest that leaf waviness is associated with oscillating normal curvature along the margins, while lobiness is associated with oscillating geodesic curvature. We provide a way to integrate these local measures into global waviness and lobiness quantities. Using these novel definitions, we analysed the changes in leaf shape of two Arabidopsis genotypes, either as a function of gene mis-expression induction level or as a function of time. These definitions and experimental methods open the way for a more quantitative study of the shape of leaves and other growing slender organs. PMID:24706720

  9. Impact of plant shoot architecture on leaf cooling: a coupled heat and mass transfer model

    PubMed Central

    Bridge, L. J.; Franklin, K. A.; Homer, M. E.

    2013-01-01

    Plants display a range of striking architectural adaptations when grown at elevated temperatures. In the model plant Arabidopsis thaliana, these include elongation of petioles, and increased petiole and leaf angles from the soil surface. The potential physiological significance of these architectural changes remains speculative. We address this issue computationally by formulating a mathematical model and performing numerical simulations, testing the hypothesis that elongated and elevated plant configurations may reflect a leaf-cooling strategy. This sets in place a new basic model of plant water use and interaction with the surrounding air, which couples heat and mass transfer within a plant to water vapour diffusion in the air, using a transpiration term that depends on saturation, temperature and vapour concentration. A two-dimensional, multi-petiole shoot geometry is considered, with added leaf-blade shape detail. Our simulations show that increased petiole length and angle generally result in enhanced transpiration rates and reduced leaf temperatures in well-watered conditions. Furthermore, our computations also reveal plant configurations for which elongation may result in decreased transpiration rate owing to decreased leaf liquid saturation. We offer further qualitative and quantitative insights into the role of architectural parameters as key determinants of leaf-cooling capacity. PMID:23720538

  10. Leaf nitrogen and phosphorus of temperate desert plants in response to climate and soil nutrient availability

    PubMed Central

    He, Mingzhu; Dijkstra, Feike A.; Zhang, Ke; Li, Xinrong; Tan, Huijuan; Gao, Yanhong; Li, Gang

    2014-01-01

    In desert ecosystems, plant growth and nutrient uptake are restricted by availability of soil nitrogen (N) and phosphorus (P). The effects of both climate and soil nutrient conditions on N and P concentrations among desert plant life forms (annual, perennial and shrub) remain unclear. We assessed leaf N and P levels of 54 desert plants and measured the corresponding soil N and P in shallow (0–10 cm), middle (10–40 cm) and deep soil layers (40–100 cm), at 52 sites in a temperate desert of northwest China. Leaf P and N:P ratios varied markedly among life forms. Leaf P was higher in annuals and perennials than in shrubs. Leaf N and P showed a negative relationship with mean annual temperature (MAT) and no relationship with mean annual precipitation (MAP), but a positive relationship with soil P. Leaf P of shrubs was positively related to soil P in the deep soil. Our study indicated that leaf N and P across the three life forms were influenced by soil P. Deep-rooted plants may enhance the availability of P in the surface soil facilitating growth of shallow-rooted life forms in this N and P limited system, but further research is warranted on this aspect. PMID:25373739

  11. Quantitative phenotyping of leaf margins in three dimensions, demonstrated on KNOTTED and TCP trangenics in Arabidopsis.

    PubMed

    Armon, Shahaf; Yanai, Osnat; Ori, Naomi; Sharon, Eran

    2014-05-01

    The geometry of leaf margins is an important shape characteristic that distinguishes among different leaf phenotypes. Current definitions of leaf shape are qualitative and do not allow quantification of differences in shape between phenotypes. This is especially true for leaves with some non-trivial three-dimensional (3D) configurations. Here we present a novel geometrical method novel geometrical methods to define, measure, and quantify waviness and lobiness of leaves. The method is based on obtaining the curve of the leaf rim from a 3D surface measurement and decomposing its local curvature vector into the normal and geodesic components. We suggest that leaf waviness is associated with oscillating normal curvature along the margins, while lobiness is associated with oscillating geodesic curvature. We provide a way to integrate these local measures into global waviness and lobiness quantities. Using these novel definitions, we analysed the changes in leaf shape of two Arabidopsis genotypes, either as a function of gene mis-expression induction level or as a function of time. These definitions and experimental methods open the way for a more quantitative study of the shape of leaves and other growing slender organs. PMID:24706720

  12. The effect of leaf size on the microwave backscattering by corn

    NASA Technical Reports Server (NTRS)

    Paris, J. F.

    1986-01-01

    Attema and Ulaby (1978) proposed the cloud model to predict the microwave backscattering properties of vegetation. This paper describes a modification in which the biophysical properties and microwave properties of vegetation are related at the level of the individual scatterer (e.g., the leaf or the stalk) rather than at the level of the aggregated canopy (e.g., the green leaf area index). Assuming that the extinction cross section of an average leaf was proportional to its water content, that a power law relationship existed between the backscattering cross section of an average green corn leaf and its area, and that the backscattering coefficient of the surface was a linear function of its volumetric soil moisture content, it is found that the explicit inclusion of the effects of corn leaf size in the model led to an excellent fit between the observed and predicted backscattering coefficients. Also, an excellent power law relationship existed between the backscattering cross section of a corn leaf and its area.

  13. Key Proliferative Activity in the Junction between the Leaf Blade and Leaf Petiole of Arabidopsis1[W][OA

    PubMed Central

    Ichihashi, Yasunori; Kawade, Kensuke; Usami, Takeshi; Horiguchi, Gorou; Takahashi, Taku; Tsukaya, Hirokazu

    2011-01-01

    Leaves are the most important, fundamental units of organogenesis in plants. Although the basic form of a leaf is clearly divided into the leaf blade and leaf petiole, no study has yet revealed how these are differentiated from a leaf primordium. We analyzed the spatiotemporal pattern of mitotic activity in leaf primordia of Arabidopsis (Arabidopsis thaliana) in detail using molecular markers in combination with clonal analysis. We found that the proliferative zone is established after a short interval following the occurrence of a rod-shaped early leaf primordium; it is separated spatially from the shoot apical meristem and seen at the junction region between the leaf blade and leaf petiole and produces both leaf-blade and leaf-petiole cells. This proliferative region in leaf primordia is marked by activity of the ANGUSTIFOLIA3 (AN3) promoter as a whole and seems to be differentiated into several spatial compartments: activities of the CYCLIN D4;2 promoter and SPATULA enhancer mark parts of it specifically. Detailed analyses of the an3 and blade-on-petiole mutations further support the idea that organogenesis of the leaf blade and leaf petiole is critically dependent on the correct spatial regulation of the proliferative region of leaf primordia. Thus, the proliferative zone of leaf primordia is spatially differentiated and supplies both the leaf-blade and leaf-petiole cells. PMID:21880932

  14. Evaluation of Methane from Sisal Leaf Residue and Palash Leaf Litter

    NASA Astrophysics Data System (ADS)

    Arisutha, S.; Baredar, P.; Deshpande, D. M.; Suresh, S.

    2014-12-01

    The aim of this study is to evaluate methane production from sisal leaf residue and palash leaf litter mixed with different bulky materials such as vegetable market waste, hostel kitchen waste and digested biogas slurry in a laboratory scale anaerobic reactor. The mixture was prepared with 1:1 proportion. Maximum methane content of 320 ml/day was observed in the case of sisal leaf residue mixed with vegetable market waste as the feed. Methane content was minimum (47 ml/day), when palash leaf litter was used as feed. This was due to the increased content of lignin and polyphenol in the feedstock which were of complex structure and did not get degraded directly by microorganisms. Sisal leaf residue mixtures also showed highest content of volatile fatty acids (VFAs) as compared to palash leaf litter mixtures. It was observed that VFA concentration in the digester first increased, reached maximum (when pH was minimum) and then decreased.

  15. Patterns of effective permeability of leaf cuticles to acids

    SciTech Connect

    Hauser, H.D.; Walters, K.D.; Berg, V.S. )

    1993-01-01

    Plants in the field are frequently exposed to anthropogenic acid precipitation with pH values of 4 and below. For the acid to directly affect leaf tissues, it must pass through the leaf cuticle, but little is known about the permeability of cuticles to protons, of about the effect of different anions on this permeability. We investigated the movement of protons through isolated astomatous leaf cuticles of grapefruit (Citrus x paradisi Macfady.), rough lemon (Citrus limon [L.] Burm. fils cv Ponderosa), and pear (Pyrus communis L.) using hydrochloric, sulfuric, and nitric acids. Cuticles were enzymically isolated from leaves and placed in a diffusion apparatus with pH 4 acid on the morphological outer surface of the cuticle and degassed distilled water on the inner surface. Changes in pH of the solution on the inner surface were used to determine rates of effective permeability of the cuticles to the protons of these acids. Most cuticles exhibited an initial low permeability, lasting hours to days, then after a short transition displayed a significant higher permeability, which persisted until equilibrium was approached. The change in effective permeability appears to be reversible. Effective permeabilities were higher for sulfuric acid than for the others. A model of the movement of protons through the cuticle is presented, proposing that dissociated acid groups in channels within the cutin are first protonated by the acid, accounting for the low initial effective permeability; then protons pass freely through the channels, resulting in a higher effective permeability. 26 refs., 6 figs., 2 tabs.

  16. Wheat leaf photosynthesis loss due to leaf rust, with respect to lesion development and leaf nitrogen status.

    PubMed

    Robert, Corinne; Bancal, Marie-Odile; Ney, Bertrand; Lannou, Christian

    2005-01-01

    In wheat (Triticum aestivum cv. Soissons) plants grown under three different fertilisation treatments, we quantified the effect of leaf rust (Puccinia triticina) on flag leaf photosynthesis during the whole sporulation period. Bastiaans' model: Y = (1 - x)beta was used to characterize the relationship between relative leaf photosynthesis (Y) and disease severity (x). The evolution of the different types of symptoms induced by the pathogen (sporulating, chlorotic and necrosed tissues) was evaluated using image analysis. The beta-values varied from 2 to 11, 1.4-2, and 0.8-1 during the sporulation period, when considering the proportion of sporulating, sporulating + necrotic, and total diseased area, respectively. Leaf nitrogen (N) content did not change the effect of the disease on host photosynthesis. We concluded that leaf rust has no global effect on the photosynthesis of the symptomless parts of the leaves and that the large range in the quantification of leaf rust effect on the host, which is found in the literature, can be accounted for by considering the different symptom types. We discuss how our results could improve disease assessments and damage prediction in a wheat crop. PMID:15720636

  17. Nanofibers-based nanoweb promise superhydrophobic polyaniline: from star-shaped to leaf-shaped structures.

    PubMed

    Fan, Haosen; Wang, Hao; Guo, Jing; Zhao, Ning; Xu, Jian

    2013-11-01

    Star-shaped and leaf-shaped polyaniline (PANI) hierarchical structures with interlaced nanofibers on the surface were successfully prepared by chemical polymerization of aniline in the presence of lithium triflate (LT). Chemical structure and composition of the star-like PANI obtained were characterized by FTIR and UV-vis spectra. PANI 2D architectures can be tailored from star-shaped to leaf-shaped structures by change the concentration of LT. The synthesized star-like and leaf-like polyaniline show good superhydrophobicity with water contact angles of both above 150° due to the combination of the rough nanoweb structure and the low surface tension of fluorinated chain of dopant. This method is a facile and applicable strategy for a large-scale fabrication of 2D PANI micro/nanostructures. Many potential applications such as self-cleaning and antifouling coating can be expected based on the superhydrophobic PANI micro/nanostructures. PMID:23978289

  18. An economical non-destructive method for estimating eelgrass, Zostera marina (Potamogetonaceae) leaf growth rates: formal development and use in northwestern Baja California.

    PubMed

    Solana-Arellano, Elena; Echavarria-Heras, Héctor; Franco-Vizcaíno, Ernesto

    2008-09-01

    Seagrass beds provide much of the primary production in estuaries; host many fishes and fish larvae, and abate erosion. The present study presents original analytical methods for estimating mean leaf-growth rates of eelgrass (Zostera marina). The method was calibrated by using data collected in a Z. marina meadow at Punta Banda estuary in Baja California, Mexico. The analytical assessments were based on measurements of leaf length and standard regression procedures. We present a detailed explanation of the formal procedures involved in the derivation of these analytical methods. The measured daily leaf-growth rate was 10.9 mm d(-1) leaf(-1). The corresponding value projected by our method was 10.2 mm d(-1) leaf(-). The associated standard errors were of 0.53 and 0.56 mm d(-1) leaf(-1) respectively. The method was validated by projecting leaf-growth rates from an independent data set, which gave consistent results. The use of the method to obtain the mean leaf growth rate of a transplanted plot is also illustrated. Comparison of our leaf-growth data with previously reported assessments show the significant forcing of sea-surface temperature on eelgrass leaf dynamics. The formal constructs provided here are of general scope and can be applied to equivalent eelgrass data sets in a straightforward manner. PMID:19419023

  19. Simulating Leaf Area of Corn Plants at Contrasting Water Status

    Technology Transfer Automated Retrieval System (TEKTRAN)

    An exponential decay function was fitted with literature data to describe the decrease in leaf expansion rate as leaf water potential decreases. The fitted function was then applied to modify an existing leaf area simulation module in a soil-plant-atmosphere continuum model in order to simulate leaf...

  20. 7 CFR 29.3647 - Heavy Leaf (B Group).

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ..., close leaf structure, rough, lean in oil, dull finish, pale color intensity, inelastic, narrow, 70..., medium body, close leaf structure, rough, lean in oil, dull finish, pale color intensity, inelastic... Leaf. Mature, heavy, close leaf structure, rough, lean in oil, dull finish, pale color...

  1. 7 CFR 29.1163 - Smoking Leaf (H Group).

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards... may be waste. H5F—Low Quality Orange Smoking Leaf Mellow, open leaf structure, medium body, lean in... over 10 percent may be waste. H6F—Poor Quality Orange Smoking Leaf Mellow, open leaf structure,...

  2. 7 CFR 29.1163 - Smoking Leaf (H Group).

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards... may be waste. H5F—Low Quality Orange Smoking Leaf Mellow, open leaf structure, medium body, lean in... over 10 percent may be waste. H6F—Poor Quality Orange Smoking Leaf Mellow, open leaf structure,...

  3. 7 CFR 30.31 - Classification of leaf tobacco.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 2 2012-01-01 2012-01-01 false Classification of leaf tobacco. 30.31 Section 30.31... REGULATIONS TOBACCO STOCKS AND STANDARDS Classification of Leaf Tobacco Covering Classes, Types and Groups of Grades § 30.31 Classification of leaf tobacco. For the purpose of this classification leaf tobacco...

  4. 7 CFR 30.31 - Classification of leaf tobacco.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 2 2013-01-01 2013-01-01 false Classification of leaf tobacco. 30.31 Section 30.31... REGULATIONS TOBACCO STOCKS AND STANDARDS Classification of Leaf Tobacco Covering Classes, Types and Groups of Grades § 30.31 Classification of leaf tobacco. For the purpose of this classification leaf tobacco...

  5. 7 CFR 30.31 - Classification of leaf tobacco.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Classification of leaf tobacco. 30.31 Section 30.31... REGULATIONS TOBACCO STOCKS AND STANDARDS Classification of Leaf Tobacco Covering Classes, Types and Groups of Grades § 30.31 Classification of leaf tobacco. For the purpose of this classification leaf tobacco...

  6. 7 CFR 30.31 - Classification of leaf tobacco.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 2 2014-01-01 2014-01-01 false Classification of leaf tobacco. 30.31 Section 30.31... REGULATIONS TOBACCO STOCKS AND STANDARDS Classification of Leaf Tobacco Covering Classes, Types and Groups of Grades § 30.31 Classification of leaf tobacco. For the purpose of this classification leaf tobacco...

  7. 7 CFR 30.31 - Classification of leaf tobacco.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 2 2011-01-01 2011-01-01 false Classification of leaf tobacco. 30.31 Section 30.31... REGULATIONS TOBACCO STOCKS AND STANDARDS Classification of Leaf Tobacco Covering Classes, Types and Groups of Grades § 30.31 Classification of leaf tobacco. For the purpose of this classification leaf tobacco...

  8. 7 CFR 28.517 - Leaf Grade No. 7.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf Grade No. 7. 28.517 Section 28.517 Agriculture..., TESTING, AND STANDARDS Standards Official Cotton Standards of the United States for the Leaf Grade of American Pima Cotton § 28.517 Leaf Grade No. 7. American Pima cotton which in leaf is inferior to...

  9. 7 CFR 28.514 - Leaf Grade No. 4.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf Grade No. 4. 28.514 Section 28.514 Agriculture..., TESTING, AND STANDARDS Standards Official Cotton Standards of the United States for the Leaf Grade of American Pima Cotton § 28.514 Leaf Grade No. 4. Leaf grade No. 4 shall be American Pima cotton which...

  10. 7 CFR 28.513 - Leaf Grade No. 3.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf Grade No. 3. 28.513 Section 28.513 Agriculture..., TESTING, AND STANDARDS Standards Official Cotton Standards of the United States for the Leaf Grade of American Pima Cotton § 28.513 Leaf Grade No. 3. Leaf grade No. 3 shall be American Pima cotton which...

  11. 7 CFR 28.511 - Leaf Grade No. 1.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf Grade No. 1. 28.511 Section 28.511 Agriculture..., TESTING, AND STANDARDS Standards Official Cotton Standards of the United States for the Leaf Grade of American Pima Cotton § 28.511 Leaf Grade No. 1. Leaf grade No. 1 shall be American Pima cotton which...

  12. 7 CFR 28.516 - Leaf Grade No. 6.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf Grade No. 6. 28.516 Section 28.516 Agriculture..., TESTING, AND STANDARDS Standards Official Cotton Standards of the United States for the Leaf Grade of American Pima Cotton § 28.516 Leaf Grade No. 6. Leaf grade No. 6 shall be American Pima cotton which...

  13. 7 CFR 28.512 - Leaf Grade No. 2.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf Grade No. 2. 28.512 Section 28.512 Agriculture..., TESTING, AND STANDARDS Standards Official Cotton Standards of the United States for the Leaf Grade of American Pima Cotton § 28.512 Leaf Grade No. 2. Leaf grade No. 2 shall be American Pima cotton which...

  14. 7 CFR 28.515 - Leaf Grade No. 5.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf Grade No. 5. 28.515 Section 28.515 Agriculture..., TESTING, AND STANDARDS Standards Official Cotton Standards of the United States for the Leaf Grade of American Pima Cotton § 28.515 Leaf Grade No. 5. Leaf grade No. 5 shall be American Pima cotton which...

  15. What Is a Leaf? An Online Tutorial and Tests

    ERIC Educational Resources Information Center

    Burrows, Geoffrey

    2008-01-01

    A leaf is a fundamental unit in botany and understanding what constitutes a leaf is fundamental to many plant science activities. My observations and subsequent testing indicated that many students could not confidently and consistently recognise a leaf from a leaflet, or recognise basic leaf arrangements and the various types of compound or…

  16. The red edge of plant leaf reflectance

    NASA Technical Reports Server (NTRS)

    Horler, D. N. H.; Dockray, M.; Barber, J.

    1983-01-01

    A detailed study of the red edge spectral feature of green vegetation based on laboratory reflectance spectrophotometry is presented. A parameter lambda is defined as the wavelength is defined as the wavelength of maximum slope and found to be dependent on chlorophyll concentration. Species, development stage, leaf layering, and leaf water content of vegetation also influences lambda. The maximum slope parameter is found to be independent of simulated ground area coverage. The results are interpreted in terms of Beer's Law and Kubelka-Munk theory. The chlorophyll concentration dependence of lambda seems to be explained in terms of a pure absorption effect, and it is suggested that the existence of two lambda components arises from leaf scattering properties. The results indicate that red edge measurements will be valuable for assessment of vegetative chlorophyll status and leaf area index independently of ground cover variations, and will be particularly suitable for early stress detection.

  17. Reflectance model of a plant leaf

    NASA Technical Reports Server (NTRS)

    Kumar, R.; Silva, L.

    1973-01-01

    A light ray, incident at 5 deg to the normal, is geometrically plotted through the drawing of the cross section of a soybean leaf using Fresnel's Equations and Snell's Law. The optical mediums of the leaf considered for ray tracing are: air, cell sap, chloroplast, and cell wall. The above ray is also drawn through the same leaf cross section considering cell wall and air as the only optical mediums. The values of the reflection and transmission found from ray tracing agree closely with the experimental results obtained using a Beckman DK-2A Spectroreflectometer. Similarly a light ray, incident at about 60 deg to the normal, is drawn through the palisade cells of a soybean leaf to illustrate the pathway of light, incident at an oblique angle, through the palisade cells.

  18. Monitoring Air Quality with Leaf Yeasts.

    ERIC Educational Resources Information Center

    Richardson, D. H. S.; And Others

    1985-01-01

    Proposes that leaf yeast serve as quick, inexpensive, and effective techniques for monitoring air quality. Outlines procedures and provides suggestions for data analysis. Includes results from sample school groups who employed this technique. (ML)

  19. Photosynthesis and Respiration in Leaf Slices.

    ERIC Educational Resources Information Center

    Brown, Simon

    1998-01-01

    Demonstrates how leaf slices provide an inexpensive material for illustrating several fundamental points about the biochemistry of photosynthesis and respiration. Presents experiments that illustrate the effects of photon flux density and herbicides and carbon dioxide concentration. (DDR)

  20. Remote sensing of leaf water status

    NASA Technical Reports Server (NTRS)

    Ripple, William J.; Schrumpf, Barry J.

    1987-01-01

    Relative water content (RWC) measurements were made concurrently with spectral reflectance measurements from individual snapbean leaves. The relationships between spectra and RWC were described using second order polynomial equations. The middle infrared bands most sensitive to changes in leaf RWC also had the highest water absorption coefficients, as published by Curcio Petty (1951). The relationship between reflectance at 2100nm and total water potential for a single leaf was found to be linear.

  1. Leaf structural traits of tropical woody species resistant to cement dust.

    PubMed

    Siqueira-Silva, Advanio Inácio; Pereira, Eduardo Gusmão; Modolo, Luzia Valentina; Paiva, Elder Antonio Sousa

    2016-08-01

    Cement industries located nearby limestone outcrops in Brazil have contributed to the coating of cement dust over native plant species. However, little is known about the extent of the response of tropical woody plants to such environmental pollutant particularly during the first stages of plant development and establishment. This work focused on the investigation of possible alterations in leaf structural and ultrastructural traits of 5-month-old Guazuma ulmifolia Lam. (Malvaceae), 6-month-old Myracrodruon urundeuva Allemão (Anacardiaceae), and 9-month-old Trichilia hirta L. (Meliaceae) challenged superficially with cement dust during new leaf development. Leaf surface of plants, the soil or both (leaf plus soil), were treated (or not) for 60 days, under controlled conditions, with cement dust at 2.5 or 5.0 mg cm(-2). After exposure, no significant structural changes were observed in plant leaves. Also, no plant death was recorded by the end of the experiment. There was also some evidence of localized leaf necrosis in G. ulmifolia and T. hirta, leaf curling in M. urundeuva and T. hirta, and bulges formation on epidermal surface of T. hirta, after cement dust contact with plant shoots. All species studied exhibited stomata obliteration while T. hirta, in particular, presented early leaf abscission, changes in cellular relief, and organization and content of midrib cells. No significant ultrastructural alterations were detected under the experimental conditions studied. Indeed, mesophyll cells presented plastids with intact membrane systems. The high plant survival rates, together with mild morphoanatomic traits alterations in leaves, indicate that G. ulmifolia is more resistant to cement dust pollutant, followed by M. urundeuva and T. hirta. Thus, the three plant species are promising for being used to revegetate areas impacted by cement industries activities. PMID:27146683

  2. Cleanup of trimethylamine (fishy odor) from contaminated air by various species of Sansevieria spp. and their leaf materials.

    PubMed

    Boraphech, Phattara; Suksabye, Parinda; Kulinfra, Nipaporn; Kongsang, Wascharangkoon; Thiravetyan, Paitip

    2016-10-01

    Removal of trimethylamine (TMA) by 10 different living Sansevieria spp. and their dried leaf materials was studied. The results showed that living Sansevieria kirkii was the most effective plant while Sansevieria masoniana was the least effective in TMA removal. Two major pathways were involved in stomata opening and epicuticular wax on the leaf surface. In the presence of TMA, the stomata opening in Sansevieria spp. was induced, which enhanced TMA removal under light conditions. Dried leaf powders of Sansevieria spp. adsorbed TMA through their waxes. Therefore, both living and non-living Sansevieria spp. can be effectively used for removal of TMA. PMID:27294282

  3. Leaf morphology shift linked to climate change

    PubMed Central

    Guerin, Greg R.; Wen, Haixia; Lowe, Andrew J.

    2012-01-01

    Climate change is driving adaptive shifts within species, but research on plants has been focused on phenology. Leaf morphology has demonstrated links with climate and varies within species along climate gradients. We predicted that, given within-species variation along a climate gradient, a morphological shift should have occurred over time due to climate change. We tested this prediction, taking advantage of latitudinal and altitudinal variations within the Adelaide Geosyncline region, South Australia, historical herbarium specimens (n = 255) and field sampling (n = 274). Leaf width in the study taxon, Dodonaea viscosa subsp. angustissima, was negatively correlated with latitude regionally, and leaf area was negatively correlated with altitude locally. Analysis of herbarium specimens revealed a 2 mm decrease in leaf width (total range 1–9 mm) over 127 years across the region. The results are consistent with a morphological response to contemporary climate change. We conclude that leaf width is linked to maximum temperature regionally (latitude gradient) and leaf area to minimum temperature locally (altitude gradient). These data indicate a morphological shift consistent with a direct response to climate change and could inform provenance selection for restoration with further investigation of the genetic basis and adaptive significance of observed variation. PMID:22764114

  4. Association of tomato leaf curl Sudan virus with leaf curl disease of tomato in Jeddah, Saudi Arabia.

    PubMed

    Sohrab, Sayed Sartaj; Yasir, Muhammad; El-Kafrawy, Sherif Ali; Abbas, Ayman T; Mousa, Magdi Ali Ahmed; Bakhashwain, Ahmed A

    2016-06-01

    Tomato is an important vegetable crop and its production is adversely affected by leaf curl disease caused by begomovirus. Leaf curl disease is a serious concern for tomato crops caused by begomovirus in Jeddah, Kingdom of Saudi Arabia. Tomato leaf curl disease has been shown to be mainly caused either by tomato leaf curl Sudan virus or tomato yellow leaf curl virus as well as tomato leaf curl Oman virus. Many tomato plants infected with monopartite begomoviruses were also found to harbor a symptom enhancing betasatellites. Here we report the association of tomato leaf curl Sudan virus causing leaf curl disease of tomato in Jeddah, Kingdom of Saudi Arabia. The complete genome sequence analysis showed highest (99.9 %) identity with tomato leaf curl Sudan virus causing leaf curl disease in Arabian Peninsula. In phylogenetic relationships analysis, the identified virus formed closest cluster with tomato leaf curl Sudan virus. In recombination analysis study, the major parent was identified as tomato leaf curl Sudan virus. Findings of this study strongly supports the associated virus is a variant of tomato leaf curl Sudan virus causing disease in Sudan, Yemen and Arabian Peninsula. The betasatellites sequence analysis showed highest identity (99.8 %) with tomato leaf curl betasatellites-Amaranthus-Jeddah. The phylogenetic analysis result based on betasatellites formed closed cluster with tomato yellow leaf curl Oman betasatellites. The importance of these findings and occurrence of begomovirus in new geographic regions causing leaf curl disease of tomato in Jeddah, Kingdom of Saudi Arabia are discussed. PMID:27366765

  5. Designing bioinspired superoleophobic surfaces

    NASA Astrophysics Data System (ADS)

    Brown, Philip S.; Bhushan, Bharat

    2016-01-01

    Nature provides a range of functional surfaces, for example, water-repellent or superhydrophobic surfaces, most common among them the lotus leaf. While water-repellency is widespread in nature, oil-repellency is typically limited to surfaces submerged in water, such as fish scales. To achieve oleophobicity in air, inspiration must be taken from natural structures and chemistries that are not readily available in nature need to be introduced. Researchers usually turn to fluorinated materials to provide the low surface energy that, when combined with bioinspired surface topography, is the key to unlocking oil-repellency. This review presents the state-of-the-art in the fabrication of superoleophobic surfaces.

  6. Dry acid deposition on leaves of Ligustrum and a new surrogate leaf

    SciTech Connect

    Ondo, J.L.; John, W.; Wall, S.M.

    1984-01-01

    The dry deposition of acidic particles and gases on plants depends on micrometeorology in the canopy and on the surface structure of the leaves. The authors chose two methods to collect and analyze this deposition: washing sulfate and nitrate deposits from the leaves of two species of Ligustrum, an ornamental shrub, and using a surrogate leaf which would absorb acidic gases through pores into a reservoir. The plants are kept in 5-gallon pots in order to be transportable. The leaves are washed, then exposed for a given length of time. Then the leaves are harvested and extracted in distilled water. This extract is analyzed by ion chromatography for sulfate and nitrate. The surrogate leaf is constructed with a nuclepore filter membrane simulating the stomatal openings of a leaf. There is a moist filter in the interior leading to a reservoir. Sulfur dioxide and other acidic gases diffuse through the nuclepore pores and are absorbed in the moist filter. After exposure the exterior surfaces are washed to extract any dry particulate, and the interior filter is analyzed for dissolved acidic gases. The ''leaf'' is small enough to be placed in the canopy in field studies. This surrogate leaf has also been used as a passive monitor in indoor air pollution studies. The surrogate leaves and the ligustrum have been exposed side by side at sites in Berkeley and in the Los Angeles air basin. A comparison has been made between the deposition on natural leaves and the deposition on the artificial leaves.

  7. Combined effects of girdling and leaf removal on fluorescence characteristic of Alhagi sparsifolia leaf senescence.

    PubMed

    Tang, G; Li, X; Lin, L; Guo, H; Li, L

    2015-09-01

    Plant senescence is largely influenced by carbohydrate content. In order to investigate the impact of carbohydrate content on leaf senescence and photosystem II (PSII) during the senescence process, phloem girdling (PG), leaf removal (LR) and a combination of phloem girdling and leaf removal (GR) were performed on Alhagi sparsifolia (Fabaceae) at the end of the growing season. The results showed that during senescence, leaf soluble sugar content, starch content, the energy absorbed by the unit reaction centre (ABS/RC) increased; whereas, leaf photosynthetic rate, photosynthetic pigment content, maximum photochemical efficiency (φPo ) and energy used by the acceptor site in electron transfer (ETo/RC) decreased. The degree of change was PG > GR > CK (control) > LR. The results of the present work implied that phloem girdling (PG) significantly accelerated leaf senescence, and that single leaf removal (LR) slightly delayed leaf senescence; although leaf removal significantly delayed the senescence process on the girdled leaf (GR). Natural or delayed senescence only slightly inhibited the acceptor site of PSII and did not damage the donor site of PSII. On the other hand, induced senescence not only damaged the donor site of PSII (e.g. oxygen-evolving complex), but also significantly inhibited the acceptor site of PSII. In addition, leaf senescence led to an increase in the energy absorbed by the unit reaction centre (ABS/RC), which subsequently resulted in increasing excitation pressure in the reaction centre (DIo/RC), as well as additional saved Car for absorbing residual light energy and quenching reactive oxygen species during senescence. PMID:25662611

  8. Effects of crown development on leaf irradiance, leaf morphology and photosynthetic capacity in a peach tree.

    PubMed

    Walcroft, Adrian; Le Roux, Xavier; Diaz-Espejo, Antonio; Dones, Nicolas; Sinoquet, Hervé

    2002-09-01

    The three-dimensional (3-D) architecture of a peach tree (Prunus persica L. Batsch) growing in an orchard near Avignon, France, was digitized in April 1999 and again four weeks later in May 1999 to quantify increases in leaf area and crown volume as shoots developed. A 3-D model of radiation transfer was used to determine effects of changes in leaf area density and canopy volume on the spatial distribution of absorbed quantum irradiance (PAR(a)). Effects of changes in PAR(a) on leaf morphological and physiological properties were determined. Leaf mass per unit area (M(a)) and leaf nitrogen concentration per unit leaf area (N(a)) were both nonlinearly related to PAR(a), and there was a weak linear relationship between leaf nitrogen concentration per unit leaf mass (N(m)) and PAR(a). Photosynthetic capacity, defined as maximal rates of ribulose-1,5-bisphosphate carboxylase (Rubisco) carboxylation (V(cmax)) and electron transport (J(max)), was measured on leaf samples representing sunlit and shaded micro-environments at the same time that the tree crown was digitized. Both V(cmax) and J(max) were linearly related to N(a) during May, but not in April when the range of N(a) was low. Photosynthetic capacity per unit N(a) appeared to decline between April and May. Variability in leaf nitrogen partitioning between Rubisco carboxylation and electron transport was small, and the partitioning coefficients were unrelated to N(a). Spatial variability in photosynthetic capacity resulted from acclimation to varying PAR(a) as the crown developed, and acclimation was driven principally by changes in M(a) rather than the amount or partitioning of leaf nitrogen. PMID:12204849

  9. Molecular characterization of Chilli leaf curl virus and satellite molecules associated with leaf curl disease of Amaranthus spp.

    PubMed

    George, B; Kumar, R Vinoth; Chakraborty, S

    2014-04-01

    Amaranthus, collectively known as amaranth, is an annual or short-lived perennial plant used as leafy vegetables, cereals and for ornamental purposes in many countries including India. During 2011, leaf samples of Amaranthus plants displaying leaf curling, leaf distortion, leaf crinkling and yellow leaf margins were collected from Banswara district, Rajasthan in India. Full-length clones of a monopartite begomovirus, a betasatellite and an alphasatellite were characterized. The complete nucleotide sequence of the isolated begomovirus features as a typical 'Old World' begomovirus with the highest nucleotide per cent identity with Chilli leaf curl virus and hence, considered as an isolate of Chilli leaf curl virus. The complete nucleotide sequences of betasatellite and alphasatellite possess maximum nucleotide identity with Tomato yellow leaf curl Thailand betasatellite and Chilli leaf curl alphasatellite, respectively. This is the first report of the association of chilli-infecting begomovirus and satellite molecules infecting a new host, Amaranthus, causing leaf curl disease. PMID:24368759

  10. Direct leaf wetness measurements and its numerical analysis using a multi-layer atmosphere-soil-vegetation model at a grassland site in pre-alpine region in Germany

    NASA Astrophysics Data System (ADS)

    Katata, Genki; Held, Andreas; Mauder, Matthias

    2014-05-01

    The wetness of plant leaf surfaces (leaf wetness) is important in meteorological, agricultural, and environmental studies including plant disease management and the deposition process of atmospheric trace gases and particles. Although many models have been developed to predict leaf wetness, wetness data directly measured at the leaf surface for model validations are still limited. In the present study, the leaf wetness was monitored using seven electrical sensors directly clipped to living leaf surfaces of thin and broad-leaved grasses. The measurements were carried out at the pre-alpine grassland site in TERestrial ENvironmental Observatories (TERENO) networks in Germany from September 20 to November 8, 2013. Numerical simulations of a multi-layer atmosphere-SOiL-VEGetation model (SOLVEG) developed by the authors were carried out for analyzing the data. For numerical simulations, the additional routine meteorological data of wind speed, air temperature and humidity, radiation, rainfall, long-wave radiative surface temperature, surface fluxes, ceilometer backscatter, and canopy or snow depth were used. The model reproduced well the observed leaf wetness, net radiation, momentum and heat, water vapor, and CO2 fluxes, surface temperature, and soil temperature and moisture. In rain-free days, a typical diurnal cycle as a decrease and increase during the day- and night-time, respectively, was observed in leaf wetness data. The high wetness level was always monitored under rain, fog, and snowcover conditions. Leaf wetness was also often high in the early morning due to thawing of leaf surface water frozen during a cold night. In general, leaf wetness was well correlated with relative humidity (RH) in condensation process, while it rather depended on wind speed in evaporation process. The comparisons in RH-wetness relations between leaf characteristics showed that broad-leaved grasses tended to be wetter than thin grasses.

  11. Simplified expressions for radiation scattering through canopies with ellipsoidal leaf angle distributions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The ability to simulate the surface energy balance and microclimate within a plant canopy is contingent upon accurate simulation of radiation exchange within the canopy. Accurate radiation simulations require some assumption of leaf angle distribution to compute transmissivity, reflection and scatte...

  12. Estimating leaf area index from Landsat using MODIS LAI products and field measurements as reference

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Leaf area index (LAI) is a key biophysical parameter used in most land surface models. Operationally, LAI products currently used typically come from coarse resolution sensors such as the Moderate Resolution Imaging Spectroradiometer (MODIS). While coarse resolution data at the kilometer scale are o...

  13. Retrieving leaf area index from remotely sensed data using advanced statistical approaches

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Mapping and monitoring leaf area index (LAI) is important for spatially distributed modeling of surface energy balance, evapotranspiration and vegetation productivity. Remote sensing can facilitate the rapid collection of LAI information on individual fields over large areas, in a time and cost-effe...

  14. A simple method for retrieving leaf area index from landsat using MODIS LAI products as reference

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Leaf Area Index (LAI) is a key parameter in most land surface models. Models that operate at multiple spatial scales may require consistent LAI inputs at different spatial resolutions or from different sensors. For example, the Atmosphere-Land Exchange Inverse (ALEXI) model and associated disaggrega...

  15. On the relationship between nominal light use efficiency and leaf chlorophyll

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Remotely sensed data allows for indirect estimates of key biophysical and biochemical parameters needed for accurate and reliable assessments of land-surface carbon, energy and water fluxes. Biophysical parameters such as Leaf Area Index (LAI), which provides information useful for determining vari...

  16. Does leaf manipulation affect leaf appearance in italian ryegrass (Lolium multiflorum Lam.)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Mechanical stimuli such as rubbing, shaking, or flexing plants can alter their growth rates and morphologies. Plant response to mechanical stress can result in delayed plant growth, reduced leaf size, shorten and thicken stems, and reduced yields. Repeated measurements, such as leaf counting or me...

  17. Coming of leaf age: control of growth by hydraulics and metabolics during leaf ontogeny.

    PubMed

    Pantin, Florent; Simonneau, Thierry; Muller, Bertrand

    2012-10-01

    Leaf growth is the central process facilitating energy capture and plant performance. This is also one of the most sensitive processes to a wide range of abiotic stresses. Because hydraulics and metabolics are two major determinants of expansive growth (volumetric increase) and structural growth (dry matter increase), we review the interaction nodes between water and carbon. We detail the crosstalks between water and carbon transports, including the dual role of stomata and aquaporins in regulating water and carbon fluxes, the coupling between phloem and xylem, the interactions between leaf water relations and photosynthetic capacity, the links between Lockhart's hydromechanical model and carbon metabolism, and the central regulatory role of abscisic acid. Then, we argue that during leaf ontogeny, these interactions change dramatically because of uncoupled modifications between several anatomical and physiological features of the leaf. We conclude that the control of leaf growth switches from a metabolic to a hydromechanical limitation during the course of leaf ontogeny. Finally, we illustrate how taking leaf ontogeny into account provides insights into the mechanisms underlying leaf growth responses to abiotic stresses that affect water and carbon relations, such as elevated CO2, low light, high temperature and drought. PMID:22924516

  18. Estimating global specific leaf area from MODIS leaf area index and model-simulated foliage mass

    NASA Astrophysics Data System (ADS)

    Baruah, P. J.; Yasuoka, Y.; Ito, A.; Dye, D.

    2006-12-01

    Specific leaf area (SLA) is an important leaf trait that is universally correlated positively to leaf nitrogen, leaf turnover rates, relative growth rate and most importantly, photosynthetic capacity. Though SLA is genetically encoded, it is often spatially variable within a species and within a single biome due to variable environmental conditions. However, without a global SLA map, global ecosystem models that use SLA, generally fix a single value for a particular biome. In this study, we develop a methodology to estimate global SLA from a remote sensing-derived key ecosystem variable, leaf area index and foliage mass estimated by a terrestrial ecosystem model SimCYCLE. SimCYCLE uses climatic inputs, land-cover data and biomass-allocation to estimate leaf biomass in a process-based scheme. Model-estimated foliage mass and MODIS leaf area index are assumed to represent the most-accurate ground condition to estimate SLA for the entire globe at 0.5 degree resolution. Validation of estimated specific leaf area is done with a published field-sampled global dataset, and additional field-sampled SLA data collected from published literatures. The validation data is also used for rectification of unrealistic values of estimated SLA to produce a global SLA map, which we strongly believe, would be valuable to improve estimates of carbon dynamic across individual biomes upon assimilation with the ecosystem models.

  19. Leaf endophyte load and fungal garden development in leaf-cutting ants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Previous work has shown that leaf-cutting ants prefer to cut leaf material that is relatively low in fungal endophyte content. Such a preference suggests that fungal endophytes exact a cost on the ants or on the development of their colonies. We hypothesized that endophytes may play a role in thei...

  20. Reaction of sorghum lines to zonate leaf spot and rough leaf spot

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Abundant, frequent rains, along with humid and cloudy conditions during the early part of the 2015 growing season, provided conducive conditions for an unusually severe outbreak of zonate leaf spot and rough leaf spot in a block of sorghum lines at the Texas A&M AgriLife Research Farm, Burleson Coun...

  1. Measurement of leaf relative water content by infrared reflectance

    NASA Technical Reports Server (NTRS)

    Hunt, E. Raymond, Jr.; Rock, Barrett N.; Nobel, Park S.

    1987-01-01

    From basic considerations and Beer's law, a leaf water content index incorporating reflectances of wavelengths from 0.76 to 0.90 microns and from 1.55 to 1.75 microns was developed that relates leaf reflectance to leaf relative water content. For the leaf succulent, Agave deserti, the leaf water content index was not significantly different from the relative water content for either individual leaves or an entire plant. Also, the relative water contents of intact plants of Encelia farinosa and Hilaria rigida in the field were estimated by the leaf water content index; variations in the proportion of living to dead leaf area could cause large errors in the estimate of relative water content. Thus, the leaf water content index may be able to estimate average relative water content of canopies when TM4 and TM5 are measured at a known relative water content and fraction of dead leaf material.

  2. How do leaf veins influence the worldwide leaf economic spectrum? Review and synthesis.

    PubMed

    Sack, Lawren; Scoffoni, Christine; John, Grace P; Poorter, Hendrik; Mason, Chase M; Mendez-Alonzo, Rodrigo; Donovan, Lisa A

    2013-10-01

    Leaf vein traits are implicated in the determination of gas exchange rates and plant performance. These traits are increasingly considered as causal factors affecting the 'leaf economic spectrum' (LES), which includes the light-saturated rate of photosynthesis, dark respiration, foliar nitrogen concentration, leaf dry mass per area (LMA) and leaf longevity. This article reviews the support for two contrasting hypotheses regarding a key vein trait, vein length per unit leaf area (VLA). Recently, Blonder et al. (2011, 2013) proposed that vein traits, including VLA, can be described as the 'origin' of the LES by structurally determining LMA and leaf thickness, and thereby vein traits would predict LES traits according to specific equations. Careful re-examination of leaf anatomy, published datasets, and a newly compiled global database for diverse species did not support the 'vein origin' hypothesis, and moreover showed that the apparent power of those equations to predict LES traits arose from circularity. This review provides a 'flux trait network' hypothesis for the effects of vein traits on the LES and on plant performance, based on a synthesis of the previous literature. According to this hypothesis, VLA, while virtually independent of LMA, strongly influences hydraulic conductance, and thus stomatal conductance and photosynthetic rate. We also review (i) the specific physiological roles of VLA; (ii) the role of leaf major veins in influencing LES traits; and (iii) the role of VLA in determining photosynthetic rate per leaf dry mass and plant relative growth rate. A clear understanding of leaf vein traits provides a new perspective on plant function independently of the LES and can enhance the ability to explain and predict whole plant performance under dynamic conditions, with applications towards breeding improved crop varieties. PMID:24123455

  3. The INDETERMINATE DOMAIN Protein BROAD LEAF1 Limits Barley Leaf Width by Restricting Lateral Proliferation.

    PubMed

    Jöst, Moritz; Hensel, Götz; Kappel, Christian; Druka, Arnis; Sicard, Adrien; Hohmann, Uwe; Beier, Sebastian; Himmelbach, Axel; Waugh, Robbie; Kumlehn, Jochen; Stein, Nils; Lenhard, Michael

    2016-04-01

    Variation in the size, shape, and positioning of leaves as the major photosynthetic organs strongly impacts crop yield, and optimizing these aspects is a central aim of cereal breeding [1, 2]. Leaf growth in grasses is driven by cell proliferation and cell expansion in a basal growth zone [3]. Although several factors influencing final leaf size and shape have been identified from rice and maize [4-14], what limits grass leaf growth in the longitudinal or transverse directions during leaf development remains poorly understood. To identify factors involved in this process, we characterized the barley mutant broad leaf1 (blf1). Mutants form wider but slightly shorter leaves due to changes in the numbers of longitudinal cell files and of cells along the leaf length. These differences arise during primordia outgrowth because of more cell divisions in the width direction increasing the number of cell files. Positional cloning, analysis of independent alleles, and transgenic complementation confirm that BLF1 encodes a presumed transcriptional regulator of the INDETERMINATE DOMAIN family. In contrast to loss-of-function mutants, moderate overexpression of BLF1 decreases leaf width below wild-type levels. A functional BLF1-vYFP fusion protein expressed from the endogenous promoter shows a dynamic expression pattern in the shoot apical meristem and young leaf primordia. Thus, we propose that the BLF1 gene regulates barley leaf size by restricting cell proliferation in the leaf-width direction. Given the agronomic importance of canopy traits in cereals, identifying functionally different BLF1 alleles promises to allow for the generation of optimized cereal ideotypes. PMID:26996502

  4. Computer vision cracks the leaf code.

    PubMed

    Wilf, Peter; Zhang, Shengping; Chikkerur, Sharat; Little, Stefan A; Wing, Scott L; Serre, Thomas

    2016-03-22

    Understanding the extremely variable, complex shape and venation characters of angiosperm leaves is one of the most challenging problems in botany. Machine learning offers opportunities to analyze large numbers of specimens, to discover novel leaf features of angiosperm clades that may have phylogenetic significance, and to use those characters to classify unknowns. Previous computer vision approaches have primarily focused on leaf identification at the species level. It remains an open question whether learning and classification are possible among major evolutionary groups such as families and orders, which usually contain hundreds to thousands of species each and exhibit many times the foliar variation of individual species. Here, we tested whether a computer vision algorithm could use a database of 7,597 leaf images from 2,001 genera to learn features of botanical families and orders, then classify novel images. The images are of cleared leaves, specimens that are chemically bleached, then stained to reveal venation. Machine learning was used to learn a codebook of visual elements representing leaf shape and venation patterns. The resulting automated system learned to classify images into families and orders with a success rate many times greater than chance. Of direct botanical interest, the responses of diagnostic features can be visualized on leaf images as heat maps, which are likely to prompt recognition and evolutionary interpretation of a wealth of novel morphological characters. With assistance from computer vision, leaves are poised to make numerous new contributions to systematic and paleobotanical studies. PMID:26951664

  5. BOREAS TE-9 NSA Leaf Chlorophyll Density

    NASA Technical Reports Server (NTRS)

    Hall, Forrest G. (Editor); Curd, Shelaine (Editor); Margolis, Hank; Sy, Mikailou

    2000-01-01

    The BOREAS TE-9 team collected several data sets related to chemical and photosynthetic properties of leaves in boreal forest tree species. These data were collected to help provide an explanation of potential seasonal and spatial changes of leaf pigment properties in boreal forest species at the NSA. At different dates (FFC-Winter, FFC-Thaw, IFC-1, IFC-2, and IMC-3), foliage samples were collected from the upper third of the canopy for five NSA sites (YJP, OJP, OBS, UBS, and OA) near Thompson, Manitoba. Subsamples of 100 needles for black spruce, 20 needles for jack pine, and single leaf for trembling aspen were cut into pieces and immersed in a 20-mL DMF aliquot in a Nalgene test tube. The extracted foliage materials were then oven-dried at 68 C for 48 hours and weighed. Extracted leaf dry weight was converted to a total leaf area basis to express the chlorophyll content in mg/sq cm of total leaf area. The data are provided in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC).

  6. Photosynthesis, Transpiration, Leaf Temperature, and Stomatal Activity of Cotton Plants under Varying Water Potentials

    PubMed Central

    Pallas, J. E.; Michel, B. E.; Harris, D. G.

    1967-01-01

    Cotton plants, Gossypium hirsutum L. were grown in a growth room under incident radiation levels of 65, 35, and 17 Langleys per hour to determine the effects of vapor pressure deficits (VPD's) of 2, 9, and 17 mm Hg at high soil water potential, and the effects of decreasing soil water potential and reirrigation on transpiration, leaf temperature, stomatal activity, photosynthesis, and respiration at a VPD of 9 mm Hg. Transpiration was positively correlated with radiation level, air VPD and soil water potential. Reirrigation following stress led to slow recovery, which may be related to root damage occurring during stress. Leaf water potential decreased with, but not as fast as, soil water potential. Leaf temperature was usually positively correlated with light intensity and negatively correlated with transpiration, air VPD, and soil water. At high soil water, leaf temperatures ranged from a fraction of 1 to a few degrees above ambient, except at medium and low light and a VPD of 19 mm Hg when they were slightly below ambient, probably because of increased transpirational cooling. During low soil water leaf temperatures as high as 3.4° above ambient were recorded. Reirrigation reduced leaf temperature before appreciably increasing transpiration. The upper leaf surface tended to be warmer than the lower at the beginning of the day and when soil water was adequate; otherwise there was little difference or the lower surface was warmer. This pattern seemed to reflect transpiration cooling and leaf position effects. Although stomata were more numerous in the lower than the upper epidermis, most of the time a greater percentage of the upper were open. With sufficient soil water present, stomata opened with light and closed with darkness. Fewer stomata opened under low than high light intensity and under even moderate, as compared with high soil water. It required several days following reirrigation for stomata to regain original activity levels. Apparent photosynthesis

  7. Factors affecting survival of bacteriophage on tomato leaf surfaces.

    PubMed

    Iriarte, F B; Balogh, B; Momol, M T; Smith, L M; Wilson, M; Jones, J B

    2007-03-01

    The ability of bacteriophage to persist in the phyllosphere for extended periods is limited by many factors, including sunlight irradiation, especially in the UV zone, temperature, desiccation, and exposure to copper bactericides. The effects of these factors on persistence of phage and formulated phage (phage mixed with skim milk) were evaluated. In field studies, copper caused significant phage reduction if applied on the day of phage application but not if applied 4 or 7 days in advance. Sunlight UV was evaluated for detrimental effects on phage survival on tomato foliage in the field. Phage was applied in the early morning, midmorning, early afternoon, and late evening, while UVA plus UVB irradiation and phage populations were monitored. The intensity of UV irradiation positively correlated with phage population decline. The protective formulation reduced the UV effect. In order to demonstrate direct effects of UV, phage suspensions were exposed to UV irradiation and assayed for effectiveness against bacterial spot of tomato. UV significantly reduced phage ability to control bacterial spot. Ambient temperature had a pronounced effect on nonformulated phage but not on formulated phages. The effects of desiccation and fluorescent light illumination on phage were investigated. Desiccation caused a significant but only slight reduction in phage populations after 60 days, whereas fluorescent light eliminated phages within 2 weeks. The protective formulation eliminated the reduction caused by both of these factors. Phage persistence was dramatically affected by UV, while the other factors had less pronounced effects. Formulated phage reduced deleterious effects of the studied environmental factors. PMID:17259361

  8. Factors Affecting Survival of Bacteriophage on Tomato Leaf Surfaces

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The ability of bacteriophage to persist in the phyllosphere for extended periods is limited by many factors, including sunlight irradiation, especially in the UV zone, temperature, desiccation, and exposure to copper bactericides. The effects of these factors on persistence of phage and formulated p...

  9. Stomatal Density Influences Leaf Water and Leaf Wax D/H Values in Arabidopsis

    NASA Astrophysics Data System (ADS)

    Lee, H.; Feakins, S. J.; Sternberg, L. O.

    2014-12-01

    The hydrogen isotopic composition (δD) of plant leaf wax is a powerful tool to study the hydrology of past and present environments. The δD value of leaf waxes is known to primarily reflect the δD value of source water, modified by biological fractionations commonly summarized as the 'net or apparent' fractionation. It remains a challenge, however, to quantitatively relate the isotopic composition of the end product (wax) back to that of the precursor (water) because multiple isotope effects contributing to the net fractionation are not yet well understood. Transgenic variants have heretofore unexplored potential to isolate individual isotope effects. Here we report the first hydrogen isotopic measurements from transgenic Arabidopsis thaliana plants with calculations of leaf water enrichment, net and biosynthetic fractionation values from measured δD of plant waters and leaf wax n-alkanes. We employed transgenic Arabidopsis leaves, engineered to have different stomatal density, by differential expression of the stomatal growth hormone stomagen. Comparison of variants and wild types allow us to isolate the effects of stomatal density on leaf water and the net fractionation expressed by leaf wax biomarkers. Results show that transgenic leaves with denser pores have more enriched leaf water and leaf wax δD values than wild type and even more so than transgenic leaves with sparse stomata (difference of 10 ‰). Our findings that stomatal density controls leaf water and leaf wax δD values adds insights into the cause of variations in net fractionations between species, as well as suggesting that geological variations in stomatal density may modulate the sedimentary leaf wax δD record. In nature, stomatal density varies between species and environments, and all other factors being equal, this will contribute to variations in fractionations observed. Over geological history, lower stomatal densities occur at times of elevated pCO2; our findings predict reduced leaf

  10. Leaf seal for inner and outer casings of a turbine

    DOEpatents

    Schroder, Mark Stewart; Leach, David

    2002-01-01

    A plurality of arcuate, circumferentially extending leaf seal segments form an annular seal spanning between annular sealing surfaces of inner and outer casings of a turbine. The ends of the adjoining seal segments have circumferential gaps to enable circumferential expansion and contraction of the segments. The end of a first segment includes a tab projecting into a recess of a second end of a second segment. Edges of the tab seal against the sealing surfaces of the inner and outer casings have a narrow clearance with opposed edges of the recess. An overlying cover plate spans the joint. Leakage flow is maintained at a minimum because of the reduced gap between the radially spaced edges of the tab and recess, while the seal segments retain the capacity to expand and contract circumferentially.

  11. Synthesis of monodispersed silver nanoparticles using Hibiscus cannabinus leaf extract and its antimicrobial activity

    NASA Astrophysics Data System (ADS)

    Bindhu, M. R.; Umadevi, M.

    2013-01-01

    Synthesis of silver nanoparticles using leaf extract of Hibiscus cannabinus has been investigated. The influences of different concentration of H. cannabinus leaf extract, different metal ion concentration and different reaction time on the above cases on the synthesis of nanoparticles were evaluated. The synthesized nanoparticles were characterized using UV-vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and Transmission Electron Microscopy (TEM). The prepared silver nanoparticles were monodispersed, spherical in shape with the average particle size of 9 nm and shows surface plasmon peak at 446 nm. The study also reveals that the ascorbic acid present in H. cannabinus leaf extract has been used as reducing agent. The prepared silver nanoparticle shows good antimicrobial activity against Escherichia coli, Proteus mirabilis and Shigella flexneri.

  12. Transport theory for a leaf canopy of finite-dimensional scattering centers

    NASA Technical Reports Server (NTRS)

    Myneni, Ranga B.; Marshak, Alexander L.; Kniazikhin, Iurii V.

    1991-01-01

    A formalism for photon transport in leaf canopies with finite-dimensional scattering centers that cross shade mutually is developed. Starting from first principles, expressions for the interaction cross sections are derived. The problem of illumination by a monodirectional source is studied in detail using a successive collisions approach. A balance equation is formulated in R3 and the interaction between a leaf canopy and the adjacent atmosphere is discussed. Although the details are those relating to a leaf canopy, the formalism is equally applicable to other media where the constituents cross shade mutually such as planetary surfaces, rings and ridged-ice in polar regions, i.e., media that exhibit opposition brightening.

  13. Radiation transfer in plant canopies - Transmission of direct solar radiation and the role of leaf orientation

    NASA Technical Reports Server (NTRS)

    Verstraete, Michel M.

    1987-01-01

    Understanding the details of the interaction between the radiation field and plant structures is important climatically because of the influence of vegetation on the surface water and energy balance, but also biologically, since solar radiation provides the energy necessary for photosynthesis. The problem is complex because of the extreme variety of vegetation forms in space and time, as well as within and across plant species. This one-dimensional vertical multilayer model describes the transfer of direct solar radiation through a leaf canopy, accounting explicitly for the vertical inhomogeneities of a plant stand and leaf orientation, as well as heliotropic plant behavior. This model reproduces observational results on homogeneous canopies, but it is also well adapted to describe vertically inhomogeneous canopies. Some of the implications of leaf orientation and plant structure as far as light collection is concerned are briefly reviewed.

  14. Diel growth cycle of isolated leaf discs analyzed with a novel, high-throughput three-dimensional imaging method is identical to that of intact leaves.

    PubMed

    Biskup, Bernhard; Scharr, Hanno; Fischbach, Andreas; Wiese-Klinkenberg, Anika; Schurr, Ulrich; Walter, Achim

    2009-03-01

    Dicot leaves grow with pronounced diel (24-h) cycles that are controlled by a complex network of factors. It is an open question to what extent leaf growth dynamics are controlled by long-range or by local signals. To address this question, we established a stereoscopic imaging system, GROWSCREEN 3D, which quantifies surface growth of isolated leaf discs floating on nutrient solution in wells of microtiter plates. A total of 458 leaf discs of tobacco (Nicotiana tabacum) were cut at different developmental stages, incubated, and analyzed for their relative growth rates. The camera system was automatically displaced across the array of leaf discs; visualization and camera displacement took about 12 s for each leaf disc, resulting in a time interval of 1.5 h for consecutive size analyses. Leaf discs showed a comparable diel leaf growth cycle as intact leaves but weaker peak growth activity. Hence, it can be concluded that the timing of leaf growth is regulated by local rather than by systemic control processes. This conclusion was supported by results from leaf discs of Arabidopsis (Arabidopsis thaliana) Landsberg erecta wild-type plants and starch-free1 mutants. At night, utilization of transitory starch leads to increased growth of Landsberg erecta wild-type discs compared with starch-free1 discs. Moreover, the decrease of leaf disc growth when exposed to different concentrations of glyphosate showed an immediate dose-dependent response. Our results demonstrate that a dynamic leaf disc growth analysis as we present it here is a promising approach to uncover the effects of internal and external cues on dicot leaf development. PMID:19168641

  15. Spring leaf phenology and the diurnal temperature range in a temperate maple forest

    NASA Astrophysics Data System (ADS)

    Hanes, Jonathan M.

    2014-03-01

    Spring leaf phenology in temperate climates is intricately related to numerous aspects of the lower atmosphere [e.g., surface energy balance, carbon flux, humidity, the diurnal temperature range (DTR)]. To further develop and improve the accuracy of ecosystem and climate models, additional investigations of the specific nature of the relationships between spring leaf phenology and various ecosystem and climate processes are required in different environments. This study used visual observations of maple leaf phenology, below-canopy light intensities, and micrometeorological data collected during the spring seasons of 2008, 2009, and 2010 to examine the potential influence of leaf phenology on a seasonal transition in the trend of the DTR. The timing of a reversal in the DTR trend occurred near the time when the leaves were unfolding and expanding. The results suggest that the spring decline in the DTR can be attributed primarily to the effect of canopy closure on daily maximum temperature. These findings improve our understanding of the relationship between leaf phenology and the diurnal temperature range in temperate maple forests during the spring. They also demonstrate the necessity of incorporating accurate phenological data into ecosystem and climate models and warrant a careful examination of the extent to which canopy phenology is currently incorporated into existing models.

  16. Comparison of hyperspectral retrievals with vegetation water indices for leaf and canopy water content

    NASA Astrophysics Data System (ADS)

    Hunt, E. Raymond, Jr.; Daughtry, Craig S. T.; Qu, John J.; Wang, Lingli; Hao, Xianjun

    2011-09-01

    Leaf and canopy water contents provide information for leaf area index, vegetation biomass, and wildfire fuel moisture content. Hyperspectral retrievals of leaf and canopy water content are determined from the relationship of spectral reflectance and the specific absorption coefficient of water over the wavelength range of a water absorption feature. Vegetation water indices such as the Normalized Difference Water Index [NDWI = (R850 - R1240)/(R850 + R1240)] and Normalized Difference Infrared Index [NDII = (R850 - R1650)/(R850 + R1650)] may be calculated from multispectral sensors such as Landsat Thematic Mapper, SPOT HRG, or MODIS. Predicted water contents from hyperspectral data were much greater than measured water contents for both leaves and canopies. Furthermore, simulated spectral reflectances from the PROSPECT and SAIL models also had greater retrieved leaf and canopy water contents compared to the inputs. Used simply as an index correlated to leaf and canopy water contents, hyperspectral retrievals had better predictive capability than NDII or NDWI. Atmospheric correction algorithms estimate canopy water content in order to estimate the amount of water vapor. These results indicate that estimated canopy water contents should have a systematic bias, even though this bias does not affect retrieved surface reflectances from hyperspectral data. Field campaigns in a variety of vegetation functional types are needed to calibrate both hyperspectral retrievals and vegetation water indices.

  17. Modeling light and temperature effects on leaf emergence in wheat and barley

    NASA Technical Reports Server (NTRS)

    Volk, T.; Bugbee, B.

    1991-01-01

    Phenological development affects canopy structure, radiation interception, and dry matter production; most crop simulation models therefore incorporate leaf emergence rate as a basic parameter. A recent study examined leaf emergence rate as a function of temperature and daylength among wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.) cultivars. Leaf emergence rate and phyllochron were modeled as functions of temperature alone, daylength alone, and the interaction between temperature and daylength. The resulting equations contained an unwieldy number of constants. Here we simplify by reducing the constants by > 70%, and show leaf emergence rate as a single response surface with temperature and daylength. In addition, we incorporate the effect of photosynthetic photon flux into the model. Generic fits for wheat and barley show cultivar differences less than +/- 5% for wheat and less than +/- 10% for barley. Barley is more sensitive to daylength changes than wheat for common environmental values of daylength, which may be related to the difference in sensitivity to daylength between spring and winter cultivars. Differences in leaf emergence rate between cultivars can be incorporated into the model by means of a single, nondimensional factor for each cultivar.

  18. Modeling light and temperature effects on leaf emergence in wheat and barley.

    PubMed

    Volk, T; Bugbee, B

    1991-01-01

    Phenological development affects canopy structure, radiation interception, and dry matter production; most crop simulation models therefore incorporate leaf emergence rate as a basic parameter. A recent study examined leaf emergence rate as a function of temperature and daylength among wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.) cultivars. Leaf emergence rate and phyllochron were modeled as functions of temperature alone, daylength alone, and the interaction between temperature and daylength. The resulting equations contained an unwieldy number of constants. Here we simplify by reducing the constants by > 70%, and show leaf emergence rate as a single response surface with temperature and daylength. In addition, we incorporate the effect of photosynthetic photon flux into the model. Generic fits for wheat and barley show cultivar differences less than +/- 5% for wheat and less than +/- 10% for barley. Barley is more sensitive to daylength changes than wheat for common environmental values of daylength, which may be related to the difference in sensitivity to daylength between spring and winter cultivars. Differences in leaf emergence rate between cultivars can be incorporated into the model by means of a single, nondimensional factor for each cultivar. PMID:11537630

  19. The failure of the Penman-Monteith equation in explaining leaf transpiration

    NASA Astrophysics Data System (ADS)

    Schymanski, Stanislaus J.; Or, Dani

    2016-04-01

    The vast majority of current global land surface models, hydrological models and inverse approaches to deduce evaporation from remote sensing data employ an analytical solution for the latent heat flux from plant leaves derived by Monteith (1965), based on an earlier formulation for a wet surface by Penman (1948). This so-called Penman-Monteith (PM) equation was most commonly evaluated at the canopy scale, where aerodynamic and canopy resistance to water vapour are difficult to estimate, leading to various empirical corrections when scaling from leaf to canopy. Here we evaluated the PM equation directly at the leaf scale, using a controlled, insulated wind tunnel and artificial leaves with pre-defined stomatal conductance. Experimental results were consistent with a detailed leaf energy balance model, but we measured consistent deviations from PM-predicted fluxes, which pointed to fundamental problems with the PM equation. Detailed analysis of the derivation by Monteith (1965) and later amendments revealed inconsistencies concerning the effect of stomata and the two-sided exchange of sensible heat. A corrected set of analytical solutions for leaf temperature as well as latent and sensible heat flux is presented and comparison with the original PM equation indicates a major improvement in reproducing experimental results at the leaf scale. The inconsistencies in the original PM equation and its failure to reproduce experimental results at the leaf scale (for which it was originally derived) lets us conclude that the PM equation does not constitute an accurate representation of atmospheric forcing on transpiration and should be regarded as a semi-empirical equation.

  20. Use of thermal imaging to determine leaf conductance along a canopy gradient in European beech (Fagus sylvatica).

    PubMed

    Reinert, Stefan; Bögelein, Rebekka; Thomas, Frank M

    2012-03-01

    Using an infrared camera, we measured the leaf temperature across different canopy positions of a 23-m-tall deciduous forest tree (Fagus sylvatica L.) including typical sun and shade leaves as well as intermediate leaf forms, which differed significantly in specific leaf area (SLA). We calculated a temperature index (I(G)) and a crop water stress index (CWSI) using the surface temperatures of wet and dry reference leaves. Additional indices were computed using air temperature plus 5 °C (I(G) + 5, CWSI + 5) as dry references. The minimum temperature of the wet leaf and the maximum temperature of the dry leaf proved to be most suitable as reference values. We correlated the temperature indices with leaf area-related conductance to water vapor (g(L)) using porometry at the leaf level and using xylem sap flow at the branch level. At the leaf and at the branch level, I(G) and CWSI were equally well suited as proxies of g(L), whereas the relationships of I(G) + 5 and CWSI + 5 with g(L) were only weak or even insignificant. At the leaf level, the correlations of I(G) and CWSI with g(L) were significant in all parts of the crown. The slopes of g(L) vs. I(G) and CWSI did not differ significantly among the crown parts; this indicates that they were not influenced by SLA or irradiance. At the branch level, close correlations (r > 0.8) were found between temperature indices and g(L) across the crown. These results demonstrate that satisfactory relationships between temperature indices and g(L) can be established in tall trees even in those canopy parts that are exposed to relatively low levels of irradiance and exhibit relatively low values of g(L). PMID:22427372

  1. 3D leaf water content mapping using terrestrial laser scanner backscatter intensity with radiometric correction

    NASA Astrophysics Data System (ADS)

    Zhu, Xi; Wang, Tiejun; Darvishzadeh, Roshanak; Skidmore, Andrew K.; Niemann, K. Olaf

    2015-12-01

    Leaf water content (LWC) plays an important role in agriculture and forestry management. It can be used to assess drought conditions and wildfire susceptibility. Terrestrial laser scanner (TLS) data have been widely used in forested environments for retrieving geometrically-based biophysical parameters. Recent studies have also shown the potential of using radiometric information (backscatter intensity) for estimating LWC. However, the usefulness of backscatter intensity data has been limited by leaf surface characteristics, and incidence angle effects. To explore the idea of using LiDAR intensity data to assess LWC we normalized (for both angular effects and leaf surface properties) shortwave infrared TLS data (1550 nm). A reflectance model describing both diffuse and specular reflectance was applied to remove strong specular backscatter intensity at a perpendicular angle. Leaves with different surface properties were collected from eight broadleaf plant species for modeling the relationship between LWC and backscatter intensity. Reference reflectors (Spectralon from Labsphere, Inc.) were used to build a look-up table to compensate for incidence angle effects. Results showed that before removing the specular influences, there was no significant correlation (R2 = 0.01, P > 0.05) between the backscatter intensity at a perpendicular angle and LWC. After the removal of the specular influences, a significant correlation emerged (R2 = 0.74, P < 0.05). The agreement between measured and TLS-derived LWC demonstrated a significant reduction of RMSE (root mean square error, from 0.008 to 0.003 g/cm2) after correcting for the incidence angle effect. We show that it is possible to use TLS to estimate LWC for selected broadleaved plants with an R2 of 0.76 (significance level α = 0.05) at leaf level. Further investigations of leaf surface and internal structure will likely result in improvements of 3D LWC mapping for studying physiology and ecology in vegetation.

  2. Improving and validating 3D models for the leaf energy balance in canopy-scale problems with complex geometry

    NASA Astrophysics Data System (ADS)

    Bailey, B.; Stoll, R., II; Miller, N. E.; Pardyjak, E.; Mahaffee, W.

    2014-12-01

    Plants cover the majority of Earth's land surface, and thus play a critical role in the surface energy balance. Within individual plant communities, the leaf energy balance is a fundamental component of most biophysical processes. Absorbed radiation drives the energy balance and provides the means by which plants produce food. Available energy is partitioned into sensible and latent heat fluxes to determine surface temperature, which strongly influences rates of metabolic activity and growth. The energy balance of an individual leaf is coupled with other leaves in the community through longwave radiation emission and advection through the air. This complex coupling can make scaling models from leaves to whole-canopies difficult, specifically in canopies with complex, heterogeneous geometries. We present a new three-dimensional canopy model that simultaneously resolves sub-tree to whole-canopy scales. The model provides spatially explicit predictions of net radiation exchange, boundary-layer and stomatal conductances, evapotranspiration rates, and ultimately leaf surface temperature. The radiation model includes complex physics such as anisotropic emission and scattering. Radiation calculations are accelerated by leveraging graphics processing unit (GPU) technology, which allows canopy-scale problems to be performed on a standard desktop workstation. Since validating the three-dimensional distribution of leaf temperature can be extremely challenging, we used several independent measurement techniques to quantify errors in measured and modeled values. When compared with measured leaf temperatures, the model gave a mean error of about 2°C, which was close to the estimated measurement uncertainty.

  3. DIGITAL IMAGE ANALYSIS OF ZOSTERA MARINA LEAF INJURY

    EPA Science Inventory

    Current methods for assessing leaf injury in Zostera marina (eelgrass) utilize subjective indexes for desiccation injury and wasting disease. Because of the subjective nature of these measures, they are inherently imprecise making them difficult to use in quantifying complex leaf...

  4. Leaf water and plant wax hydrogen isotopes in a European sample network

    NASA Astrophysics Data System (ADS)

    Nelson, D. B.; Kahmen, A.

    2014-12-01

    a more focused framework for understanding the environmental signal captured in leaf waxes, and will be used to refine models of isotopic processes within plants as well as the impact of these processes on surface and atmospheric water.

  5. Effects of heavy metal pollution on oak leaf microorganisms

    SciTech Connect

    Bewley, R.J.F.

    1980-12-01

    During the growing season, comparisons wer made of the leaf surface microflora of (i) two groups of mature oak trees, one in the vicinity of a smelting complex contaminated by heavy metals and the other at a relatively uncontaminated site, and (ii) two groups of oak saplings at the uncontaminated site, one of which was sprayed with zinc, lead, and cadmium to simulate the heavy metal pollution from the smelter without the complicating effects of other pollutants. Total viable counts of bacteria, yeasts, and filamentous fungi (isolated by leaf washing) were generally little affected by the spraying treatment, whereas polluted leaves of mature trees supported fewer bacteria compared with leaves of mature trees at the uncontaminated site. Numbers of pigmented yeasts were lower on polluted oaks and on metal-dosed saplings compared with their respective controls. Polluted leaves of mature trees supported both greater numbers of Aureobasidium pullulans and Cladosporium spp. and a greater percentage of metal-tolerant fungi compared with oak leaves at the uncontaminated site. There were no significant overall differences in the degree of mycelial growth between the two groups of saplings or the mature trees.

  6. Tackling regional climate change by leaf albedo bio-geoengineering.

    PubMed

    Ridgwell, Andy; Singarayer, Joy S; Hetherington, Alistair M; Valdes, Paul J

    2009-01-27

    The likelihood that continuing greenhouse-gas emissions will lead to an unmanageable degree of climate change has stimulated the search for planetary-scale technological solutions for reducing global warming ("geoengineering"), typically characterized by the necessity for costly new infrastructures and industries. We suggest that the existing global infrastructure associated with arable agriculture can help, given that crop plants exert an important influence over the climatic energy budget because of differences in their albedo (solar reflectivity) compared to soils and to natural vegetation. Specifically, we propose a "bio-geoengineering" approach to mitigate surface warming, in which crop varieties having specific leaf glossiness and/or canopy morphological traits are specifically chosen to maximize solar reflectivity. We quantify this by modifying the canopy albedo of vegetation in prescribed cropland areas in a global-climate model, and thereby estimate the near-term potential for bio-geoengineering to be a summertime cooling of more than 1 degrees C throughout much of central North America and midlatitude Eurasia, equivalent to seasonally offsetting approximately one-fifth of regional warming due to doubling of atmospheric CO(2). Ultimately, genetic modification of plant leaf waxes or canopy structure could achieve greater temperature reductions, although better characterization of existing intraspecies variability is needed first. PMID:19147356

  7. Effects of Heavy Metal Pollution on Oak Leaf Microorganisms

    PubMed Central

    Bewley, Richard J. F.

    1980-01-01

    During the growing season, comparisons were made of the leaf surface microflora of (i) two groups of mature oak trees, one in the vicinity of a smelting complex contaminated by heavy metals and the other at a relatively uncontaminated site, and (ii) two groups of oak saplings at the uncontaminated site, one of which was sprayed with zinc, lead, and cadmium to simulate the heavy metal pollution from the smelter without the complicating effects of other pollutants. Total viable counts of bacteria, yeasts, and filamentous fungi (isolated by leaf washing) were generally little affected by the spraying treatment, whereas polluted leaves of mature trees supported fewer bacteria compared with leaves of mature trees at the uncontaminated site. Numbers of pigmented yeasts were lower on polluted oaks and on metal-dosed saplings compared with their respective controls. Polluted leaves of mature trees supported both greater numbers of Aureobasidium pullulans and Cladosporium spp. and a greater percentage of metal-tolerant fungi compared with oak leaves at the uncontaminated site. There were no significant overall differences in the degree of mycelial growth between the two groups of saplings or the mature trees. PMID:16345669

  8. Leaf Stomata as Bioindicators: Stimulating Student Research

    ERIC Educational Resources Information Center

    Case, Steven B.

    2006-01-01

    Stomata are the pores on leaves through which carbon dioxide, oxygen, and water vapor are exchanged with the atmosphere. Researchers have found that leaf stomatal densities change in response to several environmental variables, including humidity, light intensity, and atmospheric levels of carbon dioxide, a greenhouse gas (Van Der Burgh, Dilcher,…

  9. Simulation rice leaf reflectance and its inversion

    NASA Astrophysics Data System (ADS)

    Li, Yunmei; Ni, Shaoxiang; Huang, Jinfeng

    2003-06-01

    To improve our understanding of photon transporting inside leaves, and hence improve the accuracy of yield estimating and growth monitoring of rice by remotely sensed data, we simulated rice leaf reflectance by PROSPECT model. The experiment, which were referred to as the late rice experiment, were conducted at Zhejiang University in 1999 and 2000 with one species of rice (which is called Xiushui 63); In 1999 the rice was planted normally, but in 2000 it was fertilized in three different levels (low, medium and high). Leaf spectrum (reflectance and transmittance), biochemical concentration such as chlorophyll, protein, cellulose, lignin and water content, and leaf area were measured during the experiment. By the PROSPECT model, we simulated leaf reflectance on four days" data set in 1999 and one day"s data set of three fertilizations in 2000. The correlation coefficients between actual and simulated values are more than 0.995, the RMSE values are less than 0.0212. On the other hand, the model has been inversed to estimate chlorophyll concentration. Compared with actual value, the comparative errors are less than 10%.

  10. Leafminers help us understand leaf hydraulic design.

    PubMed

    Nardini, Andrea; Raimondo, Fabio; Lo Gullo, Maria A; Salleo, Sebastiano

    2010-07-01

    Leaf hydraulics of Aesculus hippocastanum L. were measured over the growing season and during extensive leaf mining by the larvae of an invasive moth (Cameraria ohridella Deschka et Dimic) that specifically destroy the palisade tissue. Leaves showed seasonal changes in hydraulic resistance (R(lamina)) which were related to ontogeny. After leaf expansion was complete, the hydraulic resistance of leaves and the partitioning of resistances between vascular and extra-vascular compartments remained unchanged despite extensive disruption of the palisade by leafminers (up to 50%). This finding suggests that water flow from the petiole to the evaporation sites might not directly involve the palisade cells. The analysis of the temperature dependence of R(lamina) in terms of Q(10) revealed that at least one transmembrane step was involved in water transport outside the leaf vasculature. Anatomical analysis suggested that this symplastic step may be located at the bundle sheath where the apoplast is interrupted by hydrophobic thickening of cell walls. Our findings offer some support to the view of a compartmentalization of leaves into well-organized water pools so that the transpiration stream would involve veins, bundle sheath and spongy parenchyma, while the palisade tissue would be largely by-passed with the possible advantage of protecting cells from short-term fluctuations in water status. PMID:20199625

  11. 7 CFR 29.1030 - Leaf structure.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf structure. 29.1030 Section 29.1030 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE COMMODITY STANDARDS AND STANDARD CONTAINER REGULATIONS TOBACCO INSPECTION Standards Official...

  12. 7 CFR 29.2278 - Leaf structure.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 2 2014-01-01 2014-01-01 false Leaf structure. 29.2278 Section 29.2278 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE COMMODITY STANDARDS AND STANDARD CONTAINER REGULATIONS TOBACCO INSPECTION Standards Official...

  13. 7 CFR 29.3035 - Leaf structure.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 2 2014-01-01 2014-01-01 false Leaf structure. 29.3035 Section 29.3035 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE COMMODITY STANDARDS AND STANDARD CONTAINER REGULATIONS TOBACCO INSPECTION Standards Official...

  14. 7 CFR 29.6023 - Leaf structure.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 2 2014-01-01 2014-01-01 false Leaf structure. 29.6023 Section 29.6023 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE COMMODITY STANDARDS AND STANDARD CONTAINER REGULATIONS TOBACCO INSPECTION Standards Definitions...

  15. 7 CFR 29.3527 - Leaf structure.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 2 2014-01-01 2014-01-01 false Leaf structure. 29.3527 Section 29.3527 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE COMMODITY STANDARDS AND STANDARD CONTAINER REGULATIONS TOBACCO INSPECTION Standards Official...

  16. 7 CFR 29.2530 - Leaf structure.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 2 2014-01-01 2014-01-01 false Leaf structure. 29.2530 Section 29.2530 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE COMMODITY STANDARDS AND STANDARD CONTAINER REGULATIONS TOBACCO INSPECTION Standards Official...

  17. 7 CFR 29.1030 - Leaf structure.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 2 2014-01-01 2014-01-01 false Leaf structure. 29.1030 Section 29.1030 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE COMMODITY STANDARDS AND STANDARD CONTAINER REGULATIONS TOBACCO INSPECTION Standards Official...

  18. New leaf diseases of barley in Egypt.

    PubMed

    Mehiar, F F; El-Deen, E; Wasfy, H; El-Samra, I A

    1976-01-01

    Leaf diseases of barley were observed also in Egypt. From leaves of barley were isolated: Helminthosporium teres, H. gramineum, Stemphylium vesicarium, Alternaria triticina, Vlocladium chartarum, Acnemonium kiliense, Stemphylium spec. accompanied with the Pleospora stage. Inoculations on both attached and detached leaves showed that all the tested fungi were pathogenic, except Acremonium kiliense and Ulocladium chartarum. PMID:1037183

  19. Reactive oxygen species in leaf abscission signaling

    PubMed Central

    Sakamoto, Masaru; Munemura, Ikuko; Tomita, Reiko

    2008-01-01

    Reactive oxygen species (ROS) are produced in response to many environmental stresses, such as UV, chilling, salt and pathogen attack. These stresses also accompany leaf abscission in some plants, however, the relationship between these stresses and abscission is poorly understood. In our recent report, we developed an in vitro abscission system that reproduces stress-induced pepper leaf abscission in planta. Using this system, we demonstrated that continuous production of hydrogen peroxide (H2O2) is involved in leaf abscission signaling. Continuous H2O2 production is required to induce expression of the cell wall-degrading enzyme, cellulase and functions downstream of ethylene in abscission signaling. Furthermore, enhanced production of H2O2 occurs at the execution phase of abscission, suggesting that H2O2 also plays a role in the cell-wall degradation process. These data suggest that H2O2 has several roles in leaf abscission signaling. Here, we propose a model for these roles. PMID:19704438

  20. Bioinformatic pipelines in Python with Leaf

    PubMed Central

    2013-01-01

    Background An incremental, loosely planned development approach is often used in bioinformatic studies when dealing with custom data analysis in a rapidly changing environment. Unfortunately, the lack of a rigorous software structuring can undermine the maintainability, communicability and replicability of the process. To ameliorate this problem we propose the Leaf system, the aim of which is to seamlessly introduce the pipeline formality on top of a dynamical development process with minimum overhead for the programmer, thus providing a simple layer of software structuring. Results Leaf includes a formal language for the definition of pipelines with code that can be transparently inserted into the user’s Python code. Its syntax is designed to visually highlight dependencies in the pipeline structure it defines. While encouraging the developer to think in terms of bioinformatic pipelines, Leaf supports a number of automated features including data and session persistence, consistency checks between steps of the analysis, processing optimization and publication of the analytic protocol in the form of a hypertext. Conclusions Leaf offers a powerful balance between plan-driven and change-driven development environments in the design, management and communication of bioinformatic pipelines. Its unique features make it a valuable alternative to other related tools. PMID:23786315

  1. Toxicity evaluation of diazinon contaminated leaf litter

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Diazinon is an organophosphate pesticide with widespread use on a variety of agricultural crops. Because of its use, diazinon is a potential contributor to non-point source contamination of aquatic environments. A prominent feature within these aquatic environments includes leaf litter, especially...

  2. LONG LEAF PINE RESTORATION PROJECT MX974390

    EPA Science Inventory

    There are two primary goals for managing the Dantzler Coastal Preserve: 1) Protect and enhance the flora and fauna of the estuarine marsh; and 2) Manage the upland portion by restoring the long leaf pine ecosystem. Results from this project will improve the wetlands and water...

  3. Winter leaf reddening in 'evergreen' species.

    PubMed

    Hughes, Nicole M

    2011-05-01

    Leaf reddening during autumn in senescing, deciduous tree species has received widespread attention from the public and in the scientific literature, whereas leaf reddening in evergreen species during winter remains largely ignored. Winter reddening can be observed in evergreen herbs, shrubs, vines and trees in Mediterranean, temperate, alpine, and arctic regions, and can persist for several months before dissipating with springtime warming. Yet, little is known about the functional significance of this colour change, or why it occurs in some species but not others. Here, the biochemistry, physiology and ecology associated with winter leaf reddening are reviewed, with special focus on its possible adaptive function. Photoprotection is currently the favoured hypothesis for winter reddening, but alternative explanations have scarcely been explored. Intraspecific reddening generally increases with sunlight incidence, and may also accompany photosynthetic inferiority in photosynthetically 'weak' (e.g. low-nitrogen) individuals. Red leaves tend to show symptoms of shade acclimation relative to green, consistent with a photoprotective function. However, winter-red and winter-green species often cohabitate the same high-light environments, and exhibit similar photosynthetic capacities. The factors dictating interspecific winter leaf colouration therefore remain unclear. Additional outstanding questions and future directions are also highlighted, and possible alternative functions of winter reddening discussed. PMID:21375534

  4. Wax Layers on Cosmos bipinnatus Petals Contribute Unequally to Total Petal Water Resistance1[OPEN

    PubMed Central

    Buschhaus, Christopher; Hager, Dana; Jetter, Reinhard

    2015-01-01

    Cuticular waxes coat all primary aboveground plant organs as a crucial adaptation to life on land. Accordingly, the properties of waxes have been studied in much detail, albeit with a strong focus on leaf and fruit waxes. Flowers have life histories and functions largely different from those of other organs, and it remains to be seen whether flower waxes have compositions and physiological properties differing from those on other organs. This work provides a detailed characterization of the petal waxes, using Cosmos bipinnatus as a model, and compares them with leaf and stem waxes. The abaxial petal surface is relatively flat, whereas the adaxial side consists of conical epidermis cells, rendering it approximately 3.8 times larger than the projected petal area. The petal wax was found to contain unusually high concentrations of C22 and C24 fatty acids and primary alcohols, much shorter than those in leaf and stem waxes. Detailed analyses revealed distinct differences between waxes on the adaxial and abaxial petal sides and between epicuticular and intracuticular waxes. Transpiration resistances equaled 3 × 104 and 1.5 × 104 s m−1 for the adaxial and abaxial surfaces, respectively. Petal surfaces of C. bipinnatus thus impose relatively weak water transport barriers compared with typical leaf cuticles. Approximately two-thirds of the abaxial surface water barrier was found to reside in the epicuticular wax layer of the petal and only one-third in the intracuticular wax. Altogether, the flower waxes of this species had properties greatly differing from those on vegetative organs. PMID:25413359

  5. Morphology of leaves cuticle by fringe projection

    NASA Astrophysics Data System (ADS)

    Martínez, Amalia; Rayas Alvarez, J. A.; Cordero, Raúl; Balieiro R., Daniela

    2011-10-01

    The development of this work is important in the morphological study of plant parts, specifically in the study of the cuticle of fruits or leaves. The implemented optical technique for fringe projection can identify potential fracture zones which damage the presentation of the fruits impacting business as well as producing them. Specifically, we obtained information on the thickness of a cuticle corresponding to the abaxial surface of a leaf of apple (Malus domestica) of the variety Golden Delicious.

  6. Aftereffects of low and high temperature pretreatment on leaf resistance, transpiration, and leaf temperature in xanthium.

    PubMed

    Drake, B G; Salisbury, F B

    1972-11-01

    Leaf resistance for water vapor (total diffusion resistance minus boundary layer resistance), transpiration, and leaf temperature were measured in attached leaves of greenhouse-grown Xanthium strumarium L. plants that had been pretreated for 72 hours with high (40 C day, 35 C night), or low (10 C day, 5 C night) air temperatures. Measurements were made in a wind tunnel at light intensity of 1.15 cal cm(-2) min(-1), air temperatures between 5 and 45 C, and wind speed of 65 cm sec(-1). Leaf resistances in low temperature pretreated plants were higher (8 to 27 sec cm(-1)) than in controls or high temperature pretreated plants (0.5 to 3 sec cm(-1)) at leaf temperatures between 5 and 25 C. Thus, the pretreatment influenced stomatal aperture. PMID:16658219

  7. A Journey Through a Leaf: Phenomics Analysis of Leaf Growth in Arabidopsis thaliana

    PubMed Central

    Vanhaeren, Hannes; Gonzalez, Nathalie; Inzé, Dirk

    2015-01-01

    In Arabidopsis, leaves contribute to the largest part of the aboveground biomass. In these organs, light is captured and converted into chemical energy, which plants use to grow and complete their life cycle. Leaves emerge as a small pool of cells at the vegetative shoot apical meristem and develop into planar, complex organs through different interconnected cellular events. Over the last decade, numerous phenotyping techniques have been developed to visualize and quantify leaf size and growth, leading to the identification of numerous genes that contribute to the final size of leaves. In this review, we will start at the Arabidopsis rosette level and gradually zoom in from a macroscopic view on leaf growth to a microscopic and molecular view. Along this journey, we describe different techniques that have been key to identify important events during leaf development and discuss approaches that will further help unraveling the complex cellular and molecular mechanisms that underlie leaf growth. PMID:26217168

  8. Relating Leaf Nitrogen, Leaf Photosynthesis and Canopy CO2 Exchange in a Temperate Winter Barley Field

    NASA Astrophysics Data System (ADS)

    Jensen, R.; Boegh, E.; Herbst, M.; Friborg, T.

    2012-12-01

    Net exchange of CO2 between the atmosphere and the soil-vegetation interface (NEE) is controlled by a wide range of biochemical and biophysical processes where leaf photosynthesis is often the most important. In mechanistically and physically based photosynthesis models (e.g. Farquhar et al. 1980) leaf nutrient status is a limiting factor for the photosynthetic capacity since it is implicitly incorporated through the parameters of maximum rate of carboxylation of CO2 (Vcmax) and the maximum rate of electron transport (Jmax). These are closely related to leaf nitrogen concentration (Na) and leaf chlorophyll content (Cab) and often show a characteristic seasonal dynamic. When simulating CO2 exchange, model outputs are sensitive to leaf photosynthetic capacity, which is labour consuming to verify through field measurements. A less time consuming method is to measure leaf "greenness" (SPAD), which is closely related to chlorophyll content and thus photosynthetic capacity. In the present study field measurements of leaf photosynthesis (LI-6400, LICOR Inc.), leaf reflectance (SPAD-502, Minolta), and LAI (LAI-2000, LICOR Inc.) were conducted on agricultural fields in Western Denmark during one growing season. The leaf photosynthesis measurements provided the basis for estimating photosynthetic capacity. SPAD measurements and LAI was measured with a higher spatial and temporal resolution. SPAD readings were calibrated against Cab and Na analyzed on leaf material in the laboratory and later correlated to photosynthetic capacity. These data were used to parameterize a coupled photosynthesis and stomatal model that was run for the growing season 2012 to estimate NEE. As a part of the hydrological observatory HOBE (hobe.dk), fluxes of greenhouse gasses are continuously measured by eddy covariance systems at three field sites in the Skjern River Catchment, Western Denmark, providing the basis for estimating the exchange of energy, water vapour, and CO2 on canopy scale. One of

  9. Leaf Areas And Spectral Properties Of Slash Pine

    NASA Technical Reports Server (NTRS)

    Curran, Paul J.; Dungan, Jennifer L.; Gholz, Henry L.

    1993-01-01

    NASA technical memorandum describes experiments to test feasibility of estimating seasonal leaf areas of forest canopies from spectral radiances measured by remote instruments. Accurate estimates of seasonal leaf areas of forests necessary for studies of seasonal exchanges of energy between forest canopies and atmosphere. Potential use of remote sensing in estimating seasonal changes in leaf area index (LAI).

  10. 7 CFR 29.2438 - Thin Leaf (C Group).

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... Fair Light-brown Thin Leaf. Thin to medium body, mature to ripe, close, lean in oil, inelastic, weak... Light-brown Thin Leaf. Thin to medium body, mature to ripe, close, lean in oil, inelastic, weak, dull... Medium-brown Thin Leaf. Thin to medium body, mature to ripe, close, lean in oil, inelastic, weak,...

  11. 7 CFR 29.2663 - Thin Leaf (C Group).

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... tolerance. C4L Fair Light-brown Thin Leaf. Thin, mature, close, lean in oil, inelastic, weak, dull finish... Thin Leaf. Thin, mature, close, lean in oil, inelastic, weak, dull finish, pale color intensity, narrow... tolerance. C4F Fair Medium-brown Thin Leaf. Thin, mature, close, lean in oil, inelastic, weak, dull...

  12. OKRA-LEAF AS A POTENTIAL FOR WHITEFLY CONTROL

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We compared smooth-leaf okra- and normal-leaf upland cotton (Gossypium hirsutum L.) cultivars for susceptibility to colonization by Bemisia tabaci (Gennadius) biotype B. Seven field studies were conducted, five at Holtville, CA and two at Maricopa, AZ during 1996 to 2000. Okra-leaf cultivars as a gr...

  13. 7 CFR 29.1163 - Smoking Leaf (H Group).

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... over 10 percent may be waste. H6F—Poor Quality Orange Smoking Leaf Mellow, open leaf structure, medium..., 70 percent; injury tolerance 30 percent, of which not over 10 percent may be waste. H6FR—Poor Quality... percent, of which not over 10 percent may be waste. H6K—Poor Quality Variegated Smoking Leaf Mellow,...

  14. 7 CFR 29.1163 - Smoking Leaf (H Group).

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... over 10 percent may be waste. H6F—Poor Quality Orange Smoking Leaf Mellow, open leaf structure, medium..., 70 percent; injury tolerance 30 percent, of which not over 10 percent may be waste. H6FR—Poor Quality... percent, of which not over 10 percent may be waste. H6K—Poor Quality Variegated Smoking Leaf Mellow,...

  15. Turbine rotor-stator leaf seal and related method

    DOEpatents

    Herron, William Lee; Butkiewicz, Jeffrey John

    2003-01-01

    A seal assembly for installation between rotating and stationary components of a machine includes a first plurality of leaf spring segments secured to the stationary component in a circumferential array surrounding the rotating component, the leaf spring segments each having a radial mounting portion and a substantially axial sealing portion, the plurality of leaf spring segments shingled in a circumferential direction.

  16. 7 CFR 51.1220 - Leaf or limb rub injury.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf or limb rub injury. 51.1220 Section 51.1220... STANDARDS) United States Standards for Grades of Peaches Definitions § 51.1220 Leaf or limb rub injury. “Leaf or limb rub injury” means that the scarring is not smooth, not light colored, or aggregates...

  17. Resistance to Cucurbit Leaf Crumple Virus in Melon

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cucurbit leaf crumple virus (CuLCrV) is a geminivirus common in melons (Cucumis melo L.) planted from July through September in the desert southwest U.S.A. Symptoms include chlorotic leaf spots and terminal buds, leaf curling and crumpling and interveinal yellowing, and plants may be stunted in size...

  18. The potential of biomonitoring of air quality using leaf characteristics of white willow (Salix alba L.).

    PubMed

    Wuytack, Tatiana; Verheyen, Kris; Wuyts, Karen; Kardel, Fatemeh; Adriaenssens, Sandy; Samson, Roeland

    2010-12-01

    In this study, we assess the potential of white willow (Salix alba L.) as bioindicator for monitoring of air quality. Therefore, shoot biomass, specific leaf area, stomatal density, stomatal pore surface, and stomatal resistance were assessed from leaves of stem cuttings. The stem cuttings were introduced in two regions in Belgium with a relatively high and a relatively low level of air pollution, i.e., Antwerp city and Zoersel, respectively. In each of these regions, nine sampling points were selected. At each sampling point, three stem cuttings of white willow were planted in potting soil. Shoot biomass and specific leaf area were not significantly different between Antwerp city and Zoersel. Microclimatic differences between the sampling points may have been more important to plant growth than differences in air quality. However, stomatal pore surface and stomatal resistance of white willow were significantly different between Zoersel and Antwerp city. Stomatal pore surface was 20% lower in Antwerp city due to a significant reduction in both stomatal length (-11%) and stomatal width (-14%). Stomatal resistance at the adaxial leaf surface was 17% higher in Antwerp city because of the reduction in stomatal pore surface. Based on these results, we conclude that stomatal characteristics of white willow are potentially useful indicators for air quality. PMID:20033771

  19. On the Radiative Transfer Based Remote Sensing of Forest Structure and Leaf Biochemistry (Invited)

    NASA Astrophysics Data System (ADS)

    Knyazikhin, Y.

    2013-12-01

    The architecture of individual trees, their spatial distribution and leaf optical properties are among key variables that determine angular patterns of reflected radiation, or the bidirectional reflectance factor (BRF), which is measured by air- and satellite-borne sensors. Forest shortwave radiative response is described by the three-dimensional radiative transfer equation. The interaction cross-section that appears in this equation is treated as wavelength independent considering the size of the scattering elements (leaves, branches, twigs, etc.) relative to the wavelength of solar radiation. Although the scattering and absorption processes are different at different wavelengths, the interaction probabilities for photons in vegetation media are determined by the structure of the canopy rather than photon frequency or the optics of the canopy. This feature results in a unique spectrally invariant behavior for a vegetation canopy bounded from below by a non-reflecting surface: the BRF to leaf albedo ratio is linearly related to BRF, where the slope and intercept are the recollision and escape probabilities. These spectrally invariant (wavelength independent) parameters specify a new variable, the Directional Area Scattering Factor (DASF), which is an estimate of the fraction of leaf area inside the canopy that is visible from outside the canopy along a given direction. The DASF is determined entirely by canopy geometrical properties such as shape and size of the tree crowns, spatial distribution of trees on the ground, within-crown foliage arrangement, and properties of the leaf surfaces, and accounts for the cumulative effect of canopy structural properties at different scales on the reflectance. In dense vegetation, this variable can be directly retrieved from the reflectance spectrum without the use of canopy-reflectance models, prior knowledge, or ancillary information regarding leaf optical properties. Here we will discuss the physical basis of the spectral

  20. Diel leaf growth of soybean: a novel method to analyze two-dimensional leaf expansion in high temporal resolution based on a marker tracking approach (Martrack Leaf)

    PubMed Central

    2013-01-01

    Background We present a novel method for quantitative analysis of dicot leaf expansion at high temporal resolution. Image sequences of growing leaves were assessed using a marker tracking algorithm. An important feature of the method is the attachment of dark beads that serve as artificial landmarks to the leaf margin. The beads are mechanically constricted to the focal plane of a camera. Leaf expansion is approximated by the increase in area of the polygon defined by the centers of mass of the beads surrounding the leaf. Fluctuating illumination conditions often pose serious problems for tracking natural structures of a leaf; this problem is circumvented here by the use of the beads. Results The new method has been used to assess leaf growth in environmental situations with different illumination conditions that are typical in agricultural and biological experiments: Constant illumination via fluorescent light tubes in a climate chamber, a mix of natural and artificial illumination in a greenhouse and natural illumination of the situation on typical summer days in the field. Typical features of diel (24h) soybean leaf growth patterns were revealed in all three conditions, thereby demonstrating the general applicability of the method. Algorithms are provided to the entire community interested in using such approaches. Conclusions The implementation Martrack Leaf presented here is a robust method to investigate diel leaf growth rhythms both under natural and artificial illumination conditions. It will be beneficial for the further elucidation of genotype x environment x management interactions affecting leaf growth processes. PMID:23883317