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Sample records for availability leaf life

  1. 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

  2. MAKING LIFE CYCLE INVENTORY DATA AVAILABLE

    EPA Science Inventory

    Making Life Cycle Inventory Data Available

    Mary Ann Curran
    US EPA, National Risk Management Research Laboratory
    Address: 26 W. Martin Luther King Drive (MS-466)
    Cincinnati, OH 45268 USA
    Phone: 513-569-7782
    Fax: 513-569-7111
    E-Mail: curran.maryann@...

  3. Interspecific vs intraspecific patterns in leaf nitrogen of forest trees across nitrogen availability gradients.

    PubMed

    Dybzinski, Ray; Farrior, Caroline E; Ollinger, Scott; Pacala, Stephen W

    2013-10-01

    Leaf nitrogen content (δ) coordinates with total canopy N and leaf area index (LAI) to maximize whole-crown carbon (C) gain, but the constraints and contributions of within-species plasticity to this phenomenon are poorly understood. Here, we introduce a game theoretic, physiologically based community model of height-structured competition between late-successional tree species. Species are constrained by an increasing, but saturating, relationship between photosynthesis and leaf N per unit leaf area. Higher saturating rates carry higher fixed costs. For a given whole-crown N content, a C gain-maximizing compromise exists between δ and LAI. With greater whole-crown N, both δ and LAI increase within species. However, a shift in community composition caused by reduced understory light at high soil N availability (which competitively favors species with low leaf costs and consequent low optimal δ) counteracts the within-species response, such that community-level δ changes little with soil N availability. These model predictions provide a new explanation for the changes in leaf N per mass observed in data from three dominant broadleaf species in temperate deciduous forests of New England. Attempts to understand large-scale patterns in vegetation often omit competitive interactions and intraspecific plasticity, but here both are essential to an understanding of ecosystem-level patterns. PMID:23738827

  4. Effect of Assembly Stresses on Fatigue Life of Symmetrical 65Si7 Leaf Springs

    PubMed Central

    Arora, Vinkel Kumar; Bhushan, Gian; Aggarwal, M. L.

    2014-01-01

    The maximum stress induced plays vital role in fatigue life improvement of leaf springs. To reduce this maximum stress, leaves with different unassembled cambers are assembled by pulling against each other and a common curvature is established. This causes stress concentration or sets assembly stress in the assembled leaf springs which is subtractive from load stress in master leaf while it is additive to load stress for short leaves. By suitable combination of assembly stresses and stepping, it is possible to distribute the stress and improve the fatigue life of the leaf spring. The effect of assembly stresses on fatigue life of the leaf spring of a light commercial vehicle (LCV) has been studied. A proper combination of stepping and camber has been proposed by taking the design parameters into consideration, so that the stress in the leaves does not exceed maximum design stress. The theoretical fatigue life of the leaf springs with and without considering the assembly stresses is determined and compared with experimental life. The numbers of specimens are manufactured with proposed parameters and tested for load rate, fatigue life on a full scale leaf springs testing machine. The effect of stress range, maximum stress, and initial stress is also discussed. PMID:27433537

  5. Fatigue Life Assessment of 65Si7 Leaf Springs: A Comparative Study

    PubMed Central

    Arora, Vinkel Kumar; Bhushan, Gian; Aggarwal, M. L.

    2014-01-01

    The experimental fatigue life prediction of leaf springs is a time consuming process. The engineers working in the field of leaf springs always face a challenge to formulate alternate methods of fatigue life assessment. The work presented in this paper provides alternate methods for fatigue life assessment of leaf springs. A 65Si7 light commercial vehicle leaf spring is chosen for this study. The experimental fatigue life and load rate are determined on a full scale leaf spring testing machine. Four alternate methods of fatigue life assessment have been depicted. Firstly by SAE spring design manual approach the fatigue test stroke is established and by the intersection of maximum and initial stress the fatigue life is predicted. The second method constitutes a graphical method based on modified Goodman's criteria. In the third method codes are written in FORTRAN for fatigue life assessment based on analytical technique. The fourth method consists of computer aided engineering tools. The CAD model of the leaf spring has been prepared in solid works and analyzed using ANSYS. Using CAE tools, ideal type of contact and meshing elements have been proposed. The method which provides fatigue life closer to experimental value and consumes less time is suggested. PMID:27379327

  6. Fatigue Life Assessment of 65Si7 Leaf Springs: A Comparative Study.

    PubMed

    Arora, Vinkel Kumar; Bhushan, Gian; Aggarwal, M L

    2014-01-01

    The experimental fatigue life prediction of leaf springs is a time consuming process. The engineers working in the field of leaf springs always face a challenge to formulate alternate methods of fatigue life assessment. The work presented in this paper provides alternate methods for fatigue life assessment of leaf springs. A 65Si7 light commercial vehicle leaf spring is chosen for this study. The experimental fatigue life and load rate are determined on a full scale leaf spring testing machine. Four alternate methods of fatigue life assessment have been depicted. Firstly by SAE spring design manual approach the fatigue test stroke is established and by the intersection of maximum and initial stress the fatigue life is predicted. The second method constitutes a graphical method based on modified Goodman's criteria. In the third method codes are written in FORTRAN for fatigue life assessment based on analytical technique. The fourth method consists of computer aided engineering tools. The CAD model of the leaf spring has been prepared in solid works and analyzed using ANSYS. Using CAE tools, ideal type of contact and meshing elements have been proposed. The method which provides fatigue life closer to experimental value and consumes less time is suggested. PMID:27379327

  7. Leaf life span spectrum of tropical woody seedlings: effects of light and ontogeny and consequences for survival

    PubMed Central

    Kitajima, Kaoru; Cordero, Roberto A.; Wright, S. Joseph

    2013-01-01

    Background and Aims Leaf life span is widely recognized as a key life history trait associated with herbivory resistance, but rigorous comparative data are rare for seedlings. The goal of this study was to examine how light environment affects leaf life span, and how ontogenetic development during the first year may influence leaf fracture toughness, lamina density and stem density that are relevant for herbivory resistance, leaf life span and seedling survival. Methods Data from three experiments encompassing 104 neotropical woody species were combined. Leaf life span, lamina and vein fracture toughness, leaf and stem tissue density and seedling survival were quantified for the first-year seedlings at standardized ontogenetic stages in shade houses and common gardens established in gaps and shaded understorey in a moist tropical forest in Panama. Mortality of naturally recruited seedlings till 1 year later was quantified in 800 1-m2 plots from 1994 to 2011. Key Results Median leaf life span ranged widely among species, always greater in shade (ranging from 151 to >1790 d in the understorey and shade houses) than in gaps (115–867 d), but with strong correlation between gaps and shade. Leaf and stem tissue density increased with seedling age, whereas leaf fracture toughness showed only a weak increase. All these traits were positively correlated with leaf life span. Leaf life span and stem density were negatively correlated with seedling mortality in shade, while gap mortality showed no correlation with these traits. Conclusions The wide spectrum of leaf life span and associated functional traits reflects variation in shade tolerance of first-year seedlings among coexisting trees, shrubs and lianas in this neotropical forest. High leaf tissue density is important in enhancing leaf toughness, a known physical defence, and leaf life span. Both seedling leaf life span and stem density should be considered as key functional traits that contribute to seedling survival

  8. Phosphorus availability modulates the toxic effect of silver on aquatic fungi and leaf litter decomposition.

    PubMed

    Funck, J Arce; Clivot, H; Felten, V; Rousselle, P; Guérold, F; Danger, M

    2013-11-15

    The functioning of forested headwater streams is intimately linked to the decomposition of leaf litter by decomposers, mainly aquatic hyphomycetes, which enables the transfer of allochthonous carbon to higher trophic levels. Evaluation of this process is being increasingly used as an indicator of ecosystem health and ecological integrity. Yet, even though the individual impacts of contaminants and nutrient availability on decomposition have been well studied, the understanding of their combined effects remains limited. In the current study, we investigated whether the toxic effects of a reemerging contaminant, silver (Ag), on leaf litter decomposition could be partly overcome in situations where microorganisms were benefitting from high phosphorus (P) availability, the latter being a key chemical element that often limits detritus decomposition. We also investigated whether these interactive effects were mediated by changes in the structure of the aquatic hyphomycete community. To verify these hypotheses, leaf litter decomposition by a consortium of ten aquatic hyphomycete species was followed in a microcosm experiment combining five Ag contamination levels and three P concentrations. Indirect effects of Ag and P on the consumption of leaf litter by the detritivorous crustacean, Gammarus fossarum, were also evaluated. Ag significantly reduced decomposition but only at the highest concentration tested, independently of P level. By contrast, P and Ag interactively affected fungal biomass. Both P level and Ag concentrations shaped microbial communities without significantly affecting the overall species richness. Finally, the levels of P and Ag interacted significantly on G. fossarum feeding rates, high [Ag] reducing litter consumption and low P availability tending to intensify the feeding rate. Given the high level of contaminant needed to impair the decomposition process, it is unlikely that a direct effect of Ag on leaf litter decomposition could be observed in

  9. Psidium guajava and Piper betle Leaf Extracts Prolong Vase Life of Cut Carnation (Dianthus caryophyllus) Flowers

    PubMed Central

    Rahman, M. M.; Ahmad, S. H.; Lgu, K. S.

    2012-01-01

    The effect of leaf extracts of Psidium guajava and Piper betle on prolonging vase life of cut carnation flowers was studied. “Carola” and “Pallas Orange” carnation flowers, at bud stage, were pulsed 24 hours with a floral preservative. Then, flowers were placed in a vase solution containing sprite and a “germicide” (leaf extracts of P. guajava and P. betle, 8-HQC, or a copper coin). Flowers treated with 8-HQC, copper coin, and leaf extracts had longer vase life, larger flower diameter, and higher rate of water uptake compared to control (tap water). The leaf extracts of P. guajava and P. betle showed highest antibacterial and antifungal activities compared to the other treatments. Both showed similar effects on flower quality as the synthetic germicide, 8-HQC. Therefore, these extracts are likely natural germicides to prolong vase life of cut flowers. PMID:22619568

  10. Patterns of Leaf Biochemical and Structural Properties of Cerrado Life Forms: Implications for Remote Sensing

    PubMed Central

    Ball, Aaron; Sanchez-Azofeifa, Arturo; Portillo-Quintero, Carlos; Rivard, Benoit; Castro-Contreras, Saulo; Fernandes, Geraldo

    2015-01-01

    Aim The general goal of this study is to investigate and analyze patterns of ecophysiological leaf traits and spectral response among life forms (trees, shrubs and lianas) in the Cerrado ecosystem. In this study, we first tested whether life forms are discriminated through leaf level functional traits. We then explored the correlation between leaf-level plant functional traits and spectral reflectance. Location Serra do Cipo National Park, Minas Gerais, Brazil. Methods Six ecophysiological leaf traits were selected to best characterize differences between life forms in the woody plant community of the Cerrado. Results were compared to spectral vegetation indices to determine if plant groups provide means to separate leaf spectral responses. Results Values obtained from leaf traits were similar to results reported from other tropical dry sites. Trees and shrubs significantly differed from lianas in terms of the percentage of leaf water content and Specific Leaf Area. Spectral indices were insufficient to capture the differences of these key traits between groups, though indices were still adequately correlated to overall trait variation. Conclusion The importance of life forms as biochemical and structurally distinctive groups is a significant finding for future remote sensing studies of vegetation, especially in arid and semi-arid environments. The traits we found as indicative of these groups (SLA and water content) are good candidates for spectral characterization. Future studies need to use the full wavelength (400 nm–2500 nm) in order to capture the potential response of these traits. The ecological linkage to water balance and life strategies encourages these traits as starting points for modeling plant communities using hyperspectral remote sensing. PMID:25692675

  11. Leaf hydraulic vulnerability to drought is linked to site water availability across a broad range of species and climates

    PubMed Central

    Blackman, Chris J.; Gleason, Sean M.; Chang, Yvonne; Cook, Alicia M.; Laws, Claire; Westoby, Mark

    2014-01-01

    Background and Aims Vulnerability of the leaf hydraulic pathway to water-stress-induced dysfunction is a key component of drought tolerance in plants and may be important in defining species' climatic range. However, the generality of the association between leaf hydraulic vulnerability and climate across species and sites remains to be tested. Methods Leaf hydraulic vulnerability to drought (P50leaf, the water potential inducing 50 % loss in hydraulic function) was measured in a diverse group of 92 woody, mostly evergreen angiosperms from sites across a wide range of habitats. These new data together with some previously published were tested against key climate indices related to water availability. Differences in within-site variability in P50leaf between sites were also examined. Key Results Values of hydraulic vulnerability to drought in leaves decreased strongly (i.e. became more negative) with decreasing annual rainfall and increasing aridity across sites. The standard deviation in P50leaf values recorded within each site was positively correlated with increasing aridity. P50leaf was also a good indicator of the climatic envelope across each species' distributional range as well as their dry-end distributional limits within Australia, although this relationship was not consistently detectable within sites. Conclusions The findings indicate that species sorting processes have influenced distributional patterns of P50leaf across the rainfall spectrum, but alternative strategies for dealing with water deficit exist within sites. The strong link to aridity suggests leaf hydraulic vulnerability may influence plant distributions under future climates. PMID:25006181

  12. Several aspects of cultivating leaf greens in bioregenerative life support systems

    NASA Astrophysics Data System (ADS)

    Levinskikh, M. A.; Podolsky, I. G.; Sychev, V. N.

    Available results of theoretical and empirical studies of closed eco-systems lay the ground for the common opinion concerning desirability of incorporating higher plant cultivation equipment in the life support systems of closed habitats of varying purpose (space stations, Martian expedition, hyperbaric complexes in deep waters etc.) in order to add fresh greens to food rations, regenerate air and water, and to better the psychological climate. Design and functional features of this equipment and choice of plants are determined by the dimensions of habitat, power generation, length of self-sustained existence beyond Earth's biosphere and other factors. We are going to consider a particular case of fresh green biomass production for space crew nutrition with limited size and energy resources. The paper presents results of ground and space experimental investigations of a number of aspects of cultivating leaf plant species as applied to research and productive greenhouses. Goals of the investigations were to prepare for flight experiments in greenhouses LADA aboard ISS, and determination of specifications for future productive greenhouses for a Martian mission and its prototyping in ground-based simulations. The following objectives were pursued: - selection of the seeding surface shape and spatial configuration of productive and research greenhouses that can be proposed for the orbital station or a Martian vehicle comparison of productivity of leaf greens cultivated on different substrates; - determination of the maximal plant biomass yield and number of crops that can be gathered from root module without substrate change; - choice of leaf culture cultivars and species featured by very quick biomass buildup and pleasant taste qualities.

  13. Lotus leaf extract and L-carnitine influence different processes during the adipocyte life cycle

    PubMed Central

    2010-01-01

    by a decrease in the ADD1/SREBP-1c signal. Importantly, our results demonstrated that a combination of lotus leaf extract solution and L-carnitine reduced triglyceride accumulation to a greater extent compared to incubation with either substance alone. Conclusions Overall, our data demonstrate that a combination of lotus leaf extract and L-carnitine reduced triglyceride accumulation in human (pre)adipocytes by affecting different processes during the adipocyte life cycle. For this reason, this combination might represent a treatment option for obesity-related diseases. PMID:20687953

  14. Quantifying plant age and available water effects on soybean leaf conductance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In this study, we present data characterizing the effects of soil moisture levels on total leaf conductance for two distinct determinate soybean (Glycine max (L.) Merr.) genotypes and subsequently use these data to formulate and validate a model that characterizes total leaf conductance. Conductanc...

  15. Leaf Mass per Area (LMA) and Its Relationship with Leaf Structure and Anatomy in 34 Mediterranean Woody Species along a Water Availability Gradient.

    PubMed

    de la Riva, Enrique G; Olmo, Manuel; Poorter, Hendrik; Ubera, José Luis; Villar, Rafael

    2016-01-01

    Leaf mass per area (LMA) is a morphological trait widely used as a good indicator of plant functioning (i.e. photosynthetic and respiratory rates, chemical composition, resistance to herbivory, etc.). The LMA can be broken down into the leaf density (LD) and leaf volume to area ratio (LVA or thickness), which in turn are determined by anatomical tissues and chemical composition. The aim of this study is to understand the anatomical and chemical characteristics related to LMA variation in species growing in the field along a water availability gradient. We determined LMA and its components (LD, LVA and anatomical tissues) for 34 Mediterranean (20 evergreen and 14 deciduous) woody species. Variation in LMA was due to variation in both LD and LVA. For both deciduous and evergreen species LVA variation was strongly and positively related with mesophyll volume per area (VA or thickness), but for evergreen species positive relationships of LVA with the VA of epidermis, vascular plus sclerenchyma tissues and air spaces were found as well. The leaf carbon concentration was positively related with mesophyll VA in deciduous species, and with VA of vascular plus sclerenchymatic tissues in evergreens. Species occurring at the sites with lower water availability were generally characterised by a high LMA and LD. PMID:26867213

  16. Leaf Mass per Area (LMA) and Its Relationship with Leaf Structure and Anatomy in 34 Mediterranean Woody Species along a Water Availability Gradient

    PubMed Central

    de la Riva, Enrique G.; Olmo, Manuel; Poorter, Hendrik; Ubera, José Luis; Villar, Rafael

    2016-01-01

    Leaf mass per area (LMA) is a morphological trait widely used as a good indicator of plant functioning (i.e. photosynthetic and respiratory rates, chemical composition, resistance to herbivory, etc.). The LMA can be broken down into the leaf density (LD) and leaf volume to area ratio (LVA or thickness), which in turn are determined by anatomical tissues and chemical composition. The aim of this study is to understand the anatomical and chemical characteristics related to LMA variation in species growing in the field along a water availability gradient. We determined LMA and its components (LD, LVA and anatomical tissues) for 34 Mediterranean (20 evergreen and 14 deciduous) woody species. Variation in LMA was due to variation in both LD and LVA. For both deciduous and evergreen species LVA variation was strongly and positively related with mesophyll volume per area (VA or thickness), but for evergreen species positive relationships of LVA with the VA of epidermis, vascular plus sclerenchyma tissues and air spaces were found as well. The leaf carbon concentration was positively related with mesophyll VA in deciduous species, and with VA of vascular plus sclerenchymatic tissues in evergreens. Species occurring at the sites with lower water availability were generally characterised by a high LMA and LD. PMID:26867213

  17. Causes and consequences of variation in conifer leaf life-span

    SciTech Connect

    Reich, P.B.; Koike, T.; Gower, S.T.; Schoettle, A.W.

    1995-07-01

    Species with mutually supporting traits, such as high N{sub mass}, SLA, and A{sub mass}, and short leaf life-span, tend to inhabit either generally resource-rich environments or spatial and/or temporal microhabitats that are resource-rich in otherwise more limited habitats (e.g., {open_quotes}precipitation{close_quotes} ephemerals in warm deserts or spring ephemerals in the understory of temperate deciduous forests). In contrast, species with long leaf life-span often support foliage with low SLA, N{sub mass}, and A{sub mass}, and often grow in low-temperature limited, dry, and/or nutrient-poor environments. The contrast between evergreen and deciduous species, and the implications that emerge from such comparisons, can be considered a paradigm of modern ecological theory. However, based on the results of Reich et al. (1992) and Gower et al. (1993), coniferous species with foliage that persists for 9-10 years are likely to assimilate and allocate carbon and nutrients differently than other evergreen conifers that retain foliage for 2-3 years. Thus, attempts to contrast ecophysiological or ecosystem characteristics of evergreen versus deciduous life forms may be misleading, and pronounced differences among evergreen conifers may be ignored. Clearly, the deciduous-evergreen contrast, although useful in several ways, should be viewed from the broader perspective of a gradient in leaf life-span.

  18. A cost–benefit analysis of acclimation to low irradiance in tropical rainforest tree seedlings: leaf life span and payback time for leaf deployment

    PubMed Central

    Coste, Sabrina; Roggy, Jean-Christophe; Schimann, Heidy; Epron, Daniel; Dreyer, Erwin

    2011-01-01

    The maintenance in the long run of a positive carbon balance under very low irradiance is a prerequisite for survival of tree seedlings below the canopy or in small gaps in a tropical rainforest. To provide a quantitative basis for this assumption, experiments were carried out to determine whether construction cost (CC) and payback time for leaves and support structures, as well as leaf life span (i) differ among species and (ii) display an irradiance-elicited plasticity. Experiments were also conducted to determine whether leaf life span correlates to CC and payback time and is close to the optimal longevity derived from an optimization model. Saplings from 13 tropical tree species were grown under three levels of irradiance. Specific-CC was computed, as well as CC scaled to leaf area at the metamer level. Photosynthesis was recorded over the leaf life span. Payback time was derived from CC and a simple photosynthesis model. Specific-CC displayed only little interspecific variability and irradiance-elicited plasticity, in contrast to CC scaled to leaf area. Leaf life span ranged from 4 months to >26 months among species, and was longest in seedlings grown under lowest irradiance. It was always much longer than payback time, even under the lowest irradiance. Leaves were shed when their photosynthesis had reached very low values, in contrast to what was predicted by an optimality model. The species ranking for the different traits was stable across irradiance treatments. The two pioneer species always displayed the smallest CC, leaf life span, and payback time. All species displayed a similar large irradiance-elicited plasticity. PMID:21511904

  19. Modelling sugar diffusion across plant leaf cuticles: the effect of free water on substrate availability to phyllosphere bacteria.

    PubMed

    van der Wal, Annemieke; Leveau, Johan H J

    2011-03-01

    We present a continuous model for the diffusion of sugars across intact plant leaf cuticles. It is based on the flow of sugars from a source, representing the leaf apoplast, to a sink, in the shape of a hemispherical drop of water on the outside of the cuticle. Flow is a function of the difference between sugar concentrations C(Source) and C(Sink) , permeability P of the cuticle, volume V(Sink) of the water drop, as well as its contact angle α with the cuticle surface. Using a bacterial bioreporter for fructose, and a two-compartment experimental set-up consisting of isolated cuticles of walnut (Juglans regia) carrying water droplets while floating on solutions with increasing concentrations of fructose, we determined a value of 1 × 10⁻⁶ m h⁻¹ for P. Using this value, we explored different scenarios for the leaching of sugars across plant leaf cuticles to reveal in quantitative terms how diffusion takes longer when V(Sink) increases, P decreases or α increases. Bacterial growth was modelled as a function of changes in P, α and V(Sink) and was consistent with observations or suggestions from the literature in relation to the availability of free water on leaves. These results are discussed in the light of bacteria as ecosystem engineers, i.e. with the ability to modify the plant leaf surface environment in favour of their own survival, e.g. by increasing cuticle leakage or leaf wetness. Our model represents a first step towards a more comprehensive model which will enhance our quantitative understanding of the factors that play a role in nutrient availability to bacterial colonizers of the phyllosphere, or plant leaf surface. PMID:21091864

  20. Leaf and life history traits predict plant growth in a green roof ecosystem.

    PubMed

    Lundholm, Jeremy; Heim, Amy; Tran, Stephanie; Smith, Tyler

    2014-01-01

    Green roof ecosystems are constructed to provide services such as stormwater retention and urban temperature reductions. Green roofs with shallow growing media represent stressful conditions for plant survival, thus plants that survive and grow are important for maximizing economic and ecological benefits. While field trials are essential for selecting appropriate green roof plants, we wanted to determine whether plant leaf traits could predict changes in abundance (growth) to provide a more general framework for plant selection. We quantified leaf traits and derived life-history traits (Grime's C-S-R strategies) for 13 species used in a four-year green roof experiment involving five plant life forms. Changes in canopy density in monocultures and mixtures containing one to five life forms were determined and related to plant traits using multiple regression. We expected traits related to stress-tolerance would characterize the species that best grew in this relatively harsh setting. While all species survived to the end of the experiment, canopy species diversity in mixture treatments was usually much lower than originally planted. Most species grew slower in mixture compared to monoculture, suggesting that interspecific competition reduced canopy diversity. Species dominant in mixture treatments tended to be fast-growing ruderals and included both native and non-native species. Specific leaf area was a consistently strong predictor of final biomass and the change in abundance in both monoculture and mixture treatments. Some species in contrasting life-form groups showed compensatory dynamics, suggesting that life-form mixtures can maximize resilience of cover and biomass in the face of environmental fluctuations. This study confirms that plant traits can be used to predict growth performance in green roof ecosystems. While rapid canopy growth is desirable for green roofs, maintenance of species diversity may require engineering of conditions that favor less

  1. Leaf and Life History Traits Predict Plant Growth in a Green Roof Ecosystem

    PubMed Central

    Lundholm, Jeremy; Heim, Amy; Tran, Stephanie; Smith, Tyler

    2014-01-01

    Green roof ecosystems are constructed to provide services such as stormwater retention and urban temperature reductions. Green roofs with shallow growing media represent stressful conditions for plant survival, thus plants that survive and grow are important for maximizing economic and ecological benefits. While field trials are essential for selecting appropriate green roof plants, we wanted to determine whether plant leaf traits could predict changes in abundance (growth) to provide a more general framework for plant selection. We quantified leaf traits and derived life-history traits (Grime’s C-S-R strategies) for 13 species used in a four-year green roof experiment involving five plant life forms. Changes in canopy density in monocultures and mixtures containing one to five life forms were determined and related to plant traits using multiple regression. We expected traits related to stress-tolerance would characterize the species that best grew in this relatively harsh setting. While all species survived to the end of the experiment, canopy species diversity in mixture treatments was usually much lower than originally planted. Most species grew slower in mixture compared to monoculture, suggesting that interspecific competition reduced canopy diversity. Species dominant in mixture treatments tended to be fast-growing ruderals and included both native and non-native species. Specific leaf area was a consistently strong predictor of final biomass and the change in abundance in both monoculture and mixture treatments. Some species in contrasting life-form groups showed compensatory dynamics, suggesting that life-form mixtures can maximize resilience of cover and biomass in the face of environmental fluctuations. This study confirms that plant traits can be used to predict growth performance in green roof ecosystems. While rapid canopy growth is desirable for green roofs, maintenance of species diversity may require engineering of conditions that favor less

  2. "Life in the Universe" Final Event Video Now Available

    NASA Astrophysics Data System (ADS)

    2002-02-01

    ESO Video Clip 01/02 is issued on the web in conjunction with the release of a 20-min documentary video from the Final Event of the "Life in the Universe" programme. This unique event took place in November 2001 at CERN in Geneva, as part of the 2001 European Science and Technology Week, an initiative by the European Commission to raise the public awareness of science in Europe. The "Life in the Universe" programme comprised competitions in 23 European countries to identify the best projects from school students. The projects could be scientific or a piece of art, a theatrical performance, poetry or even a musical performance. The only restriction was that the final work must be based on scientific evidence. Winning teams from each country were invited to a "Final Event" at CERN on 8-11 November, 2001 to present their projects to a panel of International Experts during a special three-day event devoted to understanding the possibility of other life forms existing in our Universe. This Final Event also included a spectacular 90-min webcast from CERN with the highlights of the programme. The video describes the Final Event and the enthusiastic atmosphere when more than 200 young students and teachers from all over Europe met with some of the world's leading scientific experts of the field. The present video clip, with excerpts from the film, is available in four versions: two MPEG files and two streamer-versions of different sizes; the latter require RealPlayer software. Video Clip 01/02 may be freely reproduced. The 20-min video is available on request from ESO, for viewing in VHS and, for broadcasters, in Betacam-SP format. Please contact the ESO EPR Department for more details. Life in the Universe was jointly organised by the European Organisation for Nuclear Research (CERN) , the European Space Agency (ESA) and the European Southern Observatory (ESO) , in co-operation with the European Association for Astronomy Education (EAAE). Other research organisations were

  3. Space Transportation System Availability Relationships to Life Cycle Cost

    NASA Technical Reports Server (NTRS)

    Rhodes, Russel E.; Donahue, Benjamin B.; Chen, Timothy T.

    2009-01-01

    Future space transportation architectures and designs must be affordable. Consequently, their Life Cycle Cost (LCC) must be controlled. For the LCC to be controlled, it is necessary to identify all the requirements and elements of the architecture at the beginning of the concept phase. Controlling LCC requires the establishment of the major operational cost drivers. Two of these major cost drivers are reliability and maintainability, in other words, the system's availability (responsiveness). Potential reasons that may drive the inherent availability requirement are the need to control the number of unique parts and the spare parts required to support the transportation system's operation. For more typical space transportation systems used to place satellites in space, the productivity of the system will drive the launch cost. This system productivity is the resultant output of the system availability. Availability is equal to the mean uptime divided by the sum of the mean uptime plus the mean downtime. Since many operational factors cannot be projected early in the definition phase, the focus will be on inherent availability which is equal to the mean time between a failure (MTBF) divided by the MTBF plus the mean time to repair (MTTR) the system. The MTBF is a function of reliability or the expected frequency of failures. When the system experiences failures the result is added operational flow time, parts consumption, and increased labor with an impact to responsiveness resulting in increased LCC. The other function of availability is the MTTR, or maintainability. In other words, how accessible is the failed hardware that requires replacement and what operational functions are required before and after change-out to make the system operable. This paper will describe how the MTTR can be equated to additional labor, additional operational flow time, and additional structural access capability, all of which drive up the LCC. A methodology will be presented that

  4. Short-Term Effect of Nutrient Availability and Rainfall Distribution on Biomass Production and Leaf Nutrient Content of Savanna Tree Species

    PubMed Central

    Barbosa, Eduardo R. M.; Tomlinson, Kyle W.; Carvalheiro, Luísa G.; Kirkman, Kevin; de Bie, Steven; Prins, Herbert H. T.; van Langevelde, Frank

    2014-01-01

    Changes in land use may lead to increased soil nutrient levels in many ecosystems (e.g. due to intensification of agricultural fertilizer use). Plant species differ widely in their response to differences in soil nutrients, and for savannas it is uncertain how this nutrient enrichment will affect plant community dynamics. We set up a large controlled short-term experiment in a semi-arid savanna to test how water supply (even water supply vs. natural rainfall) and nutrient availability (no fertilisation vs. fertilisation) affects seedlings’ above-ground biomass production and leaf-nutrient concentrations (N, P and K) of broad-leafed and fine-leafed tree species. Contrary to expectations, neither changes in water supply nor changes in soil nutrient level affected biomass production of the studied species. By contrast, leaf-nutrient concentration did change significantly. Under regular water supply, soil nutrient addition increased the leaf phosphorus concentration of both fine-leafed and broad-leafed species. However, under uneven water supply, leaf nitrogen and phosphorus concentration declined with soil nutrient supply, this effect being more accentuated in broad-leafed species. Leaf potassium concentration of broad-leafed species was lower when growing under constant water supply, especially when no NPK fertilizer was applied. We found that changes in environmental factors can affect leaf quality, indicating a potential interactive effect between land-use changes and environmental changes on savanna vegetation: under more uneven rainfall patterns within the growing season, leaf quality of tree seedlings for a number of species can change as a response to changes in nutrient levels, even if overall plant biomass does not change. Such changes might affect herbivore pressure on trees and thus savanna plant community dynamics. Although longer term experiments would be essential to test such potential effects of eutrophication via changes in leaf nutrient

  5. Short-term effect of nutrient availability and rainfall distribution on biomass production and leaf nutrient content of savanna tree species.

    PubMed

    Barbosa, Eduardo R M; Tomlinson, Kyle W; Carvalheiro, Luísa G; Kirkman, Kevin; de Bie, Steven; Prins, Herbert H T; van Langevelde, Frank

    2014-01-01

    Changes in land use may lead to increased soil nutrient levels in many ecosystems (e.g. due to intensification of agricultural fertilizer use). Plant species differ widely in their response to differences in soil nutrients, and for savannas it is uncertain how this nutrient enrichment will affect plant community dynamics. We set up a large controlled short-term experiment in a semi-arid savanna to test how water supply (even water supply vs. natural rainfall) and nutrient availability (no fertilisation vs. fertilisation) affects seedlings' above-ground biomass production and leaf-nutrient concentrations (N, P and K) of broad-leafed and fine-leafed tree species. Contrary to expectations, neither changes in water supply nor changes in soil nutrient level affected biomass production of the studied species. By contrast, leaf-nutrient concentration did change significantly. Under regular water supply, soil nutrient addition increased the leaf phosphorus concentration of both fine-leafed and broad-leafed species. However, under uneven water supply, leaf nitrogen and phosphorus concentration declined with soil nutrient supply, this effect being more accentuated in broad-leafed species. Leaf potassium concentration of broad-leafed species was lower when growing under constant water supply, especially when no NPK fertilizer was applied. We found that changes in environmental factors can affect leaf quality, indicating a potential interactive effect between land-use changes and environmental changes on savanna vegetation: under more uneven rainfall patterns within the growing season, leaf quality of tree seedlings for a number of species can change as a response to changes in nutrient levels, even if overall plant biomass does not change. Such changes might affect herbivore pressure on trees and thus savanna plant community dynamics. Although longer term experiments would be essential to test such potential effects of eutrophication via changes in leaf nutrient concentration

  6. Biomass, Leaf Area, and Resource Availability of Kudzu Dominated Plant Communities Following Herbicide Treatment

    SciTech Connect

    L.T. Rader

    2001-10-01

    Kudzu is an exotic vine that threatens the forests of the southern U.S. Five herbicides were tested with regard to their efficacy in controlling kudzu, community recover was monitored, and interactions with planted pines were studied. The sites selected were old farm sites dominated by kudzu.These were burned following herbicide treatment. The herbicides included triclopyr, clopyralid, metsulfuron, tebuthiuron, and picloram plus 2,4-D. Pine seedlings were planted the following year. Regression equations were developed for predicting biomass and leaf area. Four distinct plant communities resulted from the treatments. The untreated check continued to be kudzu dominated. Blackberry dominated the clopyradid treatment. Metsulfron, trychlopyr and picloram treated sites resulted in herbaceous dominated communities. The tebuthiuron treatment maintained all vegetation low.

  7. Leaf and ecosystem response to soil water availability in mountain grasslands

    PubMed Central

    Brilli, Federico; Hörtnagl, Lukas; Hammerle, Albin; Haslwanter, Alois; Hansel, Armin; Loreto, Francesco; Wohlfahrt, Georg

    2014-01-01

    Climate change is expected to affect the Alps by increasing the frequency and intensity of summer drought events with negative impacts on ecosystem water resources. The response of CO2 and H2O exchange of a mountain grassland to natural fluctuations of soil water content was evaluated during 2001-2009. In addition, the physiological performance of individual mountain forb and graminoid plant species under progressive soil water shortage was explored in a laboratory drought experiment. During the 9-year study period the natural occurrence of moderately to extremely dry periods did not lead to substantial reductions in net ecosystem CO2 exchange and evapotranspiration. Laboratory drought experiments confirmed that all the surveyed grassland plant species were insensitive to progressive soil drying until very low soil water contents (<0.01 m3 m−3) were reached after several days of drought. In field conditions, such a low threshold was never reached. Re-watering after a short-term drought event (5±1 days) resulted in a fast and complete recovery of the leaf CO2 and H2O gas exchange of the investigated plant species. We conclude that the present-day frequency and intensity of dry periods does not substantially affect the functioning of the investigated grassland ecosystem. During dry periods the observed “water spending” strategy employed by the investigated mountain grassland species is expected to provide a cooling feedback on climate warming, but may have negative consequences for down-stream water users. PMID:24465071

  8. Stirling engine—available tools for long-life assessment

    NASA Astrophysics Data System (ADS)

    Halford, Gary R.; Bartolotta, Paul A.

    1991-01-01

    A review is presented of the durability approaches applicable to long-time life assessment of Stirling engine hot-section components. The crucial elements are: (i) experimental techniques for generating long-time materials property data (both monotonic and cyclic flow and failure properties), (ii) analytic representations of slow strain rate material stress-strain response characteristics (monotonic and cyclic constitutive relations) at high temperatures and low stresses and strains, (iii) analytic creep-fatigue-environmental interaction life prediction methods applicable to long lifetimes at high temperatures and small stresses and strains, and (iv) experimental verification of life predictions. Long-lifetime design criteria for materials of interest are woefully lacking. Designing against failures due to creep, creep-rupture, fatigue, environmental attack, and creep-fatigue-environmental interaction will require considerable extrapolation. Viscoplastic constitutive models and time-temperature parameters will have to be calibrated for the hot-section materials of interest. Analysis combined with limited verification testing in a short-time regime will be required to build confidence in long-term durability models. A strong need exists for improved long-lifetime durability models.

  9. Stirling engine: Available tools for long-life assessment

    NASA Technical Reports Server (NTRS)

    Halford, Gary R.; Bartolotta, Paul A.

    1991-01-01

    A review is presented for the durability approaches applicable to long-time life assessment of Stirling engine hot-section components. The crucial elements are experimental techniques for generating long-time materials property data (both monotonic and cyclic flow and failure properties); analytic representations of slow strain rate material stress-strain response characteristics (monotonic and cyclic constitutive relations) at high temperatures and low stresses and strains; analytic creep-fatigue-environmental interaction life prediction methods applicable to long lifetimes at high temperatures and small stresses and strains; and experimental verification of life predictions. Long-lifetime design criteria for materials of interest are woefully lacking. Designing against failures due to creep, creep-rupture, fatigue, environmental attack, and creep-fatigue-environmental interaction will require considerable extrapolation. Viscoplastic constitutive models and time-temperature parameters will have to be calibrated for the hot-section materials of interest. Analysis combined with limited verification testing in a short-time regime will be required to build confidence in long-lifetime durability models.

  10. Life history and assessment of grapevine phylloxera leaf galling incidence on Vitis species in Uruguay.

    PubMed

    Vidart, María Valeria; Mujica, María Valentina; Bao, Leticia; Duarte, Felicia; Bentancourt, Carlos María; Franco, Jorge; Scatoni, Iris Beatriz

    2013-12-01

    Grapevine phylloxera, Daktulosphaira vitifoliae (Fitch) (Hemiptera: Phylloxeridae) is a worldwide pest of Vitis species. It has forms that feed on leaves and roots. Root forms predominate on Vitis vinifera (L.) cultivars, while leaf forms predominate on Vitis species from its native American range. Recently, high densities of D. vitifoliae infestations in leaves of V. vinifera in Brazil, Peru, and Uruguay have been reported. The aims of this study were to determine the seasonal development of grape phylloxera, quantify infestation levels on V. vinifera leaves, and compare them with infestation levels on leaves of a rootstock of American origin. Studies were conducted in two vineyards in Uruguay from 2004-2007. Terminal shoots of 3309 C and Cabernet Sauvignon, Chardonnay, Tannat, Viognier, grafted onto resistant rootstock, were sampled weekly and leaves examined for gall presence and insect life stage. First galls were detected in early October; eggs began to appear within two weeks. Two oviposition peaks occurred by the end of December, and they coincided with bursts of shoot growth. On 3309C rootstock, oviposition peaks were more frequent than on the European cultivars. Based on thermal accumulation, D. vitifoliae could complete eight generations a year in Uruguay. Rootstock 3309C suffered the greatest damage but in some cases was similar to the European cultivars. Damage to Chardonnay, Cabernet Sauvignon and Viognier were also high. There were no galls on Tannat. The 2005-2006 season was characterized by low infestation rates caused by a prolonged drought that affected vegetative growth. There were also differences between vineyards, where the vigorous plants suffering more damage. Leaf galling phylloxera incidence and damage were mainly associated to the cultivar but plant vigor and environmental factors also contributed to increase the incidence. PMID:23667822

  11. Relationship between leaf life-span and photosynthetic activity of Quercus ilex in polluted urban areas (Rome).

    PubMed

    Gratani, L; Crescente, M F; Petruzzi, M

    2000-10-01

    Anatomical, morphological and physiological leaf traits of Quercus ilex in response to different traffic levels (high traffic level, type A sites; average traffic level, type B sites; control sites, type C sites) were analysed in Rome. Superficial leaf deposits were analysed comparing unwashed and washed leaf samples. Washing lowered Pb 61% in A, 54% in B and 27% in C. Sr, Fe, Cu, Zn and Al showed the same trend as Pb. The higher photosynthetic activity of 1-year-old leaves (Pn=7.0+/-2.9 micromol m(-2 )s(-1), average value) in A sites with respect to B sites (6.7+/-2.4 micromol m(-2 )s(-1)) and C sites (6.7+/-1.8 micromol m(-2 )s(-1)) seems to be related to higher stomatal conductance (g(s)=0.13+/-0.06 mol m(-2 )s(-1)), higher total chlorophyll content (Chl=1.57 mg g(-1)) and higher leaf thickness (L(T)=218.9 microm), particularly palisade parenchyma thickness (109.4 microm). Q. ilex showed, on average, 95% of 1-year-old leaves and rarely 2-year-old leaves in A and B sites; 77% 1-year leaves, 20% previous-year leaves and sporadic 3-year leaves in C sites. The enhanced leaf senescence in A sites is compensated by a stimulated shoot production (18% higher with respect to C sites); 25% increased specific leaf area seems to be compensatory growth occurring in order to increase the size of the assimilatory area. The inverse trend of leaf life-span and Pn seems to be Q. ilex' adaptive strategy in polluted areas. PMID:15092853

  12. Leaf hydraulic vulnerability to drought is linked to site water availability across a broad range of species and climates

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Background and Aims: Vulnerability of the leaf hydraulic pathway to water-stress-induced dysfunction is a key component of drought tolerance in plants and may be important in defining species’ climatic range. However, the generality of the association between leaf hydraulic vulnerability and climate...

  13. Within-twig leaf distribution patterns differ among plant life-forms in a subtropical Chinese forest.

    PubMed

    Meng, Fengqun; Cao, Rui; Yang, Dongmei; Niklas, Karl J; Sun, Shucun

    2013-07-01

    Amax) had more even leaf distribution patterns than evergreen species (which had low LCP, LSP and Amax); shade-adapted evergreen species had more even leaf distribution patterns than sun-adapted evergreen species. We propose that the leaf distribution pattern (i.e., 'evenness' CV, which is an easily measured functional trait) can be used to distinguish among life-forms in communities similar to the one examined in this study. PMID:23933830

  14. Canopy leaf area of a mature evergreen Eucalyptus woodland does not respond to elevated atmospheric [CO2 ] but tracks water availability.

    PubMed

    Duursma, Remko A; Gimeno, Teresa E; Boer, Matthias M; Crous, Kristine Y; Tjoelker, Mark G; Ellsworth, David S

    2016-04-01

    Canopy leaf area, quantified by the leaf area index (L), is a crucial driver of forest productivity, water use and energy balance. Because L responds to environmental drivers, it can represent an important feedback to climate change, but its responses to rising atmospheric [CO2 ] and water availability of forests have been poorly quantified. We studied canopy leaf area dynamics for 28 months in a native evergreen Eucalyptus woodland exposed to free-air CO2 enrichment (the EucFACE experiment), in a subtropical climate where water limitation is common. We hypothesized that, because of expected stimulation of productivity and water-use efficiency, L should increase with elevated [CO2 ]. We estimated L from diffuse canopy transmittance, and measured monthly leaf litter production. Contrary to expectation, L did not respond to elevated [CO2 ]. We found that L varied between 1.10 and 2.20 across the study period. The dynamics of L showed a quick increase after heavy rainfall and a steady decrease during periods of low rainfall. Leaf litter production was correlated to changes in L, both during periods of decreasing L (when no leaf growth occurred) and during periods of increasing L (active shedding of old foliage when new leaf growth occurred). Leaf lifespan, estimated from mean L and total annual litter production, was up to 2 months longer under elevated [CO2 ] (1.18 vs. 1.01 years; P = 0.05). Our main finding that L was not responsive to elevated CO2 is consistent with other forest FACE studies, but contrasts with the positive response of L commonly predicted by many ecosystem models. PMID:26546378

  15. Morphological and moisture availability controls of the leaf area-to-sapwood area ratio: analysis of measurements on Australian trees.

    PubMed

    Togashi, Henrique Furstenau; Prentice, Iain Colin; Evans, Bradley John; Forrester, David Ian; Drake, Paul; Feikema, Paul; Brooksbank, Kim; Eamus, Derek; Taylor, Daniel

    2015-03-01

    The leaf area-to-sapwood area ratio (LA:SA) is a key plant trait that links photosynthesis to transpiration. The pipe model theory states that the sapwood cross-sectional area of a stem or branch at any point should scale isometrically with the area of leaves distal to that point. Optimization theory further suggests that LA:SA should decrease toward drier climates. Although acclimation of LA:SA to climate has been reported within species, much less is known about the scaling of this trait with climate among species. We compiled LA:SA measurements from 184 species of Australian evergreen angiosperm trees. The pipe model was broadly confirmed, based on measurements on branches and trunks of trees from one to 27 years old. Despite considerable scatter in LA:SA among species, quantile regression showed strong (0.2 < R1 < 0.65) positive relationships between two climatic moisture indices and the lowermost (5%) and uppermost (5-15%) quantiles of log LA:SA, suggesting that moisture availability constrains the envelope of minimum and maximum values of LA:SA typical for any given climate. Interspecific differences in plant hydraulic conductivity are probably responsible for the large scatter of values in the mid-quantile range and may be an important determinant of tree morphology. PMID:25859331

  16. Moisture availability constraints on the leaf area to sapwood area ratio: analysis of measurements on Australian evergreen angiosperm trees

    NASA Astrophysics Data System (ADS)

    Togashi, Henrique; Prentice, Colin; Evans, Bradley; Forrester, David; Drake, Paul; Feikema, Paul; Brooksbank, Kim; Eamus, Derek; Taylor, Daniel

    2014-05-01

    The leaf area to sapwood area ratio (LA:SA) is a key plant trait that links photosynthesis to transpiration. Pipe model theory states that the sapwood cross-sectional area of a stem or branch at any point should scale isometrically with the area of leaves distal to that point. Optimization theory further suggests that LA:SA should decrease towards drier climates. Although acclimation of LA:SA to climate has been reported within species, much less is known about the scaling of this trait with climate among species. We compiled LA:SA measurements from 184 species of Australian evergreen angiosperm trees. The pipe model was broadly confirmed, based on measurements on branches and trunks of trees from one to 27 years old. We found considerable scatter in LA:SA among species. However quantile regression showed strong (0.2availability constrains the envelope of minimum and maximum values of LA:SA typical for any given climate. Interspecific differences in plant hydraulic conductivity are probably responsible for the large scatter of values in the mid quantile-range, and may be an important determinant of tree morphology.

  17. Morphological and moisture availability controls of the leaf area-to-sapwood area ratio: analysis of measurements on Australian trees

    PubMed Central

    Togashi, Henrique Furstenau; Prentice, Iain Colin; Evans, Bradley John; Forrester, David Ian; Drake, Paul; Feikema, Paul; Brooksbank, Kim; Eamus, Derek; Taylor, Daniel

    2015-01-01

    The leaf area-to-sapwood area ratio (LA:SA) is a key plant trait that links photosynthesis to transpiration. The pipe model theory states that the sapwood cross-sectional area of a stem or branch at any point should scale isometrically with the area of leaves distal to that point. Optimization theory further suggests that LA:SA should decrease toward drier climates. Although acclimation of LA:SA to climate has been reported within species, much less is known about the scaling of this trait with climate among species. We compiled LA:SA measurements from 184 species of Australian evergreen angiosperm trees. The pipe model was broadly confirmed, based on measurements on branches and trunks of trees from one to 27 years old. Despite considerable scatter in LA:SA among species, quantile regression showed strong (0.2 < R1 < 0.65) positive relationships between two climatic moisture indices and the lowermost (5%) and uppermost (5–15%) quantiles of log LA:SA, suggesting that moisture availability constrains the envelope of minimum and maximum values of LA:SA typical for any given climate. Interspecific differences in plant hydraulic conductivity are probably responsible for the large scatter of values in the mid-quantile range and may be an important determinant of tree morphology. PMID:25859331

  18. Effect of water availability on leaf water isotopic enrichment in beech seedlings shows limitations of current fractionation models.

    PubMed

    Ferrio, Juan Pedro; Cuntz, Matthias; Offermann, Christine; Siegwolf, Rolf; Saurer, Matthias; Gessler, Arthur

    2009-10-01

    Current models of leaf water enrichment predict that the differences between isotopic enrichment of water at the site of evaporation (Delta(e)) and mean lamina leaf water enrichment (Delta(L)) depend on transpiration rates (E), modulated by the scaled effective length (L) of water isotope movement in the leaf. However, variations in leaf parameters in response to changing environmental conditions might cause changes in the water path and thus L. We measured the diel course of Delta(L) for (18)O and (2)H in beech seedlings under well-watered and water-limited conditions. We applied evaporative enrichment models of increasing complexity to predict Delta(e) and Delta(L), and estimated L from model fits. Water-limited plants showed moderate drought stress, with lower stomatal conductance, E and stem water potential than the control. Despite having double E, the divergence between Delta(e) and Delta(L) was lower in well-watered than in water-limited plants, and thus, L should have changed to counteract differences in E. Indeed, L was about threefold higher in water-limited plants, regardless of the models used. We conclude that L changes with plant water status far beyond the variations explained by water content and other measured variables, thus limiting the use of current evaporative models under changing environmental conditions. PMID:19453484

  19. Senescence-inducible expression of isopentenyl transferase extends leaf life, increases drought stress resistance and alters cytokinin metabolism in cassava.

    PubMed

    Zhang, Peng; Wang, Wen-Quan; Zhang, Gen-Liang; Kaminek, Miroslav; Dobrev, Petre; Xu, Jia; Gruissem, Wilhelm

    2010-07-01

    Cassava (Manihot esculenta Crantz) sheds its leaves during growth, especially within the tropical dry season. With the production of SAG12-IPT transgenic cassava we want to test the level of leaf retention and altered cytokinin metabolism of transgenic plants via the autoregulatory senescence inhibition system. After confirmation of transgene expression by molecular analysis and phenotype examination in greenhouse plants, two transgenic plant lines, 529-28 and 529-48, were chosen for further investigation. Detached mature leaves of 529-28 plants retained high levels of chlorophyll compared with wild-type leaves after dark-induced senescence treatment. Line 529-28 showed significant drought tolerance as indicated by stay-green capacity after drought stress treatment. Field experiments proved that leaf senescence syndrome was significantly delayed in 529-28 plants in comparison with wild-type and 529-48 plants. Physiological and agronomical characterizations of these plants also revealed that the induced expression of IPT had effects on photosynthesis, sugar allocation and nitrogen partitioning. Importantly, the 529-28 plants accumulated a high level of trans-zeatin-type cytokinins particularly of corresponding storage O-glucosides to maintain cytokinin homeostasis. Our study proves the feasibility of prolonging the leaf life of woody cassava and also sheds light on the control of cytokinin homeostasis in cassava leaves. PMID:20590995

  20. Leaf physiology and biomass allocation of backcross hybrid American chestnut (Castanea dentata) seedlings in response to light and water availability.

    PubMed

    Brown, Caleb E; Mickelbart, Michael V; Jacobs, Douglass F

    2014-12-01

    Partial canopy cover promotes regeneration of many temperate forest trees, but the consequences of shading on seedling drought resistance are unclear. Reintroduction of blight-resistant American chestnut (Castanea dentata (Marsh.) Borkh.) into eastern North American forests will often occur on water-limited sites and under partial canopy cover. We measured leaf pre-dawn water potential (Ψpd), leaf gas exchange, and growth and biomass allocation of backcross hybrid American chestnut seedlings from three orchard sources grown under different light intensities (76, 26 and 8% full photosynthetically active radiation (PAR)) and subjected to well-watered or mid-season water-stressed conditions. Seedlings in the water-stress treatment were returned to well-watered conditions after wilting to examine recovery. Seedlings growing under medium- and high-light conditions wilted at lower leaf Ψpd than low-light seedlings. Recovery of net photosynthesis (Anet) and stomatal conductance (gs) was greater in low and medium light than in high light. Seed source did not affect the response to water stress or light level in most cases. Between 26 and 8% full PAR, light became limiting to the extent that the effects of water stress had no impact on some growth and morphological traits. We conclude that positive and negative aspects of shading on seedling drought tolerance and recovery are not mutually exclusive. Partial shade may help American chestnut tolerate drought during early establishment through effects on physiological conditioning. PMID:25428828

  1. Carbon dynamics in aboveground biomass of co-dominant plant species: related rather to leaf life span than to species

    NASA Astrophysics Data System (ADS)

    Ostler, Ulrike; Schleip, Inga; Lattanzi, Fernando A.; Schnyder, Hans

    2016-04-01

    This study investigates the role of individual organisms in whole ecosystem carbon (C) fluxes. It is currently unknown if different plant community members share the same or different kinetics of C pools in aboveground biomass, thereby adding (or not) variability to the first steps in ecosystem C cycling. We assessed the residence times in metabolic and non-metabolic (or structural) C pools and the allocation pattern of assimilated C in aboveground plant parts of four co-existing, co-dominant species from different functional groups in a temperate grassland community. For this purpose continuous, 14-16 day long 13CO2/12CO2-labeling experiments were performed in Sept. 2006, May 2007 and Sept. 2007, and the tracer kinetics were analysed with compartmental modeling. In all experimental periods, the species shared vastly similar residence times in metabolic C (5-8 d). In contrast, the residence times in non-metabolic C ranged from 20 to 58 d (except one outlier) and the fraction of fixed C allocated to the non-metabolic pool from 7 to 45%. These variations in non-metabolic C kinetics were not systematically associated with species or experimental periods, but exhibited close relationships with (independent estimates of) leaf life span, particularly in the grasses. This adds new meaning to leaf life span as a functional trait in the leaf and plant economics spectrum and its implication for C cycle studies in grassland and also forest systems. As the four co-dominant species accounted for ~80% of total community shoot biomass, we should also expect that the observed similarities in pool kinetics and allocation will scale up to similar relationships at the community level.

  2. Changes in life history parameters of corn leaf aphid, Rhopalosiphum maidus (Homoptera: Aphididae), under four different elevated temperature and CO2 combinations

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Biological characteristics of corn leaf aphid, Rhopalosiphum maidis (Fitch), on barley, Hordeum vulgare L., were examined for two generations under four different elevated temperature and CO2 combinations. The developmental duration for each life stage was significantly reduced under the elevated te...

  3. Optimization of controlled environments for hydroponic production of leaf lettuce for human life support in CELSS

    NASA Technical Reports Server (NTRS)

    Mitchell, C. A.; Knight, S. L.; Ford, T. L.

    1986-01-01

    A research project in the food production group of the Closed Ecological Life Support System (CELSS) program sought to define optimum conditions for photosynthetic productivity of a higher plant food crop. The effects of radiation and various atmospheric compositions were studied.

  4. Life in leaf litter: novel insights into community dynamics of bacteria and fungi during litter decomposition.

    PubMed

    Purahong, Witoon; Wubet, Tesfaye; Lentendu, Guillaume; Schloter, Michael; Pecyna, Marek J; Kapturska, Danuta; Hofrichter, Martin; Krüger, Dirk; Buscot, François

    2016-08-01

    Microorganisms play a crucial role in the biological decomposition of plant litter in terrestrial ecosystems. Due to the permanently changing litter quality during decomposition, studies of both fungi and bacteria at a fine taxonomic resolution are required during the whole process. Here we investigated microbial community succession in decomposing leaf litter of temperate beech forest using pyrotag sequencing of the bacterial 16S and the fungal internal transcribed spacer (ITS) rRNA genes. Our results reveal that both communities underwent rapid changes. Proteobacteria, Actinobacteria and Bacteroidetes dominated over the entire study period, but their taxonomic composition and abundances changed markedly among sampling dates. The fungal community also changed dynamically as decomposition progressed, with ascomycete fungi being increasingly replaced by basidiomycetes. We found a consistent and highly significant correlation between bacterial richness and fungal richness (R = 0.76, P < 0.001) and community structure (RM antel  = 0.85, P < 0.001), providing evidence of coupled dynamics in the fungal and bacterial communities. A network analysis highlighted nonrandom co-occurrences among bacterial and fungal taxa as well as a shift in the cross-kingdom co-occurrence pattern of their communities from the early to the later stages of decomposition. During this process, macronutrients, micronutrients, C:N ratio and pH were significantly correlated with the fungal and bacterial communities, while bacterial richness positively correlated with three hydrolytic enzymes important for C, N and P acquisition. Overall, we provide evidence that the complex litter decay is the result of a dynamic cross-kingdom functional succession. PMID:27357176

  5. Current Quality-of-Life Tools Available for Use in Contact Dermatitis.

    PubMed

    Swietlik, Jacquelyn; Reeder, Margo

    2016-01-01

    Contact dermatitis is a common dermatologic condition that can cause significant impairment in patients' overall quality of life (QoL). This impact is separate and potentially more clinically relevant than one's disease "severity" in contact dermatitis and should be consistently addressed by dermatologists. Despite this, QoL tools specific to contact dermatitis are lacking, and there is little consistency in the literature regarding the tool used to evaluate clinical response to therapies. Measurements currently available to evaluate disease-related QoL in contact dermatitis fit into 1 of the following 3 general types: generic health-related QoL measures, dermatology-related QoL measures, or specific dermatologic disease-related QoL measures. This article reviews the strengths and weaknesses of existing QoL tools used in contact dermatitis including: Short Form Survey 36, Dermatology Life Quality Index, Skindex-29, Skindex-16, Dermatology-Specific Quality of Life, and Fragrance Quality of Life Index. PMID:27427819

  6. Mean residence time of leaf number, area, mass, and nitrogen in canopy photosynthesis.

    PubMed

    Hirose, Tadaki; Oikawa, Shimpei

    2012-08-01

    Mean residence time (MRT) of plant nitrogen (N), which is an indicator of the expected length of time N newly taken up is retained before being lost, is an important component in plant nitrogen use. Here we extend the concept MRT to cover such variables as leaf number, leaf area, leaf dry mass, and nitrogen in the canopy. MRT was calculated from leaf duration (i.e., time integral of standing amount) divided by the total production of leaf variables. We determined MRT in a Xanthium canadense stand established with high or low N availability. The MRT of leaf number may imply longevity of leaves in the canopy. We found that the MRT of leaf area and dry mass were shorter than that of leaf number, while the MRT of leaf N was longer. The relatively longer MRT of leaf N was due to N resorption before leaf shedding. The MRT of all variables was longer at low N availability. Leaf productivity is the rate of canopy photosynthesis per unit amount of leaf variables, and multiplication of leaf productivity by MRT gives the leaf photosynthetic efficiency (canopy photosynthesis per unit production of leaf variables). The photosynthetic efficiency of leaf number implies the lifetime carbon gain of a leaf in the canopy. The analysis of plant-level N use efficiency by evaluating the N productivity and MRT is a well-established approach. Extension of these concepts to leaf number, area, mass, and N in the canopy will clarify the underlying logic in the study of leaf life span, leaf area development, and dry mass and N use in canopy photosynthesis. PMID:22349752

  7. Social life and sanitary risks: evolutionary and current ecological conditions determine waste management in leaf-cutting ants.

    PubMed

    Farji-Brener, Alejandro G; Elizalde, Luciana; Fernández-Marín, Hermógenes; Amador-Vargas, Sabrina

    2016-05-25

    Adequate waste management is vital for the success of social life, because waste accumulation increases sanitary risks in dense societies. We explored why different leaf-cutting ants (LCA) species locate their waste in internal nest chambers or external piles, including ecological context and accounting for phylogenetic relations. We propose that waste location depends on whether the environmental conditions enhance or reduce the risk of infection. We obtained the geographical range, habitat and refuse location of LCA from published literature, and experimentally determined whether pathogens on ant waste survived to the high soil temperatures typical of xeric habitats. The habitat of the LCA determined waste location after phylogenetic correction: species with external waste piles mainly occur in xeric environments, whereas those with internal waste chambers mainly inhabit more humid habitats. The ancestral reconstruction suggests that dumping waste externally is less derived than digging waste nest chambers. Empirical results showed that high soil surface temperatures reduce pathogen prevalence from LCA waste. We proposed that LCA living in environments unfavourable for pathogens (i.e. xeric habitats) avoid digging costs by dumping the refuse above ground. Conversely, in environments suitable for pathogens, LCA species prevent the spread of diseases by storing waste underground, presumably, a behaviour that contributed to the colonization of humid habitats. These results highlight the adaptation of organisms to the hygienic challenges of social living, and illustrate how sanitary behaviours can result from a combination of evolutionary history and current environmental conditions. PMID:27226469

  8. Knowledge of the Portuguese population on Basic Life Support and availability to attend training.

    PubMed

    Dixe, Maria Dos Anjos Coelho Rodrigues; Gomes, José Carlos Rodrigues

    2015-08-01

    OBJECTIVETo evaluate the level of knowledge and the availability of the Portuguese population to attend training in Basic Life Support (BLS) and identify factors related to their level of knowledge about BLS.METHODObservational study including 1,700 people who responded to a questionnaire containing data on demography, profession, training, interest in training and knowledge about BLS.RESULTSAmong 754 men and 943 women, only 17.8% (303) attended a course on BLS, but 95.6% expressed willingness to carry out the training. On average, they did not show good levels of knowledge on basic life support (correct answers in 25.9 ± 11.5 of the 64 indicators). Male, older respondents who had the training and those who performed BLS gave more correct answers, on average (p<0.01).CONCLUSIONThe skill levels of the Portuguese population are low, but people are available for training, hence it is important to develop training courses and practice to improve their knowledge. PMID:26353102

  9. Moisture Effects on Nitrogen Availability in Municipal Biosolids from End-of-Life Municipal Lagoons.

    PubMed

    Jeke, Nicholson N; Zvomuya, Francis; Ross, Lisette

    2015-11-01

    Nitrogen (N) availability affects plant biomass yield and, hence, phytoextraction of contaminants during phytoremediation of end-of-life municipal lagoons. End-of-life lagoons are characterized by fluctuating moisture conditions, but the effects on biosolid N dynamics have not been adequately characterized. This 130-d laboratory incubation investigated effects of three moisture levels (30, 60, and 90% water-filled pore space [WFPS]) on N mineralization (N) in biosolids from a primary (PB) and a secondary (SB) municipal lagoon cell. Results showed a net increase in N with time at 60% WFPS and a net decrease at 90% WFPS in PB, while N at 30% WFPS did not change significantly. Moisture level and incubation time had no significant effect on N in SB. Nitrogen mineralization rate in PB followed three-half-order kinetics. Potentially mineralizable N (N) in PB was significantly greater at 60% WFPS (222 mg kg) than at 30% WFPS (30 mg kg), but rate constants did not differ significantly between the moisture levels. Nitrogen mineralization in SB followed first-order kinetics, with N significantly greater at 60% WFPS (68.4 mg kg) and 90% WFPS (94.1 mg kg) than at 30% WFPS (32 mg kg). Low N in SB suggests high-N-demanding plants may eventually have limited effectiveness to remediate biosolids in the secondary cell. While high N in PB would provide sufficient N to support high biomass yield, phytoextraction potential is reduced under dry and near-saturated conditions. These results have important implications on the management of moisture during phytoextraction of contaminants in end-of-life municipal lagoons. PMID:26641340

  10. Leaf δ(15)N as a physiological indicator of the responsiveness of N2-fixing alfalfa plants to elevated [CO2], temperature and low water availability.

    PubMed

    Ariz, Idoia; Cruz, Cristina; Neves, Tomé; Irigoyen, Juan J; Garcia-Olaverri, Carmen; Nogués, Salvador; Aparicio-Tejo, Pedro M; Aranjuelo, Iker

    2015-01-01

    The natural (15)N/(14)N isotope composition (δ(15)N) of a tissue is a consequence of its N source and N physiological mechanisms in response to the environment. It could potentially be used as a tracer of N metabolism in plants under changing environmental conditions, where primary N metabolism may be complex, and losses and gains of N fluctuate over time. In order to test the utility of δ(15)N as an indicator of plant N status in N2-fixing plants grown under various environmental conditions, alfalfa (Medicago sativa L.) plants were subjected to distinct conditions of [CO2] (400 vs. 700 μmol mol(-1)), temperature (ambient vs. ambient +4°C) and water availability (fully watered vs. water deficiency-WD). As expected, increased [CO2] and temperature stimulated photosynthetic rates and plant growth, whereas these parameters were negatively affected by WD. The determination of δ(15)N in leaves, stems, roots, and nodules showed that leaves were the most representative organs of the plant response to increased [CO2] and WD. Depletion of heavier N isotopes in plants grown under higher [CO2] and WD conditions reflected decreased transpiration rates, but could also be related to a higher N demand in leaves, as suggested by the decreased leaf N and total soluble protein (TSP) contents detected at 700 μmol mol(-1) [CO2] and WD conditions. In summary, leaf δ(15)N provides relevant information integrating parameters which condition plant responsiveness (e.g., photosynthesis, TSP, N demand, and water transpiration) to environmental conditions. PMID:26322051

  11. Leaf δ15N as a physiological indicator of the responsiveness of N2-fixing alfalfa plants to elevated [CO2], temperature and low water availability

    PubMed Central

    Ariz, Idoia; Cruz, Cristina; Neves, Tomé; Irigoyen, Juan J.; Garcia-Olaverri, Carmen; Nogués, Salvador; Aparicio-Tejo, Pedro M.; Aranjuelo, Iker

    2015-01-01

    The natural 15N/14N isotope composition (δ15N) of a tissue is a consequence of its N source and N physiological mechanisms in response to the environment. It could potentially be used as a tracer of N metabolism in plants under changing environmental conditions, where primary N metabolism may be complex, and losses and gains of N fluctuate over time. In order to test the utility of δ15N as an indicator of plant N status in N2-fixing plants grown under various environmental conditions, alfalfa (Medicago sativa L.) plants were subjected to distinct conditions of [CO2] (400 vs. 700 μmol mol−1), temperature (ambient vs. ambient +4°C) and water availability (fully watered vs. water deficiency—WD). As expected, increased [CO2] and temperature stimulated photosynthetic rates and plant growth, whereas these parameters were negatively affected by WD. The determination of δ15N in leaves, stems, roots, and nodules showed that leaves were the most representative organs of the plant response to increased [CO2] and WD. Depletion of heavier N isotopes in plants grown under higher [CO2] and WD conditions reflected decreased transpiration rates, but could also be related to a higher N demand in leaves, as suggested by the decreased leaf N and total soluble protein (TSP) contents detected at 700 μmol mol−1 [CO2] and WD conditions. In summary, leaf δ15N provides relevant information integrating parameters which condition plant responsiveness (e.g., photosynthesis, TSP, N demand, and water transpiration) to environmental conditions. PMID:26322051

  12. Leaf age dependent changes in within-canopy variation in leaf functional traits: a meta-analysis.

    PubMed

    Niinemets, Ülo

    2016-05-01

    Within-canopy variation in leaf structural and photosynthetic characteristics is a major means by which whole canopy photosynthesis is maximized at given total canopy nitrogen. As key acclimatory modifications, leaf nitrogen content (N A) and photosynthetic capacity (A A) per unit area increase with increasing light availability in the canopy and these increases are associated with increases in leaf dry mass per unit area (M A) and/or nitrogen content per dry mass and/or allocation. However, leaf functional characteristics change with increasing leaf age during leaf development and aging, but the importance of these alterations for within-canopy trait gradients is unknown. I conducted a meta-analysis based on 71 canopies that were sampled at different time periods or, in evergreens, included measurements for different-aged leaves to understand how within-canopy variations in leaf traits (trait plasticity) depend on leaf age. The analysis demonstrated that in evergreen woody species, M A and N A plasticity decreased with increasing leaf age, but the change in A A plasticity was less suggesting a certain re-acclimation of A A to altered light. In deciduous woody species, M A and N A gradients in flush-type species increased during leaf development and were almost invariable through the rest of the season, while in continuously leaf-forming species, the trait gradients increased constantly with increasing leaf age. In forbs, N A plasticity increased, while in grasses, N A plasticity decreased with increasing leaf age, reflecting life form differences in age-dependent changes in light availability and in nitrogen resorption for growth of generative organs. Although more work is needed to improve the coverage of age-dependent plasticity changes in some plant life forms, I argue that the age-dependent variation in trait plasticity uncovered in this study is large enough to warrant incorporation in simulations of canopy photosynthesis through the growing period. PMID

  13. Life form-specific gradients in compound-specific hydrogen isotope ratios of modern leaf waxes along a North American Monsoonal transect.

    PubMed

    Berke, Melissa A; Tipple, Brett J; Hambach, Bastian; Ehleringer, James R

    2015-12-01

    The use of hydrogen isotope ratios (δ(2)H) of sedimentary n-alkanes from leaf waxes has become an important tool for reconstructing paleoenvironmental and ancient hydrologic conditions. Studies of modern plant waxes can elucidate driving ecological mechanisms behind geologic deposits. Here, we used a transect across the North American Monsoon region of the western USA from Tucson, Arizona to Salt Lake City, Utah to study variations in leaf wax δ(2)H among co-occurring plants. Three co-occurring life forms were selected: perennial shrub (rabbit brush, Chrysothamnus nauseosus; sagebrush, Artemisia tridentata); tree (Gambel's oak tree, Quercus gambelii); and annual (sunflower, Helianthus annuus). Our results showed that the distributions and abundances of n-alkanes in perennial plants were similar across all sites and generally did not vary with environmental conditions (e.g., precipitation and temperature). In contrast, variations in n-alkane δ(2)H were significantly correlated with the fraction of the annual precipitation coming during the summer monsoon period. We use a modified Craig-Gordon model to speculate on the possible drivers of the δ(2)H values of leaf wax n-alkanes of plants across the region. The model results suggest that the most likely explanation for variation in wax δ(2)H values was a combination of seasonal source water usage and subsequent environmental conditions. PMID:26310435

  14. Comparative analysis of the life cycle impact assessment of available cement inventories in the EU

    SciTech Connect

    Josa, Alejandro; Byars, Ewan

    2007-05-15

    Life cycle impact assessment (LCIA) is one of basic steps in life cycle assessment methodology (LCA). This paper presents a comparative study of the LCIA of different life cycle inventories (LCI) for EU cements. The analysis unit used is the manufacture of 1 kg of cement, from 'cradle to gate'. The impact categories considered are those resulting from the manufacture of cement and include greenhouse effects, acidification, eutrophication and summer and winter smog, amongst others. The results of the study highlighted some inconsistencies in existing inventories. As for the LCIA, the main environmental interventions related to cement manufacture were classified and characterised and their effect on different impact categories analysed. Differences observed in evaluation of the impact of cement type were essentially related to their clinker content.

  15. US Activities in Making Life Cycle Inventory Data More Available to Users

    EPA Science Inventory

    The demand for LCA studies continues to grow, although, the lack of reliable, transparent Life Cycle Inventory (LCI) data is hampering the wide-spread application of LCA. This paper will present activities related to the development and accessibility of process LCI data in the U...

  16. The Quantitative Measurement of Family Quality of Life: A Review of Available Instruments

    ERIC Educational Resources Information Center

    Hu, X.; Summers, J. A.; Turnbull, A.; Zuna, N.

    2011-01-01

    Background: Family quality of life (FQOL) has emerged as an important outcome of service delivery for individuals with disabilities and their families. The purpose of this review was to explore the disparity of scale development approaches between families with children with disabilities and families from other populations and identify strengths…

  17. The qTSN4 Effect on Flag Leaf Size, Photosynthesis and Panicle Size, Benefits to Plant Grain Production in Rice, Depending on Light Availability

    PubMed Central

    Fabre, Denis; Adriani, Dewi E.; Dingkuhn, Michael; Ishimaru, Tsutomu; Punzalan, Bermenito; Lafarge, Tanguy; Clément-Vidal, Anne; Luquet, Delphine

    2016-01-01

    Increasing rice yield potential is essential to secure world food supply. The quantitative trait locus qTSN4 was reported to achieve yield increases by enhancing both source and sink capacity. Three greenhouse experiments and one field experiment in the Philippines were conducted to study near-isogenic lines (NILs) in two genetic backgrounds, subjected to treatments with restricted light resources through shading (greenhouse) or population density (field and greenhouse). A consistent promotion of flag leaf width, leaf area and panicle size in terms of spikelet number was observed in the presence of qTSN4, regardless of environment. However, grain production per plant was enhanced only in one greenhouse experiment. An in-depth study demonstrated that increased flag leaf size in the presence of qTSN4 was associated with increased photosynthetic rates, along with lower SLA and greater N content per leaf weight and per area. This was emphasized under low light situation as the qTSN4-NILs did not express shade acclimation traits in contrast with the recipient varieties. The authors conclude that qTSN4 is a promising subject for further physiological studies, particularly under limited radiation. However, the QTL alone may not be a reliable source of increased yield potential because its effects at the plant and population scale are prone to genotype × environment interactions and the increased panicle size is compensated by the adaptive plasticity of other morphological traits. PMID:27242827

  18. The qTSN4 Effect on Flag Leaf Size, Photosynthesis and Panicle Size, Benefits to Plant Grain Production in Rice, Depending on Light Availability.

    PubMed

    Fabre, Denis; Adriani, Dewi E; Dingkuhn, Michael; Ishimaru, Tsutomu; Punzalan, Bermenito; Lafarge, Tanguy; Clément-Vidal, Anne; Luquet, Delphine

    2016-01-01

    Increasing rice yield potential is essential to secure world food supply. The quantitative trait locus qTSN4 was reported to achieve yield increases by enhancing both source and sink capacity. Three greenhouse experiments and one field experiment in the Philippines were conducted to study near-isogenic lines (NILs) in two genetic backgrounds, subjected to treatments with restricted light resources through shading (greenhouse) or population density (field and greenhouse). A consistent promotion of flag leaf width, leaf area and panicle size in terms of spikelet number was observed in the presence of qTSN4, regardless of environment. However, grain production per plant was enhanced only in one greenhouse experiment. An in-depth study demonstrated that increased flag leaf size in the presence of qTSN4 was associated with increased photosynthetic rates, along with lower SLA and greater N content per leaf weight and per area. This was emphasized under low light situation as the qTSN4-NILs did not express shade acclimation traits in contrast with the recipient varieties. The authors conclude that qTSN4 is a promising subject for further physiological studies, particularly under limited radiation. However, the QTL alone may not be a reliable source of increased yield potential because its effects at the plant and population scale are prone to genotype × environment interactions and the increased panicle size is compensated by the adaptive plasticity of other morphological traits. PMID:27242827

  19. Stirling engine - Available tools for long-life assessment. [for space propulsion

    NASA Technical Reports Server (NTRS)

    Halford, Gary R.; Bartolotta, Paul A.

    1991-01-01

    A review is presented for the durability approaches applicable to long-time life assessment of Stirling engine hot-section components. The crucial elements are experimental techniques for generating long-time materials property data (both monotonic and cyclic flow and failure properties); analytic representations of slow strain rate material stress-strain response characteristics (monotonic and cyclic constitutive relations) at high temperatures and low stresses and strains; analytic creep-fatigue-environmental interaction life prediction methods applicable to long lifetimes at high temperatures and small stresses and strains; and experimental verification of life predictions. Long-lifetime design criteria for materials of interest are woefully lacking. Designing against failures due to creep, creep-rupture, fatigue, environmental attack, and creep-failure-environmental interaction will require considerable extrapolation. Viscoplastic constitutive models and time-temperature parameters will have to be calibrated for the hot-section materials of interest. Analysis combined with limited verification testing in a short-time regime will be required to build confidence in long-lifetime durability models.

  20. Leveraging Available Data to Support Extension of Transportation Packages Service Life

    SciTech Connect

    Dunn, K.; Abramczyk, G.; Bellamy, S.; Daugherty, W.; Hackney, B.; Hoffman, E.; Skidmore, E.; Stefek, T.

    2012-06-12

    Data obtained from testing shipping package materials have been leveraged to support extending the service life of select shipping packages while in nuclear materials transportation. Increasingly, nuclear material inventories are being transferred to an interim storage location where they will reside for extended periods of time. Use of a shipping package to store nuclear materials in an interim storage location has become more attractive for a variety of reasons. Shipping packages are robust and have a qualified pedigree for their performance in normal operation and accident conditions within the approved shipment period and storing nuclear material within a shipping package results in reduced operations for the storage facility. However, the shipping package materials of construction must maintain a level of integrity as specified by the safety basis of the storage facility through the duration of the storage period, which is typically well beyond the one year transportation window. Test programs have been established to obtain aging data on materials of construction that are the most sensitive/susceptible to aging in certain shipping package designs. The collective data are being used to support extending the service life of shipping packages in both transportation and storage.

  1. Resource availability, mortality, and fertility: a path analytic approach to global life-history variation.

    PubMed

    Caudell, Mark A; Quinlan, Robert J

    2012-04-01

    Humans exhibit considerable diversity in timing and rate of reproduction. Life-history theory (LHT) suggests that ecological cues of resource richness and survival probabilities shape human phenotypes across populations. Populations experiencing high extrinsic mortality due to uncertainty in resources should exhibit faster life histories. Here we use a path analytic (PA) approach informed by LHT to model the multiple pathways between resources, mortality rates, and reproductive behavior in 191 countries. Resources that account for the most variance in population mortality rates are predicted to explain the most variance in total fertility rates. Results indicate that resources (e.g., calories, sanitation, education, and health-care expenditures) influence fertility rates in paths through communicable and noncommnunicable diseases. Paths acting through communicable disease are more strongly associated with fertility than are paths through noncommunicable diseases. These results suggest that a PA approach may help disaggregate extrinsic and intrinsic mortality factors in cross-cultural analyses. Such knowledge may be useful in developing targeted policies to decrease teenage pregnancy, total fertility rates, and thus issues associated with overpopulation. PMID:22708816

  2. Species performance: the relationship between nutrient availability, life history traits, and stress

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The role soil nutrient availability plays in our ability to restore invasive plant dominated systems is not as straightforward as it initially appears. The objectives of this chapter are to: 1) Examine current paradigms and assumptions about how nutrient availability influences the relative perform...

  3. Evaluation available encapsulation materials for low-cost long-life silicon photovoltaic arrays

    NASA Technical Reports Server (NTRS)

    Carmichael, D. C.; Gaines, G. B.; Noel, G. T.; Sliemers, F. A.; Nance, G. P.; Bunk, A. R.; Brockway, M. C.

    1978-01-01

    Experimental evaluation of selected encapsulation designs and materials based on an earlier study which have potential for use in low cost, long-life photovoltaic arrays are reported. The performance of candidate materials and encapsulated cells were evaluated principally for three types of encapsulation designs based on their potentially low materials and processing costs: (1) polymeric coatings, transparent conformal coatings over the cell with a structural-support substrate; (2) polymeric film lamination, cells laminated between two films or sheets of polymeric materials; and (3) glass-covered systems, cells adhesively bonded to a glass cover (superstrate) with a polymeric pottant and a glass or other substrate material. Several other design types, including those utilizing polymer sheet and pottant materials, were also included in the investigation.

  4. Effectiveness of two-sided UV-C treatments in inhibiting natural microflora and extending the shelf-life of minimally processed 'Red Oak Leaf' lettuce.

    PubMed

    Allende, Ana; McEvoy, James L; Luo, Yaguang; Artes, Francisco; Wang, Chien Y

    2006-05-01

    The use of UV-C radiation treatments to inhibit the microbial growth and extend the shelf-life of minimally processed 'Red Oak Leaf' lettuce was investigated. Initially, UV-C resistance of 20 bacterial strains from different genera often associated with fresh produce (Enterobacter, Erwinia, Escherichia, Leuconostoc, Pantoea, Pseudomonas, Rahnela, Salmonella, Serratia and Yersinia) were tested in vitro. Most of the bacterial strains were inhibited with the minimum dose (30 J m(-2)). Erwinia carotovora, Leuconostoc carnosum, Salmonella typhimurium, and Yersinia aldovae were the most resistant strains requiring a UV-C dose of 85 J m(-2) to completely inhibit growth. An in vivo study consisted of treating minimally processed 'Red Oak Leaf' lettuce (Lactuca sativa) with UV-C at three radiation doses (1.18, 2.37 and 7.11 kJ m(-2)) on each side of the leaves and storing the product under passive MAP conditions at 5 degrees C for up to 10 days. The gas composition inside packages varied significantly among the treatments, with CO2 concentrations positively and O2 concentrations negatively correlating with the radiation dose. All the radiation doses were effective in reducing the natural microflora of the product, although the highest doses showed the greatest microbial inhibitions. Taking into account the microbial limit set by Spanish legislation [Boletín Oficial del Estado (BOE), 2001. Normas de higiene para la elaboración, distribución y comercio de comidas preparadas, Madrid, Spain, Real Decreto 3484/2000, pp. 1435-1441], all UV-C treatments extended the shelf-life of the product. However, the 7.11 kJ m(-2) dose induced tissue softening and browning after 7 days of storage at 5 degrees C. Therefore, the use of two sided UV-C radiation, at the proper dose, is effective in reducing the natural microflora and extending the shelf-life of minimally processed 'Red Oak Leaf' lettuce. PMID:16943010

  5. Regional scale impacts of Tamarix leaf beetles (Diorhabda carinulata) on the water availability of western U.S. rivers as determined by multi-scale remote sensing methods

    USGS Publications Warehouse

    Nagler, Pamela L.; Brown, Tim; Hultine, Kevin R.; van Riper, Charles, III; Bean, Daniel W.; Dennison, Philip E.; Murray, R. Scott; Glenn, Edward P.

    2012-01-01

    Tamarix leaf beetles (Diorhabda carinulata) have been widely released on western U.S. rivers to control introduced shrubs in the genus Tamarix. Part of the motivation to control Tamarix is to salvage water for human use. Information is needed on the impact of beetles on Tamarix seasonal leaf production and subsequent water use overwide areas andmultiple cycles of annual defoliation.Herewe combine ground data with high resolution phenocam imagery and moderate resolution (Landsat) and coarser resolution (MODIS) satellite imagery to test the effects of beetles on Tamarix evapotranspiration (ET) and leaf phenology at sites on six western rivers. Satellite imagery covered the period 2000 to 2010 which encompassed years before and after beetle release at each study site. Phenocam images showed that beetles reduced green leaf cover of individual canopies by about 30% during a 6-8 week period in summer, but plants produced new leaves after beetles became dormant in August, and over three years no net reduction in peak summer leaf production was noted. ETwas estimated by vegetation index methods, and both Landsat and MODIS analyses showed that beetles reduced ET markedly in the first year of defoliation, but ET recovered in subsequent years. Over all six sites, ET decreased by 14% to 15% by Landsat and MODIS estimates, respectively. However, resultswere variable among sites, ranging fromno apparent effect on ET to substantial reduction in ET. Baseline ET rates before defoliation were low, 394 mmyr-1 by Landsat and 314 mm yr-1 by MODIS estimates (20-25% of potential ET), further constraining the amount of water that could be salvaged. Beetle-Tamarix interactions are in their early stage of development on this continent and it is too soon to predict the eventual extent towhich Tamarix populationswill be reduced. The utility of remote sensing methods for monitoring defoliation was constrained by the small area covered by each phenocamimage, the low temporal resolution of

  6. Efficacy of mint (Mentha arvensis) leaf and citrus (Citrus aurantium) peel extracts as natural preservatives for shelf life extension of chill stored Indian mackerel.

    PubMed

    Viji, Pankyamma; Binsi, Puthanpurakkal Kizhakkathil; Visnuvinayagam, Sivam; Bindu, Jaganath; Ravishankar, Chandragiri Nagarajarao; Srinivasa Gopal, Teralandur Krishnaswamy

    2015-10-01

    Efficacy of mint (Mentha arvensis) leaf and citrus (Citrus aurantium) peel extracts in retarding the quality changes in Indian mackerel during chilled storage was investigated. Mint leaf extract showed higher quantity of phenolics and superior in-vitro antioxidant activities than citrus peel extract. Gutted mackerel were given a dip treatment in mint extract (0.5 %, w/v) and citrus extract (1 % w/v), packed in LDPE pouches and stored at 0-2 °C. The biochemical quality indices viz. total volatile base nitrogen (TVB-N), trimethylamine nitrogen (TMA-N), free fattyacids (FFA) were significantly (p < 0.05) lower in mint extract (ME) treated fishes compared to citrus extract (CE) treated and control fishes (C) without any treatment. Plant extract treatment significantly inhibited lipid oxidation in mackerel as indicated by peroxide value (PV) and thiobarbituric acid reactive substances (TBARS). Aerobic plate count (APC) was markedly higher in C group followed by CE group throughout the storage period. As per sensory evaluation, shelf life of Indian mackerel was determined to be 11-13 days for C group, 13-15 days for CE group and 16-17 days for ME group, during storage at 0-2 °C. PMID:26396373

  7. Developmental plasticity of growth and digestive efficiency in dependence of early-life food availability

    PubMed Central

    Kotrschal, Alexander; Szidat, Sönke; Taborsky, Barbara

    2014-01-01

    Nutrition is a potent mediator of developmental plasticity. If food is scarce, developing organisms may invest into growth to outgrow size-dependent mortality (short-term benefit) and/or into an efficient digestion system (long-term benefit). We investigated this potential trade-off, by determining the influence of food availability on juvenile body and organ growth, and on adult digestive efficiency in the cichlid fish Simochromis pleurospilus. We reared two groups of fish at constant high or low food rations, and we switched four other groups between these two rations at an early and late juvenile period. We measured juvenile growth and organ sizes at different developmental stages and determined adult digestive efficiency. Fish kept at constant, high rations grew considerably faster than low-food fish. Nevertheless, S. pleurospilus partly buffered the negative effects of low food availability by developing heavier digestive organs, and they were therefore more efficient in digesting their food as adults. Results of fish exposed to a ration switch during either the early or late juvenile period suggest (i) that the ability to show compensatory growth after early exposure to low food availability persists during the juvenile period, (ii) that digestive efficiency is influenced by varying juvenile food availability during the late juvenile phase and (iii) that the efficiency of the adult digestive system is correlated with the growth rate during a narrow time window of juvenile period. PMID:25866430

  8. Mining Available Data from the United States Environmental Protection Agency to Support Rapid Life Cycle Inventory Modeling of Chemical Manufacturing.

    PubMed

    Cashman, Sarah A; Meyer, David E; Edelen, Ashley N; Ingwersen, Wesley W; Abraham, John P; Barrett, William M; Gonzalez, Michael A; Randall, Paul M; Ruiz-Mercado, Gerardo; Smith, Raymond L

    2016-09-01

    Demands for quick and accurate life cycle assessments create a need for methods to rapidly generate reliable life cycle inventories (LCI). Data mining is a suitable tool for this purpose, especially given the large amount of available governmental data. These data are typically applied to LCIs on a case-by-case basis. As linked open data becomes more prevalent, it may be possible to automate LCI using data mining by establishing a reproducible approach for identifying, extracting, and processing the data. This work proposes a method for standardizing and eventually automating the discovery and use of publicly available data at the United States Environmental Protection Agency for chemical-manufacturing LCI. The method is developed using a case study of acetic acid. The data quality and gap analyses for the generated inventory found that the selected data sources can provide information with equal or better reliability and representativeness on air, water, hazardous waste, on-site energy usage, and production volumes but with key data gaps including material inputs, water usage, purchased electricity, and transportation requirements. A comparison of the generated LCI with existing data revealed that the data mining inventory is in reasonable agreement with existing data and may provide a more-comprehensive inventory of air emissions and water discharges. The case study highlighted challenges for current data management practices that must be overcome to successfully automate the method using semantic technology. Benefits of the method are that the openly available data can be compiled in a standardized and transparent approach that supports potential automation with flexibility to incorporate new data sources as needed. PMID:27517866

  9. Theoretical life history responses of juvenile Oncorhynchus mykiss to changes in food availability using a dynamic state-dependent approach

    USGS Publications Warehouse

    Romine, Jason G.; Benjamin, Joseph R.; Perry, Russell W.; Casal, Lynne; Connolly, Patrick J.; Sauter, Sally S.

    2013-01-01

    Marine subsidies can play an important role in the growth, survival, and migratory behavior of rearing juvenile salmonids. Availability of high-energy, marine-derived food sources during critical decision windows may influence the timing of emigration or the decision to forego emigration completely and remain in the freshwater environment. Increasing growth and growth rate during these decision windows may result in an altered juvenile population structure, which will ultimately affect the adult population age-structure. We used a state dependent model to understand how the juvenile Oncorhynchus mykiss population structure may respond to increased availability of salmon eggs in their diet during critical decision windows. Our models predicted an increase in smolt production until coho salmon eggs comprised more than 50 percent of juvenile O. mykiss diet at the peak of the spawning run. At higher-than intermediate levels of egg consumption, smolt production decreased owing to increasing numbers of fish adopting a resident life-history strategy. Additionally, greater growth rates decreased the number of age-3 smolts and increased the number of age-2 smolts. Increased growth rates with higher egg consumption also decreased the age at which fish adopted the resident pathway. Our models suggest that the introduction of a high-energy food source during critical periods of the year could be sufficient to increase smolt production.

  10. Vitamins, stress and growth: the availability of antioxidants in early life influences the expression of cryptic genetic variation.

    PubMed

    Kim, S-Y; Noguera, J C; Tato, A; Velando, A

    2013-06-01

    Environmental inputs during early development can shape the expression of phenotypes, which has long-lasting consequences in physiology and life history of an organism. Here, we study whether experimentally manipulated availability of dietary antioxidants, vitamins C and E, influences the expression of genetic variance for antioxidant defence, endocrine signal and body mass in yellow-legged gull chicks using quantitative genetic models based on full siblings. Our experimental study in a natural population reveals that the expression of genetic variance in total antioxidant capacity in plasma increased in chicks supplemented with vitamins C and E despite the negligible effects on the average phenotype. This suggests that individuals differ in their ability to capture and transport dietary antioxidants or to respond to these extra resources, and importantly, this ability has a genetic basis. Corticosterone level in plasma and body mass were negatively correlated at the phenotypic level. Significant genetic variance of corticosterone level appeared only in control chicks nonsupplemented with vitamins, suggesting that the genetic variation of endocrine system, which transmits environmental cues to adaptively control chick development, appeared in stressful conditions (i.e. poor antioxidant availability). Therefore, environmental inputs may shape evolutionary trajectories of antioxidant capacity and endocrine system by affecting the expression of cryptic genetic variation. PMID:23517061

  11. Management practices for end-of-life cathode ray tube glass: Review of advances in recycling and best available technologies.

    PubMed

    Iniaghe, Paschal O; Adie, Gilbert U

    2015-11-01

    Cathode ray tubes are image display units found in computer monitors and televisions. In recent years, cathode ray tubes have been generated as waste owing to the introduction of newer and advanced technologies in image displays, such as liquid crystal displays and high definition televisions, among others. Generation and subsequent disposal of end-of-life cathode ray tubes presents a challenge owing to increasing volumes and high lead content embedded in the funnel and neck sections of the glass. Disposal in landfills and open dumping are anti-environmental practices considering the large-scale contamination of environmental media by the potential of toxic metals leaching from glass. Mitigating such environmental contamination will require sound management strategies that are environmentally friendly and economically feasible. This review covers existing and emerging management practices for end-of-life cathode ray tubes. An in-depth analysis of available technologies (glass smelting, detoxification of cathode ray tube glass, lead extraction from cathode ray tube glass) revealed that most of the techniques are environmentally friendly, but are largely confined to either laboratory scale, or are often limited owing to high cost to mount, or generate secondary pollutants, while a closed-looped method is antiquated. However, recycling in cementitious systems (cement mortar and concrete) gives an added advantage in terms of quantity of recyclable cathode ray tube glass at a given time, with minimal environmental and economic implications. With significant quantity of waste cathode ray tube glass being generated globally, cementitious systems could be economically and environmentally acceptable as a sound management practice for cathode ray tube glass, where other technologies may not be applicable. PMID:26463115

  12. 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

  13. Warming does not stimulate mitochondrial respiration and it responds to leaf carbohydrates availability in soybean plants grown under elevated CO2 concentrations

    NASA Astrophysics Data System (ADS)

    Ruiz Vera, U. M.; Gomez-Casanovas, N.; Bernacchi, C.; Ort, D. R.; Siebers, M.

    2015-12-01

    There is a lack of understanding on the mechanism underlying the response of mitochondrial respiration (Rs) to the single and combined effects of increasing CO2 concentration ([CO2]) and warming. We investigated the response of Rs to the single and combined effects of elevated [CO2] and warming in soybean plants over a complete growing season using Temperature by Free Air CO2 enrichment technology under field conditions. The treatments were: control, elevated [CO2] (eC), high temperature (eT), and elevated [CO2]+high temperature (eT+eC). Given that photosynthetic rates in eT+eC grown plants were not higher than in plants grown under eC, we hypothesized that Rs would increase only slightly in plants grown under eT+eC compared to eC plants, due to the increase of temperature. Contrary to our prediction, our preliminary results showed that plants grown under the warming treatments had low Rs, thus eT+eC had lower Rs than eC. The response of Rs to these factors was consistent at two different plant high levels (canopy and five nodes down the canopy). Changes in Rs were explained by variations in the carbohydrate content. Our results indicate that the response of Rs to changes in [CO2] and temperature will depend on the carbohydrate availability of plant tissues and thus on how photosynthesis is affected by this environmental factors.

  14. Climatic Controls on Leaf Nitrogen Content and Implications for Biochemical Modeling.

    NASA Astrophysics Data System (ADS)

    Tcherednichenko, I. A.; White, M.; Bastidas, L.

    2007-12-01

    Leaf nitrogen (N) content, expressed as percent total nitrogen per unit of leaf dry mass, is a widely used parameter in biochemical modeling, due mainly to its role as a potentially limiting factor for photosynthesis. The amount of nitrogen, however, does not occur in a fixed amount in every leaf, but rather varies continuously with the leaf life cycle, in constant response to soil-root-stem-leaf-climate interactions and demand for growth. Moreover, while broad data on leaf N has become available it is normally measured under ambient conditions with consequent difficulty for distinguishing between genetic and time specific environmental effects. In the present work we: 1) Investigate the theoretical variation of leaf mass, specific heat capacity and leaf thickness of full sun-expanded leaves as a regulatory mechanism to ensure thermal survival along with long-term climatic radiation/temperature gradient; and discuss nitrogen and carbon controls on leaf thickness. 2) Based on possible states of partition between nitrogenous and non-nitrogenous components of a leaf we further derive probability density functions (PDFs) of nitrogen and carbon content and assess the effect of water and nutrient uptake on the PDFs. 3) Translate the results to spatially explicit representation over the conterminous USA at 1 km spatial resolution by providing maximum potential values of leaf N of fully expanded leaf optimally suited for long term climatic averages values and soils conditions. Implications for potential presence of inherently slow/fast growing species are discussed along with suitability of results for use by biochemical models.

  15. 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

  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. 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.

  18. News and Views: VLT detects convincing signs of life - on Earth; Lemaître honoured; Sun gets active; Earthquakes on Islay; Herschel family papers available online

    NASA Astrophysics Data System (ADS)

    2012-04-01

    European Southern Observatory data from the Very Large Telescope have enabled astronomers to say with confidence that they can detect signs of life on Earth using spectropolarimetry of earthshine: light from the Earth's atmosphere reflected from the Moon. This is an important step towards detecting life on exoplanets. A collection of archive materials from the family of Sir John F W Herschel (1792-1871) is now available for study at Harry Ransom Center at the University of Texas at Austin. The collection includes much of John Herschel's correspondence as well as examples of his cyanotypes.

  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. 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. Effects of grazing on leaf traits and ecosystem functioning in Inner Mongolia grasslands: scaling from species to community

    NASA Astrophysics Data System (ADS)

    Zheng, S. X.; Ren, H. Y.; Lan, Z. C.; Li, W. H.; Wang, K. B.; Bai, Y. F.

    2010-03-01

    Understanding the mechanistic links between environmental drivers, human disturbance, plant functional traits, and ecosystem properties is a fundamental aspect of biodiversity-ecosystem functioning research. Recent studies have focused mostly on leaf-level traits or community-level weighted traits to predict species responses to grazing and the consequent change in ecosystem functioning. However, studies of leaf-level traits or community-level weighted traits seldom identify the mechanisms linking grazing impact on leaf traits to ecosystem functioning. Here, using a multi-organization-level approach, we examined the effects of grazing on leaf traits (i.e., leaf area, leaf dry mass and specific leaf area) and ecosystem functioning across six communities of three vegetation types along a soil moisture gradient in the Xilin River Basin of Inner Mongolia grassland, China. Our results showed that the effects of grazing on leaf traits differed substantially when scaling up from leaf-level to species, functional group (i.e., life forms and water ecotype types), and community levels; and they also varied with vegetation type or site conditions. The effects of grazing on leaf traits diminished progressively along the hierarchy of organizational levels in the meadow, whereas the impacts were predominantly negative and the magnitude of the effects increased considerably at higher organizational levels in the typical steppe. Soil water and nutrient availability, functional trade-offs between leaf size and number of leaves per individual, and differentiation in avoidance and tolerance strategies among coexisting species are likely to be responsible for the observed responses of leaf traits to grazing at different levels of organization and among vegetation types. Our findings also demonstrate that, at both the functional group and community levels, standing aboveground biomass increased with leaf area and specific leaf area. Compared with the large changes in leaf traits and

  2. Size-dependent changes in leaf and wood chemical traits in two Caribbean rainforest trees.

    PubMed

    Martin, Adam R; Thomas, Sean C

    2013-12-01

    Tree functional traits and their link to patterns of growth and demography are central to informing trait-based analyses of forest communities, and mechanistic models of forest dynamics. However, few data are available on how functional traits in trees vary through ontogeny, particularly in tropical species; and less is known about how patterns of size-dependent changes in traits may differ across species of contrasting life-history strategies. Here we describe size-dependent variation in seven leaf functional traits and four wood chemical traits, in two Dominican rainforest tree species (Dacryodes excelsa Vahl. and Miconia mirabilis (Aubl.) L.O. Williams), ranging from small saplings to the largest canopy trees. With one exception, all traits showed pronounced variation with tree size (diameter at breast height, DBH). Leaf mass per area (LMA), thickness and tissue density increased monotonically with DBH in both species. Leaf area, leaf nitrogen (N) and carbon (C) : nitrogen (N) ratios also varied significantly with DBH; however, these patterns were unimodal, with peak trait values preceding the DBH at reproductive onset in both species. Size-dependent changes in leaf structural traits (LMA and leaf thickness) were generally similar in both species, while traits associated with leaf-level investment in C gain (leaf area, leaf C : N ratio) showed contrasting ontogenetic trends between species. Wood starch concentration varied with DBH in both species, also showing unimodal patterns with peaks preceding size at reproductive onset. Wood C concentration increased linearly with DBH in both species, though significantly only in M. mirabilis. Size-dependent patterns in wood chemical traits were similar between both species. Our data demonstrate pronounced variation in functional traits through tree ontogeny, probably due to a combination of environmental factors and shifts in resource allocation. Such ontogenetic variation is comparable in magnitude with interspecific

  3. Contrasting seasonal leaf habits of canopy trees between tropical dry-deciduous and evergreen forests in Thailand.

    PubMed

    Ishida, Atsushi; Diloksumpun, Sapit; Ladpala, Phanumard; Staporn, Duriya; Panuthai, Samreong; Gamo, Minoru; Yazaki, Kenichi; Ishizuka, Moriyoshi; Puangchit, Ladawan

    2006-05-01

    We compared differences in leaf properties, leaf gas exchange and photochemical properties between drought-deciduous and evergreen trees in tropical dry forests, where soil nutrients differed but rainfall was similar. Three canopy trees (Shorea siamensis Miq., Xylia xylocarpa (Roxb.) W. Theob. and Vitex peduncularis Wall. ex Schauer) in a drought-deciduous forest and a canopy tree (Hopea ferrea Lanessan) in an evergreen forest were selected. Soil nutrient availability is lower in the evergreen forest than in the deciduous forest. Compared with the evergreen tree, the deciduous trees had shorter leaf life spans, lower leaf masses per area, higher leaf mass-based nitrogen (N) contents, higher leaf mass-based photosynthetic rates (mass-based P(n)), higher leaf N-based P(n), higher daily maximum stomatal conductance (g(s)) and wider conduits in wood xylem. Mass-based P(n) decreased from the wet to the dry season for all species. Following onset of the dry season, daily maximum g(s) and sensitivity of g(s) to leaf-to-air vapor pressure deficit remained relatively unchanged in the deciduous trees, whereas both properties decreased in the evergreen tree during the dry season. Photochemical capacity and non-photochemical quenching (NPQ) of photosystem II (PSII) also remained relatively unchanged in the deciduous trees even after the onset of the dry season. In contrast, photochemical capacity decreased and NPQ increased in the evergreen tree during the dry season, indicating that the leaves coped with prolonged drought by down-regulating PSII. Thus, the drought-avoidant deciduous species were characterized by high N allocation for leaf carbon assimilation, high water use and photoinhibition avoidance, whereas the drought-tolerant evergreen was characterized by low N allocation for leaf carbon assimilation, conservative water use and photoinhibition tolerance. PMID:16452078

  4. Shelf-life extension of refrigerated sea bass slices wrapped with fish protein isolate/fish skin gelatin-ZnO nanocomposite film incorporated with basil leaf essential oil.

    PubMed

    Arfat, Yasir Ali; Benjakul, Soottawat; Vongkamjan, Kitiya; Sumpavapol, Punnanee; Yarnpakdee, Suthasinee

    2015-10-01

    Microbiological, chemical and sensory changes of sea bass slices wrapped with fish protein isolate (FPI)/fish skin gelatin (FSG) films incorporated with 3 % ZnO nanoparticles (ZnONP) (w/w, based on protein content) and 100 % basil leaf essential oil (BEO) (w/w, based on protein content) during storage of 12 days at 4 °C were investigated. Sea bass slices wrapped with FPI/FSG-ZnONP-BEO film had the lowest growth of psychrophilic bacteria, lactic acid bacteria and spoilage microorganisms including Pseudomonas , H2S-producing bacteria and Enterobacteriaceae throughout storage of 12 days in comparison with those wrapped with FPI/FSG-BEO, FPI/FSG-ZnONP, FPI/FSG film, polypropylene film (PP film) and the control (without wrapping), respectively (P < 0.05). Lowered increases in pH, total volatile base, peroxide value and TBARS value were found in FPI/FSG-ZnO-BEO film wrapped samples, compared with others (P < 0.05). Sensory evaluation revealed that shelf-life of sea bass slices was longest for samples wrapped with FPI/FSG-ZnONP-BEO film (12 days), as compared to the control (6 days) (P < 0.05). PMID:26396365

  5. 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.

  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. Leaf mineral nutrient remobilization during leaf senescence and modulation by nutrient deficiency

    PubMed Central

    Maillard, Anne; Diquélou, Sylvain; Billard, Vincent; Laîné, Philippe; Garnica, Maria; Prudent, Marion; Garcia-Mina, José-Maria; Yvin, Jean-Claude; Ourry, Alain

    2015-01-01

    Higher plants have to cope with fluctuating mineral resource availability. However, strategies such as stimulation of root growth, increased transporter activities, and nutrient storage and remobilization have been mostly studied for only a few macronutrients. Leaves of cultivated crops (Zea mays, Brassica napus, Pisum sativum, Triticum aestivum, Hordeum vulgare) and tree species (Quercus robur, Populus nigra, Alnus glutinosa) grown under field conditions were harvested regularly during their life span and analyzed to evaluate the net mobilization of 13 nutrients during leaf senescence. While N was remobilized in all plant species with different efficiencies ranging from 40% (maize) to 90% (wheat), other macronutrients (K–P–S–Mg) were mobilized in most species. Ca and Mn, usually considered as having low phloem mobility were remobilized from leaves in wheat and barley. Leaf content of Cu–Mo–Ni–B–Fe–Zn decreased in some species, as a result of remobilization. Overall, wheat, barley and oak appeared to be the most efficient at remobilization while poplar and maize were the least efficient. Further experiments were performed with rapeseed plants subjected to individual nutrient deficiencies. Compared to field conditions, remobilization from leaves was similar (N–S–Cu) or increased by nutrient deficiency (K–P–Mg) while nutrient deficiency had no effect on Mo–Zn–B–Ca–Mn, which seemed to be non-mobile during leaf senescence under field conditions. However, Ca and Mn were largely mobilized from roots (-97 and -86% of their initial root contents, respectively) to shoots. Differences in remobilization between species and between nutrients are then discussed in relation to a range of putative mechanisms. PMID:26029223

  8. Leaf mineral nutrient remobilization during leaf senescence and modulation by nutrient deficiency.

    PubMed

    Maillard, Anne; Diquélou, Sylvain; Billard, Vincent; Laîné, Philippe; Garnica, Maria; Prudent, Marion; Garcia-Mina, José-Maria; Yvin, Jean-Claude; Ourry, Alain

    2015-01-01

    Higher plants have to cope with fluctuating mineral resource availability. However, strategies such as stimulation of root growth, increased transporter activities, and nutrient storage and remobilization have been mostly studied for only a few macronutrients. Leaves of cultivated crops (Zea mays, Brassica napus, Pisum sativum, Triticum aestivum, Hordeum vulgare) and tree species (Quercus robur, Populus nigra, Alnus glutinosa) grown under field conditions were harvested regularly during their life span and analyzed to evaluate the net mobilization of 13 nutrients during leaf senescence. While N was remobilized in all plant species with different efficiencies ranging from 40% (maize) to 90% (wheat), other macronutrients (K-P-S-Mg) were mobilized in most species. Ca and Mn, usually considered as having low phloem mobility were remobilized from leaves in wheat and barley. Leaf content of Cu-Mo-Ni-B-Fe-Zn decreased in some species, as a result of remobilization. Overall, wheat, barley and oak appeared to be the most efficient at remobilization while poplar and maize were the least efficient. Further experiments were performed with rapeseed plants subjected to individual nutrient deficiencies. Compared to field conditions, remobilization from leaves was similar (N-S-Cu) or increased by nutrient deficiency (K-P-Mg) while nutrient deficiency had no effect on Mo-Zn-B-Ca-Mn, which seemed to be non-mobile during leaf senescence under field conditions. However, Ca and Mn were largely mobilized from roots (-97 and -86% of their initial root contents, respectively) to shoots. Differences in remobilization between species and between nutrients are then discussed in relation to a range of putative mechanisms. PMID:26029223

  9. Methods for Assessing the Impact of Fog Oil Smoke on Availability, Palatability, & Food Quality of Relevant Life Stages of Insects for Threatened and Endangered Species

    SciTech Connect

    Driver, Crystal J.; Strenge, Dennis L.; Su, Yin-Fong; Cullinan, Valerie I.; Herrington, Ricky S.; Saunders, Danielle L.; Rogers, Lee E.

    2007-04-01

    A methodology for quantifying population dynamics and food source value of insect fauna in areas subjected to fog oil smoke was developed. Our approach employed an environmentally controlled re-circulating wind tunnel outfitted with a high-heat vaporization and re-condensation fog oil generator that has been shown to produce aerosols of comparable chemistry and droplet-size distribution as those of field releases of the smoke. This method provides reproducible exposures of insects under realistic climatic and environmental conditions to fog oil aerosols that duplicate chemical and droplet-size characteristics of field releases of the smoke. The responses measured take into account reduction in food sources due to death and to changes in availability of relevant life stages of insects that form the prey base for the listed Threatened and Endangered Species. The influence of key environmental factors, wind speed and canopy structure on these responses were characterized. Data generated using this method was used to develop response functions related to particle size, concentration, wind speed, and canopy structure that will allow military personnel to assess and manage impacts to endangered species from fog oil smoke used in military training.

  10. Use of commercially available antimicrobial compounds for prevention of Listeria monocytogenes growth in ready-to-eat minced tuna and salmon roe during shelf life.

    PubMed

    Takahashi, Hajime; Kuramoto, Shintaro; Miya, Satoko; Koiso, Hiroaki; Kuda, Takashi; Kimura, Bon

    2011-06-01

    Listeria monocytogenes found in minced tuna and fish roe can cause listeriosis. These products are classified in category B according to the Codex Alimentarius Commission, i.e., ready-to-eat foods in which L. monocytogenes growth can occur. We investigated the effectiveness of nisin and other commercially available antimicrobial compounds (lysozyme, ε-polylysine, and chitosan) for prevention of L. monocytogenes growth during the expected shelf life of raw minced tuna and salmon roe products. Food samples inoculated with L. monocytogenes were incubated with each antimicrobial at 10°C for 7 days or at 25°C for 12 h. Nisaplin (an antimicrobial containing nisin) effectively inhibited L. monocytogenes growth in minced tuna at 500 ppm and in salmon roe at 250 ppm within their standard shelf lives. The effective concentration of each antimicrobial was determined: 2,000 ppm for ART FRESH 50/50 (containing lysozyme) and SAN KEEPER No. 381 (containing ε-polylysine) and 10,000 ppm for SAN KEEPER K-3 (containing chitosan). PMID:21669079

  11. 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....

  12. Understanding and predicting global leaf phenology using satellite observations of vegetation

    NASA Astrophysics Data System (ADS)

    Caldararu, Silvia

    Leaf phenology refers to the timing of leaf life cycle events and is essential to our understanding of the earth system as it impacts the terrestrial carbon and water cycles and indirectly global climate through changes in surface roughness and albedo. Traditionally, leaf phenology is described as a response to higher temperatures in spring and lower temperatures in autumn for temperate regions. With the advent of carbon ecosystem models however, we need a better representation of seasonal cycles, one that is able to explain phenology in different areas around the globe, including tropical regions, and has the capacity to predict phenology under future climates. We propose a global phenology model based on the hypothesis that phenology is a strategy through which plants reach optimal carbon assimilation. We fit this 14 parameter model to five years of space borne data of leaf area index using a Bayesian fitting algorithm and we use it to simulate leaf seasonal cycles across the globe. We explain the observed increase in leaf area over the Amazon basin during the dry season through an increase in available direct solar radiation. Seasonal cycles in dry tropical areas are explained by the variation in water availability, while phenology at higher latitudes is driven by changes in temperature and daylength. We explore the hypothesis that phenological traits can be explained at the biome (plant functional group) level and we show that some characteristics can only be explained at the species level due to local factors such as water and nutrient availability. We anticipate that our work can be incorporated into larger earth system models and used to predict future phenological patterns..

  13. Generality of leaf trait relationships: A test across six biomes

    SciTech Connect

    Reich, P.B.; Ellsworth, D.S.; Walters, M.B.; Vose, J.M.; Gresham, C.; Volin, J.C.; Bowman, W.D. |

    1999-09-01

    Convergence in interspecific leaf trait relationships across diverse taxonomic groups and biomes would have important evolutionary and ecological implications. Such convergence has been hypothesized to result from trade-offs that limit the combination of plant traits for any species. Here the authors address this issue by testing for biome differences in the slope and intercept of interspecific relationships among leaf traits: longevity, net photosynthetic capacity (A{sub max}), leaf diffusive conductance (G{sub S}), specific leaf area (SLA), and nitrogen (N) status, for more than 100 species in six distinct biomes of the Americas. The six biomes were: alpine tundra-subalpine forest ecotone, cold temperate forest-prairie ecotone, montane cool temperate forest, desert shrubland, subtropical forest, and tropical rain forest. Despite large differences in climate and evolutionary history, in all biomes mass-based leaf N (N{sub mass}), SLA, G{sub S}, and A{sub max} were positively related to one another and decreased with increasing leaf life span. The relationships between pairs of leaf traits exhibited similar slopes among biomes, suggesting a predictable set of scaling relationships among key leaf morphological, chemical, and metabolic traits that are replicated globally among terrestrial ecosystems regardless of biome or vegetation type. However, the intercept (i.e., the overall elevation of regression lines) of relationships between pairs of leaf traits usually differed among biomes. With increasing aridity across sites, species had greater A{sub max} for a given level of G{sub S} and lower SLA for any given leaf life span. Using principal components analysis, most variation among species was explained by an axis related to mass-based leaf traits (A{sub max}, N, and SLA) while a second axis reflected climate, G{sub S}, and other area-based leaf traits.

  14. Leaf Phenology of Amazonian Canopy Trees as Revealed by Spectral and Physiochemical Measurements

    NASA Astrophysics Data System (ADS)

    Chavana-Bryant, C.; Gerard, F. F.; Malhi, Y.; Enquist, B. J.; Asner, G. P.

    2013-12-01

    The phenological dynamics of terrestrial ecosystems reflect the response of the Earth's biosphere to inter- and intra-annual dynamics of climatic and hydrological regimes. Some Dynamic Global Vegetation Models (GDVMs) have predicted that by 2050 the Amazon rainforest will begin to dieback (Cox et al. 2000, Nature) or that the ecosystem will become unsustainable (Salazar et al. 2007, GRL). One major component in DGVMs is the simulation of vegetation phenology, however, modelers are challenged with the estimation of tropical phenology which is highly complex. Current modeled phenology is based on observations of temperate vegetation and accurate representation of tropical phenology is long overdue. Remote sensing (RS) data are a key tool in monitoring vegetation dynamics at regional and global scales. Of the many RS techniques available, time-series analysis of vegetation indices (VIs) has become the most common approach in monitoring vegetation phenology (Samanta et al. 2010, GRL; Bradley et al. 2011, GCB). Our research focuses on investigating the influence that age related variation in the spectral reflectance and physiochemical properties of leaves may have on VIs of tropical canopies. In order to do this, we collected a unique leaf and canopy phenological dataset at two different Amazonian sites: Inselberg, French Guyana (FG) and Tambopata, Peru (PE). Hyperspectral reflectance measurements were collected from 4,102 individual leaves sampled to represent different leaf ages and vertical canopy positions (top, mid and low canopy) from 20 different canopy tree species (8 in FG and 12 in PE). These leaf spectra were complemented with 1) leaf physical measurements: fresh and dry weight, area and thickness, LMA and LWC and 2) leaf chemical measurements: %N, %C, %P, C:N and d13C. Canopy level observations included top-of-canopy reflectance measurements obtained using a multispectral 16-band radiometer, leaf demography (tot. number and age distribution) and branch

  15. 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

  16. 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

  17. Leaf Phenological Characters of Main Tree Species in Urban Forest of Shenyang

    PubMed Central

    Xu, Sheng; Xu, Wenduo; Chen, Wei; He, Xingyuan; Huang, Yanqing; Wen, Hua

    2014-01-01

    Background Plant leaves, as the main photosynthetic organs and the high energy converters among primary producers in terrestrial ecosystems, have attracted significant research attention. Leaf lifespan is an adaptive characteristic formed by plants to obtain the maximum carbon in the long-term adaption process. It determines important functional and structural characteristics exhibited in the environmental adaptation of plants. However, the leaf lifespan and leaf characteristics of urban forests were not studied up to now. Methods By using statistic, linear regression methods and correlation analysis, leaf phenological characters of main tree species in urban forest of Shenyang were observed for five years to obtain the leafing phenology (including leafing start time, end time, and duration), defoliating phenology (including defoliation start time, end time, and duration), and the leaf lifespan of the main tree species. Moreover, the relationships between temperature and leafing phenology, defoliating phenology, and leaf lifespan were analyzed. Findings The timing of leafing differed greatly among species. The early leafing species would have relatively early end of leafing; the longer it took to the end of leafing would have a later time of completed leafing. The timing of defoliation among different species varied significantly, the early defoliation species would have relatively longer duration of defoliation. If the mean temperature rise for 1°C in spring, the time of leafing would experience 5 days earlier in spring. If the mean temperature decline for 1°C, the time of defoliation would experience 3 days delay in autumn. Interpretation There is significant correlation between leaf longevity and the time of leafing and defoliation. According to correlation analysis and regression analysis, there is significant correlation between temperature and leafing and defoliation phenology. Early leafing species would have a longer life span and consequently have

  18. 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

  19. Variations in leaf morphometry and nitrogen concentration in Betula pendula Roth., Corylus avellana L. and Lonicera xylosteum L.

    PubMed

    Kull, O; Niinemets, U

    1993-04-01

    Relations between leaf dry weight to leaf area (LWA), leaf nitrogen concentration and irradiance inside a natural canopy were studied in Betula pendula Roth., Corylus avellana L. and Lonicera xylosteum L. In all species, LWA increased with increasing irradiance. Relative variability in LWA was smaller in Betula pendula than in the other two species. In Corylus avellana, LWA also depended on total plant height. Foliar nitrogen concentration (on a dry weight basis) increased with increasing irradiance and LWA in Betula pendula, but decreased in the other two species. The interspecific variation in response to light availability and in nitrogen partitioning may be caused by different light demands or different life forms (trees versus shrubs), or both, of the species examined, and must be considered in contemporary canopy models. PMID:14969921

  20. 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

  1. 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.

  2. Speculations on the origin of life and thermophily: Review of available information on reverse gyrase suggests that hyperthermophilic procaryotes are not so primitive

    NASA Astrophysics Data System (ADS)

    Forterre, Patrick; Confalonier, Fabrice; Charbonnier, Franck; Duguet, Michel

    1995-06-01

    All present-day hyperthermophiles studied so far (eitherBacteria orArchaea) contain a unique DNA topoisomerase, reverse gyrase, which probably helps to stabilize genomic DNA at high temperature. Herein the data relating this enzyme is reviewed and discussed from the perspective of the nature of the last detectable common ancestor and the origin of life. The sequence of the gene encoding reverse gyrase from an archaeon,Sulfolobus acidocaldarius, suggests that this enzyme contains both a helicase and a topoisomerase domains (Confalonieriet al.,Proc. Natl. Acad. Sci., 1993, 90, 4735). Accordingly, it has been proposed that reverse gyrase originated by the fusion of DNA helicase and DNA topoisomerase genes. If reverse gyrase is essential for life at high temperature, its composite structure suggests that DNA helicases and topoisomerases appeared independently and first evolved in a mesophilic world. Such scenario contradicts the hypothesis that a direct link connects present day hyperthermophiles to a hot origin of life. We discuss different patterns for the early cellular evolution in which reverse gyrase appeared either before the emergence of the last common ancestor ofArchaea, Bacteria andEucarya, or in a lineage common to the two procaryotic domains. The latter scenario could explain why all today hyperthermophiles are procaryotes.

  3. 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.

  4. 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

  5. Vertical leaf pressure filter LVAzh 225

    SciTech Connect

    Fomichev, V.I.; Abramov, V.P.; Gutin, Y.V.

    1984-01-01

    A new vertical lead pressure filter LVAzh 225 has been developed with an arrangement for hydraulic coke removal. Industrial trials of the filter, however, showed the service life of the rubber seals of the butterfly valves to be short, so that butterfly valves were replaced by shut-off valves with a pneumatic drive. The prototype of the LVAzh 225 leaf filter has been recommended for series production.

  6. End-of-Life and Palliative Care for People with Intellectual Disabilities Who Have Cancer or Other Life-Limiting Illness: A Review of the Literature and Available Resources

    ERIC Educational Resources Information Center

    Tuffrey-Wijne, Irene; Hogg, James; Curfs, Leopold

    2007-01-01

    Background: As patterns of morbidity and mortality are changing, more people with intellectual disabilities develop cancer or other life-limiting illness. This paper reviews the literature around the need of people with intellectual disabilities for palliative care. Methods: A range of databases and the World Wide Web were searched for relevant…

  7. [Not Available].

    PubMed

    Frenette, Marjolaine; Saint-Arnaud, Jocelyne

    2016-03-01

    Different care settings in Quebec use levels of medical intervention forms, also called levels of care (LOC), to determine the code status of patients and to improve end-of-life care planning. It is not currently possible to know whether the levels of care in hospitals benefit patients and staff in facilitating the decision making process of treatment options and resuscitation measures. No study, to the best of the authors' knowledge, has been published about LOC, particularly in Quebec and Canada. This literature review was undertaken on levels of care in order to clarify this topic. Relevant articles are discussed under different themes that are pertinent to LOC. The themes addressed in this article include care at the end of life, do-not-resuscitate orders, treatment withdrawal, and decision making at end of life. PMID:26880120

  8. [Not Available].

    PubMed

    Pinzón Marín, Inés Yohanna; Rueda Barrera, Eduardo; Mejía Patiño, Omar A

    2015-01-01

    This article will present some of the arguments that have been exposed about the legal acceptability in the technique of gestation of human life by surrogacy, beginning for establish the multiple denominations that have been realized and which make know this technique as: surrogacy, surrogate motherhood or substitute motherhood. Then it will determine the legal aspects involved in the transit of this technique to its accomplishment through contracts, thereby specifying the essential elements (capacity, consent, cause and lawful purpose), the content and the possible manner of gestation human life contracts by surrogacy. PMID:27311158

  9. [Not Available].

    PubMed

    Bühlmann Lerjen, Eva; Hübbert, Laila; Papakonstantinou, Antroula; Hedayati, Elham; Linde, Cecilia; Månsson Broberg, Agneta

    2016-01-01

    Modern cancer therapy has noticeably improved the prognosis for various cancer diseases, but cardiovascular side effects are not uncommon, both in short and long term. The individual patient's cardiovascular risk profile affects the risk of developing side effects. Potential underestimation of this risk can lead to life-long severe cardiac disease for a patient that has been cured from cancer. Overestimation of the risk can lead to withdrawal of life-saving cancer treatment because of potentially reversible or mild cardiac side effects. A multidisciplinary approach will lead to better handling of cardio-oncologic patients. PMID:27299327

  10. 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...

  11. 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…

  12. 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...

  13. 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).

  14. Optimal leaf water use drives ecosystem water and carbon fluxes in a changing environment

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Canopy water and carbon exchange rates are controlled by leaf-level adjustment of stomatal aperture and photosynthetic capacity. Both leaf-level stomatal conductance and the leaf photosynthetic machinery respond nonlinearly to soil water availability, atmospheric CO2 concentration, and other environ...

  15. Human Ebola virus infection in West Africa: a review of available therapeutic agents that target different steps of the life cycle of Ebola virus.

    PubMed

    Lai, Kang Yiu; Ng, Wing Yiu George; Cheng, Fan Fanny

    2014-01-01

    The recent outbreak of the human Zaire ebolavirus (EBOV) epidemic is spiraling out of control in West Africa. Human EBOV hemorrhagic fever has a case fatality rate of up to 90%. The EBOV is classified as a biosafety level 4 pathogen and is considered a category A agent of bioterrorism by Centers for Disease Control and Prevention, with no approved therapies and vaccines available for its treatment apart from supportive care. Although several promising therapeutic agents and vaccines against EBOV are undergoing the Phase I human trial, the current epidemic might be outpacing the speed at which drugs and vaccines can be produced. Like all viruses, the EBOV largely relies on host cell factors and physiological processes for its entry, replication, and egress. We have reviewed currently available therapeutic agents that have been shown to be effective in suppressing the proliferation of the EBOV in cell cultures or animal studies. Most of the therapeutic agents in this review are directed against non-mutable targets of the host, which is independent of viral mutation. These medications are approved by the Food and Drug Administration (FDA) for the treatment of other diseases. They are available and stockpileable for immediate use. They may also have a complementary role to those therapeutic agents under development that are directed against the mutable targets of the EBOV. PMID:25699183

  16. [A inversion model for remote sensing of leaf water content based on the leaf optical property].

    PubMed

    Fang, Mei-hong; Ju, Wei-min

    2015-01-01

    Leaf water content is a fundamental physiological characteristic parameter of crops, and plays an important role in the study of the ecological environment. The aim of the work reported in this paper was to focus upon the retrieval of leaf water content from leaf-scale reflectance spectra by developing a physical inversion model based on the radiative transfer theory and wavelet analysis techniques. A continuous wavelet transform was performed on each of leaf component specific absorption coefficients to pick wavelet coefficients that were identified as highly sensitive to leaf water content and insensitive to other components. In the present study, for identifying the most appropriate wavelet, the six frequently used wavelet functions available within MATLAB were tested. Two biorl. 5 wavelet coefficients observed at the scale of 200 nm are provided with good performance, their wave-length positions are located at 1 405 and 1 488 nm, respectively. Two factors (α and Δ) of the predictive theoretical models based on the biorl. 5 wavelet coefficients of the leaf-scale reflectance spectra were determined by leaf structure parameter N. We built a database composed of thousands of simulated leaf reflectance spectra with the PROSPECT model. The entire dataset was split into two parts, with 60% the calibration subset assigned to calibrating two factors (α and Δ) of the predictive theoretical model. The remaining 40% the validation subset combined with the LOPEX93 experimental dataset used for validating the models. The results showed that the accuracy of the models compare to the statistical regression models derived from the traditional vegetation indices has improved with the highest predictive coefficient of determination (R2) of 0. 987, and the model becomes more robust. This study presented that wavelet analysis has the potential to capture much more of the information contained with reflectance spectra than previous analytical approaches which have tended to

  17. Influence of Vegetation Structure on Lidar-derived Canopy Height and Fractional Cover in Forested Riparian Buffers During Leaf-Off and Leaf-On Conditions

    PubMed Central

    Wasser, Leah; Day, Rick; Chasmer, Laura; Taylor, Alan

    2013-01-01

    Estimates of canopy height (H) and fractional canopy cover (FC) derived from lidar data collected during leaf-on and leaf-off conditions are compared with field measurements from 80 forested riparian buffer plots. The purpose is to determine if existing lidar data flown in leaf-off conditions for applications such as terrain mapping can effectively estimate forested riparian buffer H and FC within a range of riparian vegetation types. Results illustrate that: 1) leaf-off and leaf-on lidar percentile estimates are similar to measured heights in all plots except those dominated by deciduous compound-leaved trees where lidar underestimates H during leaf off periods; 2) canopy height models (CHMs) underestimate H by a larger margin compared to percentile methods and are influenced by vegetation type (conifer needle, deciduous simple leaf or deciduous compound leaf) and canopy height variability, 3) lidar estimates of FC are within 10% of plot measurements during leaf-on periods, but are underestimated during leaf-off periods except in mixed and conifer plots; and 4) depth of laser pulse penetration lower in the canopy is more variable compared to top of the canopy penetration which may influence within canopy vegetation structure estimates. This study demonstrates that leaf-off lidar data can be used to estimate forested riparian buffer canopy height within diverse vegetation conditions and fractional canopy cover within mixed and conifer forests when leaf-on lidar data are not available. PMID:23382966

  18. [Not Available].

    PubMed

    Trochu, Jean-Noël

    2014-10-01

    The World Health Organization defines Quality of life (QOL) as an individual's perception of their position in lfe in the context of the culture and value systems in which they live and in relation to their goals, expectations, standards and concerns. During chronic heart failure several factors contribute to the alteration of QOL: congestion, dyspnea, fatigue, sleep disturbances, anxiety, depression, side effects of medications, impacts on personal life and disruption of social interactions which can modify patients' social roles, life situation and ability to travel. NYHA class, exercise tolerance represent physician-reported patient well-being parameters but do not actually assess alterations expressed by the patient. There are several specific instruments to better evaluate QOL: they can be generic (self-assessment of general well-being), health related QOL (SF36), specific to diseases (Minnesota Living With Heart Failure Questionnaire) or domain specific (anxiety, depression). Impact of ACE inhibitors, angiotensin 2 antagonists, and beta-blockers are small while that of cardiac resynchronization and multidisciplinary management programmes are more efficient. In advanced heart failure when patient recognize equal importance between improvement in QOL and gain in survival, left ventricle assist devices (LVAD) significantly improve QOL at early (3 months) and long-term (2 years) follow up. LVADs allow the rapid return of the patients at home and genuine autonomy in the context of a personalized care plan supervised by the referring centre. Beneficial effects are close to those of heart transplantation but still are limited by the need of taking care of their equipment. PMID:27120907

  19. Leaf nitrate assimilation during leaf expansion period: comparison of temperate and boreal tree species

    NASA Astrophysics Data System (ADS)

    Koyama, L.; Tokuchi, N.; Kielland, K.

    2011-12-01

    We examined nitrate assimilation in several tree species to test the hypothesis that plant N acquisition is highest in early spring due to the N demands of leaf growth and the seasonal availability of soil N. Specifically, we advance the idea that trees acquire N most actively during the leaf expansion period, which serves to offset growth-dilution of foliar N. However, it has been observed that boreal species expand their leaves more rapidly than do temperate species, suggesting that they exhibit a different seasonal pattern of N acquisition than do temperate species. To examine these relationships we measured leaf nitrate reductase activity (NRA) as a proxy for nitrate assimilation, leaf expansion rates, and foliar N concentrations on three boreal tree species and three temperate tree species throughout their leaf expansion period. An evergreen species (Quercus glauca) and two deciduous species (Acer palmatum and Zelkova serrata) were investigated in temperate Japan, and three deciduous species Alnus crispa, Betula papyrifera and Populus tremuloides were chosen in a boreal forest in interior Alaska, US. The patterns of foliar N concentrations were very similar across all six species, but the mean leaf expansion period was shorter in the boreal species (about 25 days) than in temperate species (about 29 days). All temperate species showed clear peaks of leaf NRA in the middle of leaf expansion period, suggesting that leaves partly compensate for the N dilution during expansion via foliar nitrate assimilation, and that plant nitrate acquisition was effectively timed to coincide with soil N availability generally increased in early spring. By contrast, peak NRA in the boreal species were observed in different stage of leaf expansion, but as in the temperate species declined to very low levels after the leaves were fully expanded. Our results demonstrate that plant nitrate assimilation is concentrated during leaf expansion in spring and early summer, but declines to

  20. [Not Available].

    PubMed

    Schilter, T

    1998-01-01

    The euthanasia action in Nazi Germany during 1940/41 ("Aktion T4") belongs to the most horrible chapters in history of medicine. The article describes the life of Horst Schumann, who was involved in the murder of more than 15 000 people and after that did cruel sterilization experiments in Auschwitz. It will be depicted the personal characteristics to show, why he was susceptible to this development. The critical look at these events shall warn us not to push away mental patients and mentally handicapped people from our society. The personal rights of this group of patients must not be questioned. PMID:11619921

  1. [Not Available].

    PubMed

    Eskenazi, J

    1970-01-01

    Based on hardly accessible archive documents as well as other original sources and literature data, the author traces the life of the Russian physician K. Yuriev, and more particularly the years of his sojourn in Bulgaria. The emigrant-populist has merits towards Bulgarian surgery in the period of antisepsis. Dr. Yuriev was in contact with the leftists of the liberal party, led by Zahari Stoyanov, he was in charge of the Russe revolutionary circle "1st March", a good friend to the well known Bulgarian populist Spiro Gulabchev and to the outstanding Bulgarian physician Dr. Paraskev Stoyanov. PMID:11636533

  2. 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.

  3. [Not Available].

    PubMed

    Cederholm, Tommy; Hellénius, Mai-Lis

    2016-01-01

    By the food intake man is daily exposed to numerous chemical agents with impact on ageing and longevity. Over the last two centuries longevity in the affluent societies has increased by 2 years per decade. Improved food habits are important contributing factors.  Dietary patterns of populations with long life-spans, like the traditional Mediterranean diet and the Okinawa Island diet, provide the basis to recommend plant foods like vegetables, legumes, fruits, non-tropical vegetable oils as basic fat, light meat (e.g. poultry) of moderate amounts, plenty of fish and moderate beverage intakes of wine, coffee and tea. Oxidative damage is suggested as one major reason for exaggerated ageing. Foods that promote longevity are rich in antioxidants. Still there is no evidence that extra anti-oxidant supplementation has any beneficial effects. Energy balance to avoid obesity at young and middle ages, e.g. by calorie restricted diets and increased physical activity, promotes longevity, whereas at older age overweight is usually associated with a longer life-span. PMID:27272545

  4. The oxygen isotope enrichment of leaf-exported assimilates – does it always reflect lamina leaf water enrichment?

    PubMed Central

    Gessler, Arthur; Brandes, Elke; Keitel, Claudia; Boda, Sonja; Kayler, Zachary E; Granier, André; Barbour, Margaret; Farquhar, Graham D; Treydte, Kerstin

    2013-01-01

    The oxygen stable isotope composition of plant organic matter (OM) (particularly of wood and cellulose in the tree ring archive) is valuable in studies of plant–climate interaction, but there is a lack of information on the transfer of the isotope signal from the leaf to heterotrophic tissues. We studied the oxygen isotopic composition and its enrichment above source water of leaf water over diel courses in five tree species covering a broad range of life forms. We tracked the transfer of the isotopic signal to leaf water-soluble OM and further to phloem-transported OM. Observed leaf water evaporative enrichment was consistent with values predicted from mechanistic models taking into account nonsteady-state conditions. While leaf water-soluble OM showed the expected 18O enrichment in all species, phloem sugars were less enriched than expected from leaf water enrichment in Scots pine (Pinus sylvestris), European larch (Larix decidua) and Alpine ash (Eucalyptus delegatensis). Oxygen atom exchange with nonenriched water during phloem loading and transport, as well as a significant contribution of assimilates from bark photosynthesis, can explain these phloem 18O enrichment patterns. Our results indicate species-specific uncoupling between the leaf water and the OM oxygen isotope signal, which is important for the interpretation of tree ring data. PMID:23763637

  5. [Not Available].

    PubMed

    Shingarov, G H

    1970-01-01

    In this paper some of the philosophical problems of the history of neurophysiology are discussed, paying special attention to the credit going to Hegel, Rene Decart, to the Russian materialistic school, led by I. P. Pavlov and others. Of particular interest is the interpretation of the following problems: the historical consistency of the appearance of the basic conceptions with which the pre-Pavlov neurophysiology was chiefly concerned, the logical subordination of its categories and ideas, the creation of the basic concepts in the study of the higher nervous activity by I. P. Pavlov, their logical and practical substantiation and the like. An attempt is made, proceeding from dialectic materialism positions, for interpretation of the problems posed, which are of paramount theoretic and practical importance for science and life. PMID:11636540

  6. [Not Available].

    PubMed

    Gillberg, Christopher

    Co-existence of attention-deficit/hyperactivity disorder, oppositional defiant disorder, tic disorders, developmental coordination disorder, language disorder, learning problems, and autism spectrum disorder and sharing of symptoms across disorders, contribute to the typical clinical presentation in child psychiatry as well as in developmen-tal medicine. The acronym ESSENCE refers to Early Symptomatic Syndromes Eliciting Neurodevelopmental Clinical Examinations. Affected children are brought for clinical assessment because of impairing symptoms that raise concern before the age of about 5 years in general development, communication and language, social inter-relatedness, motor coordination, attention, activity, behaviour, mood, and/or sleep. Such children are usually in need of a range of expert assessments, but a holistic approach is rarely taken from the start. Major problems in at least one ESSENCE domain before 5 years of age predict poor mental health later in life. Expert ESSENCE centres for assessment, habilitation and treatment of these children are needed. PMID:25584597

  7. [Not Available].

    PubMed

    Wallach, Isabelle; Ducandas, Xuân; Martel, Michel; Thomas, Réjean

    2016-03-01

    This research examines obstacles faced by older people living with HIV in maintaining their significant social ties (family, friends) in the light of a double theoretical framework, inter-sectionality and the course of life. Favoring a qualitative methodology, this research is based on in-depth, semi-directed interviews with a diverse sample of 38 people living with HIV, aged 50-73 years. Analysis reveals that a significant proportion of participants have experienced ruptures or deterioration of close ties with intimates at the level of family or friends. The principal factors behind these difficulties are the past and present stigma associated with HIV and /or other social positions, long-term effects of HIV, issues related to aging and crosscutting effects of HIV and aging. PMID:26934548

  8. [Not Available].

    PubMed

    Sala, G

    1993-01-01

    Along the 5000 years of human history, medicine and doctors are always present in all epochs and in all civilizations. In the early millinariums the doctor swings from magic to science; even nowadays supranatural and theurgic influences are present in some medical acts. In the IV century B.C. Hippocrates found medicine on observation and on reason; experimental method starts, yet with the limits given by rudimental techniques and the limitations bound to dogmatism and authority. From the XVII century on empirism replaces with difficulty metaphysics and induction substitutes deduction. In the XX century hypothetic-deductive, both based on the formulation of checked facts (C. Bernard) and on the presentation of fanciful hypotheses (K. Popper), characterizes the actual development of science and of medicine. Nowadays artificial intelligence expands the complex systems of life and of disease: the scientific aspects, moreover, are integrated with humanistic features and with environmental requirements. PMID:11640616

  9. [Not Available].

    PubMed

    Svensson, Mikael; Nilsson, Fredrik

    2016-01-01

    The Swedish Dental and Pharmaceutical Benefits Agency (TLV) is the government body responsible for deciding whether outpatient drugs are to be included in the pharmaceutical benefits scheme. This paper analyzed all decisions made by TLV between 2005 and 2011 in order to investigate how the cost-effectiveness of a drug and the severity of the disease the drug targets affected the likelihood of subsidy of a drug. We find that TLV places significant weight on both the cost-effectiveness, measured as the cost per Quality-Adjusted Life Year (QALY), and disease severity. We also find that the higher cost per QALY approved for severe diseases is mainly represented by cancer drugs. Drugs targeting severe diseases other than cancer have a similar cost per QALY as for non-severe diseases. PMID:27404777

  10. [Not Available].

    PubMed

    Perrotta, F M; Lubrano, E

    2016-01-01

    Psoriatic arthritis (PsA) is a chronic inflammatory disease that possibly leads to structural damage and to a reduction of joint function and poor quality of life. Treatment of PsA has changed since its introduction of anti- TNF drugs, which have shown to reduce the symptoms and signs of the disease and slow the radiographic progression. However, recently, the discovery of new pathogenic mechanisms have made possible the development of new molecules that target pro-inflammatory cytokines involved in skin, joint and entheseal inflammation. New drugs like ustekinumab, secukinumab and apremilast inhibit interleukin axis and intracellular pathways and showed their efficacy and safety in randomized clinical trials. These drugs have been recently approved for the treatment of PsA and included in the new EULAR and GRAPPA treatment recommendations. The aim of this paper is to briefly review the clinical trials that led to their approval for PsA. PMID:27608793

  11. [Not Available].

    PubMed

    Lévy, Joseph; Dumas, Jean; Thoër, Christine; Ryan, Bill; Léobon, Alain

    2010-02-16

    A large number of organizations working with LGBT minorities are currently in the process of developing websites and using online intervention strategies with a view to providing information, promoting prevention and improving healthcare and quality of life. This paper outlines the findings of a study conducted among organizations that responded to a survey on their internet activities and interventions, and aims to provide a national Canadian profile of the field. The results of this survey highlight the many advantages which community organizations tend to associate with this type of intervention. But they also underline the constraints which such organizations face and the difficulties that may arise as a result of developing online interventions. PMID:20441638

  12. Antimicrobial Compounds from Leaf Extracts of Jatropha curcas, Psidium guajava, and Andrographis paniculata

    PubMed Central

    Rahman, M. M.; Ahmad, S. H.; Mohamed, M. T. M.; Ab Rahman, M. Z.

    2014-01-01

    The present research was conducted to discover antimicrobial compounds in methanolic leaf extracts of Jatropha curcas and Andrographis paniculata and ethanolic leaf extract of Psidium guajava and the effectiveness against microbes on flower preservative solution of cut Mokara Red orchid flowers was evaluated. The leaves were analyzed using gas chromatography-mass spectrometry. A total of nine, 66, and 29 compounds were identified in J. curcas, P. guajava, and A. paniculata leaf extracts, with five (88.18%), four (34.66%), and three (50.47%) having unique antimicrobial compounds, respectively. The experimental design on vase life was conducted using a completely randomized design with 10 replications. The flower vase life was about 6 days in the solution containing the P. guajava and A. paniculata leaf extracts at 15mg/L. Moreover, solution with leaf extracts of A. paniculata had the lowest bacterial count compared to P. guajava and J. curcas. Thus, these leaf extracts revealed the presence of relevant antimicrobial compounds. The leaf extracts have the potential as a cut flower solution to minimize microbial populations and extend flower vase life. However, the activities of specific antimicrobial compounds and double or triple combination leaf extracts to enhance the effectiveness to extend the vase life need to be tested. PMID:25250382

  13. Leaf endophyte load influences fungal garden development in leaf-cutting ants

    PubMed Central

    2012-01-01

    Background Previous work has shown that leaf-cutting ants prefer to cut leaf material with relatively low fungal endophyte content. This 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 their host plants’ defense against leaf-cutting ants. To measure the long-term cost to the ant colony of fungal endophytes in their forage material, we conducted a 20-week laboratory experiment to measure fungal garden development for colonies that foraged on leaves with low or high endophyte content. Results Colony mass and the fungal garden dry mass did not differ significantly between the low and high endophyte feeding treatments. There was, however, a marginally significant trend toward greater mass of fungal garden per ant worker in the low relative to the high endophyte treatment. This trend was driven by differences in the fungal garden mass per worker from the earliest samples, when leaf-cutting ants had been foraging on low or high endophyte leaf material for only 2 weeks. At two weeks of foraging, the mean fungal garden mass per worker was 77% greater for colonies foraging on leaves with low relative to high endophyte loads. Conclusions Our data suggest that the cost of endophyte presence in ant forage material may be greatest to fungal colony development in its earliest stages, when there are few workers available to forage and to clean leaf material. This coincides with a period of high mortality for incipient colonies in the field. We discuss how the endophyte-leaf-cutter ant interaction may parallel constitutive defenses in plants, whereby endophytes reduce the rate of colony development when its risk of mortality is greatest. PMID:23140096

  14. [Not Available].

    PubMed

    Jacqueline, Sophie; Bleton, Jean; Huynh-Charlier, Isabelle; Minchin, Sébastien; Muller, Anne-Laure; Poupon, Joël; Charlier, Philippe

    2016-01-01

    Today, the development of analytic methods brings new scientific insights into the research on the mummification process used by embalmers in ancient Egypt. The application of these techniques of molecular analysis, elementary analysis, botanical analysis and bibliographic analysis of ancient texts allows us to know the composition of mummification balms and material involved in the conservation of the body. Such substances, which are mineral, animal or plant material, played a practical and a symbolic part in the composition of balms used for the preservation of mummified bodies and therefore in the passage to the eternal life after the death. The comparison of analysis results can inform us about changes in embalming techniques depending of the time, the place of mummification, the deceased's social status. However the number of mummies studied is very small compared to the number of bodies that were mummified. Finally the techniques of mummification and making balms were very variable according to practitioners and their modus operandi. Today, using these technic of chemical analysis and medical imaging techniques, we can authenticate and reconstruct the history of museum pieces, as we have done in the unpublished studies conducted in support of literature data previously collected. PMID:27349124

  15. [Not Available].

    PubMed

    Wekell, Per; Karlsson, Anna; Fasth, Anders; Berg, Stefan

    2016-01-01

    Familial Mediterranean fever - an important disease in a globalised world Familial Mediterranean fever (FMF) is characterized by recurrent febrile attacks during 1/2-3 days associated with peritonitis, pleuritis and arthritis. FMF is the most common monogenic autoinflammatory disease in the world, with over 100 000 affected individuals. It is particularly common in individuals with an origin in the eastern Mediterranean Basin, where the disease has a prevalence of 100-200 per 100 000. The gene for FMF (MEFV) was identified in 1997 with an autosomal recessive inheritance; however, a significant proportion (≈25%) of clinical patients lack two mutations. MEFV codes for the protein pyrin, whose exact function still needs to be defined. The most serious complication of FMF is amyloid A amyloidosis, in particular renal amyloidosis. FMF is efficiently treated with daily doses of colchicine resulting in an almost normal life expectancy and amyloidosis confined to non-compliant patients. In today's globalized world we need to adapt to a new context that includes inherited conditions, which have historically been uncommon in our part of the world. One of these conditions is FMF, that should primarily be suspected in individuals with an origin in the eastern Mediterranean Basin and recurrent attacks of fever. PMID:27551868

  16. [Not Available].

    PubMed

    Ulisubisya, Mpoki; Dahlén, Erik; Jörnvall, Henrik; Irestedt, Lars; Baker, Tim

    2016-01-01

    The impact of an Anaesthesia and Intensive Care collaboration between Sweden and Tanzania Anaesthesia and intensive care is a neglected specialty in low-income countries. Many countries have less than 1 anaesthesia provider per 100,000 population and few hospitals in Africa have the resources for managing critically ill patients. Health partnerships between institutions in high- and low-income countries have been proposed as an effective way to strengthen health systems. This article describes a partnership in anaesthesia and intensive care between institutions in Sweden and Tanzania and its impact at regional and national levels. The partnership, initiated in 2008 on the request of Muhimbili National Hospital in Dar es Salaam, conducts training, exchanges, research, equipment, routines and guidelines projects. Through the newly formed Life Support Foundation, the partnership has expanded to all hospitals in Dar es Salaam, has assisted in the reactivation of the Society of Anaesthesiologists of Tanzania and has seen a marked increase in the number of trainee doctors. PMID:27622761

  17. [Not Available].

    PubMed

    Pecevski, Dejan; Natschläger, Thomas; Schuch, Klaus

    2009-01-01

    The Parallel Circuit SIMulator (PCSIM) is a software package for simulation of neural circuits. It is primarily designed for distributed simulation of large scale networks of spiking point neurons. Although its computational core is written in C++, PCSIM's primary interface is implemented in the Python programming language, which is a powerful programming environment and allows the user to easily integrate the neural circuit simulator with data analysis and visualization tools to manage the full neural modeling life cycle. The main focus of this paper is to describe PCSIM's full integration into Python and the benefits thereof. In particular we will investigate how the automatically generated bidirectional interface and PCSIM's object-oriented modular framework enable the user to adopt a hybrid modeling approach: using and extending PCSIM's functionality either employing pure Python or C++ and thus combining the advantages of both worlds. Furthermore, we describe several supplementary PCSIM packages written in pure Python and tailored towards setting up and analyzing neural simulations. PMID:19543450

  18. [Not Available].

    PubMed

    Meszaros, J

    1999-01-01

    By the end of World War I the Hungarian Psychoanalytic movement was strong and deeply integrated into the cultural and intellectual life of Budapest. The city was ready to be the center of the European psychoanalysis. The paper discusses how Budapest lost its growing eminence as a center, but because of the political-social changes in Hungary in the years 1918-1920. The paper will examine the two waves of Hungarian emigration between the world wars, the first in the early twenties to the Weimar Republic, and then in the thirties, to the United States and Australia. These movements of important Hungarian psychoanalysts, account both becoming weaker of the Budapest School and at the same time its influence in other countries. The author highlights the outstanding role of the American Psychoanalytic Association's setting up the Emergency Committee on Relief and Immigration in saving the lives of many European colleagues. America was open to European psychoanalysis at that time and in return immigrants facilitated the development of modern psychotherapy and psychoanalysis. The influence of Vienna, Budapest and Berlin can be traced in contemporary psychoanalytic culture in the United States. The documentation for this paper was researched in Washington, D.C., New York and London, supported by fellowships and grants from the Woodrow Wilson International Center and the Soros Foundation. PMID:11638925

  19. [Not Available].

    PubMed

    Schott, Heinz

    2014-01-01

    Viktor von Weizsäcker (1886-1957) founded his concept of medical anthropology as a clinician educated in internal medicine and neurology. He tried to broaden natural scientific medicine psychosomatically focussing on the "sick human". The natural scientific approach would exclude subjectivity, and therefore he propagated the "introduction of the subject' (Einführung des Subjekts) into the life sciences. His own sensory physiological experiments and Sigmund Freud's psychoanalysis inspired him essentially since the 1920s. In his main work Der Gestaltkreis (gestalt circle) published in 1940 he stressed the "entity of perceiving and moving" (Einheit von Wahrnehmen und Bewegen) in regard to relevant aspects of medicine. In 1932, Weizsäcker became a member of the Heidelberg Academy of Sciences, whose president he was from 1947 till 1949; 1942 he became a member of the Leopoldina. Primarily his merits as a neurologist were highly appreciated. His medical anthropology was not relevant for his election by the two academies. Nevertheless, there was a certain repudiation against the objectivistic and materialistic Weltanschauung within the scientific community. So, Paracelsus and Goethe were highly estimated as natural philosophical guides for own conceptions. This was especially evident for the circle around Wilhelm Troll and Karl Lothar Wolf in Halle, both members of the Leopoldina, who were fascinated by Goethe's concept of "Gestalt". Weizsäcker's lecture on "Gestalt und Zeit" in Halle in 1942 fitted in the concept of those natural scientists. PMID:27514115

  20. [Not Available].

    PubMed

    Dussart, A; De Buyst, J; Djeunang, C; Janssens, M; Müller, M-F; Strebelle, E; Mathe, K; Infantino, S; Malfilâtre, G

    2016-01-01

    This is the clinical history of a term baby born at home who presents a severe hyperbilirubinémia. The medical monitoring was assessed by a private midwife according to parental choice. On the third day of life, the newborn presented an icterus and was exposed to natural daylight in the familial greenhouse under the midwife recommandations. On that day, no laboratory test precised the bilirubin level. On the fifth day, a blood sampling revealed a very high blood bilirubinémia (31 mg/dl or 527 mmol/L), the baby is refered to our NICU and underwent an exchange transfusion. The radiological assessment report structural abnomalies in basal ganglia seen on both MRI and transfontannellar echography. These lesions are known to be responsible of cerebral palsy and hearing loos. The neurophysiologic investigations showed background abnormaly and depression. The extensive blood sampling excluded haemolysis. The clinical examination brought out neurologic impairement and weight loos in this exclusively breastfed baby. This clinical case point out the increasing risk of home Kernicterius as hospital stays diminish and homebirth enthousiasm rise up. The present clinical situation vouches for an adaptation of care giving to both mother and child at home in order to avoid this severe illness. PMID:27120931

  1. 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...

  2. Autumn leaf subsidies influence spring dynamics of freshwater plankton communities.

    PubMed

    Fey, Samuel B; Mertens, Andrew N; Cottingham, Kathryn L

    2015-07-01

    While ecologists primarily focus on the immediate impact of ecological subsidies, understanding the importance of ecological subsidies requires quantifying the long-term temporal dynamics of subsidies on recipient ecosystems. Deciduous leaf litter transferred from terrestrial to aquatic ecosystems exerts both immediate and lasting effects on stream food webs. Recently, deciduous leaf additions have also been shown to be important subsidies for planktonic food webs in ponds during autumn; however, the inter-seasonal effects of autumn leaf subsidies on planktonic food webs have not been studied. We hypothesized that autumn leaf drop will affect the spring dynamics of freshwater pond food webs by altering the availability of resources, water transparency, and the metabolic state of ponds. We created leaf-added and no-leaf-added field mesocosms in autumn 2012, allowed mesocosms to ice-over for the winter, and began sampling the physical, chemical, and biological properties of mesocosms immediately following ice-off in spring 2013. At ice-off, leaf additions reduced dissolved oxygen, elevated total phosphorus concentrations and dissolved materials, and did not alter temperature or total nitrogen. These initial abiotic effects contributed to higher bacterial densities and lower chlorophyll concentrations, but by the end of spring, the abiotic environment, chlorophyll and bacterial densities converged. By contrast, zooplankton densities diverged between treatments during the spring, with leaf additions stimulating copepods but inhibiting cladocerans. We hypothesized that these differences between zooplankton orders resulted from resource shifts following leaf additions. These results suggest that leaf subsidies can alter both the short- and long-term dynamics of planktonic food webs, and highlight the importance of fully understanding how ecological subsidies are integrated into recipient food webs. PMID:25761444

  3. Do we Underestimate the Importance of Leaf Size in Plant Economics? Disproportional Scaling of Support Costs Within the Spectrum of Leaf Physiognomy

    PubMed Central

    Niinemets, Ülo; Portsmuth, Angelika; Tena, David; Tobias, Mari; Matesanz, Silvia; Valladares, Fernando

    2007-01-01

    Background Broad scaling relationships between leaf size and function do not take into account that leaves of different size may contain different fractions of support in petiole and mid-rib. Methods The fractions of leaf biomass in petiole, mid-rib and lamina, and the differences in chemistry and structure among mid-ribs, petioles and laminas were investigated in 122 species of contrasting leaf size, life form and climatic distribution to determine the extent to which differences in support modify whole-lamina and whole-leaf structural and chemical characteristics, and the extent to which size-dependent support investments are affected by plant life form and site climate. Key Results For the entire data set, leaf fresh mass varied over five orders of magnitude. The percentage of dry mass in mid-rib increased strongly with lamina size, reaching more than 40 % in the largest laminas. The whole-leaf percentage of mid-rib and petiole increased with leaf size, and the overall support investment was more than 60 % in the largest leaves. Fractional support investments were generally larger in herbaceous than in woody species and tended to be lower in Mediterranean than in cool temperate and tropical plants. Mid-ribs and petioles had lower N and C percentages, and lower dry to fresh mass ratio, but greater density (mass per unit volume) than laminas. N percentage of lamina without mid-rib was up to 40 % higher in the largest leaves than the total-lamina (lamina and mid-rib) N percentage, and up to 60 % higher than whole-leaf N percentage, while lamina density calculated without mid-rib was up to 80 % less than that with the mid-rib. For all leaf compartments, N percentage was negatively associated with density and dry to fresh mass ratio, while C percentage was positively linked to these characteristics, reflecting the overall inverse scaling between structural and physiological characteristics. However, the correlations between N and C percentages and structural

  4. Leaf growth pattern in evergreen and deciduous species of the Central Himalaya, India

    NASA Astrophysics Data System (ADS)

    Negi, G. C. S.; Singh, S. P.

    1992-12-01

    Leaf growth patterns were investigated in 11 evergreen (with leaf life-spans of just more than 1 year) and 15 deciduous species, occurring along an elevational gradient of 600-2200 m elevation in the Central Himalaya. Records were made of the leaf initiation period, leaf population dynamics, leaf expansion, leaf mass changes, leaf longevity and related parameters. Species of both groups produced leaves at similar rates during March to April, the driest period of the year. Species of both groups had approximately fully developed foliage during the warm, wet period (mid-June to mid-September) of the monsoon. However, significant differences were found at group level in other characters: shoot length (19.5 cm per shoot for deciduous and 11.7 cm for evergreen species); leaf population per 10 cm shoot length (4.7 vs 15.0); leaf area (107.9 vs 41.4 cm2/ leaf); specific leaf mass (106.9 vs 191.3 g/m2); and leaf mass loss after the monsoon period, being rapid and higher (31.6%) in deciduous species and slow and limited in the evergreens (26.2%). However, species of the two groups showed considerable overlaps in the values of above characters. The evergreen species of the Central Himalaya resembled the deciduous species of the region more than the multi-year leaves of clearly evergreen species. The evergreens bear leaves throughout the year, but like deciduous species bear the cost of annual replacement of old leaves by new leaves. They seem to outcompete deciduous species by producing annually a greater mass of leaves of low-carbon cost (per unit leaf mass), which is capable of conducting photosynthesis all year round. A situation of less marked contrast between favourable and nonfavourable periods, with respect to temperature, seems to favour the leaf characters of the evergreens.

  5. BOREAS TE-5 Leaf Gas Exchange Data

    NASA Technical Reports Server (NTRS)

    Hall, Forrest G. (Editor); Curd, Shelaine (Editor); Ehleriinger, Jim; Brooks, J. Renee; Flanagan, Larry

    2000-01-01

    The BOREAS TE-5 team collected measurements in the NSA and SSA on gas exchange, gas composition, and tree growth. The leaf photosynthetic gas exchange data were collected in the BOREAS NSA and the SSA from 06-Jun- 1994 to 13-Sep- 1994 using a LI-COR 6200 portable photosynthesis system. The data were collected to compare the photosynthetic capacity, stomata] conductance, and leaf intercellular CO, concentrations among the major tree species at the BOREAS sites. The data are average values from diurnal measurements on the upper canopy foliage (sun leaves). The data are available 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 Activity Archive Center (DAAC).

  6. [Not Available].

    PubMed

    Zecchini, Céline; Chanoine, Sébastien; Chapuis, Claire; Claustre, Johanna; Schir, Edith; Allenet, Benoît; Raymond, Christel Saint; Bedouch, Pierrick

    2015-01-01

    Advances in lung transplantation allow the women of childbearing age to consider becoming mothers. When planning to become pregnant, a therapeutic drug management of immunosuppressive drugs and associated therapies is required. It must take into account teratogenic and fetotoxic drugs, as well as pharmacokinetic changes encountered during pregnancy. Increasingly data are currently available on the management of immunosuppressive drugs and associated therapies during pregnancy. We report the case management of drug therapy before and during pregnancy in two patients after a lung or heart-lung transplantation. To prevent the emergence of complications for mother and child, a literature review has been necessary to manage drug therapies of each patient. PMID:27393315

  7. The artificial leaf.

    PubMed

    Nocera, Daniel G

    2012-05-15

    To convert the energy of sunlight into chemical energy, the leaf splits water via the photosynthetic process to produce molecular oxygen and hydrogen, which is in a form of separated protons and electrons. The primary steps of natural photosynthesis involve the absorption of sunlight and its conversion into spatially separated electron-hole pairs. The holes of this wireless current are captured by the oxygen evolving complex (OEC) of photosystem II (PSII) to oxidize water to oxygen. The electrons and protons produced as a byproduct of the OEC reaction are captured by ferrodoxin of photosystem I. With the aid of ferrodoxin-NADP(+) reductase, they are used to produce hydrogen in the form of NADPH. For a synthetic material to realize the solar energy conversion function of the leaf, the light-absorbing material must capture a solar photon to generate a wireless current that is harnessed by catalysts, which drive the four electron/hole fuel-forming water-splitting reaction under benign conditions and under 1 sun (100 mW/cm(2)) illumination. This Account describes the construction of an artificial leaf comprising earth-abundant elements by interfacing a triple junction, amorphous silicon photovoltaic with hydrogen- and oxygen-evolving catalysts made from a ternary alloy (NiMoZn) and a cobalt-phosphate cluster (Co-OEC), respectively. The latter captures the structural and functional attributes of the PSII-OEC. Similar to the PSII-OEC, the Co-OEC self-assembles upon oxidation of an earth-abundant metal ion from 2+ to 3+, may operate in natural water at room temperature, and is self-healing. The Co-OEC also activates H(2)O by a proton-coupled electron transfer mechanism in which the Co-OEC is increased by four hole equivalents akin to the S-state pumping of the Kok cycle of PSII. X-ray absorption spectroscopy studies have established that the Co-OEC is a structural relative of Mn(3)CaO(4)-Mn cubane of the PSII-OEC, where Co replaces Mn and the cubane is extended in a

  8. [Not Available].

    PubMed

    Spivak, M

    1987-01-01

    of human physiology for instance. Huge amounts of energy and money were spent on realizing this theory: politicians, educators, the military, religious authorities, men of distinction, all fought for the best possible application of this miraculous principle which was believed to cure all ills in this world. Was it really worthwhile? Was it possible to expect objectively measurable results on a national scale if the social factors - such as standards of living, hygiene, working hours, urban conditions - were not taken into account? The history of this element requires a deep understanding of the evolution of most of the factors which make up real life in a country such as France, which experienced various stages in a industrial revolution as well as many political changes. In spite of this evolution, one must acknowledge that false beliefs survived well into the 1940s, and furthermore, physical exercise, whatever its form, still belongs in many ways to hedonism and is therefore difficult to impose as a universal solution to political problems. As a democracy, France could not accept militarization. PMID:11617215

  9. [Not Available].

    PubMed

    Sibalic, V

    1996-01-01

    further education towards specializing in psychiatry. A walk through today's clinic does not only mean seeing, but also experiencing history. Situated between the walls of the former monastery of St. Pirmin, the old part of the building, with its splendid ornamentation, can transport the visitor back to former times. Life in the clinic must have been difficult: massive, cold walls, mostly badly-lit rooms and corridors temporarily filled with beds must surely have had a very unfavourable effect on the disposition of the patients. Pavilions, erected later in a more useful but nonetheless pleasing style of architecture are equally impressive - new and old harmoniously united. Even in earlier times, people praised the beautiful countryside in which Pfäfers is situated. The outward appearance of the village has not changed in years. Its high location offers a wonderful view over the valley and provides a fresh, cool climate - an advantage which will always be held in great esteem by the clinic St. Pirminsberg. PMID:11630263

  10. 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...

  11. 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...

  12. [Not Available].

    PubMed

    Kautzky-Willer, Alexandra

    2016-03-01

    Obesity is increasing worldwide in both sexes and a challenge for health professionals and the health care system. Women have more subcutaneous fat and are more insulin sensitive while men have more visceral and liver fat and higher cardiovascular risk. Women more often show the metabolically healthy obese phenotype than males. However, with increasing BMI the risk for type 2 diabetes and cardiovascular diseases increases more dramatically in women compared to males. Obese women suffer more from weight-related problems, have a higher rate of depression and seek more often medical help to reduce weight. Both biological factors and psychosocial factors contribute to the disease and interact with each other. In this special edition of the journal sex and gender aspects in prevention, treatment and development of complications will be discussed, as proposed by the Austrian Obesity Association. Data available from the Austrian population will be included in the Austrian Gender Obesity Report. PMID:26847444

  13. [Not Available].

    PubMed

    Blanchard, Elodie; de Lara, Manuel Tunon

    2013-01-01

    Pholcodine is an opioid that has been widely used worldwide since 1950 for the treatment of non-productive cough in children and adults. The results of early preclinical studies but also those of recent clinical trials have shown the antitussive efficacy of pholcodine to be superior to that of codeine, of longer duration, and with an equivalent or safer toxicity profile. Also, there is no risk of addiction. Concern had been raised over a possible cross-sensitisation with neuromuscular blocking agents. While a recent assessment of the available data by the European Medicines Agency (EMA) has confirmed the favourable risk-benefit ratio of pholcodine, further studies are needed to clear this point. PMID:27392673

  14. [Not Available].

    PubMed

    Olsen, Björn; Lundkvist, Åke

    2016-01-01

    Zika virus is a mosquito-borne flavivirus transmitted by Aedes mosquitos. The virus was discovered in 1947 in the Zika forest in Uganda. Symptomatic disease is usually mild and is characterized by maculopapular rash, headache, fever, arthralgia and conjunctivitis. Fatalities are rare. There is neither vaccine nor curative treatment available. In May 2015, the first observation of local virus transmission was reported from Brazil. During the expanding outbreak in the Americas, Zika virus infection has been associated with microcephaly in newborn and fetal losses in women infected with Zika virus during pregnancy. The main reason for the current epidemic in the Americas is the introduction of an Old World virus into a new ecosystem, with no background herd immunity in the population. It is likely that the spread of Zika virus will continue, affecting all countries in the Americas except for Chile and Canada. PMID:26978815

  15. [Not Available].

    PubMed

    Forstner, Christina; Pletz, Mathias W

    2016-02-01

    Infections with multi-drug resistant bacteria are increasing worldwide. Glycopeptides, linezolid, daptomycin and 5th generation cephalosporins ("MRSA-cephalsoporins") are used against severe infections with MRSA, combination partners are rifampin and fosfomycin. Treatment options against VRE-infections are limited to linezolid, daptomycin and tigecyclin. New agents with activity against MRSA and VRE are tedizolid, dalbvancin and oritavancin. For monotherapy of severe infections due to 3MRGN carbapenems are available. Ceftolozane/tazobactam has been licensed by the European Medical Agency and shows good activity against a relevant proportion of ESBL-pathogens. Oral agents such as nitrofurantoin or fosfomycin are used for treatment of uncomplicated cystitis. Colistin shows best in vitro susceptibility against carbapenem-resistant Enterobacteriaceae, followed by fosfomycin and tigecycline. For serious infections with 4MRGN a colistin-based combination treatment with two to three agents is recommended. In such cases a carbapenem as combination partner may be useful. PMID:26949908

  16. Variations of leaf N, P concentrations in shrubland biomes across northern China: phylogeny, climate and soil

    NASA Astrophysics Data System (ADS)

    Yang, X.; Chi, X.; Ji, C.; Liu, H.; Ma, W.; Mohhammat, A.; Shi, Z.; Wang, X.; Yu, S.; Yue, M.; Tang, Z.

    2015-11-01

    Concentrations of leaf nitrogen (N) and phosphorus (P) are key leaf traits in ecosystem functioning and dynamics. Foliar stoichiometry varies remarkably among life forms. However, previous studies have focused on trees and grasses, leaving the knowledge gap for the stoichiometric patterns of shrubs. In this study, we explored the intra- and interspecific variations of leaf N and P concentration in relation to climate, soil property and evolutionary history based on 1486 samples composed of 163 shrub species from 361 shrubland sites in northern China expanding 46.1° (86.7-132.8° E) in longitude and 19.8° (32.6-52.4° N) in latitude. The results showed that leaf N concentration decreased with precipitation, leaf P concentration decreased with temperature and increased with precipitation and soil P concentration. Both leaf N and P concentrations were phylogenetically conserved, but leaf P concentration was less conserved than leaf N concentration. At community level, climates explained more interspecific, while soil nutrient explained more intraspecific, variation of leaf nutrient concentrations. These results suggested that leaf N and P concentrations responded to climate, soil, and phylogeny in different ways. Climate influenced the community chemical traits through the shift in species composition, whereas soil directly influenced the community chemical traits.

  17. Antibacterial, Antibiofilm Effect of Burdock (Arctium lappa L.) Leaf Fraction and Its Efficiency in Meat Preservation.

    PubMed

    Lou, Zaixiang; Li, Cheng; Kou, Xingran; Yu, Fuhao; Wang, Hongxin; Smith, Gary M; Zhu, Song

    2016-08-01

    First, the antibacterial, antibiofilm effect and chemical composition of burdock (Arctium lappa L.) leaf fractions were studied. Then, the efficiency of burdock leaf fractions in pork preservation was evaluated. The results showed that burdock leaf fraction significantly inhibited the growth and biofilm development of Escherichia coli and Salmonella Typhimurium. MICs of burdock leaf fractions on E. coli and Salmonella Typhimurium were both 2 mg/ml. At a concentration of 2.0 mg/ml, the inhibition rates of the fraction on growth and development of E. coli and Salmonella Typhimurium biofilms were 78.7 and 69.9%, respectively. During storage, the log CFU per gram of meat samples treated with burdock leaf fractions decreased 2.15, compared with the samples without treatment. The shelf life of pork treated with burdock leaf fractions was extended 6 days compared with the pork without treatment, and the sensory property was obviously improved. Compared with the control group, burdock leaf fraction treatment significantly decreased the total volatile basic nitrogen value and pH of the meat samples. Chemical composition analysis showed that the burdock leaf fraction consisted of chlorogenic acid, caffeic acid, p-coumaric acid, rutin, cynarin, crocin, luteolin, arctiin, and quercetin. As a vegetable with an abundant source, burdock leaf is safe, affordable, and efficient in meat preservation, indicating that burdock leaf fraction is a promising natural preservative for pork. PMID:27497128

  18. 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

  19. [Not Available].

    PubMed

    Marugán de Miguelsanz, José Manuel; Torres Hinojal, María Del Carmen; Geijo Uribe, María Soraya; Redondo Del Río, María Paz; Mongil López, Beatriz; De Brito García-Sousa, Inés; Caballero Sanz, Irene; Eiros Bouza, José María

    2016-01-01

    Anorexia nervosa (AN) is the most prevalent of eating disorders in children and adolescents, and its treatment is long and complex, involving a multidisciplinary team. Nutritional rehabilitation and restoration of a healthy body weight is one of the central goals in the initial stages of inpatient treatment. However, current recommendations on initial energy requirements for these patients are inconsistent, with a clear lack of controlled studies, available scientific evidence and global consensus on the most effective and safe refeeding practices in hospitalized adolescents with anorexia nervosa (AN). Conservative refeeding recommendations have been classically established in order to prevent the refeeding syndrome. Nevertheless, various works have recently appeared advocating a higher initial caloric intake, without observing more complications or refeeding syndrome, and allowing a shorter average stay. We present our experience in the treatment of restricting AN with a conservative progressive treatment. We have obtained good results with this approach, which was well tolerated by patients, with no observing complications. As a consequence, the medical team could establish a pact about the therapeutic goals with the patients in an easier way. PMID:27444457

  20. [Not Available].

    PubMed

    Marugán de Miguelsanz, José Manuel; Torres Hinojal, María Del Carmen; Geijo Uribe, María Soraya; Redondo Del Río, María Paz; Mongil López, Beatriz; De Brito García-Sousa, Inés; Caballero Sanz, Irene; Eiros Bouza, José María

    2016-01-01

    Anorexia nervosa (AN) is the most prevalent of eating disorders in children and adolescents, and its treatment is long and complex, involving a multidisciplinary team. Nutritional rehabilitation and restoration of a healthy body weight is one of the central goals in the initial stages of inpatient treatment. However, current recommendations on initial energy requirements for these patients are inconsistent, with a clear lack of controlled studies, available scientific evidence and global consensus on the most effective and safe refeeding practices in hospitalized adolescents with anorexia nervosa (AN). Conservative refeeding recommendations have been classically established in order to prevent the refeeding syndrome. Nevertheless, various works have recently appeared advocating a higher initial caloric intake, without observing more complications or refeeding syndrome, and allowing a shorter average stay. We present our experience in the treatment of restricting AN with a conservative progressive treatment. We have obtained good results with this approach, which was well tolerated by patients, with no observing complications. As a consequence, the medical team could establish a pact about the therapeutic goals with the patients in an easier way. PMID:27513485

  1. [Not Available].

    PubMed

    Chaibdraa, A; Medjelekh, M S; Saouli, A; Bentakouk, M C

    2015-09-30

    Use of local/regional anesthesia in burn patients is limited by many factors. It is considered as marginal in the multimodal treatment of nociceptive pain. We conducted a retrospective study on regional anesthesia used for analgesia over a period of three years. Given the lack of available literature on this subject, the results obtained from this study will enable suggestions to be made for possible uses of this technique. We identified 634 uses of regional anesthesia of which 96% were in adults. Most cases involved the lower limbs (76%). Spinal anesthesia was performed on 32 patients, including four children. Incidents were infrequent (3%) and had no morbid consequence. Regional anesthesia may be a useful option in a multimodal strategy of analgesia, allowing early passive rehabilitation and recovery after surgical skin grafts. It should be assessed in outpatients, since 95% of burns patients are not hospitalized. Use of regional anesthesia in burn patients should generate more interest to allow the establishment of protocols in multidisciplinary reflection. PMID:27279806

  2. [Not Available].

    PubMed

    Goffinet, L; Breton, A; Gavillot, C; Barbary, S; Journeau, P; Lascombes, P; Dautel, G

    2015-09-30

    The early management of pediatric hand burns includes surgical treatment, medical follow up and prevention of abnormal scarring by splits and/or pressure garment therapy. The aim of this review was to find the best available evidence in the literature on the surgical part of this management. This review started with a search in the PubMed database for the keywords, hand AND/OR child AND/OR burn. Only the articles published between January 1(st), 2005 and January 1(st), 2011 were selected. The data were compared to French and American textbooks. Contradictory findings were reported on the timing of the excision and graft, with only two comparative studies reported, with a lot of biases. The state of the art on the initial management of hand burns in children is not totally conclusive due to the lack of statistic power in these studies, but many expert opinions help to define options for good therapeutic paradigms. It is important to include these patients in prospective protocols with both early and long-term follow-up in order to increase the amount of evidence at our disposal. PMID:27279807

  3. C:N:P Stoichiometry and Leaf Traits of Halophytes in an Arid Saline Environment, Northwest China

    PubMed Central

    Wang, Lilong; Zhao, Guanxiang; Li, Meng; Zhang, Mingting; Zhang, Lifang; Zhang, Xinfang; An, Lizhe; Xu, Shijian

    2015-01-01

    Salinization is an important and increasingly prevalent issue which has broad and profound effects on plant survival and distribution pattern. To understand the patterns and potential drivers of leaf traits in saline environments, we determined the soil properties, leaf morphological traits (specific leaf area, SLA, and leaf dry matter content, LDMC), leaf chemical traits (leaf carbon, C, nitrogen, N, and phosphorus, P, stoichiometry) based on 142 observations collected from 23 sites in an arid saline environment, which is a vulnerable ecosystem in northwest China. We also explored the relationships among leaf traits, the responses of leaf traits, and plant functional groups (herb, woody, and succulent woody) to various saline environments. The arid desert halophytes were characterized by lower leaf C and SLA levels, higher N, but stable P and N:P. The leaf morphological traits were correlated significantly with the C, N, and P contents across all observations, but they differed within each functional group. Succulent woody plants had the lowest leaf C and highest leaf N levels among the three functional groups. The growth of halophytes might be more limited by N rather than P in the study area. GLM analysis demonstrated that the soil available nutrients and plant functional groups, but not salinity, were potential drivers of leaf C:N:P stoichiometry in halophytes, whereas species differences accounted for the largest contributions to leaf morphological variations. Our study provides baseline information to facilitate the management and restoration of arid saline desert ecosystem. PMID:25798853

  4. [Not Available].

    PubMed

    Demaeyer, Ph

    2016-01-01

    Medicine owes many to Hippocrate, but pneumology traces its origin back to antiquity, from Mesopotamia to ancient Rome. Regarding prehistory: if viscera of this period have not been kept, some bones were. Since Neanderthals, it is then possible to study osteoarticular pathologies (often chronic arthrosis). But no evidence of tuberculosis was found (all thoracic kyphosis are not tuberculosis). Tuberculosis probably appears during the Neolithic age, because of high concentration of population. In ancient times, pneumology was of course not a real medical specialty. However, respiratory illness already constituted a big part of antique medical practice. The purpose of the physician in antiquity was to establish a diagnosis, a prognostic and to propose a treatment. Prognostic revealed to be of great importance in ancient times, since therapeutic efficacy was limited. Contemporary physicians often neglect this part of their practice. In ancient times, physicians also tried to gradually eliminate magic-religious aspects in taking care of the patients. This review will propose a journey from Mesopotamia to ancient Egypt (and its medical papyrus). Very few sources are available concerning medicine in pre-Columbian cultures. However, it is well known that shamans had, besides their religious competences, a great pharmacopoeia. Because of these very few sources, this topic will not be added to this article. Little is known in Europa about chinese medicine before the Jesuit mission in China during the 17th and 18th centuries. Yet, chinese medicine grew in parallel with European's one. Some relevant elements of this medicine will hereafter be shown. PMID:27120938

  5. [Not Available].

    PubMed

    Soret, Juliette; Kiladjian, Jean-Jacques

    2016-06-01

    THE ROLE OF RUXOLITINIB IN THE TREATMENT OF MYELOPROLIFERATIVE NEOPLASMS: The discovery of the JAK2V617F mutation in 2005, present in 95% of polycythemia vera (PV) and in 55% of myelofibrosis (MF) patients, opened the way for a new era of targeted therapies for myeloproliferative neoplasms. Ruxolitinib was the first-in-class Janus Kinase (JAK) inhibitor approved for the management of these diseases. In PV patients, conventional treatment strategies including aspirin, phlebotomy, cytoreductive agents such as hydroxyurea and interferon, clearly provide clinical benefits. However, some patients develop resistance or intolerance to these treatments. Ruxolitinib has been approved for PV patients who are resistant to or intolerant of hydroxyurea, based on the results of the phase 3 RESPONSE study. This study showed that ruxolitinib improves hematocrit control, reduces splenomegaly, and ameliorate disease-related symptoms as compared with best available therapy. In MF patients, the only curative treatment is allogeneic stem cell transplantation, but it remains restricted to a limited group of patients with poor prognosis and who are eligible for such procedure associated with non-negligible transplant-related mortality. Other treatments are palliative and unlikely to prolong survival. Ruxolitinib has been approved in the United States for MF patients with intermediate or high-risk disease, and in Europe for disease-related splenomegaly or symptoms in adults with MF, based on phase 3 COMFORT-I and COMFORT-II studies. These studies showed that ruxolitinib was able to reduce splenomegaly, ameliorate symptoms, and improve survival. However, the journey is not finished yet since there are still important unmet needs for MF patients, including improvement in cytopenias, and significant modification of disease natural history. PMID:27494970

  6. Scaling up stomatal conductance from leaf to canopy using a dual-leaf model for estimating crop evapotranspiration.

    PubMed

    Ding, Risheng; Kang, Shaozhong; Du, Taisheng; Hao, Xinmei; Zhang, Yanqun

    2014-01-01

    The dual-source Shuttleworth-Wallace model has been widely used to estimate and partition crop evapotranspiration (λET). Canopy stomatal conductance (Gsc), an essential parameter of the model, is often calculated by scaling up leaf stomatal conductance, considering the canopy as one single leaf in a so-called "big-leaf" model. However, Gsc can be overestimated or underestimated depending on leaf area index level in the big-leaf model, due to a non-linear stomatal response to light. A dual-leaf model, scaling up Gsc from leaf to canopy, was developed in this study. The non-linear stomata-light relationship was incorporated by dividing the canopy into sunlit and shaded fractions and calculating each fraction separately according to absorbed irradiances. The model includes: (1) the absorbed irradiance, determined by separately integrating the sunlit and shaded leaves with consideration of both beam and diffuse radiation; (2) leaf area for the sunlit and shaded fractions; and (3) a leaf conductance model that accounts for the response of stomata to PAR, vapor pressure deficit and available soil water. In contrast to the significant errors of Gsc in the big-leaf model, the predicted Gsc using the dual-leaf model had a high degree of data-model agreement; the slope of the linear regression between daytime predictions and measurements was 1.01 (R2 = 0.98), with RMSE of 0.6120 mm s-1 for four clear-sky days in different growth stages. The estimates of half-hourly λET using the dual-source dual-leaf model (DSDL) agreed well with measurements and the error was within 5% during two growing seasons of maize with differing hydrometeorological and management strategies. Moreover, the estimates of soil evaporation using the DSDL model closely matched actual measurements. Our results indicate that the DSDL model can produce more accurate estimation of Gsc and λET, compared to the big-leaf model, and thus is an effective alternative approach for estimating and partitioning

  7. Remote sensing of leaf N to improve carbon assimilation prediction

    NASA Astrophysics Data System (ADS)

    Loozen, Yasmina; Rebel, Karin; Karssenberg, Derek; de Jong, Steven; Wassen, Martin

    2016-04-01

    Predicting and understanding carbon assimilation by terrestrial vegetation remains fundamental in the context of climate change. Carbon and nitrogen cycles are linked as nitrogen is an essential nutrient for plant growth. In this respect the N cycle is integrated into vegetation models predicting vegetation carbon uptake. However plant traits within the N cycle, such as leaf nitrogen, are lacking at large scales, which complicates the calibration and optimization of the N cycling modelling modules. Remote sensing techniques could offer the possibility to detect leaf N concentration at continental scales. In fact, it has already been used to sense leaf N at local, e.g. in agricultural oriented applications, as well as at regional scales. The objective of this study is to enhance the availability of leaf N estimates in forested ecosystems at European scale using remote sensing products. European forest leaf N data were obtained from the TRY database. The MERIS Terrestrial chlorophyll Index (MTCI) Level 3 product as well as two reflectance bands in the NIR region (band centers at 865 and 885nm) both from MERIS aboard ENVISAT (ESA) were used to study statistical relationship with leaf N data. In a first step, we analyzed 1892 Catalonian (NE Spain) forest plots using a linear regression method. The regressions results between leaf N and either MTCI or NIR bands were significant (p< 0.001). The R-square for the regression between leaf N and MTCI was equal to 0.13. The method performed better for broadleaves deciduous plots (R-square = 0.11) than for needleleaves or broadleaves evergreen plots. The relationship between leaf N and MTCI was also higher for the plots sampled during summer (R-square = 0.28 in July) than for the plots sampled during the rest of the year. In a second step the method will be applied on and will include more diverse forest types at the European level.

  8. Role of ethylene in responses of plants to nitrogen availability

    PubMed Central

    Khan, M. I. R.; Trivellini, Alice; Fatma, Mehar; Masood, Asim; Francini, Alessandra; Iqbal, Noushina; Ferrante, Antonio; Khan, Nafees A.

    2015-01-01

    Ethylene is a plant hormone involved in several physiological processes and regulates the plant development during the whole life. Stressful conditions usually activate ethylene biosynthesis and signaling in plants. The availability of nutrients, shortage or excess, influences plant metabolism and ethylene plays an important role in plant adaptation under suboptimal conditions. Among the plant nutrients, the nitrogen (N) is one the most important mineral element required for plant growth and development. The availability of N significantly influences plant metabolism, including ethylene biology. The interaction between ethylene and N affects several physiological processes such as leaf gas exchanges, roots architecture, leaf, fruits, and flowers development. Low plant N use efficiency (NUE) leads to N loss and N deprivation, which affect ethylene biosynthesis and tissues sensitivity, inducing cell damage and ultimately lysis. Plants may respond differently to N availability balancing ethylene production through its signaling network. This review discusses the recent advances in the interaction between N availability and ethylene at whole plant and different organ levels, and explores how N availability induces ethylene biology and plant responses. Exogenously applied ethylene seems to cope the stress conditions and improves plant physiological performance. This can be explained considering the expression of ethylene biosynthesis and signaling genes under different N availability. A greater understanding of the regulation of N by means of ethylene modulation may help to increase NUE and directly influence crop productivity under conditions of limited N availability, leading to positive effects on the environment. Moreover, efforts should be focused on the effect of N deficiency or excess in fruit trees, where ethylene can have detrimental effects especially during postharvest. PMID:26579172

  9. Solubility of leaf litter phosphorus and nitrogen from taiga and lowland tropical forest

    NASA Astrophysics Data System (ADS)

    Schreeg, L.; Mack, M. C.; Turner, B. L.

    2011-12-01

    Leaf litter returns significant quantities of phosphorus (P) and nitrogen (N) to the soil environment in terrestrial ecosystems. The release of litter nutrients during decomposition can occur through mineralization of organic material and leaching. While leaching is an important component in our conceptual models of decomposition, the role of leaching in P and N release from leaf litter has been little investigated. Here we synthesize the results from two studies using recently senesced litter from taiga in Siberia and lowland tropical forest in Panama. We show that leaf litter P is highly soluble. On average, 35±10% (mean ± standard deviation) of total litter P was soluble from 41 species of trees and lianas from a lowland tropical forest during a 4 h extract. Similarly, the soluble fraction of litter P was high for recently senesced litter from the taiga - an average of 40±15% of total P was water soluble during a 24 h extract across nine species, which included a sedge, a tree and shrubs spanning two topographical positions (i.e., floodplain and upland). For both systems P extracted per gram litter mass was strongly predicted by total P concentration in initial litter (r2=0.66, p<0.001 in tropical forest; r2=0.63, p<0.001 in taiga). In addition, greater than 80% of the soluble P was inorganic P, suggesting leached P is readily available to plants and microbes. In contrast, litter N was relatively less soluble (<10±5% of the total leaf N on average for both systems), water soluble N per unit litter mass was only weakly predicted by total litter N (r2<0.35 for both systems), and organic N was prominent in extracts. The similarity in solubility results from two distinct latitudes and multiple life forms suggests differences in litter P and N solubility may be fundamental to how these two key nutrients cycle in terrestrial ecosystems across the globe.

  10. 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

  11. BOREAS TE-5 Leaf Carbon Isotope Data

    NASA Technical Reports Server (NTRS)

    Hall, Forrest G. (Editor); Curd, Shelaine (Editor); Ehleriinger, Jim; Brooks, J. Renee; Flanagan, Larry

    2000-01-01

    The BOREAS TE-5 team collected measurements in the NSA and SSA on gas exchange, gas composition, and tree growth. This documentation describes leaf carbon isotope data that were collected in 1993 and 1994 at the NSA and SSA OJP sites, the SSA OBS site, and the NSA UBS site. In addition, leaf carbon isotope data were collected in 1994 only at the NSA and SSA OA sites. These data was collected to provide seasonal integrated physiological information for 10 to 15 common species at these 6 BOREAS sites. The data are stored 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).

  12. 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.

  13. 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

  14. 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...

  15. 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...

  16. 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...

  17. 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...

  18. 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...

  19. Scaling Up Stomatal Conductance from Leaf to Canopy Using a Dual-Leaf Model for Estimating Crop Evapotranspiration

    PubMed Central

    Ding, Risheng; Kang, Shaozhong; Du, Taisheng; Hao, Xinmei; Zhang, Yanqun

    2014-01-01

    The dual-source Shuttleworth-Wallace model has been widely used to estimate and partition crop evapotranspiration (λET). Canopy stomatal conductance (Gsc), an essential parameter of the model, is often calculated by scaling up leaf stomatal conductance, considering the canopy as one single leaf in a so-called “big-leaf” model. However, Gsc can be overestimated or underestimated depending on leaf area index level in the big-leaf model, due to a non-linear stomatal response to light. A dual-leaf model, scaling up Gsc from leaf to canopy, was developed in this study. The non-linear stomata-light relationship was incorporated by dividing the canopy into sunlit and shaded fractions and calculating each fraction separately according to absorbed irradiances. The model includes: (1) the absorbed irradiance, determined by separately integrating the sunlit and shaded leaves with consideration of both beam and diffuse radiation; (2) leaf area for the sunlit and shaded fractions; and (3) a leaf conductance model that accounts for the response of stomata to PAR, vapor pressure deficit and available soil water. In contrast to the significant errors of Gsc in the big-leaf model, the predicted Gsc using the dual-leaf model had a high degree of data-model agreement; the slope of the linear regression between daytime predictions and measurements was 1.01 (R2 = 0.98), with RMSE of 0.6120 mm s−1 for four clear-sky days in different growth stages. The estimates of half-hourly λET using the dual-source dual-leaf model (DSDL) agreed well with measurements and the error was within 5% during two growing seasons of maize with differing hydrometeorological and management strategies. Moreover, the estimates of soil evaporation using the DSDL model closely matched actual measurements. Our results indicate that the DSDL model can produce more accurate estimation of Gsc and λET, compared to the big-leaf model, and thus is an effective alternative approach for estimating and

  20. 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.

  1. 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

  2. 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

  3. Costs of measuring leaf area index of corn

    NASA Technical Reports Server (NTRS)

    Daughtry, C. S. T.; Hollinger, S. E.

    1984-01-01

    The magnitude of plant-to-plant variability of leaf area of corn plants selected from uniform plots was examined and four representative methods for measuring leaf area index (LAI) were evaluated. The number of plants required and the relative costs for each sampling method were calculated to detect 10, 20, and 50% differences in LAI using 0.05 and 0.01 tests of significance and a 90% probability of success (beta = 0.1). The natural variability of leaf area per corn plant was nearly 10%. Additional variability or experimental error may be introduced by the measurement technique employed and by nonuniformity within the plot. Direct measurement of leaf area with an electronic area meter had the lowest CV, required that the fewest plants be sampled, but required approximately the same amount of time as the leaf area/weight ratio method to detect comparable differences. Indirect methods based on measurements of length and width of leaves required more plants but less total time than the direct method. Unless the coefficients for converting length and width to area are verified frequently, the indirect methods may be biased. When true differences in LAI among treatments exceed 50% of mean, all four methods are equal. The method of choice depends on the resources available, the differences to be detected, and what additional information, such as leaf weight or stalk weight, is also desired.

  4. A quest for the artificial leaf.

    PubMed

    Janna Olmos, Julian David; Kargul, Joanna

    2015-09-01

    It has been estimated that the energy captured in one hour of sunlight that reaches our planet is equivalent to annual energy production by human population globally. To efficiently capture the practically inexhaustible solar energy and convert it into high energy density solar fuels provides an attractive 'green' alternative to running our present day economies on rapidly depleting fossil fuels, especially in the context of ever growing global energy demand. Natural photosynthesis represents one of the most fundamental processes that sustain life on Earth. It provides nearly all the oxygen we breathe, the food we consume and fossil fuels that we so much depend on. Imitating the reactions that occur at the early stages of photosynthesis represents the main challenge in the quest for construction of an efficient, robust, self-renewing and cost-effective 'artificial leaf'. In this review we summarize the main molecular features of the natural solar energy converters, photosystem I and photosystem II, that allow them to operate at high quantum efficiencies, and thus inspire the smart matrix design of the artificial solar-to-fuel devices. We also discuss the main challenges that face the field and overview selected recent technological advances that have tremendously accelerated the race for a fully operational artificial leaf that could serve as a viable alternative to fossil fuels for energy production. PMID:26183656

  5. Quantitative trait locus analysis of leaf dissection in tomato using Lycopersicon pennellii segmental introgression lines.

    PubMed Central

    Holtan, Hans E E; Hake, Sarah

    2003-01-01

    Leaves are one of the most conspicuous and important organs of all seed plants. A fundamental source of morphological diversity in leaves is the degree to which the leaf is dissected by lobes and leaflets. We used publicly available segmental introgression lines to describe the quantitative trait loci (QTL) controlling the difference in leaf dissection seen between two tomato species, Lycopersicon esculentum and L. pennellii. We define eight morphological characteristics that comprise the mature tomato leaf and describe loci that affect each of these characters. We found 30 QTL that contribute one or more of these characters. Of these 30 QTL, 22 primarily affect leaf dissection and 8 primarily affect leaf size. On the basis of which characters are affected, four classes of loci emerge that affect leaf dissection. The majority of the QTL produce phenotypes intermediate to the two parent lines, while 5 QTL result in transgression with drastically increased dissection relative to both parent lines. PMID:14668401

  6. 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.

  7. 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

  8. BOREAS TE-12 Leaf Gas Exchange Data

    NASA Technical Reports Server (NTRS)

    Hall, Forrest G. (Editor); Curd, Shelaine (Editor); Arkebauer, Timothy J.; Yang, Litao

    2000-01-01

    The BOREAS TE-12 team collected several data sets in support of its efforts to characterize and interpret information on the reflectance, transmittance, and gas exchange of boreal vegetation. This data set contains measurements of leaf gas exchange conducted in the SSA during the growing seasons of 1994 and 1995 using a portable gas exchange system. The data are stored 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 Center (DAAC).

  9. Leaf manganese accumulation and phosphorus-acquisition efficiency.

    PubMed

    Lambers, Hans; Hayes, Patrick E; Laliberté, Etienne; Oliveira, Rafael S; Turner, Benjamin L

    2015-02-01

    Plants that deploy a phosphorus (P)-mobilising strategy based on the release of carboxylates tend to have high leaf manganese concentrations ([Mn]). This occurs because the carboxylates mobilise not only soil inorganic and organic P, but also a range of micronutrients, including Mn. Concentrations of most other micronutrients increase to a small extent, but Mn accumulates to significant levels, even when plants grow in soil with low concentrations of exchangeable Mn availability. Here, we propose that leaf [Mn] can be used to select for genotypes that are more efficient at acquiring P when soil P availability is low. Likewise, leaf [Mn] can be used to screen for belowground functional traits related to nutrient-acquisition strategies among species in low-P habitats. PMID:25466977

  10. Environmental modification of yield and food composition of cowpea and leaf lettuce

    NASA Technical Reports Server (NTRS)

    Mitchell, Cary A.; Nielsen, Suzanne S.; Bubenheim, David L.

    1990-01-01

    Cowpea (Vigna unguiculata (L.) Walp.) and leaf lettuce (Lactuca sativa L.) are candidate species to provide ligume protein and starch or serve as a salad base for a nutritionally balanced and psychologically satisfying vegetarian diet in the Controlled Ecology Life Support System (CELSS). Various nutritional parameters are reported. Hydroponic leaf lettuce grew best under CO2 enrichment and photosynthetic photon flux (PPF) enhancement. Leaf protein content reached 36 percent with NH4(+) + NO3 nutrition; starch and free sugar content was as high as 7 or 8.4 percent of DW, respectively, for high PPF/CO2 enriched environments.

  11. Leaf traits and associated ecosystem characteristics across subtropical and timberline forests in the Gongga Mountains, Eastern Tibetan Plateau.

    PubMed

    Luo, Tianxiang; Luo, Ji; Pan, Yude

    2005-01-01

    Knowledge of how leaf characteristics might be used to deduce information on ecosystem functioning and how this scaling task could be done is limited. In this study, we present field data for leaf lifespan, specific leaf area (SLA) and mass and area-based leaf nitrogen concentrations (N(mass), N(area)) of dominant tree species and the associated stand foliage N-pool, leaf area index (LAI), root biomass, aboveground biomass, net primary productivity (NPP) and soil available-N content in six undisturbed forest plots along subtropical to timberline gradients on the eastern slope of the Gongga Mountains. We developed a methodology to calculate the whole-canopy mean leaf traits to include all tree species (groups) in each of the six plots through a series of weighted averages scaled up from leaf-level measurements. These defined whole-canopy mean leaf traits were equivalent to the traits of a leaf in regard to their interrelationships and altitudinal trends, but were more useful for large-scale pattern analysis of ecosystem structure and function. The whole-canopy mean leaf lifespan and leaf N(mass) mainly showed significant relationships with stand foliage N-pool, NPP, LAI and root biomass. In general, as elevation increased, the whole-canopy mean leaf lifespan and leaf N(area) and stand LAI and foliage N-pool increased to their maximum, whereas the whole-canopy mean SLA and leaf N(mass) and stand NPP and root biomass decreased from their maximum. The whole-canopy mean leaf lifespan and stand foliage N-pool both converged towards threshold-like logistic relationships with annual mean temperature and soil available-N variables. Our results are further supported by additional literature data in the Americas and eastern China. PMID:15549405

  12. Leaf longevity of Oxalis acetosella (Oxalidaceae) in the Catskill Mountains, New York, USA.

    PubMed

    Tessier, Jack T

    2004-09-01

    Leaf habit correlates with multiple physiological traits. Understanding ecophysiology is therefore dependent on knowledge of leaf habit. A variety of leaf habits exists within forest understory plant communities. Oxalis acetosella is one such understory plant and has long been considered a wintergreen, meaning that it keeps a set of leaves for one full year, replacing them with a new set during spring. To assess the leaf habit of O. acetosella and place it into a classification scheme of leaf habits, leaves of four populations of O. acetosella were repeatedly censused for two years in a northern hardwood forest of the Catskill Mountains, New York, USA. New leaves developed and old leaves senesced throughout the year, yielding a continual replacement of leaves and a summer peak in leaf number. Leaves that developed in the fall and winter had longer maximum life spans than leaves that developed during the summer. The name "seasonalgreen" is suggested to describe the continual development, senescence, and presence of leaves and annual peak in leaf number within O. acetosella. The functional significance of this leaf habit in this species and the possibility of its presence in other species deserve further study. PMID:21652370

  13. Isolation and Structure Elucidation of the Terpene "[beta]"-Thujone from Cedar Leaf Oil

    ERIC Educational Resources Information Center

    French, Larry G.

    2011-01-01

    Western red cedar leaf affords an essential oil characterized by high thujone content. Students in an advanced organic chemistry lab course isolate a single thujone diastereoisomer from commercially available cedar leaf oil. Treatment of crude oil, containing roughly 70% thujone, predominately as [alpha]-thujone (6.5:1), with ethanolic sodium…

  14. Is the spherical leaf inclination angle distribution a valid assumption for temperate and boreal tree and shrub species?

    NASA Astrophysics Data System (ADS)

    Pisek, J.

    2012-12-01

    Directional distribution of leaves is one primary parameter for determining the radiation transmission through the canopy. When inverting canopy transmittance measurements for estimating the leaf area index or foliage clumping, incorrect assumptions on leaf angles may lead to considerable errors. Often spherical distribution of leaf normals is assumed, i.e. leaf normals are assumed to have no preferred direction in situations where no measurement data are available. The goal of this study is to examine if a spherical leaf angle distribution and the resulting isotropic G-function (G≡0.5) is indeed a valid assumption for temperate and boreal tree and shrub species. Leaf angle distributions were measured for over 80 deciduous broadleaf species commonly found in temperate and boreal ecoclimatic regions. The leaf inclination angles were obtained by sampling the complete vertical extent of trees and shrubs using a recently introduced technique based on digital photography. It is found a spherical leaf angle distribution is not a valid assumption for both tree and shrub species in temperate and boreal ecoclimatic regions. Given the influence of leaf angle distribution on inverting clumping and LAI estimates from canopy transmittance measurements, it is recommended to use planophile or plagiophile leaf angle distribution as more appropriate for modeling radiation transmission in temperate and boreal ecoclimatic regions when no actual leaf inclination angle measurements are available.

  15. Variations of leaf N and P concentrations in shrubland biomes across northern China: phylogeny, climate, and soil

    NASA Astrophysics Data System (ADS)

    Yang, Xian; Chi, Xiulian; Ji, Chengjun; Liu, Hongyan; Ma, Wenhong; Mohhammat, Anwar; Shi, Zhaoyong; Wang, Xiangping; Yu, Shunli; Yue, Ming; Tang, Zhiyao

    2016-08-01

    Concentrations of leaf nitrogen (N) and phosphorus (P) are two key traits of plants for ecosystem functioning and dynamics. Foliar stoichiometry varies remarkably among life forms. However, previous studies have focused on the stoichiometric patterns of trees and grasses, leaving a significant knowledge gap for shrubs. In this study, we explored the intraspecific and interspecific variations of leaf N and P concentrations in response to the changes in climate, soil property, and evolutionary history. We analysed 1486 samples composed of 163 shrub species from 361 shrubland sites in northern China encompassing 46.1° (86.7-132.8° E) in longitude and 19.8° (32.6-52.4° N) in latitude. Leaf N concentrations decreased with precipitation, while leaf P concentrations decreased with temperature and increased with precipitation and soil total P concentrations. Both leaf N and P concentrations were phylogenetically conserved, but leaf P concentrations were less conserved than leaf N concentrations. At the community level, climate explained more interspecific variation of leaf nutrient concentrations, while soil nutrients explained most of the intraspecific variation. These results suggested that leaf N and P concentrations responded to climate, soil, and phylogeny in different ways. Climate influenced the community chemical traits through the shift in species composition, whereas soil directly influenced the community chemical traits. New patterns were discovered using our observations on specific regions and vegetation types, which improved our knowledge of broad biogeographic patterns of leaf chemical traits.

  16. Rapid Leaf Deployment Strategies in a Deciduous Savanna.

    PubMed

    February, Edmund Carl; Higgins, Steven Ian

    2016-01-01

    Deciduous plants avoid the costs of maintaining leaves in the unfavourable season, but carry the costs of constructing new leaves every year. Deciduousness is therefore expected in ecological situations with pronounced seasonality and low costs of leaf construction. In our study system, a seasonally dry tropical savanna, many trees are deciduous, suggesting that leaf construction costs must be low. Previous studies have, however, shown that nitrogen is limiting in this system, suggesting that leaf construction costs are high. Here we examine this conundrum using a time series of soil moisture availability, leaf phenology and nitrogen distribution in the tree canopy to illustrate how trees resorb nitrogen before leaf abscission and use stored reserves of nitrogen and carbon to construct new leaves at the onset of the growing season. Our results show that trees deployed leaves shortly before and in anticipation of the first rains with its associated pulse of nitrogen mineralisation. Our results also show that trees rapidly constructed a full canopy of leaves within two weeks of the first rains. We detected an increase in leaf nitrogen content that corresponded with the first rains and with the movement of nitrogen to more distal branches, suggesting that stored nitrogen reserves are used to construct leaves. Furthermore the stable carbon isotope ratios (δ13C) of these leaves suggest the use of stored carbon for leaf construction. Our findings suggest that the early deployment of leaves using stored nitrogen and carbon reserves is a strategy that is integrally linked with the onset of the first rains. This strategy may confer a competitive advantage over species that deploy leaves at or after the onset of the rains. PMID:27310398

  17. Interpreting chlorophyll fluorescence signals: the effects of leaf age

    NASA Astrophysics Data System (ADS)

    Albert, L.; Vergeli, P.; Martins, G.; Saleska, S. R.; Huxman, T. E.

    2015-12-01

    Remote sensing of sun-induced chlorophyll fluorescence (SIF) promises robust estimation of carbon uptake across landscapes, as studies of plant physiology have shown that fluorescence emission is directly linked to photosynthesis at the leaf level. Yet most leaf-level studies demonstrating the link between chlorophyll fluorescence and photosynthesis have studied leaves in their prime: leaves that recently finished expansion and have yet to senesce. By contrast, remote sensing of landscapes involves observing leaves of different ages. For example, broadleaf deciduous forests and annual plant communities in temperate regions have leaves that develop and then senesce over the course of a growing season. In this experiment, we explored how leaf age and moisture availability affect steady-state fluoresence (Fs) at the leaf level. We simultaneously measured net photosynthesis (Anet) and Fs for leaves of known ages on greenhouse-grown dwarf Helianthus Annuus (sunflowers) from two watering treatments. To monitor plant water status, we measured pre-dawn water potential, and, for a subset of leaves, osmotic potential. Fully expanded or near-fully expanded leaves (~8 to ~23 days old) had higher Anet at saturating light than young, expanding leaves (less than 8 days old) or old leaves nearing senescence (>23 days old). We found a positive relationship between Fs and Anet, suggesting that the link between fluorescence emission and photosynthesis is robust across leaves of different ages. However, leaf age had marked effects on the light response curve of photosynthesis and fluorescence metrics. These results suggest that leaf age distribution, and changes in leaf age distribution due to phenology, should be considered when interpreting SIF at the landscape level.

  18. Rapid Leaf Deployment Strategies in a Deciduous Savanna

    PubMed Central

    2016-01-01

    Deciduous plants avoid the costs of maintaining leaves in the unfavourable season, but carry the costs of constructing new leaves every year. Deciduousness is therefore expected in ecological situations with pronounced seasonality and low costs of leaf construction. In our study system, a seasonally dry tropical savanna, many trees are deciduous, suggesting that leaf construction costs must be low. Previous studies have, however, shown that nitrogen is limiting in this system, suggesting that leaf construction costs are high. Here we examine this conundrum using a time series of soil moisture availability, leaf phenology and nitrogen distribution in the tree canopy to illustrate how trees resorb nitrogen before leaf abscission and use stored reserves of nitrogen and carbon to construct new leaves at the onset of the growing season. Our results show that trees deployed leaves shortly before and in anticipation of the first rains with its associated pulse of nitrogen mineralisation. Our results also show that trees rapidly constructed a full canopy of leaves within two weeks of the first rains. We detected an increase in leaf nitrogen content that corresponded with the first rains and with the movement of nitrogen to more distal branches, suggesting that stored nitrogen reserves are used to construct leaves. Furthermore the stable carbon isotope ratios (δ13C) of these leaves suggest the use of stored carbon for leaf construction. Our findings suggest that the early deployment of leaves using stored nitrogen and carbon reserves is a strategy that is integrally linked with the onset of the first rains. This strategy may confer a competitive advantage over species that deploy leaves at or after the onset of the rains. PMID:27310398

  19. 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

  20. 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

  1. Experimental manipulation of leaf litter colonization by aquatic invertebrates in a third order tropical stream.

    PubMed

    Uieda, V S; Carvalho, E M

    2015-05-01

    Through a manipulative experiment, the colonization of leaf litter by invertebrates was investigated in two sections of a tropical stream (spatial scale) that differed in function of the canopy cover, one with the presence (closed area) and another without riparian vegetation (open area), during one month of the dry and one of the wet season (temporal scale). The work aimed to verify differences related to four variables: season, canopy cover, leaf type and leaf condition. Litter bags containing arboreal and herbaceous leaves (leaf type variable), non-conditioned and preconditioned (leaf condition variable) were placed at the bottom of the stream in each area (canopy cover variable) and season (dry and wet), and removed after 13-day colonization. The analysis of the remaining litter dry mass per leaf bag emphasizes differences related mainly to seasonality, canopy cover and leaf type, although leaf condition was also important when combined with those three factors. Comparing the abundance of invertebrates per treatment, there was a tendency of high predominance of Chironomidae during the dry season and greater taxa diversity and evenness during the wet season, when the water flow increase could alter the availability of microhabitats for local fauna. Even though canopy cover alone was not a significant source of variation in the abundance of invertebrates, the results showed a tendency of a combined effect of canopy cover with seasonality and leaf condition. PMID:26132025

  2. 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...

  3. 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

  4. 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 ...

  5. Does investment in leaf defenses drive changes in leaf economic strategy? A focus on whole-plant ontogeny.

    PubMed

    Mason, Chase M; Donovan, Lisa A

    2015-04-01

    Leaf defenses have long been studied in the context of plant growth rate, resource availability, and optimal investment theory. Likewise, one of the central modern paradigms of plant ecophysiology, the leaf economics spectrum (LES), has been extensively studied in the context of these factors across ecological scales ranging from global species data sets to temporal shifts within individuals. Despite strong physiological links between LES strategy and leaf defenses in structure, function, and resource investment, the relationship between these trait classes has not been well explored. This study investigates the relationship between leaf defenses and LES strategy across whole-plant ontogeny in three diverse Helianthus species known to exhibit dramatic ontogenetic shifts in LES strategy, focusing primarily on physical and quantitative chemical defenses. Plants were grown under controlled environmental conditions and sampled for LES and defense traits at four ontogenetic stages. Defenses were found to shift strongly with ontogeny, and to correlate strongly with LES strategy. More advanced ontogenetic stages with more conservative LES strategy leaves had higher tannin activity and toughness in all species, and higher leaf dry matter content in two of three species. Modeling results in two species support the conclusion that changes in defenses drive changes in LES strategy through ontogeny, and in one species that changes in defenses and LES strategy are likely independently driven by ontogeny. Results of this study support the hypothesis that leaf-level allocation to defenses might be an important determinant of leaf economic traits, where high investment in defenses drives a conservative LES strategy. PMID:25480481

  6. Pressure Actuated Leaf Seals for Improved Turbine Shaft Sealing

    NASA Technical Reports Server (NTRS)

    Grondahl, Clayton

    2006-01-01

    This presentation introduces a shaft seal in which leaf seal elements are constructed from slotted shim material formed and layered into a frusto-conical assembly. Limited elastic deflection of seal leaves with increasing system pressure close large startup clearance to a small, non-contacting, steady state running clearance. At shutdown seal elements resiliently retract as differential seal pressure diminishes. Large seal clearance during startup and shutdown provides a mechanism for rub avoidance. Minimum operating clearance improves performance and non-contacting operation promises long seal life. Design features of this seal, sample calculations at differential pressures up to 2400 psid and benefit comparison with brush and labyrinth seals is documented in paper, AIAA 2005 3985, presented at the Advanced Seal Technology session of the Joint Propulsion Conference in Tucson this past July. In this presentation use of bimetallic leaf material will be discussed. Frictional heating of bimetallic leaf seals during a seal rub can relieve the rub condition to some extent with a change in seal shape. Improved leaf seal rub tolerance is expected with bimetallic material.

  7. 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...

  8. 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,...

  9. 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,...

  10. 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,...

  11. 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,...

  12. 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,...

  13. 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,...

  14. 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,...

  15. 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,...

  16. 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,...

  17. 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,...

  18. 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,...

  19. 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,...

  20. 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,...

  1. 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,...

  2. 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

  3. 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...

  4. 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...

  5. 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...

  6. 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...

  7. 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...

  8. Peach leaf responses to soil and cement dust pollution.

    PubMed

    Maletsika, Persefoni A; Nanos, George D; Stavroulakis, George G

    2015-10-01

    Dust pollution can negatively affect plant productivity in hot, dry and with high irradiance areas during summer. Soil or cement dust were applied on peach trees growing in a Mediterranean area with the above climatic characteristics. Soil and cement dust accumulation onto the leaves decreased the photosynthetically active radiation (PAR) available to the leaves without causing any shade effect. Soil and mainly cement dust deposition onto the leaves decreased stomatal conductance, photosynthetic and transpiration rates, and water use efficiency due possibly to stomatal blockage and other leaf cellular effects. In early autumn, rain events removed soil dust and leaf functions partly recovered, while cement dust created a crust partially remaining onto the leaves and causing more permanent stress. Leaf characteristics were differentially affected by the two dusts studied due to their different hydraulic properties. Leaf total chlorophyll decreased and total phenol content increased with dust accumulation late in the summer compared to control leaves due to intense oxidative stress. The two dusts did not cause serious metal imbalances to the leaves, except of lower leaf K content. PMID:26054460

  9. 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. (

  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. 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...

  12. 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...

  13. 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...

  14. 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...

  15. 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...

  16. 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...

  17. 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...

  18. 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...

  19. 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...

  20. 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...

  1. 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

  2. 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

  3. 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

  4. 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

  5. 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

  6. Leaf architectural, vascular and photosynthetic acclimation to temperature in two biennials.

    PubMed

    Muller, Onno; Stewart, Jared J; Cohu, Christopher M; Polutchko, Stephanie K; Demmig-Adams, Barbara; Adams, William W

    2014-12-01

    Acclimation of leaf features to growth temperature was investigated in two biennials (whose life cycle spans summer and winter seasons) using different mechanisms of sugar loading into exporting conduits, Verbascum phoeniceum (employs sugar-synthesizing enzymes driving symplastic loading through plasmodesmatal wall pores of phloem cells) and Malva neglecta (likely apoplastic loader transporting sugar via membrane transport proteins of phloem cells). In both species, acclimation to lower temperature involved greater maximal photosynthesis rates and vein density per leaf area in close correlation with modification of minor vein cellular features. While the symplastically loading biennial exhibited adjustments in the size of minor leaf vein cells (consistent with adjustment of the level of sugar-synthesizing enzymes), the putative apoplastic biennial exhibited adjustments in the number of cells (consistent with adjustment of cell membrane area for transporter placement). This upregulation of morphological and anatomical features at lower growth temperature likely contributes to the success of both the species during the winter. Furthermore, while acclimation to low temperature involved greater leaf mass per area in both species, this resulted from greater leaf thickness in V. phoeniceum vs a greater number of mesophyll cells per leaf area in M. neglecta. Both types of adjustments presumably accommodate more chloroplasts per leaf area contributing to photosynthesis. Both biennials exhibited high foliar vein densities (particularly the solar-tracking M. neglecta), which should aid both sugar export from and delivery of water to the leaves. PMID:24818515

  7. Environmental modification of yield and nutrient composition of 'Waldmann's Green' leaf lettuce

    NASA Technical Reports Server (NTRS)

    Mitchell, C. A.; Chun, C.; Brandt, W. E.; Nielsen, S. S.

    1997-01-01

    Leaf number, dry weight, and nutrient composition of Lactuca sativa L. cv. Waldmann's Green leaves were compared following 9 days of treatment in a controlled environment room under various combinations of photosynthetic photon flux (PPF:350 vs 800 micromoles m-2 s-1), atmospheric CO2 level (ambient vs 1500 micromoles mol-1), and single-strength (1X:15 mM) vs double-strength (2X:30 mM) nitrogen (N) as NO3- alone or as NH4(+) + NO3- (1:5 molar ratio). CO2 enrichment greatly enhanced leaf number under all PPF and N conditions, but increased leaf dry weight only at high PPF. Conditions favoring high photosynthesis enhanced leaf starch content 3-fold, and protein content increased as much as 64% with 2X NH4(+)+NO3-. Free sugar content was 6 to 9% of leaf dry weight for all treatment combinations, while fat was 1.5 to 3.5%. Ash content varied from 15 to 20% of leaf dry weight. Modified controlled environments can be used to enhance the nutritional content as well as the yield of crops to be used for life support in space-deployed, self-sustaining human habitats. Leaf lettuce is a useful model crop for demonstrating the potential of nutritional value added by environmental manipulation.

  8. Cold tolerance of the montane Sierra leaf beetle, Chrysomela aeneicollis.

    PubMed

    Boychuk, Evelyn C; Smiley, John T; Dahlhoff, Elizabeth P; Bernards, Mark A; Rank, Nathan E; Sinclair, Brent J

    2015-10-01

    Small ectothermic animals living at high altitude in temperate latitudes are vulnerable to lethal cold throughout the year. Here we investigated the cold tolerance of the leaf beetle Chrysomela aeneicollis living at high elevation in California's Sierra Nevada mountains. These insects spend over half their life cycle overwintering, and may therefore be vulnerable to winter cold, and prior studies have demonstrated that survival is reduced by exposure to summertime cold. We identify overwintering microhabitat of this insect, describe cold tolerance strategies in all life stages, and use microclimate data to determine the importance of snow cover and microhabitat buffering for overwinter survival. Cold tolerance varies among life history stages and is typically correlated with microhabitat temperature: cold hardiness is lowest in chill-susceptible larvae, and highest in freeze-tolerant adults. Hemolymph osmolality is higher in quiescent (overwintering) than summer adults, primarily, but not exclusively, due to elevated hemolymph glycerol. In nature, adult beetles overwinter primarily in leaf litter and suffer high mortality if early, unseasonable cold prevents them from entering this refuge. These data suggest that cold tolerance is tightly linked to life stage. Thus, population persistence of montane insects may become problematic as climate becomes more unpredictable and climate change uncouples the phenology of cold tolerance and development from the timing of extreme cold events. PMID:26231921

  9. A leaf-rolling weevil benefits from general saprophytic fungi in polysaccharide degradation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Insects form symbiosis with fungi widely, especially those feeding on leaf litter. As dead plant tissues provide poor quality diets which contain relatively high levels of indigestible lignin and cellulose, saprophytic fungi may increase nutrient availability by polysaccharide degradation. Although ...

  10. Seedling growth and biomass allocation in relation to leaf habit and shade tolerance among 10 temperate tree species.

    PubMed

    Modrzyński, Jerzy; Chmura, Daniel J; Tjoelker, Mark G

    2015-08-01

    Initial growth of germinated seeds is an important life history stage, critical for establishment and succession in forests. Important questions remain regarding the differences among species in early growth potential arising from shade tolerance. In addition, the role of leaf habit in shaping relationships underlying shade tolerance-related differences in seedling growth remains unresolved. In this study we examined variation in morphological and physiological traits among seedlings of 10 forest tree species of the European temperate zone varying in shade tolerance and leaf habit (broadleaved winter-deciduous species vs needle-leaved conifers) during a 10-week period. Seeds were germinated and grown in a controlled environment simulating an intermediate forest understory light environment to resolve species differences in initial growth and biomass allocation. In the high-resource experimental conditions during the study, seedlings increased biomass allocation to roots at the cost of leaf biomass independent of shade tolerance and leaf habit. Strong correlations between relative growth rate (RGR), net assimilation rate (NAR), leaf area ratio (LAR), specific leaf area (SLA) and leaf mass fraction (LMF) indicate that physiology and biomass allocation were equally important determinants of RGR as plant structure and leaf morphology among these species. Our findings highlight the importance of seed mass- and seed size-related root morphology (specific root length-SRL) for shade tolerance during early ontogeny. Leaf and plant morphology (SLA, LAR) were more successful in explaining variation among species due to leaf habit than shade tolerance. In both broadleaves and conifers, shade-tolerant species had lower SRL and greater allocation of biomass to stems (stem mass fraction). Light-seeded shade-intolerant species with greater SRL had greater RGR in both leaf habit groups. However, the greatest plant mass was accumulated in the group of heavy-seeded shade

  11. The Leaf Size–Twig Size Spectrum of Temperate Woody Species Along an Altitudinal Gradient: An Invariant Allometric Scaling Relationship

    PubMed Central

    SUN, SHUCUN; JIN, DONGMEI; SHI, PEILI

    2006-01-01

    • Background and Aims The leaf size–twig size spectrum is one of the leading dimensions of plant ecological variation, and now it is under development. The purpose of this study was to test whether the relationship between leaf size and twig size is isometric or allometric, and to examine the relationship between plant allometric growth and life history strategies in the spectrum. • Methods Leaf and stem characters—including leaf and stem mass, total leaf area, individual leaf area, stem cross-sectional area, leaf number and stem length—at the twig level for 59 woody species were investigated along an altitudinal gradient on Changbaishan Mountain in the temperate zone of China. The environmental gradient ranges from temperate broad-leaved mixed forest at low altitude, to conifer forest at middle altitude, and to sub-alpine birch forest at high altitude. The scaling relationships between stem cross-sectional area and stem mass, stem mass and leaf mass, and leaf mass and leaf area at the twig level were simultaneously determined. • Key Results Twig cross-sectional area was found to have invariant allometric scaling relationships with the stem mass, leaf mass, total leaf area and individual leaf area, all with common slopes being significantly larger than 1, for three altitudinal-zoned vegetation types under investigation. However, leaf mass was found to be isometrically related to stem mass and leaf area along the environmental gradient. Based on the predictions of previous models, the exponent value of the relationship between twig cross-sectional area and total leaf area can be inferred to be 1·5, which falls between the confidence intervals of the relationship at each altitude, and between the confidence intervals of the common slope value (1·17–1·56) of this study. This invariant scaling relationship is assumed to result from the fractural network and/or developmental constraints of plants. The allometric constants (y-intercepts) of the

  12. Algorithm for retrieving vegetative canopy and leaf parameters from multi- and hyperspectral imagery

    NASA Astrophysics Data System (ADS)

    Borel, Christoph

    2009-05-01

    In recent years hyper-spectral data has been used to retrieve information about vegetative canopies such as leaf area index and canopy water content. For the environmental scientist these two parameters are valuable, but there is potentially more information to be gained as high spatial resolution data becomes available. We developed an Amoeba (Nelder-Mead or Simplex) based program to invert a vegetative canopy radiosity model coupled with a leaf (PROSPECT5) reflectance model and modeled for the background reflectance (e.g. soil, water, leaf litter) to a measured reflectance spectrum. The PROSPECT5 leaf model has five parameters: leaf structure parameter Nstru, chlorophyll a+b concentration Cab, carotenoids content Car, equivalent water thickness Cw and dry matter content Cm. The canopy model has two parameters: total leaf area index (LAI) and number of layers. The background reflectance model is either a single reflectance spectrum from a spectral library() derived from a bare area pixel on an image or a linear mixture of soil spectra. We summarize the radiosity model of a layered canopy and give references to the leaf/needle models. The method is then tested on simulated and measured data. We investigate the uniqueness, limitations and accuracy of the retrieved parameters on canopy parameters (low, medium and high leaf area index) spectral resolution (32 to 211 band hyperspectral), sensor noise and initial conditions.

  13. Leaf Extraction and Analysis Framework Graphical User Interface: Segmenting and Analyzing the Structure of Leaf Veins and Areoles1[W][OA

    PubMed Central

    Price, Charles A.; Symonova, Olga; Mileyko, Yuriy; Hilley, Troy; Weitz, Joshua S.

    2011-01-01

    Interest in the structure and function of physical biological networks has spurred the development of a number of theoretical models that predict optimal network structures across a broad array of taxonomic groups, from mammals to plants. In many cases, direct tests of predicted network structure are impossible given the lack of suitable empirical methods to quantify physical network geometry with sufficient scope and resolution. There is a long history of empirical methods to quantify the network structure of plants, from roots, to xylem networks in shoots and within leaves. However, with few exceptions, current methods emphasize the analysis of portions of, rather than entire networks. Here, we introduce the Leaf Extraction and Analysis Framework Graphical User Interface (LEAF GUI), a user-assisted software tool that facilitates improved empirical understanding of leaf network structure. LEAF GUI takes images of leaves where veins have been enhanced relative to the background, and following a series of interactive thresholding and cleaning steps, returns a suite of statistics and information on the structure of leaf venation networks and areoles. Metrics include the dimensions, position, and connectivity of all network veins, and the dimensions, shape, and position of the areoles they surround. Available for free download, the LEAF GUI software promises to facilitate improved understanding of the adaptive and ecological significance of leaf vein network structure. PMID:21057114

  14. Leaf economics of evergreen and deciduous tree species along an elevational gradient in a subtropical mountain

    PubMed Central

    Bai, Kundong; He, Chengxin; Wan, Xianchong; Jiang, Debing

    2015-01-01

    The ecophysiological mechanisms underlying the pattern of bimodal elevational distribution of evergreen tree species remain incompletely understood. Here we used leaf economics spectrum (LES) theory to explain such patterns. We measured leaf economic traits and constructed an LES for the co-existing 19 evergreen and 15 deciduous species growing in evergreen broad-leaved forest at low elevation, beech-mixed forest at middle elevation and hemlock-mixed forest at high elevation in Mao'er Mountain, Guangxi, Southern China (25°50′N, 110°49′E). Leaf economic traits presented low but significant phylogenetic signal, suggesting trait similarity between closely related species. After considering the effects of phylogenetic history, deciduous species in general showed a more acquisitive leaf strategy with a higher ratio of leaf water to dry mass, higher leaf nitrogen and phosphorous contents, higher photosynthetic and respiratory rates and greater photosynthetic nitrogen-use efficiency. In contrast, evergreen species exhibited a more conservative leaf strategy with higher leaf mass per area, greater construction costs and longer leaf life span. With the elevation-induced decreases of temperature and soil fertility, both evergreen and deciduous species showed greater resource conservation, suggesting the increasing importance of environmental filtering to community assembly with increasing elevation. We found close inter-specific correlations between leaf economic traits, suggesting that there are strong genetic constraints limiting the independent evolution of LES traits. Phylogenetic signal increased with decreasing evolutionary rate across leaf economic traits, suggesting that genetic constraints are important for the process of trait evolution. We found a significantly positive relationship between primary axis species score (PASS) distance and phylogenetic distance across species pairs and an increasing average PASS distance between evergreen and deciduous species

  15. Leaf economics of evergreen and deciduous tree species along an elevational gradient in a subtropical mountain.

    PubMed

    Bai, Kundong; He, Chengxin; Wan, Xianchong; Jiang, Debing

    2015-01-01

    The ecophysiological mechanisms underlying the pattern of bimodal elevational distribution of evergreen tree species remain incompletely understood. Here we used leaf economics spectrum (LES) theory to explain such patterns. We measured leaf economic traits and constructed an LES for the co-existing 19 evergreen and 15 deciduous species growing in evergreen broad-leaved forest at low elevation, beech-mixed forest at middle elevation and hemlock-mixed forest at high elevation in Mao'er Mountain, Guangxi, Southern China (25°50'N, 110°49'E). Leaf economic traits presented low but significant phylogenetic signal, suggesting trait similarity between closely related species. After considering the effects of phylogenetic history, deciduous species in general showed a more acquisitive leaf strategy with a higher ratio of leaf water to dry mass, higher leaf nitrogen and phosphorous contents, higher photosynthetic and respiratory rates and greater photosynthetic nitrogen-use efficiency. In contrast, evergreen species exhibited a more conservative leaf strategy with higher leaf mass per area, greater construction costs and longer leaf life span. With the elevation-induced decreases of temperature and soil fertility, both evergreen and deciduous species showed greater resource conservation, suggesting the increasing importance of environmental filtering to community assembly with increasing elevation. We found close inter-specific correlations between leaf economic traits, suggesting that there are strong genetic constraints limiting the independent evolution of LES traits. Phylogenetic signal increased with decreasing evolutionary rate across leaf economic traits, suggesting that genetic constraints are important for the process of trait evolution. We found a significantly positive relationship between primary axis species score (PASS) distance and phylogenetic distance across species pairs and an increasing average PASS distance between evergreen and deciduous species with

  16. Isotopic characteristics of canopies in simulated leaf assemblages

    NASA Astrophysics Data System (ADS)

    Graham, Heather V.; Patzkowsky, Mark E.; Wing, Scott L.; Parker, Geoffrey G.; Fogel, Marilyn L.; Freeman, Katherine H.

    2014-11-01

    The geologic history of closed-canopy forests is of great interest to paleoecologists and paleoclimatologists alike. Closed canopies have pronounced effects on local, continental and global rainfall and temperature patterns. Although evidence for canopy closure is difficult to reconstruct from the fossil record, the characteristic isotope gradients of the "canopy effect" could be preserved in leaves and proxy biomarkers. To assess this, we employed new carbon isotopic data for leaves collected in diverse light environments within a deciduous, temperate forest (Maryland, USA) and for leaves from a perennially closed canopy, moist tropical forest (Bosque Protector San Lorenzo, Panamá). In the tropical forest, leaf carbon isotope values range 10‰, with higher δ13Cleaf values occurring both in upper reaches of the canopy, and with higher light exposure and lower humidity. Leaf fractionation (Δleaf) varied negatively with height and light and positively with humidity. Vertical 13C enrichment in leaves largely reflects changes in Δleaf, and does not trend with δ13C of CO2 within the canopy. At the site in Maryland, leaves express a more modest δ13C range (∼6‰), with a clear trend that follows both light and leaf height. Using a model we simulate leaf assemblage isotope patterns from canopy data binned by elevation. The re-sampling (bootstrap) model determined both the mean and range of carbon isotope values for simulated leaf assemblages ranging in size from 10 to over 1000 leaves. For the tropical forest data, the canopy's isotope range is captured with 50 or more randomly sampled leaves. Thus, with a sufficient number of fossil leaves it is possible to distinguish isotopic gradients in an ancient closed canopy forest from those in an open forest. For very large leaf assemblages, mean isotopic values approximate the δ13C of carbon contributed by leaves to soil and are similar to observed δ13Clitter values at forested sites within Panamá, including the

  17. 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.

  18. 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

  19. 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.

  20. 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...

  1. 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...

  2. 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...

  3. 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...

  4. 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...

  5. Correlated evolution of stem and leaf hydraulic traits in Pereskia (Cactaceae).

    PubMed

    Edwards, Erika J

    2006-01-01

    Recent studies have demonstrated significant correlations between stem and leaf hydraulic properties when comparing across species within ecological communities. This implies that these traits are co-evolving, but there have been few studies addressing plant water relations within an explicitly evolutionary framework. This study tests for correlated evolution among a suite of plant water-use traits and environmental parameters in seven species of Pereskia (Cactaceae), using phylogenetically independent contrasts. There were significant evolutionary correlations between leaf-specific xylem hydraulic conductivity, Huber Value, leaf stomatal pore index, leaf venation density and leaf size, but none of these traits appeared to be correlated with environmental water availability; only two water relations traits - mid-day leaf water potentials and photosynthetic water use efficiency - correlated with estimates of moisture regime. In Pereskia, it appears that many stem and leaf hydraulic properties thought to be critical to whole-plant water use have not evolved in response to habitat shifts in water availability. This may be because of the extremely conservative stomatal behavior and particular rooting strategy demonstrated by all Pereskia species investigated. These results highlight the need for a lineage-based approach to understand the relative roles of functional traits in ecological adaptation. PMID:17083678

  6. Measuring and modeling the backscattering cross section of a leaf

    NASA Technical Reports Server (NTRS)

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

    1987-01-01

    Leaves are a significant feature of any vegetation canopy, and for remote sensing purposes it is important to develop an effective model for predicting the scattering from a leaf. From measurements of the X band backscattering cross section of a coleus leaf in varying stages of dryness, it is shown that a uniform resistive sheet constitutes such a model for a planar leaf. The scattering is determined by the (complex) resistivity which is, in turn, entirely specified by the gravimetric moisture content of the leaf. Using an available asymptotic expression for the scattering from a rectangular resistive plate which includes, as a special case, a metallic plate whose resistivity is zero, the computed backscattering cross sections for both principal polarizations are found to be in excellent agreement with data measured for rectangular sections of leaves with different moisture contents. If the resistivity is sufficiently large, the asymptotic expressions do not differ significantly from the physical optics ones, and for naturally shaped leaves as well as rectangular sections, the physical optics approximation in conjunction with the resistive sheet model faithfully reproduces the dominant feataures of the scattering patterns under all moisture conditions.

  7. 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...

  8. 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...

  9. 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...

  10. 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...

  11. 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...

  12. 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...

  13. 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...

  14. 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...

  15. 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...

  16. 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...

  17. 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...

  18. 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...

  19. Predicting tree water use and drought tolerance from leaf traits in the Los Angeles urban ecosystem

    NASA Astrophysics Data System (ADS)

    John, G. P.; Scoffoni, C.; Sack, L.

    2013-12-01

    Urban green space provides a suite of valuable ecosystem services. In semiarid systems, like Los Angeles, trees rely primarily on irrigation water for transpiration. Managers may need to reduce irrigation associated with urban trees given climate change, urban expansion, and the steady decrease in available freshwater. While leaf and whole plant water relations have been extensively studied, we are only now gaining a detailed understanding of diverse leaf anatomical designs, and their use for predicting physiology and water use at landscape scale. For 50 diverse urban species, we quantified leaf anatomical and physiological traits important to tree drought tolerance and water use efficiency including turgor loss point, vein architecture, cellular anatomy, leaf mass per unit area, and petiole and leaf dimensions. We hypothesized detailed relationships to develop models relating leaf functional traits to tree water relations. These models provide key insights regarding the role of anatomical designs in leaf stress tolerance and water use efficiency. Additionally we predicted how traits measured at the leaf level would scale with existing data for individuals at the whole plant level. We tested our predictions by determining correlations between leaf level anatomical traits and drought tolerance. Additionally, we determined correlations between functional traits, physiology and water use, and the climate of origin for the urban species. Leaf level measurements will be valuable for rapid estimation of more difficult to measure whole plant water relations traits important at the landscape scale. The Los Angeles urban ecosystem can serve as a model for other semiarid system and provide more informed system wide water conservation strategies.

  20. Transpiration and Leaf Temperature. Physical Processes in Terrestrial and Aquatic Ecosystems, Transport Processes.

    ERIC Educational Resources Information Center

    Gates, David M.

    These materials were designed to be used by life science students for instruction in the application of physical theory to ecosystem operation. Most modules contain computer programs which are built around a particular application of a physical process. This report introduces two models of the thermal energy budget of a leaf. Typical values for…

  1. Antioxidant, genotoxic and antigenotoxic activities of daphne gnidium leaf extracts

    PubMed Central

    2012-01-01

    Background Plants play a significant role in maintaining human health and improving the quality of human life. They serve humans well as valuable components of food, as well as in cosmetics, dyes, and medicines. In fact, many plant extracts prepared from plants have been shown to exert biological activity in vitro and in vivo. The present study explored antioxidant and antigenotoxic effects of Daphne gnidium leaf extracts. Methods The genotoxic potential of petroleum ether, chloroform, ethyl acetate, methanol and total oligomer flavonoid (TOF) enriched extracts from leaves of Daphne gnidium, was assessed using Escherichia coli PQ37. Likewise, the antigenotoxicity of the same extracts was tested using the “SOS chromotest test”. Antioxidant activities were studied using non enzymatic and enzymatic method: NBT/Riboflavine and xantine oxidase. Results None of the different extracts produced a genotoxic effect, except TOF extract at the lowest tested dose. Our results showed that D. gnidium leaf extracts possess an antigenotoxic effect against the nitrofurantoin a mutagen of reference. Ethyl acetate and TOF extracts were the most effective in inhibiting xanthine oxidase activity. While, methanol extract was the most potent superoxide scavenger when tested with the NBT/Riboflavine assay. Conclusions The present study has demonstrated that D. gnidium leaf extract possess antioxidant and antigenotoxic effects. These activities could be ascribed to compounds like polyphenols and flavonoid. Further studies are required to isolate the active molecules. PMID:22974481

  2. Association of a recombinant Cotton leaf curl Bangalore virus with yellow vein and leaf curl disease of okra in India.

    PubMed

    Venkataravanappa, V; Lakshminarayana Reddy, C N; Devaraju, A; Jalali, Salil; Krishna Reddy, M

    2013-09-01

    A begomovirus isolate (OY136A) collected from okra plants showing upward leaf curling, vein clearing, vein thickening and yellowing symptoms from Bangalore rural district, Karnataka, India was characterized. The sequence comparisons revealed that, this virus isolate share highest nucleotide identity with isolates of Cotton leaf curl Bangalore virus (CLCuBV) (AY705380) (92.8 %) and Okra enation leaf curl virus (81.1-86.2 %). This is well supported by phylogentic analysis showing, close clustering of the virus isolate with CLCuBV. With this data, based on the current taxonomic criteria for the genus Begomovirus, the present virus isolate is classified as a new strain of CLCuBV, for which CLCuBV-[India: Bangalore: okra: 2006] additional descriptor is proposed. The betasatellite (KC608158) associated with the virus is having more than 95 % sequence similarity with the cotton leaf curl betasatellites (CLCuB) available in the GenBank.The recombination analysis suggested, emergence of this new strain of okra infecting begomovirus might have been from the exchange of genetic material between BYVMV and CLCuMuV. The virus was successfully transmitted by whitefly and grafting. The host range of the virus was shown to be very narrow and limited to two species in the family Malvaceae, okra (Abelmoschus esculentus) and hollyhock (Althaea rosea), and four in the family Solanaceae. PMID:24426275

  3. Molecular Characterization of Tomato leaf curl Palampur virus and Pepper leaf curl betasatellite Naturally Infecting Pumpkin (Cucurbita moschata) in India.

    PubMed

    Namrata, Jaiswal; Saritha, R K; Datta, D; Singh, M; Dubey, R S; Rai, A B; Rai, M

    2010-10-01

    Pumpkin cultivation in India is affected by severe incidence of a yellow vein mosaic disease. Tomato leaf curl New Delhi virus and Squash leaf curl China virus are known to be associated with this disease in India. We were able to identify a third begomovirus-Tomato leaf curl Palampur virus (ToLCPMV), from pumpkin showing typical symptoms of the disease at Varanasi based on the sequence of complete DNA-A genome of the virus. The complete DNA-A sequence of the virus shared more than 99% sequence identity with other ToLCPMV isolates available in the GenBank and clustered with them in the phylogenetic analysis. This betasatellite amplified from the same infected sample has been identified as Pepper leaf curl betasatellite (PepLCB) which also infects chilli in India. There was 92% sequence identity between the two isolates. This is the first report of natural infection of ToLCPMV on pumpkin and association of PepLCB with yellow vein mosaic disease of pumpkin in India. PMID:23637491

  4. 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.

  5. 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

  6. “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

  7. 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

  8. 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.

  9. Integrating sphere transmissometer for field measurement of leaf transmittance

    NASA Astrophysics Data System (ADS)

    Vanderbilt, V. C.; Dewitt, D. P.; Robinson, B. F.

    1987-12-01

    A simple field-rated transmissometer is described for rapidly determining the normal hemispherical transmittance T(0 deg, 2 pi) of leaves measured in situ in the four Landsat wavelength bands. The transmissometer requires direct solar illumination of the leaf sample. It collects the transmitted light with an integrating sphere and measures the collected light using a commercially available radiometer. The transmittances determined by the transmissometer are comparable with those measured by a labortory spectrophotometer with an integrating sphere attachment.

  10. Drought-Induced Leaf Proteome Changes in Switchgrass Seedlings

    PubMed Central

    Ye, Zhujia; Sangireddy, Sasikiran; Okekeogbu, Ikenna; Zhou, Suping; Yu, Chih-Li; Hui, Dafeng; Howe, Kevin J.; Fish, Tara; Thannhauser, Theodore W.

    2016-01-01

    Switchgrass (Panicum virgatum) is a perennial crop producing deep roots and thus highly tolerant to soil water deficit conditions. However, seedling establishment in the field is very susceptible to prolonged and periodic drought stress. In this study, a “sandwich” system simulating a gradual water deletion process was developed. Switchgrass seedlings were subjected to a 20-day gradual drought treatment process when soil water tension was increased to 0.05 MPa (moderate drought stress) and leaf physiological properties had expressed significant alteration. Drought-induced changes in leaf proteomes were identified using the isobaric tags for relative and absolute quantitation (iTRAQ) labeling method followed by nano-scale liquid chromatography mass spectrometry (nano-LC-MS/MS) analysis. Additionally, total leaf proteins were processed using a combinatorial library of peptide ligands to enrich for lower abundance proteins. Both total proteins and those enriched samples were analyzed to increase the coverage of the quantitative proteomics analysis. A total of 7006 leaf proteins were identified, and 257 (4% of the leaf proteome) expressed a significant difference (p < 0.05, fold change <0.6 or >1.7) from the non-treated control to drought-treated conditions. These proteins are involved in the regulation of transcription and translation, cell division, cell wall modification, phyto-hormone metabolism and signaling transduction pathways, and metabolic pathways of carbohydrates, amino acids, and fatty acids. A scheme of abscisic acid (ABA)-biosynthesis and ABA responsive signal transduction pathway was reconstructed using these drought-induced significant proteins, showing systemic regulation at protein level to deploy the respective mechanism. Results from this study, in addition to revealing molecular responses to drought stress, provide a large number of proteins (candidate genes) that can be employed to improve switchgrass seedling growth and establishment under

  11. Drought-Induced Leaf Proteome Changes in Switchgrass Seedlings.

    PubMed

    Ye, Zhujia; Sangireddy, Sasikiran; Okekeogbu, Ikenna; Zhou, Suping; Yu, Chih-Li; Hui, Dafeng; Howe, Kevin J; Fish, Tara; Thannhauser, Theodore W

    2016-01-01

    Switchgrass (Panicum virgatum) is a perennial crop producing deep roots and thus highly tolerant to soil water deficit conditions. However, seedling establishment in the field is very susceptible to prolonged and periodic drought stress. In this study, a "sandwich" system simulating a gradual water deletion process was developed. Switchgrass seedlings were subjected to a 20-day gradual drought treatment process when soil water tension was increased to 0.05 MPa (moderate drought stress) and leaf physiological properties had expressed significant alteration. Drought-induced changes in leaf proteomes were identified using the isobaric tags for relative and absolute quantitation (iTRAQ) labeling method followed by nano-scale liquid chromatography mass spectrometry (nano-LC-MS/MS) analysis. Additionally, total leaf proteins were processed using a combinatorial library of peptide ligands to enrich for lower abundance proteins. Both total proteins and those enriched samples were analyzed to increase the coverage of the quantitative proteomics analysis. A total of 7006 leaf proteins were identified, and 257 (4% of the leaf proteome) expressed a significant difference (p < 0.05, fold change <0.6 or >1.7) from the non-treated control to drought-treated conditions. These proteins are involved in the regulation of transcription and translation, cell division, cell wall modification, phyto-hormone metabolism and signaling transduction pathways, and metabolic pathways of carbohydrates, amino acids, and fatty acids. A scheme of abscisic acid (ABA)-biosynthesis and ABA responsive signal transduction pathway was reconstructed using these drought-induced significant proteins, showing systemic regulation at protein level to deploy the respective mechanism. Results from this study, in addition to revealing molecular responses to drought stress, provide a large number of proteins (candidate genes) that can be employed to improve switchgrass seedling growth and establishment under soil

  12. Relationships Between Photosynthetic Activity and Silica Accumulation with Ages of Leaf in Sasa veitchii (Poaceae, Bambusoideae)

    PubMed Central

    Motomura, Hiroyuki; Hikosaka, Kouki; Suzuki, Mitsuo

    2008-01-01

    Background and Aims Bamboos have long-lived, evergreen leaves that continue to accumulate silica throughout their life. Silica accumulation has been suggested to suppress their photosynthetic activity. However, nitrogen content per unit leaf area (Narea), an important determinant of maximum photosynthetic capacity per unit leaf area (Pmax), decreases as leaves age and senescence. In many species, Pmax decreases in parallel with the leaf nitrogen content. It is hypothesized that if silica accumulation affects photosynthesis, then Pmax would decrease faster than Narea, leading to a decrease in photosynthetic rate per unit leaf nitrogen (photosynthetic nitrogen use efficiency, PNUE) with increasing silica content in leaves. Methods The hypothesis was tested in leaves of Sasa veitchii, which have a life span of 2 years and accumulate silica up to 41 % of dry mass. Seasonal changes in Pmax, stomatal conductance, Narea and silica content were measured for leaves of different ages. Key Results Although Pmax and PNUE were negatively related with silica content across leaves of different ages, the relationship between PNUE and silica differed depending on leaf age. In second-year leaves, PNUE was almost constant although there was a large increase in silica content, suggesting that leaf nitrogen was a primary factor determining the variation in Pmax and that silica accumulation did not affect photosynthesis. PNUE was strongly and negatively correlated with silica content in third-year leaves, suggesting that silica accumulation affected photosynthesis of older leaves. Conclusions Silica accumulation in long-lived leaves of bamboo did not affect photosynthesis when the silica concentration of a leaf was less than 25 % of dry mass. Silica may be actively transported to epidermal cells rather than chlorenchyma cells, avoiding inhibition of CO2 diffusion from the intercellular space to chloroplasts. However, in older leaves with a larger silica content, silica was also

  13. 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,...

  14. 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,...

  15. 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,...

  16. 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,...

  17. 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,...

  18. 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,...

  19. 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,...

  20. 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,...

  1. 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

  2. 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...

  3. 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.

  4. 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)

  5. 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

  6. 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

  7. 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

  8. 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

  9. Changes in Chloroplast mRNA Stability during Leaf Development.

    PubMed Central

    Klaff, P; Gruissem, W

    1991-01-01

    During spinach leaf development, chloroplast-encoded mRNAs accumulate to different steady-state levels. Their relative transcription rates alone, however, cannot account for the changes in mRNA amount. In this study, we examined the importance of mRNA stability for the regulation of plastid mRNA accumulation using an in vivo system to measure mRNA decay in intact leaves by inhibiting transcription with actinomycin D. Decay of psbA and rbcL mRNAs was assayed in young and mature leaves. The psbA mRNA half-life was increased more than twofold in mature leaves compared with young leaves, whereas rbcL mRNA decayed with a similar relative half-life at both leaf developmental stages. The direct in vivo measurements demonstrated that differential mRNA stability in higher plant plastids can account for differences in mRNA accumulation during leaf development. The role of polysome association in mRNA decay was also investigated. Using organelle-specific translation inhibitors that force mRNAs into a polysome-bound state or deplete mRNAs of ribosomes, we measured mRNA decay in vivo in either state. The results showed that rbcL and psbA mRNAs are less stable when bound to polysomes relative to the polysome-depleted mRNAs and that their stabilities are differentially affected by binding to polysomes. The results suggested that ribosome binding and/or translation of the psbA and rbcL mRNAs may function to modulate the rate of their decay in chloroplasts. PMID:12324602

  10. 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

  11. Life's Still Lifes

    NASA Astrophysics Data System (ADS)

    McIntosh, Harold V.

    The de Bruijn diagram describing those decompositions of the neighborhoods of a one dimensional cellular automaton which conform to predetermined requirements of periodicity and translational symmetry shows how to construct extended configurations satisfying the same requirements. Similar diagrams, formed by stages, describe higher dimensional automata, although they become more laborious to compute with increasing neighborhood size. The procedure is illustrated by computing some still lifes for Conway's game of Life, a widely known two dimensional cellular automaton. This paper is written in September 10, 1988.

  12. Weak coordination among petiole, leaf, vein, and gas-exchange traits across Australian angiosperm species and its possible implications.

    PubMed

    Gleason, Sean M; Blackman, Chris J; Chang, Yvonne; Cook, Alicia M; Laws, Claire A; Westoby, Mark

    2016-01-01

    Close coordination between leaf gas exchange and maximal hydraulic supply has been reported across diverse plant life forms. However, it has also been suggested that this relationship may become weak or break down completely within the angiosperms. We examined coordination between hydraulic, leaf vein, and gas-exchange traits across a diverse group of 35 evergreen Australian angiosperms, spanning a large range in leaf structure and habitat. Leaf-specific conductance was calculated from petiole vessel anatomy and was also measured directly using the rehydration technique. Leaf vein density (thought to be a determinant of gas exchange rate), maximal stomatal conductance, and net CO 2 assimilation rate were also measured for most species (n = 19-35). Vein density was not correlated with leaf-specific conductance (either calculated or measured), stomatal conductance, nor maximal net CO 2 assimilation, with r (2) values ranging from 0.00 to 0.11, P values from 0.909 to 0.102, and n values from 19 to 35 in all cases. Leaf-specific conductance calculated from petiole anatomy was weakly correlated with maximal stomatal conductance (r (2) = 0.16; P = 0.022; n = 32), whereas the direct measurement of leaf-specific conductance was weakly correlated with net maximal CO 2 assimilation (r (2) = 0.21; P = 0.005; n = 35). Calculated leaf-specific conductance, xylem ultrastructure, and leaf vein density do not appear to be reliable proxy traits for assessing differences in rates of gas exchange or growth across diverse sets of evergreen angiosperms. PMID:26811791

  13. 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

  14. 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

  15. 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.

  16. 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

  17. 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

  18. 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

  19. 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.

  20. Genes Involved in the Evolution of Herbivory by a Leaf-Mining, Drosophilid Fly

    PubMed Central

    Whiteman, Noah K.; Gloss, Andrew D.; Sackton, Timothy B.; Groen, Simon C.; Humphrey, Parris T.; Lapoint, Richard T.; Sønderby, Ida E.; Halkier, Barbara A.; Kocks, Christine; Ausubel, Frederick M.; Pierce, Naomi E.

    2012-01-01

    Herbivorous insects are among the most successful radiations of life. However, we know little about the processes underpinning the evolution of herbivory. We examined the evolution of herbivory in the fly, Scaptomyza flava, whose larvae are leaf miners on species of Brassicaceae, including the widely studied reference plant, Arabidopsis thaliana (Arabidopsis). Scaptomyza flava is phylogenetically nested within the paraphyletic genus Drosophila, and the whole genome sequences available for 12 species of Drosophila facilitated phylogenetic analysis and assembly of a transcriptome for S. flava. A time-calibrated phylogeny indicated that leaf mining in Scaptomyza evolved between 6 and 16 million years ago. Feeding assays showed that biosynthesis of glucosinolates, the major class of antiherbivore chemical defense compounds in mustard leaves, was upregulated by S. flava larval feeding. The presence of glucosinolates in wild-type (WT) Arabidopsis plants reduced S. flava larval weight gain and increased egg–adult development time relative to flies reared in glucosinolate knockout (GKO) plants. An analysis of gene expression differences in 5-day-old larvae reared on WT versus GKO plants showed a total of 341 transcripts that were differentially regulated by glucosinolate uptake in larval S. flava. Of these, approximately a third corresponded to homologs of Drosophila melanogaster genes associated with starvation, dietary toxin-, heat-, oxidation-, and aging-related stress. The upregulated transcripts exhibited elevated rates of protein evolution compared with unregulated transcripts. The remaining differentially regulated transcripts also contained a higher proportion of novel genes than the unregulated transcripts. Thus, the transition to herbivory in Scaptomyza appears to be coupled with the evolution of novel genes and the co-option of conserved stress-related genes. PMID:22813779

  1. 75 Easy Life Science Demonstrations. Teacher Book.

    ERIC Educational Resources Information Center

    Kardos, Thomas

    This book is a collection of life science classroom demonstrations. Explanations that review key concepts are included. Topics are: stimulus and response; gravitropism; phototropism; living organisms; carbon dioxide; gases emitted by plants; greenhouse effect; stomata; transpiration; leaf skeletons; seed growth; water evaporation in plants; carbon…

  2. ClearedLeavesDB: an online database of cleared plant leaf images

    PubMed Central

    2014-01-01

    Background Leaf vein networks are critical to both the structure and function of leaves. A growing body of recent work has linked leaf vein network structure to the physiology, ecology and evolution of land plants. In the process, multiple institutions and individual researchers have assembled collections of cleared leaf specimens in which vascular bundles (veins) are rendered visible. In an effort to facilitate analysis and digitally preserve these specimens, high-resolution images are usually created, either of entire leaves or of magnified leaf subsections. In a few cases, collections of digital images of cleared leaves are available for use online. However, these collections do not share a common platform nor is there a means to digitally archive cleared leaf images held by individual researchers (in addition to those held by institutions). Hence, there is a growing need for a digital archive that enables online viewing, sharing and disseminating of cleared leaf image collections held by both institutions and individual researchers. Description The Cleared Leaf Image Database (ClearedLeavesDB), is an online web-based resource for a community of researchers to contribute, access and share cleared leaf images. ClearedLeavesDB leverages resources of large-scale, curated collections while enabling the aggregation of small-scale collections within the same online platform. ClearedLeavesDB is built on Drupal, an open source content management platform. It allows plant biologists to store leaf images online with corresponding meta-data, share image collections with a user community and discuss images and collections via a common forum. We provide tools to upload processed images and results to the database via a web services client application that can be downloaded from the database. Conclusions We developed ClearedLeavesDB, a database focusing on cleared leaf images that combines interactions between users and data via an intuitive web interface. The web interface

  3. Spectral measurements at different spatial scales in potato: relating leaf, plant and canopy nitrogen status

    NASA Astrophysics Data System (ADS)

    Jongschaap, Raymond E. E.; Booij, Remmie

    2004-09-01

    Chlorophyll contents in vegetation depend on soil nitrogen availability and on crop nitrogen uptake, which are important management factors in arable farming. Crop nitrogen uptake is important, as nitrogen is needed for chlorophyll formation, which is important for photosynthesis, i.e. the conversion of absorbed radiance into plant biomass. The objective of this study was to estimate leaf and canopy nitrogen contents by near and remote sensing observations and to link observations at leaf, plant and canopy level. A theoretical base is presented for scaling-up leaf optical properties to whole plants and crops, by linking different optical recording techniques at leaf, plant and canopy levels through the integration of vertical nitrogen distribution. Field data come from potato experiments in The Netherlands in 1997 and 1998, comprising two potato varieties: Eersteling and Bintje, receiving similar nitrogen treatments (0, 100, 200 and 300 kg N ha -1) in varying application schemes to create differences in canopy nitrogen status during the growing season. Ten standard destructive field samplings were performed to follow leaf area index and crop dry weight evolution. Samples were analysed for inorganic nitrogen and total nitrogen contents. At sampling dates, spectral measurements were taken both at leaf level and at canopy level. At leaf level, an exponential relation between SPAD-502 readings and leaf organic nitrogen contents with a high correlation factor of 0.91 was found. At canopy level, an exponential relation between canopy organic nitrogen contents and red edge position ( λrep, nm) derived from reflectance measurements was found with a good correlation of 0.82. Spectral measurements (SPAD-502) at leaf level of a few square mm were related to canopy reflectance measurements (CropScan™) of approximately 0.44 m 2. Statistical regression techniques were used to optimise theoretical vertical nitrogen profiles that allowed scaling-up leaf chlorophyll measurements

  4. Plant development controls leaf area expansion in alfalfa plants competing for light

    PubMed Central

    Baldissera, Tiago Celso; Frak, Ela; Carvalho, Paulo Cesar de Faccio; Louarn, Gaëtan

    2014-01-01

    Background and Aims The growth of crops in a mixture is more variable and difficult to predict than that in pure stands. Light partitioning and crop leaf area expansion play prominent roles in explaining this variability. However, in many crops commonly grown in mixtures, including the forage species alfalfa, the sensitivity and relative importance of the physiological responses involved in the light modulation of leaf area expansion are still to be established. This study was designed to assess the relative sensitivity of primary shoot development, branching and individual leaf expansion in alfalfa in response to light availability. Methods Two experiments were carried out. The first studied isolated plants to assess the potential development of different shoot types and growth periods. The second consisted of manipulating the intensity of competition for light using a range of canopies in pure and mixed stands at two densities so as to evaluate the relative effects on shoot development, leaf growth, and plant and shoot demography. Key Results Shoot development in the absence of light competition was deterministic (constant phyllochrons of 32·5 °Cd and 48·2 °Cd for primary axes and branches, branching probability of 1, constant delay of 1·75 phyllochron before axillary bud burst) and identical irrespective of shoot type and growth/regrowth periods. During light competition experiments, changes in plant development explained most of the plant leaf area variations, with average leaf size contributing to a lesser extent. Branch development and the number of shoots per plant were the leaf area components most affected by light availability. Primary axis development and plant demography were only affected in situations of severe light competition. Conclusions Plant leaf area components differed with regard to their sensitivity to light competition. The potential shoot development model presented in this study could serve as a framework to integrate light responses

  5. 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

  6. 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.

  7. Rapid effects of nitrogen form on leaf morphogenesis in tobacco.

    PubMed

    Walch-Liu, P; Neumann, G; Bangerth, F; Engels, C

    2000-02-01

    Ammonium (NH4+) instead of nitrate (NO3-) as the nitrogen (N) source for tobacco (Nicotiana tabacum L.) cultivated in a pH-buffered nutrient solution resulted in decreased shoot and root biomass. Reduction of shoot fresh weight was mainly related to inhibition of leaf growth, which was already detectable after short-term NH4+ treatments of 24 h, and even at a moderate concentration level of 2 mM. Microscopic analysis of the epidermis of fully expanded leaves revealed a decrease in cell number (50%) and in cell size (30%) indicating that both cell division and cell elongation were affected by NH4+ application. Changes in various physiological parameters known to be associated with NH4(+)-induced growth depression were examined both in long-term and short-term experiments: the concentrations of total N, soluble sugars and starch as well as the osmotic potential, the apparent hydraulic conductivity and the rate of water uptake were not reduced by NH4+ treatments (duration 1-12 d), suggesting that leaf growth was neither limited by the availability of N and carbohydrates, nor by a lack of osmotica or water supply. Although the concentration of K+ in leaf press sap declined in expanding leaves by approximately 15% in response to NH4+ nutrition, limitation of mineral nutrients seems to be unlikely in view of the fast response of leaf growth at 24 h after the start of the NH4+ treatment. No inhibitory effects were observed when NH4+ and NO3- were applied simultaneously (each 1 mM) resulting in a NO3-/NH4+ net uptake ratio of 6:4. These findings suggest that the rapid inhibition of leaf growth was not primarily related to NH4+ toxicity, but to the lack of NO3(-)-supply. Growth inhibition of plants fed solely with NH4+ was associated with a 60% reduction of the zeatine + zeatine riboside (Z + ZR) cytokinin fraction in the xylem sap after 24 h. Furthermore Z + ZR levels declined to almost zero within the next 4 d after start of the NH4+ treatment. In contrast, the

  8. 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

  9. 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.

  10. 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...

  11. 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...

  12. 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,...

  13. 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,...

  14. 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...

  15. 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...

  16. 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...

  17. 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...

  18. 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...

  19. 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...

  20. 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...

  1. 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...

  2. 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...

  3. 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...

  4. 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...

  5. 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...

  6. 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…

  7. 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.

  8. 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.

  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. 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.

  15. 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.

  16. 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)

  17. 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)

  18. 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

  19. Stress optimization of leaf-spring crossed flexure pivots for an active Gurney flap mechanism

    NASA Astrophysics Data System (ADS)

    Freire Gómez, Jon; Booker, Julian D.; Mellor, Phil H.

    2015-04-01

    The EU's Green Rotorcraft programme is pursuing the development of a functional and airworthy Active Gurney Flap (AGF) for a full-scale helicopter rotor blade. Interest in the development of this `smart adaptive rotor blade' technology lies in its potential to provide a number of aerodynamic benefits, which would in turn translate into a reduction in fuel consumption and noise levels. The AGF mechanism selected employs leaf-spring crossed flexure pivots. These provide important advantages over bearings as they are not susceptible to seizing and do not require maintenance (i.e. lubrication or cleaning). A baseline design of this mechanism was successfully tested both in a fatigue rig and in a 2D wind tunnel environment at flight-representative deployment schedules. For full validation, a flight test would also be required. However, the severity of the in-flight loading conditions would likely compromise the mechanical integrity of the pivots' leaf-springs in their current form. This paper investigates the scope for stress reduction through three-dimensional shape optimization of the leaf-springs of a generic crossed flexure pivot. To this end, a procedure combining a linear strain energy formulation, a parametric leaf-spring profile definition and a series of optimization algorithms is employed. The resulting optimized leaf-springs are proven to be not only independent of the angular rotation at which the pivot operates, but also linearly scalable to leaf-springs of any length, minimum thickness and width. Validated using non-linear finite element analysis, the results show very significant stress reductions relative to pivots with constant cross section leaf-springs, of up to as much as 30% for the specific pivot configuration employed in the AGF mechanism. It is concluded that shape optimization offers great potential for reducing stress in crossed flexure pivots and, consequently, for extending their fatigue life and/or rotational range.

  20. 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

  1. 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

  2. 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.

  3. Preliminary results of Physiological plant growth modelling for human life support in space

    NASA Astrophysics Data System (ADS)

    Sasidharan L, Swathy; Dussap, Claude-Gilles; Hezard, Pauline

    2012-07-01

    Human life support is fundamental and crucial in any kind of space explorations. MELiSSA project of European Space Agency aims at developing a closed, artificial ecological life support system involving human, plants and micro organisms. Consuming carbon dioxide and water from the life support system, plants grow in one of the chambers and convert it into food and oxygen along with potable water. The environmental conditions, nutrient availability and its consumption of plants should be studied and necessarily modeled to predict the amount of food, oxygen and water with respect to the environmental changes and limitations. The reliability of a completely closed system mainly depends on the control laws and strategies used. An efficient control can occur, only if the system to control is itself well known, described and ideally if the responses of the system to environmental changes are predictable. In this aspect, the general structure of plant growth model has been designed together with physiological modelling.The physiological model consists of metabolic models of leaves, stem and roots, of which concern specific metabolisms of the associated plant parts. On the basis of the carbon source transport (eg. sucrose) through stem, the metabolic models (leaf and root) can be interconnected to each other and finally coupled to obtain the entire plant model. For the first step, leaf metabolic model network was built using stoichiometric, mass and energy balanced metabolic equations under steady state approach considering all necessary plant pathways for growth and maintenance of leaves. As the experimental data for lettuce plants grown in closed and controlled environmental chambers were available, the leaf metabolic model has been established for lettuce leaves. The constructed metabolic network is analyzed using known stoichiometric metabolic technique called metabolic flux analysis (MFA). Though, the leaf metabolic model alone is not sufficient to achieve the

  4. A New Method to Quantify the Isotopic Signature of Leaf Transpiration: Implications for Landscape-Scale Evapotranspiration Partitioning Studies

    NASA Astrophysics Data System (ADS)

    Wang, L.; Good, S. P.; Caylor, K. K.

    2010-12-01

    Characterizing the constituent components of evapotranspiration is crucial to better understand ecosystem-level water budgets and water use dynamics. Isotope based evapotranspiration partitioning methods are promising but their utility lies in the accurate estimation of the isotopic composition of underlying transpiration and evaporation. Here we report a new method to quantify the isotopic signature of leaf transpiration under field conditions. This method utilizes a commercially available laser-based isotope analyzer and a transparent leaf chamber, modified from Licor conifer leaf chamber. The method is based on the water mass balance in ambient air and leaf transpired air. We verified the method using “artificial leaves” and glassline extracted samples. The method provides a new and direct way to estimate leaf transpiration isotopic signatures and it has wide applications in ecology, hydrology and plant physiology.

  5. Effect of Habitat Conditions and Plant Traits on Leaf Damage in the Carduoideae Subfamily

    PubMed Central

    Münzbergová, Zuzana; Skuhrovec, Jiří

    2013-01-01

    Plant traits are the key factors that determine herbivore foraging selection. The traits serving as defense traits against herbivores represent a wide range of traits, such as chemical, physiological, morphological and life-history traits. While many studies considered plant defense traits at the within-species scale, much less is known from comparisons of a wide range of closely related species. The aim of this study was to identify factors responsible for the intensity of leaf damage in the Carduoideae subfamily of Asteraceae, which hosts many invasive species and thus is potential candidate plant species that could be controlled by biological control. Specifically, we wanted to see the relative importance of habitat characteristics, plant size and plants traits in determining the degree of folivory. The study identified several defense traits able to explain differences in herbivory between species after accounting for differences in the habitats in which the species occur and the plant size. Specifically, the most important traits were traits related to the quality of the leaf tissue expressed as the content of phosphorus, water and specific leaf area, which suggests that the leaf quality had a more important effect on the degree of herbivory than the presence of specific defense mechanisms such as spines and hair. Leaf quality is thus a candidate factor that drives herbivore choice when selecting which plant to feed on and should be considered when assessing the danger that a herbivore will switch hosts when introduced to a new range. PMID:23717643

  6. Error analysis of leaf area estimates made from allometric regression models

    NASA Technical Reports Server (NTRS)

    Feiveson, A. H.; Chhikara, R. S.

    1986-01-01

    Biological net productivity, measured in terms of the change in biomass with time, affects global productivity and the quality of life through biochemical and hydrological cycles and by its effect on the overall energy balance. Estimating leaf area for large ecosystems is one of the more important means of monitoring this productivity. For a particular forest plot, the leaf area is often estimated by a two-stage process. In the first stage, known as dimension analysis, a small number of trees are felled so that their areas can be measured as accurately as possible. These leaf areas are then related to non-destructive, easily-measured features such as bole diameter and tree height, by using a regression model. In the second stage, the non-destructive features are measured for all or for a sample of trees in the plots and then used as input into the regression model to estimate the total leaf area. Because both stages of the estimation process are subject to error, it is difficult to evaluate the accuracy of the final plot leaf area estimates. This paper illustrates how a complete error analysis can be made, using an example from a study made on aspen trees in northern Minnesota. The study was a joint effort by NASA and the University of California at Santa Barbara known as COVER (Characterization of Vegetation with Remote Sensing).

  7. Diversity, Mutation and Recombination Analysis of Cotton Leaf Curl Geminiviruses

    PubMed Central

    Saleem, Huma; Nahid, Nazia; Shakir, Sara; Ijaz, Sehrish; Murtaza, Ghulam; Khan, Asif Ali; Mubin, Muhammad; Nawaz-ul-Rehman, Muhammad Shah

    2016-01-01

    The spread of cotton leaf curl disease in China, India and Pakistan is a recent phenomenon. Analysis of available sequence data determined that there is a substantial diversity of cotton-infecting geminiviruses in Pakistan. Phylogenetic analyses indicated that recombination between two major groups of viruses, cotton leaf curl Multan virus (CLCuMuV) and cotton leaf curl Kokhran virus (CLCuKoV), led to the emergence of several new viruses. Recombination detection programs and phylogenetic analyses showed that CLCuMuV and CLCuKoV are highly recombinant viruses. Indeed, CLCuKoV appeared to be a major donor virus for the coat protein (CP) gene, while CLCuMuV donated the Rep gene in the majority of recombination events. Using recombination free nucleotide datasets the substitution rates for CP and Rep genes were determined. We inferred similar nucleotide substitution rates for the CLCuMuV-Rep gene (4.96X10-4) and CLCuKoV-CP gene (2.706X10-4), whereas relatively higher substitution rates were observed for CLCuMuV-CP and CLCuKoV-Rep genes. The combination of sequences with equal and relatively low substitution rates, seemed to result in the emergence of viral isolates that caused epidemics in Pakistan and India. Our findings also suggest that CLCuMuV is spreading at an alarming rate, which can potentially be a threat to cotton production in the Indian subcontinent. PMID:26963635

  8. 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

  9. 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

  10. 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

  11. Leaf processing behaviour in Atta leafcutter ants: 90% of leaf cutting takes place inside the nest, and ants select pieces that require less cutting.

    PubMed

    Garrett, Ryan W; Carlson, Katherine A; Goggans, Matthew Scott; Nesson, Michael H; Shepard, Christopher A; Schofield, Robert M S

    2016-01-01

    Leafcutter ants cut trimmings from plants, carry them to their underground nests and cut them into smaller pieces before inoculating them with a fungus that serves as a primary food source for the colony. Cutting is energetically costly, so the amount of cutting is important in understanding foraging energetics. Estimates of the cutting density, metres of cutting per square metre of leaf, were made from samples of transported leaf cuttings and of fungal substrate from field colonies of Atta cephalotes and Atta colombica. To investigate cutting inside the nest, we made leaf-processing observations of our laboratory colony, A. cephalotes. We did not observe the commonly reported reduction of the leaf fragments into a pulp, which would greatly increase the energy cost of processing. Video clips of processing behaviours, including behaviours that have not previously been described, are linked. An estimated 2.9 (±0.3) km of cutting with mandibles was required to reduce a square metre of leaf to fungal substrate. Only about 12% (±1%) of this cutting took place outside of the nest. The cutting density and energy cost is lower for leaf material with higher ratios of perimeter to area, so we tested for, and found that the laboratory ants had a preference for leaves that were pre-cut into smaller pieces. Estimates suggest that the energy required to transport and cut up the leaf material is comparable to the metabolic energy available from the fungus grown on the leaves, and so conservation of energy is likely to be a particularly strong selective pressure for leafcutter ants. PMID:26909161

  12. Leaf processing behaviour in Atta leafcutter ants: 90% of leaf cutting takes place inside the nest, and ants select pieces that require less cutting

    PubMed Central

    Garrett, Ryan W.; Carlson, Katherine A.; Goggans, Matthew Scott; Nesson, Michael H.; Shepard, Christopher A.; Schofield, Robert M. S.

    2016-01-01

    Leafcutter ants cut trimmings from plants, carry them to their underground nests and cut them into smaller pieces before inoculating them with a fungus that serves as a primary food source for the colony. Cutting is energetically costly, so the amount of cutting is important in understanding foraging energetics. Estimates of the cutting density, metres of cutting per square metre of leaf, were made from samples of transported leaf cuttings and of fungal substrate from field colonies of Atta cephalotes and Atta colombica. To investigate cutting inside the nest, we made leaf-processing observations of our laboratory colony, A. cephalotes. We did not observe the commonly reported reduction of the leaf fragments into a pulp, which would greatly increase the energy cost of processing. Video clips of processing behaviours, including behaviours that have not previously been described, are linked. An estimated 2.9 (±0.3) km of cutting with mandibles was required to reduce a square metre of leaf to fungal substrate. Only about 12% (±1%) of this cutting took place outside of the nest. The cutting density and energy cost is lower for leaf material with higher ratios of perimeter to area, so we tested for, and found that the laboratory ants had a preference for leaves that were pre-cut into smaller pieces. Estimates suggest that the energy required to transport and cut up the leaf material is comparable to the metabolic energy available from the fungus grown on the leaves, and so conservation of energy is likely to be a particularly strong selective pressure for leafcutter ants. PMID:26909161

  13. 49 CFR 7.13 - Records available.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 1 2010-10-01 2010-10-01 false Records available. 7.13 Section 7.13 Transportation Office of the Secretary of Transportation PUBLIC AVAILABILITY OF INFORMATION Availability of... be expected to endanger the life or physical safety of any individual; (8) Contained in or related...

  14. Sensitivity of leaf size and shape to climate: global patterns and paleoclimatic applications.

    PubMed

    Peppe, Daniel J; Royer, Dana L; Cariglino, Bárbara; Oliver, Sofia Y; Newman, Sharon; Leight, Elias; Enikolopov, Grisha; Fernandez-Burgos, Margo; Herrera, Fabiany; Adams, Jonathan M; Correa, Edwin; Currano, Ellen D; Erickson, J Mark; Hinojosa, Luis Felipe; Hoganson, John W; Iglesias, Ari; Jaramillo, Carlos A; Johnson, Kirk R; Jordan, Gregory J; Kraft, Nathan J B; Lovelock, Elizabeth C; Lusk, Christopher H; Niinemets, Ulo; Peñuelas, Josep; Rapson, Gillian; Wing, Scott L; Wright, Ian J

    2011-05-01

    • Paleobotanists have long used models based on leaf size and shape to reconstruct paleoclimate. However, most models incorporate a single variable or use traits that are not physiologically or functionally linked to climate, limiting their predictive power. Further, they often underestimate paleotemperature relative to other proxies. • Here we quantify leaf-climate correlations from 92 globally distributed, climatically diverse sites, and explore potential confounding factors. Multiple linear regression models for mean annual temperature (MAT) and mean annual precipitation (MAP) are developed and applied to nine well-studied fossil floras. • We find that leaves in cold climates typically have larger, more numerous teeth, and are more highly dissected. Leaf habit (deciduous vs evergreen), local water availability, and phylogenetic history all affect these relationships. Leaves in wet climates are larger and have fewer, smaller teeth. Our multivariate MAT and MAP models offer moderate improvements in precision over univariate approaches (± 4.0 vs 4.8°C for MAT) and strong improvements in accuracy. For example, our provisional MAT estimates for most North American fossil floras are considerably warmer and in better agreement with independent paleoclimate evidence. • Our study demonstrates that the inclusion of additional leaf traits that are functionally linked to climate improves paleoclimate reconstructions. This work also illustrates the need for better understanding of the impact of phylogeny and leaf habit on leaf-climate relationships. PMID:21294735

  15. 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

  16. Macroevolution of leaf defenses and secondary metabolites across the genus Helianthus.

    PubMed

    Mason, Chase M; Bowsher, Alan W; Crowell, Breanna L; Celoy, Rhodesia M; Tsai, Chung-Jui; Donovan, Lisa A

    2016-03-01

    Leaf defenses are widely recognized as key adaptations and drivers of plant evolution. Across environmentally diverse habitats, the macroevolution of leaf defenses can be predicted by the univariate trade-off model, which predicts that defenses are functionally redundant and thus trade off, and the resource availability hypothesis, which predicts that defense investment is determined by inherent growth rate and that higher defense will evolve in lower resource environments. Here, we examined the evolution of leaf physical and chemical defenses and secondary metabolites in relation to environmental characteristics and leaf economic strategy across 28 species of Helianthus (the sunflowers). Using a phylogenetic comparative approach, we found few evolutionary trade-offs among defenses and no evidence for defense syndromes. We also found that leaf defenses are strongly related to leaf economic strategy, with higher defense in more resource-conservative species, although there is little support for the evolution of higher defense in low-resource habitats. A wide variety of physical and chemical defenses predict resistance to different insect herbivores, fungal pathogens, and a parasitic plant, suggesting that most sunflower defenses are not redundant in function and that wild Helianthus represents a rich source of variation for the improvement of crop sunflower. PMID:26583880

  17. Sensitivity of leaf size and shape to climate: Global patterns and paleoclimatic applications

    USGS Publications Warehouse

    Peppe, D.J.; Royer, D.L.; Cariglino, B.; Oliver, S.Y.; Newman, S.; Leight, E.; Enikolopov, G.; Fernandez-Burgos, M.; Herrera, F.; Adams, J.M.; Correa, E.; Currano, E.D.; Erickson, J.M.; Hinojosa, L.F.; Hoganson, J.W.; Iglesias, A.; Jaramillo, C.A.; Johnson, K.R.; Jordan, G.J.; Kraft, N.J.B.; Lovelock, E.C.; Lusk, C.H.; Niinemets, U.; Penuelas, J.; Rapson, G.; Wing, S.L.; Wright, I.J.

    2011-01-01

    Paleobotanists have long used models based on leaf size and shape to reconstruct paleoclimate. However, most models incorporate a single variable or use traits that are not physiologically or functionally linked to climate, limiting their predictive power. Further, they often underestimate paleotemperature relative to other proxies. Here we quantify leaf-climate correlations from 92 globally distributed, climatically diverse sites, and explore potential confounding factors. Multiple linear regression models for mean annual temperature (MAT) and mean annual precipitation (MAP) are developed and applied to nine well-studied fossil floras. We find that leaves in cold climates typically have larger, more numerous teeth, and are more highly dissected. Leaf habit (deciduous vs evergreen), local water availability, and phylogenetic history all affect these relationships. Leaves in wet climates are larger and have fewer, smaller teeth. Our multivariate MAT and MAP models offer moderate improvements in precision over univariate approaches (??4.0 vs 4.8??C for MAT) and strong improvements in accuracy. For example, our provisional MAT estimates for most North American fossil floras are considerably warmer and in better agreement with independent paleoclimate evidence. Our study demonstrates that the inclusion of additional leaf traits that are functionally linked to climate improves paleoclimate reconstructions. This work also illustrates the need for better understanding of the impact of phylogeny and leaf habit on leaf-climate relationships. ?? 2011 The Authors. New Phytologist ?? 2011 New Phytologist Trust.

  18. 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

  19. 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

  20. 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

  1. 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...

  2. 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

  3. 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.

  4. 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...

  5. Astatine-211: Production and Availability

    PubMed Central

    Zalutsky, Michael R.; Pruszynski, Marek

    2012-01-01

    The 7.2-h half life radiohalogen 211At offers many potential advantages for targeted α-particle therapy; however, its use for this purpose is constrained by its limited availability. Astatine-211 can be produced in reasonable yield from natural bismuth targets via the 209Bi( α,2n)211At nuclear reaction utilizing straightforward methods. There is some debate as to the best incident α-particle energy for maximizing 211At production while minimizing production of 210At, which is problematic because of its 138.4-day half life α-particle emitting daughter, 210Po. The intrinsic cost for producing 211At is reasonably modest and comparable to that of commercially available 123I. The major impediment to 211At availability is attributed to the need for a medium energy α-particle beam for its production. On the other hand, there are about 30 cyclotrons in the world that have the beam characteristics required for 211At production. PMID:22201707

  6. Astatine-211: production and availability.

    PubMed

    Zalutsky, Michael R; Pruszynski, Marek

    2011-07-01

    The 7.2-h half life radiohalogen (211)At offers many potential advantages for targeted α-particle therapy; however, its use for this purpose is constrained by its limited availability. Astatine-211 can be produced in reasonable yield from natural bismuth targets via the (209)Bi(α,2n)(211)At nuclear reaction utilizing straightforward methods. There is some debate as to the best incident α-particle energy for maximizing 211At production while minimizing production of (210)At, which is problematic because of its 138.4-day half life α-particle emitting daughter, (210)Po. The intrinsic cost for producing (211)At is reasonably modest and comparable to that of commercially available (123)I. The major impediment to (211)At availability is attributed to the need for a medium energy α-particle beam for its production. On the other hand, there are about 30 cyclotrons in the world that have the beam characteristics required for (211)At production. PMID:22201707

  7. Influence of nitrate availability in production of plant carbon-based chemical defenses

    SciTech Connect

    Mihaliak, C.A.

    1987-01-01

    Rosettes of Heterotheca subaxillaris (Asteraceae) allocate greater quantities of carbon to root growth and leaf mono- and sesqui-terpenes as nitrate availability declines. Greater genetic variation and phenotypic plasticity of leaf volatile terpene accumulation occur in a population where nitrate availability is variable, relative to beetles occurring under consistently low nitrate availability conditions. Differences between beetle populations in volatile leaf terpene content appear to be primarily environmental in origin rather than genetic. Time-course /sup 14/CO/sub 2/ tracer studies suggest that the higher leaf volatile terpene content observed under nitrate-limitation may result from increased synthesis of a long-term volatile terpene pool. Accumulation of volatile terpenes under nitrate-limitation may reflect an increased pool of carbon and energy maintained at the sites of volatile terpenoid synthesis.

  8. Availability growth modeling

    SciTech Connect

    Wendelberger, J.R.

    1998-12-01

    In reliability modeling, the term availability is used to represent the fraction of time that a process is operating successfully. Several different definitions have been proposed for different types of availability. One commonly used measure of availability is cumulative availability, which is defined as the ratio of the amount of time that a system is up and running to the total elapsed time. During the startup phase of a process, cumulative availability may be treated as a growth process. A procedure for modeling cumulative availability as a function of time is proposed. Estimates of other measures of availability are derived from the estimated cumulative availability function. The use of empirical Bayes techniques to improve the resulting estimates is also discussed.

  9. 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.

  10. 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

  11. 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

  12. 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

  13. Limited life item management

    NASA Technical Reports Server (NTRS)

    Eaglen, R. L.

    1971-01-01

    Plans are available for age-sensitive hardware management. Control plan identifies shelf life or age control requirements for materials considered age sensitive, use sensitive, or time service or shelf life controlled items, and describes methods of arriving at age controls through adherence to detailed specifications.

  14. Potato leaf explants as a spaceflight plant test system

    NASA Technical Reports Server (NTRS)

    Wheeler, R. M.

    1986-01-01

    The use of explant tissues or organs may circumvent limitations facing whole-plant experimentation during spaceflight. In the case of potato, a crop currently being studied for application to bioregenerative life support systems, excised leaves and their subtended axillary buds can be used to test a variety of stem growth and development phases ranging from tubers through stolons (horizontal stems) to upright leafy shoots. The leaves can be fit well into small-volume test packages and sustained under relatively low irradiance levels using light-weight growing media. Tubers formed on potato leaf cuttings can yield up from 0.5 to 1.0 g fresh mass 10 days after excision and up to 2.0 g or more, 14 days from excision.

  15. Weak coordination among petiole, leaf, vein, and gas-exchange traits across 41 Australian angiosperm species and its possible implications

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Background and Aims Close coordination between leaf gas exchange and maximal hydraulic supply has been reported across diverse plant life-forms. However, recent reports suggest that this relationship may become weak or break down completely within the angiosperms. Methods To examine this possi...

  16. 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

  17. Construction and Maintenance of the Optimal Photosynthetic Systems of the Leaf, Herbaceous Plant and Tree: an Eco-developmental Treatise

    PubMed Central

    TERASHIMA, ICHIRO; ARAYA, TAKAO; MIYAZAWA, SHIN-ICHI; SONE, KOSEI; YANO, SATOSHI

    2004-01-01

    • Background and Aims The paper by Monsi and Saeki in 1953 (Japanese Journal of Botany 14: 22–52) was pioneering not only in mathematical modelling of canopy photosynthesis but also in eco-developmental studies of seasonal changes in leaf canopies. • Scope Construction and maintenance mechanisms of efficient photosynthetic systems at three different scaling levels—single leaves, herbaceous plants and trees—are reviewed mainly based on the nitrogen optimization theory. First, the nitrogen optimization theory with respect to the canopy and the single leaf is briefly introduced. Secondly, significance of leaf thickness in CO2 diffusion in the leaf and in leaf photosynthesis is discussed. Thirdly, mechanisms of adjustment of photosynthetic properties of the leaf within the herbaceous plant individual throughout its life are discussed. In particular, roles of sugar sensing, redox control and of cytokinin are highlighted. Finally, the development of a tree is considered. • Conclusions Various mechanisms contribute to construction and maintenance of efficient photosynthetic systems. Molecular backgrounds of these ecologically important mechanisms should be clarified. The construction mechanisms of the tree cannot be explained solely by the nitrogen optimization theory. It is proposed that the pipe model theory in its differential form could be a potential tool in future studies in this research area. PMID:15598701

  18. 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.

  19. Life's crucible.

    PubMed

    Radetsky, P

    1998-02-01

    Research by German chemists Gunter Wachtershauser and Claudia Huber about the origins of life is reviewed. Other theories about the beginning of life on Earth are examined with comments by noted researchers. PMID:11541839

  20. 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.

  1. 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.

  2. Do pH changes in the leaf apoplast contribute to rapid inhibition of leaf elongation rate by water stress? Comparison of stress responses induced by polyethylene glycol and down-regulation of root hydraulic conductivity.

    PubMed

    Ehlert, Christina; Plassard, Claude; Cookson, Sarah Jane; Tardieu, François; Simonneau, Thierry

    2011-08-01

    We have dissected the influences of apoplastic pH and cell turgor on short-term responses of leaf growth to plant water status, by using a combination of a double-barrelled pH-selective microelectrodes and a cell pressure probe. These techniques were used, together with continuous measurements of leaf elongation rate (LER), in the (hidden) elongating zone of the leaves of intact maize plants while exposing roots to various treatments. Polyethylene glycol (PEG) reduced water availability to roots, while acid load and anoxia decreased root hydraulic conductivity. During the first 30 min, acid load and anoxia induced moderate reductions in leaf growth and turgor, with no effect on leaf apoplastic pH. PEG stopped leaf growth, while turgor was only partially reduced. Rapid alkalinization of the apoplast, from pH 4.9 ± 0.3 to pH 5.8 ± 0.2 within 30 min, may have participated to this rapid growth reduction. After 60 min, leaf growth inhibition correlated well with turgor reduction across all treatments, supporting a growth limitation by hydraulics. We conclude that apoplastic alkalinization may transiently impair the control of leaf growth by cell turgor upon abrupt water stress, whereas direct hydraulic control of growth predominates under moderate conditions and after a 30-60 min delay following imposition of water stress. PMID:21477119

  3. 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

  4. Leaf litter dynamics and litter consumption in two temperate South Australian mangrove forests

    NASA Astrophysics Data System (ADS)

    Imgraben, Sarah; Dittmann, Sabine

    2008-02-01

    The dynamics and consumption of mangrove litter were investigated in two temperate Avicennia marina dominated forests in South Australia in order to compare production and fate of leaf litter with records from tropical and temperate mangroves. Litterfall was measured using traps over four months in the summer of 2004/2005. Average amount of litter was 2.1 and 3.2 g dwt m - 2 d - 1 , respectively, at the two study sites. Leaves accounted for most of the litterfall, followed by propagules and wood. Litterfall varied over time, and depending on the site and inundation time. The standing stock of leaf litter on the forest floor amounted to 15.5 g m - 2 dwt in March 2005. Decomposition determined by litter bags suggested that leaves lost ˜ 50% of their weight in the first two weeks of exposure, with little further weight loss over longer exposure times. Leaf consumption was investigated with a series of laboratory experiments, using the grapsid crab Helograpsus haswellianus, two snail species ( Salinator fragilis and Austrocochlea concamerata) and the polychaete Neanthes vaalii as potential consumers. There was no consumption of new leaves, and the only significant consumption of aged leaves was found for female H. haswellianus. H. haswellianus consumed 0.1 g dwt d - 1 of senescent leaves in the experiment, equivalent to 0.18 g m - 2 d - 1 in the field (average crab density 1.8 ind m - 2 ), or 9.4% of the average daily leaf litterfall. Experiments with propagules revealed no significant consumption by the crabs. High decomposition and low consumption rates of crabs account for the high accumulation and possible export of leaf litter from these mangroves. Leaf litter availability is not a limiting factor for invertebrate consumers in these temperate mangrove forests, and the low consumption rates imply a major difference in the fate of leaf litter between tropical and temperate mangrove systems.

  5. Habitat, food, and climate affecting leaf litter anuran assemblages in an Atlantic Forest remnant

    NASA Astrophysics Data System (ADS)

    Rievers, Camila Rabelo; Pires, Maria Rita Silvério; Eterovick, Paula Cabral

    2014-07-01

    Leaf litter anuran assemblages include both species that have terrestrial development and species that, during the breeding season, aggregate around bodies of water where their tadpoles develop. The resources used by these two groups in the leaf litter are likely to differ, as well as their sampled species richness, abundance and biomass as resource availability changes. We conducted a 12-month survey of leaf litter anuran assemblages at three forest areas in the largest Atlantic Forest remnant in the state of Minas Gerais in southeastern Brazil. Each month we estimated, based on capture rates, anuran species richness, abundance, and biomass as assemblage descriptors. We also measured variables that could potentially affect these descriptors in space and time: invertebrate litter fauna (abundance and richness of taxa), leaf litter biomass, and microclimatic conditions (air humidity, air and soil temperature, soil water content, and rainfall). We tested for differences in these variables among areas. We used general linear models to search for the variables that best explained variation in anuran abundance (based on capture rates) throughout the year. We analyzed species with terrestrial development (TD) and with aquatic larvae (AL) separately. We recorded 326 anurans of 15 species. Sampled anuran abundance (correlated to species richness and biomass) was explained by air humidity and/or invertebrate abundance for species with TD, and by soil water content or air humidity and leaf litter biomass for species with AL. The variability in the results of studies on leaf litter frogs that try to find variables to explain changes in community descriptors may be due to spatial variation of resources among areas and also to the fact that TD and AL species are frequently analyzed together, when in fact they are likely to show different responses to resources present in the leaf litter habitat, reflected on capture rates.

  6. 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...

  7. High Availability Electronics Standards

    SciTech Connect

    Larsen, R.S.; /SLAC

    2006-12-13

    Availability modeling of the proposed International Linear Collider (ILC) predicts unacceptably low uptime with current electronics systems designs. High Availability (HA) analysis is being used as a guideline for all major machine systems including sources, utilities, cryogenics, magnets, power supplies, instrumentation and controls. R&D teams are seeking to achieve total machine high availability with nominal impact on system cost. The focus of this paper is the investigation of commercial standard HA architectures and packaging for Accelerator Controls and Instrumentation. Application of HA design principles to power systems and detector instrumentation are also discussed.

  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. 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

  5. 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

  6. 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

  7. 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).

  8. 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,...

  9. 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...

  10. 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...

  11. 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,...

  12. 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,...

  13. 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.

  14. 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...

  15. 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...

  16. Leafing out phenology in woody plants of the Northern Hempisphere show phylogenetic, ecological and anatomical patterns

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Leafing out phenology affects a wide variety of ecosystem processes and ecological interactions, and it affects how natural and artificial ecosystems respond to different weather conditions in the spring. There is, however, relatively little information available on the factors affecting species dif...

  17. Canopy cover and leaf area index relationships for wheat, triticale, and corn

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The AquaCrop model requires canopy cover (CC) measurements to define crop growth and development. Some previously collected data sets that would be useful for calibrating and validating AquaCrop contain only leaf area index (LAI) data, but could be used if relationships were available relating LAI t...

  18. Draft Genome Sequence of Cercospora arachidicola, Causal Agent of Early Leaf Spot in Peanuts

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cercospora arachidicola, an economically important pathogen of peanut, is the cause of early leaf spot disease. Despite its significance, insufficient genetic information is available for utilization. Understanding the genetic diversity of this pathogen is crucial for peanut breeding programs to d...

  19. Sensitivity of leaf size and shape to climate within Acer rubrum and Quercus kelloggii.

    PubMed

    Royer, Dana L; McElwain, Jennifer C; Adams, Jonathan M; Wilf, Peter

    2008-01-01

    * Variation in the size and shape (physiognomy) of leaves has long been correlated to climate, and paleobotanists have used these correlations to reconstruct paleo-climate. Most studies focus on site-level means of largely nonoverlapping species sets. The sensitivity of leaf shape to climate within species is poorly known, which limits our general understanding of leaf-climate relationships and the value of intraspecific patterns for paleoclimate reconstructions. * The leaf physiognomy of two species whose native North American ranges span large climatic gradients (Acer rubrum and Quercus kelloggii) was quantified and correlated to mean annual temperature (MAT). Quercus kelloggii was sampled across a wide elevation range, but A. rubrum was sampled in strictly lowland areas. * Within A. rubrum, leaf shape correlates with MAT in a manner that is largely consistent with previous site-level studies; leaves from cold climates are toothier and more highly dissected. By contrast, Q. kelloggii is largely insensitive to MAT; instead, windy conditions with ample plant-available water may explain the preponderance of small teeth at high elevation sites, independent of MAT. * This study highlights the strong correspondence between leaf form and climate within some species, and demonstrates that intraspecific patterns may contribute useful information towards reconstructing paleoclimate. PMID:18507771

  20. Elongation growth of the leaf sheath base of Avena sativa seedlings: regulation by hormones and sucrose

    NASA Technical Reports Server (NTRS)

    Brock, T. G.; Kaufman, P. B.

    1991-01-01

    The leaf sheath base of the seedling of Avena sativa was characterized for growth response to hormones and sucrose. Six day old plants, raised under a 10:14 hr light:dark cycle, were excised at the coleoptilar node and 1 cm above the node for treatment. The growth of the leaf sheath base was promoted by gibberellic acid (GA3) and this response was dose dependent. The lag to response initiation was approximately 4 hr. Growth with or without GA3 (10 micromoles) was transient, diminishing appreciably after 48 hr. The addition of 10 mM sucrose greatly prolonged growth; the effect of GA3 and sucrose was additive. Neither indole-3-acetic acid (IAA) nor the cytokinin N6-benzyladenine (BA), alone or in combination, promoted the growth of leaf sheath bases. However, both significantly inhibited the action of GA3. The inhibitory effect of IAA was dose dependent and was not affected by the addition of BA or sucrose. These results indicate that the growth of leaf sheath bases of Avena sativa is promoted specifically by gibberellin, that this action depends on the availability of carbohydrates from outside of the leaf sheath base, and that the promotional effect of GA3 can be modified by either auxins or cytokinins.

  1. Plantecophys - An R Package for Analysing and Modelling Leaf Gas Exchange Data

    PubMed Central

    Duursma, Remko A.

    2015-01-01

    Here I present the R package 'plantecophys', a toolkit to analyse and model leaf gas exchange data. Measurements of leaf photosynthesis and transpiration are routinely collected with portable gas exchange instruments, and analysed with a few key models. These models include the Farquhar-von Caemmerer-Berry (FvCB) model of leaf photosynthesis, the Ball-Berry models of stomatal conductance, and the coupled leaf gas exchange model which combines the supply and demand functions for CO2 in the leaf. The 'plantecophys' R package includes functions for fitting these models to measurements, as well as simulating from the fitted models to aid in interpreting experimental data. Here I describe the functionality and implementation of the new package, and give some examples of its use. I briefly describe functions for fitting the FvCB model of photosynthesis to measurements of photosynthesis-CO2 response curves ('A-Ci curves'), fitting Ball-Berry type models, modelling C3 photosynthesis with the coupled photosynthesis-stomatal conductance model, modelling C4 photosynthesis, numerical solution of optimal stomatal behaviour, and energy balance calculations using the Penman-Monteith equation. This open-source package makes technically challenging calculations easily accessible for many users and is freely available on CRAN. PMID:26581080

  2. Plantecophys--An R Package for Analysing and Modelling Leaf Gas Exchange Data.

    PubMed

    Duursma, Remko A

    2015-01-01

    Here I present the R package 'plantecophys', a toolkit to analyse and model leaf gas exchange data. Measurements of leaf photosynthesis and transpiration are routinely collected with portable gas exchange instruments, and analysed with a few key models. These models include the Farquhar-von Caemmerer-Berry (FvCB) model of leaf photosynthesis, the Ball-Berry models of stomatal conductance, and the coupled leaf gas exchange model which combines the supply and demand functions for CO2 in the leaf. The 'plantecophys' R package includes functions for fitting these models to measurements, as well as simulating from the fitted models to aid in interpreting experimental data. Here I describe the functionality and implementation of the new package, and give some examples of its use. I briefly describe functions for fitting the FvCB model of photosynthesis to measurements of photosynthesis-CO2 response curves ('A-Ci curves'), fitting Ball-Berry type models, modelling C3 photosynthesis with the coupled photosynthesis-stomatal conductance model, modelling C4 photosynthesis, numerical solution of optimal stomatal behaviour, and energy balance calculations using the Penman-Monteith equation. This open-source package makes technically challenging calculations easily accessible for many users and is freely available on CRAN. PMID:26581080

  3. 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

  4. Prospect inversion for indirect estimation of leaf dry matter content and specific leaf area

    NASA Astrophysics Data System (ADS)

    Ali, A.; Darvishzadeh, R.; Skidmore, A.-K.; Duren, I.-V.; Heiden, U.; Heurich, M.

    2015-04-01

    Quantification of vegetation properties plays an indispensable role in assessments of ecosystem function with leaf dry mater content (LDMC) and specific leaf area (SLA) being two important vegetation properties. Methods for fast, reliable and accurate measurement of LDMC and SLA are still lacking. In this study, the inversion of the PROSPECT radiative transfer model was used to estimate these two leaf parameters. Inversion of PROSPECT traditionally aims at quantifying its direct input parameters rather than identifying the parameters which can be derived indirectly from the input parameters. The technique has been tested here to indirectly model these parameters for the first time. Biophysical parameters such as leaf area, as well as fresh and dry weights of 137 leaf samples were measured during a field campaign in July 2013 in the mixed mountain forests of the Bavarian Forest National Park, Germany. Reflectance and transmittance of the leaf samples were measured using an ASD field spec III equipped with an integrating sphere. The PROSPECT model was inverted using a look-up table (LUT) approach for the NIR/SWIR region of the spectrum. The retrieved parameters were evaluated using their calculated R2 and normalized root mean square error (nRMSE) values with the field measurements. Among the retrieved variables the lowest nRMSE (0.0899) was observed for LDMC. For both traits higher R2 values (0.83 for LDMC and 0.89 for SLA) were discovered. The results indicate that the leaf traits studied can be quantified as accurately as the direct input parameters of PROSPECT. The strong correlation between the estimated traits and the NIR/SWIR region of the electromagnetic spectrum suggests that these leaf traits could be assessed at canopy and in the landscape by using hyperspectral remote sensing data.

  5. Local available quantum correlations

    NASA Astrophysics Data System (ADS)

    Mundarain, Douglas F.; de Guevara, María L. Ladrón

    2015-12-01

    In this work, local available quantum correlations are studied. They are defined in terms of mutual information of bipartite local measurements done over an optimal local basis complementary to the local basis which defines the respective classical correlations. For two qubits, it is always possible to choose the basis of classical correlations as the set of eigenvectors of σ _z (the third Pauli matrix) and complementary bases become the sets of eigenvectors of the observables orthogonal to σ _z. It is shown that all states with zero local available quantum correlations are separable but not necessarily strictly classical; this fact puts this kind of correlations in the middle between discord and entanglement. Since in many cases it may suffice to know whether a given state has quantum correlations, the structure of the states with zero local available quantum correlations is presented. It is also shown that there is a close connection between local available quantum correlations and the protocol of entanglement activation developed by Piani et al. (Phys Rev Lett 106:220403, 2011). If a state satisfies the sufficient condition for the entanglement swapping associated with this protocol, this state has nonzero local available quantum correlations.

  6. Chloroplasts Are Central Players in Sugar-Induced Leaf Growth.

    PubMed

    Van Dingenen, Judith; De Milde, Liesbeth; Vermeersch, Mattias; Maleux, Katrien; De Rycke, Riet; De Bruyne, Michiel; Storme, Véronique; Gonzalez, Nathalie; Dhondt, Stijn; Inzé, Dirk

    2016-05-01

    Leaves are the plant's powerhouses, providing energy for all organs through sugar production during photosynthesis. However, sugars serve not only as a metabolic energy source for sink tissues but also as signaling molecules, affecting gene expression through conserved signaling pathways to regulate plant growth and development. Here, we describe an in vitro experimental assay, allowing one to alter the sucrose (Suc) availability during early Arabidopsis (Arabidopsis thaliana) leaf development, with the aim to identify the affected cellular and molecular processes. The transfer of seedlings to Suc-containing medium showed a profound effect on leaf growth by stimulating cell proliferation and postponing the transition to cell expansion. Furthermore, rapidly after transfer to Suc, mesophyll cells contained fewer and smaller plastids, which are irregular in shape and contain fewer starch granules compared with control mesophyll cells. Short-term transcriptional responses after transfer to Suc revealed the repression of well-known sugar-responsive genes and multiple genes encoded by the plastid, on the one hand, and up-regulation of a GLUCOSE-6-PHOSPHATE TRANSPORTER (GPT2), on the other hand. Mutant gpt2 seedlings showed no stimulation of cell proliferation and no repression of chloroplast-encoded transcripts when transferred to Suc, suggesting that GPT2 plays a critical role in the Suc-mediated effects on early leaf growth. Our findings, therefore, suggest that induction of GPT2 expression by Suc increases the import of glucose-6-phosphate into the plastids that would repress chloroplast-encoded transcripts, restricting chloroplast differentiation. Retrograde signaling from the plastids would then delay the transition to cell expansion and stimulate cell proliferation. PMID:26932234

  7. Stimulated Leaf Dark Respiration in Tomato in an Elevated Carbon Dioxide Atmosphere

    PubMed Central

    Li, Xin; Zhang, Guanqun; Sun, Bo; Zhang, Shuai; Zhang, Yiqing; Liao, Yangwenke; Zhou, Yanhong; Xia, Xiaojian; Shi, Kai; Yu, Jingquan

    2013-01-01

    It is widely accepted that leaf dark respiration is a determining factor for the growth and maintenance of plant tissues and the carbon cycle. However, the underlying effect and mechanism of elevated CO2 concentrations ([CO2]) on dark respiration remain unclear. In this study, tomato plants grown at elevated [CO2] showed consistently higher leaf dark respiratory rate, as compared with ambient control plants. The increased respiratory capacity was driven by a greater abundance of proteins, carbohydrates, and transcripts involved in pathways of glycolysis carbohydrate metabolism, the tricarboxylic acid cycle, and mitochondrial electron transport energy metabolism. This study provides substantial evidence in support of the concept that leaf dark respiration is increased by elevated [CO2] in tomato plants and suggests that the increased availability of carbohydrates and the increased energy status are involved in the increased rate of dark respiration in response to elevated [CO2]. PMID:24305603

  8. Effects of precipitation regime and soil nitrogen on leaf traits in seasonally dry tropical forests of the Yucatan Peninsula, Mexico.

    PubMed

    Roa-Fuentes, Lilia L; Templer, Pamela H; Campo, Julio

    2015-10-01

    Leaf traits are closely associated with nutrient use by plants and can be utilized as a proxy for nutrient cycling processes. However, open questions remain, in particular regarding the variability of leaf traits within and across seasonally dry tropical forests. To address this, we considered six leaf traits (specific area, thickness, dry matter content, N content, P content and natural abundance (15)N) of four co-occurring tree species (two that are not associated with N2-fixing bacteria and two that are associated with N2-fixing bacteria) and net N mineralization rates and inorganic N concentrations along a precipitation gradient (537-1036 mm per year) in the Yucatan Peninsula, Mexico. Specifically we sought to test the hypothesis that leaf traits of dominant plant species shift along a precipitation gradient, but are affected by soil N cycling. Although variation among different species within each site explains some leaf trait variation, there is also a high level of variability across sites, suggesting that factors other than precipitation regime more strongly influence leaf traits. Principal component analyses indicated that across sites and tree species, covariation in leaf traits is an indicator of soil N availability. Patterns of natural abundance (15)N in foliage and foliage minus soil suggest that variation in precipitation regime drives a shift in plant N acquisition and the openness of the N cycle. Overall, our study shows that both plant species and site are important determinants of leaf traits, and that the leaf trait spectrum is correlated with soil N cycling. PMID:26013874

  9. Effects of grazing on leaf traits and ecosystem functioning in Inner Mongolia grasslands: scaling from species to community

    NASA Astrophysics Data System (ADS)

    Zheng, S. X.; Ren, H. Y.; Lan, Z. C.; Li, W. H.; Bai, Y. F.

    2009-10-01

    More attention has focused on using some easily measured plant functional traits to predict grazing influence on plant growth and ecosystem functioning. However, there has been much controversy on leaf traits response to grazing, thus more research should be conducted at the species level. Here we investigated the leaf area, leaf mass and specific leaf area (SLA) of 263 species in eight grassland communities along a soil moisture gradient in the Xilin River Basin, a semiarid grassland of northern China, to explore the grazing effects on ecosystem functioning. Results demonstrated that grazing decreased the leaf area and leaf mass in more than 56% of species in the Xilin River Basin, however, responses of SLA to grazing varied widely between species. Grazing increased SLA in 38.4% of species, decreased SLA in 31.3% of species and had no effect on 30.3% of species. Annuals and biennials generally developed high SLA as grazing tolerance traits, while perennial graminoids developed low SLA as grazing avoidance traits. Considering the water ecotypes, the SLA-increased and SLA-unchanged species were dominated by hygrophytes and mesophytes, while the SLA-decreased species were dominated by xerophytes. At the community level, grazing decreased the mean leaf area index (LAI) of six communities by 16.9%, leaf biomass by 35.2% and standing aboveground biomass (SAB) by 35.0% in the Xilin River Basin, indicating that overgrazing greatly decreased the ecosystem functioning in the semi-arid grassland of northern China. Soil properties, especially fielding holding capacity and soil organic carbon and total nitrogen could mediate the negative grazing impacts. The results suggest SLA is a better leaf trait to reveal plant adaptability to grazing. Our findings have practical implications for range management and productivity maintenance in the semiarid grassland, and it is feasible to take some measures such as ameliorating soil water and nutrient availabilities to prevent grassland

  10. Condom availability for adolescents.

    PubMed

    1996-06-01

    Although abstinence should be stressed as the certain way to prevent STDs and pregnancy, sexually active teens, male and female, must nonetheless be taught to use condoms properly, effectively, and consistently. The latex condom should be made widely available to young people. Ideally, young persons should have access to education and counseling when contraception is dispensed. However, condoms should be made easily available without any requirement for education. Condoms should be available not only through families, medical facilities, and commercial channels, but also through other appropriate and informed persons, without cost if possible, at sites where adolescents congregate. These sites may include schools, clubs, and other youth-serving agencies. A clear message from the medical community supporting condom use will enhance compliance. PMID:8803728

  11. An evolutionary perspective on leaf economics: phylogenetics of leaf mass per area in vascular plants.

    PubMed

    Flores, Olivier; Garnier, Eric; Wright, Ian J; Reich, Peter B; Pierce, Simon; Dìaz, Sandra; Pakeman, Robin J; Rusch, Graciela M; Bernard-Verdier, Maud; Testi, Baptiste; Bakker, Jan P; Bekker, Renée M; Cerabolini, Bruno E L; Ceriani, Roberta M; Cornu, Guillaume; Cruz, Pablo; Delcamp, Matthieu; Dolezal, Jiri; Eriksson, Ove; Fayolle, Adeline; Freitas, Helena; Golodets, Carly; Gourlet-Fleury, Sylvie; Hodgson, John G; Brusa, Guido; Kleyer, Michael; Kunzmann, Dieter; Lavorel, Sandra; Papanastasis, Vasilios P; Pérez-Harguindeguy, Natalia; Vendramini, Fernanda; Weiher, Evan

    2014-07-01

    In plant leaves, resource use follows a trade-off between rapid resource capture and conservative storage. This "worldwide leaf economics spectrum" consists of a suite of intercorrelated leaf traits, among which leaf mass per area, LMA, is one of the most fundamental as it indicates the cost of leaf construction and light-interception borne by plants. We conducted a broad-scale analysis of the evolutionary history of LMA across a large dataset of 5401 vascular plant species. The phylogenetic signal in LMA displayed low but significant conservatism, that is, leaf economics tended to be more similar among close relatives than expected by chance alone. Models of trait evolution indicated that LMA evolved under weak stabilizing selection. Moreover, results suggest that different optimal phenotypes evolved among large clades within which extremes tended to be selected against. Conservatism in LMA was strongly related to growth form, as were selection intensity and phenotypic evolutionary rates: woody plants showed higher conservatism in relation to stronger stabilizing selection and lower evolutionary rates compared to herbaceous taxa. The evolutionary history of LMA thus paints different evolutionary trajectories of vascular plant species across clades, revealing the coordination of leaf trait evolution with growth forms in response to varying selection regimes. PMID:25165520

  12. An evolutionary perspective on leaf economics: phylogenetics of leaf mass per area in vascular plants

    PubMed Central

    Flores, Olivier; Garnier, Eric; Wright, Ian J; Reich, Peter B; Pierce, Simon; Dìaz, Sandra; Pakeman, Robin J; Rusch, Graciela M; Bernard-Verdier, Maud; Testi, Baptiste; Bakker, Jan P; Bekker, Renée M; Cerabolini, Bruno E L; Ceriani, Roberta M; Cornu, Guillaume; Cruz, Pablo; Delcamp, Matthieu; Dolezal, Jiri; Eriksson, Ove; Fayolle, Adeline; Freitas, Helena; Golodets, Carly; Gourlet-Fleury, Sylvie; Hodgson, John G; Brusa, Guido; Kleyer, Michael; Kunzmann, Dieter; Lavorel, Sandra; Papanastasis, Vasilios P; Pérez-Harguindeguy, Natalia; Vendramini, Fernanda; Weiher, Evan

    2014-01-01

    In plant leaves, resource use follows a trade-off between rapid resource capture and conservative storage. This “worldwide leaf economics spectrum” consists of a suite of intercorrelated leaf traits, among which leaf mass per area, LMA, is one of the most fundamental as it indicates the cost of leaf construction and light-interception borne by plants. We conducted a broad-scale analysis of the evolutionary history of LMA across a large dataset of 5401 vascular plant species. The phylogenetic signal in LMA displayed low but significant conservatism, that is, leaf economics tended to be more similar among close relatives than expected by chance alone. Models of trait evolution indicated that LMA evolved under weak stabilizing selection. Moreover, results suggest that different optimal phenotypes evolved among large clades within which extremes tended to be selected against. Conservatism in LMA was strongly related to growth form, as were selection intensity and phenotypic evolutionary rates: woody plants showed higher conservatism in relation to stronger stabilizing selection and lower evolutionary rates compared to herbaceous taxa. The evolutionary history of LMA thus paints different evolutionary trajectories of vascular plant species across clades, revealing the coordination of leaf trait evolution with growth forms in response to varying selection regimes. PMID:25165520

  13. Genome-wide association study of rice (Oryza sativa L.) leaf traits with a high-throughput leaf scorer

    PubMed Central

    Yang, Wanneng; Guo, Zilong; Huang, Chenglong; Wang, Ke; Jiang, Ni; Feng, Hui; Chen, Guoxing; Liu, Qian; Xiong, Lizhong

    2015-01-01

    Leaves are the plant’s solar panel and food factory, and leaf traits are always key issues to investigate in plant research. Traditional methods for leaf trait measurement are time-consuming. In this work, an engineering prototype has been established for high-throughput leaf scoring (HLS) of a large number of Oryza sativa accessions. The mean absolute per cent of errors in traditional measurements versus HLS were below 5% for leaf number, area, shape, and colour. Moreover, HLS can measure up to 30 leaves per minute. To demonstrate the usefulness of HLS in dissecting the genetic bases of leaf traits, a genome-wide association study (GWAS) was performed for 29 leaf traits related to leaf size, shape, and colour at three growth stages using HLS on a panel of 533 rice accessions. Nine associated loci contained known leaf-related genes, such as Nal1 for controlling the leaf width. In addition, a total of 73, 123, and 177 new loci were detected for traits associated with leaf size, colour, and shape, respectively. In summary, after evaluating the performance with a large number of rice accessions, the combination of GWAS and high-throughput leaf phenotyping (HLS) has proven a valuable strategy to identify the genetic loci controlling rice leaf traits. PMID:25796084

  14. Joint Leaf chlorophyll and leaf area index retrieval from Landsat data using a regularized model inversion system

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Leaf area index (LAI) and leaf chlorophyll (Chl) content represent key biophysical and biochemical controls on water, energy and carbon exchange processes in the terrestrial biosphere. In combination, LAI and leaf Chl content provide critical information on vegetation density, vitality and photosynt...

  15. Genome-wide association study of rice (Oryza sativa L.) leaf traits with a high-throughput leaf scorer.

    PubMed

    Yang, Wanneng; Guo, Zilong; Huang, Chenglong; Wang, Ke; Jiang, Ni; Feng, Hui; Chen, Guoxing; Liu, Qian; Xiong, Lizhong

    2015-09-01

    Leaves are the plant's solar panel and food factory, and leaf traits are always key issues to investigate in plant research. Traditional methods for leaf trait measurement are time-consuming. In this work, an engineering prototype has been established for high-throughput leaf scoring (HLS) of a large number of Oryza sativa accessions. The mean absolute per cent of errors in traditional measurements versus HLS were below 5% for leaf number, area, shape, and colour. Moreover, HLS can measure up to 30 leaves per minute. To demonstrate the usefulness of HLS in dissecting the genetic bases of leaf traits, a genome-wide association study (GWAS) was performed for 29 leaf traits related to leaf size, shape, and colour at three growth stages using HLS on a panel of 533 rice accessions. Nine associated loci contained known leaf-related genes, such as Nal1 for controlling the leaf width. In addition, a total of 73, 123, and 177 new loci were detected for traits associated with leaf size, colour, and shape, respectively. In summary, after evaluating the performance with a large number of rice accessions, the combination of GWAS and high-throughput leaf phenotyping (HLS) has proven a valuable strategy to identify the genetic loci controlling rice leaf traits. PMID:25796084

  16. Detecting Sugarcane yellow leaf virus infection in asymptomatic leaves with hyperspectral remote sensing and associated leaf pigment changes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sugarcane yellow leaf caused by Sugarcane yellow leaf virus (ScYLV) does not produce visual symptoms in most susceptible plants until late in the growing season. An experiment was conducted to determine if leaf reflectance and pigment analysis could be used to determine ScYLV infection prior to sym...

  17. Baby leaf lettuce germplasm enhancement: developing diverse populations with resistance to bacterial leaf spot caused by Xanthomonas campestris pv. vitians

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Baby leaf lettuce cultivars with resistance to bacterial leaf spot (BLS) caused by Xanthomonas campestris pv. vitians (Xcv) are needed to reduce crop losses. The objectives of this research were to assess the genetic diversity for BLS resistance in baby leaf lettuce cultivars and to select early gen...

  18. Leaf movement, photosynthesis and resource use efficiency responses to multiple environmental stress in Glycine max (soybean)

    SciTech Connect

    Rosa, L.M.G.

    1993-01-01

    Increases in the concentration of greenhouse gases in the atmosphere, may cause a significant increase in temperature, with implications for general wind patterns and precipitation. Reductions in stratospheric ozone will result in increased levels of UV-B reaching earth's surface. During their lifetime plants must deal with a variety of co-occurring environmental stresses. Accordingly, studies into plant responses to multiple environmental factors is important to our understanding of limits to their growth, productivity, and distribution. Heliotropic leaf movements are a generalized plant response to environmental stresses, and the pattern of these movements can be altered by resource availability (e.g., water, and nitrogen). Previous greenhouse and field studies have demonstrated damaging effects of UV-B radiation in crop species, including soybean. Documented in this paper are Leaf movement and gas exchange responses of four soybean cultivars with different sensitivity to UV-B radiation to enhanced levels of UV-B, and modifications of these responses caused by water stress and nitrogen fertilization. UV-B radiation had no effect on the patterns of leaf orientation in soybean; however, a ranking of the cultivars based on midday leaf angles was the same as the ranking of these cultivars based on their sensitivity to UV-B radiation. Water and nitrogen altered the leaf movement patterns of soybeans. Gas exchange parameters in all four cultivars responded in a similar fashion to changes in leaf water potential. Reductions in water availability resulted in lower discrimination. Nitrogen fertilization in cv Forrest, also resulted in lower discrimination, especially under low water regimes, indicating a higher water use efficiency for fertilized plants. UV-B radiation resulted in lower discrimination in the UV-B sensitive CNS cultivar, indicating a stronger stomatal limitation to photosynthesis under increased UV-B levels.

  19. High Availability in Optical Networks

    NASA Astrophysics Data System (ADS)

    Grover, Wayne D.; Wosinska, Lena; Fumagalli, Andrea

    2005-09-01

    concepts for survivability, or papers on availability analysis methods or results. Customer, vendor, and researcher viewpoints and priorities will all be given consideration. Especially valuable to the community would be papers that include or provide measured data on actual reliability and availability performance of optical networking components or systems. The scope of the papers includes, but is not limited to, the following topics: Reliability and availability measurement techniques specific to optical network devices or services. Data on SRLG statistics and frequency of different actual failure causes. Real-life accounts or data on failure and repair rates or projected values for use in availability analysis. Availability analysis methods, especially for survivable networks with reconfigurable or adaptive failure-specific responses. Availability analysis and comparisons of basic schemes for survivability. Differentiated availability schemes. Design for Multiple Quality of Protection. Different schemes for on-demand survivable service provisioning. Basic comparisons or proposals of new survivability mechanisms and architectures. Concepts yielding higher than 1+1 protection switching availability at less than 100% redundancy. Survivable service provisioning in domains of optical transparency: dealing with signal impairments. To submit to this special issue, follow the normal procedure for submission to JON, indicating "Feature Issue: Optical Network Availability" in the "Comments" field of the online submission form. For all other questions relating to this feature issue, please send an e-mail to jon@osa.org, subject line "Feature Issue: Optical Network Availability." Additional information can be found on the JON website: http://www.osa-jon.org/submission/

  20. 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

    The hydrogen isotopic composition of plant waxes in sediments is now routinely used as a hydroclimate proxy. This application is based largely on empirical calibrations that have demonstrated continental-scale correlations between source water and lipid hydrogen isotope values. But at smaller spatial scales and for individual locations it is increasingly recognized that factors that modify apparent fractionation between source water and leaf lipid hydrogen isotope values must also be considered. Isotopic enrichment of leaf water during transpiration is key among these secondary factors, and is itself sensitive to changes in hydroclimate. Leaf water enrichment also occurs prior to photosynthetic water uptake, and is therefore independent from cellular-level biomarker synthesis. Recent advances in theory have permitted mechanistic models to be developed that can be used to predict the mean leaf water hydrogen and oxygen isotope composition from readily available meteorological variables. This permits global-scale isoscape maps of leaf water isotopic composition and enrichment above source water to be generated, but these models have not been widely validated at continental spatial scales. We have established a network of twenty-one sites across Europe where we are sampling for leaf-, xylem-, and soil-water isotopes (H and O) at approximately 5-week intervals over the summer growing season. We augment the sample set with weekly to monthly precipitation samples and early- and late-season plant wax lipid samples. Collaborators at each site are conducting the sampling, and most sites are members of the FLUXNET tower network that also record high-resolution meteorological data. We present information on the implementation of the network and preliminary results from the 2014 summer season. The complete dataset will be used to track the evolution of water isotopes from source to leaf water and from leaf water to lipid hydrogen across diverse environments. This will provide

  1. Diel leaf growth cycles in Clusia spp. are related to changes between C3 photosynthesis and crassulacean acid metabolism during development and during water stress.

    PubMed

    Walter, Achim; Christ, Maja M; Rascher, Uwe; Schurr, Ulrich; Osmond, Barry

    2008-04-01

    This study reports evidence that the timing of leaf growth responds to developmental and environmental constraints in Clusia spp. We monitored diel patterns of leaf growth in the facultative C(3)-crassulacean acid metabolism (CAM) species Clusia minor and in the supposedly obligate CAM species Clusia alata using imaging methods and followed diel patterns of CO2 exchange and acidification. Developing leaves of well-watered C. minor showed a C3-like diel pattern of gas exchange and growth, with maximum relative growth rate (RGR) in the early night period. Growth slowed when water was withheld, accompanied by nocturnal CO2 exchange and the diel acid change characteristic of CAM. Maximum leaf RGR shifted from early night to early in the day when water was withheld. In well-watered C. alata, similar changes in the diel pattern of leaf growth occurred with the development of CAM during leaf ontogeny. We hypothesize that the shift in leaf growth cycle that accompanies the switch from C3 photosynthesis to CAM is mainly caused by the primary demand of CAM for substrates for nocturnal CO2 fixation and acid synthesis, thus reducing the availability of carbohydrates for leaf growth at night. Although the shift to leaf growth early in the light is presumably associated with the availability of carbohydrates, source-sink relationships and sustained diurnal acid levels in young leaves of Clusia spp. need further evaluation in relation to growth processes. PMID:18182020

  2. Molecular markers for leaf rust resistance genes in wheat.

    PubMed

    Chełkowski, J; Stepień, L

    2001-01-01

    Over 100 genes of resistance to rust fungi: Puccinia recondita f. sp. tritici, (47 Lr - leaf rust genes), P. striiformis (18 Yr - yellow rust genes) and P. graminis f. sp. tritici (41 Sr - stripe rust genes) have been identified in wheat (Triticum aestivum L.) and its wild relatives according to recent papers. Sixteen Lr resistance genes have been mapped using restriction fragments length polymorphism (RFLP) markers on wheat chromosomes. More than ten Lr genes can be identified in breeding materials by sequence tagged site (STS) specific markers. Gene Lrk 10, closely linked to gene Lr 10, has been cloned and its function recognized. Available markers are presented in this review. The STS, cleaved amplified polymorphic sequence (CAPS) and sequence characterized amplified regions (SCAR) markers found in the literature should be verified using Triticum spp. with different genetic background. Simple sequence repeats (SSR) markers for Lr resistance genes are now also available. PMID:14564046

  3. AGU Legislative Guide available

    NASA Astrophysics Data System (ADS)

    Richman, Barbara T.

    A guide to help AGU members communicate with legislators and government agency officials is available free of charge from AGU headquarters. The guide is based on the premise that input from the scientific community assists government to make decisions based on the latest factual information available.AGU's Guide to Legislative Information and Contacts was developed by AGU's Committee on Public Affairs and is based largely on a publication of the American Institute of Biological Sciences. The guide briefly outlines the key steps in the legislative process and lists sources of information on legislation. The booklet also provides guidelines for corresponding with legislators a n d for providing scientific testimony to Congress. It also delineates some o f the constraints under which AGU must operate when undertaking legislative activities.

  4. Marine gravity image available

    NASA Astrophysics Data System (ADS)

    The image below shows the gravity field from 30-72°S computed from Geosat geodetic mission (GM) and exact repeat mission (ERM) data. A color shaded-relief image of these gravity anomalies is available from NOAA in poster form (report MGG-8, [Marks et al., 1993] and also as a digital gridded data set on CD-ROM. To order, contact the National Geophysical Data Center, E/GC3, 325 Broadway, Boulder, CO 80303.

  5. Clinically Available Pharmacogenomics Tests

    PubMed Central

    Flockhart, DA; Skaar, T; Berlin, DS; Klein, TE; Nguyen, AT

    2009-01-01

    The development of robust and clinically valuable pharmacogenomic tests has been anticipated to be one of the first tangible results of the Human Genome Project. Despite both obvious and unanticipated obstacles, a number of tests have now become available in various practice settings. Lessons can be learned from examination of these tests, the evidence that has catalyzed their use, their value to prescribers, and their merit as tools for personalizing therapeutics. PMID:19369936

  6. The energetic and carbon economic origins of leaf thermoregulation.

    PubMed

    Michaletz, Sean T; Weiser, Michael D; McDowell, Nate G; Zhou, Jizhong; Kaspari, Michael; Helliker, Brent R; Enquist, Brian J

    2016-01-01

    Leaf thermoregulation has been documented in a handful of studies, but the generality and origins of this pattern are unclear. We suggest that leaf thermoregulation is widespread in both space and time, and originates from the optimization of leaf traits to maximize leaf carbon gain across and within variable environments. Here we use global data for leaf temperatures, traits and photosynthesis to evaluate predictions from a novel theory of thermoregulation that synthesizes energy budget and carbon economics theories. Our results reveal that variation in leaf temperatures and physiological performance are tightly linked to leaf traits and carbon economics. The theory, parameterized with global averaged leaf traits and microclimate, predicts a moderate level of leaf thermoregulation across a broad air temperature gradient. These predictions are supported by independent data for diverse taxa spanning a global air temperature range of ∼60 °C. Moreover, our theory predicts that net carbon assimilation can be maximized by means of a trade-off between leaf thermal stability and photosynthetic stability. This prediction is supported by globally distributed data for leaf thermal and photosynthetic traits. Our results demonstrate that the temperatures of plant tissues, and not just air, are vital to developing more accurate Earth system models. PMID:27548589

  7. 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.

  8. 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.

  9. Use of NAP gene to manipulate leaf senescence in plants

    DOEpatents

    Gan, Susheng; Guo, Yongfeng

    2013-04-16

    The present invention discloses transgenic plants having an altered level of NAP protein compared to that of a non-transgenic plant, where the transgenic plants display an altered leaf senescence phenotype relative to a non-transgenic plant, as well as mutant plants comprising an inactivated NAP gene, where mutant plants display a delayed leaf senescence phenotype compared to that of a non-mutant plant. The present invention also discloses methods for delaying leaf senescence in a plant, as well as methods of making a mutant plant having a decreased level of NAP protein compared to that of a non-mutant plant, where the mutant plant displays a delayed leaf senescence phenotype relative to a non-mutant plant. Methods for causing precocious leaf senescence or promoting leaf senescence in a plant are also disclosed. Also disclosed are methods of identifying a candidate plant suitable for breeding that displays a delayed leaf senescence and/or enhanced yield phenotype.

  10. Assimilate transport in phloem sets conditions for leaf gas exchange.

    PubMed

    Nikinmaa, Eero; Hölttä, Teemu; Hari, Pertti; Kolari, Pasi; Mäkelä, Annikki; Sevanto, Sanna; Vesala, Timo

    2013-03-01

    Carbon uptake and transpiration in plant leaves occurs through stomata that open and close. Stomatal action is usually considered a response to environmental driving factors. Here we show that leaf gas exchange is more strongly related to whole tree level transport of assimilates than previously thought, and that transport of assimilates is a restriction of stomatal opening comparable with hydraulic limitation. Assimilate transport in the phloem requires that osmotic pressure at phloem loading sites in leaves exceeds the drop in hydrostatic pressure that is due to transpiration. Assimilate transport thus competes with transpiration for water. Excess sugar loading, however, may block the assimilate transport because of viscosity build-up in phloem sap. Therefore, for given conditions, there is a stomatal opening that maximizes phloem transport if we assume that sugar loading is proportional to photosynthetic rate. Here we show that such opening produces the observed behaviour of leaf gas exchange. Our approach connects stomatal regulation directly with sink activity, plant structure and soil water availability as they all influence assimilate transport. It produces similar behaviour as the optimal stomatal control approach, but does not require determination of marginal cost of water parameter. PMID:22934921

  11. Leaf-wax n-alkanes record the plant–water environment at leaf flush

    PubMed Central

    Tipple, Brett J.; Berke, Melissa A.; Doman, Christine E.; Khachaturyan, Susanna; Ehleringer, James R.

    2013-01-01

    Leaf-wax n-alkanes 2H/1H ratios are widely used as a proxy in climate reconstruction. Although the broad nature of the relationship between n-alkanes δ2H values and climate is appreciated, the quantitative details of the proxy remain elusive. To examine these details under natural environmental conditions, we studied a riparian broadleaf angiosperm species, Populus angustifolia, growing on water with a constant δ2H value and monitored the δ2H values of leaf-wax n-alkanes and of stem, leaf, stream, and atmospheric waters throughout the entire growing season. Here we found the δ2H values of leaf-wax n-alkanes recorded only a 2-wk period during leaf flush and did not vary for the 19 weeks thereafter when leaves remained active. We found δ2H values of leaf-wax n-alkanes of P. angustifolia record conditions earlier in the season rather than fully integrating the entire growing season. Using these data, we modeled precipitation δ2H values during the time of wax synthesis. We observed that the isotope ratios of this precipitation generally were 2H-enriched compared with mean annual precipitation. This model provides a mechanistic basis of the often-observed 2H-enrichment from the expected fractionation values in studies of broadleaf angiosperm leaf-wax δ2H. In addition, these findings may have implications for the spatial and temporal uses of n-alkane δ2H values in paleoapplications; when both plant community and growth form are known, this study allows the isolation of the precipitation dynamics of individual periods of the growing season. PMID:23359675

  12. Family Life.

    ERIC Educational Resources Information Center

    Naturescope, 1986

    1986-01-01

    Focuses on various aspects of mammal family life ranging from ways different species are born to how different mammals are raised. Learning activities include making butter from cream, creating birth announcements for mammals, and playing a password game on family life. (ML)

  13. Life sciences

    SciTech Connect

    Day, L.

    1991-04-01

    This document is the 1989--1990 Annual Report for the Life Sciences Divisions of the University of California/Lawrence Berkeley Laboratory. Specific progress reports are included for the Cell and Molecular Biology Division, the Research Medicine and Radiation Biophysics Division (including the Advanced Light Source Life Sciences Center), and the Chemical Biodynamics Division. 450 refs., 46 figs. (MHB)

  14. Evidence to Support the Anti-Cancer Effect of Olive Leaf Extract and Future Directions

    PubMed Central

    Boss, Anna; Bishop, Karen S.; Marlow, Gareth; Barnett, Matthew P. G.; Ferguson, Lynnette R.

    2016-01-01

    The traditional Mediterranean diet (MD) is associated with long life and lower prevalence of cardiovascular disease and cancers. The main components of this diet include high intake of fruit, vegetables, red wine, extra virgin olive oil (EVOO) and fish, low intake of dairy and red meat. Olive oil has gained support as a key effector of health benefits and there is evidence that this relates to the polyphenol content. Olive leaf extract (OLE) contains a higher quantity and variety of polyphenols than those found in EVOO. There are also important structural differences between polyphenols from olive leaf and those from olive fruit that may improve the capacity of OLE to enhance health outcomes. Olive polyphenols have been claimed to play an important protective role in cancer and other inflammation-related diseases. Both inflammatory and cancer cell models have shown that olive leaf polyphenols are anti-inflammatory and protect against DNA damage initiated by free radicals. The various bioactive properties of olive leaf polyphenols are a plausible explanation for the inhibition of progression and development of cancers. The pathways and signaling cascades manipulated include the NF-κB inflammatory response and the oxidative stress response, but the effects of these bioactive components may also result from their action as a phytoestrogen. Due to the similar structure of the olive polyphenols to oestrogens, these have been hypothesized to interact with oestrogen receptors, thereby reducing the prevalence and progression of hormone related cancers. Evidence for the protective effect of olive polyphenols for cancer in humans remains anecdotal and clinical trials are required to substantiate these claims idea. This review aims to amalgamate the current literature regarding bioavailability and mechanisms involved in the potential anti-cancer action of olive leaf polyphenols. PMID:27548217

  15. Evidence to Support the Anti-Cancer Effect of Olive Leaf Extract and Future Directions.

    PubMed

    Boss, Anna; Bishop, Karen S; Marlow, Gareth; Barnett, Matthew P G; Ferguson, Lynnette R

    2016-01-01

    The traditional Mediterranean diet (MD) is associated with long life and lower prevalence of cardiovascular disease and cancers. The main components of this diet include high intake of fruit, vegetables, red wine, extra virgin olive oil (EVOO) and fish, low intake of dairy and red meat. Olive oil has gained support as a key effector of health benefits and there is evidence that this relates to the polyphenol content. Olive leaf extract (OLE) contains a higher quantity and variety of polyphenols than those found in EVOO. There are also important structural differences between polyphenols from olive leaf and those from olive fruit that may improve the capacity of OLE to enhance health outcomes. Olive polyphenols have been claimed to play an important protective role in cancer and other inflammation-related diseases. Both inflammatory and cancer cell models have shown that olive leaf polyphenols are anti-inflammatory and protect against DNA damage initiated by free radicals. The various bioactive properties of olive leaf polyphenols are a plausible explanation for the inhibition of progression and development of cancers. The pathways and signaling cascades manipulated include the NF-κB inflammatory response and the oxidative stress response, but the effects of these bioactive components may also result from their action as a phytoestrogen. Due to the similar structure of the olive polyphenols to oestrogens, these have been hypothesized to interact with oestrogen receptors, thereby reducing the prevalence and progression of hormone related cancers. Evidence for the protective effect of olive polyphenols for cancer in humans remains anecdotal and clinical trials are required to substantiate these claims idea. This review aims to amalgamate the current literature regarding bioavailability and mechanisms involved in the potential anti-cancer action of olive leaf polyphenols. PMID:27548217

  16. Hydrogen isotopes from source water to leaf lipid in a continental-scale sample network

    NASA Astrophysics Data System (ADS)

    Nelson, Daniel; Kahmen, Ansgar

    2015-04-01

    Sedimentary plant waxes are useful paleoclimate proxies because they are preserved in depositional settings on geologic timescales and the isotopic composition of the hydrogen in these molecules reflects that of the source water available during biosynthesis. This application is based largely on empirical calibrations that have demonstrated continental-scale correlations between source water and lipid hydrogen isotope values. However, the importance of variable net isotopic fractionation between source water and lipid for different species and environmental conditions is increasingly recognized. Isotopic enrichment of leaf water during transpiration is key among these secondary factors, and is itself sensitive to changes in hydroclimate. Leaf water enrichment also occurs prior to photosynthetic water uptake, and is therefore independent from cellular-level biomarker synthesis. Mechanistic models can predict the mean leaf water hydrogen isotope composition from readily available meteorological variables. This permits global-scale isoscape maps of leaf water isotopic composition and enrichment above source water to be generated, but these models have not been widely validated at continental spatial scales. We have established a network of twenty-one sites across Europe where we are sampling for leaf-, xylem-, and soil-water isotopes (H and O) at approximately 5-week intervals over the summer growing season. We augment the sample set with weekly to monthly precipitation samples and early- and late-season plant wax lipid samples. Collaborators at each site are conducting the sampling, and most sites are members of the FLUXNET tower network that also record high-resolution meteorological data. We present information on the implementation of the network and preliminary results from the 2014 summer season. The complete dataset will be used to track the evolution of water isotopes from source to leaf water and from leaf water to lipid hydrogen across diverse environments

  17. Web-based leaf water isoscapes in IsoMAP using raster modeling

    NASA Astrophysics Data System (ADS)

    Mittal, S.; West, J. B.; Bowen, G. J.; Kalangi, A.; Lee, H. J.; Miller, C.; Zhang, T.; Zhao, L.

    2011-12-01

    The isotopic composition of leaf water acts as a relatively short-term recorder of transpiration and soil moisture access, is an important driver of the δ18O of atmospheric O2 and CO2 and is also the medium in which photosynthesis occurs, affecting the isotopic composition (δ18O and δ2H) of all organic compounds produced by plants. Understanding what causes isotopic variation in leaf water is therefore of critical importance to the use of oxygen and hydrogen isotope ratios of plant materials to make inferences about a variety of processes in hydrology, ecology, atmospheric science, and paleoecology, and others. Although understanding the large-scale spatial variation in leaf water isotopic composition is particularly important for drawing inferences from several proxies, modeling the spatial variation of leaf water isotopic variation has presented challenges. Here we describe a component of a new online portal (IsoMAP; http://isomap.org) that provides researchers with tools to produce, utilize, and evaluate leaf water and other plant isoscapes. We believe that facilitating the use of plant isoscapes by a variety of researchers will enhance not only individual research efforts targeted at drawing inferences from plant hydrogen and oxygen isotope ratios, but will also facilitate a productive dialog and framework for plant physiologists interested in directly modeling the processes that drive isotopic variation in plants. IsoMAP is a web-based portal that provides users with free global access to a diverse set of tools for spatial isotopic data analysis, modeling and the generation of isoscapes. The IsoMAP plant modeling component implements three steady state models of leaf water isotope enrichment: the core "Craig-Gordon" model, a "Two-pool" model, and the "Péclet" model, giving user the opportunity for inter-model comparison completely within the web portal system. The model takes as input publicly-available climate grids and IsoMAP-generated precipitation

  18. Gravitropic basis of leaf blade nastic curvatures

    NASA Technical Reports Server (NTRS)

    Hayes, A. B.

    1982-01-01

    The curvatures produced in leaf blades by auxin treatment have been described as nastic curvatures because the initial differential growth is always enhanced on the lower side, regardless of the side of application. It is now known, however, that blades can show differential growth of either the upper or the lower side depending on the conditions of treatment. The dorsiventrality of the blade therefore influences but does not limit the direction of curvature. The dorsiventral directionality of response to growth regulators and the response to changes in the orientation to gravity are seen as indicating that blade curvatures are analogous to negative or positive gravitropism. It is noted that neither blade hyponasty or epinasty can be accounted for by ethylene alone. Petiole responses, however, are not directional, and the leaf angle changes induced by rotation or auxin treatment can be accounted for by ethylene production.

  19. 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

  20. A common genetic basis to the origin of the leaf economics spectrum and metabolic scaling allometry.

    PubMed

    Vasseur, François; Violle, Cyrille; Enquist, Brian J; Granier, Christine; Vile, Denis

    2012-10-01

    Many facets of plant form and function are reflected in general cross-taxa scaling relationships. Metabolic scaling theory (MST) and the leaf economics spectrum (LES) have each proposed unifying frameworks and organisational principles to understand the origin of botanical diversity. Here, we test the evolutionary assumptions of MST and the LES using a cross of two genetic variants of Arabidopsis thaliana. We show that there is enough genetic variation to generate a large fraction of variation in the LES and MST scaling functions. The progeny sharing the parental, naturally occurring, allelic combinations at two pleiotropic genes exhibited the theorised optimum ¾ allometric scaling of growth rate and intermediate leaf economics. Our findings: (1) imply that a few pleiotropic genes underlie many plant functional traits and life histories; (2) unify MST and LES within a common genetic framework and (3) suggest that observed intermediate size and longevity in natural populations originate from stabilising selection to optimise physiological trade-offs. PMID:22856883

  1. 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

  2. Co-ordination among leaf water relations and xylem vulnerability to embolism of Eucalyptus trees growing along a depth-to-groundwater gradient.

    PubMed

    Zolfaghar, Sepideh; Villalobos-Vega, Randol; Cleverly, James; Eamus, Derek

    2015-07-01

    The importance of groundwater resources in arid and semi-arid areas for plant survival is well documented. However, there have been few studies examining the importance and impacts of groundwater availability in mesic environments. The aim of this study was to determine how depth-to-groundwater (DGW) impacts on leaf water relations, leaf structure and branch xylem vulnerability to embolism in a mesic environment. We hypothesize that increasing DGW results in increased resistance to drought stress and that this will be manifested across leaf and branch attributes pertaining to water relations. We further investigate whether there is co-ordination across leaf and branch-scale level responses to increased DGW. Four species were used in this study: Eucalyptus globoidea Blakely, E. piperita Sm., E. sclerophylla (Blakely) L.A.S.Johnson & Blaxell and E. sieberi L.A.S.Johnson. Six sites were chosen along an 11 km transect to span a range of average DGW: 2.4, 4.3, 9.8, 13, 16.3 and 37.5 m. Leaf water relations of trees showed less sensitivity to drought stress as DGW increased. This was reflected in significantly lower leaf turgor loss point and maximum osmotic potential, increased maximum turgor and a reduced leaf relative water content as DGW increased. At shallow DGW sites, minimum diurnal leaf water potentials were generally more negative than leaf water potential at zero turgor, but the reverse was observed at deep sites, indicating a larger growth potential safety margin at deep sites compared with shallow sites. Leaf cell wall elasticity varied independently of DGW. Xylem vulnerability to embolism was quantified as the water potential associated with 50% loss of conductance (P 50). In both summer and winter P 50 was significantly and negatively correlated with DGW. Co-ordination between leaf- and branch-level responses to increase in DGW was apparent, which strongly supports the conclusion that groundwater supply influenced woodland structure and functional behaviour

  3. Toward Systems Understanding of Leaf Senescence: An Integrated Multi-Omics Perspective on Leaf Senescence Research.

    PubMed

    Kim, Jeongsik; Woo, Hye Ryun; Nam, Hong Gil

    2016-06-01

    Leaf senescence is a complex but tightly regulated developmental process involving a coordinated sequence of multiple molecular events, which ultimately leads to death of the leaf. Efforts to understand the mechanistic principles underlying leaf senescence have been largely made by transcriptomic, proteomic, and metabolomic studies over the past decade. This review focuses on recent milestones in leaf senescence research obtained using multi-omics technologies, as well as future endeavors toward systems understanding of leaf senescence processes. In particular, we discuss recent advances in understanding molecular events during leaf senescence through genome-wide transcriptome analyses in Arabidopsis. We also describe comparative transcriptome analyses used to unveil the commonality and diversity of regulatory mechanisms governing leaf senescence in the plant kingdom. Finally, we provide current illustrations of epigenomic, proteomic, and metabolomic landscapes of leaf senescence. We envisage that integration of multi-omics leaf senescence data will enable us to address unresolved questions regarding leaf senescence, including determining the molecular principles that coordinate concurrent and ordered changes in biological events during leaf senescence. PMID:27174403

  4. Planets and Life

    NASA Astrophysics Data System (ADS)

    Sullivan, Woodruff T., III; Baross, John

    2001-12-01

    Astrobiology involves the study of the origin and history of life on Earth, planets and moons where life may have arisen, and the search for extraterrestrial life. It combines the sciences of biology, chemistry, palaeontology, geology, planetary physics and astronomy. This textbook brings together world experts in each of these disciplines to provide the most comprehensive coverage of the field currently available. Topics cover the origin and evolution of life on Earth, the geological, physical and chemical conditions in which life might arise and the detection of extraterrestrial life on other planets and moons. The book also covers the history of our ideas on extraterrestrial life and the origin of life, as well as the ethical, philosophical and educational issues raised by astrobiology. Written to be accessible to students from diverse backgrounds, this text will be welcomed by advanced undergraduates and graduates who are taking astrobiology courses.• Compiled by world experts in their disciplines to create a truly comprehensive book • Accessible to students from a wide range of backgrounds • A welcome addition to this rapidly-growing field

  5. Yolk pigments of the Mexican leaf frog.

    PubMed

    Marinetti, G V; Bagnara, J T

    1983-02-25

    Eggs of the Mexican leaf frog contain blue and yellow pigments identified as biliverdin and lutein, respectively. Both pigments are bound to proteins that occur in crystalline form in the yolk platelet. The major blue pigment is biliverdin IX alpha. The eggs vary in color from brilliant blue to pale yellow-green depending on the amount of each pigment. These pigments may provide protective coloration to the eggs. PMID:6681678

  6. Phytohormones and microRNAs as sensors and regulators of leaf senescence: assigning macro roles to small molecules.

    PubMed

    Sarwat, Maryam; Naqvi, Afsar Raza; Ahmad, Parvaiz; Ashraf, Muhammad; Akram, Nudrat Aisha

    2013-12-01

    Ageing or senescence is an intricate and highly synchronized developmental phase in the life of plant parts including leaf. Senescence not only means death of a plant part, but during this process, different macromolecules undergo degradation and the resulting components are transported to other parts of the plant. During the period from when a leaf is young and green to the stage when it senesces, a multitude of factors such as hormones, environmental factors and senescence associated genes (SAGs) are involved. Plant hormones including salicylic acid, abscisic acid, jasmonic acid and ethylene advance leaf senescence, whereas others like cytokinins, gibberellins, and auxins delay this process. The environmental factors which generally affect plant development and growth, can hasten senescence, the examples being nutrient dearth, water stress, pathogen attack, radiations, high temperature and light intensity, waterlogging, and air, water or soil contamination. Other important influences include carbohydrate accumulation and high carbon/nitrogen level. To date, although several genes involved in this complex process have been identified, still not much information exists in the literature on the signalling mechanism of leaf senescence. Now, the Arabidopsis mutants have paved our way and opened new vistas to elucidate the signalling mechanism of leaf senescence for which various mutants are being utilized. Recent studies demonstrating the role of microRNAs in leaf senescence have reinforced our knowledge of this intricate process. This review provides a comprehensive and critical analysis of the information gained particularly on the roles of several plant growth regulators and microRNAs in regulation of leaf senescence. PMID:23453916

  7. 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

  8. Ancient pinnate leaf mimesis among lacewings

    PubMed Central

    Wang, Yongjie; Liu, Zhiqi; Wang, Xin; Shih, Chungkun; Zhao, Yunyun; Engel, Michael S.; Ren, Dong

    2010-01-01

    Insects have evolved diverse methods of predator avoidance, many of which implicate complex adaptations of their wings (e.g., Phylliidae, Nymphalidae, Notodontidae). Among these, angiosperm leaf mimicry is one of the most dramatic, although the historical origins of such modifications are unclear owing to a dearth of paleontological records. Here, we report evidence of pinnate leaf mimesis in two lacewings (Neuroptera): Bellinympha filicifolia Y. Wang, Ren, Liu & Engel gen. et sp. nov. and Bellinympha dancei Y. Wang, Ren, Shih & Engel, sp. nov., from the Middle Jurassic, representing a 165-million-year-old specialization between insects and contemporaneous gymnosperms of the Cycadales or Bennettitales. Furthermore, such lacewings demonstrate a preangiosperm origin for leaf mimesis, revealing a lost evolutionary scenario of interactions between insects and gymnosperms. The current fossil record suggests that this enigmatic lineage became extinct during the Early Cretaceous, apparently closely correlated with the decline of Cycadales and Bennettitales at that time, and perhaps owing to the changing floral environment resulted from the rise of flowering plants. PMID:20805491

  9. Currently available antitussives.

    PubMed

    Dicpinigaitis, Peter V

    2009-04-01

    Cough is among the most common complaints for which patients seek medical attention. Acute cough, usually due to a viral upper respiratory tract infection, generates a huge expenditure on prescription and over-the-counter cough and cold preparations worldwide. Most of these agents, however, have not been shown to be more effective than placebo in adequately performed clinical trials. The goal of management in chronic cough is treatment of its underlying cause. However, certain situations will necessitate cough suppressant therapy for symptomatic relief. Unfortunately, currently available antitussives, such as the opioids, are not consistently effective, or achieve therapeutic effect at the expense of unpleasant or intolerable side effects. Safer and more effective cough suppressants are desperately needed. Potential novel antitussives will need to be evaluated in properly formulated clinical trials, measuring relevant subjective and objective end points in appropriate subject populations. PMID:18771744

  10. Recent EPA reports available

    SciTech Connect

    1993-11-01

    The EPA reports discussed below have recently been made available through the National Technical Information Service (NTIS) or EPA`s Office Research and Development (ORD). Studies were conducted recently to determine the suitability of incineration as a treatment technology for contaminated soils and sludges from three separate Superfund sites. All of the testing was performed at EPA`s incineration research facility in Jefferson, Arkansas. The test system consists of a rotary kiln incinerator, fired afterburner, wet flue gas scrubber (a venturi section in series with a packed column), and various other air pollution control equipment. EPA`s project summaries of the three reports, including results from the pilot-scale incineration tests, are summarized below. 1 fig., 2 tabs.

  11. Magsat data availability

    NASA Technical Reports Server (NTRS)

    Langel, R. A.

    1982-01-01

    It is pointed out that a new era in near-earth magnetic field measurements began with NASA's launch of Magsat in October 1979 into a twilight, sun-synchronous orbit with 96.76 deg inclination, 561-km apogee, and 352-km perigee. A cesium vapor and a fluxgate magnetometer were employed to measure the magnetic field. A measurement of the spacecraft attitude to 20 arcseconds was required to achieve 6 nT (nanotesla) accuracy in the component measurements. This was accomplished with the aid of two star cameras on board the spacecraft and a sun sensor attached to the vector magnetometer. Magsat remained in orbit until June 11, 1980. Magsat has conducted the first truly global geomagnetic survey since the studies performed by the Polar Orbiting Geophysical Observatory (POGO) satellites. A global vector survey was provided of the main geopotential field and lower altitude measurements of crustal anomalies were conducted. Details concerning the availability of these data are discussed.

  12. Fulbright Grants available

    NASA Astrophysics Data System (ADS)

    The Council for International Exchange of Scholars (CIES) is accepting applications for the 1987-1988 Fulbright Scholar Awards. More than 300 grants in research and 700 grants in university lecturing are available for periods ranging from 3 months to a full academic year, with openings in more than 100 countries and some opportunities for research in more than one country.Fulbright awards are granted in virtually all disciplines. Scholars of all academic ranks, including retired faculty and independent scholars, are eligible to apply. Fulbright scholars must be U.S. citizens with a Ph.D. or comparable professional qualifications, have university or college teaching experience, and, for selected assignments, be proficient in a foreign language.

  13. Fulbright Grants available

    NASA Astrophysics Data System (ADS)

    The Council for International Exchange of Scholars (CIES) is accepting applications for the 1988-1989 Fulbright Scholar Awards. More than 300 grants in research and 700 grants in university lecturing are available for periods ranging from 3 months to a full academic year, with openings in more than 100 countries and some opportunities for research in more than one country.Fulbright awards are granted in virtually all disciplines. Scholars of all academic ranks, including retired faculty and independent scholars, are eligible to apply. Fulbright scholars must be U.S. citizens with a Ph.D. or comparable professional qualifications, have university or college teaching experience, and for selected assignments, be proficient in a foreign language. There is no longer a limit of two Fulbright grants to a single scholar.

  14. Stomatal Closure during Leaf Dehydration, Correlation with Other Leaf Physiological Traits1

    PubMed Central

    Brodribb, Tim J.; Holbrook, N. Michele

    2003-01-01

    The question as to what triggers stomatal closure during leaf desiccation remains controversial. This paper examines characteristics of the vascular and photosynthetic functions of the leaf to determine which responds most similarly to stomata during desiccation. Leaf hydraulic conductance (Kleaf) was measured from the relaxation kinetics of leaf water potential (Ψl), and a novel application of this technique allowed the response of Kleaf to Ψl to be determined. These “vulnerability curves” show that Kleaf is highly sensitive to Ψl and that the response of stomatal conductance to Ψl is closely correlated with the response of Kleaf to Ψl. The turgor loss point of leaves was also correlated with Kleaf and stomatal closure, whereas the decline in PSII quantum yield during leaf drying occurred at a lower Ψl than stomatal closure. These results indicate that stomatal closure is primarily coordinated with Kleaf. However, the close proximity of Ψl at initial stomatal closure and initial loss of Kleaf suggest that partial loss of Kleaf might occur regularly, presumably necessitating repair of embolisms. PMID:12913171

  15. Quantification of uncertainties in fossil leaf paleoaltimetry: Does leaf size matter?

    NASA Astrophysics Data System (ADS)

    Spicer, Robert A.; Yang, Jian

    2010-12-01

    The utility of multivariate foliar physiognomy, specifically the Climate Leaf Analysis Multivariate Program (CLAMP), to yield reliable estimates of enthalpy and, hence, paleoelevation has been demonstrated by comparison with other proxies, yet concerns have arisen regarding uncertainties arising from (1) apparent ambiguities in the scoring regime and (2) the way leaf size is scored. Regarding the first concern, scoring ambiguities are examined by reporting on scoring tests with novice users and interlaboratory comparisons. The uncertainties were found to be less than those arising from the statistical methodology underpinning CLAMP. In respect to the second concern, the effect of removing all size data both from modern test sites and fossil data was tested. Specifically, the effect of removing leaf size data from the 15 Ma Namling data set from south central Tibet was investigated. Removal of all size data from modern sites demonstrated that size data contributes little to estimates of mean annual temperature and enthalpy. Similarly, the removal of leaf size information from the Namling data set alone, but with calibration unchanged, and from both the Namling site and calibration sites, this time with recalibration, still yield paleoelevation estimates that have been independently matched by oxygen isotope techniques. Moreover, the removal of all leaf size information results in only small increases in uncertainty (±52 m).

  16. Leaf volatile emissions of Betula pendula during autumn coloration and leaf fall.

    PubMed

    Holopainen, Jarmo K; Heijari, Juha; Oksanen, Elina; Alessio, Giorgio A

    2010-10-01

    Deciduous trees remobilize the nitrogen in leaves during the process of autumn coloration, thus providing a high quality food source for aphids preparing to lay over-wintering eggs. It has been suggested that aphids may use volatile organic compounds (VOCs) to: (a) select leaves where nutrient remobilization has started and induced defenses are reduced; and (b) detect the time of leaf abscission. We analyzed VOCs emitted by the foliage of Betula pendula Roth. during autumn coloration and from leaf litter just after leaf fall. We tested the hypothesis that costly, photosynthesis-related terpenes and other herbivore-induced VOCs related to attraction of aphid parasitoids and predators are reduced during the coloration process. We also investigated if the VOC emission profile of abscising leaves is different from that of early stage yellowing leaves. Enemy-luring compounds (E)-β-ocimene, linalool, and (E)-4,8-dimethyl-1,3,7-nonatriene (DMNT) were emitted only from the green foliage. Methyl salicylate (MeSa), known to recruit predatory bugs and attract migrant aphids, was emitted until the first stage of color change. Cis-3-hexenol, an indicator of cellular disintegration, became dominant in the emissions from abscising leaves and from fresh leaf litter. We discuss the ecological significance of the observed changes in birch leaf VOC profiles during the process of autumn senescence. PMID:20838885

  17. 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

  18. Life's timekeeper.

    PubMed

    Neill, David

    2013-03-01

    Life's timekeeper is a 'free-running' intracellular oscillator synchronised across all cells. It runs throughout life splitting lifespan into equal length phases. During the maturational period it controls the overall rate of progression whereas in the post-maturational period it controls the overall rate of ageing. This includes the rate of senescence and hence time to death. As such life's timekeeper equates maturational and post-maturational time, hence explains the tight correlation between these time periods that has existed throughout mammalian evolution. Life's timekeeper is proposed to have played an important role in vertebrate evolution. A slower oscillatory frequency results in proportional life phase prolongation. This leads to increased body and brain size, together with extended lifespan. Higher brain centres, neocortex in mammals, are disproportionately enlarged. Hence behavioural capacity is increased. The extended post-maturational period ensures that there is enough time in order that the behavioural advantages can be fully manifest in the environment. A faster oscillatory frequency would result in proportional life phase reduction. This process however would lead to reduced behavioural capacity, and is hence unlikely to be positively selected. Therefore throughout evolution life's timekeeper has operated to extend lifespan. It has hence functioned to promote longevity as opposed to ageing. PMID:23354279

  19. 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

  20. An empirical model that uses light attenuation and plant nitrogen status to predict within-canopy nitrogen distribution and upscale photosynthesis from leaf to whole canopy

    PubMed Central

    Louarn, Gaëtan; Frak, Ela; Zaka, Serge; Prieto, Jorge; Lebon, Eric

    2015-01-01

    Modelling the spatial and temporal distribution of leaf nitrogen (N) is central to specify photosynthetic parameters and simulate canopy photosynthesis. Leaf photosynthetic parameters depend on both local light availability and whole-plant N status. The interaction between these two levels of integration has generally been modelled by assuming optimal canopy functioning, which is not supported by experiments. During this study, we examined how a set of empirical relationships with measurable parameters could be used instead to predict photosynthesis at the leaf and whole-canopy levels. The distribution of leaf N per unit area (Na) within the canopy was related to leaf light irradiance and to the nitrogen nutrition index (NNI), a whole-plant variable accounting for plant N status. Na was then used to determine the photosynthetic parameters of a leaf gas exchange model. The model was assessed on alfalfa canopies under contrasting N nutrition and with N2-fixing and non-fixing plants. Three experiments were carried out to parameterize the relationships between Na, leaf irradiance, NNI and photosynthetic parameters. An additional independent data set was used for model evaluation. The N distribution model showed that it was able to predict leaf N on the set of leaves tested. The Na at the top of the canopy appeared to be related linearly to the NNI, whereas the coefficient accounting for N allocation remained constant. Photosynthetic parameters were related linearly to Na irrespective of N nutrition and the N acquisition mode. Daily patterns of gas exchange were simulated accurately at the leaf scale. When integrated at the whole-canopy scale, the model predicted that raising N availability above an NNI of 1 did not result in increased net photosynthesis. Overall, the model proposed offered a solution for a dynamic coupling of leaf photosynthesis and canopy N distribution without requiring any optimal functioning hypothesis. PMID:26433705