Sample records for plant transpiration rate

  1. Transpiration rates of rice plants treated with Trichoderma spp.

    NASA Astrophysics Data System (ADS)

    Doni, Febri; Anizan, I.; Che Radziah C. M., Z.; Yusoff, Wan Mohtar Wan

    2014-09-01

    Trichoderma spp. are considered as successful plant growth promoting fungi and have positive role in habitat engineering. In this study, the potential for Trichoderma spp. to regulate transpiration process in rice plant was assessed experimentally under greenhouse condition using a completely randomized design. The study revealed that Trichoderma spp. have potential to enhance growth of rice plant through transpirational processes. The results of the study add to the advancement of the understanding as to the role of Trichoderma spp. in improving rice physiological process.

  2. Effect of transpiration rate on internal plant resistance to water flow

    E-print Network

    Hailey, James Lester

    1971-01-01

    in the flowering stagei were subjected to a constant environment except for step-wise changes in relative humidity to obtain different transpiration rates. The transpiration rate was in all cases linearly re- lated to the leaf water potential~ for the range... models for liquid water flow in plants. because it enables one to estimate leaf water potential from known or estimated transpiration rates. The predicted leaf water potential can be used for scheduling irrigation ~ The leaf diffusion resistance...

  3. Triazoles : Their Effects on Net Photosynthetic Rate, Transpiration Rate and Stomatal Resistance in Setaria italica Plants grown in vivo

    Microsoft Academic Search

    Rhadha Bisht; Premlata Singariya; Navish Mathur; S. P. Bohra

    The effects of different concentration of triazoles (Triademefon (TDM) and Paclobutrazol (PBZ)) on net photosynthetic rate, transpiration rate and stomatal resistance were studied in Setaria italica plants grown under field conditions. Net photosynthetic rates (Pn), transpiration rates (Tr) and stomatal resistances (Sr) were recorded after second and fifth day of third treatment. Plants treated with triadimefon (5 and 10mg\\/liter) and

  4. Plant Cycles: Photosynthesis & Transpiration

    NSDL National Science Digital Library

    2014-09-18

    What do plants need? Students examine the effects of light and air on green plants, learning the processes of photosynthesis and transpiration. Student teams plant seeds, placing some in sunlight and others in darkness. They make predictions about the outcomes and record ongoing observations of the condition of the stems, leaves and roots. Then, several healthy plants are placed in glass jars with lids overnight. Condensation forms, illustrating the process of transpiration, or the release of moisture to the atmosphere by plants.

  5. Just Breathe Green: Measuring Transpiration Rates

    NSDL National Science Digital Library

    2014-09-18

    Through multi-trial experiments, students are able to see and measure something that is otherwise invisible to them—seeing plants breathe. Student groups are given two small plants of native species and materials to enclose them after watering with colored water. After being enclosed for 5, 10 and 15 minutes, teams collect and measure the condensed water from the plants' "breathing," and then calculate the rates at which the plants breathe. A plant's breath is known as transpiration, which is the flow of water from the ground where it is taken up by roots (plant uptake) and then lost through the leaves. Students plot volume/time data for three different native plant species, determine and compare their transpiration rates to see which had the highest reaction rate and consider how a plant's unique characteristics (leaf surface area, transpiration rate) might figure into engineers' designs for neighborhood stormwater management plans.

  6. Zinc and copper uptake by plants under two transpiration rates. Part II. Buckwheat (Fagopyrum esculentum L.).

    PubMed

    Tani, F H; Barrington, S

    2005-12-01

    To evaluate the environmental risks of irrigating crops with treated wastewater, a study was undertaken to quantify heavy metal uptake by 4-week old buckwheat (Fagopyrum esculentum L.) plants during 18 days of irrigation with 8 different Cu and Zn solutions under two transpiration rates (TR). At 4 weeks, potted buckwheat plants were transferred into one of the two growth chambers, offering either a high or low vapour pressure deficit (VDP) for, respectively, a high or low TR. Triplicate pots received one of the 8 irrigation treatments containing one of two Zn levels (0 and 25 mg/L) combined with one of four Cu levels (0, 5, 10 and 15 mg/L). Daily TR were measured by weighing the evapo-transpired water lost from the planted pot, less was the evaporation loss measured from triplicate non-planted pots. After 0, 6, 12 and 18 days of treatment, the stems and leaves of three randomly selected plants were harvested and after 18 days, the roots were harvested to determine Cu and Zn uptake. The treatments did not affect TR in terms of dry plant mass, indicating the absence of toxic effects. Irrigating with Zn, without Cu, increased dry biomass production, whereas the lowest biomass occurred with 15 and 30 mg/L of Cu with and without 25 mg/L of Zn, respectively, because higher applications of heavy metal significantly reduced soil pH. Plant Cu and Zn uptake increased with TR. With higher levels of Cu, Zn uptake by buckwheat was significantly reduced, while Zn had a slight but non-significant impact on Cu uptake. Previously and in a study exposing wheat plants to the same conditions, Cu significantly increased Zn uptake, while Zn had a slight but insignificant negative effect on Cu uptake. The buckwheat roots contained the greatest levels of Cu and Zn, indicating their role in moderating heavy metal uptake. Also, both Cu and Zn had a synergetic effect on each other in terms of root levels, and a similar observation was made in the earlier similar experiment using wheat plants. Irrigating a buckwheat crop with treated wastewater, with more natural Cu and Zn levels of 0.08 mg/L, could be quite beneficial without endangering the quality of the crop and acidifying the soil pH. The most concentrated experimental solutions contained 300 times more Cu and Zn, to obtain measurable differences. PMID:16043272

  7. Ozone. Effect on apparent photosynthesis, rate of transpiration, and stomatal closure in plants

    Microsoft Academic Search

    A. Clyde Hill; Niel Littlefield

    1969-01-01

    Little is known regarding the cause of plant growth suppression resulting from photochemical pollution. Studies with ozone indicate that elevated ozone concentrations may be involved. Ozone induced partial stomatal closure and a reduction in apparent photosynthesis and transpiration. High concentrations of ozone caused a temporary reduction in apparent photosynthesis of many species, often with little or no injury developing. The

  8. Plant transpiration distillation of water

    SciTech Connect

    Virostko, M.K.; Spielberg, J.I.

    1986-01-01

    A project using solar energy and the transpiration of plants for the distillation of water is described. Along with determining which of three plants thrived best growing in a still, the experiment also revealed that the still functioned nearly as well in inclement weather as in fair weather.

  9. Transpiration: Water Movement Through Plants

    NSDL National Science Digital Library

    Tracy Sterling (New Mexico State University; )

    2005-09-23

    Learn the basics of transpiration -- the transportation of water through plants from soil to leaves to atmosphere -- with this playful animation created by weed physiologist Tracy Sterling and animator Matt Byrnes. Interactive features allow you to explore the process including how changing environmental conditions can impact how fast water moves.

  10. Daily transpiration rates of woody species on drying soil.

    PubMed

    Sinclair, Thomas R; Holbrook, N Michelle; Zwieniecki, Maciej A

    2005-11-01

    Among annual plants, daily transpiration rates, expressed as a fraction of volumetric soil water content available for transpiration, show a common pattern in response to soil drying. Initially, as soil dries, there is little decrease in transpiration rate until water availability has fallen to about one third that at field capacity. With further soil drying, relative transpiration rate decreases in a more-or-less linear fashion until all available water has been used. Data previously obtained for perennial woody species have often been confounded by different methods for determining available soil water. In this study, we investigated the daily transpiration response to soil drying in five woody perennial species: Thuja plicata Donn ex D. Don, Acer rubrum L., Robinia pseudoacacia L., Hibiscus sp. and Ibex aquifolium L. Transpiration was unaffected by soil drying until the initial estimated transpirable soil water fraction had decreased to between 0.23 and 0.32 of that at field capacity. Beyond this point, transpiration rate declined linearly with available soil water fraction until reaching one fifth the rate observed in well-watered plants. With further soil drying, the relative transpiration rates remained between 10 and 20% of that observed in well-watered plants. Maintenance of transpiration at these rates with further soil drying was hypothesized to result from contributions to transpiration of water stored in plant tissues. After taking tissue water storage into account, it was estimated that transpiration was curtailed as the available soil water fraction fell to between 0.26 and 0.37 of that at field capacity, which is comparable to values reported for annual crop plants. PMID:16105814

  11. Zinc uptake by young wheat plants under two transpiration regimes

    SciTech Connect

    Grifferty, A.; Barrington, S.

    2000-04-01

    Treated wastewater for crop irrigation is an alternative for countries with a shortage of fresh water. Such practice requires strict wastewater application criteria and a better understanding of the effects of transpiration rate on plant heavy metal uptake. The experiment measured Zn uptake by young wheat plants (Triticum aestvum L.) grown in triplicated experimental pots and held in two growth chambers with constant environmental conditions (relative humidity, light and temperature) but with a different air water vapor pressure deficit to produce two different transpiration rates. After 5 wk of growth in a greenhouse, the plants were transferred to the controlled chambers and irrigated using a fertilized solution with five different levels of Zn: 0, 2, 10, 25, and 50 mg/L. These Zn levels were low enough to have no significant effect on plant growth and transpiration rate. The wheat plants started to produce their grain at 6 wk. Plants were collected at 0, 3, and 10 d of incubation in the controlled chambers and analyzed for dry matter and total Zn content. The pots were weighed daily to measure their transpiration rates. On Day 10, the remaining plants were collected and their roots, shoots, and grain were separated, weighed, dried, and analyzed for total Zn. Time and plant transpiration rate were found to affect significantly plant Zn uptake. The higher transpiration rate enhanced plant Zn uptake. The roots had the highest Zn uptake followed by the shoots and then the grain.

  12. Quality assessment of plant transpiration water

    NASA Technical Reports Server (NTRS)

    Macler, Bruce A.; Janik, Daniel S.; Benson, Brian L.

    1990-01-01

    It has been proposed to use plants as elements of biologically-based life support systems for long-term space missions. Three roles have been brought forth for plants in this application: recycling of water, regeneration of air and production of food. This report discusses recycling of water and presents data from investigations of plant transpiration water quality. Aqueous nutrient solution was applied to several plant species and transpired water collected. The findings indicated that this water typically contained 0.3-6 ppm of total organic carbon, which meets hygiene water standards for NASA's space applications. It suggests that this method could be developed to achieve potable water standards.

  13. Effects of gravity on transpiration of plant leaves.

    PubMed

    Hirai, Hiroaki; Kitaya, Yoshiaki

    2009-04-01

    To clarify effects of gravity on the water vapor exchange between plants and the ambient air, we evaluated the transpiration rate of plant leaves at 0.01, 1.0, and 2.0 g for 20 s each during parabolic airplane flights. The transpiration rates of a strawberry leaf and a replica leaf made of wet cloth were determined using a chamber method with humidity sensors. Absolute humidity at 3 and 8 mm below the lower surface of leaves was measured to evaluate the effect of gravity on humidity near leaves and estimate their transpiration rate. The transpiration rate of the replica leaf decreased by 42% with decreasing gravity levels from 1.0 to 0.01 g and increased by 31% with increasing gravity levels from 1.0 to 2.0 g. Absolute humidity near the intact strawberry leaf was 5 g m(-3) at ambient absolute humidity of 2.3 g m(-3) and gravity of 1.0 g. The absolute humidity increased by 2.5 g m(-3) with decreasing gravity levels from 1.0 to 0.01 g. The transpiration rate of the intact leaf decreased by 46% with decreasing gravity levels from 1.0 to 0.01 g and increased by 32% with increasing gravity levels from 1.0 to 2.0 g. We confirmed that the transpiration rate of leaves was suppressed by retarding the water vapor transfer due to restricted free air convection under microgravity conditions. PMID:19426314

  14. Responses of gas exchange to reversible changes in whole-plant transpiration rate in two conifer species.

    PubMed

    Warren, C R; Livingston, N J; Turpin, D H

    2003-08-01

    This study examined the autonomy of branches with respect to the control of transpiration (E) in Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) and western red cedar (Thuja plicata Donn) seedlings. Experiments were conducted on whole seedlings in a gas exchange system with a dual-cuvette that permitted independent manipulation and measurement of E in the upper and lower cuvettes. The value of E in one cuvette was manipulated by varying vapor pressure deficit (D) between 2.2 and 0.2 kPa, whereas D in the other cuvette was held at 2.2 kPa. Reducing D, while increasing stomatal conductance (gs), resulted in an overall decrease in E. In western red cedar, this decrease was almost threefold, and in Douglas-fir, approximately fourfold. In well-watered western red cedar, a reduction of whole-plant E by 46% (brought about by reducing D in the upper cuvette) resulted in a 12% increase in gs, a 12% increase in E and a 7% increase in net assimilation (A) of untreated foliage in the lower cuvette. Responses of gs, E and A of untreated foliage were similar irrespective of whether foliage was at the top or bottom of the seedling. When D in the treatment cuvette was restored to 2.2 kPa, gs, E and A of foliage in the untreated cuvette returned to pretreatment values. In contrast, in well-watered Douglas-fir, there was almost no change in gs, E or A of untreated foliage in one cuvette when D in the other cuvette was reduced, causing a 52% reduction in whole-plant E. However, similar manipulations on drought-stressed Douglas-fir led to 7-19% increases in gs, E and A of untreated foliage. In well-watered western red cedar, daytime leaf water potential (Psil) was maintained near -0.9 MPa over a wide range of D, whereas Psil of Douglas-fir decreased from -1.2 to -1.5 MPa as D increased. The tighter (isohydric) regulation of Psil in western red cedar may partly explain its greater stomatal response to D and variation in whole-plant E compared with Douglas-fir. In response to a reduction in E, measured increases in Psil and gs of unmanipulated foliage were less than predicted by a model assuming complete hydraulic connectivity of foliage. Our results suggest the foliage of both species is partially autonomous with respect to water. PMID:12865245

  15. Transpiration - Water Movement through Plants

    NSDL National Science Digital Library

    This lesson and its animation follows the journey of water through a plant from its uptake by roots to its evaporation from the leaf surface. How this journey is altered by plant characteristics such as stomata and cuticles as well as by changes in the environment will be described.

  16. Characterizing photosynthesis and transpiration of plant communities in controlled environments

    NASA Technical Reports Server (NTRS)

    Monje, O.; Bugbee, B.

    1996-01-01

    CO2 and water vapor fluxes of hydroponically grown wheat and soybean canopies were measured continuously in several environments with an open gas exchange system. Canopy CO2 fluxes reflect the photosynthetic efficiency of a plant community, and provide a record of plant growth and health. There were significant diurnal fluctuations in root and shoot CO2 fluxes, and in shoot water vapor fluxes. Canopy stomatal conductance (Gc) to water vapor was calculated from simultaneous measurements of canopy temperature (Tcan) and transpiration rates (Tr). Tr in the dark was substantial, and there were large diurnal fluctuations in both Gc and Tr. Canopy net Photosynthesis (Pnet), Tr, and Gc increased with increasing net radiation. Gc increased with Tr, suggesting that the stomata of plants in controlled environments (CEs) behave differently from field-grown plants. A transpiration model based on measurements of Gc was developed for CEs. The model accurately predicted Tr from a soybean canopy.

  17. How-to-Do-It: Using Computers in Measuring Transpiration Rate.

    ERIC Educational Resources Information Center

    Seligmann, Peter F.; Thompson, Steven R.

    1989-01-01

    Described is an activity in which a computer is used to acquire temperature and humidity data useful in investigating transpiration in plants. Materials and procedures are discussed and examples of results are presented. Factors which influence the rate of transpiration are discussed. (CW)

  18. Measuring Transpiration to Regulate Winter Irrigation Rates

    SciTech Connect

    Samuelson, Lisa [Auburn University] [Auburn University

    2006-11-08

    Periodic transpiration (monthly sums) in a young loblolly pine plantation between ages 3 and 6 was measured using thermal dissipation probes. Fertilization and fertilization with irrigation were better than irrigation alone in increasing transpiration of young loblolly pines during winter months, apparently because of increased leaf area in fertilized trees. Irrigation alone did not significantly increase transpiration compared with the non-fertilized and non-irrigated control plots.

  19. Measuring and Modeling Interactions Between Groundwater, Soil Moisture, and Plant Transpiration in Natural and Agricultural Ecosystems

    E-print Network

    Rubin, Yoram

    Measuring and Modeling Interactions Between Groundwater, Soil Moisture, and Plant Transpiration Transpiration in Natural and Agricultural Ecosystems © 2009 by Gretchen Rose Miller #12;1 Abstract Measuring and Modeling Interactions Between Groundwater, Soil Moisture, and Plant Transpiration in Natural

  20. The porous media model for the hydraulic system of a conifer tree: linking sap flux data to1 transpiration rate2

    E-print Network

    Soatto, Stefano

    transpiration rate2 Yao-Li Chuang(1,2) , Ram Oren(3) , Andrea L. Bertozzi(1,2,4) , Nathan Phillips(5) , Gabriel #12;2 Abstract1 Linking sap flow in tree boles to plant transpiration continues to be a fundamental conversion of14 sap flow to transpiration rate during daytime. In addition to fully simulating the PDE, we

  1. Root water compensation sustains transpiration rates in an Australian woodland

    NASA Astrophysics Data System (ADS)

    Verma, Parikshit; Loheide, Steven P.; Eamus, Derek; Daly, Edoardo

    2014-12-01

    We apply a model of root-water uptake to a woodland in Australia to examine the regulation of transpiration by root water compensation (i.e., the ability of roots to regulate root water uptake from different parts of the soil profile depending on local moisture availability). We model soil water movement using the Richards equation and water flow in the xylem with Darcy's equation. These two equations are coupled by a term that governs the exchange of water between soil and root xylem as a function of the difference in water potential between the two. The model is able to reproduce measured diurnal patterns of sap flux and results in leaf water potentials that are consistent with field observations. The model shows that root water compensation is a key process to allow for sustained rates of transpiration across several months. Scenarios with different root depths showed the importance of having a root system deeper than about 2 m to achieve the measured transpiration rates without reducing the leaf water potential to levels inconsistent with field measurements. The model suggests that the presence of more than 5 % of the root system below 0.6 m allows trees to maintain sustained transpiration rates keeping leaf water potential levels within the range observed in the field. According to the model, a large contribution to transpiration in dry periods was provided by the roots below 0.3 m, even though the percentage of roots at these depths was less than 40 % in all scenarios.

  2. Transpiration in seven plant species colonizing a fishpond shore

    Microsoft Academic Search

    J. Kv?t

    1975-01-01

    In 7 species (Eleocharis palustris\\u000a R. Br.,Juncus bufonius L.,Gypsophila muralis L.,Trifolium repens L.,Agrostis stolonifera L.,Potentilla anserina L. andAchillea millefolium L.) growing in a gradient of habitats from aquatic to terrestrial, on a sandy fishpond shore in Southern Bohemia, Czechoslovakia,\\u000a the daily course of transpiration rate and water content was assessed gravimetrically in their cut-off transpiring parts on\\u000a two typical summer

  3. Past and future scenarios of the effect of carbon dioxide on plant growth and transpiration for

    E-print Network

    Paris-Sud XI, Université de

    Past and future scenarios of the effect of carbon dioxide on plant growth and transpiration a direct effect on plant transpiration. On one hand, the carbon fertilization yields an increase and transpiration reduction. Daily values of LAI and biomass can be produced by ISBA-A-gs. A previous study showed

  4. This figure shows annual transpiration rates in the Argentinean Pampas (circles and lines) under two land uses: perennial alfalfa pasture, widespread until the early nineties, and annual wheat-soybean-maize

    E-print Network

    Nacional de San Luis, Universidad

    This figure shows annual transpiration rates in the Argentinean Pampas (circles and lines) under-soybean-maize rotations, the dominant land use today.Transpiration rates (right-hand axis) are higher under pastures than as a reservoir that supports crop yields even in dry years.The balance between water loss by plant transpiration

  5. A method to determine plant water source using transpired water

    NASA Astrophysics Data System (ADS)

    Menchaca, L. B.; Smith, B. M.; Connolly, J.; Conrad, M.; Emmett, B.

    2007-04-01

    A method to determine the stable isotope ratio of a plant's water source using the plant's transpired water is proposed as an alternative to standard xylem extraction methods. The method consists of periodically sampling transpired waters from shoots or leaves enclosed in sealed, transparent bags which create a saturated environment, preclude further evaporation and allow the progressive mixing of evaporated transpired water and un-evaporated xylem water. The method was applied on trees and shrubs coexisting in a non-irrigated area where stable isotope ratios of local environmental waters are well characterized. The results show Eucalyptus globulus (tree) and Genista monspessulana (shrub) using water sources of different isotopic ratios congruent with groundwater and soil water respectively. In addition, tritium concentrations indicate that pine trees (Pinus sylvestris) switch water source from soil water in the winter to groundwater in the summer. The method proposed is particularly useful in remote or protected areas and in large scale studies related to water management, environmental compliance and surveillance, because it eliminates the need for destructive sampling and greatly reduces costs associated with laboratory extraction of xylem waters from plant tissues for isotopic analyses.

  6. The effectiveness of a foliar spray of kaolinite clay in reducing transpiration of cotton plants

    E-print Network

    McMichael, Bobbie Lee

    1967-01-01

    of approximately 50 tons of water per acre per day, from Egyptian cotton or about 3 pints per plant. Obviously a functional method to reduce transpira- tion would lower the amount of water needed to successfully grow a crop As mentioned before, many external... environmental i'actors cause rapid and drastic changes in the transpiration. rate. The effect of these factors on plant water losses must be considered before trans- piration can be successfully reduced and controlled, Temperature, and solar radiation...

  7. Photosynthesis, transpiration and water use efficiency of four plant species with grazing intensities in Hunshandak Sandland, China

    Microsoft Academic Search

    Y. Peng; G. M. Jiang; X. H. Liu; S. L. Niu; M. Z. Liu; D. K. Biswas

    2007-01-01

    In order to explore the response patterns of gas exchange to the increased grazing intensity and to test whether or not plants have compensatory growth under animal grazing disturbance, we have conducted this experiment in Hunshandak Sandland of Northern China. Changes in net photosynthetic rate (Pn), transpiration rate (E), and water use efficiency (WUE) of four plant species (Cleistogenes squarrosa,

  8. Investigation of transpiration and/or accumulation of volatile organic compounds (VOCs) by plants

    SciTech Connect

    Goodrich, R.L.; Carlsen, T.M. [Lawrence Livermore National Lab., CA (United States)

    1994-12-31

    The authors are in the planning stages of an investigation to explore plant transpiration and/or accumulation of VOCs (primarily Trichloroethylene [TCE]) by native vegetation. Such processes may naturally remediate these compounds in shallow ground water. To adequately quantify the amount of TCE in ground water prior to vegetation uptake, the authors will first install shallow piezometers adjacent to existing vegetation. Vegetation sampling will be synchronized with the ground water sampling to establish baseline conditions. They will conduct a literature search to identify potential structures with high lipid content in the plant species of interest (Populus fremontii, Typha latifolia and Salix). To investigate VOC distribution in the plant, individual morphological segments of the plant will be analyzed. The vegetation will be dissected into distinct segments, such as the vegetative (stem and leaves) and reproductive structures, to determine the possible accumulation of TCE at various points within the plant. They have completed preliminary development of analytical methods that they will use to analyze the samples. In the field, plastic (Tedlar) bags will be tightly secured onto the vegetation and a direct head-space analysis will be conducted on the bags, thus providing information on the rate of transpiration compared to the actual accumulation of VOCs within the plant. At a minimum, they expect to document VOC losses from the ground water via plant transpiration.

  9. Abstract--Plant productivity is often estimated using precipita-tion, evapotranspiration, or transpiration as a predictor for plant

    E-print Network

    , or transpiration as a predictor for plant water use. Hydrologic models are used to calculate a water bal- ance and to estimate evapotranspiration and transpiration. The water balance approach accounts for first order and plant transpiration for the time period (mm), and L = percolation or seepage below the root zone

  10. Development of the deuterium tracing method for the estimation of transpiration rates and transpiration parameters of trees

    SciTech Connect

    Calder, I.R. [Inst. of Hydrology, Wallingford (United Kingdom)

    1992-12-31

    Recent developments relating to the theory and practice of the deuterium tracing method are reviewed. Theoretical developments have shown that the method is applicable to the fluctuating flow regime which occurs in trees and that the method provides an estimate of the weighted mean flow over the time period that the tracer is present at the sampling point. A practical development of the method for estimating transpiration rates and transpiration parameters which uses time averaged sampling is described and it is shown that with this method only one deuterium tracer concentration analysis is required per tree compared with 90 using an earlier method. The calculation of surface resistance through solution of the convolution integral of the transpiration rate and the tracer concentration-time curve is also described and the sensitivity of the surface resistance estimate to the flow parameters is investigated using as an example observations made on a three year old plantation of Eucalyptus tereticornis growing in Karnataka, southern India.

  11. A Transpiration Experiment Requiring Critical Thinking Skills.

    ERIC Educational Resources Information Center

    Ford, Rosemary H.

    1998-01-01

    Details laboratory procedures that enable students to understand the concept of how differences in water potential drive the movement of water within a plant in response to transpiration. Students compare transpiration rates for upper and lower surfaces of leaves. (DDR)

  12. Field determintation of young acid lime plants transpiration by the stem heat balance method

    Microsoft Academic Search

    Maurício Antonio Coelho Filho; Luiz Roberto Angelocci; Luís Fernando de Souza Magno Campeche; Marcos Vinícius Folegatti; Marcos Silveira Bernardes

    2005-01-01

    The stem heat balance method (HBM) measures sap flow (SF) in plants, and can be used to estimate daily transpiration flow. It is a powerful technique for water relations and irrigation field studies, but it has to be tested in species of particular interest. This paper discusses effectiveness of the HBM to estimate transpiration of young acid lime plants (Citrus

  13. NOTE / NOTE Transpiration-dependent passive silica

    E-print Network

    Kitajima, Kaoru

    NOTE / NOTE Transpiration-dependent passive silica accumulation in cucumber (Cucumis sativus) under transport Si, through transpiration, from soils to shoots, while others actively transport silica manipulated transpiration rates by changing humidity and air movements around pot-grown plants receiving

  14. Determining the transpiration rate of peach trees under two trickle irrigation regimes

    E-print Network

    Rodrigue, Paul Bryan

    1980-01-01

    DETERMINING THE TRANSPIRATION RATE OF PEACH TREES UNDER TWO TRICKLE IRRIGATION REGIMES A Thesis by PAUL BRYAN RODRIGUE Submitted to the Graduate College of Texas ASM University in partial fulfillment of the requirement for the degree... of MASTER OF SCIENCE December 1980 Major Subject: Agricultural Engineering DETERMINING THE TRANSPIRATION RATE OF PEACH TREES UNDER TWO TRICKLE IRRIGATION REGIMES A Thesis by PAUL BRYAN RODRIGUE Approved as to style and content by: (Chairman...

  15. Original article Growth dynamics, transpiration and water-use

    E-print Network

    Paris-Sud XI, Université de

    Original article Growth dynamics, transpiration and water-use efficiency in Quercus robur plants was 40% of the well-watered plants transpiration in both [CO2]) conditions. In the droughted conditions in biomass growth and in plant leaf area was brought about by the elevated [CO2]. Transpiration rate

  16. Plant, Cell and Environment (1993) 16,429-436 Stomatai and environmentai controi of transpiration in a

    E-print Network

    Holbrook, N. Michele

    Plant, Cell and Environment (1993) 16,429-436 Stomatai and environmentai controi of transpiration ABSTRACT Stomatal control of crown transpiration was studied in Anacardium excelsum, a large of transpiration to a marginal change in stomatal conductance to be evaluated using a dimensionless coupling

  17. VARIABLE DISTRIBUTIONS OF WATER AS A TRANSPIRATION SOURCE: CONSEQUENCES FROM THE TREE STEM TO ECOSYSTEM FUNCTIONING

    E-print Network

    Teskey, Robert O.

    VARIABLE DISTRIBUTIONS OF WATER AS A TRANSPIRATION SOURCE: CONSEQUENCES FROM THE TREE STEM distributions of water used for transpiration can have consequences on estimates of plant and ecosystem transpiration, as well as on the production potential and stability of transpiration rates for different plants

  18. A Microfluidic Pump/Valve Inspired by Xylem Embolism and Transpiration in Plants

    PubMed Central

    Jingmin, Li; Chong, Liu; Zheng, Xu; Kaiping, Zhang; Xue, Ke; Liding, Wang

    2012-01-01

    In plants, transpiration draws the water upward from the roots to the leaves. However, this flow can be blocked by air bubbles in the xylem conduits, which is called xylem embolism. In this research, we present the design of a biomimetic microfluidic pump/valve based on water transpiration and xylem embolism. This micropump/valve is mainly composed of three parts: the first is a silicon sheet with an array of slit-like micropores to mimic the stomata in a plant leaf; the second is a piece of agarose gel to mimic the mesophyll cells in the sub-cavities of a stoma; the third is a micro-heater which is used to mimic the xylem embolism and its self-repairing. The solution in the microchannels of a microfluidic chip can be driven by the biomimetic “leaf” composed of the silicon sheet and the agarose gel. The halting and flowing of the solution is controlled by the micro-heater. Results have shown that a steady flow rate of 1.12 µl/min can be obtained by using this micropump/valve. The time interval between the turning on/off of the micro-heater and the halt (or flow) of the fluid is only 2?3 s. This micropump/valve can be used as a “plug and play” fluid-driven unit. It has the potential to be used in many application fields. PMID:23209709

  19. FPGA-based Fused Smart Sensor for Real-Time Plant-Transpiration Dynamic Estimation

    PubMed Central

    Millan-Almaraz, Jesus Roberto; de Jesus Romero-Troncoso, Rene; Guevara-Gonzalez, Ramon Gerardo; Contreras-Medina, Luis Miguel; Carrillo-Serrano, Roberto Valentin; Osornio-Rios, Roque Alfredo; Duarte-Galvan, Carlos; Rios-Alcaraz, Miguel Angel; Torres-Pacheco, Irineo

    2010-01-01

    Plant transpiration is considered one of the most important physiological functions because it constitutes the plants evolving adaptation to exchange moisture with a dry atmosphere which can dehydrate or eventually kill the plant. Due to the importance of transpiration, accurate measurement methods are required; therefore, a smart sensor that fuses five primary sensors is proposed which can measure air temperature, leaf temperature, air relative humidity, plant out relative humidity and ambient light. A field programmable gate array based unit is used to perform signal processing algorithms as average decimation and infinite impulse response filters to the primary sensor readings in order to reduce the signal noise and improve its quality. Once the primary sensor readings are filtered, transpiration dynamics such as: transpiration, stomatal conductance, leaf-air-temperature-difference and vapor pressure deficit are calculated in real time by the smart sensor. This permits the user to observe different primary and calculated measurements at the same time and the relationship between these which is very useful in precision agriculture in the detection of abnormal conditions. Finally, transpiration related stress conditions can be detected in real time because of the use of online processing and embedded communications capabilities. PMID:22163656

  20. Hydraulic limits on maximum plant transpiration and the emergence of the safetyefficiency trade-off

    E-print Network

    Jackson, Robert B.

    Hydraulic limits on maximum plant transpiration and the emergence of the safety­efficiency trade.12126 Key words: hydraulic limitation, safety­ efficiency trade-off, soil­plant­atmosphere model, trait hydraulics constrain ecosystem productivity by setting physical limits to water transport and hence carbon

  1. Plant canopy transpiration in bioregenerative life support systems - The link between mechanistic and empirical models

    NASA Technical Reports Server (NTRS)

    Sirko, Robert J.; Mccormack, Ann C.; Edeen, Marybeth A.

    1992-01-01

    A model of water transpiration in a plant canopy that combines two approaches is presented. The first approach is to account for underlying physical processes, while the second is to empirically incorporate transpiration data now being generated at the Johnson Center Variable Pressure Growth Chamber. The two approaches, physical modeling and data analysis, make it possible to produce a model that is more robust than either the standard first-principles model or a straightforward empirical model. It is shown that the present transpiration model is able to efficiently capture the dynamic behavior of the plant canopy over the entire range of environmental parameters now envisioned to be important in an operating controlled ecological life support system (CELSS). Examples of the use of this model in assessing plant canopy dynamics and CELSS design options are also presented.

  2. Differences in transpiration rates between tropical and temperate grasses under controlled conditions

    Microsoft Academic Search

    R. W. Downes

    1969-01-01

    Two experiments were conducted to determine the transpiration rates of tropical and temperate grasses under a range of environmental conditions. In dense populations, three temperate grasses lost considerably more water per unit leaf area than did four tropical grasses, though tropical grasses tended to produce more dry matter per unit leaf area. The efficiency of production in relation to water

  3. Effect of transpiration on plant accumulation and translocation of PPCP/EDCs.

    PubMed

    Dodgen, Laurel K; Ueda, Aiko; Wu, Xiaoqin; Parker, David R; Gan, Jay

    2015-03-01

    The reuse of treated wastewater for agricultural irrigation in arid and hot climates where plant transpiration is high may affect plant accumulation of pharmaceutical and personal care products (PPCPs) and endocrine disrupting chemicals (EDCs). In this study, carrot, lettuce, and tomato plants were grown in solution containing 16 PPCP/EDCs in either a cool-humid or a warm-dry environment. Leaf bioconcentration factors (BCF) were positively correlated with transpiration for chemical groups of different ionized states (p < 0.05). However, root BCFs were correlated with transpiration only for neutral PPCP/EDCs (p < 0.05). Neutral and cationic PPCP/EDCs showed similar accumulation, while anionic PPCP/EDCs had significantly higher accumulation in roots and significantly lower accumulation in leaves (p < 0.05). Results show that plant transpiration may play a significant role in the uptake and translocation of PPCP/EDCs, which may have a pronounced effect in arid and hot climates where irrigation with treated wastewater is common. PMID:25594843

  4. The Arabidopsis outward K+ channel GORK is involved in regulation of stomatal movements and plant transpiration

    Microsoft Academic Search

    Eric Hosy; Alain Vavasseur; Karine Mouline; Ingo Dreyer; Frédéric Gaymard; Fabien Porée; Jossia Boucherez; Anne Lebaudy; David Bouchez; Anne-Aliénor Véry; Thierry Simonneau; Jean-Baptiste Thibaud; Hervé Sentenac

    2003-01-01

    Microscopic pores present in the epidermis of plant aerial organs, called stomata, allow gas exchanges between the inner photosynthetic tissue and the atmosphere. Regulation of stomatal aperture, preventing excess transpirational vapor loss, relies on turgor changes of two highly differentiated epidermal cells surrounding the pore, the guard cells. Increased guard cell turgor due to increased solute accumulation results in stomatal

  5. Use of Geostatistics and Plant Hydraulics to Explain Spatial Patterns of Transpiration Across Environmental Gradients

    NASA Astrophysics Data System (ADS)

    Ewers, B. E.; Adelman, J. D.; Mackay, D. S.; Loranty, M.; Traver, E.; Kruger, E. L.

    2005-12-01

    As direct measurements of tree transpiration via sap flux have become routine, the sample size of sap flux studies has dramatically increased. These large sample sizes now provide sufficient data for geostatistical analyses when measurement points are spatially explicit. In this study we tested whether 1) center-of-stand approaches to sap flux measurements and scaling are sufficient for characterizing stand level transpiration and 2) geostatistical techniques provide the information necessary for quantifying important stand and landscape level gradients. To maximize the inferences from our tests, we compared two contrasting forests: one dominated by lodgepole pine (Pinus contorta) in Wyoming and another dominated by trembling aspen (Populus tremuloides) in Wisconsin. The forest in Wyoming is characterized by low precipitation regimes dominated by snowfall while the forest in Wisconsin is characterized by moderate precipitation throughout the growing season. Analyses of the relationship between sample size and variance indicated an inflection point of 30 point pairs but the variance continued a shallow decline even at 100 point pairs. There was also evidence of species impacts on variance of transpiration that changed with environmental conditions. We used variogram analyses to quantify the spatial range of transpiration and found a variable spatial range across days with mean of approximately 30 m. The variability in spatial range could be partially explained by tree species' responses to soil moisture, vapor pressure deficit, and light based on current plant hydraulic knowledge. Our results confirm the utility of geostatistical techniques for quantifying and explaining transpiration in time and space.

  6. Improved thermal method of continual recording the transpiration flow rate dynamics

    Microsoft Academic Search

    J. Ktj?era; J. ?ermák; M. Penka

    1977-01-01

    The analysis of the dynamic properties of thermal methods of transpiration flow measurement was performed and the measuring\\u000a system developed, capable of quantitative measurements of fast flow changes (in minutes). The system is specified with a constant\\u000a automatically maintained temperature difference between the heated and reference points in the measured part of the plant.\\u000a System’s output signal related to measured

  7. A Laboratory Exercise to Assess Transpiration.

    ERIC Educational Resources Information Center

    Schrock, Gould F.

    1982-01-01

    Procedures are outlined for a laboratory exercise in which students use a gravimetric method to determine the rate of transpiration in sunflower seedlings. Discusses the data in terms of the effectiveness of stomatal openings, mechanisms for water movement in plants, and the role of transpiration in the environment. (DC)

  8. Transpirational Supply and Demand: Plant, Soil, and Atmospheric Effects Evaluated by Simulation

    NASA Astrophysics Data System (ADS)

    Federer, C. Anthony

    1982-04-01

    The assumption that transpiration is the lesser of an atmospheric demand function and a water supply function was tested by simulation with Federer's (1979) soil-plant-atmosphere model. The best estimate of atmospheric demand is called unstressed transpiration, defined as the transpiration that would occur in ambient conditions if stomata were unaffected by plant-water potential. For practical purposes the Penman equation provides a good estimate of unstressed transpiration for short vegetation but not for forests. Even when atmospheric variables and the Penman estimate are held constant among forest canopies, unstressed transpiration can vary by a factor of two because of variation both in the maximum value of leaf conductance and in the ratio of canopy conductance to leaf conductance. The best water supply function incorporates depth variation of soil water potential and of root and soil properties. A more practical supply function uses the ratio of available water in the root zone, W, to maximum available water WM. The maximum available water is soil water held at potentials less than that at which the hydraulic conductivity is 2 mm/d and greater than the critical leaf water potential at which stomata are completely closed. Using a mature hardwood forest as a standard, various parameters were varied to examine their effects on a water supply function defined as a supply constant times W/WM. The supply constant was found to be independent of soil texture and physical properties. Root density and the internal resistance of the plant to water flow were the most important determinants of the supply constant. Reasonable variation of root density and internal resistance produced variation in the constant from 1.9 mm/h, which implies that supply is less than demand only when soil is very dry, to 0.5 mm/hr, which implies that supply cannot meet the demand even when the soil is wet.

  9. Physiological action of smog on plants. I. Initial growth and transpiration studies

    Microsoft Academic Search

    H. G. Koritz; F. W. Went

    1953-01-01

    The effect of synthetic smog (1-n-hexene plus ozone) on growth and transpiration of tomato plants (Lycopersicon esculentum) and on elongation of etiolated pea sections (Pisum sativum) has been studied. Use has been made of hidden damage (growth decrease in the absence of visible injury) to measure the effect of light, sucrose spray, ..beta..-naphthoxyacetic acid, and water supply on smog injury.

  10. From evaporating pans to transpiring plants (John Dalton Medal Lecture)

    NASA Astrophysics Data System (ADS)

    Roderick, Michael

    2013-04-01

    The name of the original inventor of irrigated agriculture is lost to antiquity. Nevertheless, one can perhaps imagine an inquisitive desert inhabitant noting the greener vegetation along a watercourse and putting two and two together. Once water was being supplied and food was being produced it would be natural to ask a further question: how much water can we put on? No doubt much experience was gained down through the ages, but again, one can readily imagine someone inverting a rain gauge, filling it with water and measuring how fast the water evaporated. The inverted rain gauge measures the demand for water by the atmosphere. We call it the evaporative demand. I do not know if this is what actually happened but it sure makes an interesting start to a talk. Evaporation pans are basically inverted rain gauges. The rain gauge and evaporation pan measure the supply and demand respectively and these instruments are the workhorses of agricultural meteorology. Rain gauges are well known. Evaporation pans are lesser known but are in widespread use and are a key part of several national standardized meteorological networks. Many more pans are used for things like scheduling irrigation on farms or estimating evaporation from lakes. Analysis of the long records now available from standardized networks has revealed an interesting phenomenon, i.e., pan evaporation has increased in some places and decreased in other but when averaged over large numbers of pans there has been a steady decline. These independent reports from, for example, the US, Russia, China, India, Thailand, are replicated in the southern hemisphere in, for example, Australia, New Zealand and South Africa. One often hears the statement that because the earth is expected to warm with increasing greenhouse gas emissions then it follows that water will evaporate faster. The pan evaporation observations show that this widely held expectation is wrong. When expectations disagree with observations, it is the observations that win. That is the basis of science. In this Dalton Medal lecture we first examine pan evaporation observations and show why pan evaporation has declined. Armed with that knowledge we then investigate the consequences for plant water use and how this is directly coupled to the catchment water balance.

  11. (Presentation in English) AtGTL1 regulates transpiration and water-use efficiency by controlling

    E-print Network

    Ejiri, Shinji

    (Presentation in English) AtGTL1 regulates transpiration and water-use efficiency by controlling regulator of WUE by controlling stomatal density and, in turn, transpiration through transrepression of SDD1 plants had lower light-period but not dark-period transpiration rates, without a concomitant reduction

  12. Absence of Hg transpiration by shoot after Hg uptake by roots of six terrestrial plant species.

    PubMed

    Greger, Maria; Wang, Yaodong; Neuschütz, Clara

    2005-03-01

    In this paper we investigated if, and to what extent, six different plant species accumulate, translocate and emit mercury (Hg) into the air. The Hg uptake by roots, distribution of Hg to the shoot and release of Hg via shoots of garden pea, spring wheat, sugar beet, oil-seed rape, white clover and willow were investigated in a transpiration chamber. The airborne Hg was trapped in a Hopcalite trap or a gold trap. Traps and plant materials were analysed for content of Hg by CVAAS. The results show that all plant species were able to take up Hg to a large extent from a nutrient solution containing 200 microg L(-1) Hg. However, the Hg translocation to the shoot was low (0.17-2.5%) and the Hg that reached the leaves was trapped and no release of the absorbed Hg to the air was detected. PMID:15589647

  13. The Arabidopsis outward K+ channel GORK is involved in regulation of stomatal movements and plant transpiration.

    PubMed

    Hosy, Eric; Vavasseur, Alain; Mouline, Karine; Dreyer, Ingo; Gaymard, Frédéric; Porée, Fabien; Boucherez, Jossia; Lebaudy, Anne; Bouchez, David; Very, Anne-Aliénor; Simonneau, Thierry; Thibaud, Jean-Baptiste; Sentenac, Hervé

    2003-04-29

    Microscopic pores present in the epidermis of plant aerial organs, called stomata, allow gas exchanges between the inner photosynthetic tissue and the atmosphere. Regulation of stomatal aperture, preventing excess transpirational vapor loss, relies on turgor changes of two highly differentiated epidermal cells surrounding the pore, the guard cells. Increased guard cell turgor due to increased solute accumulation results in stomatal opening, whereas decreased guard cell turgor due to decreased solute accumulation results in stomatal closing. Here we provide direct evidence, based on reverse genetics approaches, that the Arabidopsis GORK Shaker gene encodes the major voltage-gated outwardly rectifying K(+) channel of the guard cell membrane. Expression of GORK dominant negative mutant polypeptides in transgenic Arabidopsis was found to strongly reduce outwardly rectifying K(+) channel activity in the guard cell membrane, and disruption of the GORK gene (T-DNA insertion knockout mutant) fully suppressed this activity. Bioassays on epidermal peels revealed that disruption of GORK activity resulted in impaired stomatal closure in response to darkness or the stress hormone abscisic acid [corrected]. Transpiration measurements on excised rosettes and intact plants (grown in hydroponic conditions or submitted to water stress) revealed that absence of GORK activity resulted in increased water consumption. The whole set of data indicates that GORK is likely to play a crucial role in adaptation to drought in fluctuating environments. PMID:12671068

  14. The Arabidopsis outward K+ channel GORK is involved in regulation of stomatal movements and plant transpiration

    PubMed Central

    Hosy, Eric; Vavasseur, Alain; Mouline, Karine; Dreyer, Ingo; Gaymard, Frédéric; Porée, Fabien; Boucherez, Jossia; Lebaudy, Anne; Bouchez, David; Véry, Anne-Aliénor; Simonneau, Thierry; Thibaud, Jean-Baptiste; Sentenac, Hervé

    2003-01-01

    Microscopic pores present in the epidermis of plant aerial organs, called stomata, allow gas exchanges between the inner photosynthetic tissue and the atmosphere. Regulation of stomatal aperture, preventing excess transpirational vapor loss, relies on turgor changes of two highly differentiated epidermal cells surrounding the pore, the guard cells. Increased guard cell turgor due to increased solute accumulation results in stomatal opening, whereas decreased guard cell turgor due to decreased solute accumulation results in stomatal closing. Here we provide direct evidence, based on reverse genetics approaches, that the Arabidopsis GORK Shaker gene encodes the major voltage-gated outwardly rectifying K+ channel of the guard cell membrane. Expression of GORK dominant negative mutant polypeptides in transgenic Arabidopsis was found to strongly reduce outwardly rectifying K+ channel activity in the guard cell membrane, and disruption of the GORK gene (T-DNA insertion knockout mutant) fully suppressed this activity. Bioassays on epidermal peels revealed that disruption of GORK activity resulted in impaired stomatal closure in response to darkness or the stress hormone azobenzenearsonate. Transpiration measurements on excised rosettes and intact plants (grown in hydroponic conditions or submitted to water stress) revealed that absence of GORK activity resulted in increased water consumption. The whole set of data indicates that GORK is likely to play a crucial role in adaptation to drought in fluctuating environments. PMID:12671068

  15. Validation of canopy transpiration in a mixed-species foothill eucalypt forest using a soil-plant-atmosphere model

    NASA Astrophysics Data System (ADS)

    Gharun, Mana; Turnbull, Tarryn L.; Adams, Mark A.

    2013-06-01

    Studies of the hydrology of native eucalypt forests in south-east Australia have focused on ash-type eucalypt species that are largely confined to Victoria and Tasmania. Mixed species foothill forests comprise the largest proportion of the forest estate in south-east Australia, yet are poorly known hydrologically. The ability to predict forest transpiration, both with reasonable accuracy and in response to changes in the environment, is essential for catchment management. A soil-plant-atmosphere model (SPA) was validated for 222 days in a mature, mixed species forest of north-east Victoria using measurements of overstorey transpiration (Eucalyptus radiata and Eucalyptus goniocalyx) and site-specific climate and vegetation parameters. There was a stronger relationship between average daily transpiration (0.71 mm day-1) and daily minimum relative humidity (R2 = 0.71), than between average daily transpiration and daily maximum temperature (R2 = 0.65). Stand water use could be predicted best from vapour pressure deficit (R2 = 0.89). SPA successfully predicted stand transpiration (R2 = 0.85) over a range of soil water and climatic conditions. A sensitivity analysis suggests that among the various required inputs, leaf area index (LAI) was the most important, and accurate estimates of LAI could significantly improve estimation of stand transpiration.

  16. Overexpression of rice NAC gene SNAC1 improves drought and salt tolerance by enhancing root development and reducing transpiration rate in transgenic cotton.

    PubMed

    Liu, Guanze; Li, Xuelin; Jin, Shuangxia; Liu, Xuyan; Zhu, Longfu; Nie, Yichun; Zhang, Xianlong

    2014-01-01

    The SNAC1 gene belongs to the stress-related NAC superfamily of transcription factors. It was identified from rice and overexpressed in cotton cultivar YZ1 by Agrobacterium tumefaciens-mediated transformation. SNAC1-overexpressing cotton plants showed more vigorous growth, especially in terms of root development, than the wild-type plants in the presence of 250 mM NaCl under hydroponic growth conditions. The content of proline was enhanced but the MDA content was decreased in the transgenic cotton seedlings under drought and salt treatments compared to the wild-type. Furthermore, SNAC1-overexpressing cotton plants also displayed significantly improved tolerance to both drought and salt stresses in the greenhouse. The performances of the SNAC1-overexpressing lines under drought and salt stress were significantly better than those of the wild-type in terms of the boll number. During the drought and salt treatments, the transpiration rate of transgenic plants significantly decreased in comparison to the wild-type, but the photosynthesis rate maintained the same at the flowering stage in the transgenic plants. These results suggested that overexpression of SNAC1 improve more tolerance to drought and salt in cotton through enhanced root development and reduced transpiration rates. PMID:24489802

  17. Cadmium exposure in Brassica juncea causes a decline in transpiration rate and leaf expansion without effect on photosynthesis

    Microsoft Academic Search

    Angela Haag-Kerwer; Holger J. Schafer; Senta Heiss; Cornelia Walter; Thomas Rausch

    1999-01-01

    decline in transpiration rate. Brassica juncea L. is able to accumulate more than Key words: Brassica juncea, gas exchange, chlorophyll 400 m gg '1 DW Cd in the shoot, a physiological trait fluorescence, growth, phytochelatin, c-ECS, MT2, which may be exploited for the bioremediation of cadmium.

  18. Transpiration cooling of hypersonic blunt bodies with finite rate surface reactions

    NASA Technical Reports Server (NTRS)

    Henline, William D.

    1989-01-01

    The convective heat flux blockage to blunt body and hypersonic vehicles by transpiration cooling are presented. The general problem of mass addition to laminar boundary layers is reviewed. Results of similarity analysis of the boundary layer problem are provided for surface heat flux with transpiration cooling. Detailed non-similar results are presented from the numerical program, BLIMPK. Comparisons are made with the similarity theory. The effects of surface catalysis are investigated.

  19. Isotopic composition of transpiration and rates of change in leaf water isotopologue storage in response to environmental variables.

    PubMed

    Simonin, Kevin A; Roddy, Adam B; Link, Percy; Apodaca, Randy; Tu, Kevin P; Hu, Jia; Dawson, Todd E; Barbour, Margaret M

    2013-12-01

    During daylight hours, the isotope composition of leaf water generally approximates steady-state leaf water isotope enrichment model predictions. However, until very recently there was little direct confirmation that isotopic steady-state (ISS) transpiration in fact exists. Using isotope ratio infrared spectroscopy (IRIS) and leaf gas exchange systems we evaluated the isotope composition of transpiration and the rate of change in leaf water isotopologue storage (isostorage) when leaves were exposed to variable environments. In doing so, we developed a method for controlling the absolute humidity entering the gas exchange cuvette for a wide range of concentrations without changing the isotope composition of water vapour. The measurement system allowed estimation of (18)O enrichment both at the evaporation site and for bulk leaf water, in the steady state and the non-steady state. We show that non-steady-state effects dominate the transpiration isoflux even when leaves are at physiological steady state. Our results suggest that a variable environment likely prevents ISS transpiration from being achieved and that this effect may be exacerbated by lengthy leaf water turnover times due to high leaf water contents. PMID:23647101

  20. TRANSPIRATION EFFECT ON THE UPTAKE AND DISTRIBUTION OF BROMACIL, NITROBENZENE, AND PHENOL IN SOYBEAN PLANTS (JOURNAL VERSION)

    EPA Science Inventory

    The influence of transpiration rate on the uptake and translocation of two industrial waste compounds, phenol and nitrobenzene, and one pesticide, 5-bromo-3-sec-butyl-6-methyluracil (bromacil), was examined. Carbon-14 moieties of each compound were provided separately in hydropon...

  1. The effect of heavy metals on plants II. Net photosynthesis and transpiration of whole corn and sunflower plants treated with Pb, Cd, Ni, and Tl

    Microsoft Academic Search

    R. W. Carlson; F. A. Bazzaz; G. L. Rolfe

    1975-01-01

    Corn and sunflower plants were grown in hydroponic culture and treated with various levels of Pb, Cd, Ni, and Tl salts. Net photosynthesis, transpiration and toxic metal ion concentration of leaf material and total plant biomass was measured. Tl was found to be the most toxic to new photosynthesis and growth of both species followed in order by Cd, Ni,

  2. Combining quantitative trait loci analysis with physiological models to predict genotype-specific transpiration rates.

    PubMed

    Reuning, Gretchen A; Bauerle, William L; Mullen, Jack L; McKay, John K

    2015-04-01

    Transpiration is controlled by evaporative demand and stomatal conductance (gs ), and there can be substantial genetic variation in gs . A key parameter in empirical models of transpiration is minimum stomatal conductance (g0 ), a trait that can be measured and has a large effect on gs and transpiration. In Arabidopsis thaliana, g0 exhibits both environmental and genetic variation, and quantitative trait loci (QTL) have been mapped. We used this information to create a genetically parameterized empirical model to predict transpiration of genotypes. For the parental lines, this worked well. However, in a recombinant inbred population, the predictions proved less accurate. When based only upon their genotype at a single g0 QTL, genotypes were less distinct than our model predicted. Follow-up experiments indicated that both genotype by environment interaction and a polygenic inheritance complicate the application of genetic effects into physiological models. The use of ecophysiological or 'crop' models for predicting transpiration of novel genetic lines will benefit from incorporating further knowledge of the genetic control and degree of independence of core traits/parameters underlying gs variation. PMID:25124388

  3. On the enrichment of H 2 18 O in the leaves of transpiring plants

    Microsoft Academic Search

    G. Dongmann; H. W. Nuernberg; H. Foerstel; K. Wagener

    1974-01-01

    Summary The vapor pressure difference between H218O and H216O is the reason for the accumulation of the heavy molecule in transpiring leaves. Since photosynthesis on land is the main source of atmospheric oxygen, this mechanism is important for the remarkable enrichment of18O in atmospheric O2 (Dole effect). Using a simple box model for transpiring leaves a quantitative understanding of the

  4. Transpiration cooling in hypersonic flight

    NASA Technical Reports Server (NTRS)

    Tavella, Domingo; Roberts, Leonard

    1989-01-01

    A preliminary numerical study of transpiration cooling applied to a hypersonic configuration is presented. Air transpiration is applied to the NASA all-body configuration flying at an altitude of 30500 m with a Mach number of 10.3. It was found that the amount of heat disposal by convection is determined primarily by the local geometry of the aircraft for moderate rates of transpiration. This property implies that different areas of the aircraft where transpiration occurs interact weakly with each other. A methodology for quick assessments of the transpiration requirements for a given flight configuration is presented.

  5. Simulating canopy transpiration and photosynthesis of corn plants under contrasting water regimes using a coupled model

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A process-based corn simulation model (MaizeSim) was coupled with a two-dimensional soil simulator (2DSOIL) to simulate the transpiration and photosynthesis of corn under drought stress. To simulate stomatal reaction to drought stress, two stomatal controlling algorithms (control by hydraulic signal...

  6. Use of Geostatistics and Plant Hydraulics to Explain Spatial Patterns of Transpiration Across Environmental Gradients

    Microsoft Academic Search

    B. E. Ewers; J. D. Adelman; D. S. Mackay; M. Loranty; E. Traver; E. L. Kruger

    2005-01-01

    As direct measurements of tree transpiration via sap flux have become routine, the sample size of sap flux studies has dramatically increased. These large sample sizes now provide sufficient data for geostatistical analyses when measurement points are spatially explicit. In this study we tested whether 1) center-of-stand approaches to sap flux measurements and scaling are sufficient for characterizing stand level

  7. Photosynthesis and Transpiration

    NSDL National Science Digital Library

    American Chemical Society

    2010-01-01

    In this activity on page 7 of the PDF, learners examine the effects that light and air have on green plants. Learners plant seeds in two containers and compare what happens when the containers are placed in dark and light places. Use this activity to introduce learners to photosynthesis and transpiration.

  8. The significance of water co-transport for sustaining transpirational water flow in plants: a quantitative approach.

    PubMed

    Fricke, Wieland

    2015-02-01

    In a recent Opinion paper, Wegner (Journal of Experimental Botany 65, 381-392, 2014) adapts a concept developed for water flow in animal tissues to propose a model, which can explain the loading of water into the root xylem against a difference in water potential (?) between the xylem parenchyma cell (more negative ?) and the xylem vessel (less negative ?). In this model, the transport of water is energized through the co-transport of ions such as K(+) and Cl(-) through plasma membrane-located transporters. The emphasis of the model is on the thermodynamic feasibility of the co-transport mechanism per se. However, what is lacking is a quantitative evaluation of the energy input required at the organismal level to sustain such a co-transport mechanism in the face of considerable net (transpirational) flows of water through the system. Here, we use a ratio of 500 water molecules being co-transported for every pair of K(+) and Cl(-) ions, as proposed for the animal system, to calculate the energy required to sustain daytime and night-time transpirational water flow in barley plants through a water co-transport mechanism. We compare this energy with the total daily net input of energy through photosynthetic carbon assimilation. Water co-transport can facilitate the filling of xylem against a difference in ? of 1.0MPa and puts a minor drain on the energy budget of the plant. Based on these findings it cannot be excluded that water co-transport in plants contributes significantly to xylem filling during night-time and possibly also daytime transpiration. PMID:25563967

  9. Thermophoretically enhanced mass transport rates to solid and transpiration-cooled walls across turbulent (law-of-the-wall) boundary layers

    NASA Technical Reports Server (NTRS)

    Gokoglu, Suleyman A.; Rosner, Daniel E.

    1985-01-01

    Convective-diffusion mass transfer rate predictions are made for both solid wall and transpiration-cooled 'law-of-the-wall' nonisothermal turbulent boundary layers (TBLs), including the mechanism of thermophoresis, i.e., small particle mass transport 'down a temperature gradient'. The present calculations are confined to low mass-loading situations but span the entire particle size range from vapor molecules to particles near the onset of inertial ('eddy') impaction. It is shown that, when Sc is much greater than 1, thermophoresis greatly increases particle deposition rates to internally cooled solid walls, but only partially offsets the appreciable reduction in deposition rates associated with dust-free gas-transpiration-cooled surfaces. Thus, efficient particle sampling from hot dusty gases can be carried out using transpiration 'shielded' probe surfaces.

  10. Sap flow measurements to determine the transpiration of facade greenings

    NASA Astrophysics Data System (ADS)

    Hölscher, Marie-Therese; Nehls, Thomas; Wessolek, Gerd

    2014-05-01

    Facade greening is expected to make a major contribution to the mitigation of the urban heat-island effect through transpiration cooling, thermal insulation and shading of vertical built structures. However, no studies are available on water demand and the transpiration of urban vertical green. Such knowledge is needed as the plants must be sufficiently watered, otherwise the posited positive effects of vertical green can turn into disadvantages when compared to a white wall. Within the framework of the German Research Group DFG FOR 1736 "Urban Climate and Heat Stress" this study aims to test the practicability of the sap flow technique for transpiration measurements of climbing plants and to obtain potential transpiration rates for the most commonly used species. Using sap flow measurements we determined the transpiration of Fallopia baldschuanica, Parthenocissus tricuspidata and Hedera helix in pot experiments (about 1 m high) during the hot summer period from August 17th to August 30th 2012 under indoor conditions. Sap flow measurements corresponded well to simultaneous weight measurement on a daily base (factor 1.19). Fallopia baldschuanica has the highest daily transpiration rate based on leaf area (1.6 mm d-1) and per base area (5.0 mm d-1). Parthenocissus tricuspidata and Hedera helix show transpiration rates of 3.5 and 0.4 mm d-1 (per base area). Through water shortage, transpiration strongly decreased and leaf temperature measured by infrared thermography increased by 1 K compared to a well watered plant. We transferred the technique to outdoor conditions and will present first results for facade greenings in the inner-city of Berlin for the hottest period in summer 2013.

  11. Genetic variation in a grapevine progeny (Vitis vinifera L. cvs Grenache×Syrah) reveals inconsistencies between maintenance of daytime leaf water potential and response of transpiration rate under drought

    PubMed Central

    Coupel-Ledru, Aude; Lebon, Éric; Christophe, Angélique; Doligez, Agnès; Cabrera-Bosquet, Llorenç; Péchier, Philippe; Hamard, Philippe; This, Patrice; Simonneau, Thierry

    2014-01-01

    In the face of water stress, plants evolved with different abilities to limit the decrease in leaf water potential, notably in the daytime (?M). So-called isohydric species efficiently maintain high ?M, whereas anisohydric species cannot prevent ?M from dropping as soil water deficit develops. The genetic and physiological origins of these differences in (an)isohydric behaviours remain to be clarified. This is of particular interest within species such as Vitis vinifera L. where continuous variation in the level of isohydry has been observed among cultivars. With this objective, a 2 year experiment was conducted on the pseudo-F1 progeny from a cross between the two widespread cultivars Syrah and Grenache using a phenotyping platform coupled to a controlled-environment chamber. Potted plants of all the progeny were analysed for ?M, transpiration rate, and soil-to-leaf hydraulic conductance, under both well-watered and water deficit conditions. A high genetic variability was found for all the above traits. Four quantitative trait loci (QTLs) were detected for ?M under water deficit conditions, and 28 other QTLs were detected for the different traits in either condition. Genetic variation in ?M maintenance under water deficit weakly correlated with drought-induced reduction in transpiration rate in the progeny, and QTLs for both traits did not completely co-localize. This indicates that genetic variation in the control of ?M under water deficit was not due simply to variation in transpiration sensitivity to soil drying. Possible origins of the diversity in (an)isohydric behaviours in grapevine are discussed on the basis of concurrent variations in soil-to-leaf hydraulic conductance and stomatal control of transpiration. PMID:25381432

  12. Vapour pressure deficit during growth has little impact on genotypic differences of transpiration efficiency at leaf and whole-plant level: an example from Populus nigra?L.

    PubMed

    Rasheed, Fahad; Dreyer, Erwin; Richard, Béatrice; Brignolas, Franck; Brendel, Oliver; LE Thiec, Didier

    2015-04-01

    Poplar genotypes differ in transpiration efficiency (TE) at leaf and whole-plant level under similar conditions. We tested whether atmospheric vapour pressure deficit (VPD) affected TE to the same extent across genotypes. Six Populus nigra genotypes were grown under two VPD. We recorded (1) (13) C content in soluble sugars; (2) (18) O enrichment in leaf water; (3) leaf-level gas exchange; and (4) whole-plant biomass accumulation and water use. Whole-plant and intrinsic leaf TE and (13) C content in soluble sugars differed significantly among genotypes. Stomatal conductance contributed more to these differences than net CO2 assimilation rate. VPD increased water use and reduced whole-plant TE. It increased intrinsic leaf-level TE due to a decline in stomatal conductance. It also promoted higher (18) O enrichment in leaf water. VPD had no genotype-specific effect. We detected a deviation in the relationship between (13) C in leaf sugars and (13) C predicted from gas exchange and the standard discrimination model. This may be partly due to genotypic differences in mesophyll conductance, and to its lack of sensitivity to VPD. Leaf-level (13) C discrimination was a powerful predictor of the genetic variability of whole-plant TE irrespective of VPD during growth. PMID:25099629

  13. Climate change at northern latitudes: rising atmospheric humidity decreases transpiration, N-uptake and growth rate of hybrid aspen.

    PubMed

    Tullus, Arvo; Kupper, Priit; Sellin, Arne; Parts, Leopold; Sõber, Jaak; Tullus, Tea; Lõhmus, Krista; Sõber, Anu; Tullus, Hardi

    2012-01-01

    At northern latitudes a rise in atmospheric humidity and precipitation is predicted as a consequence of global climate change. We studied several growth and functional traits of hybrid aspen (Populus tremula L.×P. tremuloides Michx.) in response to elevated atmospheric humidity (on average 7% over the ambient level) in a free air experimental facility during three growing seasons (2008-2010) in Estonia, which represents northern temperate climate (boreo-nemoral zone). Data were collected from three humidified (H) and three control (C) plots, and analysed using nested linear models. Elevated air humidity significantly reduced height, stem diameter and stem volume increments and transpiration of the trees whereas these effects remained highly significant also after considering the side effects from soil-related confounders within the 2.7 ha study area. Tree leaves were smaller, lighter and had lower leaf mass per area (LMA) in H plots. The magnitude and significance of the humidity treatment effect--inhibition of above-ground growth rate--was more pronounced in larger trees. The lower growth rate in the humidified plots can be partly explained by a decrease in transpiration-driven mass flow of NO(3) (-) in soil, resulting in a significant reduction in the measured uptake of N to foliage in the H plots. The results suggest that the potential growth improvement of fast-growing trees like aspens, due to increasing temperature and atmospheric CO(2) concentration, might be smaller than expected at high latitudes if a rise in atmospheric humidity simultaneously takes place. PMID:22880067

  14. Climate Change at Northern Latitudes: Rising Atmospheric Humidity Decreases Transpiration, N-Uptake and Growth Rate of Hybrid Aspen

    PubMed Central

    Tullus, Arvo; Kupper, Priit; Sellin, Arne; Parts, Leopold; Sõber, Jaak; Tullus, Tea; Lõhmus, Krista; Sõber, Anu; Tullus, Hardi

    2012-01-01

    At northern latitudes a rise in atmospheric humidity and precipitation is predicted as a consequence of global climate change. We studied several growth and functional traits of hybrid aspen (Populus tremula L.×P. tremuloides Michx.) in response to elevated atmospheric humidity (on average 7% over the ambient level) in a free air experimental facility during three growing seasons (2008–2010) in Estonia, which represents northern temperate climate (boreo-nemoral zone). Data were collected from three humidified (H) and three control (C) plots, and analysed using nested linear models. Elevated air humidity significantly reduced height, stem diameter and stem volume increments and transpiration of the trees whereas these effects remained highly significant also after considering the side effects from soil-related confounders within the 2.7 ha study area. Tree leaves were smaller, lighter and had lower leaf mass per area (LMA) in H plots. The magnitude and significance of the humidity treatment effect – inhibition of above-ground growth rate – was more pronounced in larger trees. The lower growth rate in the humidified plots can be partly explained by a decrease in transpiration-driven mass flow of NO3? in soil, resulting in a significant reduction in the measured uptake of N to foliage in the H plots. The results suggest that the potential growth improvement of fast-growing trees like aspens, due to increasing temperature and atmospheric CO2 concentration, might be smaller than expected at high latitudes if a rise in atmospheric humidity simultaneously takes place. PMID:22880067

  15. Impacts of forest thinning and climate change on transpiration and runoff rates in Sierra Nevada mixed-conifer headwater catchments

    NASA Astrophysics Data System (ADS)

    Saksa, P. C.; Ray, R. L.; Bales, R. C.; Conklin, M. H.

    2013-12-01

    Using a spatially explicit hydro-ecological model, impacts from forest thinning and climate change on snowpack, evapotranspiration (ET) rates, soil moisture storage, and runoff were investigated in Sierra Nevada headwater catchments spanning elevations of 1,500 to 2,000-m. Along this elevation gradient, precipitation changes from rain-dominated to snow-dominated, so precipitation phase will be strongly impacted by increases in temperature. Mixed-conifer forests in the Sierra Nevada near the 2,000-m elevation band also transpire at a high rate relative to upper elevation forests that are more restricted by colder winter temperatures and lower elevation forests that are more restricted by lower summer soil moisture, increasing the potential of reduced transpiration with vegetation thinning. Forest treatment and climate change scenarios were modeled using the Regional Hydro-Ecological Simulation System (RHESSys), calibrated with two years of snow, soil moisture, and streamflow observations. Simulations of forest thinning at moderate (66% of current vegetation density) and restoration (33% density) levels were combined with precipitation changes up to 20% and temperature increases up to 6?C for projecting impacts on ET and runoff rates. Model results indicated that moderate thinning alone could increase runoff by 3%, but additional temperature increases of 2-4?C could increase runoff rates another 6% - similar to a restoration level thinning. Modifying temperature and precipitation separately showed that the two methods of climate forcing both led to fluctuations in soil moisture, caused by changes in precipitation phase (snow/rain) and final day of snowpack melt. The snowmelt timing affected runoff rates by causing changes in the spring soil moisture recession, and showed that it may be one of the critical processes that affects annual runoff rates, not just runoff timing. Simulations of precipitation and temperature changes together showed that precipitation would be the main driver of runoff change in the current vegetation and restoration thinning scenarios, while both precipitation and temperature would drive runoff rates in a moderate thinning scenario. Ultimately, the forest thinning scenarios directly led to decreases in evapotranspiration and increases in runoff as expected, with a warmer climate potentially enhancing these changes.

  16. Latent manganese deficiency increases transpiration in barley (Hordeum vulgare).

    PubMed

    Hebbern, Christopher A; Laursen, Kristian Holst; Ladegaard, Anne H; Schmidt, Sidsel B; Pedas, Pai; Bruhn, Dan; Schjoerring, Jan K; Wulfsohn, Dvoralai; Husted, Søren

    2009-03-01

    To investigate if latent manganese (Mn) deficiency leads to increased transpiration, barley plants were grown for 10 weeks in hydroponics with daily additions of Mn in the low nM range. The Mn-starved plants did not exhibit visual leaf symptoms of Mn deficiency, but Chl a fluorescence measurements revealed that the quantum yield efficiency of PSII (F(v)/F(m)) was reduced from 0.83 in Mn-sufficient control plants to below 0.5 in Mn-starved plants. Leaf Mn concentrations declined from 30 to 7 microg Mn g(-1) dry weight in control and Mn-starved plants, respectively. Mn-starved plants had up to four-fold higher transpiration than control plants. Stomatal closure and opening upon light/dark transitions took place at the same rate in both Mn treatments, but the nocturnal leaf conductance for water vapour was still twice as high in Mn-starved plants compared with the control. The observed increase in transpiration was substantiated by (13)C-isotope discrimination analysis and gravimetric measurement of the water consumption, showing significantly lower water use efficiency in Mn-starved plants. The extractable wax content of leaves of Mn-starved plants was approximately 40% lower than that in control plants, and it is concluded that the increased leaf conductance and higher transpirational water loss are correlated with a reduction in the epicuticular wax layer under Mn deficiency. PMID:19140891

  17. Determining the Transpiration Rate of Peach Trees Under Two Trickle Irrigation Regimes

    E-print Network

    Howell, T. A.; McFarland, M. J.; Reddell, D. L.; Brown, K. W.; Newton, R. J.; Rodriguez, P. B.; Van Bavel, C. H. M.; Reeder, E. L.

    Central Texas. Initial data relating trickle irrigation amounts to total production, peach size, and plant growth have indicated that trickle irrigation may provide benefits that would offset costs of the irrigation system and water. Previous work however...

  18. Solute Export Through Transpiration: A Possible Control of Soil Water Chemistry?

    NASA Astrophysics Data System (ADS)

    Alexander, S. C.; Boyle, D. B.; Alexander, E. C.

    2005-12-01

    Recent studies of soil and ground water interactions in western Minnesota have produced seemingly anomalous results. The soil waters beneath highly transpirative plants (Typha sp., Salix sp. and Populus sp.) in a ground water discharge area developed high calcium sulfate concentrations with only minor enrichment of sodium and chloride. It was expected that concentration of solutes by evapo-transpiration would enrich all ions in the originating ground water more equally. Transpired water is generally assumed to be essentially distilled water although there is little analytical data to support this hypothesis. Given the very high evapotranspiration rates of Western Minnesota, greater than 95% of total water movement, even relatively dilute ion concentrations in the transpired water may be significant in the total chemical budget. To investigate the chemistry of transpired water we adapted techniques that have been used to study total transpiration rates as well as isotopic composition of transpired waters. Our initial results from typha sp. have produced waters that while relatively dilute are distinctly not distilled water. Control samples using de-ionized water over dead vegetation produced minor ion enrichment. All results are in ppm. Ion - Ca, Mg, Na, K, P, Mn, Cl , SO4, NO3-N soil water - 18.5, 2.9, 4.8, 3.8, 0.2, 0.2, 5.6, 2.4, 0.5 transpiration - 1.9, 0.6, 1.5, 8.5, 0.3, 0.4, 9.0, 1.6, <0.1 DI control - 0.1, <0.1, 0.1, <0.1, <0.1, <0.1, <0.1, 1.6, <0.1 The observed transpiration chemistries are in rough agreement with reported literature values for plant stem water. While many plants are known to excrete large molecules the expulsion of ions in transpired water would represent a novel chemical plant pathway.

  19. The isotopic signature of transpiration in mixed conifer forest

    NASA Astrophysics Data System (ADS)

    Williams, D. G.; Ewers, B.; Angstmann, J. L.; Guemouria, N.; Chehbouni, A.

    2008-12-01

    Isotopic measurements of water vapor in forest air provide insights into ecosystem level responses to variability in surface hydrology. Studies of isotopic water balance of ecosystems should account for variation in the isotopic signature of transpired vapor in the non-steady state as well as isotopic differences in source water among dominant forest plants. Generally low rates of leaf gas exchange in some tree species, especially conifers, are associated with low leaf-water turnover rates, which greatly extends the time required to achieve transpiration at isotopic steady state as environmental conditions change over diurnal periods. Leaf longevity is also quite high (ca. 6-10 yrs.) in many evergreen coniferous species and stomatal conductance and rates of leaf gas exchange tend to decline as leaves age in conifer stands. We measured hydrogen and oxygen stable isotope ratios of water in leaves of different ages and from different canopy positions in sub-alpine fir (Abies lasiocarpa) and Engelmann spruce (Picea englemannii) over two separate diurnal periods during the growing season of 2008 in high elevation, mixed coniferous forest in the Snowy Range of southeastern Wyoming, USA. We collected needles every 3-4 h over 24-h periods to investigate the dynamics leaf water isotopic enrichment. Concurrent measurements of leaf gas exchange and leaf water content allowed us to model the leaf water turnover rate and the isotope ratio of transpiration in the non-steady state. Daily patterns of transpiration determined from sapflux measurements agreed with patterns of leaf conductance and transpiration determined from leaf-level by gas exchange measurements. Afternoon stomatal closure reduced leaf and tree level transpiration and leaf water turnover rates. Atmospheric water vapor was collected also every 3-4 h for isotopic analysis at multiple heights within and above the canopy. The isotopic composition of water vapor in the forest canopy became enriched in the heavy isotopes of hydrogen and oxygen during midday periods relative to that during early morning and nighttime periods reflecting an increased contribution of transpired water vapor to canopy air at midday. Keeling plot analyses suggested that the isotopic composition of the evapotranspiration flux was not constant during daytime periods, potentially reflecting changes in the isotope ratio of forest transpiration associated with transpiration at isotopic non-steady state. We conclude that modeling the isotope composition of forest transpiration should take into account the variation in leaf water turnover rates associated with leaf age and canopy position.

  20. Estimating High Rates of Transpiration in Woody Vines with the Heat-Balance Method

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Heat-balance sap flow gauges were configured to produce a more thermally uniform stem cross-section under high flow rates. On mature grapevines (Vitis labruscana) either undisturbed in the field or transplanted to large containers (ca. 1m^3 volume), with stem diameters up to 46 mm and leaf area per ...

  1. Transpiration of urban forests in the Los Angeles metropolitan area.

    PubMed

    Pataki, Diane E; McCarthy, Heather R; Litvak, Elizaveta; Pincetl, Stephanie

    2011-04-01

    Despite its importance for urban planning, landscape management, and water management, there are very few in situ estimates of urban-forest transpiration. Because urban forests contain an unusual and diverse mix of species from many regions worldwide, we hypothesized that species composition would be a more important driver of spatial variability in urban-forest transpiration than meteorological variables in the Los Angeles (California, USA) region. We used constant-heat sap-flow sensors to monitor urban tree water use for 15 species at six locations throughout the Los Angeles metropolitan area. For many of these species no previous data on sap flux, water use, or water relations were available in the literature. To scale sap-flux measurements to whole trees we conducted a literature survey of radial trends in sap flux across multiple species and found consistent relationships for angiosperms vs. gymnosperms. We applied this relationship to our measurements and estimated whole-tree and plot-level transpiration at our sites. The results supported very large species differences in transpiration, with estimates ranging from 3.2 +/- 2.3 kg x tree(-1) x d(-1) in unirrigated Pinus canariensis (Canary Island pine) to 176.9 +/- 75.2 kg x tree(-1) x d(-1) in Platanus hybrida (London planetree) in the month of August. Other species with high daily transpiration rates included Ficus microcarpa (laurel fig), Gleditsia triacanthos (honeylocust), and Platanus racemosa (California sycamore). Despite irrigation and relatively large tree size, Brachychiton populneas (kurrajong), B. discolor (lacebark), Sequoia sempervirens (redwood), and Eucalyptus grandis (grand Eucalyptus) showed relatively low rates of transpiration, with values < 45 kg x tree(-1) x d(-1). When scaled to the plot level, transpiration rates were as high as 2 mm/d for sites that contained both species with high transpiration rates and high densities of planted trees. Because plot-level transpiration is highly dependent on tree density, we modeled transpiration as a function of both species and density to evaluate a likely range of values in irrigated urban forests. The results show that urban forests in irrigated, semi-arid regions can constitute a significant use of water, but water use can be mitigated by appropriate selection of site, management method, and species. PMID:21639035

  2. Variations in transpiration rate and leaf cell turgor maintenance in saplings of deciduous broad-leaved tree species common in cool temperate forests in Japan.

    PubMed

    Saito, Takami; Tanaka, Tadashi; Tanabe, Hiromi; Matsumoto, Yoosuke; Morikawa, Yasushi

    2003-01-01

    To clarify mechanisms underlying variation in transpiration rate among deciduous broad-leaved tree species, we measured diurnal changes in stomatal conductance (gs) and leaf water potential, and calculated the maximum transpiration rate (Emax), leaf-specific hydraulic conductance (K(s-l)) and difference between the soil water potential and the daily minimum leaf water potential (Psis - Psi(l,min)). Pressure-volume (P-V) measurements were made on leaves. Saplings of eight broad-leaved tree species that are common in Japanese cool temperate forests were studied. Maximum transpiration rate varied significantly among species. There was a statistically significant difference in Psis - Psi(l,min), but not in K(s-l). Species with large Emax also had large Psis - Psi(l,min) and gs. The results of the P-V analyses showed that species with a large Psis - Psi(l,min) maintained turgor even at low leaf water potentials. The similar daily minimum leaf pressure potentials (Psip) across all eight species indicate that Psip values below this minimum are critical. Based on these results, we suggest that the leaf cell capacity for turgor maintenance strongly affects Psis - Psi(l,min) and consequently Emax via stomatal regulation. PMID:12511305

  3. [Transpiration of Choerospondias axillaris in agro-forestrial system and its affecting factors].

    PubMed

    Zhao, Ying; Zhang, Bin; Zhao, Huachun; Wang, Mingzhu

    2005-11-01

    Measurement of transpiration is essential to assess plant water use efficiency. Applying Grainer method, this paper measured the sap flow of Choerospondias axillaries in an agro-forestrial system, aimed to evaluate the effects of intercropping and pruning on the diurnal variation of transpiration, and to relate the transpiration rate with climatic factors. The results showed that the diurnal variation of Choerospondias arillaries transpiration rate appeared in parabola, low in the morning and evening, and high at noon. The transpiration rate was closely related to leaf stomatal conductivity and soil water potential, especially the water potential in 100 cm soil depth (R = 0.737). The transpiration rate of Choerospondias axillaries was increased by about 40% approximately 160% in agro-forestrial system through the changes in regional environment and in the deep soil water use by tree. Correlation analysis and multi-factor successive regression analysis indicated that the transpiration was controlled by ray radiation intensity, air temperature and ground temperature, followed by the difference between saturated and actual vapor pressure and the wind speed. A statistical model for calculating the sap flow rate by micrometeorological factors was also provided. PMID:16471335

  4. Ecophysiology of cuticular transpiration: comparative investigation of cuticular water permeability of plant species from different habitats

    Microsoft Academic Search

    L. Schreiber; M. Riederer

    1996-01-01

    Water permeabilities of astomatous, isolated cuticular membranes (CM) of 24 different plants species were measured. Permeances varied from 1.7×10-11 m·s-1 (Vanilla planifolia leaf) up to 2.1×10-9 m·s-1 (Malus cf. domestica fruit) among different plant species, thus covering a range of over 2 orders of magnitude. Ranking of species according to permeances resulted in four distinct groups. The first group, of

  5. Where do roots take up water? Neutron radiography of water flow into the roots of transpiring plants growing in soil.

    PubMed

    Zarebanadkouki, Mohsen; Kim, Yangmin X; Carminati, Andrea

    2013-09-01

    Where and how fast does water flow from soil into roots? The answer to this question requires direct and in situ measurement of local flow of water into roots of transpiring plants growing in soil. We used neutron radiography to trace the transport of deuterated water (D?O) in lupin (Lupinus albus) roots. Lupins were grown in aluminum containers (30 × 25 × 1 cm) filled with sandy soil. D?O was injected in different soil regions and its transport in soil and roots was monitored by neutron radiography. The transport of water into roots was then quantified using a convection-diffusion model of D?O transport into roots. The results showed that water uptake was not uniform along roots. Water uptake was higher in the upper soil layers than in the lower ones. Along an individual root, the radial flux was higher in the proximal segments than in the distal segments. In lupins, most of the water uptake occurred in lateral roots. The function of the taproot was to collect water from laterals and transport it to the shoot. This function is ensured by a low radial conductivity and a high axial conductivity. Lupin root architecture seems well designed to take up water from deep soil layers. PMID:23692148

  6. Protein Domain Analysis of Genomic Sequence Data Reveals Regulation of LRR Related Domains in Plant Transpiration in Ficus

    PubMed Central

    Lang, Tiange; Yin, Kangquan; Liu, Jinyu; Cao, Kunfang; Cannon, Charles H.; Du, Fang K.

    2014-01-01

    Predicting protein domains is essential for understanding a protein’s function at the molecular level. However, up till now, there has been no direct and straightforward method for predicting protein domains in species without a reference genome sequence. In this study, we developed a functionality with a set of programs that can predict protein domains directly from genomic sequence data without a reference genome. Using whole genome sequence data, the programming functionality mainly comprised DNA assembly in combination with next-generation sequencing (NGS) assembly methods and traditional methods, peptide prediction and protein domain prediction. The proposed new functionality avoids problems associated with de novo assembly due to micro reads and small single repeats. Furthermore, we applied our functionality for the prediction of leucine rich repeat (LRR) domains in four species of Ficus with no reference genome, based on NGS genomic data. We found that the LRRNT_2 and LRR_8 domains are related to plant transpiration efficiency, as indicated by the stomata index, in the four species of Ficus. The programming functionality established in this study provides new insights for protein domain prediction, which is particularly timely in the current age of NGS data expansion. PMID:25269070

  7. Control of transpiration by radiation

    PubMed Central

    Pieruschka, Roland; Huber, Gregor; Berry, Joseph A.

    2010-01-01

    The terrestrial hydrological cycle is strongly influenced by transpiration—water loss through the stomatal pores of leaves. In this report we present studies showing that the energy content of radiation absorbed by the leaf influences stomatal control of transpiration. This observation is at odds with current concepts of how stomata sense and control transpiration, and we suggest an alternative model. Specifically, we argue that the steady-state water potential of the epidermis in the intact leaf is controlled by the difference between the radiation-controlled rate of water vapor production in the leaf interior and the rate of transpiration. Any difference between these two potentially large fluxes is made up by evaporation from (or condensation on) the epidermis, causing its water potential to pivot around this balance point. Previous work established that stomata in isolated epidermal strips respond by opening with increasing (and closing with decreasing) water potential. Thus, stomatal conductance and transpiration rate should increase when there is condensation on (and decrease when there is evaporation from) the epidermis, thus tending to maintain homeostasis of epidermal water potential. We use a model to show that such a mechanism would have control properties similar to those observed with leaves. This hypothesis provides a plausible explanation for the regulation of leaf and canopy transpiration by the radiation load and provides a unique framework for studies of the regulation of stomatal conductance by CO2 and other factors. PMID:20624981

  8. Control of transpiration by radiation.

    PubMed

    Pieruschka, Roland; Huber, Gregor; Berry, Joseph A

    2010-07-27

    The terrestrial hydrological cycle is strongly influenced by transpiration--water loss through the stomatal pores of leaves. In this report we present studies showing that the energy content of radiation absorbed by the leaf influences stomatal control of transpiration. This observation is at odds with current concepts of how stomata sense and control transpiration, and we suggest an alternative model. Specifically, we argue that the steady-state water potential of the epidermis in the intact leaf is controlled by the difference between the radiation-controlled rate of water vapor production in the leaf interior and the rate of transpiration. Any difference between these two potentially large fluxes is made up by evaporation from (or condensation on) the epidermis, causing its water potential to pivot around this balance point. Previous work established that stomata in isolated epidermal strips respond by opening with increasing (and closing with decreasing) water potential. Thus, stomatal conductance and transpiration rate should increase when there is condensation on (and decrease when there is evaporation from) the epidermis, thus tending to maintain homeostasis of epidermal water potential. We use a model to show that such a mechanism would have control properties similar to those observed with leaves. This hypothesis provides a plausible explanation for the regulation of leaf and canopy transpiration by the radiation load and provides a unique framework for studies of the regulation of stomatal conductance by CO(2) and other factors. PMID:20624981

  9. Transpiration- and growth-induced water potentials in maize

    SciTech Connect

    Westgate, M.E.; Boyer, J.S.

    1984-01-01

    Recent evidence from leaves and stems indicates that gradients in water potential (psi/sub w/) necessary for water movement through growing tissues are larger than previously assumed. Because growth is sensitive to tissue psi/sub w/ and the behavior of these gradients has not been investigated in transpiring plants, the authors examined the water status of all the growing and mature vegetative tissues of maize (Zea mays L.) during high and low rates of transpiration. The psi/sub w/ measured in the mature regions of the plant responded primarily to transpiration, while the psi/sub w/ in the growing regions was affected both by transpiration and growth. The transpiration-induced potentials of the mature tissue formed a gradient of decreasing psi/sub w/ along the transpiration stream while the growth-induced potentials formed a gradient of decreasing psi/sub w/ from the transpiration stream to the expanding cells in the growing tissue. The growth-induced gradient in psi/sub w/ within the leaf remained fairly constant as the xylem psi/sub w/ decreased during the day and was associated with a decreased osmotic potential (psi/sub s/) of the growing region (osmotic adjustment). The growth-induced gradient in psi/sub w/ was not caused by excision of the tissue because intact maize stems exhibited a similar psi/sub w/. These observations support the concept that large gradients in psi/sub w/ are required to maintain water flow to expanding cells within all the vegetative tissues and suggest that the maintenance of a favorable gradient in psi/sub w/ for cell enlargement may be an important role for osmotic adjustment. 33 references, 7 figures, 1 table.

  10. Maize transpiration in response to meteorological conditions

    NASA Astrophysics Data System (ADS)

    Klimešová, Jana; St?edová, Hana; St?eda, Tomáš

    2013-09-01

    Differences in transpiration of maize (Zea mays L.) plants in four soil moisture regimes were quantified in a pot experiment. The transpiration was measured by the "Stem Heat Balance" method. The dependence of transpiration on air temperature, air humidity, global solar radiation, soil moisture, wind speed and leaf surface temperature were quantified. Significant relationships among transpiration, global radiation and air temperature (in the first vegetation period in the drought non-stressed variant, r = 0.881**, r = 0.934**) were found. Conclusive dependence of transpiration on leaf temperature (r = 0.820**) and wind speed (r = 0.710**) was found. Transpiration was significantly influenced by soil moisture (r = 0.395**, r = 0.528**) under moderate and severe drought stress. The dependence of transpiration on meteorological factors decreased with increasing deficiency of water. Correlation between transpiration and plant dry matter weight (r = 0.997**), plant height (r = 0.973**) and weight of corn cob (r = 0.987**) was found. The results of instrumental measuring of field crops transpiration under diverse moisture conditions at a concurrent monitoring of the meteorological elements spectra are rather unique. These results will be utilized in the effort to make calculations of the evapotranspiration in computing models more accurate.

  11. Transpiration 105 Place your message here. For maximum impact, use two or three sentences.

    E-print Network

    Koptur, Suzanne

    Transpiration 105 Place your message here. For maximum impact, use two or three sentences. Measuring Transpiration Transpiration is the evaporation of water from plants, which occurs mostly through of water movement in plants is called the "transpiration-cohesion hypothesis". When a plant wilts

  12. Near-optimal response of instantaneous transpiration efficiency to vapour pressure deficit, temperature and [CO2] in cotton (Gossypium hirsutum L.).

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The instantaneous transpiration efficiency (ITE, the ratio of photosynthesis rate to transpiration) is an important variable for crops, because it ultimately affects dry mass production per unit of plant water lost to the atmosphere. The theory that stomata optimize carbon uptake per unit water used...

  13. Transpiration cooling using air as a coolant

    SciTech Connect

    Kikkawa, Shinzo; Senda, Mamoru; Sakagushi, Katsuji; Shibutani, Hideki (Doshisha Univ., Kyoto (Japan))

    1993-02-01

    Transpiration cooling is one of the most effective techniques for protecting a surface exposed to a high-temperature gas stream. In the present paper, the transpiration cooling effectiveness was measured under steady state. Air as a coolant was transpired from the surface of a porous plate exposed to hot gas stream, and the transpiration rate was varied in the range of 0.001 [approximately] 0.006. The transpiration cooling effectiveness was evaluated by measuring the temperature of the upper surface of the plate. Also, a theoretical study was performed and it was clarified that the effectiveness increases with increasing transpiration rate and heat-transfer coefficient of the upper surface. Further, the effectiveness was expressed as a function of the blowing parameter only. The agreement between the experimental results and theoretical ones was satisfactory.

  14. Transpiration cooled throat for hydrocarbon rocket engines

    NASA Technical Reports Server (NTRS)

    May, Lee R.; Burkhardt, Wendel M.

    1991-01-01

    The objective for the Transpiration Cooled Throat for Hydrocarbon Rocket Engines Program was to characterize the use of hydrocarbon fuels as transpiration coolants for rocket nozzle throats. The hydrocarbon fuels investigated in this program were RP-1 and methane. To adequately characterize the above transpiration coolants, a program was planned which would (1) predict engine system performance and life enhancements due to transpiration cooling of the throat region using analytical models, anchored with available data; (2) a versatile transpiration cooled subscale rocket thrust chamber was designed and fabricated; (3) the subscale thrust chamber was tested over a limited range of conditions, e.g., coolant type, chamber pressure, transpiration cooled length, and coolant flow rate; and (4) detailed data analyses were conducted to determine the relationship between the key performance and life enhancement variables.

  15. REGULAR PAPER Effects of flooding on leaf development, transpiration,

    E-print Network

    Letts, Matthew

    REGULAR PAPER Effects of flooding on leaf development, transpiration, and photosynthesis photosynthetic rate, and reduced transpiration particularly in P. 9 jackii. The effects on foliar gas exchange Populus 9 jackii Á Riparian Á Stress tolerance Á Transpiration Abbreviations A Net photosynthetic rate

  16. Comparison of corn transpiration, eddy covariance, and soil water loss

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Stem flow gages are used to estimate plant transpiration, but only a few studies compare transpiration with other measures of soil water loss. The purpose of this study was to compare transpiration from stem flow measurements with soil water changes estimated by daily neutron probe readings. Monitor...

  17. Estimation of Soil Evaporation and Plant Transpiration of Sparse Steppes by Using Ground-based Infrared Thermal Images

    NASA Astrophysics Data System (ADS)

    Qiu, G. Y.; Feng, Y.

    2011-12-01

    Separately estimation of soil evaporation (E) and vegetation transpiration (T) is important for water management. In this study, a methodology to estimate the ratio of vegetation cover, soil evaporation and vegetation transpiration in a sparse steppe is developed based on a previous published model, the three-temperatures (3T) model. The input parameters of the model includes the surface temperatures of soil and vegetation (from thermal image), net radiation (estimated from surface temperature and solar radiation), and air temperature. The approach of unsupervised classification was used to separate the bare soil and vegetation pixels from the images. The areas with higher temperature could be regarded as the bare soil and E was estimated by the evaporation sub-model in the 3T model; while the areas with lower temperature could be regarded as pure vegetation and T was estimated by the transpiration sub-model in the 3T model. Afterward, the estimated E and T were converted into daily values and compared with the measured E and T by using Bowen Ratio and micro-lysimeter methods. Results show that the proposed approach is a useful way to separately estimated E and T in sparse steppe.

  18. The function of nocturnal transpiration

    NASA Astrophysics Data System (ADS)

    Pfautsch, Sebastian; Resco de Dios, Víctor; Loik, Michael; Tissue, David

    2014-05-01

    Nocturnal transpiration is an important source of water loss, accounting for up to 25% of daytime transpiration in some species. Nocturnal water losses cannot be explained under the prevailing 'paradigm' of optimizing carbon gain while minimizing water loss because carbon fixation does not occur at night. Alternative explanations regarding the function and potential evolutionary advantage of nocturnal transpiration have been proposed, such as enhanced nutrient uptake and transport or delivery of O2 to parenchyma cells for respiration. However, recent evidence suggests that the role of nocturnal transpiration in supplementing the overall plant nutrient budget is relatively small, and the O2 hypothesis is difficult to test experimentally. Here, we propose that the main function of nocturnal transpiration (and water transport) is to prevent catastrophic xylem failure by restoring depleted stem 'capacitors' and enhancing early morning CO2 uptake, as stomata 'prepare' for daytime conditions. Nocturnal sap flux was highest in Eucalyptus grandis trees in the field following a heat wave (reaching 47C with VPDs > 8kPa in the daytime) generating maximal daytime water losses compared with cooler and lower VPD periods, indicating the importance of nocturnal stomatal conductance for stem refilling. Moreover, we observed that the time for stomata to respond to light early in the morning (dawn) across 25 different genotypes of E. camaldulensis in a glasshouse was shortest in those genotypes with highest nocturnal stomatal conductance, which was also correlated with higher daytime photosynthesis. This observation is consistent with previous observations that nocturnal stomatal conductance is partially controlled by the clock, which is utilised to anticipate daytime conditions. Data from the literature suggests that eucalypts respond similarly to other C3 species, suggesting that mechanisms regulating night-time transpiration may be universal.

  19. Rootstock control of scion transpiration and its acclimation to water deficit are controlled by different genes.

    PubMed

    Marguerit, Elisa; Brendel, Oliver; Lebon, Eric; Van Leeuwen, Cornelis; Ollat, Nathalie

    2012-04-01

    The stomatal control of transpiration is one of the major strategies by which plants cope with water stress. Here, we investigated the genetic architecture of the rootstock control of scion transpiration-related traits over a period of 3 yr. The rootstocks studied were full sibs from a controlled interspecific cross (Vitis vinifera cv. Cabernet Sauvignon × Vitis riparia cv. Gloire de Montpellier), onto which we grafted a single scion genotype. After 10 d without stress, the water supply was progressively limited over a period of 10 d, and a stable water deficit was then applied for 15 d. Transpiration rate was estimated daily and a mathematical curve was fitted to its response to water deficit intensity. We also determined ?(13) C values in leaves, transpiration efficiency and water extraction capacity. These traits were then analysed in a multienvironment (year and water status) quantitative trait locus (QTL) analysis. Quantitative trait loci, independent of year and water status, were detected for each trait. One genomic region was specifically implicated in the acclimation of scion transpiration induced by the rootstock. The QTLs identified colocalized with genes involved in water deficit responses, such as those relating to ABA and hydraulic regulation. Scion transpiration rate and its acclimation to water deficit are thus controlled genetically by the rootstock, through different genetic architectures. PMID:22335501

  20. The dynamic role of root-water uptake in coupling potential to actual transpiration

    E-print Network

    Katul, Gabriel

    The dynamic role of root-water uptake in coupling potential to actual transpiration Chun-Ta Lai a) and potential (Ep) transpiration above a grass-covered forest clearing was investigated numerically potential and actual transpiration and accounts for root-uptake eciency, potential transpiration rate

  1. Terrestrial water fluxes dominated by transpiration.

    PubMed

    Jasechko, Scott; Sharp, Zachary D; Gibson, John J; Birks, S Jean; Yi, Yi; Fawcett, Peter J

    2013-04-18

    Renewable fresh water over continents has input from precipitation and losses to the atmosphere through evaporation and transpiration. Global-scale estimates of transpiration from climate models are poorly constrained owing to large uncertainties in stomatal conductance and the lack of catchment-scale measurements required for model calibration, resulting in a range of predictions spanning 20 to 65 per cent of total terrestrial evapotranspiration (14,000 to 41,000 km(3) per year) (refs 1, 2, 3, 4, 5). Here we use the distinct isotope effects of transpiration and evaporation to show that transpiration is by far the largest water flux from Earth's continents, representing 80 to 90 per cent of terrestrial evapotranspiration. On the basis of our analysis of a global data set of large lakes and rivers, we conclude that transpiration recycles 62,000 ± 8,000 km(3) of water per year to the atmosphere, using half of all solar energy absorbed by land surfaces in the process. We also calculate CO2 uptake by terrestrial vegetation by connecting transpiration losses to carbon assimilation using water-use efficiency ratios of plants, and show the global gross primary productivity to be 129 ± 32 gigatonnes of carbon per year, which agrees, within the uncertainty, with previous estimates. The dominance of transpiration water fluxes in continental evapotranspiration suggests that, from the point of view of water resource forecasting, climate model development should prioritize improvements in simulations of biological fluxes rather than physical (evaporation) fluxes. PMID:23552893

  2. Seasonal, synoptic and diurnal variation of atmospheric water-isotopologues in the boundary layer of Southwestern Germany caused by plant transpiration, cold-front passages and dewfall.

    NASA Astrophysics Data System (ADS)

    Christner, Emanuel; Dyroff, Christoph; Kohler, Martin; Zahn, Andreas; Gonzales, Yenny; Schneider, Matthias

    2013-04-01

    Atmospheric water is an enormously crucial trace gas. It is responsible for ~70 % of the natural greenhouse effect (Schmidt et al., JGR, 2010) and carries huge amounts of latent heat. The isotopic composition of water vapor is an elegant tracer for a better understanding and quantification of the extremely complex and variable hydrological cycle in Earth's atmosphere (evaporation, cloud condensation, rainout, re-evaporation, snow), which in turn is a prerequisite to improve climate modeling and predictions. As H216O, H218O and HDO differ in vapor pressure and mass, isotope fractionation occurs due to condensation, evaporation and diffusion processes. In contrast to that, plants are able to transpire water with almost no isotope fractionation. For that reason the ratio of isotopologue concentrations in the boundary layer (BL) provides, compared to humidity measurements alone, independent and additional constraints for quantifying the strength of evaporation and transpiration. Furthermore the isotope ratios contain information about transport history of an air mass and microphysical processes, that is not accessible by humidity measurements. Within the project MUSICA (MUlti-platform remote Sensing of Isotopologues for investigating the Cycle of Atmospheric water) a commercial Picarro Analyzer L2120-i is operated at Karlsruhe in Southwestern Germany, which is continuously measuring the isotopologues H216O, HDO and H218O of atmospheric water vapor since January 2012. A one year record of H216O, HDO and H218O shows clear seasonal, synoptic and diurnal characteristics and reveals the main driving processes affecting the isotopic composition of water vapor in the Middle European BL. Changes in continental plant transpiration and evaporation throughout the year lead to a slow seasonal HDO/H216O-variation, that cannot be explained by pure Rayleigh condensation. Furthermore, cold-front passages from NW lead to fast and pronounced depletion of the HDO/H216O-ratio within minutes. Superimposed to these variations are local diurnal processes like dewfall, which cause a diurnal pattern captured by the deuterium excess.

  3. Estimation of Transpiration and Water Use Efficiency Using Satellite and Field Observations

    NASA Technical Reports Server (NTRS)

    Choudhury, Bhaskar J.; Quick, B. E.

    2003-01-01

    Structure and function of terrestrial plant communities bring about intimate relations between water, energy, and carbon exchange between land surface and atmosphere. Total evaporation, which is the sum of transpiration, soil evaporation and evaporation of intercepted water, couples water and energy balance equations. The rate of transpiration, which is the major fraction of total evaporation over most of the terrestrial land surface, is linked to the rate of carbon accumulation because functioning of stomata is optimized by both of these processes. Thus, quantifying the spatial and temporal variations of the transpiration efficiency (which is defined as the ratio of the rate of carbon accumulation and transpiration), and water use efficiency (defined as the ratio of the rate of carbon accumulation and total evaporation), and evaluation of modeling results against observations, are of significant importance in developing a better understanding of land surface processes. An approach has been developed for quantifying spatial and temporal variations of transpiration, and water-use efficiency based on biophysical process-based models, satellite and field observations. Calculations have been done using concurrent meteorological data derived from satellite observations and four dimensional data assimilation for four consecutive years (1987-1990) over an agricultural area in the Northern Great Plains of the US, and compared with field observations within and outside the study area. The paper provides substantive new information about interannual variation, particularly the effect of drought, on the efficiency values at a regional scale.

  4. Transpiration and CO/sub 2/ fixation of selected desert shrubs as related to soil-water potential

    SciTech Connect

    Clark, S.B.; Letey, J. Jr.; Lunt, O.R.; Wallace, A.; Kleinkopf, G.E.; Romney, E.M.

    1980-01-01

    In desert plants, transpiration rates decreased before photosynthetic rates when plants were entering a period of water stress. This may have adaptive consequences. A difference of -5 bars in the soil-moisture potential had considerable importance in reducing the rate of transpiration. In Helianthus annuus L. (sunflower) the photosynthetic rate decreased before the transpiration rate in contrast to Great Basin-Mojave Desert plants, and the changes occurred with a -1 bar difference in soil-moisture potential. Morphological changes in three desert plant species (Artemisia tridentata Nutt., Ambrosia dumosa (Gray) Payne, Larrea tridentata (Ses. Moc. ex DC) Cov.) as the soil-moisture potential decreased are given. With a mesic species, H. annuus, 20% reduction in photosynthesis and transpiration was reached at higher soil-moisture potentials than with the desert plants. Loss of net photosynthesis occurred in A. dumosa (a summer deciduous shrub) as PSI soil reached -48 bars in the field, whereas L. tridentata (an evergreen shrub) at the same time was able to maintain a water potential difference between soil and plant of -10 to -15 bars and continue net CO/sub 2/ gain well into the summer months.

  5. Transpiration: How Much Water Does a Tree Transpire in One Day?

    NSDL National Science Digital Library

    This activity has students construct a small terrarium that will allow them to observe and measure the water given off through transpiration. Students will be able to recognize transpiration and explain its value to the plant. They will also be able to explain how transpiration affects climate. The student's guide has an overall description of the activity, a list of materials, the procedure, and observations and questions. The teacher's guide contains detailed background material, learning goals, alignment to national standards, grade level/time, details on materials and preparation, procedure, assessment ideas, and modifications for alternative learners.

  6. Numerical Analysis of Convection/Transpiration Cooling

    NASA Technical Reports Server (NTRS)

    Glass, David E.; Dilley, Arthur D.; Kelly, H. Neale

    1999-01-01

    An innovative concept utilizing the natural porosity of refractory-composite materials and hydrogen coolant to provide CONvective and TRANspiration (CONTRAN) cooling and oxidation protection has been numerically studied for surfaces exposed to a high heat flux, high temperature environment such as hypersonic vehicle engine combustor walls. A boundary layer code and a porous media finite difference code were utilized to analyze the effect of convection and transpiration cooling on surface heat flux and temperature. The boundary, layer code determined that transpiration flow is able to provide blocking of the surface heat flux only if it is above a minimum level due to heat addition from combustion of the hydrogen transpirant. The porous media analysis indicated that cooling of the surface is attained with coolant flow rates that are in the same range as those required for blocking, indicating that a coupled analysis would be beneficial.

  7. Numerical Analysis of Convection/Transpiration Cooling

    NASA Technical Reports Server (NTRS)

    Glass, David E.; Dilley, Arthur D.; Kelly, H. Neale

    1999-01-01

    An innovative concept utilizing the natural porosity of refractory-composite materials and hydrogen coolant to provide CONvective and TRANspiration (CONTRAN) cooling and oxidation protection has been numerically studied for surfaces exposed to a high heat flux high temperature environment such as hypersonic vehicle engine combustor walls. A boundary layer code and a porous media finite difference code were utilized to analyze the effect of convection and transpiration cooling on surface heat flux and temperature. The boundary layer code determined that transpiration flow is able to provide blocking of the surface heat flux only if it is above a minimum level due to heat addition from combustion of the hydrogen transpirant. The porous media analysis indicated that cooling of the surface is attained with coolant flow rates that are in the same range as those required for blocking, indicating that a coupled analysis would be beneficial.

  8. Fruit transpiration in kiwifruit: environmental drivers and predictive model

    PubMed Central

    Montanaro, Giuseppe; Dichio, Bartolomeo; Xiloyannis, Cristos; Lang, Alexander

    2012-01-01

    Background and aims In most fruit crops, storage quality varies greatly between regions and seasons, causing significant commercial loss. Understanding the sources of this variability will contribute to the knowledge of fruit developmental physiology and may also benefit commercial fruit production via altered managements that reduce it or forecasts that predict it. A causal-chain relationship is proposed to help elucidate the sources of variability in fruit storage quality: the weather ?(i)? fruit transpiration ?(ii)? fruit calcium ?(iii)? fruit storage quality. This paper explores the first link of this hypothesis, ?(i)?, for Hayward kiwifruit using field measurements of fruit transpiration rate and concurrent meteorological recordings. The aims are to identify the key environmental variables driving fruit transpiration and develop a predictive fruit transpiration model. Methodology Fruit transpiration was determined hourly over several 24-h periods by recording weight loss of detached fruit, on Days 23, 35, 49, 65, 94 and 140 after full bloom. Meteorological records were made every 15 min throughout the season at an adjacent regional weather station. A model of fruit transpiration was developed in which the usual meteorological variables (radiation, temperature, windspeed and relative humidity) were incorporated in a Fick's Law transpiration flux equation. Principal results Fruit transpiration rate (i.e. the molar flux density, mmol cm?2 h?1) varied diurnally and decreased during the season. The dominant fruit variable governing transpiration rate was skin conductance and the dominant environmental variables were relative humidity and temperature. Radiation and windspeed were not significantly influential. Conclusions The model provides a good fit to the fruit transpiration rate measurements regardless of the time of day/night or the stage of fruit development. The model allows reasonably accurate and continuous predictions of fruit transpiration rate throughout fruit development based on standard meteorological recordings. It also allows estimates of cumulative fruit transpiration throughout the season. PMID:23136639

  9. Tritium Concentrations in Environmental Samples and Transpiration Rates from the Vicinity of Mary's Branch Creek and Background Areas, Barnwell, South Carolina, 2007-2009

    USGS Publications Warehouse

    Vroblesky, Don A.; Canova, Judy L.; Bradley, Paul M.; Landmeyer, James E.

    2009-01-01

    Tritium in groundwater from a low-level radioactive waste disposal facility near Barnwell, South Carolina, is discharging to Mary's Branch Creek. The U.S. Geological Survey conducted an investigation from 2007 to 2009 to examine the tritium concentration in trees and air samples near the creek and in background areas, in groundwater near the creek, and in surface water from the creek. Tritium was found in trees near the creek, but not in trees from background areas or from sites unlikely to be in direct root contact with tritium-contaminated groundwater. Tritium was found in groundwater near the creek and in the surface water of the creek. Analysis of tree material has the potential to be a useful tool in locating shallow tritium-contaminated groundwater. A tritium concentration of 1.4 million picocuries per liter was measured in shallow groundwater collected near a tulip poplar located in an area of tritium-contaminated groundwater discharge. Evapotranspiration rates from the tree and tritium concentrations in water extracted from tree cores indicate that during the summer, this tulip poplar may remove more than 17.1 million picocuries of tritium per day from the groundwater that otherwise would discharge to Mary's Branch Creek. Analysis of air samples near the tree showed no evidence that the transpirative release of tritium to the air created a vapor hazard in the forest.

  10. J. AMER. SOC. HORT. SCI. 126(5):638643. 2001. Optimization of Transpiration and Potential Growth

    E-print Network

    Lieth, J. Heinrich

    J. AMER. SOC. HORT. SCI. 126(5):638­643. 2001. Optimization of Transpiration and Potential Growth, microcalorimetry, potential growth, respiration rate, Rosa �hybrida, transpiration ABSTRACT. Physical transpiration rate, stomatal conductance, and specific growth rate of very young leaflets of `Kardinal' rose

  11. Plant Populations and Seeding Rates for Soybeans

    E-print Network

    Holland, Jeffrey

    Plant Populations and Seeding Rates for Soybeans Andrew P. Robinson Department of Agronomy www input costs for soybean growers, so it's important for growers to plant the right amount of seed to minimize input costs and increase profitability. Seeding rate, plant population, and row spacing are tied

  12. Deposition control using transpiration: Final report

    SciTech Connect

    Kozlu, H.; Louis, J.F.

    1986-11-01

    An experimental and theoretical study of deposition of small particles is presented to evaluate the concept of transpiration as a deposition control strategy. The application of this work is the control of the deposition of small particles (0.5 to 3 ..mu..m) in turbines burning fuels derived from coal. The study is carried out in a wind tunnel facility containing a flat porous transpired section. Similar flows and particle motions are achieved by choosing the proper Reynolds and Stokes numbers representative of the conditions found in industrial gas turbines. Measurements of the velocity profiles were conducted for high injection rates (1.5% < F < 3%). A theory developed for the transpired turbulent boundary layer, which is described by an ''outer boundary layer'' entraining the transpired flow for large injection rates, agrees well with the experimental data. Concentration profiles of glass particles of both very narrow and wide size distributions were conducted for different injection rates under isothermal conditions. The measurements indicate clearly the conditions under which transpiration can prevent the deposition of particles and they show the effect of particle size. The interaction between transpiration and the inertial impaction of particulates is determined in an experimental set-up using an identical inclined transpired plate. Using the experimental data, the effect of the density of particles on concentration profiles is predicted. Present study also provides a clear insight into the turbulent diffusion of particles for a Stokes number of between 1 and 3.5 (and a turbulent Schmidt number range of 2 to 6). The turbulent Schmidt numbers obtained from the measurements are in agreement with the theoretical prediction of Tchen. 26 refs., 25 figs.

  13. Interannual Variation in Stand Transpiration is Dependent Upon Tree Species

    NASA Astrophysics Data System (ADS)

    Ewers, B. E.; Mackay, D. S.; Burrows, S. N.; Ahl, D. E.; Samanta, S.

    2003-12-01

    In order to successfully predict transpirational water fluxes from forested watersheds, interannual variability in transpiration must be quantified and understood. In a heterogeneous forested landscape in northern Wisconsin, we quantified stand transpiration across four forest cover types representing more than 80 percent of the land area in order to 1) quantify differences in stand transpiration and leaf area over two years and 2) determine the mechanisms governing the changes in transpiration over two years. We measured sap flux in eight trees of each tree species in the four cover types. We found that in northern hardwoods, the leaf area of sugar maple increased between the two measurement years with transpiration per unit ground area increasing even more than could be explained by leaf area. In an aspen stand, tent caterpillars completely defoliated the stand for approximately a month until a new set of leaves flushed out. The new set of leaves resulted in a lower leaf area but the same transpiration per unit leaf area indicating there was no physiological compensation for the lower leaf area. At the same time, balsam fir growing underneath the aspen increased their transpiration rate in response to greater light penetration through the dominant aspen canopy Red pine had a thirty percent change in leaf area within a growing season due to multiple cohorts of leaves and transpiration followed this leaf area dynamic. In a forested wetland, white cedar transpiration was proportional to surface water depth between the two years. Despite the specific tree species' effects on stand transpiration, all species displayed a minimum water potential regulation resulting in a saturating response of transpiration to vapor pressure deficit that did not vary across the two years. This physiological set point will allow future water flux models to explain mechanistically interannual variability in transpiration of this and similar forests.

  14. Correlation of thermophoretically-modified small particle diffusional deposition rates in forced convection systems with variable properties, transpiration cooling and/or viscous dissipation

    NASA Technical Reports Server (NTRS)

    Gokoglu, S. A.; Rosner, D. E.

    1984-01-01

    A cooled object (heat exchanger tube or turbine blade) is considered to be immersed in a hot fluid stream containing trace amounts of suspended vapors and/or small particles. Numerical prediction calculations were done for self-similar laminar boundary layers and law-of-the-wall turbulent boundary layers. Correlations are presented for the effect of thermophoresis in the absence of transpiration cooling and viscous dissipation; the effect of real suction and blowing in the absence of thermophoresis; the effect of viscous dissipation on thermophoresis in the absence of transpiration cooling; and the combined effect of viscous dissipation and transpiration cooling on thermophoresis. The final correlation, St/St-sub-zero, is insensitive to particle properties, Euler number, and local mainstream temperature.

  15. A high CO2 -driven decrease in plant transpiration leads to perturbations in the hydrological cycle and may link terrestrial and marine loss of biodiversity: deep-time evidence.

    NASA Astrophysics Data System (ADS)

    Steinthorsdottir, Margret; Woodward, F. Ian; Surlyk, Finn; McElwain, Jennifer C.

    2013-04-01

    CO2 is obtained and water vapor simultaneously transpired through plant stomata, driving the water uptake of roots. Stomata are key elements of the Earth's hydrological cycle, since a large part of the evapotranspiration from the surface to the atmosphere takes place via stomatal pores. Plants exercise stomatal control, by adjusting stomatal size and/or density in order to preserve water while maintaining carbon uptake for photosynthesis. A global decrease in stomatal density and/or size causes a decrease in transpiration and has the potential to increase global runoff. Here we show, from 91 fossil leaf cuticle specimens from the Triassic/Jurassic boundary transition (Tr-J) of East Greenland, that both stomatal size and density decreased dramatically during the Tr-J, coinciding with mass extinctions, major environmental upheaval and a negative C-isotope excursion. We estimate that these developmental and structural changes in stomata resulted in a 50-60% drop in stomatal and canopy transpiration as calibrated using a stomatal model, based on empirical measurements and adjusted for fossil plants. We additionally present new field evidence indicating a change to increased erosion and bad-land formation at the Tr-J. We hypothesize that plant physiological responses to high carbon dioxide concentrations at the Tr-J may have increased runoff at the local and perhaps even regional scale. Increased runoff may result in increased flux of nutrients from land to oceans, leading to eutrophication, anoxia and ultimately loss of marine biodiversity. High-CO2 driven changes in stomatal and canopy transpiration therefore provide a possible mechanistic link between terrestrial ecological crisis and marine mass extinction at the Tr-J.

  16. Measurement of transpiration in Pinus taeda L. and Liquidambar styraciflua L. in an environmental chamber using tritiated water

    NASA Technical Reports Server (NTRS)

    Levy, G. F.; Sonenshine, D. E.; Czoch, J. K.

    1976-01-01

    Transpiration rates of loblolly pine (Pinus taeda L.) and sweetgum (Liquidambar styraciflua L.) were measured at two different atmospheric water vapor pressure deficits (V.P.D.) in a controlled environment growth chamber using tritiated water as a tracer. The trees were maintained in a sealed plant bed containing a hydroponic nutrient solution into which labeled water (spike) was introduced. Samples of leaves, chamber air, spiked nutrient solution and control water were assayed for ratio-activity using liquid scintillation techniques to determine transpiration rates. The transpiration rate of sweetgum in ml./hr./gm. (4.95) was found to be 5 times greater than that of loblolly pine (1.03) at 1.84 V.P.D. and 8 times greater at 6.74 V.P.D. (15.99 for sweetgum vs. 2.19 for pine). Transpiration (based on measurements of leaf radioactivity) in both species rose with increasing deficit; however sweetgum increased its output by 3 times while pine only doubled its rate. Cyclical changes in transpiration rates were noted in both species; the sweetgum cycle required a 6 hour interval whereas the pine cycle required a 9 hour interval.

  17. Agricultural and Forest Meteorology 107 (2001) 167175 Reduction of transpiration through foliar application of chitosan

    E-print Network

    Flury, Markus

    Agricultural and Forest Meteorology 107 (2001) 167­175 Reduction of transpiration through foliar of chitosan, a natural beta-1-4-linked glucosamine polymer, to reduce plant transpiration. Chitosan-chambers, where transpiration was measured by weighing pots. In an accompanying field study, water use

  18. Uncertainties in transpiration estimates ARISING FROM S. Jasechko et al. Nature 496, 347350 (2013)

    E-print Network

    Cai, Long

    Uncertainties in transpiration estimates ARISING FROM S. Jasechko et al. Nature 496, 347­350 (2013) How best to assess the respective importance of plant transpiration over evaporation from open waters. On the basis of data from lake catchments, Jasechko et al.1 conclude that transpiration accounts for 80

  19. Abscisic acid content, transpiration, and stomatal conductance as related to leaf age in plants Xanthium strumarium L

    Microsoft Academic Search

    K. Raschke; J. A. D. Zeevaart

    1976-01-01

    Among the four uppermost leaves of greenhouse-grown plants of Xanthium strumarium L., the content of abscisic acid per unit fresh or dry weight was highest in the youngest leaf and decreased gradually with increasing age of the leaves. Expressed per leaf, the second youngest leaf was richest in ABA; the amount of ABA per leaf declined only slightly as the

  20. Effects of Xylem pH on Transpiration from Wild-Type and flacca Tomato Leaves1

    PubMed Central

    Wilkinson, Sally; Corlett, Janet E.; Oger, Ludovic; Davies, William J.

    1998-01-01

    The pH of xylem sap from tomato (Lycopersicon esculentum) plants increased from pH 5.0 to 8.0 as the soil dried. Detached wild-type but not flacca leaves exhibited reduced transpiration rates when the artificial xylem sap (AS) pH was increased. When a well-watered concentration of abscisic acid (0.03 ?m) was provided in the AS, the wild-type transpirational response to pH was restored to flacca leaves. Transpiration from flacca but not from wild-type leaves actually increased in some cases when the pH of the AS was increased from 6.75 to 7.75, demonstrating an absolute requirement for abscisic acid in preventing stomatal opening and excessive water loss from plants growing in many different environments. PMID:9625724

  1. Numerical Simulation of Transpiration Cooling

    E-print Network

    Numerical Simulation of Transpiration Cooling through Porous Material Wolfgang Dahmen 1 , Thomas Gotzen 1 and Siegfried M¨uller 1 Bericht Nr. 374 September 2013 Key words: Transpiration cooling, porous School AICES (GSC 111). #12;Numerical simulation of transpiration cooling through porous material W

  2. Trends and rates of microevolution in plants

    Microsoft Academic Search

    Elizabeth Bone; Agnes Farres

    2001-01-01

    Evidence for rapid evolutionary change in plants in response to changing environmental conditions is widespread in the literature. However, evolutionary change in plant populations has not been quantified using a rate metric that allows for comparisons between and within studies. One objective of this paper is to estimate rates of evolution using data from previously published studies to begin a

  3. Transpiration Control Of Aerodynamics Via Porous Surfaces

    NASA Technical Reports Server (NTRS)

    Banks, Daniel W.; Wood, Richard M.; Bauer, Steven X. S.

    1993-01-01

    Quasi-active porous surface used to control pressure loading on aerodynamic surface of aircraft or other vehicle, according to proposal. In transpiration control, one makes small additions of pressure and/or mass to cavity beneath surface of porous skin on aerodynamic surface, thereby affecting rate of transpiration through porous surface. Porous skin located on forebody or any other suitable aerodynamic surface, with cavity just below surface. Device based on concept extremely lightweight, mechanically simple, occupies little volume in vehicle, and extremely adaptable.

  4. Transpiration dynamics of an Austrian Pine stand and its forest floor: identifying controlling conditions using artificial

    E-print Network

    Vrugt, Jasper A.

    Transpiration dynamics of an Austrian Pine stand and its forest floor: identifying controlling in governing the transpiration rates of an Austrian Pine stand and its forest floor. Latent heat flux densities of different depth intervals. Results show that forest floor transpiration dynamics can be adequately modelled

  5. Environmental and physiological regulation of transpiration in tropical forest gap species: the influence of boundary layer and hydraulic properties

    Microsoft Academic Search

    F. C. Meinzer; G. Goldstein; P. Jackson; N. M. Holbrook; M. V. Gutiérrez; J. Cavelier

    1995-01-01

    Environmental and physiological regulation of transpiration were examined in several gap-colonizing shrub and tree species during two consecutive dry seasons in a moist, lowland tropical forest on Barro Colorado Island, Panama. Whole plant transpiration, stomatal and total vapor phase (stomatal + boundary layer) conductance, plant water potential and environmental variables were measured concurrently. This allowed control of transpiration (E) to

  6. Transpiration purged optical probe

    DOEpatents

    2004-01-06

    An optical apparatus for clearly viewing the interior of a containment vessel by applying a transpiration fluid to a volume directly in front of the external surface of the optical element of the optical apparatus. The fluid is provided by an external source and transported by means of an annular tube to a capped end region where the inner tube is perforated. The perforation allows the fluid to stream axially towards the center of the inner tube and then axially away from an optical element which is positioned in the inner tube just prior to the porous sleeve. This arrangement draws any contaminants away from the optical element keeping it free of contaminants. In one of several embodiments, the optical element can be a lens, a viewing port or a laser, and the external source can provide a transpiration fluid having either steady properties or time varying properties.

  7. Evapotranspiration crop coefficients for mixed riparian plant community and transpiration crop coefficients for Common reed, Cottonwood and Peach-leaf willow in the Platte River Basin, Nebraska-USA

    NASA Astrophysics Data System (ADS)

    Irmak, S.; Kabenge, I.; Rudnick, D.; Knezevic, S.; Woodward, D.; Moravek, M.

    2013-02-01

    SummaryApplication of two-step approach of evapotranspiration (ET) crop coefficients (Kc) to "approximate" a very complex process of actual evapotranspiration (ETa) for field crops has been practiced by water management community. However, the use of Kc, and in particular the concept of growing degree days (GDD) to estimate Kc, have not been sufficiently studied for estimation of evaporative losses from riparian vegetation. Our study is one of the first to develop evapotranspiration crop coefficient (KcET) curves for mixed riparian vegetation and transpiration (TRP) crop coefficients (KcTRP) for individual riparian species as a function GDD through extensive field campaigns conducted in 2009 and 2010 in the Platte River Basin in central Nebraska, USA. KcTRP values for individual riparian vegetation species [Common reed (Phragmites australis), Cottonwood (Populus deltoids) and Peach-leaf willow (Salix amygdaloides)] were quantified from the TRP rates obtained using scaled-up canopy resistance from measured leaf-level stomatal resistance and reference evapotranspiration. The KcET and KcTRP curves were developed for alfalfa-reference (KcrET and KcrTRP) surface. The seasonal average mixed riparian plant community KcrET was 0.89 in 2009 and 1.27 in 2010. In 2009, the seasonal average KcrTRP values for Common reed, Cottonwood and Peach-leaf willow were 0.57, 0.51 and 0.62, respectively. In 2010, the seasonal average KcrTRP were 0.69, 0.62 and 0.83 for the same species, respectively. In general, TRP crop coefficients had less interannual variability than the KcrET. Response of the vegetation to flooding in 2010 played an important role on the interannual variability of KcrET values. We demonstrated good performance and reliability of developed GDD-based KcrTRP curves by using the curves developed for 2009 to predict TRP rates of individual species in 2010. Using the KcrTRP curves developed during the 2009 season, we were able to predict the TRP rates for Common reed, Cottonwood and Peach-leaf willow in 2010 within 7%, 8% and 13% accuracy, indicating a good performance of the two-step approach proposed in this study for estimating TRP for riparian vegetation. The surface conditions of the riparian ecosystem need to be considered when using the two-step approach to estimate ETa or TRP rates of riparian plant communities. The results of this study provide important water use information and data for riparian vegetation that can be used for more robust hydrologic/water balance analyses.

  8. Elevated CO2 decreases both transpiration flow and concentrations of Ca and Mg in the xylem sap of wheat.

    PubMed

    Houshmandfar, Alireza; Fitzgerald, Glenn J; Tausz, Michael

    2015-02-01

    The impact of elevated atmospheric [CO2] (e[CO2]) on plants often includes a decrease in their nutrient status, including Ca and Mg, but the reasons for this decline have not been clearly identified. One of the proposed hypotheses is a decrease in transpiration-driven mass flow of nutrients due to decreased stomatal conductance. We used glasshouse and Free Air CO2 Enrichment (FACE) experiments with wheat to show that, in addition to decrease in transpiration rate, e[CO2] decreased the concentrations of Ca and Mg in the xylem sap. This result suggests that uptake of nutrients is not only decreased by reduced transpiration-driven mass flow, but also by as yet unidentified mechanisms that lead to reduced concentrations in the xylem sap. PMID:25462978

  9. Environmental and biological controls of urban tree transpiration in the Upper Midwest

    NASA Astrophysics Data System (ADS)

    Peters, E. B.; McFadden, J.; Montgomery, R.

    2009-12-01

    Urban trees provide a variety of ecosystem services to urban and suburban areas, including carbon uptake, climate amelioration, energy reduction, and stormwater management. Tree transpiration, in particular, modifies urban water budgets by providing an alternative pathway for water after rain events. The relative importance of environmental and biological controls on transpiration are poorly understood in urban areas, yet these controls are important for quantifying and scaling up the ecosystem services that urban trees provide at landscape and regional scales and predicting how urban ecosystems will respond to climate changes. The objectives of our study were to quantify the annual cycle of tree transpiration in an urban ecosystem and to determine how different urban tree species and plant functional types respond to environmental drivers. We continuously measured whole-tree transpiration using thermal dissipation sap flow at four urban forest stands that were broadly representative of the species composition and tree sizes found in a suburban residential neighborhood of Minneapolis-Saint Paul, Minnesota. A total of 40 trees, representing different species, plant functional types, successional stages, and xylem anatomy, were sampled throughout the 2007 and 2008 growing seasons (April-November). At each site we monitored soil moisture, air temperature, and relative humidity continuously, and we measured leaf area index weekly. Urban tree transpiration was strongly correlated with diurnal changes in vapor pressure deficit and photosynthetically active radiation and with seasonal changes in leaf area index. We found that plant functional type better explained species differences in transpiration per canopy area than either successional stage or xylem anatomy, largely due to differences in canopy structure between conifer and broad-leaf deciduous trees. We also observed inter-annual differences in transpiration rates due to a mid-season drought and longer growing season in 2007, compared with the cooler, wetter conditions in 2008. These results were scaled to estimate the relative contribution of each tree type at the scale of a suburban landscape. The findings of this study have implications for understanding the role of trees in managing urban water budgets and predicting the impacts of climate change on urban ecosystem services.

  10. Vessel Contents During Transpiration-Embolisms and Refilling

    Microsoft Academic Search

    Martin J. Canny

    1997-01-01

    A test was made of the previous unexpected observation that embolized vessels were refilled during active transpiration. The contents of individual vessels in petioles of sunflower plants were examined, after snap-freezing at 2-h intervals during a day's transpiration, in the cryo-scanning electron microscope, and assessed for the presence of liquid or gas (embolism) contents. Concurrent measurements were made of irradiance,

  11. Effects of fly ash, Pseudomonas striata and Rhizobium on the reproduction of nematode Meloidogyne incognita and on the growth and transpiration of pea.

    PubMed

    Siddiqui, Zaki A; Singh, Lamabam Peter

    2005-01-01

    Glasshouse experiments were conducted twice to assess the ash amendments (0, 20, and 40% with soil), a phosphate solubilizing microorganism Pseudomonas striata and a root-nodule bacterium Rhizobium sp on the reproduction of root-knot nematode Meloidogyne incognita and on the growth and transpiration of pea. Amendments of fly ash with soil had no effect on transpiration. However, M. incognita reduced the rate of transpiration from 1st week onward after inoculation while inoculation of Rhizobium sp and P. striata increased transpiration from 1st week onward after their inoculation both in nematode inoculated and uninoculated plants. Increase in transpiration was greater when both organisms were inoculated together. Addition of 20 and 40% fly ash with soil was beneficial for plant growth both in nematode inoculated and uninoculated plants. Inoculation of above organisms also increases plant growth of nematode inoculated and uninoculated plants in different fly ash soil mixture but increase in growth was greater when both organisms were inoculated together. Use of 20% fly ash increased galling and nematode multiplication over plants grown in without fly ash while 40% fly ash had adverse effect on galling and nematode multiplication. Rhizobium sp had greater adverse effect on galling and nematode multiplication than P. striata. Use of both organisms together had greater adverse effect on galling and nematode multiplication than caused by either of them alone. Highest reduction in galling and nematode multiplication was observed when both organisms were used in 40% fly ash amended soil. However, highest transpiration was observed in plants without nematodes and inoculated with both organisms together both in with or without fly ash amended soil. PMID:16114471

  12. Sap fluxupscaled canopy transpiration, stomatal conductance, and water use efficiency in an old growth forest in the Great Lakes region

    E-print Network

    Ewers, Brent E.

    Sap flux­upscaled canopy transpiration, stomatal conductance, and water use efficiency in an old measurements provides a means to study plant stomatal conductance and the relationship between transpiration forest in Michigan, upscaled to canopy transpiration, and calculated canopy conductance. We also measured

  13. Thermodynamics of cuticular transpiration Allen G. Gibbs *

    E-print Network

    Ahmad, Sajjad

    Review Thermodynamics of cuticular transpiration§ Allen G. Gibbs * School of Life Sciences, 4505 S . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1066 2. Effects of temperature on cuticular transpiration that water will tend to leave via transpiration through the integument. These problems are exacerbated

  14. Transpiration Cooling Experiment

    NASA Technical Reports Server (NTRS)

    Song, Kyo D.; Ries, Heidi R.; Scotti, Stephen J.; Choi, Sang H.

    1997-01-01

    The transpiration cooling method was considered for a scram-jet engine to accommodate thermally the situation where a very high heat flux (200 Btu/sq. ft sec) from hydrogen fuel combustion process is imposed to the engine walls. In a scram-jet engine, a small portion of hydrogen fuel passes through the porous walls of the engine combustor to cool the engine walls and at the same time the rest passes along combustion chamber walls and is preheated. Such a regenerative system promises simultaneously cooling of engine combustor and preheating the cryogenic fuel. In the experiment, an optical heating method was used to provide a heat flux of 200 Btu/sq. ft sec to the cylindrical surface of a porous stainless steel specimen which carried helium gas. The cooling efficiencies by transpiration were studied for specimens with various porosity. The experiments of various test specimens under high heat flux have revealed a phenomenon that chokes the medium flow when passing through a porous structure. This research includes the analysis of the system and a scaling conversion study that interprets the results from helium into the case when hydrogen medium is used.

  15. Possible role of alternative respiration in temperature rise of water stressed plants

    Microsoft Academic Search

    Sanjay Kumar; Suresh K Sinha

    1994-01-01

    Role of alternative respiration, a thermogenic pathway, was evaluated in temperature rise of water stressed plants. Transpiration\\u000a rate, plant temperature and respiratory dynamics were monitored in field grown irrigated and unirrigated sorghum(Sorghum vulgare Pers.) hybrid CSH 6 and pearl millet(Pennirelum typhoider (Burm. f.) Stapt and Hubbard) var. J 104 for 22 days. Transpiration rate of irrigated plants was always higher

  16. Bayesian analysis for uncertainty estimation of a canopy transpiration model

    Microsoft Academic Search

    S. Samanta; D. S. Mackay; M. K. Clayton; E. L. Kruger; B. E. Ewers

    2007-01-01

    A Bayesian approach was used to fit a conceptual transpiration model to half-hourly transpiration rates for a sugar maple (Acer saccharum) stand collected over a 5-month period and probabilistically estimate its parameter and prediction uncertainties. The model used the Penman-Monteith equation with the Jarvis model for canopy conductance. This deterministic model was extended by adding a normally distributed error term.

  17. Idaho Chemical Processing Plant failure rate database

    SciTech Connect

    Alber, T.G.; Hunt, C.R.; Fogarty, S.P.; Wilson, J.R.

    1995-08-01

    This report represents the first major upgrade to the Idaho Chemical Processing Plant (ICPP) Failure Rate Database. This upgrade incorporates additional site-specific and generic data while improving on the previous data reduction techniques. In addition, due to a change in mission at the ICPP, the status of certain equipment items has changed from operating to standby or off-line. A discussion of how this mission change influenced the relevance of failure data also has been included. This report contains two data sources: the ICPP Failure Rate Database and a generic failure rate database. A discussion is presented on the approaches and assumptions used to develop the data in the ICPP Failure Rate Database. The generic database is included along with a short discussion of its application. A brief discussion of future projects recommended to strengthen and lend credibility to the ICPP Failure Rate Database also is included.

  18. The influence of acid mist upon transpiration, shoot water potential and pressure—volume curves

    E-print Network

    Paris-Sud XI, Université de

    The influence of acid mist upon transpiration, shoot water potential and pressure and night transpiration rates were determined on 16/11/87 for 10 entire seedlings, of pH 2.5 and pH 5 transpiration rates were 1.19 ± 0.06 mmol's-1.tree-1 (day) and 0.54 ± 0.06 mmol's-1.tree-1 (night) for whole

  19. Ann. Sci. forest. 1974, 31 (2), 97-109. TUDE EXPRIMENTALE D E L A TRANSPIRATION

    E-print Network

    Paris-Sud XI, Université de

    Ann. Sci. forest. 1974, 31 (2), 97-109. �TUDE EXP�RIMENTALE D E L A TRANSPIRATION ET D U menée en pots étanches, par la méthode gravimétrique, qui permet de suivre la transpiration des plants saisonnier de transpiration (fig. 1 et 2), indépendant des variations de surfaces évaporantes et des

  20. Transpiration coefficients for three Great Basin shrubs

    Microsoft Academic Search

    Aaron L. Steinwand; Robert F. Harrington; David P. Groeneveld

    2001-01-01

    Transpiration by desert phreatophytes is poorly understood, and the few existing data are difficult to extrapolate spatially. This study developed transpiration coefficients (Kc) for Atriplex lentiformis ssp.torreyi , Chrysothamnus nauseosus and Sarcobatus vermiculatus to estimate transpiration using vegetation cover measurements. The Kc were developed from stomatal conductance, reference evapotranspiration (ETr), and modeled leaf area index (LAI). Transpiration estimates using the

  1. Biophysical control of whole tree transpiration under an urban environment in Northern China

    NASA Astrophysics Data System (ADS)

    Chen, Lixin; Zhang, Zhiqiang; Li, Zhandong; Tang, Jianwu; Caldwell, Peter; Zhang, Wenjuan

    2011-05-01

    SummaryUrban reforestation in China has led to increasing debate about the impact of urban trees and forests on water resources. Although transpiration is the largest water flux leaving terrestrial ecosystems, little is known regarding whole tree transpiration in urban environments. In this study, we quantified urban tree transpiration at various temporal scales and examined the biophysical control of the transpiration pattern under different water conditions to understand how trees survive in an urban environment. Concurrent with microclimate and soil moisture measurements, transpiration from C edrus deodara(Roxb)Loud ., Zelkova schneideriana Hend.-Mazz., Euonymus bungeanus Maxim., and Metasequoia glyptostroboides Hu et cheng was measured over a 2-year period using thermal dissipation probe (TDP) techniques. The average monthly transpiration rates reached 12.78 ± 0.73 (S.E.) mm, 1.79 ± 0.16 mm, 10.18 ± 0.55 mm and 19.28 ± 2.24 mm for C. deodara, Z.schneideriana, E. bungeanus and M. glyptostroboides, respectively. Transpiration rates from M. glyptostroboides reported here may need further study as this species showed much higher sap flows and greater transpiration fluctuation under different environmental conditions than other species. Because of deep soil moisture supply, summer dry spells did not reduce transpiration rates even when tree transpiration exceeded rainfall. While vapor pressure deficit ( VPD) was the dominant environmental factor on transpiration, trees controlled canopy conductance effectively to limit transpiration in times of water stress. Our results provide evidence that urban trees could adopt strong physiological control over transpiration under high evaporative demands to avoid dehydration and can make use of water in deeper soil layers to survive summer dry spells. Moreover, urban trees have the ability to make the best use of precipitation when it is limited, and are sensitive to soil and air dryness.

  2. Quantifying Understory Transpiration in a Semiarid Riparian Area

    NASA Astrophysics Data System (ADS)

    McGuire, R. R.; Scott, R. L.

    2005-12-01

    One of the most challenging components to estimate when determining water budgets in semiarid basins is riparian evapotranspiration (ET). Much research has been conducted upon riparian overstory vegetation in these areas; however understory vegetation water use has been ignored due to measurement difficulties and the belief that its quantity is negligible. To better understand the magnitude of understory water use in a semiarid riparian ecosystem, we measured whole plant transpiration of the dominant understory shrub, seep willow (Baccharis salicifolia), along a perennial reach of the San Pedro River in southeastern Arizona. . Shrub transpiration was monitored using the heat balance sap flow technique and was compared under two environmental conditions: a shrub patch located in a more open environment with decreased overstory canopy cover, and a more closed shrub patch situated more directly underneath a cottonwood (Populus fremontii) forest canopy. Despite the differences in atmospheric forcing, stand-level transpiration at both sites was similar and indicated that transpiration was rarely demand-limited. Growing season transpiration totals for seep willow were much greater than precipitation and of comparable magnitude to the overstory cottonwood transpiration. These results suggest that understory water use can be an important component of a riparian water budget, especially in regions like the western U.S. where evaporative demand is often high.

  3. Spatial patterns of simulated transpiration response to climate variability in a snow dominated mountain ecosystem

    USGS Publications Warehouse

    Christensen, L.; Tague, C.L.; Baron, J.S.

    2008-01-01

    Transpiration is an important component of soil water storage and stream-flow and is linked with ecosystem productivity, species distribution, and ecosystem health. In mountain environments, complex topography creates heterogeneity in key controls on transpiration as well as logistical challenges for collecting representative measurements. In these settings, ecosystem models can be used to account for variation in space and time of the dominant controls on transpiration and provide estimates of transpiration patterns and their sensitivity to climate variability and change. The Regional Hydro-Ecological Simulation System (RHESSys) model was used to assess elevational differences in sensitivity of transpiration rates to the spatiotemporal variability of climate variables across the Upper Merced River watershed, Yosemite Valley, California, USA. At the basin scale, predicted annual transpiration was lowest in driest and wettest years, and greatest in moderate precipitation years (R2 = 0.32 and 0.29, based on polynomial regression of maximum snow depth and annual precipitation, respectively). At finer spatial scales, responsiveness of transpiration rates to climate differed along an elevational gradient. Low elevations (1200-1800 m) showed little interannual variation in transpiration due to topographically controlled high soil moistures along the river corridor. Annual conifer stand transpiration at intermediate elevations (1800-2150 m) responded more strongly to precipitation, resulting in a unimodal relationship between transpiration and precipitation where highest transpiration occurred during moderate precipitation levels, regardless of annual air temperatures. Higher elevations (2150-2600 m) maintained this trend, but air temperature sensitivities were greater. At these elevations, snowfall provides enough moisture for growth, and increased temperatures influenced transpiration. Transpiration at the highest elevations (2600-4000 m) showed strong sensitivity to air temperature, little sensitivity to precipitation. Model results suggest elevational differences in vegetation water use and sensitivity to climate were significant and will likely play a key role in controlling responses and vulnerability of Sierra Nevada ecosystems to climate change. Copyright ?? 2008 John Wiley & Sons, Ltd.

  4. Simulation of diurnal transpiration and photosynthesis of a water stressed soybean crop

    Microsoft Academic Search

    Albert Olioso; Toby N. Carlson; Nadine Brisson

    1996-01-01

    The diurnal course of photosynthesis and transpiration of different plants can exhibit a dissymmetric behaviour between the morning and the afternoon, a photosynthetic midday depression and a transpiration ‘plateau’. A field experiment conducted in a meditenanean climate allows us to identify these features for a soybean crop undergoing water stress. The experimental data also show that, before and after the

  5. Active and passive ion transport in relation to transpiration in Helianthus annuus

    Microsoft Academic Search

    D. J. F. Bowling

    1968-01-01

    The effect of transpiration on the uptake of K, Ca, NO3 and SO4 from two strengths of culture solution by Helianthus plants was investigated. In the dilute solution transpiration had no effect on the uptake of all the ions studied. In the more concentrated solution the uptake of K, NO3 and SO4 were found to be sensitive to changes in

  6. Role of transpiration suppression by evaporation of intercepted water in improving irrigation efficiency

    Microsoft Academic Search

    J. A. Tolk; T. A. Howell; J. L. Steiner; D. R. Krieg; A. D. Schneider

    1995-01-01

    Sprinkler irrigation efficiency declines when applied water intercepted by the crop foliage, or gross interception (Igross), as well as airborne droplets and ponded water at the soil surface evaporate before use by the crop. However, evaporation of applied water can also supply some of the atmospheric demands usually met by plant transpiration. Any suppression of crop transpiration from the irrigated

  7. CCMR: Modeling Transpiration with Porous Silicon Membranes

    NSDL National Science Digital Library

    Jilo, Allen

    2010-08-15

    The purpose of the project was to better understand the characteristics of porous silicon membranes and assess their possible applications, especially in the area of heat transfer. Porous silicon can be used in the modeling of transpiration in plants, where water is transported under negative pressure. If porous silicon is found to be able to hold high enough levels of tension (negative pressure), then it has great potential in cooling systems; it could act as a “self-driving pump” that would not need large amounts of external energy like most current systems.

  8. [Comparison of ecophysiological characteristics of seven plant species in semiarid loess hilly-gully region].

    PubMed

    Xu, Bing-cheng; Shan, Lun; Li, Feng-min

    2007-05-01

    The diurnal course of photosynthetic rate, transpiration rate, and leaf water potential (psi L) of five plant species in North Shaanxi loess hilly-gully region were measured in dry seasons. Based on the daily maximum photosynthetic and transpiration rates, daily total assimilation and transpiration, and diurnal change characteristics of psi L, the test plants were classified into different eco-adaptation types. Panicum virgatum L. had high photosynthetic rate, low transpiration rate and high water use efficiency (WUE), and its drought adaptation strategy was to delay dehydration by developing high psi L. Medicago sativa had high photosynthetic and transpiration rates but low WUE, while Lespedeza dahurica had low photosynthetic and transpiration rates and low WUE. Their drought adaptation strategies were the same, namely, by increasing psi L delay dehydration. Bothriochloa ischaemum had high photosynthetic rate, relative high transpiration rate and medium WUE, and its drought-resistant strategy was to decrease psi L to endure dehydration. Astragalus adsurgens had similar characteristics in diurnal courses of photosynthesis with B. ischaemum, and its drought adaption strategy was to delay dehydration by developing low psi psi L. PMID:17650846

  9. Use of high-resolution thermal infrared remote sensing and “three-temperature model” for transpiration monitoring in arid inland river catchment

    NASA Astrophysics Data System (ADS)

    Tian, Fei; Qiu, GuoYu; Lü, YiHe; Yang, YongHui; Xiong, Yujiu

    2014-07-01

    Based on high-resolution thermal infrared remote sensing and the three-temperature model (3T model), we developed a new algorithm for mapping transpiration. The necessary input parameters were surface temperature, air temperature, and solar radiation only. Therefore, in comparison with conventional methods, it is a simple and potentially valuable way to employ the thermal infrared remote sensing application. By using the proposed method, transpiration of sixteen types of typical vegetation in the upper and middle reaches of the Heihe River Basin in Northwestern China were calculated pixel by pixel. We evaluated modeled evapotranspiration with an eddy covariance (EC) result from the established regression equation, and a scatter correlation plot for the measured and estimated transpiration indicated that the model estimate is within acceptable limits, with a correlation coefficient of R2 = 0.796. Compared with the desert-oasis transitional zone, the maximum transpiration rate at the Gobi Desert presented a little earlier but was smaller. This great difference may imply that different types of plants have different water-use abilities and drought tolerances. Thus, the transpiration estimation with the 3T model, using high-resolution thermal infrared remote sensing data, can provide not only a bridge between large-scale and point observation with a measure of m2 from the infrared thermal imager, but also provide decision support for operational water management issues.

  10. Measurements of transpiration from Eucalyptus plantations, India, using deuterium tracing

    SciTech Connect

    Calder, I.R. [Inst. of Hydrology, Wallingford (United Kingdom); Swaminath, M.H. [Karnataka Forest Dept., Bangalore (India); Kariyappa, G.S.; Srinivasalu, N.V.; Murthy, K.V. [Mysore Paper Mills, Karnataka (India); Mumtaz, J. [Karnataka Forest Dept., Bangalore (India)

    1992-12-31

    Measurements of transpiration from individual trees in Eucalyptus plantations at four different sites in Karnataka, southern India, are presented. These show large (as much as tenfold) differences in the transpiration between pre and post monsoon periods; a reflection of the effects of soil moisture stress in the pre monsoon periods. For trees with diameters at breast height (DBH) less than 10 cm the transpiration rate of individual trees is proportional to the square of the DBH. For trees which are not experiencing soil water stress the daily transpiration rate of individual trees, q, is well represented by the relation: q= (6.6 {+-} 0.3)g m{sup 3}d{sup {minus}1} where g (m{sup 2}) is the tree basal area. On a unit ground area basis the transpiration rate, expressed as a depth per day, is given by the relation: E{sub t}= (0.66 {+-} 0.03)G (mm d{sup {minus}1}) where G (m{sup 2} ha{sup {minus}1}) is the total basal area per hectare. For all the sites studied, although there is evidence for the mining of soil water as roots penetrate deeper depths in the soil each year, there is no evidence for direct abstraction from the watertable.

  11. Nitrogen regulation of transpiration controls mass-flow acquisition of nutrients.

    PubMed

    Matimati, Ignatious; Verboom, G Anthony; Cramer, Michael D

    2014-01-01

    Transpiration may enhance mass-flow of nutrients to roots, especially in low-nutrient soils or where the root system is not extensively developed. Previous work suggested that nitrogen (N) may regulate mass-flow of nutrients. Experiments were conducted to determine whether N regulates water fluxes, and whether this regulation has a functional role in controlling the mass-flow of nutrients to roots. Phaseolus vulgaris were grown in troughs designed to create an N availability gradient by restricting roots from intercepting a slow-release N source, which was placed at one of six distances behind a 25 ?m mesh from which nutrients could move by diffusion or mass-flow (termed 'mass-flow' treatment). Control plants had the N source supplied directly to their root zone so that N was available through interception, mass-flow, and diffusion (termed 'interception' treatment). 'Mass-flow' plants closest to the N source exhibited 2.9-fold higher transpiration (E), 2.6-fold higher stomatal conductance (gs), 1.2-fold higher intercellular [CO2] (Ci), and 3.4-fold lower water use efficiency than 'interception' plants, despite comparable values of photosynthetic rate (A). E, gs, and Ci first increased and then decreased with increasing distance from the N source to values even lower than those of 'interception' plants. 'Mass-flow' plants accumulated phosphorus and potassium, and had maximum concentrations at 10mm from the N source. Overall, N availability regulated transpiration-driven mass-flow of nutrients from substrate zones that were inaccessible to roots. Thus when water is available, mass-flow may partially substitute for root density in providing access to nutrients without incurring the costs of root extension, although the efficacy of mass-flow also depends on soil nutrient retention and hydraulic properties. PMID:24231035

  12. Reference Canopy Stomatal Conductance Explains Spatiotemporal Patterns of Tree Transpiration

    Microsoft Academic Search

    M. M. Loranty; D. S. Mackay; B. E. Ewers; E. L. Kruger; E. Traver

    2007-01-01

    Increased heterogeneity in patterns of whole tree transpiration (EC) with increasing atmospheric vapor pressure deficit (D) suggests a dynamic response of sap flow velocity (JS) to environmental drivers. We hypothesized that differences in reference stomatal conductance (GSref), stomatal conductance at D = 1kPa, would explain the spatiotemporal dynamics of JS. Using a coupled model of plant hydraulic and biochemical processes

  13. Crown structure, radiation absorption, photosynthesis and transpiration 

    E-print Network

    Wang, Yingping

    . Among the four different structural properties studied, crown shape is least important for PAR absorption, photosynthesis and transpiration. For the Sitka spruce stand studied, transpiration was most sensitive to the total area of leaves within the tree...

  14. Transpiration during life cycle in controlled wheat growth

    NASA Technical Reports Server (NTRS)

    Volk, Tyler; Rummel, John D.

    1989-01-01

    A previously-developed model of wheat growth, designed for convenient incorporation into system-level models of advanced space life support systems is described. The model is applied to data from an experiment that grew wheat under controlled conditions and measured fresh biomass and cumulated transpiration as a function of time. The adequacy of modeling the transpiration as proportional to the inedible biomass, and an age factor which varies during the life cycle, are examined. Results indicate that during the main phase of vegetative growth in the first half of the life cycle, the rate of transpiration per unit mass of inedible biomass is more than double the rate during the phase of grain development and maturation during latter half of the life cycle.

  15. Environmental controls on saltcedar (Tamarix spp.) transpiration and stomatal conductance and implications for determining evapotranspiration by remote sensing

    NASA Astrophysics Data System (ADS)

    Nagler, P. L.; Glenn, E. P.; morino, K.

    2012-12-01

    Saltcedar is an introduced, salt-tolerant shrub that now dominates many flow-regulated western U.S. rivers. Saltcedar control programs have been implemented to salvage water and to allow the return of native vegetation to infested rivers. However, there is much debate about how much water saltcedar actually uses and the range of ecohydrological niches it occupies. Ground methods for measuring riparian zone ET have improved and there is considerable interest in developing remote sensing methods for saltcedar to conduct wide-area monitoring of water use. Both thermal band and vegetation index methods have been used to estimate riparian ET. However, several problems present themselves in applying existing remote sensing methods to riparian corridors. First, many riparian corridors are narrow and are surrounded by arid uplands, hence they cannot be treated as energetically closed systems, an assumption of thermal band methods that calculate ET as a residual in the surface energy balance. Second, contrary to the assumption that riparian phreatophytes typically grow under unstressed conditions since they are rooted into groundwater, we find that saltcedar stands are under substantial degrees of apparent moisture stress, exhibiting midday depression of transpiration and stomatal conductance, and decreases in stomatal conductance over the growing season as depth to groundwater increases. Furthermore, the degree of stress is site-specific, depending on local soil texture, salinity of the groundwater and distance from the river. This violates a key assumption of vegetation index methods for estimating ET. The implications of these findings for arid-zone riparian ecohydrology and for remote sensing methods that assume either a constant daily evaporative fraction or rate of stomatal conductance will be discussed using saltcedar stands measured in the Cibola NWR on the lower Colorado River as a case study. Daily rates of saltcedar transpiration ranged from 1.6-3.0 mm/m2 leaf/day, while LAI varied over a narrower range, from 2.0 - 2.9. Differences in leaf-level transpiration were due to differences in stomatal conductance among sites. Sites close to the river had higher transpiration rates than sites further away, and sites with more saline water had lower leaf-level transpiration rates. Leaf-level transpiration rates were higher in June and July, when aquifers were closer to the surface, than in August and September, when water levels had dropped. High transpiration rates were associated with finer textured soil compared to plants growing in sandy soils. Low transpiration rates were manifested by moderate to severe midday depression of stomatal conductance and transpiration. These limitations constrained the rate of saltcedar ET to about 40% of ETo, and also reduced the accuracy of remote sensing estimates of ET, which assume a constant rate of stomatal conductance during midday.

  16. Supplementary Material S1. Model uncertainty in transpiration and transpiration fraction

    E-print Network

    Evans, Jason

    Supplementary Material S1. Model uncertainty in transpiration and transpiration fraction The transpiration anomaly estimates in this study are derived from MODIS, J2010, and GLEAM using the ET partitioning accurate than the transpiration as simulated by CLM4 or CABLE. Aside from this fundamental reason

  17. Original article Field comparison of transpiration,

    E-print Network

    Paris-Sud XI, Université de

    Original article Field comparison of transpiration, stomatal conductance and vulnerability potential then ranged from -1.7 to -2.0 MPa. The slightly lower transpiration observed in pedunculate oaks naturelles de la transpiration, de la conductance sto- matique et de la vulnérabilité à la cavitation de

  18. Original article Transpiration and stomatal conductance

    E-print Network

    Paris-Sud XI, Université de

    Original article Transpiration and stomatal conductance of two rain forest species growing (PET). This low transpiration level was explained by incomplete canopy closure and hence a low LAI), that for tropical rain forest species, transpiration may be limited by stomatal clo- sure notwithstanding a high

  19. Optimal Transpiration Boundary Control for Aeroacoustics

    E-print Network

    Heinkenschloss, Matthias

    Optimal Transpiration Boundary Control for Aeroacoustics S. Scott Collis, Kaveh Ghayour transpiration boundary control of aeroacoustic noise in- troduces challenges beyond those encountered in direct of transpiration boundary conditions. Since we allow suction and blowing on the boundary, portions of the boundary

  20. Oxygen isotope signatures of transpired water vapor: the role of isotopic non-steady-state transpiration under natural conditions.

    PubMed

    Dubbert, Maren; Cuntz, Matthias; Piayda, Arndt; Werner, Christiane

    2014-09-01

    The oxygen isotope signature of water is a powerful tracer of water movement from plants to the global scale. However, little is known about the short-term variability of oxygen isotopes leaving the ecosystem via transpiration, as high-frequency measurements are lacking. A laser spectrometer was coupled to a gas-exchange chamber directly estimating branch-level fluxes in order to evaluate the short-term variability of the isotopic composition of transpiration (?E ) and to investigate the role of isotopic non-steady-state transpiration under natural conditions in cork-oak trees (Quercus suber) during distinct Mediterranean seasons. The measured ?(18) O of transpiration (?E ) deviated from isotopic steady state throughout most of the day even when leaf water at the evaporating sites was near isotopic steady state. High agreement was found between estimated and modeled ?E values assuming non-steady-state enrichment of leaf water. Isoforcing, that is, the influence of the transpirational ?(18) O flux on atmospheric values, deviated from steady-state calculations but daily means were similar between steady state and non-steady state. However, strong daytime isoforcing on the atmosphere implies that short-term variations in ?E are likely to have consequences for large-scale applications, for example, partitioning of ecosystem fluxes or satellite-based applications. PMID:24909361

  1. Thermal Transpiration in Microsphere Membranes

    Microsoft Academic Search

    Marcus Young; Yen Lin Han; E. P. Muntz; G. Shiflett; Andrew Ketsdever; Amanda Green

    2003-01-01

    Self-assembled glass microsphere membranes as an alternative transpiration membrane for application in a Knudsen Compressor are discussed. A performance model is constructed and used to compare the performance of glass microsphere membranes to silicon aerogel membranes for this application. An initial experimental Knudsen Compressor stage based on glass microsphere membranes has been designed and experimentally tested. Preliminary performance results show

  2. Transpiration and evaporation from heather Moorland

    NASA Astrophysics Data System (ADS)

    Miranda, A. C.; Jarvis, P. G.; Grace, J.

    1984-03-01

    The energy balance of an upland heath dominated by heather ( Calluna vulgaris) was measured in dry and wet weather. Median values of both transpiration and evaporation rates were ca. 2 mm hr-1. The median Bowen ratio for the dry canopy was 2.0 and for the wet canopy 0.6. On dry days the median value of the saturation deficit was only 3.8 mb and that of the climatological resistance was 30 s m-1. The bulk stomatal resistance increased from ca. 50 s m -2 in the morning to over 290 s m-1 in the afternoon with an overall median value of 110 s m-1. Transpiration from the dry canopy was controlled by a combination of small saturation deficits and large stomatal resistances. The median value of the boundary-layer resistance of the canopy was 22 s m-1 and was low partly because of a large low-level drag coefficient. Saturation deficits on wet days were close to zero and evaporation of intercepted water proceeded at close to the equilibrium rate, being largely limited by the low fluxes of available energy. The water loss from heather was compared with simulated losses from coniferous forest, herbaceous crops and grassland in the same conditions to evaluate the effects of vegetation on water loss from catchments.

  3. Transpiring Cooling of a Scram-Jet Engine Combustion Chamber

    NASA Technical Reports Server (NTRS)

    Choi, Sang H.; Scotti, Stephen J.; Song, Kyo D.; Ries,Heidi

    1997-01-01

    The peak cold-wall heating rate generated in a combustion chamber of a scram-jet engine can exceed 2000 Btu/sq ft sec (approx. 2344 W/sq cm). Therefore, a very effective heat dissipation mechanism is required to sustain such a high heating load. This research focused on the transpiration cooling mechanism that appears to be a promising approach to remove a large amount of heat from the engine wall. The transpiration cooling mechanism has two aspects. First, initial computations suggest that there is a reduction, as much as 75%, in the heat flux incident on the combustion chamber wall due to the transpirant modifying the combustor boundary layer. Secondly, the heat reaching the combustor wall is removed from the structure in a very effective manner by the transpirant. It is the second of these two mechanisms that is investigated experimentally in the subject paper. A transpiration cooling experiment using a radiant heating method, that provided a heat flux as high as 200 Btu/sq ft sec ( approx. 234 W/sq cm) on the surface of a specimen, was performed. The experiment utilized an arc-lamp facility (60-kW radiant power output) to provide a uniform heat flux to a test specimen. For safety reasons, helium gas was used as the transpirant in the experiments. The specimens were 1.9-cm diameter sintered, powdered-stainless-steel tubes of various porosities and a 2.54cm square tube with perforated multi-layered walls. A 15-cm portion of each specimen was heated. The cooling effectivenes and efficiencies by transpiration for each specimen were obtained using the experimental results. During the testing, various test specimens displayed a choking phenomenon in which the transpirant flow was limited as the heat flux was increased. The paper includes a preliminary analysis of the transpiration cooling mechanism and a scaling conversion study that translates the results from helium tests into the case when a hydrogen medium is used.

  4. Does hydraulic lift or nighttime transpiration facilitate nitrogen acquisition?

    Microsoft Academic Search

    Keirith A. Snyder; Jeremy J. James; James H. Richards; Lisa A. Donovan

    2008-01-01

    Water movement from roots to soil at night in the process of hydraulic lift (redistribution) rehydrates the rhizosphere and\\u000a has been proposed to improve plant nutrient acquisition. Another process that has now been found in many plant species is\\u000a nighttime transpiration and this could also affect nutrient relations by influencing supply of mobile nutrients to roots at\\u000a night. The effects

  5. Traumatic injury rates in meatpacking plant workers.

    PubMed

    Culp, Kennith; Brooks, Mary; Rupe, Kerri; Zwerling, Craig

    2008-01-01

    This was a 3-year retrospective cohort study of traumatic injuries in a midwestern pork meatpacking plant. Based on n = 5410 workers, this was a diverse workforce: Caucasian (56.6%), Hispanic (38.9%), African American (2.7%), Asian (1.1%) and Native American (0.8%). There were n = 1655 employees with traumatic injuries during this period. At 6 months of employment, the probability of injury was 33% in the harvest workers who were responsible for slaughter operations. The overall incidence injury rate was 22.76 per 100 full-time employees per year. Women experienced a higher incidence for injury than men. The risk ratio (RR) for traumatic injury was significantly lower in Hispanic workers compared to Caucasians (RR = 0.54, 95% CI = 0.49-0.60) and nonsignificantly higher in African American and Native American workers after adjusting for age, gender, work section assignment, and experience (RR = 1.33, 95% CI = 1.21-1.47). These findings suggest that either Hispanics are very safe employees or they underreport injuries. We make the case for the latter in the discussion. PMID:19042688

  6. Comparative photosynthesis, growth and transpiration of two species of Atriplex

    Microsoft Academic Search

    R. O. Slatyer

    1970-01-01

    Throughout a period of 23 days, during which the photosynthesis, growth and transpiration of two species of Atriplex were compared, A. spongiosa, a “C4” species (first products of photosynthesis = 4-C dicarboxylic acids), maintained net rates of leaf photosynthesis as high as, or higher than, those of A. hastata, a “C3” species (photosynthesis exhibiting the Calvin-type characteristics).

  7. Accommodation between transpiring vegetation and the convective boundary layer

    Microsoft Academic Search

    J. L. Monteith

    1995-01-01

    A simple scheme is developed to describe how vegetation and the convective boundary layer (CBL) interact during daylight in terms of water and sensible heat exchange. The response of vegetation to a prescribed atmospheric state is defined by a quadratic equation obtained by combining the Penman-Monteith equation with a new relation between surface conductance and transpiration rate based on laboratory

  8. Transpiration-induced changes in the photosynthetic capacity of leaves

    Microsoft Academic Search

    Thomas D. Sharkey

    1984-01-01

    High transpiration rates were found to affect the photosynthetic capacity of Xanthium strumarium L. leaves in a manner analagous to that of low soil water potential. The effect was also looked for and found in Gossypium hirsutum L., Agathis robusta (C. Moore ex Muell.) Bailey, Eucalyptus microcarpa Maiden, Larrea divaricata Cav., the wilty flacca tomato mutant (Lycopersicon esculentum (L.) Mill.)

  9. Stomatal conductance and transpirational responses of field-grown cotton to ozone

    SciTech Connect

    Temple, P.J.

    1986-01-01

    Stomatal conductance and transpiration were measured on normally-irrigated and water-stressed field-grown cotton (Grossypium hirsutum) exposed throughout the growing season to a gradient of ozone (O/sub 3/) concentrations. Environmental conditions during the growing season strongly affected stomatal responses and yield redutions due to O/sub 3/ exposure. Maximum stomatal conductance and transpiration decreased with increased O/sub 3/ concentration both in NI and WS treatments. Reductions in conductance and transpiration in O/sub 3/-stressed plants were attributed to inhibition of photosynthesis by O/sub 3/, leading to accumulation of CO/sub 2/ in intercellular spaces.

  10. Decreased transpiration in poplar trees exposed to 2,4,6-trinitrotoluene

    SciTech Connect

    Thompson, P.L. [Seattle Univ., WA (United States). Dept. of Civil and Environmental Engineering; Ramer, L.A.; Guffey, A.P.; Schnoor, J.L. [Univ. of Iowa, Iowa City, IA (United States). Dept. of Civil and Environmental Engineering

    1998-01-01

    The improper handling of the toxic compound 2,4,6-trinitrotoluene (TNT) has led to the contamination of soil and groundwater, and the uptake of TNT by a variety of plants has been established. This article discusses the effects of various concentrations of the explosive 2,4,6-trinitrotoluene (TNT) on the transpiration of hybrid poplar trees growing in hydroponic media. Transpiration was measured daily by gravimetric means. The rapid removal of TNT from hydroponic solutions was a result of plant uptake and required a daily dosage of TNT to ensure a relatively constant exposure over time. Transpiration decreased with increasing TNT concentrations {ge}5 mg/L. Decreases in transpiration were accompanied by leaf chlorosis and abscission. A comparison between a laboratory study and a pilot-scale experiment showed good scale-up potential.

  11. Modeling the uptake and transpiration of TCE using phreatophytic trees. Master`s Thesis

    SciTech Connect

    Wise, D.P.

    1997-12-01

    Phytoremediation is a recent addition to the numerous methods used today to remediate ground water contaminants. It is proving more effective and efficient compared to existing remediation techniques. The use of phreatophytes, or water seeking trees, has great potential for phytoremediation. These trees are fast growing, long lived, grow their roots down to the ground water table, transpire large amounts of water, and are proven to actively remove contaminants from the soil horizon. The purpose of this research is to develop quantitative concepts for understanding the dynamics of TCE uptake and transpiration by phreatophytic trees over a short rotation woody crop time frame. This will he done by constructing a system dynamics model of this process and running it over a wide range of conditions. This research will offer managers a tool to simulate long-term uptake and transpiration of TCE at potential sites. The results of this study indicate that TCE is actively removed from the soil horizon by phreatophytic trees and a significant proportion of this TCE is then transpired. Changes in soil horizon parameters, xylem flow rates, and variables in the uptake equation greatly influence TCE uptake rates as well as transpiration. Also, parameters used in equations representing flows in and out of the leaf greatly influence transpiration. Better understanding of these processes is essential for managers to accurately predict the amount of TCE removed and transpired during potential phytoremediation projects.

  12. Groundwater Constraints on Simulated Transpiration Variability over Southeastern Australian Forests

    E-print Network

    Evans, Jason

    Groundwater Constraints on Simulated Transpiration Variability over Southeastern Australian Forests to explore the impact of rainfall variability on transpiration over drought-vulnerable regions, there is a low correlation between rainfall variability and the response of transpiration to this variability

  13. Rate of Contamination Removal of Two Phyto-remediation Sites at the DOE Portsmouth Gaseous Diffusion Plant

    SciTech Connect

    Lewis, A.C.; Baird, D.R. [CDM Federal Services, P.O. Box 789, Piketon, OH 45661 (United States)

    2006-07-01

    This paper describes applications of phyto-remediation at the Portsmouth Gaseous Diffusion Plant (PORTS), a Department of Energy (DOE) Facility that enriched uranium from the early 1950's until 2000. Phyto-remediation has been implemented to assist in the removal of TCE (trichloroethylene) in the groundwater at two locations at the PORTS facility: the X-740 area and the X-749/X-120 area. Phyto-remediation technology is based on the ability of certain plants species (in this case hybrid poplar trees) and their associated rhizo-spheric microorganisms to remove, degrade, or contain chemical contaminants located in the soil, sediment, surface water, groundwater, and possibly even the atmosphere. Phyto-remediation technology is a promising clean-up solution for a wide variety of pollutants and sites. Mature trees, such as the hybrid poplar, can consume up to 3,000 gallons of groundwater per acre per day. Organic compounds are captured in the trees' root systems. These organic compounds are degraded by ultraviolet light as they are transpired along with the water vapor through the leaves of the trees. The phyto-remediation system at the X-740 area encompasses 766 one-year old hybrid poplar trees (Populus nigra x nigra, Populus nigra x maximowiczii, and Populus deltoides x nigra) that were planted 10 feet apart in rows 10 feet to 20 feet apart, over an area of 2.6 acres. The system was installed to manage the VOC contaminant plume. At the X749/X-120 area, a phyto-remediation system of 2,640 hybrid poplar trees (Populus nigra x maximowiczii) was planted in seven areas/zones to manage the VOC contaminant plume. The objectives of these systems are to remove contamination from the groundwater and to prevent further migration of contaminants. The goal of these remediation procedures is to achieve completely mature and functional phyto-remediation systems within two years of the initial planting of the hybrid poplar trees at each planting location. There is a direct relationship between plant transpiration, soil moisture, and groundwater flow in a phyto-remediation system. The existing monitoring program was expanded in 2004 in order to evaluate the interactions among these processes. The purpose of this monitoring program was to determine the rate of contaminant removal and to more accurately predict the amount of time needed to remediate the contaminated groundwater. Initial planting occurred in 1999 at the X-740 area, with additional replanting in 2001 and 2002. In 2003, coring of selected trees and chemical analyses illustrated the presence of TCE; however, little impact was observed in groundwater levels, analytical monitoring, and periodic tree diameter monitoring at the X-740 area. To provide better understanding of how these phyto-remediation systems work, a portable weather station was installed at the X-740 area to provide data for estimating transpiration and two different systems for measuring sap flow and sap velocity were outfitted to numerous trees. After evaluating and refining the groundwater flow and contaminant transport models, the data gathered by these two inventive methods can be used to establish a rate of contaminant removal and to better predict the time required in order to meet remediation goals for the phyto-remediation systems located at the PORTS site. (authors)

  14. Material Response of One-Dimensional, Steady-State Transpiration Cooling in Radiative and Convective Environments

    NASA Technical Reports Server (NTRS)

    Kubota, Hirotoshi

    1975-01-01

    A simplified analytical solution for thermal response of a transpiration-cooled porous heat-shield material in an intense radiative-convective heating environment is presented. Essential features of this approach are "two-flux method" for radiative transfer process and "two-temperature" assumption for solid and gas temperatures. Incident radiative-convective heatings are specified as boundary conditions. Sample results are shown using porous silica with CO2 transpiration and some parameters quantitatively show the effect on this transpiration cooling system. Summarized maps for mass injection rate, porosity and blowing correction factor for radiation are obtained in order to realize such a cooling system.

  15. Transpiration Cooling Of Hypersonic Blunt Body

    NASA Technical Reports Server (NTRS)

    Henline, William D.

    1991-01-01

    Results on analytical approximation and numerical simulation compared. Report presents theoretical study of degree to which transpiration blocks heating of blunt, axisymmetric body by use of injected air. Transpiration cooling proposed to reduce operating temperatures on nose cones of proposed hypersonic aerospace vehicles. Analyses important in design of thermal protection for such vehicles.

  16. Auxin metabolism rates and implications for plant development

    PubMed Central

    Kramer, Eric M.; Ackelsberg, Ethan M.

    2015-01-01

    Studies of auxin metabolism rarely express their results as a metabolic rate, although the data obtained would often permit such a calculation to be made. We analyze data from 31 previously published papers to quantify the rates of auxin biosynthesis, conjugation, conjugate hydrolysis, and catabolism in seed plants. Most metabolic pathways have rates in the range 10 nM/h–1 ?M/h, with the exception of auxin conjugation, which has rates as high as ~100 ?M/h. The high rates of conjugation suggest that auxin metabolic sinks may be very small, perhaps as small as a single cell. By contrast, the relatively low rate of auxin biosynthesis requires plants to conserve and recycle auxin during long-distance transport. The consequences for plant development are discussed.

  17. PLANT CULTURAL SYSTEM FOR MONITORING EVAPOTRANSPIRATION AND PHYSIOLOGICAL RESPONSES UNDER FIELD CONDITIONS

    EPA Science Inventory

    A plant culture system incorporating the water-table root-screen method for controlling plant water status was adapted for use in open-top field exposure chambers for studying the effects of drought stress on physiological responses. The daily transpiration rates of the plants we...

  18. SK30 total energy plant rated at 73% efficiency

    SciTech Connect

    de Biasi, V. (ed.)

    1980-07-01

    The City of Hague in Holland is building a combined cycle plant. The plant will be powered by two Rolls-Royce SK30 gas turbine generators site rated at 25,000 kW each, two unfired Stork waste heat recovery boilers, and a Delaval Stork steam turbine rated at 26,000 kW. On its own, without district heating, the combined cycle plant is rated for 77,000 kW output at around 44% efficiency. Heat output of the combined cycle plant is used to provide thermal power for district heating. In the maximum output mode, there is some drop in electric power output (around 70,000 kW) but this is accompanied by 60,000 kW thermal power output for a net plant efficiency of close to 74% overall. (MCW)

  19. Changes in the photosynthetic characteristics of Plantago major plants caused by soil drought stress

    Microsoft Academic Search

    V. Mudrik; A. Kosobrukhov; I. Knyazeva; T. Pigulevskaya

    2003-01-01

    Changes in net photosynthetic rate (PN), stomatal conductance (gs), intercellular CO2 concentrations (Ci), transpiration rate (E) and water use efficiency (WUE) were measured in Plantago major L. plants grown under sufficient soil water supply or under soil water stress conditions. The plants had high PN in a wide range of soil water potential and temperature regimes. Soil water had little

  20. Plant respirometer enables high resolution of oxygen consumption rates

    NASA Technical Reports Server (NTRS)

    Foster, D. L.

    1966-01-01

    Plant respirometer permits high resolution of relatively small changes in the rate of oxygen consumed by plant organisms undergoing oxidative metabolism in a nonphotosynthetic state. The two stage supply and monitoring system operates by a differential pressure transducer and provides a calibrated output by digital or analog signals.

  1. Mostly Plants. Individualized Biology Activities on: I. Investigating Bread Mold; II. Transpiration; III. Botany Project; IV. Collecting/Preserving/Identifying Leaves; [and] V. Student Science Laboratory Write-Ups.

    ERIC Educational Resources Information Center

    Gibson, Paul R.

    Individualized biology activities for secondary students are presented in this teaching guide. The guide is divided into five sections: (1) investigating bread mold; (2) investigating transpiration; (3) completing a botany project; (4) collecting, preserving, and identifying leaves; and (5) writing up science laboratory investigations. The…

  2. Transpiration characteristics of forests and shrubland under land cover change within the large caldera of Mt. Aso, Japan

    NASA Astrophysics Data System (ADS)

    Miyazawa, Y.; Inoue, A.; Maruyama, A.

    2013-12-01

    Grassland within a caldera of Mt. Aso has been maintained for fertilizer production from grasses and cattle feeding. Due to the changes in the agricultural and social structure since 1950's, a large part of the grassland was converted to plantations or abandoned to shrublands. Because vegetations of different plant functional types differ in evapotranspiration; ET, a research project was launched to examine the effects of the ongoing land use change on the ET within the caldera, and consequently affect the surface and groundwater discharge of the region. As the part of the project, transpiration rate; E of the major 3 forest types were investigated using sap flow measurements. Based on the measured data, stomatal conductance; Gs was inversely calculated and its response to the environmental factors was modeled using Jarvis-type equation in order to estimate ET of a given part of the caldera based on the plant functional type and the weather data. The selected forests were conifer plantation, deciduous broadleaved plantation and shrubland, which were installed with sap flow sensors to calculate stand-level transpiration rate. Sap flux; Js did not show clear differences among sites despite the large differences in sapwood area. In early summer solar radiation was limited to low levels due to frequent rainfall events and therefore, Js was the function of solar radiation rather than other environmental factors, such as vapor pressure deficit and soil water content. Gs was well regressed with the vapor pressure deficit and solar radiation. The estimated E based on Gs model and the weather data was 0.3-1.2 mm day-1 for each site and was comparable to the E of grassland in other study sites. Results suggested that transpiration rate in growing was not different between vegetations but its annual value are thought to differ due to the different phenology.

  3. Effects of Typha latifolia transpiration and harvesting on nitrate concentrations in surface water of wetland microcosms

    Microsoft Academic Search

    Jay Martin; Elizabeth Hofherr; Martin F. Quigley

    2003-01-01

    Abtract  This experiment tested the hypothesis that the movement of water into the soil due to macrophyte transpiration stimulates\\u000a nitrate removal from wetlands. The short-term impacts of biomass harvesting upon the ability of wetlands to reduce nitrate\\u000a concentrations were also investigated. Different amounts of biomass were harvested fromTypha latifolia specimens to create three treatments of varying transpiration rates. Harvesting and the

  4. Effect of plants on sunspace passive solar heating

    SciTech Connect

    Best, E.D.; McFarland, R.D.

    1985-01-01

    The effect of plants on sunspace thermal performance is investigated, based on experiments done in Los Alamos using two test rooms with attached sunspaces, which were essentially identical except for the presence of plants in one. Performance is related to plant transpiration, evaporation from the soil, condensation on the glazing and the absorbtance of solar energy by the lightweight leaves. Performance effects have been quantified by measurements of auxiliary heat consumption in the test rooms and analyzed by means of energy balance calculations. A method for estimating the transpiration rate is presented.

  5. Transpiration Regulation of silver firs during and after severe droughts in relation to soil properties

    NASA Astrophysics Data System (ADS)

    Chanzy, A.; Nourtier, M.

    2011-12-01

    Silver fir is declining and dying in the Mediterranean area, at its southern margin where climate is expected to become warmer and drier. At regional scale, silver fir death seems to be located on dry areas while it depends on soil water availability at forest stand scale. To understand silver firs vulnerability to drought, factors involved in their transpiration regulation were studied. An experiment was carried out on Mont Ventoux (in Provence region in south of France) which is a karstic area. Soil properties were characterised by electric resistivity tomography for estimating soil water storage capacity through the determination of soil depth and stones content. Transpiration, predawn leaf water potential dynamic and crown surface temperature were measured on trees during three years. Vulnerability curves to embolism of coarse roots and branches were established. Finally, tree growth rate history was analysed using tree ring width analysis. The experiment covered three very different climatic years. 2008 was a wet year, whereas a severe drought occurred in summer 2009 and in less extent in 2010. Soils were well watered during winters thanks to exceptional snow falls. In the context of the experiment, silver firs strongly regulate their transpiration. Transpiration/potential transpiration ratio is mostly far below 1. The decrease in transpiration rate during drying periods were the quickest on soil having small and large water storage capacity whereas on the intermediate cases, the decrease was more gradual. Moreover, the water stress intensity, derived from predawn leaf water potential, was the largest on soil having large water storage capacity. After the 2009 severe drought, transpiration rate remains much low after fall rainfalls. The transpiration drop persisted after the winter while soils were well watered. Sap flow radial distributions have suggested that the deeps roots were not reactivated after the drought. Tring ring width analysis showed that the impact of a severe drought as that of 1976 may impact the tree physiology over very long periods (>10 years). The aboveground/belowground development during the juvenile period appeared as a key to understand the tree regulation to water stress. Long term regulation mechanisms based on carbon availability allocation should be accounted for to represent the transpiration regulation. Our observations have shown that transpiration modelling schemes, based on energy balance and stomatal regulation only, are not appropriate to represent silver transpiration rate during and after drought. Some additional regulation processes have been proposed.

  6. Plant acclimation to elevated CO? affects important plant functional traits, and concomitantly reduces plant colonization rates by an herbivorous insect.

    PubMed

    Klaiber, Jeannine; Najar-Rodriguez, Adriana J; Piskorski, Rafal; Dorn, Silvia

    2013-01-01

    Plants growing under elevated CO? concentration may acclimatize to this environmental change by modification of chemical, physiological, and/or morphological traits. As a consequence, not only plant functioning but also plant-insect interactions might be altered, with important consequences particularly for agricultural systems. Whereas most studies have focused on the plant acclimation effects of elevated CO? with regard to crop growth and productivity, acclimation effects on the behavioral response of insects associated with these plants have been largely neglected. In this study, we used a model system comprised of Brussels sprout Brassica oleraceae var. gemmifera and a specialized herbivorous insect, the cabbage aphid Brevicoryne brassicae, to test for the effects of various periods of exposure to an elevated (2× ambient) CO? concentration on key plant functional traits and on host plant location behavior by the insect, assessed as plant colonization rates. Elevated CO? had no measurable effect on colonization rates or total plant volatile emissions after a 2-week exposure, but it led to 15 and 26 % reductions in plant colonization rates after 6- and 10-week exposures, respectively. This reduction in plant colonization was associated with significant decreases in leaf stomatal conductance and plant volatile emission. Terpene emission, in particular, exhibited a great reduction after the 10-week exposure to elevated CO?. Our results provide empirical evidence that plants might acclimatize to a future increase in CO?, and that these acclimation responses might affect host plant choice and colonization behavior by herbivorous insects, which might be advantageous from the plant's perspective. PMID:22968910

  7. Transpiration And Regenerative Cooling Of Rocket Engine

    NASA Technical Reports Server (NTRS)

    Obrien, Charles J.

    1989-01-01

    Transpiration cooling extends limits of performance. Addition of transpiration cooling to regeneratively-cooled rocket-engine combustion chamber proposed. Modification improves performance of engine by allowing use of higher chamber pressure. Throat section of combustion-chamber wall cooled by transpiration, while chamber and nozzle sections cooled by fluid flowing in closed channels. Concept applicable to advanced, high-performance terrestrial engines or some kinds of industrial combustion chambers. With proper design, cooling scheme makes possible to achieve higher chamber pressure and higher overall performance in smaller engine.

  8. [Greenhouse tomato transpiration and its affecting factors: correlation analysis and model simulation].

    PubMed

    Yao, Yong-Zhe; Li, Jian-Ming; Zhang, Rong; Sun, San-Jie; Chen, Kai-Li

    2012-07-01

    A pot experiment was conducted to study the correlations between the daily transpiration of greenhouse tomato and the related affecting factors such as total leaf area per plant, soil relative moisture content, air temperature, relative humidity, and solar radiation under different treatments of supplementary irrigation. A regression model for the daily transpiration of greenhouse tomato was established. There existed significant linear correlations between the daily transpiration and the test affecting factors, and the affecting factors had complicated mutual effects. Soil relative moisture content was the main decision factor of the transpiration, with the decision coefficient being 27.4%, and daily minimum relative humidity was the main limiting factor, with the decision coefficient being -119.7%. The square value of the regression coefficient (R2) between the predicted and measured tomato daily transpiration was 0.81, root mean squared error (RMSE) was 68.52 g, and relative prediction error (RE) was 19.4%, suggesting that the regression model established by using the main affecting factors selected through path analysis could better simulate the daily transpiration of greenhouse tomato. PMID:23173461

  9. Transpirational demand affects aquaporin expression in poplar roots

    PubMed Central

    Hacke, Uwe G.

    2013-01-01

    Isohydric plants tend to maintain a water potential homeostasis primarily by controlling water loss via stomatal conductance. However, there is accumulating evidence that plants can also modulate water uptake in a dynamic manner. The dynamics of water uptake are influenced by aquaporin-mediated changes in root hydraulics. Most studies in this area have been conducted on herbaceous plants, and less is known about responses of woody plants. Here a study was conducted to determine how roots of hybrid poplar plants (Populus trichocarpa×deltoides) respond to a step change in transpirational demand. The main objective was to measure the expression of selected aquaporin genes and to assess how transcriptional responses correspond to changes in root water flow (Q R) and other parameters of water relations. A subset of plants was grown in shade and was subsequently exposed to a 5-fold increase in light level. Another group of plants was grown at ~95% relative humidity (RH) and was then subjected to lower RH while the light level remained unchanged. Both plant groups experienced a transient drop in stem water potentials. At 28h after the increase in transpirational demand, water potentials recovered. This recovery was associated with changes in the expression of PIP1 and PIP2 subfamily genes and an increase in Q R. Stomata of plants growing at high RH were larger and showed incomplete closure after application of abscisic acid. Since stomatal conductance remained high and unchanged in these plants, it is suggested that the recovery in water potential in these plants was largely driven by the increase in Q R. PMID:23599275

  10. Transpiring Interfaces: Turning Transparency on Its Head

    E-print Network

    Indiana University

    Transpiring Interfaces: Turning Transparency on Its Head Hamid R. Ekbia Abstract The contrastive-STAR (Transparent State-space search Architecture), which is also described as a transparent interface to state-space

  11. A Phytotoxicity Test Using Transpiration of Willows

    Microsoft Academic Search

    S. Trapp; K. C. Zambrano; K. O. Kusk; U. Karlson

    2000-01-01

    A short-term acute toxicity assay for willow trees growing in contaminated solution or in polluted soil was developed and\\u000a tested. The test apparatus consists of an Erlenmeyer flask with a prerooted tree cutting growing in it. Growth and reduction\\u000a of transpiration are used to determine toxicity. Transpiration is closely related to photosynthesis and growth, but is easier\\u000a and faster to

  12. Transpiration by trees under seasonal water logging and drought in monsoon central Cambodia

    NASA Astrophysics Data System (ADS)

    Miyazawa, Y.; Tateishi, M.; Kajisa, T.; Ma, V.; Heng, S.; Kumagai, T.; Mizoue, N.

    2012-04-01

    Cambodia is situated in the center of Indochina Peninsula and experiences severe drought for 5 months of dry season and subsequent rainy season. Around the Tonlesap Lake where both natural and secondary forests exist without intensive destruction by human activity, forest hydrology is characterized by seasonal water logging in mid rainy season. Tree- and stand-scale transpiration is thought to be influenced by the changing soil water conditions and trees' site-specific adaptation to the environment, but less is measured about transpiration and leaf ecophysiological traits in this region. The objectives of this study is to reveal the ecophysiology of the two native (Dipterocarpus obtusifolius and Shorea roxburghii) and two exotic species (Acacia auriculiformis and Eucalyptus camaldulensis) and to detect the effects of soil water conditions on day to week scale transpiration in mid rainy and dry season. Seasonal leaf-level photosynthesis measurements suggested that photosynthetic capacity (Vcmax25) showed no clear seasonal change in each species without clear interspecific variation. Two native species had stomatal control in response to the environment different from previous studies and showed stomatal conductance higher than most woody species in other seasonal tropical forests, suggesting the species- and site-specific adaptation to the easy access to the ground water. Sap flow rate per leaf area was expressed in two parameters: measured transpiration rate based on the continuous sap flow measurements (Esap) and modeled transpiration rate (Emod) using a multilayer model based on the measured data of atmospheric environments, radiation and the leaf ecophysiological traits. Esap was lower in rainy season than those in dry season, with short but pronounced drop near the end of the dry season, although Emod was higher in rainy season than in dry season. In dry season, Emod well fit the diurnal and day to day trend of Esap, suggesting that soil drought did not limit transpiration. On the other hand, in rainy season, Emod overestimated Esap under high light intensities but not at low Emod conditions, suggesting that leaf water demand exceeded the water supply capacity, possibly due to the water logging effects on root activity. This study provided us new insights into the site specific transpiration patterns in this region, and the usefulness of the comparison between modeled and measured transpiration rate to detect the environmental and biological influence on transpiration for successful model prediction of forest transpiration at large time and spatial scales.

  13. Separating foliar physiology from morphology reveals the relative roles of vertically structured transpiration factors within red maple crowns and limitations of larger scale models

    PubMed Central

    Bauerle, William L.; Bowden, Joseph D.

    2011-01-01

    A spatially explicit mechanistic model, MAESTRA, was used to separate key parameters affecting transpiration to provide insights into the most influential parameters for accurate predictions of within-crown and within-canopy transpiration. Once validated among Acer rubrum L. genotypes, model responses to different parameterization scenarios were scaled up to stand transpiration (expressed per unit leaf area) to assess how transpiration might be affected by the spatial distribution of foliage properties. For example, when physiological differences were accounted for, differences in leaf width among A. rubrum L. genotypes resulted in a 25% difference in transpiration. An in silico within-canopy sensitivity analysis was conducted over the range of genotype parameter variation observed and under different climate forcing conditions. The analysis revealed that seven of 16 leaf traits had a ?5% impact on transpiration predictions. Under sparse foliage conditions, comparisons of the present findings with previous studies were in agreement that parameters such as the maximum Rubisco-limited rate of photosynthesis can explain ?20% of the variability in predicted transpiration. However, the spatial analysis shows how such parameters can decrease or change in importance below the uppermost canopy layer. Alternatively, model sensitivity to leaf width and minimum stomatal conductance was continuous along a vertical canopy depth profile. Foremost, transpiration sensitivity to an observed range of morphological and physiological parameters is examined and the spatial sensitivity of transpiration model predictions to vertical variations in microclimate and foliage density is identified to reduce the uncertainty of current transpiration predictions. PMID:21617246

  14. Quantitative Trait Locus (QTL) Mapping of Transpiration Efficiency Related to Pre-flower Drought Tolerance in Sorghum [Sorghum bicolor (L.) Moench

    E-print Network

    Heraganahally Kapanigowda, Mohankumar

    2012-07-16

    of the study was to estimate the genetic variation and genetic basis for transpiration efficiency A:E (CO2 assimilation rate (A) divided by transpiration rate (E)) trait and its relationship to WUE related to pre-flower drought tolerance in recombinant inbred...

  15. A Remote Sensing Study of the NDVI– T s Relationship and the Transpiration from Sparse Vegetation in the Sahel Based on High-Resolution Satellite Data

    Microsoft Academic Search

    E. Boegh; H. Soegaard; N. Hanan; P. Kabat; L. Lesch

    1999-01-01

    This article proposes a new approach for estimation of the transpiration rate in sparse canopies. The method relies on a combination of techniques; some of which having a successful background of solid experimental and theoretical justification, while others having only recently been introduced as promising tools for the extraction of environmental information from satellite data. The transpiration rate (?Ev) is

  16. PATHWAYS, MECHANISMS, AND RATES OF POLYPLOID FORMATION IN FLOWERING PLANTS

    Microsoft Academic Search

    Justin Ramsey; Douglas W. Schemske

    1998-01-01

    Polyploidy is widely acknowledged as a major mechanism of adaptation and speciation in plants. The stages in polyploid evolution include frequent fertility bottlenecks and infrequent events such as gametic nonreduction and interspecific hybridization, yet little is known about how these and other factors influence over- all rates of polyploid formation. Here we review the literature regarding polyploid origins, and quantify

  17. Improvements in plant growth rate using underwater discharge

    NASA Astrophysics Data System (ADS)

    Takaki, K.; Takahata, J.; Watanabe, S.; Satta, N.; Yamada, O.; Fujio, T.; Sasaki, Y.

    2013-03-01

    The drainage water from plant pots was irradiated by plasma and then recycled to irrigate plants for improving the growth rate by supplying nutrients to plants and inactivating the bacteria in the bed-soil. Brassica rapa var. perviridis (Chinese cabbage; Brassica campestris) plants were cultivated in pots filled with artificial soil, which included the use of chicken droppings as a fertiliser. The water was recycled once per day from a drainage water pool and added to the bed-soil in the pots. A magnetic compression type pulsed power generator was used to produce underwater discharge with repetition rate of 250 pps. The plasma irradiation times were set as 10 and 20 minutes per day over 28 days of cultivation. The experimental results showed that the growth rate increased significantly with plasma irradiation into the drainage water. The growth rate increased with the plasma irradiation time. The nitrogen concentration of the leaves increased as a result of plasma irradiation based on chlorophyll content analysis. The bacteria in the drainage water were inactivated by the plasma irradiation.

  18. HYDROLOGICAL IMPACTS OF WOODY PLANT ENCROACHMENT IN ARID AND SEMIARID GRASSLANDS

    EPA Science Inventory

    Woody plants may be able to access deeper groundwater for year-round transpiration and thus consume more water than grasses, affecting recharge, soil moisture and runoff. Amount of water available to plants from precipitation is determined in part by nfiltration rates into...

  19. Experimental studies of transpiration cooling with shock interaction in hypersonic flow, part B

    NASA Technical Reports Server (NTRS)

    Holden, Michael S.

    1994-01-01

    This report describes the result of experimental studies conducted to examine the effects of the impingement of an oblique shock on the flowfield and surface characteristics of a transpiration-cooled wall in turbulent hypersonic flow. The principal objective of this work was to determine whether the interaction between the oblique shock and the low-momentum region of the transpiration-cooled boundary layer created a highly distorted flowfield and resulted in a significant reduction in the cooling effectiveness of the transpiration-cooled surface. As a part of this program, we also sought to determine the effectiveness of transpiration cooling with nitrogen and helium injectants for a wide range of blowing rates under constant-pressure conditions in the absence of shock interaction. This experimental program was conducted in the Calspan 48-Inch Shock Tunnel at nominal Mach numbers of 6 and 8, for a Reynolds number of 7.5 x 10(exp 6). For these test conditions, we obtained fully turbulent boundary layers upstream of the interaction regions over the transpiration-cooled segment of the flat plate. The experimental program was conducted in two phases. In the first phase, we examined the effects of mass-addition level and coolant properties on the cooling effectiveness of transpiration-cooled surfaces in the absence of shock interaction. In the second phase of the program, we examined the effects of oblique shock impingement on the flowfield and surface characteristics of a transpiration-cooled surface. The studies were conducted for a range of shock strengths with nitrogen and helium coolants to examine how the distribution of heat transfer and pressure and the characteristics of the flowfield in the interaction region varied with shock strength and the level of mass addition from the transpiration-cooled section of the model. The effects of the distribution of the blowing rate along the interaction regions were also examined for a range of blowing rates through the transpiration-cooled panels. The regions of shockwave/boundary layer interaction examined in these studies were induced by oblique shocks generated with a sharp, flat plate, inclined to the freestream at angles of 5 degrees, 7.5 degrees, and 10 degrees. It was found that, in the absence of an incident shock, transpiration cooling was a very effective method for reducing both the heat transfer and the skin friction loads on the surface. The helium coolant was found to be significantly more effective than nitrogen, because of its low molecular weight and high specific heat. The studies of shock-wave/transpiration-cooled surface interaction demonstrated that the interaction region between the incident shock and the low-momentum transpiration-cooled boundary layer did not result in a significant increase in the size of attached or separated interaction regions, and did not result in significant flowfield distortions above the interaction region. The increase in heating downstream of the shock-impingement point could easily be reduced to the values without shock impingement by a relatively small increase in the transpiration cooling in this region. Surprisingly, this increase in cooling rate did not result in a significant increase in size of the region ahead of the incident shock or create a significantly enlarged interaction region with a resultant increase in the distortion level in the inviscid flow. Thus, transpiration cooling appears to be a very effective technique to cool the internal surfaces of scramjet engines, where shocks in the engine would induce large local increases in wall heating and create viscous/inviscid interactions that could significantly disturb the smooth flow through the combustor. However, if hydrogen is used as the coolant, burning upstream of shock impingement might result in localized hot spots. Clearly, further research is needed in this area.

  20. Nutrient and water addition effects on day- and night-time conductance and transpiration in a C 3 desert annual

    Microsoft Academic Search

    Fulco Ludwig; Rebecca A. Jewitt; Lisa A Donovan

    2006-01-01

    Recent research has shown that many C3 plant species have significant stomatal opening and transpire water at night even in desert habitats. Day-time stomatal regulation is expected to maximize carbon gain and prevent runaway cavitation, but little is known about the effect of soil resource availability on night-time stomatal conductance (g) and transpiration (E). Water (low and high) and nutrients

  1. Responses of canopy transpiration and canopy conductance of peach (Prunus persica) trees to alternate partial root zone drip irrigation

    NASA Astrophysics Data System (ADS)

    Gong, Daozhi; Kang, Shaozhong; Zhang, Jianhua

    2005-08-01

    We investigated canopy transpiration and canopy conductance of peach trees under three irrigation patterns: fixed 1/2 partial root zone drip irrigation (FPRDI), alternate 1/2 partial root zone drip irrigation (APRDI) and full root zone drip irrigation (FDI). Canopy transpiration was measured using heat pulse sensors, and canopy conductance was calculated using the Jarvis model and the inversion of the Penman-Monteith equation. Results showed that the transpiration rate and canopy conductance in FPRDI and APRDI were smaller than those in FDI. More significantly, the total irrigation amount was greatly reduced, by 34.7% and 39.6%, respectively for APRDI and FPRDI in the PRDI (partial root zone drip irrigation) treatment period. The daily transpiration was linearly related to the reference evapotranspiration in the three treatments, but daily transpiration of FDI is more than that of APRDI and FPRDI under the same evaporation demand, suggesting a restriction of transpiration water loss in the APRDI and FPRDI trees. FDI needed a higher soil water content to carry the same amount of transpiration as the APRDI and FPRDI trees, suggesting the hydraulic conductance of roots of APRDI and FPRDI trees was enhanced, and the roots had a greater water uptake than in FDI when the average soil water content in the root zone was the same. By a comparison between the transpiration rates predicted by the Penman-Monteith equation and the measured canopy transpiration rates for 60 days during the experimental period, an excellent correlation along the 1:1 line was found for all the treatments (R2 > 0.80), proving the reliability of the methodology.

  2. Transpiration Driven Hydrologic Transport in vegetated shallow water environments: Implications on Diel and Seasonal Soil Biogeochemical Processes and System Management

    NASA Astrophysics Data System (ADS)

    Bachand, P.; Bachand, S. M.; Fleck, J.; Anderson, F.

    2011-12-01

    Hydrology arguably plays the most important role in biogeochemical cycling of mercury in wetlands and other shallow aquatic systems. CFSTR, PFR and non-ideal reactor models are oftentimes currently used to hydrologically assess these systems and to account for the fate, transport and cycling of constituents of concern (COC) with systems assumed to be non-leaky and with diffusion dominating soil transport. Yet a number of results in the literature imply transpiration drives soil transport: transpiration into the root zone is in the range of 50 - 75% of ET seasonally; gaseous emissions from aquatic systems show a diel pattern that tracks diel ET patterns; in long detention time aquatic systems ET is the largest sink for applied surface waters; and non-reactive tracers when applied to surface waters can find themselves in the root zone and within plants. All these findings strongly suggest transpiration driven infiltration into the root zone, is a significant hydrologic pathway for constituents and is an important transport mechanism. This paper examines the annual water budget for four shallow aquatic land uses in the Yolo Bypass, California: rice, wild rice, fallowed fields and wetlands. Results indicate that differences in hydrology between the fields, particularly the temporal nature of transpiration, play a significant role in mercury transformations and transport. During the irrigation period, fallowed fields discharged 6 cm of surface water (15% applied water), rice fields 31 - 43 cm (27 - 31% applied water), and wild rice fields 16 - 39 cm (15 - 31% applied water). Evapotranspiration rates were in the range of 120 - 130 cm/y for all land uses (i.e. rice, wild rice, fallowed fields and seasonal wetlands) except for the permanent wetland which was about 1/3 higher at about 170 cm/y. During the summer, approximately 50% of the applied surface water was drawn into the root zone to meet transpiration demands. Based upon results from our water budget and utilizing modified Peclet No. calculations, we quantified the relative importance of upward diffusion from the sediments and downward advection from transpiration as hydrologic transport mechanisms in the root zone. Transpiration driven infiltration moves water past the diffusive zone within 1 - 2 days in this system during the summer months. With the waning seasons, evapotranspiration diminishes until by winter diffusion dominates throughout the entire root zone. This model has great implications on the analyses of soil biogeochemical process in the root zone of shallow aquatic systems. Downward advection is a major transport mechanism into the root zone of shallow flooded aquatic systems and provides an important physical mechanism that drives variability in the seasonal and diel storage; release and cycling of COCs; and the creation of both a physical and chemical barrierd to upward diffusion of soil-borne COCs into the water column. Models that do not account for root zone interactions may not be able to capture diel and seasonal differences. Moreover, these interactions may lead to unanticipated environmental consequences as a result of cultural practices.

  3. NIGHTIME TRANSPIRATION AND NUTRIENT ACQUISITION: IS THERE A BENEFIT OF LOSING WATER AT NIGHT?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Nighttime stomatal conductance and transpiration can lead to substantial water loss occurring at non-photosynthetic times in C3 and C4 plants. Water loss without simultaneous carbon gain is intuitively wasteful, however it is possible that either there is no cost when water supply is sufficient or ...

  4. ENVIRONMENTAL AND GENETIC VARIATION INFLUENCE NIGHTTIME TRANSPIRATION IN THE C4 GRASS DISTICHLIS SPICATA

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Theory predicts that plants should close their stomata at night to decrease water loss when photosynthetic carbon gain cannot occur. However, significant nighttime stomatal conductance (g) and transpiration (E) have been measured in a wide range of species and functional groups. Little is currentl...

  5. MODELING DROUGHT IMPACT ON H. BRASILIENSIS TRANSPIRATION, GROWTH AND LATEX PRODUCTION OF A

    E-print Network

    Boyer, Edmond

    1 MODELING DROUGHT IMPACT ON H. BRASILIENSIS 2 TRANSPIRATION, GROWTH AND LATEX PRODUCTION OF A HEVEA BRASILIENSIS STAND FACING DROUGHT IN4 NORTHEAST THAILAND: THE USE OF THE WANULCAS MODEL for natural rubber, Hevea brasiliensis is16 increasingly planted in drought prone areas

  6. MORPHOLOGICAL AND PHYSIOLOGICAL INTERACTIONS IN DIVERSE PLANT COMMUNITIES

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Morphological and physiological interactions among plants in multi-species forage mixtures affect responses to environmental stresses. White clover growing under drought stress in a five-species mixture which included a deep-rooted forb had greater transpiration rates and higher leaf water potential...

  7. EFFECT, UPTAKE AND DISPOSITION OF NITROBENZENE IN SEVERAL TERRESTRIAL PLANTS

    EPA Science Inventory

    Eight species of plants were exposed to nitrobenzene in a hydroponic solution. our species experienced no depression of either transpiration or photosynthetic rates, while one was rapidly killed and the other three were temporarily affected but recovered from the treatment. ptake...

  8. Predictive Uncertainty and Scalability of Transpiration in Heterogeneous Watersheds

    Microsoft Academic Search

    D. S. Mackay; B. E. Ewers; S. Samanta; S. N. Burrows

    2003-01-01

    Spatially variable water fluxes from transpiration represent a significant and as yet largely unquantified source of uncertainty in the prediction of ungauged basins. Current models of transpiration can be traced to \\

  9. Energy conversion using thermal transpiration : optimization of a Knudsen compressor

    E-print Network

    Klein, Toby A. (Toby Anna)

    2012-01-01

    Knudsen compressors are devices without any moving parts that use the nanoscale phenomenon of thermal transpiration to pump or compress a gas. Thermal transpiration takes place when a gas is in contact with a solid boundary ...

  10. Photosynthesis and transpiration of loblolly pine seedlings as influenced by moisture-stress conditioning

    SciTech Connect

    Seiler, J.R.; Johnson, J.D.

    1985-01-01

    One-yr-old seedlings were exposed to 8 wk of moisture stress conditioning (MSC); seedlings were watered only when pre-dawn needle water potential fell below -1.4 MPa. Water was then withheld and photosynthesis and transpiration rates recorded. Photosynthesis in well-watered controls and MSC seedlings was reduced to zero in 12 and 17 days respectively. Seedlings were harvested and water use efficiency calculated using photosynthesis and transpiration data; it was expressed as mg of CO/sub 2/ fixed per g of water lost. Seedlings exposed to MSC continued to photosynthesize to much lower needle water potentials. This response is at least partly attributed to the significant decrease (0.45 MPa) in needle osmotic potential found in MSC seedlings, which were able to maintain turgor to lower needle water potentials. Transpiration rate decreased 30% and water use efficiency increased 67% as a result of MSC. 26 references.

  11. Physiologie vgtale Effet de la saison sur la transpiration

    E-print Network

    Paris-Sud XI, Université de

    Physiologie végétale Effet de la saison sur la transpiration de feuilles de rosiers cv Sonia transpiration cuticulaire (Ecut) ont été mesurés à 5 périodes différentes au cours d'une année sur des feuilles / transpiration / variation saisonnière Summary — Effect of season on the transpiration of Sonia rose leaves

  12. Free convection over a vertical porous plate with transpiration

    NASA Technical Reports Server (NTRS)

    Parikh, P. G.; Moffat, R. J.; Kays, W. M.; Bershader, D.

    1974-01-01

    The problem of free convection over an isothermal vertical porous plate with transpiration is studied both numerically and experimentally. Numerical solutions to the variable-property transpired free-convection boundary layer equations have been obtained using the finite difference procedure of Patankar and Spalding (1967). The effects of uniform transpiration on heat transfer and on temperature and velocity profiles are predicted. Interferometrically measured nondimensional temperature profiles for the uniform wall temperature and transpiration case agreed closely with these numerical predictions.

  13. Do root hydraulic properties change during the early vegetative stage of plant development in barley (Hordeum vulgare)?

    PubMed Central

    Suku, Shimi; Knipfer, Thorsten; Fricke, Wieland

    2014-01-01

    Background and Aims As annual crops develop, transpirational water loss increases substantially. This increase has to be matched by an increase in water uptake through the root system. The aim of this study was to assess the contributions of changes in intrinsic root hydraulic conductivity (Lp, water uptake per unit root surface area, driving force and time), driving force and root surface area to developmental increases in root water uptake. Methods Hydroponically grown barley plants were analysed during four windows of their vegetative stage of development, when they were 9–13, 14–18, 19–23 and 24–28 d old. Hydraulic conductivity was determined for individual roots (Lp) and for entire root systems (Lpr). Osmotic Lp of individual seminal and adventitious roots and osmotic Lpr of the root system were determined in exudation experiments. Hydrostatic Lp of individual roots was determined by root pressure probe analyses, and hydrostatic Lpr of the root system was derived from analyses of transpiring plants. Key Results Although osmotic and hydrostatic Lp and Lpr values increased initially during development and were correlated positively with plant transpiration rate, their overall developmental increases (about 2-fold) were small compared with increases in transpirational water loss and root surface area (about 10- to 40-fold). The water potential gradient driving water uptake in transpiring plants more than doubled during development, and potentially contributed to the increases in plant water flow. Osmotic Lpr of entire root systems and hydrostatic Lpr of transpiring plants were similar, suggesting that the main radial transport path in roots was the cell-to-cell path at all developmental stages. Conclusions Increase in the surface area of root system, and not changes in intrinsic root hydraulic properties, is the main means through which barley plants grown hydroponically sustain an increase in transpirational water loss during their vegetative development. PMID:24287810

  14. Reduction of tropical land region precipitation variability via transpiration

    E-print Network

    Gentine, Pierre

    Reduction of tropical land region precipitation variability via transpiration Jung-Eun Lee,1 in observations and models. In the present study, the potential role of transpiration for this difference general circulation model. Comparing model results with and without transpiration shows

  15. Optimisation des relations entre transpiration et photosynthse. Observations propos

    E-print Network

    Paris-Sud XI, Université de

    Optimisation des relations entre transpiration et photosynthèse. Observations à propos des 1977 une théorie d'optimisation des relations entre transpiration et photosynthèse chez les végétaux transpiration, F! le taux de photosynthèse nette et g, la conductance stomatiquc pour le CO2. Les études

  16. Numerical simulation of transpiration cooling through porous , T. Gotzen1

    E-print Network

    Numerical simulation of transpiration cooling through porous material W. Dahmen1 , T. Gotzen1 and S 55, 52056 Aachen SUMMARY Transpiration cooling using ceramic matrix composite (CMC) materials with experiments. KEY WORDS: Transpiration cooling, porous media flow, Darcy-Forchheimer equation, coupled finite

  17. Original article Intra-and interannual variations of transpiration,

    E-print Network

    Paris-Sud XI, Université de

    Original article Intra- and interannual variations of transpiration, leaf area index and radial), transpiration, soil water content and radial growth of a 35-year-old Quercus petraea stand were measured during. The increase of stand transpiration during spring was lin- early correlated to the development of LAI. During

  18. SEWAGE DISPOSAL BY EVAPORATION-TRANSPIRATION

    EPA Science Inventory

    One of the methods for on-site disposal of wastewater from individual homes is by evaporation. Two types of evaporative disposal systems have been investigated in this study; evapo-transpiration (ET) beds and mechanical evaporation units. Twenty nine test lysimeters of 0.22 cubic...

  19. Estimating Evaporation and Transpiration from Climatological Observations

    Microsoft Academic Search

    F. I. Morton

    1975-01-01

    Evaporation and transpiration are estimated from routine climatological observations using a conceptual model that requires no assumptions concerning the availability of water. The versatility of this unorthodox approach is demonstrated by comparing model and water budget estimates for 118 river basins in Canada, Ireland and the southern United States.

  20. Relating xylem cavitation to transpiration in cotton

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Acoustic emmisions (AEs) from xylem cavitation events are characteristic of transpiration processes. Even though a body of work employing AE exists with a large number of species, cotton and other agronomically important crops have either not been investigated, or limited information exists. A few s...

  1. Structural adjustments in resprouting trees drive differences in post-fire transpiration.

    PubMed

    Nolan, Rachael H; Mitchell, Patrick J; Bradstock, Ross A; Lane, Patrick N J

    2014-02-01

    Following disturbance many woody species are capable of resprouting new foliage, resulting in a reduced leaf-to-sapwood area ratio and altered canopy structure. We hypothesized that such changes would promote adjustments in leaf physiology, resulting in higher rates of transpiration per unit leaf area, consistent with the mechanistic framework proposed by Whitehead et al. (Whitehead D, Jarvis PG, Waring RH (1984) Stomatal conductance, transpiration and resistance to water uptake in a Pinus sylvestris spacing experiment. Can J For Res 14:692-700). We tested this in Eucalyptus obliqua L'Hér following a wildfire by comparing trees with unburnt canopies with trees that had been subject to 100% canopy scorch and were recovering their leaf area via resprouting. In resprouting trees, foliage was distributed along the trunk and on lateral branches, resulting in shorter hydraulic path lengths. We evaluated measurements of whole-tree transpiration and structural and physiological traits expected to drive any changes in transpiration. We used these structural and physiological measurements to parameterize the Whitehead et al. equation, and found that the expected ratio of transpiration per unit leaf area between resprouting and unburnt trees was 3.41. This is similar to the observed ratio of transpiration per unit leaf area, measured from sapflow observations, which was 2.89 (i.e., resprouting trees had 188% higher transpiration per unit leaf area). Foliage at low heights (<2 m) was found to be significantly different to foliage in the tree crown (14-18 m) in a number of traits, including higher specific leaf area, midday leaf water potential and higher rates of stomatal conductance and photosynthesis. We conclude that these post-fire adjustments in resprouting trees help to drive increased stomatal conductance and hydraulic efficiency, promoting the rapid return of tree-scale transpiration towards pre-disturbance levels. These transient patterns in canopy transpiration have important implications for modelling stand-level water fluxes in forests capable of resprouting, which is frequently done on the basis of the leaf area index. PMID:24536069

  2. Influence of leaf size, orientation, and arrangement on temperature and transpiration in three high-elevation, large-leafed herbs

    Microsoft Academic Search

    G. N. Geller; W. K. Smith

    1982-01-01

    The temperature and water relations of the largleafed, high-elevation species Frasera speciosa, Balsamorhiza sagittata, and Rumex densiflorus were evaluated in the Medicine Bow Mountains of southeast Wyoming (USA) to determine the influence of leaf size, orientation, and arrangement on transpiration. These species characteristically have low minimum stomatal resistances (-1) and high maximum transpiration rates (>260 mg m-2s-1 for F. speciosa).

  3. Oxygen isotope signatures of transpired water vapor - the role of isotopic non-steady-state transpiration of Mediterranean cork-oaks (Quercus suber L.)under natural conditions

    NASA Astrophysics Data System (ADS)

    Dubbert, Maren; Piayda, Arndt; Cuntz, Matthias; Werner, Christiane

    2014-05-01

    Oxygen isotope signatures of transpired water vapor (?T) are a powerful tracer of water movement from plants to the global scale, but little is known on short-term variability of ?T as direct high-frequency measurements are lacking. A laser spectrometer was coupled to a gas-exchange chamber directly estimating branch-level fluxes and ?T to evaluate a modeling approach and investigate the role of isotopic non-steady-state transpiration under natural conditions in distinct seasons in cork-oaks (Quercus suber L.). The isotope signature of transpiration (?T) always deviated from steady-state predictions (?T) throughout most of the day even when leaf water at the evaporating sites is near isotopic steady-state. Thus, ?T is further amplified compared to deviations of leaf water isotopes from steady-state, specifically in dry conditions. High agreement was found for direct estimates and modeled ?T assuming non-steady-state conditions of leaf-water at the evaporating sites. Strong isoforcing on the atmosphere of transpiration in isotopic non-steady-state imply that short-term variations in ?T have likely consequences for large-scale applications, e.g. partitioning of ecosystem evapotranspiration or carbon fluxes using C18O16O, or satellite-based applications.

  4. Transpiration characteristics of a rubber plantation in central Cambodia.

    PubMed

    Kobayashi, Nakako; Kumagai, Tomo'omi; Miyazawa, Yoshiyuki; Matsumoto, Kazuho; Tateishi, Makiko; Lim, Tiva K; Mudd, Ryan G; Ziegler, Alan D; Giambelluca, Thomas W; Yin, Song

    2014-03-01

    The rapid and widespread expansion of rubber plantations in Southeast Asia necessitates a greater understanding of tree physiology and the impacts of water consumption on local hydrology. Sap flow measurements were used to study the intra- and inter-annual variations in transpiration rate (Et) in a rubber stand in the low-elevation plain of central Cambodia. Mean stand sap flux density (JS) indicates that rubber trees actively transpire in the rainy season, but become inactive in the dry season. A sharp, brief drop in JS occurred simultaneously with leaf shedding in the middle of the dry season in January. Although the annual maxima of JS were approximately the same in the two study years, the maximum daily stand Et of ?2.0 mm day(-1) in 2010 increased to ?2.4 mm day(-1) in 2011. Canopy-level stomatal response was well explained by changes in solar radiation, vapor pressure deficit, soil moisture availability, leaf area, and stem diameter. Rubber trees had a relatively small potential to transpire at the beginning of the study period, compared with average diffuse-porous species. After 2 years of growth in stem diameter, transpiration potential was comparable to other species. The sensitivity of canopy conductance (gc) to atmospheric drought indicates isohydric behavior of rubber trees. Modeling also predicted a relatively small sensitivity of gc to the soil moisture deficit and a rapid decrease in gc under extreme drought conditions. However, annual observations suggest the possibility of a change in leaf characteristics with tree maturity and/or initiation of latex tapping. The estimated annual stand Et was 469 mm year(-1) in 2010, increasing to 658 mm year(-1) in 2011. Diagnostic analysis using the derived gc model showed that inter-annual change in stand Et in the rapidly growing young rubber stand was determined mainly by tree growth rate, not by differences in air and soil variables in the surrounding environment. Future research should focus on the potentially broad applicability of the relationship between Et and tree size as well as environmental factors at stands different in terms of clonal type and age. PMID:24646689

  5. An improved temporal formulation of pupal transpiration in Glossina.

    PubMed

    Childs, S J

    2015-04-01

    The temporal aspect of a model of pupal dehydration is improved upon. The observed dependence of pupal transpiration on time is attributed to an alternation between two, essential modes, for which the deposition of a thin, pupal skin inside the puparium and its subsequent demise are thought to be responsible. For each mode of transpiration, the results of the Bursell [1] investigation into pupal dehydration are used as a rudimentary data set. These data are generalised to all temperatures and humidities by invoking the property of multiplicative separability. The problem, then, is that as the temperature varies with time, so does the metabolism and the developmental stages to which the model data pertain, must necessarily warp. The puparial-duration formula of Phelps and Burrows [19] and Hargrove [16] is exploited to facilitate a mapping between the constant-temperature time domain of the data and that of some, more general case at hand. The resulting, Glossina morsitans model is extrapolated to other species using their relative surface areas, their relative protected and unprotected transpiration rates and their different fourth instar excretions (drawing, to a lesser extent, from the data of Buxton and Lewis [4]). In this way the problem of pupal dehydration is formulated as a series of integrals and the consequent survival can be predicted. The discovery of a distinct definition for hygrophilic species, within the formulation, prompts the investigation of the hypothetical effect of a two-day heat wave on pupae. This leads to the conclusion that the classification of species as hygrophilic, mesophilic and xerophilic is largely true only in so much as their third and fourth instars are and, possibly, the hours shortly before eclosion. PMID:25676558

  6. Make Your Own Transpiring Tree

    ERIC Educational Resources Information Center

    Martinez Vilalta, Jordi; Sauret, Miquel; Duro, Alicia; Pinol, Josep

    2003-01-01

    In this paper we present a simple set-up that illustrates the mechanism of sap ascent in plants and demonstrates that it can easily draw water up to heights of a few meters. The set-up consists of a tube with the lower end submerged in water and the upper one connected to a filter supported by a standard filter-holder. The evaporation of water…

  7. Visiting insect diversity and visitation rates for seven globally-imperiled plant species in

    E-print Network

    Visiting insect diversity and visitation rates for seven globally-imperiled plant species of Natural Resources, Colorado State University Ft. Collins, Colorado prepared for Native Plant Conservation......................................................................................................................................... 20 Rare plant inventory and assessments

  8. Studies of shock/shock interaction on smooth and transpiration-cooled hemispherical nosetips in hypersonic flow

    NASA Technical Reports Server (NTRS)

    Holden, M. S.; Rodriguez, K. M.; Nowak, R. J.

    1991-01-01

    Experimental studies are conducted to examine the utilization of transpiration cooling to reduce the peak-heating loads in areas of shock/shock interaction. Smooth and transpiration-cooled nosetip models, 12 inches in diameter, were employed in these studies, which focused on defining the pressure distributions and heat transfer in type III and IV interaction areas. Transpiration cooling was determined to significantly increase the size of the shock layer and to move the peak-heating point around the body. A transpiration-cooling rate of more than 30 percent of the freestream maximum flux did not lower the peak-heating level more than 10 percent, but the integrated heating loads were reduced.

  9. TEMPORAL AND SPATIAL CHANGES IN GRASSLAND TRANSPIRATION DETECTED USING LANDSAT AND ETM+ IMAGERY 1440

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Water Deficit Index (WDI) derived from Landsat imagery was used to detect temporal and spatial changes in grassland transpiration. The WDI, which estimates relative evapotranspiration rates based on meteorological data and the relation between surface reflectance and temperature, has been succe...

  10. Transpired Air Collectors - Ventilation Preheating

    SciTech Connect

    Christensen, C.

    2006-06-22

    Many commercial and industrial buildings have high ventilation rates. Although all that fresh air is great for indoor air quality, heating it can be very expensive. This short (2-page) fact sheet describes a technology available to use solar energy to preheat ventilation air and dramatically reduce utility bills.

  11. Preciptation, Evaporation, and Transpiration Activity

    NSDL National Science Digital Library

    Amy Townsend-Small

    The students must use crayons or colored pencils to create maps of global precipitation and evaporation rates. One worksheet is provided to each group of students. Then a representative from each group explains their map to the rest of the class, and the instructor shows a similar map from NOAA or NASA.

  12. NRES 725 Plant Physiological Ecology Spring 2013 Leaf Energy Balance --Sample Problem Set

    E-print Network

    Nowak, Robert S.

    and transpiration were zero? (52.8 C) 1.d) If leaf temperature is 34 C, how much heat must be dissipated by convection and transpiration? (257 W m-2 ) 1.e) How much heat would need to be dissipated by transpiration if leaf temperature was 26 C? (496 W m-2 ) 1.f) What transpiration rate would be needed to sustain

  13. Transpired solar air heaters. Volume 1. Investigation of transpired porous-bed solar air heaters. Final report

    SciTech Connect

    Galanter, S.A.

    1980-11-01

    Tests were conducted to determine the thermal performance of a number of transpired porous-bed solar air heaters. Improvements were made to a reference double-glazed transpired solar air heater and the performance experimentally determined. An air heater incorporating two parallel glass-plate honeycombs for air heater incorporating two parallel glass-plate honeycombs for heat-loss control was also tested. The performance of the double-honeycomb collector proved to be superior to the reference solar air heater's due to the increased transmittance of the coverglass assembly. Both collectors exhibited performance greater than any current state-of-the-art collectors. Two steady-state performance models of the reference double-glazed solar air heater were formulated. One (reference model) incorporated the theoretical work of Edwards and Leung to predict the air temperature rise through the porous bed while the other assumed an isothermal bed with a heat-exchanger effectiveness of one. An energy balance was performed at each collector element, and the resultant system of nonlinear equations was solved iteratively to predict the collector's performance. Air recirculation above the porous bed was modeled using the reference formulation. Collector performance was predicted closely using the isothermal bed model. The reference model yielded close prediction using a recirculation rate of 20%.

  14. Planting Thoughts

    NSDL National Science Digital Library

    2014-09-18

    Students gain an understanding of the parts of a plant, plant types and how they produce their own food from sunlight through photosynthesis. They also learn about transpiration, the process by which plants release moisture to the atmosphere. With this understanding, students test the effects of photosynthesis and transpiration by growing a plant from seed. They learn how plants play an important part in maintaining a balanced environment in which the living organisms of the Earth survive. This lesson is part of a series of six lessons in which students use their evolving understanding of various environments and the engineering design process, to design and create their own model biodome ecosystems.

  15. Article original Utilisation d'une chambre de transpiration portable

    E-print Network

    Paris-Sud XI, Université de

    Article original Utilisation d'une chambre de transpiration portable pour l'estimation de l chambre de transpiration légère, close, couvrant une surface au sol de 0,5 m2 a été utilisée pour mesurer comparées avec la transpiration des arbres estimée à partir de mesures de flux de sève. Quand le stock

  16. Urban tree transpiration over turf and asphalt surfaces

    Microsoft Academic Search

    Roger Kjelgren; Thayne Montague

    1998-01-01

    We used a two-layer canopy model to study transpiration of tree species as affected by energy-balance properties of a vegetated and paved surface. During several dawn-to-dusk studies, tree transpiration, stomatal conductance, leaf temperature (Tl), and several microclimate variables, were measured over turf and an asphalt surface. Cumulative transpiration was estimated from a leaf energy-balance equation applied to a tree crown

  17. Night-time transpiration can decrease hydraulic redistribution.

    PubMed

    Howard, Ava R; van Iersel, Marc W; Richards, James H; Donovan, Lisa A

    2009-08-01

    C(3) plants dominate many landscapes and are critically important for ecosystem water cycling. At night, plant water losses can include transpiration (E(night)) from the canopy and hydraulic redistribution (HR) from roots. We tested whether E(night) limits the magnitude of HR in a greenhouse study using Artemisia tridentata, Helianthus anomalus and Quercus laevis. Plants were grown with their roots split between two compartments. HR was initiated by briefly withholding all water, followed by watering only one rooting compartment. Under study conditions, all species showed substantial E(night) and HR (highest minus lowest soil water potential [Psi(s)] during a specified diel period). Suppressing E(night) by canopy bagging increased HR during the nightly bagging period (HR(N)) for A. tridentata and H. anomalus by 73 and 33% respectively, but did not affect HR(N) by Q. laevis. Total daily HR (HR(T)) was positively correlated with the Psi(s) gradient between the rooting compartments, which was correlated with light and/or atmospheric vapour pressure deficit (VPDa) the prior day. For A. tridentata, HR(T) was negatively correlated with night-time VPDa. Ecological implications of the impact of E(night) on HR may include decreased plant productivity during dry seasons, altered ecosystem water flux patterns and reduced nutrient cycling in drying soils. PMID:19422615

  18. Thermal transpiration: A molecular dynamics study

    NASA Astrophysics Data System (ADS)

    T, Joe Francis; Sathian, Sarith P.

    2014-12-01

    Thermal transpiration is a phenomenon where fluid molecules move from the cold end towards the hot end of a channel under the influence of longitudinal temperature gradient alone. Although the phenomenon of thermal transpiration is observed at rarefied gas conditions in macro systems, the phenomenon can occur at atmospheric pressure if the characteristic dimensions of the channel is less than 100 nm. The flow through these nanosized channels is characterized by the free molecular flow regimes and continuum theory is inadequate to describe the flow. Thus a non-continuum method like molecular dynamics (MD) is necessary to study such phenomenon. In the present work, MD simulations were carried out to investigate the occurance of thermal transpiration in copper and platinum nanochannels at atmospheric pressure conditions. The mean pressure of argon gas confined inside the nano channels was maintained around 1 bar. The channel height is maintained at 2nm. The argon atoms interact with each other and with the wall atoms through the Lennard-Jones potential. The wall atoms are modelled using an EAM potential. Further, separate simulations were carried out where a Harmonic potential is used for the atom-atom interaction in the platinum channel. A thermally insulating wall was introduced between the low and high temperature regions and those wall atoms interact with fluid atoms through a repulsive potential. A reduced cut off radius were used to achieve this. Thermal creep is induced by applying a temperature gradient along the channel wall. It was found that flow developed in the direction of the increasing temperature gradient of the wall. An increase in the volumetric flux was observed as the length of the cold and the hot regions of the wall were increased. The effect of temperature gradient and the wall-fluid interaction strength on the flow parameters have been studied to understand the phenomenon better.

  19. Heat exchanger with transpired, highly porous fins

    DOEpatents

    Kutscher, Charles F. (Golden, CO); Gawlik, Keith (Boulder, CO)

    2002-01-01

    The heat exchanger includes a fin and tube assembly with increased heat transfer surface area positioned within a hollow chamber of a housing to provide effective heat transfer between a gas flowing within the hollow chamber and a fluid flowing in the fin and tube assembly. A fan is included to force a gas, such as air, to flow through the hollow chamber and through the fin and tube assembly. The fin and tube assembly comprises fluid conduits to direct the fluid through the heat exchanger, to prevent mixing with the gas, and to provide a heat transfer surface or pathway between the fluid and the gas. A heat transfer element is provided in the fin and tube assembly to provide extended heat transfer surfaces for the fluid conduits. The heat transfer element is corrugated to form fins between alternating ridges and grooves that define flow channels for directing the gas flow. The fins are fabricated from a thin, heat conductive material containing numerous orifices or pores for transpiring the gas out of the flow channel. The grooves are closed or only partially open so that all or substantially all of the gas is transpired through the fins so that heat is exchanged on the front and back surfaces of the fins and also within the interior of the orifices, thereby significantly increasing the available the heat transfer surface of the heat exchanger. The transpired fins also increase heat transfer effectiveness of the heat exchanger by increasing the heat transfer coefficient by disrupting boundary layer development on the fins and by establishing other beneficial gas flow patterns, all at desirable pressure drops.

  20. Lattice Boltzmann approach to thermal transpiration

    SciTech Connect

    Sofonea, Victor [Center for Fundamental and Advanced Technical Research, Romanian Academy, Bd. Mihai Viteazul 24, RO - 300223 Timisoara (Romania)

    2006-11-15

    Diffuse reflection boundary conditions are introduced in a thermal lattice Boltzmann model to allow for variable fluid density and temperature along the walls. The capability of this model to capture the main characteristics of the thermal transpiration phenomenon in a box at nonvanishing Knudsen numbers is demonstrated. The thermal creep velocity is found to be proportional to the temperature gradient imposed at the wall, whereas the accuracy of the simulation results are found to be of first or second order, depending on the numerical scheme.

  1. Simultaneous viscous-inviscid coupling via transpiration

    SciTech Connect

    Yiu, K.F.C.; Giles, M.B. [Oxford Univ. Computing Lab. (United Kingdom)] [Oxford Univ. Computing Lab. (United Kingdom)

    1995-09-01

    In viscous-inviscid coupling analysis, the direct coupling technique and the inverse coupling technique are commonly adopted. However, stability and convergence of the algorithms derived are usually very unsatisfactory. Here, by using the transpiration technique to simulate the effect of the displacement thickness, a new simultaneous coupling method is derived. The integral boundary layer equations and the full potential equation are chosen to be the viscous-inviscid coupled system. After discretization, the Newton-Raphson technique is proposed to solve the coupled nonlinear system. Several numerical results are used to demonstrate the accuracy and efficiency of the proposed method. 15 refs., 23 figs.

  2. Effect of planting date, nitrogen rate, and plant spacing on potatoes grown for processing in Prince Edward Island

    Microsoft Academic Search

    R. P. White; J. B. Sanderson

    1983-01-01

    Russet Burbank and Kennebec potatoes were evaluated over 5 years at 3 planting dates, 3 plant spacings, and 3 nitrogen rates.\\u000a Delayed planting significantly reduced Russet Burbank yield, but did not effect Kennebec yield. Both varieties exhibited reduced\\u000a specific gravity of tubers with delayed planting. Spacings between 38 and 56 cm for Russet Burbank and 20 and 38 cm for

  3. Evaluation of the tritiated water method for measurement of transpiration in young Pinus taeda L

    SciTech Connect

    Luvall, J.C. (Univ. of Georgia, Athens); Murphy, C.E., Jr.

    1982-03-01

    The tritiated water (HTO) technique was evaluated as a method for measurement of transpiration of young loblolly pine. Twenty-one millicuries of tritium in 3 ml of water were injected into holes drilled at the base of the trees. The transpiration rate was estimated to average 8.3 liters/day per tree for three trees injected in February and 40.4 liters/day for a single tree injected in July. Several methods of collecting the water from the trees for tritium analysis were evaluated. The collection of water by condensation in clear plastic bags sealed around branch tips proved to be a simple, reliable method of collecting water. Difference in the integral tritium activity with distance from the injection site were found. Serious errors in the estimation of transpiration are possible if the difference in tritium activity in the canopy are not taken into account. The activity measured in the water collected nearest the injection point provided good estimation of transpiration when compared to evaporation determined by a soil water balance or by the Penman-Monteith evaporation formula.

  4. Seasonal and interannual variability of canopy transpiration of a hedgerow in southern England.

    PubMed

    Herbst, Mathias; Roberts, John M; Rosier, Paul T W; Gowing, David J

    2007-03-01

    Transpiration from a hawthorn (Crataegus monogyna L.) dominated hedgerow in southern England was measured continuously over two growing seasons by the sap flow technique. Accompanying measurements of structural parameters, microclimate and leaf stomatal and boundary layer conductances were used to establish the driving factors of hedgerow transpiration. Observed transpiration rates, reaching peak values of around 8 mm day(-1) and a seasonal mean of about 3.5 mm day(-1), were higher than those reported for most other temperate deciduous woodlands, except short-rotation coppice and wet woodlands. The high rates were caused by the structural and physiological characteristics of hawthorn leaves, which exhibited much higher stomatal and boundary-layer conductances than those of the second-most abundant woody species in the hedgerow, field maple (Acer campestre L.). Only in the hot summer of 2003 did stomatal conductance, and thus transpiration, decrease substantially. The hedgerow canopy was always closely coupled to the atmosphere. Hedgerow transpiration equaled potential evaporation (calculated by the Priestley-Taylor formula) in 2003 and exceeded it in 2004, which meant that a substantial fraction of the energy (21% in 2003 and more than 37% in 2004) came from advection. Hedgerow canopy conductance (g(c)), as inferred from the sap flow data by inverting the Penman-Monteith equation, responded to solar radiation (R(G)) and vapor pressure deficit (D). Although the response to R(G) showed no systematic temporal variation, the response to D, described as g(c)(D) = g(cref) - mln(D), changed seasonally. The reference g(c) depended on leaf area index and the ratio of -m/g(cref) on long-term mean daytime D. A model is proposed based on these observations that predicts canopy conductance for the hawthorn hedge from standard weather data. PMID:17241974

  5. Transpiration and water relations of poplar trees growing close to the water table.

    PubMed

    Zhang, Heping; Morison, James I. L.; Simmonds, Lester P.

    1999-07-01

    Sap flow was measured on five branches of two poplar (Populus trichocarpa Torr. & A. Gray x P. tacamahaca L.) trees from June to September 1994 in the south of England with stem-surface, heat balance gauges, and was scaled up to estimate transpiration from single trees on the basis of leaf area. On six days, stomatal conductance and plant water potential were measured simultaneously with a porometer and pressure chamber, respectively. The effects of solar radiation (S), vapor pressure deficit (D) and stomatal conductance on transpiration were evaluated. Sap flow per unit leaf area (F(a)) was closely related to the time course of demand attributable to S and D throughout the season, and only slightly affected by the water content of the top 120 cm of soil. Although F(a) increased linearly at low values of D, it showed a plateau with increases in D above 1.2 kPa. The canopy coupling coefficient (1 - Omega) ranged from 0.48 to 0.78 with a mean of 0.65 +/- 0.01, indicating that transpiration was controlled more by stomatal conductance than by incident radiation. The seasonal pattern of tree water loss followed potential evaporation with a peak in late June or early July. On bright days, daily transpiration over the projected crown area was 3.6 mm early in the season, 3.8 mm in mid-season, and 2.7 mm late in the season. The water balance of the system indicated that poplar trees took 15-60% of water transpired from groundwater, with the proportion increasing as the soil in the unsaturated zone dried out. Access to the water table resulted in high predawn water potentials throughout the season. Estimated hydraulic resistance to water flow in the soil-tree system was in the range of 1.5 to 1.93 x 10(6) MPa s m(-3). PMID:12651530

  6. ESTIMATES OF ISOPRENE AND MONOTERPENE EMISSION RATES IN PLANTS

    EPA Science Inventory

    A range of plant species, including crops, shrubs, herbs, and trees, was surveyed to determine the magnitude of isoprene emissions. In studies to determine if plants emitted isoprene, greenhouse-grown plants were encapsulated in impermeable plastic bags and kept in a growth chamb...

  7. Real-time variable rate Pix® application system using a plant height sensor

    E-print Network

    Beck, Andy Dwayne

    2001-01-01

    The objective of this study was to develop a chemical application system that could measure plant size, determine the optimum chemical rate to apply and control that application. A plant height sensor, the MEPRT growth relationship software...

  8. Dynamic aspects of soil water availability for isohydric plants: Focus on root hydraulic resistances

    NASA Astrophysics Data System (ADS)

    Couvreur, V.; Vanderborght, J.; Draye, X.; Javaux, M.

    2014-11-01

    Soil water availability for plant transpiration is a key concept in agronomy. The objective of this study is to revisit this concept and discuss how it may be affected by processes locally influencing root hydraulic properties. A physical limitation to soil water availability in terms of maximal flow rate available to plant leaves (Qavail) is defined. It is expressed for isohydric plants, in terms of plant-centered variables and properties (the equivalent soil water potential sensed by the plant, ?s eq; the root system equivalent conductance, Krs; and a threshold leaf water potential, ?leaf lim). The resulting limitation to plant transpiration is compared to commonly used empirical stress functions. Similarities suggest that the slope of empirical functions might correspond to the ratio of Krs to the plant potential transpiration rate. The sensitivity of Qavail to local changes of root hydraulic conductances in response to soil matric potential is investigated using model simulations. A decrease of radial conductances when the soil dries induces earlier water stress, but allows maintaining higher night plant water potentials and higher Qavail during the last week of a simulated 1 month drought. In opposition, an increase of radial conductances during soil drying provokes an increase of hydraulic redistribution and Qavail at short term. This study offers a first insight on the effect of dynamic local root hydraulic properties on soil water availability. By better understanding complex interactions between hydraulic processes involved in soil-plant hydrodynamics, better prospects on how root hydraulic traits mitigate plant water stress might be achieved.

  9. Applying Scaled Vegetation Greenness Metrics to Constrain Simulated Transpiration Anomalies: A Study over Australia*

    E-print Network

    Evans, Jason

    Applying Scaled Vegetation Greenness Metrics to Constrain Simulated Transpiration Anomalies The feasibility of using vegetation greenness metrics as a proxy for transpiration variability over Australia is demonstrated. Several global evapotranspiration datasets, one of which provides transpiration data

  10. Desiccant cooling using unglazed transpired solar collectors

    SciTech Connect

    Pesaran, A.A. (National Renewable Energy Lab., Golden, CO (United States)); Wipke, K. (Stanford Univ., CA (United States))

    1992-05-01

    The use of unglazed solar collectors for desiccant regeneration in a solid desiccant cooling cycle was investigated because these collectors are lower in cost than conventional glazed flat-plate collectors. Using computer models, the performance of a desiccant cooling ventilation cycle integrated with either unglazed transpired collectors or conventional glazed flat-plate collectors was obtained. We found that the thermal performance of the unglazed system was lower than the thermal performance of the glazed system because the unglazed system could not take advantage of the heat of adsorption released during the dehumidification process. For a 3-ton cooling system, although the area required for the unglazed collector was 69% more than that required for the glazed collector, the cost of the unglazed collector array was 44% less than the cost of the glazed collector array. The simple payback period of the unglazed system was half of the payback period of the glazed collector when compared to an equivalent gas-fired system. Although the use of unglazed transpired collectors makes economic sense, some practical considerations may limit their use in desiccant regeneration. 8 refs.

  11. Combustion chamber struts can be effectively transpiration cooled

    NASA Technical Reports Server (NTRS)

    Palmer, G. H.

    1966-01-01

    Vapor-deposited sintering technique increases the feasible temperature range of transpiration-cooled structural members in combustion chambers. This technique produces a porous mass of refractory metal wires around a combustion chamber structural member. This mass acts as a transpiration-cooled surface for a thick-walled tube.

  12. The relative role of stomata in transpiration and assimilation

    Microsoft Academic Search

    I. R. Cowan; J. H. Troughton

    1971-01-01

    The ways in which transpiration and assimilation depend on stomatal aperture are compared. It is shown that transpiration and assimilation are equally sensitive to change of stomatal aperture when the internal resistance to assimilation is equal to an effective resistance to evaporation which exists because of the coupling of heat and vapour exchanges between leaf and atmosphere. Generally the ratio

  13. A Generic Model for a Transpiration Cooled Fusion Propulsion System

    Microsoft Academic Search

    Dejan P ETKOW; Georg H ERDRICH; Rene L AUFER; Oliver Z EILE; Universitaet Stuttgart

    In the present work we discuss a generic model of a reactor which is surrounded by a transpiration cooled wall. We facilitate the energy balance equation in order to estimate the power fluxes across the system and sub system boundaries. The transpiration cooled reactor wall is modeled on the basis of a simplified heat transfer equation. The four fusion propellants

  14. Temperature interactions with transpiration response to vapor pressure deficit among cultivated and wild soybean genotypes.

    PubMed

    Seversike, Thomas M; Sermons, Shannon M; Sinclair, Thomas R; Carter, Thomas E; Rufty, Thomas W

    2013-05-01

    A key strategy in soybean drought research is increased stomatal sensitivity to high vapor pressure deficit (VPD), which contributes to the 'slow wilting' trait observed in the field. These experiments examined whether temperature of the growth environment affected the ability of plants to respond to VPD, and thus control transpiration rate (TR). Two soybean [Glycine max (L.) Merr.] and four wild soybean [Glycine soja (Sieb. and Zucc.)] genotypes were studied. The TR was measured over a range of VPD when plants were growing at 25 or 30°C, and again after an abrupt increase of 5°C. In G. max, a restriction of TR became evident as VPD increased above 2.0?kPa when temperature was near its growth optimum of 30°C. 'Slow wilting' genotype plant introduction (PI) 416937 exhibited greater TR control at high VPD compared with Hutcheson, and only PI 416937 restrained TR after the shift to 35°C. Three of the four G. soja genotypes exhibited control over TR with increasing VPD when grown at 25°C, which is near their estimated growth optimum. The TR control became engaged at lower VPD than in G. max and was retained to differing degrees after a shift to 30°C. The TR control systems in G. max and G. soja clearly were temperature-sensitive and kinetically definable, and more restrictive in the 'slow wilting' soybean genotype. For the favorable TR control traits observed in G. soja to be useful for soybean breeding in warmer climates, the regulatory linkage with lower temperatures must be uncoupled. PMID:22989317

  15. Determining the Amount of Transpiration from a Schoolyard Tree

    NSDL National Science Digital Library

    2012-07-11

    In this activity, learners calculate the number of milliliters of water a nearby tree transpires per day. First, teams of learners go outdoors to collect five leaves from a mulberry or cottonwood tree. Next, learners calculate the area of each leaf and the total area of the five leaves together. Then, learners submerge the leaves in a beaker half full of spring water with a small layer of mineral oil on top. After 24 hours, learners estimate how many milliliters of water "transpired" (dropped) and divide this number by the total area of the five leaves to calculate the amount of water transpired in milliliters per square centimeter of leaf in 24 hours. Then, they make a few more calculations to obtain the number of milliliters transpired by the whole tree in one day. This lesson guide includes other calculations that learners can compute including the number of liters of water transpired per day and the yearly water loss.

  16. American Institute of Aeronautics and Astronautics Variable Transpiration Cooling: A New Solution

    E-print Network

    Texas at Arlington, University of

    American Institute of Aeronautics and Astronautics 1 Variable Transpiration Cooling: A New Solution. The variable transpiration is obtained choosing selected distributions for the coolant (air) velocity

  17. Plant genotypic diversity reduces the rate of consumer resource utilization

    PubMed Central

    McArt, Scott H.; Thaler, Jennifer S.

    2013-01-01

    While plant species diversity can reduce herbivore densities and herbivory, little is known regarding how plant genotypic diversity alters resource utilization by herbivores. Here, we show that an invasive folivore—the Japanese beetle (Popillia japonica)—increases 28 per cent in abundance, but consumes 24 per cent less foliage in genotypic polycultures compared with monocultures of the common evening primrose (Oenothera biennis). We found strong complementarity for reduced herbivore damage among plant genotypes growing in polycultures and a weak dominance effect of particularly resistant genotypes. Sequential feeding by P. japonica on different genotypes from polycultures resulted in reduced consumption compared with feeding on different plants of the same genotype from monocultures. Thus, diet mixing among plant genotypes reduced herbivore consumption efficiency. Despite positive complementarity driving an increase in fruit production in polycultures, we observed a trade-off between complementarity for increased plant productivity and resistance to herbivory, suggesting costs in the complementary use of resources by plant genotypes may manifest across trophic levels. These results elucidate mechanisms for how plant genotypic diversity simultaneously alters resource utilization by both producers and consumers, and show that population genotypic diversity can increase the resistance of a native plant to an invasive herbivore. PMID:23658201

  18. EFFECTS OF ELEVATED ATMOSPHERIC CO{sub 2} ON CANOPY TRANSPIRATION IN SENESCENT SPRING WHEAT

    SciTech Connect

    GROSSMAN,S.; KIMBALL,B.A.; HUNSAKER,D.J.; LONG,S.P.; GARCIA,R.L.; KARTSCHALL,TH.; WALL,G.W.; PINTER,P.J,JR.; WECHSUNG,F.; LAMORTE,R.L.

    1998-12-31

    The seasonal course of canopy transpiration and the diurnal courses of latent heat flux of a spring wheat crop were simulated for atmospheric CO{sub 2} concentrations of 370 {micro}mol mol{sup {minus}1} and 550 {micro}mol mol{sup {minus}1}. The hourly weather data, soil parameters and the irrigation and fertilizer treatments of the Free-Air Carbon Dioxide Enrichment wheat experiment in Arizona (1992/93) were used to drive the model. The simulation results were tested against field measurements with special emphasis on the period between anthesis and maturity. A model integrating leaf photosynthesis and stomatal conductance was scaled to a canopy level in order to be used in the wheat growth model. The simulated intercellular CO{sub 2} concentration, C{sub i} was determined from the ratio of C{sub i} to the CO{sub 2} concentration at the leaf surface, C{sub s} the leaf to air specific humidity deficit and a possibly unfulfilled transpiration demand. After anthesis, the measured assimilation rates of the flag leaves decreased more rapidly than their stomatal conductances, leading to a rise in the C{sub i}/C{sub s} ratio. In order to describe this observation, an empirical model approach was developed which took into account the leaf nitrogen content for the calculation of the C{sub i}/C{sub s} ratio. Simulation results obtained with the new model version were in good agreement with the measurements. If changes in the C{sub i}/C{sub s} ratio accorded to the decrease in leaf nitrogen content during leaf senescence were not considered in the model, simulations revealed an underestimation of the daily canopy transpiration of up to 20% and a decrease in simulated seasonal canopy transpiration by 10%. The measured reduction in the seasonal sum of canopy transpiration and soil evaporation owing to CO{sub 2} enrichment, in comparison, was only about 5%.

  19. A new look at water transport regulation in plants.

    PubMed

    Martínez-Vilalta, Jordi; Poyatos, Rafael; Aguadé, David; Retana, Javier; Mencuccini, Maurizio

    2014-10-01

    Plant function requires effective mechanisms to regulate water transport at a variety of scales. Here, we develop a new theoretical framework describing plant responses to drying soil, based on the relationship between midday and predawn leaf water potentials. The intercept of the relationship (?) characterizes the maximum transpiration rate per unit of hydraulic transport capacity, whereas the slope (?) measures the relative sensitivity of the transpiration rate and plant hydraulic conductance to declining water availability. This framework was applied to a newly compiled global database of leaf water potentials to estimate the values of ? and ? for 102 plant species. Our results show that our characterization of drought responses is largely consistent within species, and that the parameters ? and ? show meaningful associations with climate across species. Parameter ? was ?1 in most species, indicating a tight coordination between the gas and liquid phases of water transport, in which canopy transpiration tended to decline faster than hydraulic conductance during drought, thus reducing the pressure drop through the plant. The quantitative framework presented here offers a new way of characterizing water transport regulation in plants that can be used to assess their vulnerability to drought under current and future climatic conditions. PMID:24985503

  20. Transpiration and Root Development of Urban Trees in Structural Soil Stormwater Reservoirs

    NASA Astrophysics Data System (ADS)

    Bartens, Julia; Day, Susan D.; Harris, J. Roger; Wynn, Theresa M.; Dove, Joseph E.

    2009-10-01

    Stormwater management that relies on ecosystem processes, such as tree canopy interception and rhizosphere biology, can be difficult to achieve in built environments because urban land is costly and urban soil inhospitable to vegetation. Yet such systems offer a potentially valuable tool for achieving both sustainable urban forests and stormwater management. We evaluated tree water uptake and root distribution in a novel stormwater mitigation facility that integrates trees directly into detention reservoirs under pavement. The system relies on structural soils: highly porous engineered mixes designed to support tree root growth and pavement. To evaluate tree performance under the peculiar conditions of such a stormwater detention reservoir (i.e., periodically inundated), we grew green ash ( Fraxinus pennsylvanica Marsh.) and swamp white oak ( Quercus bicolor Willd.) in either CUSoil or a Carolina Stalite-based mix subjected to three simulated below-system infiltration rates for two growing seasons. Infiltration rate affected both transpiration and rooting depth. In a factorial experiment with ash, rooting depth always increased with infiltration rate for Stalite, but this relation was less consistent for CUSoil. Slow-drainage rates reduced transpiration and restricted rooting depth for both species and soils, and trunk growth was restricted for oak, which grew the most in moderate infiltration. Transpiration rates under slow infiltration were 55% (oak) and 70% (ash) of the most rapidly transpiring treatment (moderate for oak and rapid for ash). We conclude this system is feasible and provides another tool to address runoff that integrates the function of urban green spaces with other urban needs.

  1. Transpiration and root development of urban trees in structural soil stormwater reservoirs.

    PubMed

    Bartens, Julia; Day, Susan D; Harris, J Roger; Wynn, Theresa M; Dove, Joseph E

    2009-10-01

    Stormwater management that relies on ecosystem processes, such as tree canopy interception and rhizosphere biology, can be difficult to achieve in built environments because urban land is costly and urban soil inhospitable to vegetation. Yet such systems offer a potentially valuable tool for achieving both sustainable urban forests and stormwater management. We evaluated tree water uptake and root distribution in a novel stormwater mitigation facility that integrates trees directly into detention reservoirs under pavement. The system relies on structural soils: highly porous engineered mixes designed to support tree root growth and pavement. To evaluate tree performance under the peculiar conditions of such a stormwater detention reservoir (i.e., periodically inundated), we grew green ash (Fraxinus pennsylvanica Marsh.) and swamp white oak (Quercus bicolor Willd.) in either CUSoil or a Carolina Stalite-based mix subjected to three simulated below-system infiltration rates for two growing seasons. Infiltration rate affected both transpiration and rooting depth. In a factorial experiment with ash, rooting depth always increased with infiltration rate for Stalite, but this relation was less consistent for CUSoil. Slow-drainage rates reduced transpiration and restricted rooting depth for both species and soils, and trunk growth was restricted for oak, which grew the most in moderate infiltration. Transpiration rates under slow infiltration were 55% (oak) and 70% (ash) of the most rapidly transpiring treatment (moderate for oak and rapid for ash). We conclude this system is feasible and provides another tool to address runoff that integrates the function of urban green spaces with other urban needs. PMID:19707704

  2. Transpiration affects soil CO2 production in a dry grassland

    NASA Astrophysics Data System (ADS)

    Balogh, János; Fóti, Szilvia; Pintér, Krisztina; Burri, Susanne; Eugster, Werner; Papp, Marianna; Nagy, Zoltán

    2014-05-01

    Although soil CO2 efflux can be highly variable on the diel time scale, it is often measured during daytime only. However, to get a full understanding of soil CO2 efflux and its impact on carbon cycle processes, looking at diurnal processes is crucial. Therefore, our aim was to investigate how diel variation in soil CO2 efflux from a dry, sandy grassland in Hungary depends on variations in potential drivers, such as gross primary production (GPP) and evapotranspiration (ET). In order to reach this goal, we combined measurements of CO2 and H2O fluxes by eddy covariance, soil chambers and soil CO2 gradient system. Surface CO2 fluxes were partitioned into the three CO2 production components originating from the three soil layers to clarify the timing and the source of the CO2 within the top 50 cm of the soil. CO2 production rates during the growing season were higher during nighttime than during daytime. This diel course was not only driven by soil temperature and soil moisture, but also by ET. This was shown by changes of ET causing a hysteresis loop in the diel response of CO2 production to soil temperature. CO2 production was coupled to soil temperature at night and during midday (12-14 h), when ET remained relatively constant. However, when ET was changing over time, CO2 production was decoupled from soil temperature. In order to disentangle these effects, we carried out time-lag analyses between CO2 production and efflux residuals after having subtracted the main effects of soil temperature and soil water content from measured CO2 fluxes. The results showed a strong negative correlation between ET rates and residuals of soil CO2 production, and a less strong, but still significantly time-lagged positive correlation between GPP and residuals of soil CO2 production. Thus, we could show that there is a rapid negative response of soil CO2 production rates to transpiration (suggesting CO2 transport in the xylem stream) and a delayed positive response to GPP, indicating the importance of newly synthesized non-structural carbohydrates for soil respiration. We conclude that the instant effect of soil temperature and transpiration in combination with the time-lagged effect of GPP governed the diel changes in soil CO2 production at our site. If measurements are carried out at night or during daytime only, then this can lead to considerable misinterpretations of CO2 production rates. Hence we recommend that estimates of respiration rates at a specific site should include both nocturnal and daytime processes.

  3. Comparison of test results for flat plate, transpired flat plate, corrugated, and transpired corrugated solar air heaters

    NASA Astrophysics Data System (ADS)

    Rhee, S. J.; Edwards, D. K.

    1981-11-01

    Results from tests to demonstrate technical improvements from transpiring and/or corrugating a selective black absorber plate solar air collector are reported. A literature review is presented, and the specific working components of transpired and nontranspired flat and corrugated absorbers are provided, including transpiration through slots, a microperforated plate, a corrugated plate, and a transpired, slotted, corrugated plate. Inlet and outlet temperatures were monitored, and inlet air was controlled, with trials covering temperatures of 38, 60, 82, and 104 C to test the effect of maintaining the fluid temperature close to the collector temperature. No differences were observed in running the collectors with corrugations vertically instead of horizontally, and the collector with transpiration through slots was found to display the lowest pressure drop.

  4. A comparison of calibrated sap flow and MAESTRA model simulation estimates of tree transpiration in a Eucalyptus plantation

    NASA Astrophysics Data System (ADS)

    Campoe, O. C.; Rojas, J.; Stape, J.; Laclau, J.; Le Maire, G.; Bauerle, W.; Marsden, C.; Nouvellon, Y.

    2010-12-01

    We examined the ability of the MAESTRA model, a three dimensional model of individual tree transpiration, to capture the seasonal and within-stand tree water-use variability in a fast-growing eucalyptus plantation. MAESTRA was parameterized using data from in situ measurements on tree organs. To capture within-stand variability in tree size, sap flow measurements were taken on 15 trees that spanned the range in aboveground biomass (16.3 - 346.2 kg) and leaf area (2.1 - 90.1 m2) in a 6 year old southeast Brazil Eucalyptus grandis plantation. Transpiration simulation predictions were compared to estimates from sap flow measured by the thermal dissipation method calibrated at the whole tree (potometer) and stand (eddy covariance) level. Calculated transpiration showed a significant relationship to measured transpiration (R2=0.79, p<0.0001, Figure 1). During the study, measured and simulated transpiration rates ranged from 2.6 to 92.7 L day-1 and 2.1 to 110.4 L day-1, respectively, whereas mean maximum and minimum temperature were 20.3, 33.2 and 16 oC, respectively, and total precipitation was 1148mm. Seasonal differences between measured and modeled maximum (46.5 versus 65.7 L day-1), mean (30.7 versus 34.1 L day-1) and minimum (17.6 versus 16.1 L day-1) transpiration were small. Specific to within-stand variability in tree size, MAESTRA underestimated the transpiration of small trees (leaf area < 15m2) by 8% and overestimated large trees (leaf area > 45 m2) by 9%. This work quantified the accuracy of the MAESTRA model to estimate seasonal patterns of Eucalyptus grandis forest plantation transpiration. Hence, MAESTRA can assess the consequence of Eucalyptus grandis production on the hydrologic resources of the region. Figure 1. Relation between measured and modeled transpiration rates for all trees and days. Dashed line represents 1:1 line.

  5. Design of Transpiration Cooled Thermal Protection Systems

    NASA Technical Reports Server (NTRS)

    Callens, E. Eugene, Jr.; Vinet, Robert F.

    1999-01-01

    This study explored three approaches for the utilization of transpiration cooling in thermal protection systems. One model uses an impermeable wall with boiling water heat transfer at the backface (Model I). A second model uses a permeable wall with a boiling water backface and additional heat transfer to the water vapor as it flows in channels toward the exposed surface (Model II). The third model also uses a permeable wall, but maintains a boiling condition at the exposed surface of the material (Model III). The governing equations for the models were developed in non-dimensional form and a comprehensive parametric investigation of the effects of the independent variables on the important dependent variables was performed. In addition, detailed analyses were performed for selected materials to evaluate the practical limitations of the results of the parametric study.

  6. Transpiration efficiency over an annual cycle, leaf gas exchange and wood carbon isotope ratio of three tropical tree species.

    PubMed

    Cernusak, Lucas A; Winter, Klaus; Aranda, Jorge; Virgo, Aurelio; Garcia, Milton

    2009-09-01

    Variation in transpiration efficiency (TE) and its relationship with the stable carbon isotope ratio of wood was investigated in the saplings of three tropical tree species. Five individuals each of Platymiscium pinnatum (Jacq.) Dugand, Swietenia macrophylla King and Tectona grandis Linn. f. were grown individually in large (760 l) pots over 16 months in the Republic of Panama. Cumulative transpiration was determined by repeatedly weighing the pots with a pallet truck scale. Dry matter production was determined by destructive harvest. The TE, expressed as experiment-long dry matter production divided by cumulative water use, averaged 4.1, 4.3 and 2.9 g dry matter kg(-1) water for P. pinnatum, S. macrophylla and T. grandis, respectively. The TE of T. grandis was significantly lower than that of the other two species. Instantaneous measurements of the ratio of intercellular to ambient CO(2) partial pressures (c(i)/c(a)), taken near the end of the experiment, explained 66% of variation in TE. Stomatal conductance was lower in S. macrophylla than in T. grandis, whereas P. pinnatum had similar stomatal conductance to T. grandis, but with a higher photosynthetic rate. Thus, c(i)/c(a) and TE appeared to vary in response to both stomatal conductance and photosynthetic capacity. Stem-wood delta(13)C varied over a relatively narrow range of just 2.2 per thousand, but still explained 28% of variation in TE. The results suggest that leaf-level processes largely determined variation among the three tropical tree species in whole-plant water-use efficiency integrated over a full annual cycle. PMID:19661136

  7. Arsenite toxicity and uptake rate of rice ( Oryza sativa L.) in vivo

    Microsoft Academic Search

    Holger Hoffmann; Manfred K. Schenk

    2011-01-01

    Toxicity threshold of arsenite on intact rice seedlings was determined and arsenite uptake characteristics were investigated using non-toxic concentrations of arsenite.The arsenite toxicity threshold was 2.4?M arsenite which reduced growth by 10% (EC10). The two highest arsenite levels induced wilting of seedlings and reduced both, transpiration rate and net photosynthetic rate. Arsenic content in plant tissue increased up to 10.7?M

  8. From Plants to Birds: Higher Avian Predation Rates in Trees Responding to Insect Herbivory

    E-print Network

    Laaksonen, Toni

    From Plants to Birds: Higher Avian Predation Rates in Trees Responding to Insect Herbivory Elina Ma: An understanding of the evolution of potential signals from plants to the predators of their herbivores may provide the attraction of predators to plants is crucial to conclusions about co-evolution. For example, insectivorous

  9. Relationship between Hexokinase and the Aquaporin PIP1 in the Regulation of Photosynthesis and Plant Growth

    PubMed Central

    Kelly, Gilor; Sade, Nir; Attia, Ziv; Secchi, Francesca; Zwieniecki, Maciej; Holbrook, N. Michele; Levi, Asher; Alchanatis, Victor; Moshelion, Menachem; Granot, David

    2014-01-01

    Increased expression of the aquaporin NtAQP1, which is known to function as a plasmalemma channel for CO2 and water, increases the rate of both photosynthesis and transpiration. In contrast, increased expression of Arabidopsis hexokinase1 (AtHXK1), a dual-function enzyme that mediates sugar sensing, decreases the expression of photosynthetic genes and the rate of transpiration and inhibits growth. Here, we show that AtHXK1 also decreases root and stem hydraulic conductivity and leaf mesophyll CO2 conductance (gm). Due to their opposite effects on plant development and physiology, we examined the relationship between NtAQP1 and AtHXK1 at the whole-plant level using transgenic tomato plants expressing both genes simultaneously. NtAQP1 significantly improved growth and increased the transpiration rates of AtHXK1-expressing plants. Reciprocal grafting experiments indicated that this complementation occurs when both genes are expressed simultaneously in the shoot. Yet, NtAQP1 had only a marginal effect on the hydraulic conductivity of the double-transgenic plants, suggesting that the complementary effect of NtAQP1 is unrelated to shoot water transport. Rather, NtAQP1 significantly increased leaf mesophyll CO2 conductance and enhanced the rate of photosynthesis, suggesting that NtAQP1 facilitated the growth of the double-transgenic plants by enhancing mesophyll conductance of CO2. PMID:24498392

  10. Impact of planting date and seeding rate on grain and forage yields of wheat in Texas

    E-print Network

    Shaffer, Oliver Jacob

    2009-05-15

    yields. Results and Discussion Spike Density In the 2004/2005 season, the number of tillers developing harvestable heads was not different among any of the seeding rates or planting dates (PD) (Figure 2). When all seeding rates were averaged..., PD 5 produced more harvestable heads than planting dates 1, 2, and 3. Mean spike density of planting dates 1, 2, and 3 were similar. Planting date 6 produced 50% fewer heads than all other planting dates. This agrees with a Kansas state study which...

  11. Isotopic steady state of transpired water in wheat leaves grown under different watering regimes

    NASA Astrophysics Data System (ADS)

    Hu, J.; Simonin, K.; Barbour, M.

    2013-12-01

    Stable oxygen isotopes have been used to answer a range of ecological, hydrological, and climate questions. One important application is to use oxygen isotopes to partition ecosystem evapotranspiration (ET), since the two components, transpiration and evaporation have distinctly different isotopic compositions (?18O). However, in order to partition ET using isotopes, accurate measurements or modeling of evaporation and transpiration, are needed. Many studies use the Craig-Gordon Model to model the isotopic composition of transpired water (?18OT), which assume plants are transpiring at isotopic steady state (ISS), such that the isotopic composition of transpired water (?18OT) is equal to the ?18O of stem water. However, many studies are questioning the assumption that plants are transpiring at ISS, especially across diurnal time scales. A significant motivation for assuming ISS is the difficulty of collecting transpired water for isotopic analysis. However, with the introduction of laser based spectroscopy methods for isotope analysis, we can now measure ?18O of water vapor at high frequency. Furthermore, these laser based instruments can also be coupled with gas exchange systems to not only measure the isotopic composition of ?18OT, but also to examine the physiological and environmental variables that influence the isotope values, and directly test process-based models. In our study, our first objective was to assess how quickly plants reached isotopic constancy (IC) under a range of environmental conditions. We used two different wheat cultivars that had different stomatal conductance (gs) and subjected them to two different watering treatments to extend the range of gs. Our second objective was to compare ?18OT at IC with ?18O of irrigation water to understand the difference between ISS and IC. We found a significant positive relationship between gs and time to IC (p<0.003, R2 = 0.78) and that the time ranged from 20 to 205 minutes. In order to further confirm that the leaves were at IC and that changes ?18OT values were not due to turnover of leaf water, we also calculated the leaf water turner time constant (?). We found that ? ranged from 12 minutes to 97 minutes and since ? values were less than IC values, we were confident our ?18OT values were at IC. Furthermore, our results found that even at IC, ?18OT never equaled the ?18O of irrigation water; in other words, ?18OT never reached ISS. This has implications for ecosystem scale studies that use oxygen isotopes to partition ET since in most of these studies, ?18OT was not directly measured, but ?18OT was assumed to equal ?18O of xylem water. Incorrect assumptions of ?18OT may lead to differences in the percentage of transpiration versus evaporation. New sensitivity analysis at the ecosystem scale is needed to quantify the potential errors.

  12. Water Balance in Terrestrial PlantsWater Balance in Terrestrial Plants Water Regulation on LandWater Regulation on Land --PlantsPlants WWipip= W= Wrr + W+ Waa --WWtt --WWss

    E-print Network

    Cochran-Stafira, D. Liane

    1 Water Balance in Terrestrial PlantsWater Balance in Terrestrial Plants Water Regulation on LandWater waters internal water WWrr =Roots=Roots WWaa = Air= Air WWtt = Transpiration= Transpiration WWss = Secretions= Secretions Water Regulation on Land - Plants Water Balance in Terrestrial PlantsWater Balance

  13. Implications of Advanced Crew Escape Suit Transpiration for the Orion Program

    NASA Technical Reports Server (NTRS)

    Bue, Grant; Kuznetz, Lawrence

    2009-01-01

    Human testing was conducted to more fully characterize the integrated performance of the Advanced Crew Escape Suit (ACES) with liquid cooling provide by an Individual Cooling Unit (ICU) across a broad range of environmental conditions and metabolic rates. Together with a correlation for the ACES Liquid Cooling Garment as a function of inlet temperature, metabolic rate, and crew size, a reasonably conservative correlation for core temperature was achieved for the human thermal model applied to the ACES with ICU cooling. A key observation for this correlation was accounting for transpiration of evaporated sweat through the Gortex(Registered TradeMark) liner of the ACES indicated by as much as 0.6 lbm of sweat evaporated over the course of the 1 hour test profile, most of which could not be attributed to respiration or head sweat evaporation of the crew. Historically it has been assumed that transpiration was not an important design feature of the ACES suit. The correlated human thermal model will show transpiration to be highly useful in hot survival situations for the Orion Program when adequate liquid cooling is not available.

  14. When do plants modify fluvial processes? Plant-hydraulic interactions under variable flow and sediment supply rates

    NASA Astrophysics Data System (ADS)

    Manners, Rebecca B.; Wilcox, Andrew C.; Kui, Li; Lightbody, Anne F.; Stella, John C.; Sklar, Leonard S.

    2015-02-01

    Flow and sediment regimes shape alluvial river channels; yet the influence of these abiotic drivers can be strongly mediated by biotic factors such as the size and density of riparian vegetation. We present results from an experiment designed to identify when plants control fluvial processes and to investigate the sensitivity of fluvial processes to changes in plant characteristics versus changes in flow rate or sediment supply. Live seedlings of two species with distinct morphologies, tamarisk (Tamarix spp.) and cottonwood (Populus fremontii), were placed in different configurations in a mobile sand-bed flume. We measured the hydraulic and sediment flux responses of the channel at different flow rates and sediment supply conditions representing equilibrium (sediment supply = transport rate) and deficit (sediment supply < transport rate). We found that the hydraulic and sediment flux responses during sediment equilibrium represented a balance between abiotic and biotic factors and was sensitive to increasing flow rates and plant species and configuration. Species-specific traits controlled the hydraulic response: compared to cottonwood, which has a more tree-like morphology, the shrubby morphology of tamarisk resulted in less pronation and greater reductions in near-bed velocities, Reynolds stress, and sediment flux rates. Under sediment-deficit conditions, on the other hand, abiotic factors dampened the effect of variations in plant characteristics on the hydraulic response. We identified scenarios for which the highest stem-density patch, independent of abiotic factors, dominated the fluvial response. These results provide insight into how and when plants influence fluvial processes in natural systems.

  15. Recently Formed Polyploid Plants Diversify at Lower Rates

    Microsoft Academic Search

    Itay Mayrose; Shing H. Zhan; Carl J. Rothfels; Karen Magnuson-Ford; Michael S. Barker; Loren H. Rieseberg; Sarah P. Otto

    2011-01-01

    Polyploidy, the doubling of genomic content, is a widespread feature, especially among plants, yet its macroevolutionary impacts are contentious. Traditionally, polyploidy has been considered an evolutionary dead end, whereas recent genomic studies suggest that polyploidy has been a key driver of macroevolutionary success. We examined the consequences of polyploidy on the time scale of genera across a diverse set of

  16. Venezuelan extraction plant expanding to 1 bcfd rating

    SciTech Connect

    Jimenez-Gomez, H. (Corpoven S.A., San Joaquin (VE))

    1990-12-03

    This paper discusses how modification of the two process trains at Corpoven's San Joaquin, Venezuela, extraction plant will increase each train's sustained capacity to 500 MMscfd and 1 bcfd total plant capacity. The San Joaquin 1000 project, set for completion in 1991, will represent an increase in NGL production of 8,000 b/d, with a gross revenue of $25 million/year for Corpoven S.A., a subsidiary of Petroleos de Venezuela. The San Joaquin extraction plant currently consists of two identical process trains, each designed to handle 400 MMscfd of rich gas. Original design also provided for future conversion for 70% ethane recovery with the installation of CO{sub 2}-removal units for the inlet gas. Because actual inlet gas has been much leaner than design, and excess capacity has existed in some vessels resulting from considerations for the 70% ethane-recovery case, true capacity of the plant is considerably higher than design. In addition, stream tests have shown peak processing capacity approaching 500 MMscfd/train.

  17. The importance of micrometeorological variations for photosynthesis and transpiration in a boreal coniferous forest

    NASA Astrophysics Data System (ADS)

    Schurgers, G.; Lagergren, F.; Mölder, M.; Lindroth, A.

    2015-01-01

    Plant canopies affect the canopy micrometeorology, and thereby alter canopy exchange processes. For the simulation of these exchange processes on a regional or global scale, large-scale vegetation models often assume homogeneous environmental conditions within the canopy. In this study, we address the importance of vertical variations in light, temperature, CO2 concentration and humidity within the canopy for fluxes of photosynthesis and transpiration of a boreal coniferous forest in central Sweden. A leaf-level photosynthesis-stomatal conductance model was used for aggregating these processes to canopy level while applying the within-canopy distributions of these driving variables. The simulation model showed good agreement with eddy covariance-derived gross primary production (GPP) estimates on daily and annual timescales, and showed a reasonable agreement between transpiration and observed H2O fluxes, where discrepancies are largely attributable to a lack of forest floor evaporation in the model. Simulations in which vertical heterogeneity was artificially suppressed revealed that the vertical distribution of light is the driver of vertical heterogeneity. Despite large differences between above-canopy and within-canopy humidity, and despite large gradients in CO2 concentration during early morning hours after nights with stable conditions, neither humidity nor CO2 played an important role for vertical heterogeneity of photosynthesis and transpiration.

  18. The importance of micrometeorological variations for photosynthesis and transpiration in a boreal coniferous forest

    NASA Astrophysics Data System (ADS)

    Schurgers, G.; Lagergren, F.; Mölder, M.; Lindroth, A.

    2014-08-01

    Plant canopies affect the canopy micrometeorology, and thereby alter canopy exchange processes. For the simulation of these exchange processes on a regional or global scale, large-scale vegetation models often assume homogeneous environmental conditions within the canopy. In this study, we address the importance of vertical variations in light, temperature, CO2 concentration and humidity within the canopy for photosynthesis and transpiration of a boreal coniferous forest in central Sweden. A leaf-level photosynthesis-stomatal conductance model was used for aggregating these processes to canopy level while applying the within-canopy distributions of these driving variables. The simulation model showed good agreement with eddy covariance-derived gross primary production (GPP) estimates on daily and annual timescales, and showed a reasonable agreement between transpiration and observed H2O fluxes, where discrepancies are largely attributable to a lack of forest floor evaporation in the model. Simulations in which vertical heterogeneity was artificially suppressed revealed that the vertical distribution of light is the driver of vertical heterogeneity. Despite large differences between above-canopy and within canopy humidity, and despite large gradients in CO2 concentration during early morning hours after nights with stable conditions, neither humidity nor CO2 played an important role for vertical heterogeneity of photosynthesis and transpiration.

  19. The effect of wind velocity on transpiration in a mixed broadleaved deciduous forest

    NASA Astrophysics Data System (ADS)

    Kim, D.; Oren, R.; Oishi, A. C.; Hsieh, C.; Phillips, N. G.; Novick, K. A.; Stoy, P. C.

    2013-12-01

    Wind velocity (U) within and above forest canopies can alter the coupling between the vapor-saturated sub-stomatal airspace and the drier atmosphere aloft, thereby influencing transpiration rates. In practice, however, the actual increase in transpiration with increasing U depends on the aerodynamic resistance (RA) to vapor transfer compared to canopy resistance to water vapor flux out of leaves (RC, dominated by stomatal resistance, Rstom), and the rate at which RA decreases with increasing U. We investigated the effect of U on transpiration at the canopy scale using filtered meteorological data and sap flux measurements gathered from six diverse species of a mature broadleaved deciduous forest. Only under high light conditions, stand transpiration (EC) increased slightly (6.5%) with increasing U ranging from ~0.7 to ~4.7 m s-1. Under other conditions, sap flux density (Js) and EC responded weakly or did not change with U. RA, estimated from Monin-Obukhov similarity theory, decreased with increasing U, but this decline was offset by increasing RC, estimated from a rearranged Penman-Monteith equation, due to a concurrent increase in vapor pressure deficit (D). The increase of RC with D over the observed range of U was consistent with increased Rstom by ~40% based on hydraulic theory. Except for very rare half-hourly values, the proportion of RA to total resistance (RT) remained < 15% over the observed range of conditions. These results suggest that in similar forests and conditions, accounting for the effects of U-D relationship on Rstom would reduce the uncertainty of modeling canopy gas exchange more than accounting for the direct effect of U on RA.

  20. Canopy Transpiration in a Chronosequence of Central Siberian Pine Forests

    NASA Technical Reports Server (NTRS)

    Reiner, Z.; Ernst-Detler, S.; Christian, W.; Ernst-Eckart, S.; Waldemar, Z.

    1998-01-01

    Tree transpiration was measured in 28, 67, 204 and 383 - year old uniform stands and in a multi-cohort stand (140 t0 430) of Pinus sylvestris ssp. sibirica Lebed. in Central Siberia during August of 1995.

  1. Leaf transpiration efficiency of some drought-resistant maize lines

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Field measurements of leaf gas exchange in maize often indicate stomatal conductances higher than required to provide substomatal carbon dioxide concentrations saturating to photosynthesis. Thus maize leaves often operate at lower transpiration efficiency (TE) than potentially achievable for specie...

  2. Numerical Simulation Study on Transpired Solar Air Collector

    E-print Network

    Wang, C.; Guan, Z.; Zhao, X.; Wang, D.

    2006-01-01

    The unglazed transpired solar air collector is now a well-recognized solar air heater for heating outside air directly. In this article, researchers introduced numerical simulation tools into the solar air collector research area, analyzed...

  3. Biological and environmental controls on tree transpiration in a suburban landscape

    NASA Astrophysics Data System (ADS)

    Peters, Emily B.; McFadden, Joseph P.; Montgomery, Rebecca A.

    2010-12-01

    Tree transpiration provides a variety of ecosystem services in urban areas, including amelioration of urban heat island effects and storm water management. Tree species vary in the magnitude and seasonality of transpiration owing to differences in physiology, response to climate, and biophysical characteristics, thereby complicating efforts to manage evapotranspiration at city scales. We report sap flux measurements during the 2007 and 2008 growing seasons for dominant tree species in a suburban neighborhood of Minneapolis-Saint Paul, Minnesota, USA. Evergreen needleleaf trees had significantly higher growing season means and annual transpiration per unit canopy area (1.90 kg H2O m-2 d-1 and 307 kg H2O m-2 yr-1, respectively) than deciduous broadleaf trees (1.11 kg H2O m-2 d-1 and 153 kg H2O m-2 yr-1, respectively) because of a smaller projected canopy area (31.1 and 73.6 m2, respectively), a higher leaf area index (8.8 and 5.5 m2 m-2, respectively), and a longer growth season (8 and 4 months, respectively). Measurements also showed patterns consistent with the species' differences in xylem anatomy (conifer, ring porous, and diffuse porous). As the growing season progressed, conifer and diffuse porous genera had increased stomatal regulation to high vapor pressure deficit, while ring porous genera maintained greater and more constant stomatal regulation. These results suggest that evaporative responses to climate change in urban ecosystems will depend in part on species composition. Overall, plant functional type differences in canopy structure and growing season length were most important in explaining species' differences in midsummer and annual transpiration, offering an approach to predicting the evapotranspiration component of urban water budgets.

  4. Plant Disease / October 2001 1113 Effect of Host Plant Resistance and Reduced Rates and Frequencies

    E-print Network

    Douches, David S.

    of Fungicide Application to Control Potato Late Blight W. W. Kirk, Department of Plant Pathology; K. J. Felcher, D. S. Douches, and J. Coombs, Department of Crop and Soil Sciences; J. M. Stein, Department of Plant Pathology; K. M. Baker, Department of Geography; and R. Hammerschmidt, Department of Plant Pathology

  5. Transpiration during life cycle in controlled wheat growth

    NASA Technical Reports Server (NTRS)

    Volk, Tyler; Rummel, John D.

    1990-01-01

    A previously developed model of wheat growth, designed for convenient incorporation into system level models of advanced space life support systems is described. The model is applied to data from an experiment that grew wheat under controlled conditions and measured fresh biomass and cumulated transpiration as a function of time. The adequacy of modeling the transpiration as proportional to the inedible biomass and an age factor that varies during the life cycle are discussed.

  6. Overproduction of Abscisic Acid in Tomato Increases Transpiration Efficiency and Root Hydraulic Conductivity and Influences Leaf Expansion1[OA

    PubMed Central

    Thompson, Andrew J.; Andrews, John; Mulholland, Barry J.; McKee, John M.T.; Hilton, Howard W.; Horridge, Jon S.; Farquhar, Graham D.; Smeeton, Rachel C.; Smillie, Ian R.A.; Black, Colin R.; Taylor, Ian B.

    2007-01-01

    Overexpression of genes that respond to drought stress is a seemingly attractive approach for improving drought resistance in crops. However, the consequences for both water-use efficiency and productivity must be considered if agronomic utility is sought. Here, we characterize two tomato (Solanum lycopersicum) lines (sp12 and sp5) that overexpress a gene encoding 9-cis-epoxycarotenoid dioxygenase, the enzyme that catalyzes a key rate-limiting step in abscisic acid (ABA) biosynthesis. Both lines contained more ABA than the wild type, with sp5 accumulating more than sp12. Both had higher transpiration efficiency because of their lower stomatal conductance, as demonstrated by increases in ?13C and ?18O, and also by gravimetric and gas-exchange methods. They also had greater root hydraulic conductivity. Under well-watered glasshouse conditions, mature sp5 plants were found to have a shoot biomass equal to the wild type despite their lower assimilation rate per unit leaf area. These plants also had longer petioles, larger leaf area, increased specific leaf area, and reduced leaf epinasty. When exposed to root-zone water deficits, line sp12 showed an increase in xylem ABA concentration and a reduction in stomatal conductance to the same final levels as the wild type, but from a different basal level. Indeed, the main difference between the high ABA plants and the wild type was their performance under well-watered conditions: the former conserved soil water by limiting maximum stomatal conductance per unit leaf area, but also, at least in the case of sp5, developed a canopy more suited to light interception, maximizing assimilation per plant, possibly due to improved turgor or suppression of epinasty. PMID:17277097

  7. Plant Diversity: Effects of Grazing System and Stocking Rate in Northern Mixed-Grass Prairie

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Effects of grazing system, stocking rate, and grazing system X stocking rate interactions, on plant diversity are poorly understood in rangelands. A grazing system (season-long and short-duration rotational grazing) X stocking rate (light: 16 steers•80 ha-1, moderate: 4 steers•12 ha-1 and heavy: 4 s...

  8. Glutathione and transpiration as key factors conditioning oxidative stress in Arabidopsis thaliana exposed to uranium.

    PubMed

    Aranjuelo, Iker; Doustaly, Fany; Cela, Jana; Porcel, Rosa; Müller, Maren; Aroca, Ricardo; Munné-Bosch, Sergi; Bourguignon, Jacques

    2014-04-01

    Although oxidative stress has been previously described in plants exposed to uranium (U), some uncertainty remains about the role of glutathione and tocopherol availability in the different responsiveness of plants to photo-oxidative damage. Moreover, in most cases, little consideration is given to the role of water transport in shoot heavy metal accumulation. Here, we investigated the effect of uranyl nitrate exposure (50 ?M) on PSII and parameters involved in water transport (leaf transpiration and aquaporin gene expression) of Arabidopsis wild type (WT) and mutant plants that are deficient in tocopherol (vte1: null ?/?-tocopherol and vte4: null ?-tocopherol) and glutathione biosynthesis (high content: cad1.3 and low content: cad2.1). We show how U exposure induced photosynthetic inhibition that entailed an electron sink/source imbalance that caused PSII photoinhibition in the mutants. The WT was the only line where U did not damage PSII. The increase in energy thermal dissipation observed in all the plants exposed to U did not avoid photo-oxidative damage of mutants. The maintenance of control of glutathione and malondialdehyde contents probed to be target points for the overcoming of photoinhibition in the WT. The relationship between leaf U content and leaf transpiration confirmed the relevance of water transport in heavy metals partitioning and accumulation in leaves, with the consequent implication of susceptibility to oxidative stress. PMID:24389672

  9. Transpired solar air heaters. Volume 1. Investigation of transpired porous-bed solar air heaters. Final report

    Microsoft Academic Search

    Galanter

    1980-01-01

    Tests were conducted to determine the thermal performance of a number of transpired porous-bed solar air heaters. Improvements were made to a reference double-glazed transpired solar air heater and the performance experimentally determined. An air heater incorporating two parallel glass-plate honeycombs for air heater incorporating two parallel glass-plate honeycombs for heat-loss control was also tested. The performance of the double-honeycomb

  10. Power conditioning options for central station rated photovoltaic power plants

    Microsoft Academic Search

    T. S. Key; F. G. Turnbull

    1985-01-01

    Design options for power conditioning in a 5 megawatt photovoltaic power station include the use of a small number of high-power modules, or a larger number of low-power modules. The effects of this choice on Power Conditioning Subsystem (PCS) cost, efficiency, and overall design are discussed, based on experience gained from recent inverter design studies for power ratings ranging from

  11. Transpiration efficiency: new insights into an old story.

    PubMed

    Vadez, Vincent; Kholova, Jana; Medina, Susan; Kakkera, Aparna; Anderberg, Hanna

    2014-11-01

    Producing more food per unit of water has never been as important as it is at present, and the demand for water by economic sectors other than agriculture will necessarily put a great deal of pressure on a dwindling resource, leading to a call for increases in the productivity of water in agriculture. This topic has been given high priority in the research agenda for the last 30 years, but with the exception of a few specific cases, such as water-use-efficient wheat in Australia, breeding crops for water-use efficiency has yet to be accomplished. Here, we review the efforts to harness transpiration efficiency (TE); that is, the genetic component of water-use efficiency. As TE is difficult to measure, especially in the field, evaluations of TE have relied mostly on surrogate traits, although this has most likely resulted in over-dependence on the surrogates. A new lysimetric method for assessing TE gravimetrically throughout the entire cropping cycle has revealed high genetic variation in different cereals and legumes. Across species, water regimes, and a wide range of genotypes, this method has clearly established an absence of relationships between TE and total water use, which dismisses previous claims that high TE may lead to a lower production potential. More excitingly, a tight link has been found between these large differences in TE in several crops and attributes of plants that make them restrict water losses under high vapour-pressure deficits. This trait provides new insight into the genetics of TE, especially from the perspective of plant hydraulics, probably with close involvement of aquaporins, and opens new possibilities for achieving genetic gains via breeding focused on this trait. Last but not least, small amounts of water used in specific periods of the crop cycle, such as during grain filling, may be critical. We assessed the efficiency of water use at these critical stages. PMID:24600020

  12. Physiological studies in young Eucalyptus stands in southern India and their use in estimating forest transpiration

    SciTech Connect

    Roberts, J.M.; Rosier, P.T.W. [Inst. of Hydrology, Wallingford (United Kingdom); Murthy, K.V. [Mysore Paper Mills, Shimoga (India)

    1992-12-31

    Stomatal conductance, leaf water potential and leaf area index were measured in adjacent plantations of Eucalyptus camaldulensis and Eucalyptus tereticornis at Puradal, near Shimoga, Karnataka, southern India. The data were collected in a range of climatic conditions during a two year period immediately following plantation establishment. Physiological differences between the two species were small and confined largely to leaf area index. Stomatal conductance was highest in the post-monsoon period and declined to minimum values immediately prior to the onset of the monsoon, with the lowest conductances observed after the plantations had been established for more than one year. Stomatal conductance, leaf area index and above-canopy meteorological data were combined in a multi-layer transpiration model and used to calculate hourly values of transpiration from the two species. Rates of transpiration up to 6 mm d{sup {minus}1} were estimated for the post-monsoon period but fell to below 1 mm d{sup {minus}1} prior to the monsoon.

  13. Measurements of transpiration isotopologues and leaf water to assess enrichment models in cotton.

    PubMed

    Song, Xin; Loucos, Karen E; Simonin, Kevin A; Farquhar, Graham D; Barbour, Margaret M

    2015-04-01

    The two-pool and Péclet effect models represent two theories describing mechanistic controls underlying leaf water oxygen isotope composition at the whole-leaf level (?(18) OL ). To test these models, we used a laser spectrometer coupled to a gas-exchange cuvette to make online measurements of ?(18) O of transpiration (?(18) Otrans ) and transpiration rate (E) in 61 cotton (Gossypium hirsutum) leaves. ?(18) Otrans measurements permitted direct calculation of ?(18) O at the sites of evaporation (?(18) Oe ) which, combined with values of ?(18) OL from the same leaves, allowed unbiased estimation of the proportional deviation of enrichment of ?(18) OL from that of ?(18) Oe (f) under both steady-state (SS) and non-steady-state (NSS) conditions. Among all leaves measured, f expressed relative to both ?(18) O of transpired water (ftrans ) and source water (fsw ) remained relatively constant with a mean ± SD of 0.11 ± 0.05 and 0.13 ± 0.05, respectively, regardless of variation in E spanning 0.8-9.1 mmol m(-2)  s(-1) . Neither ftrans nor fsw exhibited a significant difference between the SS and NSS leaves at the P < 0.05 level. Our results suggest that the simpler two-pool model is adequate for predicting cotton leaf water enrichment at the whole-leaf level. We discuss the implications of adopting a two-pool concept for isotopic applications in ecological studies. PMID:25643590

  14. HESS Opinions "A perspective on isotope versus non-isotope approaches to determine the contribution of transpiration to total evaporation"

    NASA Astrophysics Data System (ADS)

    Sutanto, S. J.; van den Hurk, B.; Dirmeyer, P. A.; Seneviratne, S. I.; Röckmann, T.; Trenberth, K. E.; Blyth, E. M.; Wenninger, J.; Hoffmann, G.

    2014-08-01

    Current techniques to disentangle the evaporative fluxes from the continental surface into a contribution evaporated from soils and canopy, or transpired by plants, are under debate. Many isotope-based studies show that transpiration contributes generally more than 70% to the total evaporation, while other isotope-independent techniques lead to considerably smaller transpiration fractions. This paper provides a perspective on isotope-based versus non-isotope-based partitioning studies. Some partitioning results from isotope-based methods, hydrometric measurements, and modeling are presented for comparison. Moreover, the methodological aspects of the partitioning analysis are considered, including their limitations, and explanations of possible discrepancies between the methods are discussed. We suggest sources of systematic error that may lead to biases in the results, e.g., instruments inaccuracy, assumptions used in analyses, and calibration parameters. A number of comparison studies using isotope-based methods and hydrometric measurements in the same plants and climatic conditions are consistent within the errors; however, models tend to produce lower transpiration fractions. The relatively low transpiration fraction in current state-of-the-art land-surface models calls for a reassessment of the skill of the underlying model parameterizations. The scarcity of global evaporation data makes calibration and validation of global isotope-independent and isotope-based results difficult. However, isotope-enabled land-surface and global climate modeling studies allow for the evaluation of the parameterization of land-surface models by comparing the computed water isotopologue signals in the atmosphere with the available remote sensing and flux-based data sets. Future studies that allow for this evaluation could provide a better understanding of the hydrological cycle in vegetated regions.

  15. Response of transpiration to rain pulses for two tree species in a semiarid plantation.

    PubMed

    Chen, Lixin; Zhang, Zhiqiang; Zeppel, Melanie; Liu, Caifeng; Guo, Junting; Zhu, Jinzhao; Zhang, Xuepei; Zhang, Jianjun; Zha, Tonggang

    2014-09-01

    Responses of transpiration (Ec) to rain pulses are presented for two semiarid tree species in a stand of Pinus tabulaeformis and Robinia pseudoacacia. Our objectives are to investigate (1) the environmental control over the stand transpiration after rainfall by analyzing the effect of vapor pressure deficit (VPD), soil water condition, and rainfall on the post-rainfall Ec development and recovery rate, and (2) the species responses to rain pulses and implications on vegetation coverage under a changing rainfall regime. Results showed that the sensitivity of canopy conductance (Gc) to VPD varied under different incident radiation and soil water conditions, and the two species exhibited the same hydraulic control (-dG c/dlnVPD to Gcref ratio) over transpiration. Strengthened physiological control and low sapwood area of the stand contributed to low Ec. VPD after rainfall significantly influenced the magnitude and time series of post-rainfall stand Ec. The fluctuation of post-rainfall VPD in comparison with the pre-rainfall influenced the Ec recovery. Further, the stand Ec was significantly related to monthly rainfall, but the recovery was independent of the rainfall event size. Ec enhanced with cumulative soil moisture change (?VWC) within each dry-wet cycle, yet still was limited in large rainfall months. The two species had different response patterns of post-rainfall Ec recovery. Ec recovery of P. tabulaeformis was influenced by the pre- and post-rainfall VPD differences and the duration of rainless interval. R. pseudoacacia showed a larger immediate post-rainfall Ec increase than P. tabulaeformis did. We, therefore, concluded that concentrated rainfall events do not trigger significant increase of transpiration unless large events penetrate the deep soil and the species differences of Ec in response to pulses of rain may shape the composition of semiarid woodlands under future rainfall regimes. PMID:24510059

  16. The response of Pinus sylvestris to drought: stomatal control of transpiration and hydraulic conductance.

    PubMed

    Irvine, J.; Perks, M. P.; Magnani, F.; Grace, J.

    1998-06-01

    We investigated the impact of drought on the physiology of 41-year-old Scots pine (Pinus sylvestris L.) in central Scotland. Measurements were made of the seasonal course of transpiration, canopy stomatal conductance, needle water potential, xylem water content, soil-to-needle hydraulic resistance, and growth. Comparison was made between drought-treated plots and those receiving average precipitation. In response to drought, transpiration rate declined once volumetric water content (VWC) over the top 20 cm of soil reached a threshold value of 12%. Thereafter, transpiration was a near linear function of soil water content. As the soil water deficit developed, the hydraulic resistance between soil and needles increased by a factor of three as predawn needle water potential declined from -0.54 to -0.71 MPa. A small but significant increase in xylem embolism was detected in 1-year-old shoots. Stomatal control of transpiration prevented needle water potential from declining below -1.5 MPa. Basal area, and shoot and needle growth were significantly reduced in the drought treatment. In the year following the drought, canopy stomatal conductance and soil-to-needle hydraulic resistance recovered. Current-year needle extension recovered, but a significant reduction in basal area increment was evident one year after the drought. The results suggest that, in response to soil water deficit, mature Scots pine closes its stomata sufficiently to prevent the development of substantial xylem embolism. Reduced growth in the year after a severe soil water deficit is most likely to be the result of reduced assimilation in the year of the drought, rather than to any residual embolism carried over from one year to the next. PMID:12651364

  17. Response of transpiration to rain pulses for two tree species in a semiarid plantation

    NASA Astrophysics Data System (ADS)

    Chen, Lixin; Zhang, Zhiqiang; Zeppel, Melanie; Liu, Caifeng; Guo, Junting; Zhu, Jinzhao; Zhang, Xuepei; Zhang, Jianjun; Zha, Tonggang

    2014-09-01

    Responses of transpiration ( E c) to rain pulses are presented for two semiarid tree species in a stand of Pinus tabulaeformis and Robinia pseudoacacia. Our objectives are to investigate (1) the environmental control over the stand transpiration after rainfall by analyzing the effect of vapor pressure deficit (VPD), soil water condition, and rainfall on the post-rainfall E c development and recovery rate, and (2) the species responses to rain pulses and implications on vegetation coverage under a changing rainfall regime. Results showed that the sensitivity of canopy conductance ( G c) to VPD varied under different incident radiation and soil water conditions, and the two species exhibited the same hydraulic control (-d G c/dlnVPD to G cref ratio) over transpiration. Strengthened physiological control and low sapwood area of the stand contributed to low E c. VPD after rainfall significantly influenced the magnitude and time series of post-rainfall stand E c. The fluctuation of post-rainfall VPD in comparison with the pre-rainfall influenced the E c recovery. Further, the stand E c was significantly related to monthly rainfall, but the recovery was independent of the rainfall event size. E c enhanced with cumulative soil moisture change (?VWC) within each dry-wet cycle, yet still was limited in large rainfall months. The two species had different response patterns of post-rainfall E c recovery. E c recovery of P. tabulaeformis was influenced by the pre- and post-rainfall VPD differences and the duration of rainless interval. R. pseudoacacia showed a larger immediate post-rainfall E c increase than P. tabulaeformis did. We, therefore, concluded that concentrated rainfall events do not trigger significant increase of transpiration unless large events penetrate the deep soil and the species differences of E c in response to pulses of rain may shape the composition of semiarid woodlands under future rainfall regimes.

  18. Thermal transpiration through single walled carbon nanotubes and graphene channels

    SciTech Connect

    Thekkethala, Joe Francis; Sathian, Sarith P., E-mail: sarith@nitc.ac.in [Computational Nanotechnology Laboratory, School of Nano Science and Technology, National Institute of Technology Calicut, Kozhikode, Kerala - 673601 (India)

    2013-11-07

    Thermal transpiration through carbon nanotubes (CNTs) and graphene channels is studied using molecular dynamics (MD) simulations. The system consists of two reservoirs connected by a CNT. It is observed that a flow is developed inside the CNT from the low temperature reservoir to the high temperature reservoir when the two reservoirs are maintained at different temperatures. The influence of channel size and temperature gradient on the mean velocity is analysed by varying the CNT diameter and the temperature of one of the reservoirs. Larger flow rate is observed in the smaller diameter CNTs showing an increase in the mean velocity with increase in the temperature gradient. For the flow developed inside the CNTs, slip boundaries occur and the slip length is calculated using the velocity profile. We examine the effect of fluid-wall interaction strength (?{sub fw}), diffusivity (D), and viscosity of the fluid (?) on the temperature induced fluid transport through the CNTs. Similar investigations are also carried out by replacing the CNT with a graphene channel. Results show that the mean velocity of the fluid atoms in the graphene channel is lower than that through the CNTs. This can be attributed to the higher degree of confinement observed in the CNTs.

  19. Plant N capture from pulses: effects of pulse size, growth rate, and other soil resources

    Microsoft Academic Search

    J. J. James; J. H. Richards

    2005-01-01

    In arid ecosystems, the ability to rapidly capture nitrogen (N) from brief pulses is expected to influence plant growth, survival,\\u000a and competitive ability. Theory and data suggest that N capture from pulses should depend on plant growth rate and availability\\u000a of other limiting resources. Theory also predicts trade-offs in plant stress tolerance and ability to capture N from different\\u000a size

  20. Small Variance in Growth Rate in Annual Plants has Large Effects on Genetic Drift

    Technology Transfer Automated Retrieval System (TEKTRAN)

    When plant size is strongly correlated with plant reproduction, variance in growth rates results in a lognormal distribution of seed production within a population. Fecundity variance affects effective population size (Ne), which reflects the ability of a population to maintain beneficial mutations ...

  1. Cancer rates after the Three Mile Island nuclear accident and proximity of residence to the plant

    Microsoft Academic Search

    M. C. Hatch; S. Wallenstein; J. Beyea; J. W. Nieves; M. Susser

    1991-01-01

    In the light of a possible link between stress and cancer promotion or progression, and of previously reported distress in residents near the Three Mile Island (TMI) nuclear power plant, we attempted to evaluate the impact of the March 1979 accident on community cancer rates. Proximity of residence to the plant, which related to distress in previous studies, was taken

  2. Oxidation mechanism and overall removal rates of endocrine disrupting chemicals by aquatic plants.

    PubMed

    Reis, A R; Tabei, K; Sakakibara, Y

    2014-01-30

    The purpose of this study was to evaluate experimentally and theoretically the oxidation mechanisms and overall removal rates of phenolic endocrine disrupting chemicals (EDCs) by aquatic plants. EDCs used in this study were bisphenol-A (BPA), 2,4-dichlorophenol (2,4-DCP), 4-tert-octylphenol (4-t-OP), and pentachlorophenol (PCP). Referring to reported detection levels in aquatic environments and contaminated sites, the feed concentration of each EDC was set from 1 to 100?g/L. Experimental results showed that, except for PCP, phenolic EDCs were stably and concurrently removed by different types of aquatic plants over 70 days in long-term continuous treatments. Primal enzymes responsible for oxidation of BPA, 2,4-DCP, and 4-t-OP were peroxidases (POs). Moreover, enzymatic removal rates of BPA, 2,4-DCP, and 4-t-OP by POs were more than 2 orders of magnitude larger than those by aquatic plants. Assuming that overall removal rates of EDCs are controlled by mass transfer rates onto liquid films on the surface of aquatic plants, an electrochemical method based on the limiting current theory was developed to measure the mass transfer rates of EDCs. Because of extremely large removal rates of EDCs by POs, observed removal rates by aquatic plants were in reasonably good agreement with calculated results by a mathematical model developed based on an assumption that mass transfer limitation is a rate-limiting step. PMID:24333944

  3. Impact of plant shoot architecture on leaf cooling: a coupled heat and mass transfer model

    PubMed Central

    Bridge, L. J.; Franklin, K. A.; Homer, M. E.

    2013-01-01

    Plants display a range of striking architectural adaptations when grown at elevated temperatures. In the model plant Arabidopsis thaliana, these include elongation of petioles, and increased petiole and leaf angles from the soil surface. The potential physiological significance of these architectural changes remains speculative. We address this issue computationally by formulating a mathematical model and performing numerical simulations, testing the hypothesis that elongated and elevated plant configurations may reflect a leaf-cooling strategy. This sets in place a new basic model of plant water use and interaction with the surrounding air, which couples heat and mass transfer within a plant to water vapour diffusion in the air, using a transpiration term that depends on saturation, temperature and vapour concentration. A two-dimensional, multi-petiole shoot geometry is considered, with added leaf-blade shape detail. Our simulations show that increased petiole length and angle generally result in enhanced transpiration rates and reduced leaf temperatures in well-watered conditions. Furthermore, our computations also reveal plant configurations for which elongation may result in decreased transpiration rate owing to decreased leaf liquid saturation. We offer further qualitative and quantitative insights into the role of architectural parameters as key determinants of leaf-cooling capacity. PMID:23720538

  4. Impact of plant shoot architecture on leaf cooling: a coupled heat and mass transfer model.

    PubMed

    Bridge, L J; Franklin, K A; Homer, M E

    2013-08-01

    Plants display a range of striking architectural adaptations when grown at elevated temperatures. In the model plant Arabidopsis thaliana, these include elongation of petioles, and increased petiole and leaf angles from the soil surface. The potential physiological significance of these architectural changes remains speculative. We address this issue computationally by formulating a mathematical model and performing numerical simulations, testing the hypothesis that elongated and elevated plant configurations may reflect a leaf-cooling strategy. This sets in place a new basic model of plant water use and interaction with the surrounding air, which couples heat and mass transfer within a plant to water vapour diffusion in the air, using a transpiration term that depends on saturation, temperature and vapour concentration. A two-dimensional, multi-petiole shoot geometry is considered, with added leaf-blade shape detail. Our simulations show that increased petiole length and angle generally result in enhanced transpiration rates and reduced leaf temperatures in well-watered conditions. Furthermore, our computations also reveal plant configurations for which elongation may result in decreased transpiration rate owing to decreased leaf liquid saturation. We offer further qualitative and quantitative insights into the role of architectural parameters as key determinants of leaf-cooling capacity. PMID:23720538

  5. Dioecy is associated with higher diversification rates in flowering plants.

    PubMed

    Käfer, J; de Boer, H J; Mousset, S; Kool, A; Dufay, M; Marais, G A B

    2014-07-01

    In angiosperms, dioecious clades tend to have fewer species than their nondioecious sister clades. This departure from the expected equal species richness in the standard sister clade test has been interpreted as implying that dioecious clades diversify less and has initiated a series of studies suggesting that dioecy might be an 'evolutionary dead end'. However, two of us recently showed that the 'equal species richness' null hypothesis is not valid in the case of derived char acters, such as dioecy, and proposed a new test for sister clade comparisons; preliminary results, using a data set available in the litterature, indicated that dioecious clades migth diversify more than expected. However, it is crucial for this new test to distinguish between ancestral and derived cases of dioecy, a criterion that was not taken into account in the available data set. Here, we present a new data set that was obtained by searching the phylogenetic literature on more than 600 completely dioecious angiosperm genera and identifying 115 sister clade pairs for which dioecy is likely to be derived (including > 50% of the dioecious species). Applying the new sister clade test to this new dataset, we confirm the preliminary result that dioecy is associated with an increased diversification rate, a result that does not support the idea that dioecy is an evolutionary dead end in angiosperms. The traits usually associated with dioecy, that is, an arborescent growth form, abiotic pollination, fleshy fruits or a tropical distribution, do not influence the diversification rate. Rather than a low diversification rate, the observed species richness patterns of dioecious clades seem to be better explained by a low transition rate to dioecy and frequent losses. PMID:24797166

  6. The Effect of Planting Strategies, Imazethapyr Rates, and Application Timings on CLEARFIELD® Hybrid Rice Injury

    E-print Network

    Turner, Aaron Lyles

    2012-02-14

    THE EFFECT OF PLANTING STRATEGIES, IMAZETHAPYR RATES, AND APPLICATION TIMINGS ON CLEARFIELD? HYBRID RICE INJURY A Thesis by AARON LYLES TURNER Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment... of the requirements for the degree of MASTER OF SCIENCE December 2011 Major Subject: Agronomy THE EFFECT OF PLANTING STRATEGIES, IMAZETHAPYR RATES, AND APPLICATION TIMINGS ON CLEARFIELD? HYBRID RICE INJURY A Thesis by AARON LYLES TURNER Submitted to the Office...

  7. Gas Exchange, Transpiration and Yield of Sweetpotato Grown in a Controlled Environment

    NASA Technical Reports Server (NTRS)

    Barta, Daniel J.; Henderson, Keith E.; Mortley, Desmond G.; Henninger, Donald L.

    2000-01-01

    Sweetpotato was grown to harvest maturity within NASA Johnson Space Center's Variable Pressure Growth Chamber (VPGC) to characterize crop performance for potential use in advanced life support systems as a contributor to food production, air revitalization and resource recovery. Stem cuttings of breeding clone "TU-82-155" were grown hydroponically at a density of 17 plants m(sup -2) using a modified pressure-plate growing system (Patent No. 4860-490, Tuskegee University). Lighting was provided by HPS lamps at a photoperiod of 12h light: 12h dark. The photosynthetic photon flux was maintained at 500, 750 and 1000 micro mol m(sup -2) s(sub -1) during days 1-15, 16-28, 29-119, respectively. Canopy temperatures were maintained at 28 C: light: 22 C:dark. During the light period, relative humidity and carbon dioxide were maintained at 70% and 1200 micro liters l(sup -1), respectively. Nutrient solution was manually adjusted 2 to 4 times per week by addition of 10X concentrated modified half-strength Hoagland nutrient salts and NaOH to return the electrical conductivity and pH to 1.2 mS cm(sup -1) and 6.0, respectively. At 17 weeks (119 days) from transplanting, a total of 56.5 kilograms fresh mass of storage roots (84.1% moisture) were harvested from the 11.2 m(sup 2) chamber, resulting in a yield 5.0 kilograms m(sup -2). Harvest index, based on fresh mass, was 38.6%. Rates of net photosynthesis, dark respiration, transpiration, and ethylene production will be reported.

  8. Ethylene synthesis and sensitivity in crop plants

    NASA Technical Reports Server (NTRS)

    Klassen, Stephen P.; Bugbee, Bruce

    2004-01-01

    Closed and semi-closed plant growth chambers have long been used in studies of plant and crop physiology. These studies include the measurement of photosynthesis and transpiration via photosynthetic gas exchange. Unfortunately, other gaseous products of plant metabolism can accumulate in these chambers and cause artifacts in the measurements. The most important of these gaseous byproducts is the plant hormone ethylene (C2H4). In spite of hundreds of manuscripts on ethylene, we still have a limited understanding of the synthesis rates throughout the plant life cycle. We also have a poor understanding of the sensitivity of intact, rapidly growing plants to ethylene. We know ethylene synthesis and sensitivity are influenced by both biotic and abiotic stresses, but such whole plant responses have not been accurately quantified. Here we present an overview of basic studies on ethylene synthesis and sensitivity.

  9. PVUSA procurement, acceptance, and rating practices for photovoltaic power plants

    SciTech Connect

    Dows, R.N.; Gough, E.J.

    1995-09-01

    This report is one in a series of PVUSA reports on PVUSA experiences and lessons learned at the demonstration sites in Davis and Kerman, California, and from participating utility host sites. During the course of approximately 7 years (1988--1994), 10 PV systems have been installed ranging from 20 kW to 500 kW. Six 20-kW emerging module technology arrays, five on universal project-provided structures and one turnkey concentrator, and four turnkey utility-scale systems (200 to 500 kW) were installed. PVUSA took a very proactive approach in the procurement of these systems. In the absence of established procurement documents, the project team developed a comprehensive set of technical and commercial documents. These have been updated with each successive procurement. Working closely with vendors after the award in a two-way exchange provided designs better suited for utility applications. This report discusses the PVUSA procurement process through testing and acceptance, and rating of PV turnkey systems. Special emphasis is placed on the acceptance testing and rating methodology which completes the procurement process by verifying that PV systems meet contract requirements. Lessons learned and recommendations are provided based on PVUSA experience.

  10. Improvement of growth rate of plants by bubble discharge in water

    NASA Astrophysics Data System (ADS)

    Takahata, Junichiro; Takaki, Koichi; Satta, Naoya; Takahashi, Katsuyuki; Fujio, Takuya; Sasaki, Yuji

    2015-01-01

    The effect of bubble discharge in water on the growth rate of plants was investigated experimentally for application to plant cultivation systems. Spinach (Spinacia oleracea), radish (Raphanus sativus var. sativus), and strawberry (Fragaria × ananassa) were used as specimens to clarify the effect of the discharge treatment on edible parts of the plants. The specimens were cultivated in pots filled with artificial soil, which included chicken manure charcoal. Distilled water was sprayed on the artificial soil and drained through a hole in the pots to a water storage tank. The water was circulated from the water storage tank to the cultivation pots after 15 or 30 min discharge treatment on alternate days. A magnetic compression-type pulsed power generator was used to produce the bubble discharge with a repetition rate of 250 pps. The plant height in the growth phase and the dry weight of the harvested plants were improved markedly by the discharge treatment in water. The soil and plant analyzer development (SPAD) value of the plants also improved in the growth phase of the plants. The concentration of nitrate nitrogen, which mainly contributed to the improvement of the growth rate, in the water increased with the discharge treatment. The Brix value of edible parts of Fragaria × ananassa increased with the discharge treatment. The inactivation of bacteria in the water was also confirmed with the discharge treatment.

  11. Plant traits are the predominant control on litter decomposition rates within biomes worldwide

    Microsoft Academic Search

    William K. Cornwell; Johannes H. C. Cornelissen; K. Amatangalo; Ellen Dorrepaal; Valerie T. Eviner; Oscar Godoy; S. E. Hobbir; Bart Hoorens; Hiroko Kurokawa; N. Perez-Harguindeguy; Helen M. Quested; Louis S. Santiago; David A. Wardle; Ian J. Wright; Rien Aerts; Steven D. Allison; Bodegom van P. M; Victor Brovkin; Alex Chatain; Terry V. Callaghan; S. Diaz; Eric Garnier; Diego E. Gurvich; Elena Kazakou; Julia A. Klein; Jenny Read; Peter B. Reich; Nadejda A. Soudzilovskaia; M. Victoria Vaieretti; Mark Westoby

    2008-01-01

    Worldwide decomposition rates depend both on climate and the legacy of plant functional traits as litter quality. To quantify the degree to which functional differentiation among species affects their litter decomposition rates, we brought together leaf trait and litter mass loss data for 818 species from 66 decomposition experiments on six continents. We show that: (i) the magnitude of species-driven

  12. Response of Insect Relative Growth Rate to Temperature and Host-Plant Phenology: Estimation and Validation

    E-print Network

    Paris-Sud XI, Université de

    Response of Insect Relative Growth Rate to Temperature and Host-Plant Phenology: Estimation, Parisey N, Fournier G, Taupin P, Dedryver C-A, et al. (2014) Response of Insect Relative Growth Rate fluctuations on living organisms. Changes in populations of indigenous or invasive insect pests are one

  13. A study on the optimal hydraulic loading rate and plant ratios in recirculation aquaponic system

    Microsoft Academic Search

    Azizah Endut; A. Jusoh; N. Ali; W. B. Wan Nik; A. Hassan

    2010-01-01

    The growths of the African catfish (Clarias gariepinus) and water spinach (Ipomoea aquatica) were evaluated in recirculation aquaponic system (RAS). Fish production performance, plant growth and nutrient removal were measured and their dependence on hydraulic loading rate (HLR) was assessed. Fish production did not differ significantly between hydraulic loading rates. In contrast to the fish production, the water spinach yield

  14. Growth rates of rhizosphere microorganisms depend on competitive abilities of plants for nitrogen

    NASA Astrophysics Data System (ADS)

    Blagodatskaya, Evgenia; Littschwager, Johanna; Lauerer, Marianna; Kuzyakov, Yakov

    2010-05-01

    Rhizosphere - one of the most important ‘hot spots' in soil - is characterized not only by accelerated turnover of microbial biomass and nutrients but also by strong intra- and inter-specific competition. Intra-specific competition occurs between individual plants of the same species, while inter-specific competition can occur both at population level (plant species-specific, microbial species-specific interactions) and at community level (plant - microbial interactions). Such plant - microbial interactions are mainly governed by competition for available N sources, since N is one of the main growth limiting nutrients in natural ecosystems. Functional structure and activity of microbial community in rhizosphere is not uniform and is dependent on quantity and quality of root exudates which are plant specific. It is still unclear how microbial growth and turnover in the rhizosphere are dependent on the features and competitive abilities of plants for N. Depending on C and N availability, acceleration and even retardation of microbial activity and carbon mineralization can be expected in the rhizosphere of plants with high competitive abilities for N. We hypothesized slower microbial growth rates in the rhizosphere of plants with smaller roots, as they usually produce less exudates compared to plants with small shoot-to-root ratio. As the first hypothesis is based solely on C availability, we also expected the greater effect of N availability on microbial growth in rhizosphere of plants with smaller root mass. These hypothesis were tested for two plant species of strawberry: Fragaria vesca L. (native species), and Duchesnea indica (Andrews) Focke (an invasive plant in central Europe) growing in intraspecific and interspecific competition. Microbial biomass and the kinetic parameters of microbial growth in the rhizosphere were estimated by dynamics of CO2 emission from the soil amended with glucose and nutrients. Specific growth rate (µ) of soil microorganisms was estimated by fitting the parameters of the equation: CO2(t) = A + B × exp(µ×t), to the measured CO2 production rate (CO2(t)) after glucose addition, where A is the initial respiration rate uncoupled from ATP production, B the initial rate of the growing fraction of total respiration coupled with ATP generation and cell growth, and t time. Our study revealed the linkage between growth strategies of rhizosphere microorganisms and different adaptation strategies of F. vesca and D. indica to N limitation. Plant - strong competitor for N (D. indica) did not change root mass under N limitation causing the deficit of N in the rhizosphere and altering the structure of rhizosphere microbial community. Benefiting of slow growing microorganisms with K-strategy under N limiting conditions was indicated by strong decrease in specific microbial growth rates in the rhizosphere of D. indica. Root mass of the plant with weak competitive abilities for N (F. vesca) increased under lack of N to compensate the lack of nutrients. The increase in root mass and possible increase in amount of root exudates coincided with no structural changes in microbial community in rhizosphere of F. vesca. By intraspecific competition at low N level a 2.4-fold slower microbial specific growth rates were observed under D. indica (0.09 h-1) characterized by smaller root biomass and lower N content in roots compared with F. vesca. The generation time of actively growing microbial biomass was for the 6 hours longer in rhizosphere of D. indica than under F. vesca (10.7 to 4.6 h, respectively). Thus, under N limitation the strong competition for N between plant and microorganisms decreased microbial growth rates and carbon turnover in rhizosphere. By interspecific competition of both plants at low N level, microbial growth rates were similar to those for D. indica indicating that plant with stronger competitive abilities for N controls microbial community in the rhizosphere. At high N availability the root biomass did not differ significantly between both plants. This resulted in similar microbial growt

  15. Lower selfing rate at higher altitudes in the alpine plant Eritrichium nanum (Boraginaceae).

    PubMed

    Wirth, Lea Rahel; Graf, René; Gugerli, Felix; Landergott, Urs; Holderegger, Rolf

    2010-05-01

    A general hypothesis on mating patterns in alpine plants states that self-fertilization should increase with increasing altitude as a result of pollinator limitation at higher altitudes. However, realized selfing rates under natural conditions, as based on genetic progeny analysis, have not yet been determined for any alpine species across altitude. We therefore assessed the realized selfing rates in about 100 open-pollinated families of the high-alpine cushion plant Eritrichium nanum, sampled along an altitudinal gradient in the Swiss Alps, by using progeny analysis based on six microsatellites. In marked contrast to the general hypothesis, realized selfing rates in E. nanum significantly decreased with increasing altitude, and only progenies from low altitudes were predominantly selfed. However, the higher selfing rates of individuals at lower altitudes could have been caused by unfavorable weather conditions during early growing season when low-elevation plants flowered. In summary, our results on selfing rates in an alpine plant across altitude as well as the results of other studies using experimental hand-pollinations and/or population genetic methods generally do not support the expectation of higher selfing rates at higher altitudes. We therefore ask for further critical examination of realized mating systems in alpine plants. PMID:21622454

  16. Parasitic plants have increased rates of molecular evolution across all three genomes

    PubMed Central

    2013-01-01

    Background Theoretical models and experimental evidence suggest that rates of molecular evolution could be raised in parasitic organisms compared to non-parasitic taxa. Parasitic plants provide an ideal test for these predictions, as there are at least a dozen independent origins of the parasitic lifestyle in angiosperms. Studies of a number of parasitic plant lineages have suggested faster rates of molecular evolution, but the results of some studies have been mixed. Comparative analysis of all parasitic plant lineages, including sequences from all three genomes, is needed to examine the generality of the relationship between rates of molecular evolution and parasitism in plants. Results We analysed DNA sequence data from the mitochondrial, nuclear and chloroplast genomes for 12 independent evolutionary origins of parasitism in angiosperms. We demonstrated that parasitic lineages have a faster rate of molecular evolution than their non-parasitic relatives in sequences for all three genomes, for both synonymous and nonsynonymous substitutions. Conclusions Our results prove that raised rates of molecular evolution are a general feature of parasitic plants, not confined to a few taxa or specific genes. We discuss possible causes for this relationship, including increased positive selection associated with host-parasite arms races, relaxed selection, reduced population size or repeated bottlenecks, increased mutation rates, and indirect causal links with generation time and body size. We find no evidence that faster rates are due to smaller effective populations sizes or changes in selection pressure. Instead, our results suggest that parasitic plants have a higher mutation rate than their close non-parasitic relatives. This may be due to a direct connection, where some aspect of the parasitic lifestyle drives the evolution of raised mutation rates. Alternatively, this pattern may be driven by an indirect connection between rates and parasitism: for example, parasitic plants tend to be smaller than their non-parasitic relatives, which may result in more cell generations per year, thus a higher rate of mutations arising from DNA copy errors per unit time. Demonstration that adoption of a parasitic lifestyle influences the rate of genomic evolution is relevant to attempts to infer molecular phylogenies of parasitic plants and to estimate their evolutionary divergence times using sequence data. PMID:23782527

  17. Sap flux-upscaled canopy transpiration, stomatal conductance, and water use efficiency in an old growth forest in the Great Lakes region of the United States

    NASA Astrophysics Data System (ADS)

    Tang, Jianwu; Bolstad, Paul V.; Ewers, Brent E.; Desai, Ankur R.; Davis, Kenneth J.; Carey, Eileen V.

    2006-06-01

    Combining sap flux and eddy covariance measurements provides a means to study plant stomatal conductance and the relationship between transpiration and photosynthesis. We measured sap flux using Granier-type sensors in a northern hardwood-dominated old growth forest in Michigan, upscaled to canopy transpiration, and calculated canopy conductance. We also measured carbon and water fluxes with the eddy covariance method and derived daytime gross primary production (GPP). The diurnal patterns of sap flux and canopy transpiration were mainly controlled by vapor pressure deficit (D) and photosynthetically active radiation (PAR). Daily sums of sap flux and canopy transpiration had exponential relationships to D that saturated at higher D and had linear relationships to PAR. Sugar maple (Acer saccharum) and yellow birch (Betula alleghaniesis) had higher sap flux per unit of sapwood area than eastern hemlock (Tsuga canadensis), while sugar maple and hemlock had higher canopy transpiration per unit of leaf area than yellow birch. Sugar maple dominated canopy transpiration per ground area. Canopy transpiration averaged 1.57 mm d-1, accounting for 65% of total evapotranspiration in the growing season. Canopy conductance was controlled by both D and PAR, but the day-to-day variation in canopy conductance mainly followed a negatively logarithmic relationship with D. By removing the influences of PAR, half-hourly canopy conductance was also negatively logarithmically correlated with D. Water use efficiency (WUE) had a strong exponential relationship with D on a daily basis and approached a minimum of 4.4 mg g-1. WUE provides an alternative to estimate GPP from measurements of sap flux.

  18. Effects of elevated atmospheric CO{sub 2} on canopy transpiration in senescent spring wheat

    SciTech Connect

    Grossman, S.; Kimball, B.A.; Hunsaker, D.J.; Long, S.P. et al

    1998-12-31

    The seasonal course of canopy transpiration and the diurnal courses of latent heat flux of a spring wheat crop were simulated for atmospheric CO{sub 2} concentrations of 370 {micro}mol mol{sup {minus}1} and 550 {micro}mol mol{sup {minus}1}. The hourly weather data, soil parameters and the irrigation and fertilizer treatments of the Free-Air Carbon Dioxide Enrichment wheat experiment in Arizona (1992/93) were used to drive the model. The simulation results were tested against field measurements with special emphasis on the period between anthesis and maturity. A model integrating leaf photosynthesis and stomatal conductance was scaled to a canopy level in order to be used in the wheat growth model. The simulated intercellular CO{sub 2} concentration, C{sub i} was determined from the ratio of C{sub i} to the CO{sub 2} concentration at the leaf surface, C{sub s}, the leaf to air specific humidity deficit and a possibly unfulfilled transpiration demand. After anthesis, the measured assimilation rates of the flag leaves decreased more rapidly than their stomatal conductances, leading to a rise in the C{sub i}/C{sub s} ratio. In order to describe this observation, an empirical model approach was developed which took into account the leaf nitrogen content for the calculation of the C{sub i}/C{sub s} ratio. Simulation results obtained with the new model version were in good agreement with the measurements. If changes in the C{sub i}/C{sub s} ratio accorded to the decrease in leaf nitrogen content during leaf senescence were not considered in the model, simulations revealed an underestimation of the daily canopy transpiration of up to twenty percent and a decrease in simulated seasonal canopy transpiration by ten percent. The measured reduction in the seasonal sum of canopy transpiration and soil evaporation owing to CO{sub 2} enrichment, in comparison, was only about five percent.

  19. Study of deposition control using transpiration. Technical progress report

    SciTech Connect

    Louis, J.F.; Kozlu, H.

    1984-12-01

    The purpose of this project is to determine the conditions in which transpiration may be used to avoid deposition of small particles. The application of this work is the control of the deposition of small particles over a surface kept at a temperature below the melting point of compounds likely to exist in the combustion products. A combined experimental and theoretical research program will be carried out to evaluate the concept of transpiration as a deposition control strategy. A first order theory will be refined by introducing an appropriate turbulence model. The experimental program is designed to evaluate and refine the theoretical model under conditions which provide the correct Reynolds and Stokes numbers. The experimental set up consists of a wind tunnel containing a flat porous transpired section. The measurements will determine the distribution of velocity and of particles concentration in the boundary layer. The experiments will be conducted with different particle sizes under conditions simulating gas turbine conditions.

  20. Transpiration's inhibition of air pollution fluxes to substomatal cavities. [PRECP

    SciTech Connect

    Slinn, W.G.N.

    1987-05-01

    This report presents an estimate for the resistance to transport through stomatal openings, accounting for the counterflowing flux of water vapor associated with transpiration. The specific goal of this report is to estimate the influence of transpiration on the stomatal resistance, r/sub sto/; others have estimated the substomatal and mesophyll resistances r/sub ssc/ and r/sub mes/. It might be expected that any influence of the water-vapor flux on pollutant transport would be a maximum at the stomatal opening since, at the constricted area of the stoma, the water flux is a maximum. Transpiration through stomata appears to insigifnicantly inhibit the passage of relatively small molecules (e.g., SO/sub 2/, O/sub 3/, HNO/sub 3/, PAN, etc.) through the stomata, and therefore, by entering the substomatal cavity, such pollutants have greater potential for threatening plan survival, if their concentrations are excessive. 7 refs., 5 figs.

  1. Effect, uptake and disposition of nitrobenzene in several terrestrial plants

    SciTech Connect

    McFarlane, C.; Pfleeger, T.; Fletcher, J.

    1990-01-01

    Eight species of plants were exposed to nitrobenzene in a hydroponic solution. Four species experienced no depression of either transpiration or photosynthetic rates, while one was rapidly killed and the other three were temporarily affected but recovered from the treatment. Uptake of nitrobenzene was passive and was shown to be proportional to the rate of water flux in each species. The transpiration stream concentration factor (TSCF) was 0.72. The root concentration factor (RCF) was variable between the species and was higher than expected, presumably due to deposits of insoluble metabolic products. All of the species examined displayed a capacity to chemically alter nonpolar nitrobenzene into both polar and insoluble products. Volatilization of nitrobenzene from the leaves was a major route of chemical loss.

  2. A study on the optimal hydraulic loading rate and plant ratios in recirculation aquaponic system.

    PubMed

    Endut, Azizah; Jusoh, A; Ali, N; Wan Nik, W B; Hassan, A

    2010-03-01

    The growths of the African catfish (Clarias gariepinus) and water spinach (Ipomoea aquatica) were evaluated in recirculation aquaponic system (RAS). Fish production performance, plant growth and nutrient removal were measured and their dependence on hydraulic loading rate (HLR) was assessed. Fish production did not differ significantly between hydraulic loading rates. In contrast to the fish production, the water spinach yield was significantly higher in the lower hydraulic loading rate. Fish production, plant growth and percentage nutrient removal were highest at hydraulic loading rate of 1.28 m/day. The ratio of fish to plant production has been calculated to balance nutrient generation from fish with nutrient removal by plants and the optimum ratio was 15-42 gram of fish feed/m(2) of plant growing area. Each unit in RAS was evaluated in terms of oxygen demand. Using specified feeding regime, mass balance equations were applied to quantify the waste discharges from rearing tanks and treatment units. The waste discharged was found to be strongly dependent on hydraulic loading rate. PMID:19819130

  3. Chilling rate effects on pork loin tenderness in commercial processing plants.

    PubMed

    Shackelford, S D; King, D A; Wheeler, T L

    2012-08-01

    The present experiment was conducted to provide a large-scale objective comparison of pork LM tenderness and other meat quality traits among packing plants that differ in stunning method and carcass chilling rate. For each of 2 replicates, pigs were sourced from a single barn of a commercial finishing operation that fed pigs from a single terminal crossbred line. On each day, 3 trucks were loaded, with each of those trucks delivering the pigs to a different plant. Plant A used CO(2) stunning and conventional spray chilling; Plant B used CO(2) stunning and blast chilling; and Plant C used electrical stunning and blast chilling. The boneless, vacuum-packaged loin was obtained from the left side of each carcass (n = 597; 100 · plant(-1) · replicate(-1)). As designed, HCW, LM depth, and LM intramuscular fat percentage did not differ among plants (P > 0.05). By 1.67 h postmortem (1 h after the carcasses exited the harvest floor), the average deep LM temperature was >10°C warmer for Plant A than Plants B and C (32.1°C, 21.6°C, and 19.3°C, for Plants A, B, and C, respectively) and deep LM temperature continued to be >10°C warmer for Plant A until 4.17 h or 6.33 h postmortem than for Plants C and B, respectively. Both plants that used blast chilling produced loins with greater LM slice shear force at 15 d postmortem than did the plant that used conventional spray chilling (P < 0.0001). The frequency of loins with excessively high (>25 kg) LM slice shear force values was greater for Plant B than Plant A (14.7% vs. 1%; P < 0.01). Among all the traits studied, including visual and instrumental evaluations of LM color, ultimate pH, marbling score, and lean color stability, the only other difference between Plants A and B was that purge loss during 13 d (from d 1 to 14) of vacuum-packaged storage was greater for Plant B (P < 0.05). That is, with this sample of pigs and CO(2) stunning, no loin quality advantages were detected for blast chilling. Regardless of chilling method, CO(2) stunning resulted in darker LM lean color and greater LM water-holding capacity than did electrical stunning (P < 0.05). This research shows that differences in chilling systems among pork packing plants can have a strong influence on loin chop tenderness. PMID:22307481

  4. Gas crossflow effects on airflow through a wire-form transpiration cooling material

    NASA Technical Reports Server (NTRS)

    Kaufman, A. S.; Russell, L. M.; Poferl, D. J.

    1972-01-01

    An experimental analysis was conducted to determine the effects of gas stream flow parallel to the discharging surface on the flow characteristics of a wire-form porous material. Flow data were obtained over a range of transpiration airflow rates from 0.129 to 0.695/grams per second-centimeter squared and external gas stream Mach numbers from 0 to 0.46. The conclusion was drawn that the flow characteristics of the wire cloth were not significantly affected by the external gas flows.

  5. Measurement of Effective Canopy Temperature: The Missing Link to Modeling Transpiration in Controlled Environments

    NASA Technical Reports Server (NTRS)

    Monje, O. A.; McCormack, Ann; Bugbee, Bruce; Jones, Harry W., Jr. (Technical Monitor)

    1994-01-01

    The objectives were to apply energy balance principles to plant canopies, and to determine which parameters are essential for predicting plant canopy transpiration (E) in controlled environments. Transpiration was accurately measured in a gas-exchange system. Absorbed radiation (R(sub abs)) by the canopy was measured with a net radiometer and calculated from short and long-wave radiation components. Average canopy foliar temperature T(sub L) can be measured with an infrared radiometer, but since T(sub L) is seldom uniform, a weighed average measurement of T(sub L) must be made. The effective canopy temperature T(sub C) is that temperature that balances the energy flux between absorbed radiation and latent heat L(sub E) and sensible heat (H) fluxes. TC should exactly equal air temperature T(sub A) when L(sub E) equals R(sub abs). When unnecessary thermal radiation from the lighting system is removed by a water filter, the magnitude of L(sub E) from transpiration approaches Rabs and T(sub C) is close to T(sub A). Unlike field models, we included the energy used in photosynthesis and found that up to 10% of Rabs was used in photosynthesis. We calculated aerodynamic conductance for H from measurements of wind speed and canopy height using the wind profile equation. Canopy aerodynamic conductance ranged from.03 to.04 m/s for wind speeds from.6 to 1 m/s; thus a 0.1 C canopy to air temperature difference results in a sensible heat flux of about 4 W/sq m, which is only 1% of R(sub abs). We examined the ability of wide angle infrared transducers to accurately integrate T(sub L) from the top to the bottom of the canopy. We measured evaporation from the hydroponic media to be approximately 1 micro mol/sq m s or 10% of R(sub abs). This result indicates that separating evaporation from transpiration is more important than exact measurement of canopy temperature.

  6. Hydrogen isotope ratios of leaf wax n-alkanes in grasses are insensitive to transpiration

    NASA Astrophysics Data System (ADS)

    McInerney, Francesca A.; Helliker, Brent R.; Freeman, Katherine H.

    2011-01-01

    We analyzed hydrogen isotope ratios of high-molecular weight n-alkanes ( ?D l) and oxygen isotope ratios of ?-cellulose ( ?18O C) for C 3 and C 4 grasses grown in the field and in controlled-environment growth chambers. The relatively firm understanding of 18O-enrichment in leaf water and ?-cellulose was used to elucidate fractionation patterns of ?D l signatures. In the different relative humidity environments of the growth chambers, we observed clear and predictable effects of leaf-water enrichment on ?18O C values. Using a Craig-Gordon model, we demonstrate that leaf water in the growth chamber grasses should have experienced significant D-enriched due to transpiration. Nonetheless, we found no effect of transpirational D-enrichment on the ?D l values. In field samples, we saw clear evidence of enrichment (correlating with relative humidity of the field sites) in both ?18O C and ?D l. These seemingly contrasting results could be explained if leaf waxes are synthesized in an environment that is isotopically similar to water entering plant roots due to either temporal or spatial isolation from evaporatively enriched leaf waters. For grasses in the controlled environment, there was no enrichment of source water, whereas enrichment of grass source water via evaporation from soils and/or stems was likely for grass samples grown in the field. Based on these results, evaporation from soils and/or stems appears to affect ?D l, but transpiration from leaves does not. Further evidence for this conclusion is found in modeling expected net evapotranspirational enrichment. A Craig-Gordon model applied to each of the field sites yields leaf water oxygen isotope ratios that can be used to accurately predict the observed ?18O C values. In contrast, the calculated leaf water hydrogen isotope ratios are more enriched than what is required to predict observed ?D l values. These calculations lend support to the conclusion that while ?18O C reflects both soil evaporation and transpiration, ?D l appears to only record evaporation from soils and/or stems. Therefore, the ?D of n-alkanes can likely be used to reconstruct the ?D of water entering a leaf, supporting the soil-enrichment model of Smith and Freeman (2006). In both the field and controlled studies, we found significant photosynthetic pathway effects on n-alkane ?D suggesting that biochemical pathways or plant phylogeny have a greater effect on leaf wax ?D than leaf-water enrichment in grasses.

  7. CFD-BASED AEROSERVOELASTIC PREDICTIONS ON A BENCHMARK CONFIGURATION USING THE TRANSPIRATION METHOD

    E-print Network

    Jacob, Jamey

    CFD-BASED AEROSERVOELASTIC PREDICTIONS ON A BENCHMARK CONFIGURATION USING THE TRANSPIRATION METHOD the Transpiration Method by Cole H. Stephens. Known Errors: · Pages 62-64: [TJC] The derivation outlined on pages 62

  8. Rate variation in parasitic plants: correlated and uncorrelated patterns among plastid genes of different function

    PubMed Central

    Young, Nelson D; dePamphilis, Claude W

    2005-01-01

    Background The analysis of synonymous and nonsynonymous rates of DNA change can help in the choice among competing explanations for rate variation, such as differences in constraint, mutation rate, or the strength of genetic drift. Nonphotosynthetic plants of the Orobanchaceae have increased rates of DNA change. In this study 38 taxa of Orobanchaceae and relatives were used and 3 plastid genes were sequenced for each taxon. Results Phylogenetic reconstructions of relative rates of sequence evolution for three plastid genes (rbcL, matK and rps2) show significant rate heterogeneity among lineages and among genes. Many of the non-photosynthetic plants have increases in both synonymous and nonsynonymous rates, indicating that both (1) selection is relaxed, and (2) there has been a change in the rate at which mutations are entering the population in these species. However, rate increases are not always immediate upon loss of photosynthesis. Overall there is a poor correlation of synonymous and nonsynonymous rates. There is, however, a strong correlation of synonymous rates across the 3 genes studied and the lineage-speccific pattern for each gene is strikingly similar. This indicates that the causes of synonymous rate variation are affecting the whole plastid genome in a similar way. There is a weaker correlation across genes for nonsynonymous rates. Here the picture is more complex, as could be expected if there are many causes of variation, differing from taxon to taxon and gene to gene. Conclusions The distinctive pattern of rate increases in Orobanchaceae has at least two causes. It is clear that there is a relaxation of constraint in many (though not all) non-photosynthetic lineages. However, there is also some force affecting synonymous sites as well. At this point, it is not possible to tell whether it is generation time, speciation rate, mutation rate, DNA repair efficiency or some combination of these factors. PMID:15713237

  9. Initiating Event Rates at U.S. Nuclear Power Plants 1988–2013

    SciTech Connect

    John A. Schroeder; Gordon R. Bower

    2014-02-01

    Analyzing initiating event rates is important because it indicates performance among plants and also provides inputs to several U.S. Nuclear Regulatory Commission (NRC) risk-informed regulatory activities. This report presents an analysis of initiating event frequencies at U.S. commercial nuclear power plants since each plant’s low-power license date. The evaluation is based on the operating experience from fiscal year 1988 through 2013 as reported in licensee event reports. Engineers with nuclear power plant experience staff reviewed each event report since the last update to this report for the presence of valid scrams or reactor trips at power. To be included in the study, an event had to meet all of the following criteria: includes an unplanned reactor trip (not a scheduled reactor trip on the daily operations schedule), sequence of events starts when reactor is critical and at or above the point of adding heat, occurs at a U.S. commercial nuclear power plant (excluding Fort St. Vrain and LaCrosse), and is reported by a licensee event report. This report displays occurrence rates (baseline frequencies) for the categories of initiating events that contribute to the NRC’s Industry Trends Program. Sixteen initiating event groupings are trended and displayed. Initiators are plotted separately for initiating events with different occurrence rates for boiling water reactors and pressurized water reactors. p-values are given for the possible presence of a trend over the most recent 10 years.

  10. Effects of floral display size and plant density on pollinator visitation rate in a natural population of Digitalis purpurea

    Microsoft Academic Search

    J. M. GRINDELAND; N. SLETVOLD; R. A. IMS

    2005-01-01

    Summary 1. Pollinator visitation patterns in relation to variation in floral display size may be modified both quantitatively and qualitatively by local plant density. In this study four measures of pollinator response by Bombus spp. (plant visitation rate, bout length, proportion of flowers visited, flower visitation rate) were investigated under two or three different plant densities in two consecutive years

  11. A thermal method for measuring the rate of water movement in plants

    E-print Network

    Bloodworth, Morris Elkins

    1958-01-01

    ??8??A??8 ????A??AoB??? B? ?8?A ?B????AoB? B? ?A?Ao? ?A8? Figure 8. Heat transfer in the stem of a cotton plant before and after removal of the top G A LV A N O M ET ER D E FL E C TI O N 31 60 ? 50 _ 40 ? EFFECT OF REMOVING PLANT..., Effect of thermistor location on a cotton plant stem as related to water movement rates 14 0 G O X CL 2u! o ? to CM IO 1 0) IO IO Q. zUi X > < = ?? _l _l w _l o < a: 2 < ?? ?o ro t ______I co Ui...

  12. BroadScale Analysis Contradicts the Theory That Generation Time Affects Molecular Evolutionary Rates in Plants

    Microsoft Academic Search

    Carrie-Ann Whittle; Mark O. Johnston

    2003-01-01

      Abstract\\u000a \\u000a Several studies of plant taxa have concluded that generation time, including annual\\/perennial life history, may explain molecular\\u000a evolutionary rate variation in selectively neutral DNA. Unlike in animals, there is little theoretical basis for why generation-time\\u000a effects would exist in plants. Furthermore, previous reports fail to establish the generality of a generation-time effect\\u000a in plants because of the small size

  13. Enhanced transpiration by riparian buffer trees in response to advection in a humid temperate agricultural landscape

    USGS Publications Warehouse

    Hernandez-Santana, V.; Asbjornsen, H.; Sauer, T.; Isenhart, T.; Schilling, K.; Schultz, Ronald

    2011-01-01

    Riparian buffers are designed as management practices to increase infiltration and reduce surface runoff and transport of sediment and nonpoint source pollutants from crop fields to adjacent streams. Achieving these ecosystem service goals depends, in part, on their ability to remove water from the soil via transpiration. In these systems, edges between crop fields and trees of the buffer systems can create advection processes, which could influence water use by trees. We conducted a field study in a riparian buffer system established in 1994 under a humid temperate climate, located in the Corn Belt region of the Midwestern U.S. (Iowa). The goals were to estimate stand level transpiration by the riparian buffer, quantify the controls on water use by the buffer system, and determine to what extent advective energy and tree position within the buffer system influence individual tree transpiration rates. We primarily focused on the water use response (determined with the Heat Ratio Method) of one of the dominant species (Acer saccharinum) and a subdominant (Juglans nigra). A few individuals of three additional species (Quercus bicolor, Betula nigra, Platanus occidentalis) were monitored over a shorter time period to assess the generality of responses. Meteorological stations were installed along a transect across the riparian buffer to determine the microclimate conditions. The differences found among individuals were attributed to differences in species sap velocities and sapwood depths, location relative to the forest edge and prevailing winds and canopy exposure and dominance. Sapflow rates for A. saccharinum trees growing at the SE edge (prevailing winds) were 39% greater than SE interior trees and 30% and 69% greater than NW interior and edge trees, respectively. No transpiration enhancement due to edge effect was detected in the subdominant J. nigra. The results were interpreted as indicative of advection effects from the surrounding crops. Further, significant differences were document in sapflow rates between the five study species, suggesting that selection of species is important for enhancing specific riparian buffer functions. However, more information is needed on water use patterns among diverse species growing under different climatic and biophysical conditions to assist policy and management decisions regarding effective buffer design. ?? 2011.

  14. On the Representativeness of Plot Size and Location for Scaling Transpiration from Trees to a Stand

    Microsoft Academic Search

    D. Scott Mackay; Brent E. Ewers; Michael M. Loranty; Eric L. Kruger

    2010-01-01

    Scaling transpiration from trees to larger areas is a fundamental problem in ecohydrology. For scaling stand transpiration from sap flux sensors we asked if plot representativeness depended on plot size and location, the magnitude of environmental drivers, parameter needs for ecosystem models, and whether the goal was to estimate transpiration per unit ground area (EC), per unit leaf area (EL),

  15. On the representativeness of plot size and location for scaling transpiration from trees to a stand

    Microsoft Academic Search

    D. Scott Mackay; Brent E. Ewers; Michael M. Loranty; Eric L. Kruger

    2010-01-01

    Scaling transpiration from trees to larger areas is a fundamental problem in ecohydrology. For scaling stand transpiration from sap flux sensors we asked if plot representativeness depended on plot size and location, the magnitude of environmental drivers, parameter needs for ecosystem models, and whether the goal was to estimate transpiration per unit ground area (EC), per unit leaf area (EL),

  16. Integrated Analysis for the Design of Reusable TPS based on Variable Transpiration Cooling for Hypersonic Cruise

    E-print Network

    Texas at Arlington, University of

    1 Integrated Analysis for the Design of Reusable TPS based on Variable Transpiration Cooling systems have to be considered in order to afford long duration flights in hypersonic regime. Transpiration to simulate uniform transpiration. A saw-tooth wall velocity distribution is used to simulate the variable

  17. PHYSICAL REVIEW E 86, 036311 (2012) Macroscopic description of nonequilibrium effects in thermal transpiration

    E-print Network

    Bahrami, Majid

    transpiration flows in annular microchannels Peyman Taheri and Majid Bahrami Laboratory for Alternative Energy transpiration flow of rarefied gases in annular channels is considered where the driving force for the flow it thermal transpiration flow. At the same time, Maxwell [4] was trying to provide a microscopic description

  18. Satellite-based modeling of transpiration from the grasslands in the Southern Great Plains, USA

    E-print Network

    Pielke, Roger A.

    Satellite-based modeling of transpiration from the grasslands in the Southern Great Plains, USA Project IHOP_2002 Southern Great Plains Vegetation Transpiration Model Vegetation Photosynthesis Model evaporation transpiration Data from the 2002 International H2O Project (IHOP_2002), which was conducted during

  19. Original article Tree canopy and herb layer transpiration in three Scots

    E-print Network

    Paris-Sud XI, Université de

    Original article Tree canopy and herb layer transpiration in three Scots pine stands with different - To evaluate the impact of herb layer structure on the transpiration of Scots pine ecosystems in north-eastern Germany, we measured tree canopy and herb layer transpiration in three stands. Parameters of tree

  20. Author's personal copy Satellite-based modeling of transpiration from the grasslands in the Southern Great

    E-print Network

    Niyogi, Dev

    Author's personal copy Satellite-based modeling of transpiration from the grasslands (MODIS) 2002 International H2O Project IHOP_2002 Southern Great Plains Vegetation Transpiration Model Vegetation Photosynthesis Model evaporation transpiration Data from the 2002 International H2O Project (IHOP

  1. American Institute of Aeronautics and Astronautics Investigation of Transpiration Cooling Effectiveness for Air-

    E-print Network

    Texas at Arlington, University of

    American Institute of Aeronautics and Astronautics 1 Investigation of Transpiration Cooling in this paper is focused on transpiration cooling and investigates the effects of fluid injection the transpiration cooling along a flat plate. The reduced order code is intended to assess the boundary layer

  2. Control of transpiration in a 220-year-old Abies amabilis forest T.A. Martina,*

    E-print Network

    Martin, Timothy

    Control of transpiration in a 220-year-old Abies amabilis forest T.A. Martina,* , K.J. Browna,1 , J 2000 Abstract We measured sap ¯ow at the branch and tree levels, and calculated tree transpiration growth stand transpired approximately three times more per day (up to 281 kg H2O per day) than dominant

  3. ForPeerReview Tree diversity enhances tree transpiration in a Panamanian

    E-print Network

    Bermingham, Eldredge

    ForPeerReview Tree diversity enhances tree transpiration in a Panamanian forest plantation Journal-species stands, monoculture, native species, plot transpiration, selection effect Journal of Applied Ecology #12;ForPeerReview 1 Tree diversity enhances tree transpiration in a Panamanian forest plantation1 2

  4. Effect of vertical resolution on predictions of transpiration in water-limited ecosystems

    E-print Network

    Guswa, Andrew J.

    Effect of vertical resolution on predictions of transpiration in water-limited ecosystems Andrew J the vegetation root zone. Average transpiration in such environments is controlled by precipitation, and accurate of vertical resolution on predictions of transpiration, we conduct a series of numerical experiments

  5. Dynamics of transpiration and evaporation following a moisture pulse in semiarid grassland: A chamber-based

    E-print Network

    Williams, David G.

    Dynamics of transpiration and evaporation following a moisture pulse in semiarid grassland, the short-term (15-day) dynamics of transpiration (T) and evaporation (E) in experimental replicated stands of stand transpiration from the Keeling plot chamber method were positively correlated (Pearson's r = 0

  6. Tree and stand transpiration in a Midwestern bur oak savanna after elm encroachment and restoration thinning

    E-print Network

    Tree and stand transpiration in a Midwestern bur oak savanna after elm encroachment and restoration) to quantify transpiration in an Iowa bur oak (Quercus macrocarpa) savanna woodland encroached by elms (Ulmus, the woodland's stand transpiration was greater (1.23 mm dayÃ?1 ) than the savanna's (0.35 mm dayÃ?1 ), yet

  7. A simple method for estimating water loss by transpiration in wetlands

    Microsoft Academic Search

    SALVADOR SÂNCHEZ-CARRILLO; MIGUEL ÂLVAREZ-COBELAS; MANUEL BENITEZ; DAVID G. ANGELER

    Estimates of transpiration are often needed for hydrological management in wetlands. A new and simple method, using a portable steady-state porometer, is presented for estimating transpiration in three aquatic emergent macrophytes (reed, cut-sedge, and cattail). The method was established on the basis of the relationships between transpiration, solar radiation, relative humidity and air temperature. By assessing relationships between all variables

  8. Cooling Duct Analysis for Transpiration/Film Cooled Liquid Propellant Rocket Engines

    NASA Technical Reports Server (NTRS)

    Micklow, Gerald J.

    1996-01-01

    The development of a low cost space transportation system requires that the propulsion system be reusable, have long life, with good performance and use low cost propellants. Improved performance can be achieved by operating the engine at higher pressure and temperature levels than previous designs. Increasing the chamber pressure and temperature, however, will increase wall heating rates. This necessitates the need for active cooling methods such as film cooling or transpiration cooling. But active cooling can reduce the net thrust of the engine and add considerably to the design complexity. Recently, a metal drawing process has been patented where it is possible to fabricate plates with very small holes with high uniformity with a closely specified porosity. Such a metal plate could be used for an inexpensive transpiration/film cooled liner to meet the demands of advanced reusable rocket engines, if coolant mass flow rates could be controlled to satisfy wall cooling requirements and performance. The present study investigates the possibility of controlling the coolant mass flow rate through the porous material by simple non-active fluid dynamic means. The coolant will be supplied to the porous material by series of constant geometry slots machined on the exterior of the engine.

  9. Transpiration-Cooled Spacecraft-Insulation-Repair Fasteners

    NASA Technical Reports Server (NTRS)

    Camarda, Charles J.; Pettit, Donald R.; Glass, David; Scotti, Stephen J.; Vaughn, Wallace Lee; Rawal, Suraj

    2012-01-01

    Transpiration-cooled fasteners are proposed that operate like an open-loop heat pipe (self-tapping screws, bolts, and spikes) for use in on-orbit repair of thermal- insulation of a space shuttle or other spacecraft. By limiting the temperature rise of such a fastener and of the adjacent repair material and thermal protection system, the transpiration cooling would contribute to the ability of the repair to retain its strength and integrity in the high-heat-flux, oxidizing environment of reentry into the atmosphere of the Earth. A typical fastener according to the proposal would include a hollow refractory-metal, refractory-composite, or ceramic screw or bolt, the central cavity of which would be occupied by a porous refractory- metal or ceramic plug that would act as both a reservoir and a wick for a transpirant liquid. The plug dimensions, the plug material, and the sizes of the pores would be chosen in conjunction with the transpirant liquid so that (1) capillary pumping could be relied upon to transport the liquid to the heated surface, where the liquid would be vaporized, and (2) the amount of liquid would suffice for protecting against the anticipated heat flux and integrated heat load.

  10. The competition between liquid and vapor transport in transpiring leaves.

    PubMed

    Rockwell, Fulton Ewing; Holbrook, N Michele; Stroock, Abraham Duncan

    2014-04-01

    In leaves, the transpirational flux of water exits the veins as liquid and travels toward the stomata in both the vapor and liquid phases before exiting the leaf as vapor. Yet, whether most of the evaporation occurs from the vascular bundles (perivascular), from the photosynthetic mesophyll cells, or within the vicinity of the stomatal pore (peristomatal) remains in dispute. Here, a one-dimensional model of the competition between liquid and vapor transport is developed from the perspective of nonisothermal coupled heat and water molecule transport in a composite medium of airspace and cells. An analytical solution to the model is found in terms of the energy and transpirational fluxes from the leaf surfaces and the absorbed solar energy load, leading to mathematical expressions for the proportions of evaporation accounted for by the vascular, mesophyll, and epidermal regions. The distribution of evaporation in a given leaf is predicted to be variable, changing with the local environment, and to range from dominantly perivascular to dominantly peristomatal depending on internal leaf architecture, with mesophyll evaporation a subordinate component. Using mature red oak (Quercus rubra) trees, we show that the model can be solved for a specific instance of a transpiring leaf by combining gas-exchange data, anatomical measurements, and hydraulic experiments. We also investigate the effect of radiation load on the control of transpiration, the potential for condensation on the inside of an epidermis, and the impact of vapor transport on the hydraulic efficiency of leaf tissue outside the xylem. PMID:24572172

  11. CONTROLS ON TRANSPIRATION IN A DESERT RIPARIAN COTTONWOOD FOREST 1764

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cottonwood (Populus spp.) forests are conspicuous and functionally important elements of riparian vegetation throughout much of the western U.S. Understanding how transpiration of this vegetation type responds to environmental forcing is important for determining the water balance dynamics of ripar...

  12. Adapting FAO-56 Spreadsheet Program to estimate olive orchard transpiration fluxes under soil water stress condition

    NASA Astrophysics Data System (ADS)

    Rallo, G.; Provenzano, G.; Manzano-Juárez, J.

    2012-04-01

    In the Mediterranean environment, where the period of crops growth does not coincide with the rainy season, the crop is subject to water stress periods that may be amplified with improper irrigation management. Agro-hydrological models can be considered an economic and simple tool to optimize irrigation water use, mainly when water represents a limiting factor for crop production. In the last two decades, agro-hydrological physically based models have been developed to simulate mass and energy exchange processes in the soil-plant-atmosphere system (Feddes et al., 1978; Bastiaanssen et al., 2007). Unfortunately these models, although very reliable, as a consequence of the high number of required variables and the complex computational analysis, cannot often be used. Therefore, simplified agro-hydrological models may represent an useful and simple tool for practical irrigation scheduling. The main objective of the work is to assess, for an olive orchard, the suitability of FAO-56 spreadsheet agro-hydrological model to estimate a long time series of field transpiration, soil water content and crop water stress dynamic. A modification of the spreadsheet is suggested in order to adapt the simulations to a crop tolerant to water stress. In particular, by implementing a new crop water stress function, actual transpiration fluxes and an ecophysiological stress indicator, i. e. the relative transpiration, are computed in order to evaluate a plant-based irrigation scheduling parameter. Validation of the proposed amendment is carried out by means of measured sap fluxes, measured on different plants and up-scaled to plot level. Spatial and temporal variability of soil water contents in the plot was measured, at several depths, using the Diviner 2000 capacitance probe (Sentek Environmental Technologies, 2000) and TDR-100 (Campbell scientific, Inc.) system. The detailed measurements of soil water content, allowed to explore the high spatial variability of soil water content due to the combined effect of the punctual irrigation and the non-uniform root density distribution. A further validation of the plant-based irrigation-timing indicator will be carried out by considering another ecophysiological stress variable like the predawn leaf water potential. Accuracy of the model output was assessed using the Mean Absolute Difference, the Root Mean Square Difference and the efficiency index of Nash and Sutcliffe. Experimental data, recorded during three years of field observation, allowed, with a great level of detail, to investigate on the dynamic of water fluxes from the soil to atmosphere as well as to validate the proposed amendment of the FAO-56 spreadsheet. The modified model simulated with a satisfactory approximation the measured values of average soil water content in the root zone, with error of estimation equal to about 2.0%. These differences can be considered acceptable for practical applications taking into account the intrinsic variability of the data especially in the soil moisture point measurements. An error less than 1 mm was calculated in the daily transpiration estimation. A good performance was observed in the estimation of the cumulate transpiration fluxes.

  13. Effect of Expansion of Fertilization Width on Nitrogen Recovery Rate in Tea Plants

    NASA Astrophysics Data System (ADS)

    Nonaka, Kunihiko; Hirono, Yuhei; Watanabe, Iriki

    In cultivation of tea plants, large amounts of nitrogen, compared to amounts used for other crops, have been used for fertilization, resulting in degradation of the soil environment between hedges and an increase in concentrations of nitrate nitrogen in surrounding water systems. To reduce the environmental load, new methods of fertilizer application are needed. This report deals with the effect of expansion of fertilization width on nitrogen recovery rate in tea plants. In the test field, 15 N-labeled ammonium sulfate had been applied over custom fertilization by between-hedges fertilization (fertilization width of 15cm) and wide fertilization (fertilization width of 40cm), nitrogen recovery rates were compared. Expansion of fertilization width resulted in an approximately 30% increase in nitrogen recovery rate compared to that in the case of fertilization between hedges. Increases in nitrogen recovery rates were observed with fallapplied fertilization, spring-applied fertilization, pop-up fertilizer application, and summerapplied fertilization.

  14. Studies of shock/shock interaction on smooth and transpiration-cooled hemispherical nosetips in hypersonic flow

    NASA Technical Reports Server (NTRS)

    Holden, Michael S.; Rodriguez, Kathleen M.

    1992-01-01

    A program of experimental research and analysis was conducted to examine the heat transfer and pressure distributions in regions of shock/shock interaction over smooth and transpiration-cooled hemispherical noseshapes. The objective of this investigation was to determine whether the large heat transfer generated in regions of shock/shock interaction can be reduced by transpiration cooling. The experimental program was conducted at Mach numbers of 12 to 16 in the Calspan 48-Inch Shock Tunnel. Type 3 and type 4 interaction regions were generated for a range of freestream unit Reynolds numbers to provide shear layer Reynolds numbers from 10 exp 4 to 10 exp 6 to enable laminar and turbulent interaction regions to be studied. Shock/shock interactions were investigated on a smooth hemispherical nosetip and a similar transpiration-cooled nosetip, with the latter configuration being examined for a range of surface blowing rates up to one-third of the freestream mass flux. While the heat transfer measurements on the smooth hemisphere without shock/shock interaction were in good agreement with Fay-Riddell predictions, those on the transpiration-cooled nosetip indicated that its intrinsic roughness caused heating-enhancement factors of over 1.5. In the shock/shock interaction studies on the smooth nosetip, detailed heat transfer and pressure measurements were obtained to map the variation of the distributions with shock-impingement position for a range of type 3 and type 4 interactions. Such sets of measurements were obtained for a range of unit Reynolds numbers and Mach numbers to obtain both laminar and turbulent interactions. The measurements indicated that shear layer transition has a significant influence on the heating rates for the type 4 interaction as well as the anticipated large effects on type 3 interaction heating. In the absence of blowing, the peak heating in the type 3 and type 4 interaction regions, over the transpiration-cooled model, did not appear to be influenced by the model's rough surface characteristics. The studies of the effects of the transpiration cooling on type 3 and type 4 shock/shock interaction regions demonstrated that large surface blowing rates had significant effect on the structure of the flowfield, enlarging the shock layer and moving the region of peak-heating interaction around the body.

  15. The use of ionisation chambers for dose rate measurements at industrial irradiation plants

    Microsoft Academic Search

    J. P Sephton; P. H. G Sharpe; R. D. H Chu

    2002-01-01

    The use of ionisation chambers to measure dose rate at industrial irradiation plants has been studied as part of a wider project on real time dosimetry. The characteristics required of such a chamber are discussed. These include the ability to withstand operation at high cumulative doses (up to 5MGy) and dose rates of up to about 150kGyh?1. Other desirable features

  16. Simulation of Water Transport in the Soil-Plant - System.

    NASA Astrophysics Data System (ADS)

    Guo, Yimei

    1992-01-01

    The objective of this dissertation is to develop a mechanistic model of water transport in the soil-plant -atmosphere system that describes the plant's physical expression of water stress to study the effects of environmental factors, and plant hydraulic and physical properties on plant water transport. The model includes soil moisture uptake, soil heat and water transfer, evapotranspiration, and energy partitioning in the canopy and at the soil surface. The model inputs are: daily weather data (air temperature, dew point temperature, wind speed, and solar radiation); initial soil moisture and temperature profiles; plant characteristics; root density; and soil hydraulic properties. The model user may select from a number of outputs. Principal outputs include: leaf resistance, leaf temperature, soil moisture profile and evapotranspiration rate. The model describes a feedback mechanism by which transpiration controls leaf water potential, leaf water potential influences leaf resistance, and leaf resistance which, in turn, controls transpiration. The simulation runs represented the energy partitioning in the canopy and at the soil surface, and the diurnal variation of temperatures and vapor pressures of the leaf, the canopy air, and the soil surface. The relationships of leaf water potential to soil water potential, leaf resistance and transpiration were also presented. In addition, results show that root water extraction is related to the root length density profile and the soil moisture profile. The model mechanistically describes the water transport in the soil-plant-atmosphere system. The results of model validation indicated that the model is capable of simulating plant water transport under natural conditions with reasonable accuracy. Results show that the model simulates the basic features of the system including feedback processes. The sensitivity studies show that the model may be used to study plant water response to environmental factors and plant properties. The model is also useful for estimating evapotranspiration and the soil moisture profile and may provide information for irrigation and soil water management. (Abstract shortened with permission of author.).

  17. Somatic deleterious mutation rate in a woody plant: estimation from phenotypic data

    PubMed Central

    Bobiwash, K; Schultz, S T; Schoen, D J

    2013-01-01

    We conducted controlled crosses in populations of the long-lived clonal shrub, Vaccinium angustifolium (lowbush blueberry) to estimate inbreeding depression and mutation parameters associated with somatic deleterious mutation. Inbreeding depression level was high, with many plants failing to set fruit after self-pollination. We also compared fruit set from autogamous pollinations (pollen collected from within the same inflorescence) with fruit set from geitonogamous pollinations (pollen collected from the same plant but from inflorescences separated by several meters of branch growth). The difference between geitonogamous versus autogamous fitness within single plants is referred to as ‘autogamy depression' (AD). AD can be caused by somatic deleterious mutation. AD was significantly different from zero for fruit set. We developed a maximum-likelihood procedure to estimate somatic mutation parameters from AD, and applied it to geitonogamous and autogamous fruit set data from this experiment. We infer that, on average, approximately three sublethal, partially dominant somatic mutations exist within the crowns of the plants studied. We conclude that somatic mutation in this woody plant results in an overall genomic deleterious mutation rate that exceeds the rate measured to date for annual plants. Some implications of this result for evolutionary biology and agriculture are discussed. PMID:23778990

  18. The Correlation of Evolutionary Rate with Pathway Position in Plant Terpenoid Biosynthesis

    E-print Network

    Rieseberg, Loren

    in fact correlate with pathway position along pathways converting glucose to the terpenoid phytohormonesThe Correlation of Evolutionary Rate with Pathway Position in Plant Terpenoid Biosynthesis Heather pathways, because upstream genes are more pleiotropic, being required for a wider range of end products

  19. Effect of Seeding Rate and Planting Arrangement on Rye Cover Crop and Weed Growth

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Weed growth in winter cover crops in warm climates may contribute to weed management costs in subsequent crops. A two year experiment was conducted on an organic vegetable farm in Salinas, California, to determine the impact of seeding rate and planting arrangement on rye (Secale cereale L. cv. Merc...

  20. Effect of frequency of dosing of plant sterols on plasma cholesterol levels and synthesis rate

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective was to compare the effects of plant sterols (PS) consumed as a single dose (single) at breakfast or as three doses consumed with breakfast, lunch and dinner (divided) on plasma lipoprotien levels and cholesterol endogenous fractional synthesis rate (FSR). A randomized, placebo-controll...

  1. Coal flow aids reduce coke plant operating costs and improve production rates

    SciTech Connect

    Bedard, R.A.; Bradacs, D.J.; Kluck, R.W.; Roe, D.C.; Ventresca, B.P.

    2005-06-01

    Chemical coal flow aids can provide many benefits to coke plants, including improved production rates, reduced maintenance and lower cleaning costs. This article discusses the mechanisms by which coal flow aids function and analyzes several successful case histories. 2 refs., 10 figs., 1 tab.

  2. The Effect of Differential Growth Rates across Plants on Spectral Predictions of Physiological Parameters

    PubMed Central

    Rapaport, Tal; Hochberg, Uri; Rachmilevitch, Shimon; Karnieli, Arnon

    2014-01-01

    Leaves of various ages and positions in a plant's canopy can present distinct physiological, morphological and anatomical characteristics, leading to complexities in selecting a single leaf for spectral representation of an entire plant. A fortiori, as growth rates between canopies differ, spectral-based comparisons across multiple plants – often based on leaves' position but not age – becomes an even more challenging mission. This study explores the effect of differential growth rates on the reflectance variability between leaves of different canopies, and its implication on physiological predictions made by widely-used spectral indices. Two distinct irrigation treatments were applied for one month, in order to trigger the formation of different growth rates between two groups of grapevines. Throughout the experiment, the plants were physiologically and morphologically monitored, while leaves from every part of their canopies were spectrally and histologically sampled. As the control vines were constantly developing new leaves, the water deficit plants were experiencing growth inhibition, resulting in leaves of different age at similar nodal position across the treatments. This modification of the age-position correlation was characterized by a near infrared reflectance difference between younger and older leaves, which was found to be exponentially correlated (R2?=?0.98) to the age-dependent area of intercellular air spaces within the spongy parenchyma. Overall, the foliage of the control plant became more spectrally variable, creating complications for intra- and inter-treatment leaf-based comparisons. Of the derived indices, the Structure-Insensitive Pigment Index (SIPI) was found indifferent to the age-position effect, allowing the treatments to be compared at any nodal position, while a Normalized Difference Vegetation Index (NDVI)-based stomatal conductance prediction was substantially affected by differential growth rates. As various biotic and abiotic factors may form distinctions in growth, future precision agriculture studies should consider its spectral effect on physiological predictions. PMID:24523946

  3. Numerical analysis of gas separator with thermal transpiration in micro channels II

    NASA Astrophysics Data System (ADS)

    Nakaye, Shoeji; Sugimoto, Hiroshi

    2014-12-01

    A membrane gas separator which operates with only a small temperature difference across a membrane is designed, and its capability is numerically proved. The separator system consists of three Knudsen pumps - a motionless pump that utilizes the thermal transpiration of the rarefied gas. Each pump is composed of a porous membrane and one channel along each of the two surfaces of the membrane. Two of the pumps induce a variation of mole fraction using a combination of the thermal transpiration and pressure driven flow through the membrane, and the other one provides the former two pumps with a required pressure difference. This paper reports the first numerical calculations that demonstrate a neon-argon binary gas mixture can be separated into pure neon gas and argon gas with the proposed design. The temperature difference is no more than 90 K, and the total length of the membrane is ˜ 15 cm at standard ambient temperature and pressure. The production rate of the separator is proportional to the width of the membrane. For example, when the width is 10 cm, the flow rates of the product gases are 0.8 sccm for argon and 1.9 sccm for neon.

  4. Association between Residential Proximity to Fuel-Fired Power Plants and Hospitalization Rate for Respiratory Diseases

    PubMed Central

    Liu, Xiaopeng; Lessner, Lawrence

    2012-01-01

    Background: Air pollution is known to cause respiratory disease. Unlike motor vehicle sources, fuel-fired power plants are stationary. Objective: Using hospitalization data, we examined whether living near a fuel-fired power plant increases the likelihood of hospitalization for respiratory disease. Methods: Rates of hospitalization for asthma, acute respiratory infection (ARI), and chronic obstructive pulmonary disease (COPD) were estimated using hospitalization data for 1993–2008 from New York State in relation to data for residences near fuel-fired power plants. We also explored data for residential proximity to hazardous waste sites. Results: After adjusting for age, sex, race, median household income, and rural/urban residence, there were significant 11%, 15%, and 17% increases in estimated rates of hospitalization for asthma, ARI, and COPD, respectively, among individuals > 10 years of age living in a ZIP code containing a fuel-fired power plant compared with one that had no power plant. Living in a ZIP code with a fuel-fired power plant was not significantly associated with hospitalization for asthma or ARI among children < 10 years of age. Living in a ZIP code with a hazardous waste site was associated with hospitalization for all outcomes in both age groups, and joint effect estimates were approximately additive for living in a ZIP code that contained a fuel-fired power plant and a hazardous waste site. Conclusions: Our results are consistent with the hypothesis that exposure to air pollution from fuel-fired power plants and volatile compounds coming from hazardous waste sites increases the risk of hospitalization for respiratory diseases. PMID:22370087

  5. Improved growth, productivity and quality of tomato (Solanum lycopersicum L.) plants through application of shikimic acid

    PubMed Central

    Al-Amri, Salem M.

    2013-01-01

    A field experiment was conducted to investigate the effect of seed presoaking of shikimic acid (30, 60 and 120 ppm) on growth parameters, fruit productivity and quality, transpiration rate, photosynthetic pigments and some mineral nutrition contents of tomato plants. Shikimic acid at all concentrations significantly increased fresh and dry weights, fruit number, average fresh and dry fruit yield, vitamin C, lycopene, carotenoid contents, total acidity and fruit total soluble sugars of tomato plants when compared to control plants. Seed pretreatment with shikimic acid at various doses induces a significant increase in total leaf conductivity, transpiration rate and photosynthetic pigments (Chl. a, chl. b and carotenoids) of tomato plants. Furthermore, shikimic acid at various doses applied significantly increased the concentration of nitrogen, phosphorus and potassium in tomato leaves as compared to control non-treated tomato plants. Among all doses of shikimic acid treatment, it was found that 60 ppm treatment caused a marked increase in growth, fruit productivity and quality and most studied parameters of tomato plants when compared to other treatments. On the other hand, no significant differences were observed in total photosynthetic pigments, concentrations of nitrogen and potassium in leaves of tomato plants treated with 30 ppm of shikimic acid and control plants. According to these results, it could be suggested that shikimic acid used for seed soaking could be used for increasing growth, fruit productivity and quality of tomato plants growing under field conditions. PMID:24235870

  6. Multi-Objective Parameter Estimation for Simulating Canopy Transpiration in Forested Watersheds

    NASA Astrophysics Data System (ADS)

    Mackay, D. S.; Samanta, S.

    2002-12-01

    Transpiration is a major component flux simulated by distributed land surface process models. However, the uncertainty of parameterizing leaf stomatal function at a large scale represents a significant gap in characterizing physiological responses to climate change and land use pressures. A fuzzy logic parameter estimation technique is first applied to the simulation of four forest stands in northern Wisconsin, using a half-hourly Jarvis-based model of stomatal conductance calibrated to sap flux measurements. Parameterizations for the multiple species are shown to strictly follow plant hydraulics with a linear relationship between stomatal sensitivity to the log of vapor pressure deficit, dGs/lnD, and reference conductance, Gsref, with a slope of 0.6. Plant species falling on this line theoretically regulate water potential to just prevent runaway cavitation. The multi-objective technique is then extended to a series of 25 hillslopes in a Central Sierra Nevada watershed, using a daily model calibrated to thermal remote sensing data acquired at times of both high and low soil moisture. Initially, only canopy parameters are adjusted. Under well-watered conditions the estimated dGs/lnD versus Gsref among all hillslopes follows the same linear relation of slope 0.6. It is then shown that by adding a scalar of vegetation rooting length into the parameter estimation scheme, dGs/lnD versus Gsref among hillslopes also conforms to the theory for water-stressed conditions. The results point to potential use of remote sensing for quantifying plant hydraulic controls on transpiration at regional to global scales.

  7. Transpiration cooled electrodes and insulators for MHD generators

    DOEpatents

    Hoover, Jr., Delmer Q. (Churchill Boro, PA)

    1981-01-01

    Systems for cooling the inner duct walls in a magnetohydrodynamic (MHD) generator. The inner face components, adjacent the plasma, are formed of a porous material known as a transpiration material. Selected cooling gases are transpired through the duct walls, including electrically insulating and electrode segments, and into the plasma. A wide variety of structural materials and coolant gases at selected temperatures and pressures can be utilized and the gases can be drawn from the generation system compressor, the surrounding environment, and combustion and seed treatment products otherwise discharged, among many other sources. The conduits conducting the cooling gas are electrically insulated through low pressure bushings and connectors so as to electrically isolate the generator duct from the ground.

  8. PGEN: an integrated model of leaf photosynthesis, transpiration, and conductance

    Microsoft Academic Search

    A. D. Friend

    1995-01-01

    A detailed model of leaf-scale photosynthesis, respiration, transpiration, stomatal conductance, and energy balance is described. The model, PGEN v2.0 11The code is available from the author upon request., is designed for use in larger-scale ecosystem, climate and hydrological models concerned with fluxes of CO2, water, and heat. Given a set of environmental and biological (mostly leaf) parameters, PGEN calculates instantaneous

  9. DSMC Simulation of thermal transpiration and accomodation pumps

    SciTech Connect

    Hudson, M.L.; Bartel, T.J.

    1998-11-01

    The Direct Simulation Monte Carlo (DSMC) technique is employed to evaluate several configurations of thermal transpiration and accommodation pumps. There is renewed interest in these rarefied flow pumping concepts for Micro-Electro-Mechanical Systems (MEMS) due to advances in micro-fabrication. The simulation results are compared with existing data to understand gas-surface interaction uncertainties in the experiments. Parametric studies are performed to determine the effects of Knudsen number and surface temperature and roughness on the maximum pump pressure ratio.

  10. Transpiration of cottonwood\\/willow forest estimated from sap flux

    Microsoft Academic Search

    Sean M. Schaeffer; David G. Williams; David C. Goodrich

    2000-01-01

    Cottonwood\\/willow forests in the American Southwest consist of discrete, even-aged vegetation patches arranged in narrow strips along active and abandoned stream channels of alluvial flood plains. We used the heat-pulse velocity technique in this study to estimate transpiration in 12 such forest patches along a perennially flowing reach of the San Pedro River in southeastern Arizona, USA during five periods

  11. Study of deposition control using transpiration. Technical progress report

    SciTech Connect

    Louis, J.F.; Kozlu, H.

    1985-01-01

    The purpose of this project is to determine the conditions under which transpiration may be actually used to avoid the deposition of small particles. The application of this work is the control of the deposition of small particles over a surface kept at a temperature below the melting point of compounds likely to exist in the combustion products. A combined experimental and theoretical research program will be carried out to evaluate the concept of transpiration as a deposition control strategy. A first order theory will be refined by introducing an appropriate turbulence model. The experimental program is designed to evaluate and refine the theoretical model under conditions which provide the correct Reynolds and Stokes numbers. The experimental setup consists of a wind tunnel with a test section containing a flat porous transpired section. The measurements will determine the distribution of velocity and of particle concentration in the boundary layer. The experiments will be conducted for different particle sizes under conditions simulating gas turbine conditions.

  12. Study of deposition control using transpiration. Technical progress report

    SciTech Connect

    Louis, J.F.; Kozlu, H.

    1986-03-01

    The purpose of this project is to determine the conditions under which transpiration may be actually used to avoid deposition of small particles. The application of this work is the control of the deposition of small particles over a surface kept at a temperature below the melting point of compounds likely to exist in the combustion products. A combined experimental and theoretical research program will be carried out to evaluate the concept of transpiration as a deposition control strategy. A first order theory will be refined by introducing an appropriate turbulence model. The experimental program is designed to evaluate and refine the theoretical model under conditions which provide the correct Reynolds and Stokes numbers. The experimental set up consists of a wind tunnel with a test section containing a flat porous transpired section. The measurements will determine the distribution of velocity and of particle concentration in the boundary layer. The experiments will be conducted for different particle sizes under conditions sumulating gas turbine conditions.

  13. Development of saline ground water through transpiration of sea water.

    PubMed

    Fass, T; Cook, P G; Stieglitz, T; Herczeg, A L

    2007-01-01

    As vegetation usually excludes salt during water uptake, transpiration will increase the salinity of the residual water. If the source water is sea water, then the residual water may become highly saline. In the unconfined coastal aquifer of the tropical Burdekin River delta, northeastern Australia, areas of highly saline ground water with chloride concentrations up to almost three times that of sea water occur up to 15 km from the present coastline, and are attributed to transpiration by mangrove vegetation during periods of high sea level. Radiogenic ((14)C) carbon isotope analyses indicate that ground water with chloride concentrations between 15,000 and 35,000 mg/L is mostly between 4000 and 6000 years old, at which time sea level was 2 to 3 m higher than present. Stable isotope analyses of oxygen-18 and deuterium show no evidence for evaporative enrichment of this water. Oxygen-18, deuterium, and stable (delta(13)C) carbon isotope analyses of ground water and soil water point to a recharge environment beneath the mangrove forests during this postglacial sea level high stand. During that period, transpiration of the mangrove forests would have led to high chloride concentrations in the residual ground water, without inducing isotopic fractionation. Due to the higher density, this hypersaline water moved downward through the aquifer by gravity and has formed lenses of highly saline ground water at the bottom of the unconfined aquifer. PMID:17973748

  14. Porous Ceramic Coating for Transpiration Cooling of Gas Turbine Blade

    NASA Astrophysics Data System (ADS)

    Arai, M.; Suidzu, T.

    2013-06-01

    A transpiration cooling system for gas turbine applications has significant benefit for reducing the amount of cooling air and increasing cooling efficiency. In this paper, the porous ceramic coating, which can infiltrate cooling gas, is developed with plasma spraying process, and the properties of the porous coating material such as permeability of cooling gas, thermal conductivity, and adhesion strength are examined. The mixture of 8 wt.% yttria-stabilized zirconia and polyester powders was employed as the coating material, in order to deposit the porous ceramic coating onto Ni-based super alloy substrate. It was shown that the porous ceramic coating has superior permeability for cooling gas. The adhesion strength of the porous coating was low only 20% compared with the thermal barrier coating utilized in current gas turbine blades. Simulation test of hot gas flow around the gas turbine blade verified remarkable reduction of the coating surface temperature by the transpiration cooling mechanism. It was concluded that the transpiration cooling system for the gas turbine could be achieved using the porous ceramic coating developed in this study.

  15. Supplementary documentation for an Environmental Impact Statement regarding the Pantex Plant: a comparison of county and state cancer mortality rates

    Microsoft Academic Search

    L. D. Wiggs; G. S. Wilkinson; G. L. Tietjen; J. F. Acquavella

    1982-01-01

    This report documents work performed in support of preparation of an Environmental Impact Statement (EIS) regarding the Department of Energy's Pantex Plant near Amarillo, Texas. This report considers cancer mortality rates in the region surrounding the Pantex nuclear weapons facility. The working hypothesis was that increased cancer mortality rates would exist in counties proximal to the Pantex Plant. To evaluate

  16. Extinction rate estimates for plant populations in revisitation studies: Importance of detectability

    USGS Publications Warehouse

    Kery, M.

    2004-01-01

    Many researchers have obtained extinction-rate estimates for plant populations by comparing historical and current records of occurrence. A population that is no longer found is assumed to have gone extinct. Extinction can then be related to characteristics of these populations, such as habitat type, size, or species, to test ideas about what factors may affect extinction. Such studies neglect the fact that a population may be overlooked, however, which may bias estimates of extinction rates upward. In addition, if populations are unequally detectable across groups to be compared, such as habitat type or population size, comparisons become distorted to an unknown degree. To illustrate the problem, I simulated two data sets, assuming a constant extinction rate, in which populations occurred in different habitats or habitats of different size and these factors affected their detectability The conventional analysis implicitly assumed that detectability equalled 1 and used logistic regression to estimate extinction rates. It wrongly identified habitat and population size as factors affecting extinction risk. In contrast, with capture-recapture methods, unbiased estimates of extinction rates were recovered. I argue that capture-recapture methods should be considered more often in estimations of demographic parameters in plant populations and communities.

  17. The effect of land plants on weathering rates of silicate minerals

    SciTech Connect

    Drever, J.I. (Univ. of Wyoming, Laramie, WY (United States))

    1994-05-01

    Land plants and their associated microbiota directly affect silicate mineral weathering in several ways: by generation of chelating ligands, by modifying pH through production of CO[sub 2] or organic acids, and by altering the physical properties of a soil, particularly the exposed surface areas of minerals and the residence time of water. In laboratory experiments far from equilibrium, 1 mM oxalate (a strong chelator of Al) has a negligible effect on the dissolution rate of alkali feldspars, but some effect on calcic feldspars and olivine. By analogy to oxalate, the overall effect of organic ligands on the weathering rate of silicate minerals in nature is likely to be small, except perhaps in microenvironments adjacent to roots and fungal hyphae. The effect of pH on silicate mineral dissolution rate depends on pH: below pH 4-5, the rate increases with decreasing pH, in the circumneutral region the rate is pH-independent, and at pH values above around 8 the rate increases with increasing pH. Vegetation should thus cause an increase in weathering rate through the pH effect only where the pH is below 4-5. As an overall generalization, the effect of plants on weathering rate through changes in soil-solution chemistry is probably small for granitic rocks; it may be greater for more mafic rocks. It is the release of Ca and Mg from mafic rocks that has the greatest influence on the global CO[sub 2] budget.

  18. Photosynthesis in intact leaves of C 3 plants: Physics, physiology and rate limitations

    Microsoft Academic Search

    Thomas D. Sharkey

    1985-01-01

    The instantaneous rate of photosynthetic CO2 assimilation in C3 plants has generally been studied in model systems such as isolated chloroplasts and algae. From these studies and from theoretical\\u000a analyses of gas exchange behavior it is now possible to study the biochemistry of photosynthesis in intact leaves using a\\u000a combination of methods, most of which are nondestructive.\\u000a \\u000a The limitations to

  19. Estimation of Rates of Recombination and Migration in Populations of Plant Pathogens?A Reply

    Microsoft Academic Search

    J. Zhan; C. C. Mundt; B. A. McDonald

    2000-01-01

    Zhan, J., Mundt, C. C., and McDonald, B. A. 2000. Estimation of rates of recombination and migration in populations of plant pathogens —A reply. Phytopathology 90:324-326. We find that the maximum likelihood method proposed by J. K. M. Brown has deficiencies that limit its usefulness for actual data sets. We propose two alternative statistical methods based on maximum likelihood that

  20. Hazard rating of ash and slag dumps of thermal power plants firing Kuznetskii coal

    SciTech Connect

    E.P. Dik; A.N. Soboleva [All-Russia Thermal Engineering Institute (VTI), Moscow (Russian Federation)

    2006-03-15

    Results of a study of the degree of toxicity and of the hazard rating of ash and slag waste due to firing Kuznetskii coals at thermal power plants are presented. Computation shows and biological tests prove that the waste belongs to the fifth hazard class, i.e., is virtually safe. Comparison of the results obtained with foreign data shows that the waste in question belongs to the safe category in accordance with foreign standards as well.

  1. Enhanced IGCC regulatory control and coordinated plant-wide control strategies for improving power ramp rates

    SciTech Connect

    Mahapatra, P.; Zitney, S.

    2012-01-01

    As part of ongoing R&D activities at the National Energy Technology Laboratory’s (NETL) Advanced Virtual Energy Simulation Training & Research (AVESTAR™) Center, this paper highlights strategies for enhancing low-level regulatory control and system-wide coordinated control strategies implemented in a high-fidelity dynamic simulator for an Integrated Gasification Combined Cycle (IGCC) power plant with carbon capture. The underlying IGCC plant dynamic model contains 20 major process areas, each of which is tightly integrated with the rest of the power plant, making individual functionally-independent processes prone to routine disturbances. Single-loop feedback control although adequate to meet the primary control objective for most processes, does not take into account in advance the effect of these disturbances, making the entire power plant undergo large offshoots and/or oscillations before the feedback action has an opportunity to impact control performance. In this paper, controller enhancements ranging from retuning feedback control loops, multiplicative feed-forward control and other control techniques such as split-range control, feedback trim and dynamic compensation, applicable on various subsections of the integrated IGCC plant, have been highlighted and improvements in control responses have been given. Compared to using classical feedback-based control structure, the enhanced IGCC regulatory control architecture reduces plant settling time and peak offshoots, achieves faster disturbance rejection, and promotes higher power ramp-rates. In addition, improvements in IGCC coordinated plant-wide control strategies for “Gasifier-Lead”, “GT-Lead” and “Plantwide” operation modes have been proposed and their responses compared. The paper is concluded with a brief discussion on the potential IGCC controller improvements resulting from using advanced process control, including model predictive control (MPC), as a supervisory control layer.

  2. Ozone uptake and effects on transpiration, net photosynthesis, and dark respiration in Scots pine. [Pinus sylvestris L

    SciTech Connect

    Skaerby, L.; Troeng, E.; Bostroem, C.

    1987-09-01

    Ozone uptake, transpiration, net photosynthesis, and dark respiration were studied in the field by using an open gas exchange system in a 20-year-old stand of Scots pine (Pinus sylvestris L.). A current shoot was treated with ozone concentrations ranging from 120 to 400 ..mu..g x m/sup -3/ during one month. During daytime there was a linear relationship between ozone concentration and ozone uptake, and the deposition rate varied between 0.05 and 0.13 cm x s/sup -1/. Ozone at the highest concentrations seemed to decrease transpiration somewhat during daytime. At night, ozone was taken up only at the highest concentration. Both transpiration and stomatal conductance increased at night when ozone concentration was 250..mu..g x m/sup -3/ and higher. There was no significant influence on the net photosynthetic performance during exposure to ozone. Dark respiration, however, increased throughout the experimental period, and the accumulated respiration was about 60% higher for the ozone-exposed shoot at the end of the experiment.

  3. Transpiration and water use efficiency in native chilean and exotic species, a usefull tool for catchment management?

    NASA Astrophysics Data System (ADS)

    Hervé-Fernández, P.; Oyarzun, C. E.

    2012-04-01

    Land-use and forest cover change play important roles in socio-economic processes and have been linked with water supply and other ecosystem services in various regions of the world. Water yield from watersheds is a major ecosystem service for human activities but has been altered by landscape management superimposed on climatic variability and change. Sustaining ecosystem services important to humans, while providing a dependable water supply for agriculture and urban needs is a major challenge faced by managers of human-dominated or increased antropical effect over watersheds. Since water is mostly consumed by vegetation (i.e: transpiration), which strongly depends on trees physiological characteristics (i.e: foliar area, transpiration capacity) are very important. The quantity of water consumed by plantations is influenced mainly by forest characteristics (species physiology, age and management), catchment water retention capacity and meteorological characteristics. Eventhough in Chile, the forest sector accounts for 3.6% of the gross domestic product (GDP) and 12.5% of total exports (INFOR, 2003), afforestation with fast growing exotic species has ended up being socially and politically questionable because of the supposed impact on the environment and water resources. We present data of trees transpiration and water use efficiency from three headwater catchments: (a) second growth native evergreen forest (Aetoxicon punctatum, Drimys winterii, Gevuina avellana, Laureliopsis philippiana); (b) Eucalyptus globulus plantation, and (c) a mixed native deciduous (Nothofagus obliqua and some evergreen species) forest and Eucalyptus globulus and Acacia melanoxylon plantation located at the Coastal Mountain Range in southern Chile (40°S). Annual transpiration rates ranged from 1.24 ± 0.41 mol•m-2•s-1 (0.022 ± 0.009 L•m-2•s-1) for E. globulus, while the lowest observed was for L. philippiana 0.44 ± 0.31 mol•m-2•s-1 (0.008 ± 0.006 L•m-2•s-1). However water use efficiency for E. globulus, was the lowest observed (6.78 ± 8.92 ?mol•mol-1) compared to native species, 7.45 ± 4.41 ?mol•mol-1 for A. punctatum which showed the lowest value (p < 0.05). Preliminary results show, that the E. globulus has the highest transpiration rate, but the lowest water use efficiency values, compared to native evergreen and deciduous species. Nevertheless E. globulus showed the highest photosyntethic rate values, which finally traduces that E. globulus is a fast growing, big water drinker but it's less efficient than most native trees used in this experiment. Acknowledges This research has been supported by FONDECYT 1090345. Mr. Hervé-Fernández wishes to thank BECAS CHILE for his scholarship.

  4. Life history influences rates of climatic niche evolution in flowering plants

    PubMed Central

    Smith, Stephen A.; Beaulieu, Jeremy M.

    2009-01-01

    Across angiosperms, variable rates of molecular substitution are linked with life-history attributes associated with woody and herbaceous growth forms. As the number of generations per unit time is correlated with molecular substitution rates, it is expected that rates of phenotypic evolution would also be influenced by differences in generation times. Here, we make the first broad-scale comparison of growth-form-dependent rates of niche evolution. We examined the climatic niches of species on large time-calibrated phylogenies of five angiosperm clades and found that woody lineages have accumulated fewer changes per million years in climatic niche space than related herbaceous lineages. Also, climate space explored by woody lineages is consistently smaller than sister lineages composed mainly of herbaceous taxa. This pattern is probably linked to differences in the rate of climatic niche evolution. These results have implications for niche conservatism; in particular, the role of niche conservatism in the distribution of plant biodiversity. The consistent differences in the rate of climatic niche evolution also emphasize the need to incorporate models of phenotypic evolution that allow for rate heterogeneity when examining large datasets. PMID:19776076

  5. Determining water use by trees and forests from isotopic, energy balance and transpiration analyses: the roles of tree size and hydraulic lift.

    PubMed

    Dawson, Todd E.

    1996-01-01

    Use of soil water and groundwater by open-grown Acer saccharum Marsh. (sugar maple) tree canopies and forests was estimated by measuring transpiration (E) rates using porometry, sap flow methods, and the Bowen ratio method. The Bowen ratio and sap flow methods showed the best agreement; porometer measurements scaled to whole canopies always underestimated E by 15-50%. Trees of different sizes showed very different rates of E. I hypothesized that these differences were due to the differential access of large and small trees to groundwater and soil water, respectively. Transpirational flux was partitioned between soil water and groundwater by tracing the water sources based on their hydrogen stable isotopic composition (deltaD). Soil water deltaD varied between -41 and -16 per thousand seasonally (May to September), whereas groundwater deltaD was -79 +/- 5 per thousand during the entire growing season. Daily transpiration rates of large (9-14 m tall) trees were significantly higher than those of small (3-5 m tall) trees (2.46-6.99 +/- 1.02-2.50 versus 0.69-1.80 +/- 0.39-0.67 mm day(-1)). Small trees also showed greater variation in E during the growing season than large trees. In addition, compared to the large trees, small trees demonstrated greater sensitivity to environmental factors that influence E, such as soil water deficits and increased evaporative demand. Over the entire growing season, large trees and forest stands composed of trees > 10 m tall transpired only groundwater. The high rates of water loss from large trees and older forests were likely a result of the influence of an enhanced "pool" of transpirational water in the upper soil layers caused by hydraulic lift (see Dawson 1993b). The hydraulically lifted water reservoir enabled large trees to use more potential transpirational water during daylight hours than small trees, leading to a greater total water flux. In contrast, small trees and forest stands composed of younger trees almost exclusively used soil water, except during two dry periods when their transpirational water was composed of between 7 and 17% groundwater. Thus groundwater discharge from sugar maple trees and forest stands of different sizes (ages) differs significantly, and large trees and older forest stands have a greater impact on the hydrologic balance of groundwater than small trees and younger forest stands. However, mixed stands (small and large trees) may have a greater overall impact on the regional hydrologic balance than old stands, because trees in mixed stands draw on both soil water and groundwater reservoirs and thus can substantially increase total water discharge on scales from tens to hundreds of hectares. PMID:14871771

  6. Cyclic variations in nitrogen uptake rate of soybean plants: ammonium as a nitrogen source

    NASA Technical Reports Server (NTRS)

    Henry, L. T.; Raper, C. D. Jr

    1989-01-01

    When NO3- is the sole nitrogen source in flowing solution culture, the net rate of nitrogen uptake by nonnodulated soybean (Glycine max L. Merr. cv Ransom) plants cycles between maxima and minima with a periodicity of oscillation that corresponds with the interval of leaf emergence. Since soybean plants accumulate similar quantities of nitrogen when either NH4+ or NO3- is the sole source in solution culture controlled at pH 6.0, an experiment was conducted to determine if the oscillations in net rate of nitrogen uptake also occur when NH4+ is the nitrogen source. During a 21-day period of vegetative development, net uptake of NH4+ was measured daily by ion chromatography as depletion of NH4+ from a replenished nutrient solution containing 1.0 millimolar NH4+. The net rate of NH4+ uptake oscillated with a periodicity that was similar to the interval of leaf emergence. Instances of negative net rates of uptake indicate that the transition between maxima and minima involved changes in influx and efflux components of net NH4+ uptake.

  7. Island radiation on a continental scale: Exceptional rates of plant diversification after uplift of the Andes

    PubMed Central

    Hughes, Colin; Eastwood, Ruth

    2006-01-01

    Species radiations provide unique insights into evolutionary processes underlying species diversification and patterns of biodiversity. To compare plant diversification over a similar time period to the recent cichlid fish radiations, which are an order of magnitude faster than documented bird, arthropod, and plant radiations, we focus on the high-altitude flora of the Andes, which is the most species-rich of any tropical mountains. Because of the recent uplift of the northern Andes, the upland environments where much of this rich endemic flora is found have been available for colonization only since the late Pliocene or Pleistocene, 2–4 million years (Myr) ago. Using DNA sequence data we identify a monophyletic group within the genus Lupinus representing 81 species endemic to the Andes. The age of this clade is estimated to be 1.18–1.76 Myr, implying a diversification rate of 2.49–3.72 species per Myr. This exceeds previous estimates for plants, providing the most spectacular example of explosive plant species diversification documented to date. Furthermore, it suggests that the high cichlid diversification rates are not unique. Lack of key innovations associated with the Andean Lupinus clade suggests that diversification was driven by ecological opportunities afforded by the emergence of island-like habitats after Andean uplift. Data from other genera indicate that lupines are one of a set of similarly rapid Andean plant radiations, continental in scale and island-like in stimulus, suggesting that the high-elevation Andean flora provides a system that rivals other groups, including cichlids, for understanding rapid species diversification. PMID:16801546

  8. Fire and Grazing Influences on Rates of Riparian Woody Plant Expansion along Grassland Streams

    PubMed Central

    Veach, Allison M.; Dodds, Walter K.; Skibbe, Adam

    2014-01-01

    Grasslands are threatened globally due to the expansion of woody plants. The few remaining headwater streams within tallgrass prairies are becoming more like typical forested streams due to rapid conversion of riparian zones from grassy to wooded. Forestation can alter stream hydrology and biogeochemistry. We estimated the rate of riparian woody plant expansion within a 30 m buffer zone surrounding the stream bed across whole watersheds at Konza Prairie Biological Station over 25 years from aerial photographs. Watersheds varied with respect to experimentally-controlled fire and bison grazing. Fire frequency, presence or absence of grazing bison, and the historical presence of woody vegetation prior to the study time period (a proxy for proximity of propagule sources) were used as independent variables to predict the rate of riparian woody plant expansion between 1985 and 2010. Water yield was estimated across these years for a subset of watersheds. Riparian woody encroachment rates increased as burning became less frequent than every two years. However, a higher fire frequency (1–2 years) did not reverse riparian woody encroachment regardless of whether woody vegetation was present or not before burning regimes were initiated. Although riparian woody vegetation cover increased over time, annual total precipitation and average annual temperature were variable. So, water yield over 4 watersheds under differing burn frequencies was quite variable and with no statistically significant detected temporal trends. Overall, burning regimes with a frequency of every 1–2 years will slow the conversion of tallgrass prairie stream ecosystems to forested ones, yet over long time periods, riparian woody plant encroachment may not be prevented by fire alone, regardless of fire frequency. PMID:25192194

  9. Fire and grazing influences on rates of riparian woody plant expansion along grassland streams.

    PubMed

    Veach, Allison M; Dodds, Walter K; Skibbe, Adam

    2014-01-01

    Grasslands are threatened globally due to the expansion of woody plants. The few remaining headwater streams within tallgrass prairies are becoming more like typical forested streams due to rapid conversion of riparian zones from grassy to wooded. Forestation can alter stream hydrology and biogeochemistry. We estimated the rate of riparian woody plant expansion within a 30 m buffer zone surrounding the stream bed across whole watersheds at Konza Prairie Biological Station over 25 years from aerial photographs. Watersheds varied with respect to experimentally-controlled fire and bison grazing. Fire frequency, presence or absence of grazing bison, and the historical presence of woody vegetation prior to the study time period (a proxy for proximity of propagule sources) were used as independent variables to predict the rate of riparian woody plant expansion between 1985 and 2010. Water yield was estimated across these years for a subset of watersheds. Riparian woody encroachment rates increased as burning became less frequent than every two years. However, a higher fire frequency (1-2 years) did not reverse riparian woody encroachment regardless of whether woody vegetation was present or not before burning regimes were initiated. Although riparian woody vegetation cover increased over time, annual total precipitation and average annual temperature were variable. So, water yield over 4 watersheds under differing burn frequencies was quite variable and with no statistically significant detected temporal trends. Overall, burning regimes with a frequency of every 1-2 years will slow the conversion of tallgrass prairie stream ecosystems to forested ones, yet over long time periods, riparian woody plant encroachment may not be prevented by fire alone, regardless of fire frequency. PMID:25192194

  10. Evaluation of transpiration in a Douglas-fir stand by means of sap flow measurements

    Microsoft Academic Search

    A. GRANIER

    1987-01-01

    Transpiration of a Douglas-fir (Pseudorsuga menziesii (Mirb.) France) stand was evaluated by sap flow measurements during a 4-month period. Between-tree variation in sap flow depended on crown class. On a sunny day, total transpiration was 1.6, 8.0 and 22.0 liters day-' for suppressed, codomi- nant and dominant trees, respectively. Transpiration estimated by sap How fell below potential evapotranspiration when available

  11. Crown conductance and tree and stand transpiration in a second-growth Abies amabilis

    E-print Network

    Martin, Timothy

    Crown conductance and tree and stand transpiration in a second-growth Abies amabilis forest T-area basis) of 0.57 mm·s­1 and transpiring up to 4.9 kg·day­1 , while the largest tree measured had%) of the variation in gcrown. The dominant and codominant trees in the stand transpired for longer periods during

  12. Atmospheric Pb and Ti accumulation rates from Sphagnum moss: dependence upon plant productivity.

    PubMed

    Kempter, H; Krachler, M; Shotyk, W

    2010-07-15

    The accumulation rates of atmospheric Pb and Ti were obtained using the production rates of Sphagnum mosses collected in four ombrotrophic bogs from two regions of southern Germany: Upper Bavaria (Oberbayern, OB) and the Northern Black Forest (Nordschwarzwald, NBF). Surfaces of Sphagnum carpets were marked with plastic mesh and one year later the production of plant matter was harvested. Metal concentrations were determined in acid digests using sector field ICP-MS employing well established analytical procedures. Up to 12 samples (40 x 40 cm) were collected per site, and 6-10 sites were investigated per bog. Variations within a given sampling site were in the range 2.3-4x for Pb concentrations, 1.8-2.5x for Ti concentrations, 3-8.3x for Pb/Ti, 5.6-7.8x for Pb accumulation rates, and 2.3-6.4x for Ti accumulation rates. However, the median values of these parameters for the sites (6-10 per bog) were quite consistent. The mosses from the bogs in NBF exhibited significantly greater productivity (187-202 g m(-2) a(-1)) compared to the OB peat bogs (71-91 g m(-2) a(-1)), and these differences had a pronounced effect on the Pb and Ti accumulation rates. Highly productive mosses showed no indication of a "dilution effect" of Pb or Ti concentrations, suggesting that more productive plants were simply able to accumulate more particles from the air. The median rates of net Pb accumulation by the mosses are in excellent agreement with the fluxes obtained by direct atmospheric measurements at nearby monitoring stations in both regions (EMEP and MAPESI data). PMID:20545344

  13. Plant N capture from pulses: effects of pulse size, growth rate, and other soil resources.

    PubMed

    James, J J; Richards, J H

    2005-08-01

    In arid ecosystems, the ability to rapidly capture nitrogen (N) from brief pulses is expected to influence plant growth, survival, and competitive ability. Theory and data suggest that N capture from pulses should depend on plant growth rate and availability of other limiting resources. Theory also predicts trade-offs in plant stress tolerance and ability to capture N from different size pulses. We injected K15NO3, to simulate small and large N pulses at three different times during the growing season into soil around the co-dominant Great Basin species Sarcobatus vermiculatus, Chrysothamnus nauseosus ssp. consimilis, and Distichlis spicata. Soils were amended with water and P in a partial factorial design. As predicted, all study species showed a comparable decline in N capture from large pulses through the season as growth rates slowed. Surprisingly, however, water and P availability differentially influenced the ability of these species to capture N from pulses. Distichlis N capture increased up to tenfold with water addition while Chrysothamnus N capture increased up to threefold with P addition. Sarcobatus N capture was not affected by water or P availability. Opposite to our prediction, Sarcobatus, the most stress tolerant species, captured less N from small pulses but more N from large pulses relative to the other species. These observations suggest that variation in N pulse timing and size can interact with variable soil water and P supply to determine how N is partitioned among co-existing Great Basin species. PMID:16003506

  14. Simultaneous monitoring of electrical capacitance and water uptake activity of plant root system

    NASA Astrophysics Data System (ADS)

    Cseresnyés, Imre; Takács, Tünde; Füzy, Anna; Rajkai, Kálmán

    2014-10-01

    Pot experiments were designed to test the applicability of root electrical capacitance measurement for in situ monitoring of root water uptake activity by growing cucumber and bean cultivars in a growth chamber. Half of the plants were inoculated with Funneliformis mosseae arbuscular mycorrhizal fungi, while the other half served as non-infected controls. Root electrical capacitance and daily transpiration were monitored during the whole plant ontogeny. Phenology-dependent changes of daily transpiration (related to root water uptake) and root electrical capacitance proved to be similar as they showed upward trends from seedling emergence to the beginning of flowering stage, and thereafter decreased continuously during fruit setting. A few days after arbuscular mycorrhizal fungi-colonization, daily transpiration and root electrical capacitance of infected plants became significantly higher than those of non-infected counterparts, and the relative increment of the measured parameters was greater for the more highly mycorrhizal-dependent bean cultivar compared to that of cucumber. Arbuscular mycorrhizal fungi colonization caused 29 and 69% relative increment in shoot dry mass for cucumbers and beans, respectively. Mycorrhization resulted in 37% increase in root dry mass for beans, but no significant difference was observed for cucumbers. Results indicate the potential of root electrical capacitance measurements for monitoring the changes and differences of root water uptake rate.

  15. Labile soil carbon inputs mediate the soil microbial community composition and plant residue decomposition rates

    SciTech Connect

    De Graaff, Marie-Anne [ORNL; Classen, Aimee T [University of Tennessee, Knoxville (UTK); Castro Gonzalez, Hector F [ORNL; Schadt, Christopher Warren [ORNL

    2010-01-01

    Root carbon (C) inputs may regulate decomposition rates in soil, and in this study we ask: how do labile C inputs regulate decomposition of plant residues, and soil microbial communities? In a 14 d laboratory incubation, we added C compounds often found in root exudates in seven different concentrations (0, 0.7, 1.4, 3.6, 7.2, 14.4 and 21.7 mg C g{sup -1} soil) to soils amended with and without {sup 13}C-labeled plant residue. We measured CO{sub 2} respiration and shifts in relative fungal and bacterial rRNA gene copy numbers using quantitative polymerase chain reaction (qPCR). Increased labile C input enhanced total C respiration, but only addition of C at low concentrations (0.7 mg C g{sup -1}) stimulated plant residue decomposition (+2%). Intermediate concentrations (1.4, 3.6 mg C g{sup -1}) had no impact on plant residue decomposition, while greater concentrations of C (> 7.2 mg C g{sup -1}) reduced decomposition (-50%). Concurrently, high exudate concentrations (> 3.6 mg C g{sup -1}) increased fungal and bacterial gene copy numbers, whereas low exudate concentrations (< 3.6 mg C g{sup -1}) increased metabolic activity rather than gene copy numbers. These results underscore that labile soil C inputs can regulate decomposition of more recalcitrant soil C by controlling the activity and relative abundance of fungi and bacteria.

  16. The oxygen isotopic compositions of silica phytoliths and plant water in grasses: implications for the study of paleoclimate

    NASA Astrophysics Data System (ADS)

    Webb, Elizabeth A.; Longstaffe, Frederick J.

    2000-03-01

    Information about climatic conditions during plant growth is preserved by the oxygen-isotope composition of biogenic silica (phytoliths) deposited in grasses. The oxygen-isotope composition of phytolith silica is dependent on soil-water ? 18O values, relative humidity and evapotranspiration, and temperature during plant growth. Phytolith and plant-water ? 18O values for C3 ( A. breviligulata) and C4 ( C. longifolia) grasses from natural and greenhouse sites in southwestern Ontario were used to compare the isotopic fractionation between biogenic silica and water in various parts of these living plants. For non or weakly transpiring tissues (rhizomes, stems, sheaths) in both grass species, the ? 18O silica-plant water remained constant at ˜34‰, and the ? 18O and ?D values of plant water collected from pre-dawn and mid-day samplings showed little variation. These plant waters were only slightly enriched in 18O and D relative to water provided to the grasses. Isotopic temperatures calculated from the silica and plant-water isotopic data matched measured growing temperatures for the region. By comparison, the upper leaf water was extremely enriched in oxygen-18 and deuterium at maximum rates of transpiration relative to water from non-transpiring tissues, as were the calculated, steady-state values for leaf-water ? 18O and ?D. Silica produced in the transpiring tissues (leaf, inflorescence) has higher ? 18O values than silica from non-transpiring tissues, but the enrichment is modest compared to upper leaf water under mid-day conditions. Leaf phytoliths have formed from plant water typical of average conditions in the lower leaf, where the extreme 18O-enrichment is not encountered. C. longifolia was also collected from Alberta and Nebraska, where growing conditions are different from southwestern Ontario. Phytoliths at all three sites have a similar pattern of ? 18O values within the plants, but the isotopic separation between leaf and stem silica increases from 4 to 8‰ as average relative humidity decreases. The difference between actual growing temperature and that calculated using measured ? 18O values for stem silica and local meteoric water became progressively larger as relative humidity decreased, likely because of evaporative 18O-enrichment of soil water. Such effects are most pronounced in arid environments and pertinent in grasslands where much of the active rooting zone can be situated at the shallower depths most affected by the 18O-enrichment of soil water.

  17. Joint estimation of contemporary seed and pollen dispersal rates among plant populations.

    PubMed

    Robledo-Arnuncio, J J

    2012-03-01

    There are few statistical methods for estimating contemporary dispersal among plant populations. A maximum-likelihood procedure is introduced here that uses pre- and post-dispersal population samples of biparentally inherited genetic markers to jointly estimate contemporary seed and pollen immigration rates from a set of discrete external sources into a target population. Monte Carlo simulations indicate that accurate estimates and reliable confidence intervals can be obtained using this method for both pollen and seed migration rates at modest sample sizes (100 parents/population and 100 offspring) when population differentiation is moderate (F(ST) ? 0.1), or by increasing pre-dispersal samples (to about 500 parents/population) when genetic divergence is weak (F(ST) = 0.01). The method exhibited low sensitivity to the number of source populations and achieved good accuracy at affordable genetic resolution (10 loci with 10 equifrequent alleles each). Unsampled source populations introduced positive biases in migration rate estimates from sampled sources, although they were minor when the proportion of immigration from the latter was comparatively low. A practical application of the method to a metapopulation of the Australian resprouter shrub Banksia attenuata revealed comparable levels of directional seed and pollen migration among dune groups, and the estimate of seed dispersal was higher than a previous estimate based on conservative assignment tests. The method should be of interest to researchers and managers assessing broad-scale nonequilibrium seed and pollen gene flow dynamics in plants. PMID:22085307

  18. Transpiration cooling in the locality of a transverse fuel jet for supersonic combustors

    NASA Technical Reports Server (NTRS)

    Northam, G. Burton; Capriotti, Diego P.; Byington, Carl S.

    1990-01-01

    The objective of the current work was to determine the feasibility of transpiration cooling for the relief of the local heating rates in the region of a sonic, perpendicular, fuel jet of gaseous hydrogen. Experiments were conducted to determine the interaction between the cooling required and flameholding limits of a transverse jet in a high-enthalpy, Mach 3 flow in both open-jet and direct-connect test mode. Pulsed shadowgraphs were used to illustrate the flow field. Infrared thermal images indicated the surface temperatures, and the OH(-) emission of the flame was used to visualize the limits of combustion. Wall, static presures indicated the location of the combustion within the duct and were used to calculate the combustion efficiency. The results from both series of tests at facility total temperatures of 1700 K and 2000 K are presented.

  19. Wire Cloth as Porous Material for Transpiration-cooled Walls

    NASA Technical Reports Server (NTRS)

    Eckert, E R G; Kinsler, Martin R; Cochran, Reeves B

    1951-01-01

    The permeability characteristics and tensile strength of a porous material developed from stainless-steel corduroy wire cloth for use in transpiration-cooled walls where the primary stresses are in one direction were investigated. The results of this investigation are presented and compared with similar results obtained with porous sintered metal compacts. A much wider range of permeabilities is obtainable with the wire cloth than with the porous metal compacts considered and the ultimate tensile strength in the direction of the primary stresses for porous materials produced from three mesh sizes of wire cloth are from two to three times the ultimate tensile strengths of the porous metal compacts.

  20. A contribution of groundwater to Mojave Desert shrub transpiration

    SciTech Connect

    Hunter, R.B.

    1988-12-31

    Soil moisture was measured to 1-m depths in the northern Mojave Desert on two plots, one of which was denuded of shrubs. The pattern of wetting-drying near the surface and below the depth wet by rainfall suggested roughly 2 mm per month of transpired water was supplied by percolation upward from below the root zone. This deep moisture built up during fall and winter and depleted in spring and summer, which correlates well with local shrub phenology. 10 refs., 3 figs.

  1. Effect of kinetic boundary condition on the thermal transpiration coefficient

    NASA Astrophysics Data System (ADS)

    Sugimoto, Hiroshi; Amakawa, Kenjiro

    2014-12-01

    The effect of kinetic boundary condition on the free molecular thermal transpiration coefficient ? is analyzed numerically. The Maxwell model boundary condition is applied in its original form in the sense that its accommodation coefficient depends on the speed of incident molecules. The results show that the value of ? depends much on the velocity dependency of the accommodation coefficient. The experimental result, ? < 0.5, can be reproduced if the grazing molecules reflect diffusely. This makes a sharp contrast with the previous works that ? =0.5 for the velocity independent accommodation coefficient.

  2. Thermal/structural analysis of a transpiration cooled nozzle

    NASA Technical Reports Server (NTRS)

    Gregory, Peyton B.; Thompson, Jon E.; Babcock, Dale A.; Gray, Carl E., Jr.; Mouring, Chris A.

    1992-01-01

    The 8-foot High Temperature Tunnel (HTT) at LaRC is a combustion driven, high enthalpy blow down wind tunnel. In Mar. 1991, during check out of the transpiration cooled nozzle, pieces of platelets were found in the tunnel test section. It was determined that incorrect tolerancing between the platelets and the housing was the primary cause of the platelet failure. An analysis was performed to determine the tolerance layout between the platelets and the housing to meet the structural and performance criteria under a range of thermal, pressure, and bolt preload conditions. Three recommendations resulted as a product of this analysis.

  3. Control and Augmentation of Passive Porosity through Transpiration Control

    NASA Technical Reports Server (NTRS)

    Banks, Daniel W. (Inventor); Wood, Richard M. (Inventor); Bauer, Steven X. S. (Inventor)

    1999-01-01

    A device for controlling pressure loading of a member caused by a fluid moving past the member or the member moving through a fluid. The device consists of a porous skin mounted over the solid surface of the member and separated from the solid surface by a plenum. Fluid from an area exerting high pressure on the member may enter the plenum through the porous surface and exit into an area exerting a lower pressure on the member, thus controlling pressure loading of the member. A transpirational control device controls the conditions within the plenum thus controlling the side force and yaw moment on the forebody.

  4. How to help woody plants to overcome drought stress?-a control study of four tree species in Northwest China.

    NASA Astrophysics Data System (ADS)

    Liu, Xiaozhen; Zhang, Shuoxin

    2010-05-01

    Water is essential for plants and involves most physical and chemical processes within their lifecycles. Drought stress is a crucial limiting factor for plant growth and production. 48% of the land in China is arid and semi-arid, and non-irrigated land occupies approximately 51.9% of the total cultivated areas. Therefore, studies on plant drought resistant mechanisms have great significance for improving water use efficiency and thus increasing productivity of economical plants. Prior research has shown that the application of nitrogenous fertilizer affects the drought-resistant characteristics of plants. This study aimed to reveal the effect of nitrogenous fertilizer on physiological aspects and its impact on the drought resistance of four tree species (Robinia pseudoacacia L., Ligustrum lucidum Ait., Acer truncatum Bge. and Ulmus pumila L. ) in northwest China. Three levels of nitrogen fertilization (46% N based of urea adjusted to: 5g/15g soil, 15g/15g soil and 25g/15g soil) and an additional control study were applied to 2-year-old well-grown seedlings under drought conditions (30% field moisture capacity). Stomatal conductance, transpiration rate and net photosynthetic rate were measured by a LI-6400 photosynthesis system, while water use efficiency was calculated from net photosynthesis rate and transpiration rate. The results revealed that as the amount of urea applied was raised, stomatal conductance, transpiration rate and net photosynthetic rate decreased significantly, and thus water use efficiency significantly increased. It is therefore concluded that the application of nitrogenous fertilizer regulated physiological parameters by reducing stomata conductance to improve water use efficiency. In addition, among the four tree species, U. pumila had the maximum value of water use efficiency under the same drought condition. The outcome of this study provides a guided option for forest management in arid and semi-arid areas of northwest China.

  5. Evaporation, transpiration, and ecosystem water use efficiency in a multi-annual sugarcane production system in Hawai'i, USA

    NASA Astrophysics Data System (ADS)

    Anderson, R. G.; Tirado-corbala, R.; Wang, D.; Ayars, J. E.

    2013-12-01

    Food and biofuel production will require practices that increase water use efficiency in order to have future sustainability in a water-constrained environment. One possible practice is the use of food and energy crops with multi-annual growing periods, which could reduce bare soil evaporation. We integrated field water budgets, micrometeorology, and plant sampling to observe plant growth and evapotranspiration (ET) in two sugarcane (Saccharum officinarum L.) fields in Hawai'i, USA in contrasting environments with unusually long (18-24 month) growing periods. We partitioned observed ET into evaporation and transpiration using a flux partitioning model and calculated ecosystem water use efficiency (EWUE=Net Ecosystem Productivity/ET) and harvest WUE (HWUE=Aboveground Net Ecosystem Productivity/ET) to assess sugarcane water use efficiency. After the start of the mid-period, our higher elevation, less windy field ('Lee') had a slightly higher mean EWUE (31.5 kg C ha-1 mm-1) than our lower elevation, windier ('Windy') field (mean EWUE of 30.7 kg C ha-1 mm-1). HWUE was also very high (HWUE >27 kg C ha-1 mm-1) in both fields due to aboveground biomass composing >87% of total biomass. Transpiration, as a fraction of total ET, increased rapidly with canopy cover in both fields; during the mid-period, transpiration was an average of 84% of total ET in Windy and 80% in Lee, with Lee showing greater variation than Windy. As expected, daily EWUE increased with canopy cover during the initial growing stages; more significantly, EWUE showed no substantial decrease during the 2nd year with an aging crop. The results illustrate the potential for longer-rotation crop cycles for increasing water use efficiency, particularly in tropical regions.

  6. Yield and gas exchange ability of sweetpotato plants cultured in a hydroponic system

    NASA Astrophysics Data System (ADS)

    Kitaya, Y.; Hirai, H.; Saiful Islam, A. F. M.; Yamamoto, M.

    Life support of crews in space is greatly dependent on the amounts of food atmospheric O 2 and clean water produced by plants Therefore the space farming systems with scheduling of crop production obtaining high yields with a rapid turnover rate converting atmospheric CO 2 to O 2 and purifying water should be established with employing suitable plant species and varieties and precisely controlling environmental variables around plants grown at a high density in a limited space In this study three sweetpotato varieties were cultured in a newly developed hydroponic system and the yield the photosynthetic rate and the transpiration rate were compared on the earth as a fundamental study for establishing the space farming systems The varieties were Elegant summer Koukei 14 and Beniazuma The hydroponic system mainly consisted of water channels and rockwool boards A growing space for roots was made between the rockwool board and nutrient solution in the water channel Storage roots were developed on the lower surface of the rockwool plates Fresh weights of the storage roots were 1 6 1 2 and 0 6 kg plant for Koukei 14 Elegant summer and Beniazuma respectively grown for five months from June to October under the sun light in Osaka Japan Koukei 14 and Elegant summer produced greater total phytomass than Beniazuma There were positive correlations among the total phytomass the net photosynthetic rate and the transpiration rate Young stems and leaves as well as storage roots of Elegant summer are edible Therefore Elegant-summer

  7. Rapid plant species loss at high rates and at low frequency of N addition in temperate steppe.

    PubMed

    Zhang, Yunhai; Lü, Xiaotao; Isbell, Forest; Stevens, Carly; Han, Xu; He, Nianpeng; Zhang, Guangming; Yu, Qiang; Huang, Jianhui; Han, Xingguo

    2014-11-01

    Humans are both intentionally (fertilization) and unintentionally (atmospheric nutrient deposition) adding nutrients worldwide. Increasing availability of biologically reactive nitrogen (N) is one of the major drivers of plant species loss. It remains unclear, however, whether plant diversity will be equally reduced by inputs of reactive N coming from either small and frequent N deposition events or large and infrequent N fertilization events. By independently manipulating the rate and frequency of reactive N inputs, our study teases apart these potentially contrasting effects. Plant species richness decreased more quickly at high rates and at low frequency of N addition, which suggests that previous fertilization studies have likely over-estimated the effects of N deposition on plant species loss. N-induced species loss resulted from both acidification and ammonium toxicity. Further study of small and frequent N additions will be necessary to project future rates of plant species loss under increasing aerial N deposition. PMID:24753127

  8. Characteristics of microbial volatile organic compound flux rates from soil and plant litter

    NASA Astrophysics Data System (ADS)

    Gray, C. M.; Fierer, N.

    2013-12-01

    Our knowledge of microbial production and consumption of volatile organic compounds (VOCs) from soil and litter, as well as which microorganisms are involved, is relatively limited compared to what we know about VOC emissions from terrestrial plants. With climate change expecting to alter plant community composition, nitrogen (N) deposition rates, mean annual temperatures, precipitation patterns, and atmospheric VOC concentrations, it is unknown how microbial production and consumption of VOCs from litter and soil will respond. We have spent the last 5 years quantifying VOC flux rates in decaying plant litter, mineral soils and from a subalpine field site using a proton transfer reaction mass spectrometer (PTR-MS). Microbial production, relative to abiotic sources, accounted for 78% to 99% of the total VOC emissions from decomposing litter, highlighting the importance of microbial metabolisms in these systems. Litter chemistry correlated with the types of VOCs emitted, of which, methanol was emitted at the highest rates from all studies. The net emissions of carbon as VOCs was found to be up to 88% of that emitted as CO2 suggesting that VOCs likely represent an important component of the carbon cycle in many terrestrial systems. Nitrogen additions drastically reduced VOC emissions from litter to near zero, though it is still not understood whether this was due to an increase in consumption or a decrease in production. In the field, the root system contributed to 53% of the carbon that was emitted as VOCs from the soil with increasing air temperatures correlating to an increase in VOC flux rates from the soil system. Finally, we are currently utilizing next generation sequencing techniques (Illumina MiSeq) along with varying concentrations of isoprene, the third most abundant VOC in the atmosphere behind methane and methanol, above soils in a laboratory incubation to determine consumption rates and the microorganisms (bacteria, archaea and fungi) associated with the consumption of isoprene in soils. To our knowledge, this is a novel technique for identifying microorganisms associated with consumption without the use of culturing or isotopic labeling. Together, these series of studies are moving us toward a predictive understanding of VOC fluxes and microbial ecology in soil and litter.

  9. The Role of Detailed Land Cover Data on Modeling Transpiration in a Managed Forested Landscape

    NASA Astrophysics Data System (ADS)

    Mackay, D. S.; Ahl, D. E.; Ewers, B. E.; Samanta, S.; Burrows, S. N.; Gower, S. T.

    2001-05-01

    Remotely sensed vegetation data is a primary data source for land surface hydrology models. For example, leaf area index (LAI), is widely seen as a key variable in modeling water, carbon, and energy at the land surface. On the other hand, species-specific knowledge of land cover types is often considered less important at the landscape scale. We hypothesize that this assumption might not hold in a managed forest with changing patterns of forest cover types. We tested the significance of site-specific remotely sensed land cover classification for making regional estimates of evapotranspiration in northern Wisconsin, USA. We developed a site-specific land cover classification at 15m resolution using NASA's Airborne Terrestrial Applications Sensor (ATLAS). A field campaign consisted of detailed ground control for image geometry correction and registration, and 324 permanent plots for vegetation cover types and leaf area index and other ecosystem parameters. We then identified four major forest cover types (forested wetland, aspen/fir, northern hardwoods, and conifers) that represent 85 percent of the 100 km2 landscape around our site. In representative stands for each cover type we made continuous sap flux and micrometeorological measurements, from which stand-type parameter sets were developed for use in a regional hydrologic model. Simulated transpiration flux with this detailed model was then compared with a less detailed parameterization based on limited cover type information and BIOME-BGC type parameter values. Disparity between the more aggregated parameter approach and the detailed approach was due to nonlinear mixing of different forest stomatal physiology. For instance, the aspen/fir stands transpire at a rate of 2 mm/day, but northern hardwoods transpire at 1 mm/day, for the same LAI. The results indicate that land cover classification may be as critical as LAI for land surface modeling at large scales. The detailed information could, for example, be combined with coarser global data sets by using site-specific sampling with high-resolution remote sensing data.

  10. Elevated Atmospheric CO2 Affects the Chemical Quality of Brassica Plants and the Growth Rate of the Specialist, Plutella

    E-print Network

    Reddy, Gadi VP

    . Lennox and Rinda), and oilseed rape, Brassica rapa subsp. oleifera (cv. Valo and Tuli), plants were grownElevated Atmospheric CO2 Affects the Chemical Quality of Brassica Plants and the Growth Rate, University of Kuopio, P.O. Box 1627, FIN-70211 Kuopio, Finland Cabbage, Brassica oleracea subsp. capitata (cv

  11. Shock/shock interference on a transpiration cooled hemispherical model

    NASA Technical Reports Server (NTRS)

    Nowak, Robert J.; Wieting, Allan R.; Holden, Michael S.

    1990-01-01

    Experimental results are presented which show the effectiveness of transpiration cooling in reducing the peak heat flux caused by an impinging shock on a bow shock of a hemispherical model. The 12-inch diameter hemispherical transpiration model with helium coolant was tested in the Calspan 48-inch Hypersonic Shock Tunnel at nominal Mach 12.1 and freestream unit Reynolds number of 0.33 x 10 to the 6th/ft. An incident shock wave, generated by a blunt flat-plate shock generator inclined at 10 deg to the freestream, intersected the bow shock of the model to produce shock/shock interference. The stagnation heat flux without coolant or shock/shock interference was about 1.6 times a smooth surface laminar prediction due to effective roughness of the coolant ejection slots. A coolant mass flux 31 percent of the freestream mass flux reduced the stagnation heat flux to zero without shock/shock interference. However, for the same coolant mass flux and with shock/shock interference the peak heat flux was only reduced 8.3 percent, even though the total integrated heat load was reduced.

  12. Cyclic variations in nitrogen uptake rate of soybean plants: effects of external nitrate concentration

    NASA Technical Reports Server (NTRS)

    Tolley-Henry, L.; Raper, C. D. Jr; Granato, T. C.; Raper CD, J. r. (Principal Investigator)

    1988-01-01

    Net uptake of NO3- by non-nodulated soybean plants [Glycine max (L.) Merr. cv. Ransom] growing in flowing hydroponic cultures containing 0.5, 1.0 and 10.0 mol m-3 NO3- was measured daily during a 24-d period of vegetative development to determine if amplitude of maximum and minimum rates of net NO3- uptake are responsive to external concentrations of NO3-. Removal of NO3- from the replenished solutions during each 24-h period was determined by ion chromatography. Neither dry matter accumulation nor the periodicity of oscillations in net uptake rate was altered by the external NO3- concentrations. The maxima of the oscillations in net uptake rate, however, increased nearly 3-fold in response to external NO3- concentrations. The maxima and minima, respectively, changed from 4.0 and 0.6 mmol NO3- per gram root dry weight per day at an external solution level of 0.5 mol m-3 NO3- to 15.2 and -2.7 mmol NO3- per gram root dry weight per day at an external solution level of 10.0 mol m-3 NO3-. The negative values for minimum net uptake rate from 10.0 mol m-3 NO3- solutions show that net efflux was occurring and indicate that the magnitude of the efflux component of net uptake was responsive to external concentration of NO3-.

  13. Improving power plant efficiency and safety through better knowledge of flow-rates: The EDF approach

    SciTech Connect

    Piguet, M.

    1998-07-01

    The flow-rate is an important parameter in power plant operation for both performance and safety purposes. As an example, in nuclear and fossil power plants, the uncertainty concerning thermal and electrical powers is directly connected to the uncertainty of the feedwater flow. In real conditions, the flow-rate is often incorrectly determined due to various phenomena among which are incorrect installation conditions, wrong calibrations and drift, erosion or fouling of the flowmeters. These phenomena may lead to systematic errors which can represent several percents of the measured value and which can induce a critical loss of profit. This paper presents the strategy and means of EDF's R and D Division to improve actual accuracy of flowmeters used in power plants. The experimental approach has always been an efficient way to investigate and make a diagnosis of real situations. The EVEREST loop is a dedicated rig within EDF for the study of liquid flow metering problems. It enables to calibrate industrial flowmeters, evaluate prototypes and study the specific installation conditions of flowmeters. It is often noticed that flowmeters do not respect the standards in terms of straight lengths upstream from the meter. A practical example (1,300 MW unit feedwater flow) illustrates the possibility the EVEREST loop offers to reproduce the geometry of the hydraulic circuit and flow conditions. The impact of the actual installation conditions on the flowmeter accuracy can be thus determined and the flowmeter can be possibly recalibrated in order to reduce or correct a systematic bias. The EDF tool is presented with examples of accuracy and experimental and numerical modeling.

  14. REGULAR ARTICLE Hyperaccumulation of nickel by Alyssum corsicum

    E-print Network

    Sparks, Donald L.

    and plant transpiration rate. The most soluble compounds had the highest Ni uptake, with the exception of Ni plant uptake and transpiration rate. In ser- pentine soils and insoluble NiO plant transpiration rate and the plant transpiration rate. Keywords Ni minerals . Alyssum . Hyperaccumulators . Ni solubility

  15. Physiological tradeoffs in the parameterization of a model of canopy transpiration

    Microsoft Academic Search

    D. S. Mackay; D. E. Ahl; B. E. Ewers; S. Samanta; S. T. Gower; S. N. Burrows

    2003-01-01

    We examined physiological parameter tradeoffs in modeling stomatal control of transpiration from a number of forest species. Measurements of sapflux, micrometeorology, and leaf area index were made in stands representing 85% of the forest ecosystems around the WLEF eddy flux tower in northern Wisconsin. A Jarvis-based canopy conductance model was used to simulate canopy transpiration (EC) for five tree species

  16. Leaf transpiration efficiency of sweet corn varieties from three eras of breeding

    Technology Transfer Automated Retrieval System (TEKTRAN)

    When measured under midday field conditions, modern varieties of corn often have sub-stomatal concentrations of carbon dioxide in excess of those required to saturate photosynthesis. This results in lower leaf transpiration efficiency, the ratio of photosynthesis to transpiration, than potentially ...

  17. Mathematical modeling and thermal performance analysis of unglazed transpired solar collectors

    Microsoft Academic Search

    M. Augustus Leon; S. Kumar

    2007-01-01

    Unglazed transpired collectors or UTC (also known as perforated collectors) are a relatively new development in solar collector technology, introduced in the early nineties for ventilation air heating. These collectors are used in several large buildings in Canada, USA and Europe, effecting considerable savings in energy and heating costs. Transpired collectors are a potential replacement for glazed flat plate collectors.

  18. A kinetic model for transpiration of fresh produce in a controlled atmosphere

    Microsoft Academic Search

    Jun Soo Kang; Dong Sun Lee

    1998-01-01

    A simple transpiration model based on heat and mass balances between produce and storage atmosphere was developed and tested experimentally to predict moisture loss of fresh produce in normal air and in a controlled atmosphere. The transpiring water transfer was coupled to heat transfer at steady state. Sum of heat energies transferred through natural convection from ambient air and generated

  19. Environmental and biological controls of urban tree transpiration in the Upper Midwest

    Microsoft Academic Search

    E. B. Peters; J. McFadden; R. Montgomery

    2009-01-01

    Urban trees provide a variety of ecosystem services to urban and suburban areas, including carbon uptake, climate amelioration, energy reduction, and stormwater management. Tree transpiration, in particular, modifies urban water budgets by providing an alternative pathway for water after rain events. The relative importance of environmental and biological controls on transpiration are poorly understood in urban areas, yet these controls

  20. Helianthus Nighttime Conductance and Transpiration Respond to Soil Water But Not Nutrient Availability1[W][OA

    PubMed Central

    Howard, Ava R.; Donovan, Lisa A.

    2007-01-01

    We investigated the response of Helianthus species nighttime conductance (gnight) and transpiration (Enight) to soil nutrient and water limitations in nine greenhouse studies. The studies primarily used wild Helianthus annuus, but also included a commercial and early domesticate of H. annuus and three additional wild species (Helianthus petiolaris Nutt., Helianthus deserticola Heiser, and Helianthus anomalus Blake). Well-watered plants of all species showed substantial gnight (0.023–0.225 mol m?2 s?1) and Enight (0.29–2.46 mmol m?2 s?1) measured as instantaneous gas exchange. Based on the potential for transpiration to increase mass flow of mobile nutrients to roots, we hypothesized that gnight and Enight would increase under limiting soil nutrients but found no evidence of responses in all six studies testing this. Based on known daytime responses to water limitation, we hypothesized that gnight and Enight would decrease when soil water availability was limited, and results from all four studies testing this supported our hypothesis. We also established that stomatal conductance at night was on average 5 times greater than cuticular conductance. Additionally, gnight and Enight varied nocturnally and across plant reproductive stages while remaining relatively constant as leaves aged. Our results further the ability to predict conditions under which nighttime water loss will be biologically significant and demonstrate that for Helianthus, gnight can be regulated. PMID:17142487

  1. Effects of pheromone and plant volatile release rates and ratios on trapping Anoplophora glabripennis (Coleoptera: Cerambycidae) in China.

    PubMed

    Meng, P S; Trotter, R T; Keena, M A; Baker, T C; Yan, S; Schwartzberg, E G; Hoover, K

    2014-10-01

    Native to China and Korea, the Asian longhorned beetle, Anoplophora glabripennis (Motschulsky) (Coleoptera: Cerambycidae), is a polyphagous wood-boring pest for which a trapping system would greatly benefit eradication and management programs in both the introduced and native ranges. Over two field seasons, a total of 160 flight intercept panel traps were deployed in Harbin, China, which trapped a total of 65 beetles. In 2012, traps using lures with a 1:1 ratio of the male-produced pheromone components (4-(n-heptyloxy)butanal and 4-(n-heptyloxy)butan-1-ol) designed to release at a rate of 1 or 4 milligram per day per component in conjunction with the plant volatiles (-)-linalool, trans-caryophyllene, and (Z)-3-hexen-1-ol caught significantly more A. glabripennis females than other pheromone release rates, other pheromone ratios, plant volatiles only, and no lure controls. Males were caught primarily in traps baited with plant volatiles only. In 2013, 10× higher release rates of these plant volatiles were tested, and linalool oxide was evaluated as a fourth plant volatile in combination with a 1:1 ratio of the male-produced pheromone components emitted at a rate of 2 milligram per day per component. Significantly more females were trapped using the pheromone with the 10-fold higher three or four plant volatile release rates compared with the plant volatiles only, low four plant volatile + pheromone, and control. Our findings show that the male-produced pheromone in combination with plant volatiles can be used to detect A. glabripennis. Results also indicate that emitters should be monitored during the field season, as release rates fluctuate with environmental conditions and can be strongly influenced by formulation additives. PMID:25259696

  2. Responses of transpiration and photosynthesis to reversible changes in photosynthetic foliage area in western red cedar (Thuja plicata) seedlings.

    PubMed

    Pepin, S; Livingston, N J; Whitehead, D

    2002-04-01

    Experiments were conducted on 1-year-old western red cedar (Thuja plicata Donn.) seedlings to determine the response of illuminated foliage to reversible changes in total photosynthetic foliage area (L(A)). Reductions in L(A) were brought about by either shading the lower foliage or by reducing the ambient CO2 concentration (c(a)) of the air surrounding the lower part of the seedling. In the latter case, the vapor pressure was also changed so that transpiration rates (E) could be manipulated independently of photosynthetic rates (A). We hypothesized that following such treatments, short-term compensatory changes would occur in stomatal conductance (g(s)) and A of the remaining foliage. These changes would occur in response to hydraulic signals generated by changes in the water potential gradient rather than changes in the distribution of sources and sinks of carbon within the seedling. When a portion of the foliage was shaded, there was an immediate reduction in whole-seedling E and a concomitant increase in g(s), A and E in the remaining illuminated foliage. However, the intercellular CO2 concentration did not change. These compensatory effects were fully reversed after the shade was removed. When the lower foliage A was reduced to < 0 micromol m-2 s-1, by shading or lowering c(a), and E was either unchanged or increased (by adjusting the vapor pressure deficit), there was no significant increase in g(s) and A in the remaining foliage. We conclude that compensatory responses in illuminated foliage occur only when reductions in L(A) are accompanied by a reduction in whole-plant E. The relationship between the reduction in whole-seedling E and the increase in A is highly linear (r2 = 0.68) and confirms our hypothesis of the strong regulation of g(s) by hydraulic signals generated within the seedling. We suggest that the mechanism of the compensatory effects is a combination of both increased CO2 supply, resulting from increased g(s), and a response of the rate of carboxylation, possibly related to the activity of Rubisco. PMID:11960761

  3. Plant diversity does not buffer drought effects on early-stage litter mass loss rates and microbial properties.

    PubMed

    Vogel, Anja; Eisenhauer, Nico; Weigelt, Alexandra; Scherer-Lorenzen, Michael

    2013-09-01

    Human activities are decreasing biodiversity and changing the climate worldwide. Both global change drivers have been shown to affect ecosystem functioning, but they may also act in concert in a non-additive way. We studied early-stage litter mass loss rates and soil microbial properties (basal respiration and microbial biomass) during the summer season in response to plant species richness and summer drought in a large grassland biodiversity experiment, the Jena Experiment, Germany. In line with our expectations, decreasing plant diversity and summer drought decreased litter mass loss rates and soil microbial properties. In contrast to our hypotheses, however, this was only true for mass loss of standard litter (wheat straw) used in all plots, and not for plant community-specific litter mass loss. We found no interactive effects between global change drivers, that is, drought reduced litter mass loss rates and soil microbial properties irrespective of plant diversity. High mass loss rates of plant community-specific litter and low responsiveness to drought relative to the standard litter indicate that soil microbial communities were adapted to decomposing community-specific plant litter material including lower susceptibility to dry conditions during summer months. Moreover, higher microbial enzymatic diversity at high plant diversity may have caused elevated mass loss of standard litter. Our results indicate that plant diversity loss and summer drought independently impede soil processes. However, soil decomposer communities may be highly adapted to decomposing plant community-specific litter material, even in situations of environmental stress. Results of standard litter mass loss moreover suggest that decomposer communities under diverse plant communities are able to cope with a greater variety of plant inputs possibly making them less responsive to biotic changes. PMID:23606531

  4. Differentiating transpiration from evaporation in seasonal agricultural wetlands and the link to advective fluxes in the root zone

    USGS Publications Warehouse

    Bachand, P.A.M.; S. Bachand; Fleck, Jacob A.; Anderson, Frank E.; Windham-Myers, Lisamarie

    2014-01-01

    The current state of science and engineering related to analyzing wetlands overlooks the importance of transpiration and risks data misinterpretation. In response, we developed hydrologic and mass budgets for agricultural wetlands using electrical conductivity (EC) as a natural conservative tracer. We developed simple differential equations that quantify evaporation and transpiration rates using flowrates and tracer concentrations atwetland inflows and outflows. We used two ideal reactormodel solutions, a continuous flowstirred tank reactor (CFSTR) and a plug flow reactor (PFR), to bracket real non-ideal systems. From those models, estimated transpiration ranged from 55% (CFSTR) to 74% (PFR) of total evapotranspiration (ET) rates, consistent with published values using standard methods and direct measurements. The PFR model more appropriately represents these nonideal agricultural wetlands in which check ponds are in series. Using a fluxmodel, we also developed an equation delineating the root zone depth at which diffusive dominated fluxes transition to advective dominated fluxes. This relationship is similar to the Peclet number that identifies the dominance of advective or diffusive fluxes in surface and groundwater transport. Using diffusion coefficients for inorganic mercury (Hg) and methylmercury (MeHg) we calculated that during high ET periods typical of summer, advective fluxes dominate root zone transport except in the top millimeters below the sediment–water interface. The transition depth has diel and seasonal trends, tracking those of ET. Neglecting this pathway has profound implications: misallocating loads along different hydrologic pathways; misinterpreting seasonal and diel water quality trends; confounding Fick's First Law calculations when determining diffusion fluxes using pore water concentration data; and misinterpreting biogeochemicalmechanisms affecting dissolved constituent cycling in the root zone. In addition,our understanding of internal root zone cycling of Hg and other dissolved constituents, benthic fluxes, and biological irrigation may be greatly affected.

  5. Evaporation and transpiration from forests in Central Europe - relevance of patch-level studies for spatial scaling

    NASA Astrophysics Data System (ADS)

    Köstner, B.

    Spatial scaling from patch to the landscape level requires knowledge on the effects of vegetation structure on maximum surface conductances and evaporation rates. The following paper summarizes results on atmospheric, edaphic, and structural controls on forest evaporation and transpiration observed in stands of Norway spruce (Picea abies), Scots pine (Pinus sylvestris) and European beech (Fagus sylvatica). Forest canopy transpiration (Ec) was determined by tree sapflow measurements scaled to the stand level. Estimates of understory transpiration and forest floor evaporation were derived from lysimeter and chamber measurements. Strong reduction of Ec due to soil drought was only observed at a Scots pine stand when soil water content dropped below 16% v/v. Although relative responses of Ec on atmospheric conditions were similar, daily maximum rates of could differ more than 100% between forest patches of different structure (1.5-3.0mmd-1 and 2.6-6.4mmd-1 for spruce and beech, respectively). A significant decrease of Ecmax per leaf area index with increasing stand age was found for monocultures of Norway spruce, whereas no pronounced changes in were observed for beech stands. It is concluded that structural effects on Ecmax can be specified and must be considered for spatial scaling from forest stands to landscapes. Hereby, in conjunction with LAI, age-related structural parameters are important for Norway spruce stands. Although compensating effects of tree canopy layers and understory on total evaporation of forests were observed, more information is needed to quantify structure-function relationships in forests of heterogenous structure.

  6. Estimates of deep drainage rates at the U.S. Department of Energy Pantex Plant, Amarillo, Texas

    SciTech Connect

    Fayer, M.J.; Richmond, M.C.; Wigmosta, M.S. [Pacific Northwest National Lab., Richland, WA (United States); Kelley, M.E. [Battelle Environmental Restoration Dept., Columbus, OH (United States)

    1998-04-01

    In FY 1996, the Pacific Northwest National Laboratory (PNNL) provided technical assistance to Battelle Columbus Operations (BCO) in their ongoing assessment of contaminant migration at the Pantex Plant in Amarillo, Texas. The objective of this report is to calculate deep drainage rates at the Pantex Plant. These deep drainage rates may eventually be used to predict contaminant loading to the underlying unconfined aquifer for the Pantex Plant Baseline Risk Assessment. These rates will also be used to support analyses of remedial activities involving surface alterations or the subsurface injection withdrawal of liquids or gases. The scope of this report is to estimate deep drainage rates for the major surface features at the Pantex Plant, including ditches and playas, natural grassland, dryland crop rotation, unvegetated soil, and graveled surfaces. Areas such as Pantex Lake that are outside the main plant boundaries were not included in the analysis. All estimates were derived using existing data or best estimates; no new data were collected. The modeling framework used to estimate the rates is described to enable future correlations, improvements, and enhancements. The scope of this report includes only data gathered during FY 1996. However, a current review of the data gathered on weather, soil, plants, and other information in the time period since did not reveal anything that would significantly alter the results presented in this report.

  7. An improved heat pulse method to measure low and reverse rates of sap flow in woody plants

    Microsoft Academic Search

    STEPHEN S. O. BURGESS; MARK A. ADAMS; NEIL C. TURNER; CRAIG R. BEVERLY; CHIN K. ONG; AHMED A. H. KHAN; TIM M. BLEBY

    Summary The compensation heat pulse method (CHPM) is of limited value for measuring low rates of sap flow in woody plants. Recent application of the CHPM to woody roots has further illustrated some of the constraints of this technique. Here we present an improved heat pulse method, termed the heat ratio method (HRM), to measure low and reverse rates of

  8. Effect of gender on sap-flux-scaled transpiration in a dominant riparian tree species: Box elder (Acer negundo)

    E-print Network

    Ehleringer, Jim

    Effect of gender on sap-flux-scaled transpiration in a dominant riparian tree species: Box elder transpiration flux from dominant riparian vegetation away from streamsides (estimated from scaled sap flux contributed 31 and 46% respectively of the estimated 8.0 mm dÃ?1 transpiration flux from dominant riparian

  9. Ptant, Cett and Environment (1997) 20,1242-1252 Control of transpiration from the upper canopy of a tropicai

    E-print Network

    Holbrook, N. Michele

    Ptant, Cett and Environment (1997) 20,1242-1252 Control of transpiration from the upper canopy con- ductance (g^), transpiration [E) and microenvironmental variables were used to characterize control of crown transpiration in four tree species growing in a moist, low- land tropical forest. Access

  10. Controls on transpiration in a semiarid riparian cottonwood forest Rico M. Gazal a,*, Russell L. Scott b

    E-print Network

    Williams, David G.

    Controls on transpiration in a semiarid riparian cottonwood forest Rico M. Gazal a,*, Russell L transpiration by this vegetation type responds to environmental forcing is important for determining the water balance dynamics of riparian ecosystems threatened by groundwater depletion. Transpiration was measured

  11. A stomatal optimization theory to describe the effects of atmospheric CO2 on leaf photosynthesis and transpiration

    E-print Network

    Katul, Gabriel

    and transpiration Gabriel Katul1,2, Stefano Manzoni1,2, Sari Palmroth1,* and Ram Oren1 1 Nicholas School conductance and transpiration due to increases in atmospheric CO2. The consequences of these reductions transpiration have a long history ­ beginning perhaps with the seminal experiments of Edme Mariotte around 1660

  12. Transpiration efficiency over an annual cycle, leaf gas exchange and wood carbon isotope ratio of three tropical tree species

    E-print Network

    Bermingham, Eldredge

    Transpiration efficiency over an annual cycle, leaf gas exchange and wood carbon isotope ratio; published online August 6, 2009 Summary Variation in transpiration efficiency (TE) and its relationship. Cumulative transpiration was determined by repeatedly weighing the pots with a pallet truck scale. Dry matter

  13. Agricultural and Forest Meteorology 105 (2000) 257270 Transpiration of cottonwood/willow forest estimated from sap flux

    E-print Network

    Williams, David G.

    Agricultural and Forest Meteorology 105 (2000) 257­270 Transpiration of cottonwood/willow forest to estimate transpiration in 12 such forest patches along a perennially flowing reach of the San Pedro River in southeastern Arizona, USA during five periods from April to October 1997. Transpiration per unit sapwood area

  14. The effect of transpiration on coupled heat and mass transfer in mixed convection over a vertical plate embedded in a saturated porous medium

    SciTech Connect

    Yih, K.A. [Air Forces Inst. of Aeronautical Technology, Kaoshiuang (Taiwan, Province of China). Dept. of General Course] [Air Forces Inst. of Aeronautical Technology, Kaoshiuang (Taiwan, Province of China). Dept. of General Course

    1997-03-01

    Effect of transpiration velocity on the heat and mass transfer characteristics of mixed convection about a permeable vertical plate embedded in a saturated porous medium under the coupled effects of thermal and mass diffusion is numerically analyzed. The plate is maintained at a uniform temperature and species concentration with constant transpiration velocity. The transformed governing equations are solved by Keller box method. Numerical results for the local Nusselt number and local Sherwood number are presented. In general, it has been found for thermally assisted flow that the local surface heat and mass transfer rates increase owing to suction of fluid. This trend reversed for blowing of fluid. It is apparent that the Lewis number has a pronounced effect on the local Sherwood number than it does on the local Nusselt number. Increasing the Lewis number decreases (increases) the local heat (mass) transfer rate.

  15. Estimation of the rate of increase in nitrogen dioxide concentrations from power plant stacks using an imaging-DOAS.

    PubMed

    Lee, Hanlim; Kim, Young J; Lee, Chulkyu

    2009-05-01

    The emission of nitrogen compounds from power plants accounts for a significant proportion of the total emissions of nitrogen to the atmosphere. This study seeks to understand the nature of chemical reactions in the atmosphere involving nitrogen, which is important in undertaking quantitative assessments of the contribution of such reactions to local and regional air pollution. The slant column density (SCD) of power-plant-generated NO(2) was derived using imaging differential optical absorption spectroscopy (I-DOAS) with scattered sunlight as a light source. The vertical structure of NO(2) SCD from power plant stacks was simultaneously probed using a pushbroom sensor. Measured SCDs were converted to mixing ratios in calculating the rate of NO(2) increase at the center of the plume. This study presents quantitative measurements of the rate of NO(2) increase in a rising plume. An understanding of the rate of NO(2) increase is important because SO(2) and NO(x) compete for the same oxidizing radicals, and the amount of NO(x) is related to the rates of SO(2) oxidation and sulfate formation. This study is the first to directly obtain the rate of NO(2) increase in power plant plumes using the I-DOAS technique. NO(2) increase rates of 60 and 70 ppb s(-1) were observed at distances of about 45 m from the two stacks of the Pyeongtaek Power Plant, northwest South Korea. PMID:18535919

  16. Coupled soil respiration and transpiration dynamics from tree-scale to catchment scale in dry Rocky Mountain pine forests and the role of snowpack

    NASA Astrophysics Data System (ADS)

    Berryman, E.; Barnard, H. R.; Brooks, P. D.; Adams, H.; Burns, M. A.; Wilson, W.; Stielstra, C. M.

    2013-12-01

    A current ecohydrological challenge is quantifying the exact nature of carbon (C) and water couplings across landscapes. An emerging framework of understanding places plant physiological processes as a central control over soil respiration, the largest source of CO2 to the atmosphere. In dry montane forests, spatial and temporal variability in forest physiological processes are governed by hydrological patterns. Critical feedbacks involving respiration, moisture supply and tree physiology are poorly understood and must be quantified at the landscape level to better predict carbon cycle implications of regional drought under future climate change. We present data from an experiment designed to capture landscape variability in key coupled hydrological and C processes in forests of Colorado's Front Range. Sites encompass three catchments within the Boulder Creek watershed, range from 1480 m to 3021 m above sea level and are co-located with the DOE Niwot Ridge Ameriflux site and the Boulder Creek Critical Zone Observatory. Key hydrological measurements (soil moisture, transpiration) are coupled with soil respiration measurements within each catchment at different landscape positions. This three-dimensional study design also allows for the examination of the role of water subsidies from uplands to lowlands in controlling respiration. Initial findings from 2012 reveal a moisture threshold response of the sensitivity of soil respiration to temperature. This threshold may derive from tree physiological responses to variation in moisture availability, which in turn is controlled by the persistence of snowpack. Using data collected in 2013, first, we determine whether respiration moisture thresholds represent triggers for transpiration at the individual tree level. Next, using stable isotope ratios of soil respiration and xylem and soil water, we compare the depths of respiration to depths of water uptake to assign tree vs. understory sources of respiration. This will help determine whether tree root-zone respiration exhibits a similar moisture threshold. Lastly, we examine whether moisture thresholds to temperature sensitivity are consistent across a range of snowpack persistence. Findings are compared to data collected from sites in Arizona and New Mexico to better establish the role of winter precipitation in governing growing season respiration rates. The outcome of this study will contribute to a better understanding of linkages among water, tree physiology, and soil respiration with the ultimate goal of scaling plot-level respiration fluxes to entire catchments.

  17. The influence of nitrogen rate and source on plant and soil properties

    E-print Network

    Fisher, Flake Leroy

    1959-01-01

    , and and are the annual rate of nitrogen in pounds p er a c r e app lied as ammonium nitrate and anhydrous ammonia, r e sp e c t iv e ly . P red ic ted maximum y ields com pared favorab ly with the actual m aximum y ie lds o f 1 9 , 9 9 0 and 15, 850 pounds... o f d ry fo rage p er a c r e per y ea r . Ammonium nitrate p rodu ced fo ra g e o f a higher su ccu len cy than did anhydrous ammonia, while in crea s ing the leve l of s o i l nitrogen f r om either sou r ce in crea sed plant...

  18. A prototype photovoltaic/thermal system integrated with transpired collector

    SciTech Connect

    Athienitis, Andreas K.; Bambara, James; O'Neill, Brendan; Faille, Jonathan [Dept. of Building, Civil and Environmental Engineering, Concordia University, 1455 Maisonneuve W., Montreal, Quebec (Canada)

    2011-01-15

    Building-integrated photovoltaic/thermal (BIPV/T) systems may be utilized to produce useful heat while simultaneously generating electricity from the same building envelope surface. A well known highly efficient collector is the open-loop unglazed transpired collector (UTC) which consists of dark porous cladding through which outdoor air is drawn and heated by absorbed solar radiation. Commercially available photovoltaic systems typically produce electricity with efficiencies up to about 18%. Thus, it is beneficial to obtain much of the normally wasted heat from the systems, possibly by combining UTC with photovoltaics. Combination of BIPV/T and UTC systems for building facades is considered in this paper - specifically, the design of a prototype facade-integrated photovoltaic/thermal system with transpired collector (BIPV/T). A full scale prototype is constructed with 70% of UTC area covered with PV modules specially designed to enhance heat recovery and compared to a UTC of the same area under outdoor sunny conditions with low wind. The orientation of the corrugations in the UTC is horizontal and the black-framed modules are attached so as to facilitate flow into the UTC plenum. While the overall combined thermal efficiency of the UTC is higher than that of the BIPV/T system, the value of the generated energy - assuming that electricity is at least four times more valuable than heat - is between 7% and 17% higher. Also, the electricity is always useful while the heat is usually utilized only in the heating season. The BIPV/T concept is applied to a full scale office building demonstration project in Montreal, Canada. The ratio of photovoltaic area coverage of the UTC may be selected based on the fresh air heating needs of the building, the value of the electricity generated and the available building surfaces. (author)

  19. Plant response of onion cultivars developed from greenhouse-grown transplants to plant density and fertilizer rate

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Onions (Allium cepa L.) can be established from seed or transplants. The latter planting material can be dormant or actively growing when transplanted to the field. Onion transplants can be produced in a greenhouse, but there are gaps in the knowledge of the cultural requirements for these plants ...

  20. Fog reduces transpiration in tree species of the Canarian relict heath-laurel cloud forest (Garajonay National Park, Spain).

    PubMed

    Ritter, Axel; Regalado, Carlos M; Aschan, Guido

    2009-04-01

    The ecophysiologic role of fog in the evergreen heath-laurel 'laurisilva' cloud forests of the Canary Islands has not been unequivocally demonstrated, although it is generally assumed that fog water is important for the survival and the distribution of this relict paleoecosystem of the North Atlantic Macaronesian archipelagos. To determine the role of fog in this ecosystem, we combined direct transpiration measurements of heath-laurel tree species, obtained with Granier's heat dissipation probes, with micrometeorological and artificial fog collection measurements carried out in a 43.7-ha watershed located in the Garajonay National Park (La Gomera, Canary Islands, Spain) over a 10-month period. Median ambient temperature spanned from 7 to 15 degrees C under foggy conditions whereas higher values, ranging from 9 to 21 degrees C, were registered during fog-free periods. Additionally, during the periods when fog water was collected, global solar radiation values were linearly related (r2=0.831) to those under fog-free conditions, such that there was a 75+/-1% reduction in median radiation in response to fog. Fog events greatly reduced median diurnal tree transpiration, with rates about 30 times lower than that during fog-free conditions and approximating the nighttime rates in both species studied (the needle-like leaf Erica arborea L. and the broadleaf Myrica faya Ait.). This large decrease in transpiration in response to fog was independent of the time of the day, tree size and species and micrometeorological status, both when expressed on a median basis and in cumulative terms for the entire 10-month measuring period. We conclude that, in contrast to the turbulent deposition of fog water droplets on the heath-laurel species, which may be regarded as a localized hydrological phenomenon that is important for high-altitude wind-exposed E. arborea trees, the cooler, wetter and shaded microenvironment provided by the cloud immersion belt represents a large-scale effect that is crucial for reducing the transpirational water loss of trees that have profligate water use, such as those of the 'laurisilva'. PMID:19203969

  1. A simple framework to analyze water constraints on seasonal transpiration in rubber tree (Hevea brasiliensis) plantations

    PubMed Central

    Sopharat, Jessada; Gay, Frederic; Thaler, Philippe; Sdoodee, Sayan; Isarangkool Na Ayutthaya, Supat; Tanavud, Charlchai; Hammecker, Claude; Do, Frederic C.

    2015-01-01

    Climate change and fast extension in climatically suboptimal areas threaten the sustainability of rubber tree cultivation. A simple framework based on reduction factors of potential transpiration was tested to evaluate the water constraints on seasonal transpiration in tropical sub-humid climates, according pedoclimatic conditions. We selected a representative, mature stand in a drought-prone area. Tree transpiration, evaporative demand and soil water availability were measured every day over 15 months. The results showed that basic relationships with evaporative demand, leaf area index and soil water availability were globally supported. However, the implementation of a regulation of transpiration at high evaporative demand whatever soil water availability was necessary to avoid large overestimates of transpiration. The details of regulation were confirmed by the analysis of canopy conductance response to vapor pressure deficit. The final objective of providing hierarchy between the main regulation factors of seasonal and annual transpiration was achieved. In the tested environmental conditions, the impact of atmospheric drought appeared larger importance than soil drought contrary to expectations. Our results support the interest in simple models to provide a first diagnosis of water constraints on transpiration with limited data, and to help decision making toward more sustainable rubber plantations. PMID:25610443

  2. Cyclic variations in nitrogen uptake rate in soybean plants: uptake during reproductive growth

    NASA Technical Reports Server (NTRS)

    Vessey, J. K.; Raper, C. D. Jr; Henry, L. T.; Raper CD, J. r. (Principal Investigator)

    1990-01-01

    Net uptake of NO3- by non-nodulated soybean plants [Glycine max (L.) Merr. cv. Ransom] growing in flowing hydroponic culture was measured daily during a 63 d period of reproductive development between the first florally inductive photoperiod and [unknown word] seed growth. Removal of NO3- from a replenished solution containing 1.0 mol m-3 NO3- was determined by ion chromatography. Uptake of NO3- continued throughout reproductive development. The net uptake rate of NO3- cycled between maxima and minima with a periodicity of oscillation of 3 to 7 d during the floral stage and about 6 d during the fruiting stage. Coupled with increasing concentrations of carbon and C : N ratios in tissues, the oscillations in net uptake rates of NO3- are evidence that the demand for carbohydrate by reproductive organs is contingent on the availability of nitrogen in the shoot pool rather than that the demand for nitrogen follows the flux of carbohydrate into reproductive tissues.

  3. Effects of thinning on soil and tree water relations, transpiration and growth in an oak forest (Quercus petraea (Matt.) Liebl.).

    PubMed

    Bréda, N; Granier, A; Aussenac, G

    1995-05-01

    To quantify the effects of crown thinning on the water balance and growth of the stand and to analyze the ecophysiological modifications induced by canopy opening on individual tree water relations, we conducted a thinning experiment in a 43-year-old Quercus petraea stand by removing trees from the upper canopy level. Soil water content, rainfall interception, sap flow, leaf water potential and stomatal conductance were monitored for two seasons following thinning. Seasonal time courses of leaf area index (LAI) and girth increment were also measured. Predawn leaf water potential was significantly higher in trees in the thinned stand than in the closed stand, as a consequence of higher relative extractable water in the soil. The improvement in water availability in the thinned stand resulted from decreases in both interception and transpiration. From Year 1 to Year 2, an increase in transpiration was observed in the thinned stand without any modification in LAI, whereas changes in transpiration in the closed stand were accompanied by variations in LAI. The different behaviors of the closed and open canopies were interpreted in terms of coupling to the atmosphere. Thinning increased inter-tree variability in sap flow density, which was closely related to a leaf area competition index. Stomatal conductance varied little inside the crown and differences in stomatal conductance between the treatments appeared only during a water shortage and affected mainly the closed stand. Thinning enhanced tree growth as a result of a longer growing period due to the absence of summer drought and higher rates of growth. Suppressed and dominant trees benefited more from thinning than trees in the codominant classes. PMID:14965953

  4. Thermal transpiration of a slightly rarefied gas through a horizontal straight pipe in the presence of weak gravitation

    NASA Astrophysics Data System (ADS)

    Doi, Toshiyuki

    2013-10-01

    Thermal transpiration of a slightly rarefied gas through a horizontal straight pipe in the presence of weak gravitation is studied on the basis of kinetic theory. We consider the situation in which the Knudsen number (the mean free path divided by the characteristic length of the cross section) is small and the dimensionless gravity (the characteristic length divided by the ascent height of the molecules against gravity) is of the order of the square of the Knudsen number. The behavior of the gas is studied analytically on the basis of the fluid-dynamic-type equation and the slip-type boundary condition derived from the Boltzmann equation for small Knudsen numbers. Extending the analysis of the two-dimensional channel problem, the solution for a pipe with an arbitrary cross section is obtained in a semianalytical form. When the temperature gradient is imposed along the pipe, the pressure gradient is produced not only in the vertical direction but also in the horizontal direction due to the effect of gravity. Although this pressure gradient is of the order of the square of the Knudsen number, it induces a flow of the order of the Knudsen number. As a result, the apparently higher order effect of gravity produces a relatively finite effect on thermal transpiration. This phenomenon, first observed in plane thermal transpiration, is clarified for a pipe with a general cross section. The explicit solution is obtained for the pipe with the cross section of an annulus between eccentric circular cylinders. Based on the solution, the effect of weak gravitation on the mass flow rate of the gas, as well as on the flow velocity, is clarified over a wide range of the radii ratio and the eccentricity of the cylinders.

  5. Modeling the Impact of Land Use Change on Regional Water Flux in Northern Wisconsin-Species Effects on Transpiration and Canopy Average Stomatal Conductance

    NASA Astrophysics Data System (ADS)

    Ewers, B. E.; Mackay, D. S.; Ahl, D. E.; Burrows, S. N.; Samanta, S. S.; Gower, S. T.

    2001-05-01

    Land use change has created a diversity of forest cover types in northern Wisconsin. Our objective was to determine if changes in forest cover would result in a significant change in regional water flux. To adequately sample these forest cover types we chose four cover types red pine, sugar maple/basswood, quaking aspen/balsam fir, and northern white-cedar/balsam fir/green alder that represent more than 80 percent of the ground area. The remainder of the ground area is mostly non-forested grassland, shrubland, and open water. Within each cover type we measured sap flux of 8 trees of each species. We scaled point measurements of sap flux to tree transpiration using sensors positioned radially into the conducting sapwood and on both the north and south sides of the tree. We found that aspen/balsam fir had the highest average daily transpiration rates. There was no difference in the northern white-cedar/balsam fir/green alder and red pine cover types. The sugar maple/basswood cover type had the lowest daily average transpiration rate. These changes in transpiration could not be explained by differences in leaf area index. Thus, we calculated canopy average stomatal conductance (GS) using an inversion of the Penman-Monteith equation and tree leaf area. We modified a regional hydrology model to include a simple tree hydraulic sub-model that assumes stomatal regulation of leaf water potential. We tested the behavior of the sub-model by evaluating GS response to vapor pressure deficit, radiation, temperature, and soil moisture for each species. We hypothesize that species with a high canopy average stomatal conductance at low vapor pressure deficit will have to have greater sensitivity to vapor pressure deficit in order to maintain minimal leaf water potential as suggested by the model. Our results indicate that changes to forest cover such as conversion from low transpiring sugar maple/basswood to high transpiring aspen/fir will result in predictable changes to the regional water balance of northern Wisconsin.

  6. Visitation rates and pollinator sets at the periphery and central parts of single-species plant patches

    Microsoft Academic Search

    S. N. Lysenkov

    2009-01-01

    Three model plant species (Aegopodium podagraria, Tripleurospermum inodorum, and Geranium palustri) were used to show the differences in visitation rates and pollinator sets between plant individuals growing at the center\\u000a and periphery of single-species patches. Most of the insect species visited the center more frequently, but Phaonia basalis (Diptera, Muscidae) and Leptura flava (Coleoptera, Cerambycidae) preferred the peripheral parts. The

  7. An in vivo root hair assay for determining rates of apoptotic-like programmed cell death in plants

    PubMed Central

    2011-01-01

    In Arabidopsis thaliana we demonstrate that dying root hairs provide an easy and rapid in vivo model for the morphological identification of apoptotic-like programmed cell death (AL-PCD) in plants. The model described here is transferable between species, can be used to investigate rates of AL-PCD in response to various treatments and to identify modulation of AL-PCD rates in mutant/transgenic plant lines facilitating rapid screening of mutant populations in order to identify genes involved in AL-PCD regulation. PMID:22165954

  8. Heat pulse observations of Eucalyptus grandis transpiration in South Africa

    SciTech Connect

    Dye, P.J.; Olbrich, B.W. [CSIR, Sabie (South Africa). Sabie Forestry Research Center

    1992-12-31

    Forest plantations in South Africa are currently limited to areas experiencing a minimum mean annual rainfall of 800 mm, and cover approximately 1.18 million ha. Of this total area, 37% is planted to Eucalyptus spp., of which 76% comprise E. grandis Hill ex Maiden. Micrometeorological methods of measuring evapotranspiration are impractical in many areas of South African forestry owing to the rugged topography and heterogeneous canopy and boundary layer conditions. The heat pulse velocity (HPV) technique shows great promise as a suitable method of measuring sap flow in even-aged forest plantations. This paper describes the method in detail, as well as the results of comparisons between HPV sap flow estimates and cut-tree uptake rates for two size classes of E. grandis.

  9. Effect of elevated atmospheric carbon dioxide and open-top chambers on transpiration in a tallgrass prairie

    SciTech Connect

    Bremer, D.J.; Ham, J.M.; Owensby, C.E. [Kansas State Univ., Manhattan, KS (United States)

    1996-07-01

    Increasing concentrations of atmospheric carbon dioxide (CO{sub 2}) may influence plant-water relations in natural and agricultural ecosystems. A tallgrass prairie near Manhattan, KS, was exposed to elevated atmospheric CO{sub 2} using open-top chambers (OTCs). Heat balance sap flow gauges were used to measure transpiration in ironweed [Vernonia baldwini var. interior (Small) Schub.], aC{sub 3}forb, and on individual grass culms of big bluestem (Andropogan geradii Vitman) and indiangrass [Sorghastrum nutans (L>) Nash], both C{sub 4} grasses, in each of three treatments: (1) CE (chamber enriched, 2x ambient CO{sub 2}); (2) CA (chamber ambient, no CO{sub 2} enrichment); and (3) NC (no chamber, no CO{sub 2} enrichment). Sap flow data were coupled with measurements of stomatal conductance, plant/canopy resistance, and whole-chamber evapotranspiration (ET) to determine the effect of elevated CO{sub 2} on water use at different scales. Because of frequent rainfall during the study, all data were collected under well-watered conditions. Comparisons of CE and CA showed that sap flow was reduced by 33% in ironweed, 18% in big bluestem, and 22% in indiangrass under CO{sub 2} enrichment. Whole-chamber ET was reduced by 23 to 27% under CO{sub 2} enrichment. Comparisons of CA and NC showed that the environmental effect of the OTCs caused a 21 to 24% reduction in transpiration. Stomatal conductance decreased from 7.9 to 3.6 mm s{sup {minus}1} in big bluestem and from 5.3 to 3.2 mm s{sup {minus}1} in indiangrass under CO{sub 2} enrichment. Soil water was consistently highest under elevated CO{sub 2}, reflecting the large reductions in transpiration. During sap flow measurements, whole-plant stomatal resistance to water vapor flux in big bluestem increased from 103 to 194 s m{sup {minus}1} under elevated CO{sub 2}. 23 refs., 7 figs., 4 tabs.

  10. Wheat cultivars selected for high Fv /Fm under heat stress maintain high photosynthesis, total chlorophyll, stomatal conductance, transpiration and dry matter.

    PubMed

    Sharma, Dew Kumari; Andersen, Sven Bode; Ottosen, Carl-Otto; Rosenqvist, Eva

    2015-02-01

    The chlorophyll fluorescence parameter Fv /Fm reflects the maximum quantum efficiency of photosystem II (PSII) photochemistry and has been widely used for early stress detection in plants. Previously, we have used a three-tiered approach of phenotyping by Fv /Fm to identify naturally existing genetic variation for tolerance to severe heat stress (3 days at 40°C in controlled conditions) in wheat (Triticum aestivum L.). Here we investigated the performance of the previously selected cultivars (high and low group based on Fv /Fm value) in terms of growth and photosynthetic traits under moderate heat stress (1 week at 36/30°C day/night temperature in greenhouse) closer to natural heat waves in North-Western Europe. Dry matter accumulation after 7 days of heat stress was positively correlated to Fv /Fm . The high Fv /Fm group maintained significantly higher total chlorophyll and net photosynthetic rate (PN ) than the low group, accompanied by higher stomatal conductance (gs ), transpiration rate (E) and evaporative cooling of the leaf (?T). The difference in PN between the groups was not caused by differences in PSII capacity or gs as the variation in Fv /Fm and intracellular CO2 (Ci ) was non-significant under the given heat stress. This study validated that our three-tiered approach of phenotyping by Fv /Fm performed under increasing severity of heat was successful in identifying wheat cultivars differing in photosynthesis under moderate and agronomically more relevant heat stress. The identified cultivars may serve as a valuable resource for further studies to understand the physiological mechanisms underlying the genetic variability in heat sensitivity of photosynthesis. PMID:24962705

  11. Evaluating the Performance and Economics of Transpired Solar Collectors for Commercial Applications

    SciTech Connect

    Kozubal, E.; Deru, M.; Slayzak, S.; Norton, P.; Barker, G.; McClendon, J.

    2008-01-01

    Using transpired solar collectors to preheat ventilation air has recently become recognized as an economic alternative for integrating renewable energy into commercial buildings in heating climates. The collectors have relatively low installed costs and operate on simple principles. Theory and performance testing have shown that solar collection efficiency can exceed 70% of incident solar. However, implementation and current absorber designs have adversely affected the efficiency and associated economics from this initial analysis. The National Renewable Energy Laboratory (NREL) has actively studied this technology and monitored performance at several installations. A calibrated model that uses typical meteorological weather data to determine absorber plate efficiency resulted from this work. With this model, an economic analysis across heating climates was done to show the effects of collector size, tilt, azimuth, and absorptivity. The analysis relates the internal rate of return of a system based on the cost of the installed absorber area. In general, colder and higher latitude climates return a higher rate of return because the heating season extends into months with good solar resource. Wal-Mart has installed approximately 8,000 ft{sup 2} of absorber at its experimental store in Aurora, Colorado. The delivered energy efficiency was measured at 8-11% during January and February 2007. The low collection efficiency is largely due to the oversized absorber and to the multizone control strategy that limits the amount of air pulled through the collector. Analysis shows that more than 50% of the incident solar energy could be delivered with proper control strategy changes.

  12. Evaluating the Performance and Economics of Transpired Solar Collectors for Commercial Applications: Preprint

    SciTech Connect

    Kozubal, E.; Deru, M.; Slayzak, S.; Norton, P.; Barker, G.; McClendon, J,

    2008-07-01

    Using transpired solar collectors to preheat ventilation air has recently become recognized as an economic alternative for integrating renewable energy into commercial buildings in heating climates. The collectors have relatively low installed costs and operate on simple principles. Theory and performance testing have shown that solar collection efficiency can exceed 70% of incident solar. However, implementation and current absorber designs have adversely affected the efficiency and associated economics from this initial analysis. The National Renewable Energy Laboratory has actively studied this technology and monitored performance at several installations. A calibrated model that uses typical meteorological weather data to determine absorber plate efficiency resulted from this work. With this model, an economic analysis across heating climates was done to show the effects of collector size, tilt, azimuth, and absorptivity. The analysis relates the internal rate of return of a system based on the cost of the installed absorber area. In general, colder and higher latitude climates return a higher rate of return because the heating season extends into months with good solar resource.

  13. On the spatial distribution of the transpiration and soil moisture of a Mediterranean heterogeneous ecosystem in water-limited conditions.

    NASA Astrophysics Data System (ADS)

    Curreli, Matteo; Corona, Roberto; Montaldo, Nicola; Albertson, John D.; Oren, Ram

    2014-05-01

    Mediterranean ecosystems are characterized by a strong heterogeneity, and often by water-limited conditions. In these conditions contrasting plant functional types (PFT, e.g. grass and woody vegetation) compete for the water use. Both the vegetation cover spatial distribution and the soil properties impact the soil moisture (SM) spatial distribution. Indeed, vegetation cover density and type affects evapotranspiration (ET), which is the main lack of the soil water balance in these ecosystems. With the objective to carefully estimate SM and ET spatial distribution in a Mediterranean water-limited ecosystem and understanding SM and ET relationships, an extended field campaign is carried out. The study was performed in a heterogeneous ecosystem in Orroli, Sardinia (Italy). The experimental site is a typical Mediterranean ecosystem where the vegetation is distributed in patches of woody vegetation (wild olives mainly) and grass. Soil depth is low and spatially varies between 10 cm and 40 cm, without any correlation with the vegetation spatial distribution. ET, land-surface fluxes and CO2 fluxes are estimated by an eddy covariance technique based micrometeorological tower. But in heterogeneous ecosystems a key assumption of the eddy covariance theory, the homogeneity of the surface, is not preserved and the ET estimate may be not correct. Hence, we estimate ET of the woody vegetation using the thermal dissipation method (i.e. sap flow technique) for comparing the two methodologies. Due the high heterogeneity of the vegetation and soil properties of the field a total of 54 sap flux sensors were installed. 14 clumps of wild olives within the eddy covariance footprint were identified as the most representative source of flux and they were instrumented with the thermal dissipation probes. Measurements of diameter at the height of sensor installation (height of 0.4 m above ground) were recorded in all the clumps. Bark thickness and sapwood depth were measured on several trees to obtain a generalized estimates of sapwood depth. The known of allometric relationships between sapwood area, diameter and canopy cover area within the eddy covariance footprint helped for the application of a reliable scaling procedure of the local sap flow estimates which are in a good agreement with the estimates of ET eddy covariance based. Soil moisture were also extensively monitored through 25 probes installed in the eddy covariance footprint. Results show that comparing eddy covariance and sap flow ET estimates eddy covariance technique is still accurate in this heterogeneous field, whereas the key assumption, surface homogeneity, is not preserved. Furthermore, interestingly wild olives still transpire at higher rates for the driest soil moisture conditions, confirming the hydraulic redistribution from soil below the roots, and from roots penetrating deep cracks in the underlying basalt parent rock.

  14. 7-88 A geothermal power plant uses geothermal liquid water at 160C at a specified rate as the heat source. The actual and maximum possible thermal efficiencies and the rate of heat rejected from this power plant

    E-print Network

    Bahrami, Majid

    7-31 7-88 A geothermal power plant uses geothermal liquid water at 160ºC at a specified rate and potential energy changes are zero. 3 Steam properties are used for geothermal water. Properties Using saturated liquid properties, the source and the sink state enthalpies of geothermal water are (Table A-4) k

  15. Comparative estimates of transpiration of ash and beech forest at a chalk site in southern Britain

    NASA Astrophysics Data System (ADS)

    Roberts, John; Rosier, Paul T. W.

    1994-11-01

    (1) During the dry summer of 1989 stomatal conductance ( gs), boundary-layer conductance ( ga), leaf water and osmotic potentials ( ?1, ??) and leaf area index ( L?) measurements were made in mature ash and beech stands growing on shallow soil over chalk near Winchester, Hampshire, UK. In addition measurements of gs and L? were made in the understorey layer in the ash stand, comprised mainly of dog's mercury, hazel and bramble. Automatic weather stations located (i) above the beech stand and (ii) at the understorey level (within the ash stand) provided hourly averages of weather variables. Changes in soil moisture deficit in both stands were determined from regular measurements made with a neutron probe. (2) Maximum values of gs (up to 0.3 mol m -2 s -1) were found at the top of the ash and beech canopies at the start of the day, while at the canopy base gs was about half of these values. At all canopy levels the value of gs was more closely associated with specific humidity deficit (at the time of measurement) than with any other weather variable, and there was no relationship between gs and soil mositure deficit or leaf water status, described by ?1 and ?? on the day of measurement. (3) Values of gs of the understorey plants were only half those of the tree species and changed less during the day. However, seasonal changes in gs of dog's mercury did seem to be associated with increased soil moisture deficit. (4) Estimates of L? in the ash and beech stands were made from leaf litter collections and partitioned into canopy layers using ratios determined by destructive sampling. L? of the beech stand was 5.3 and for the ash stand 2.7. L? of the understorey varied seasonally and rose to a peak of 3 in June falling gradually for the remainder of the summer period. (5) Hourly values of gs and ga in each stand for each canopy layer were scaled up to the canopy by using L? of the individual canopy layers (including the understorey level in the ash stand) and were combined with values of net radiation, temperature and specific humidity deficit in a multi-layer formulation of the Penman-Monteith equation (Monteith, 1965) to estimate stand transpiration. Averaged over 1990 and 1991, the annual transpiration loss from the ash stand was 407 mm and from the beech stand 393 mm. The average understorey contribution to the total loss from the ash stand was 45% over a year, being around 25 to 30% when the trees were in leaf.

  16. A Rating of Plants with Reference to their Relative Resistance or Susceptibility to Phymatotrichum Root Rot.

    E-print Network

    Taubenhaus, J. J. (Jacob Joseph); Ezekiel, Walter N. (Walter Naphtali)

    1936-01-01

    juniper + sabina horizontalis..Trailing juniper + + ........ ...... sabina prostrata Creeping juniper scopulorum R* Mountain ++ ................ juniper .................... v*iniana .................. Red cedar .................. $ decidua... trees, ornamental shrubs, or plants to be grown in root-rot areas, it is of great importance low the relative susceptibility or resistance of plants to the ge. This bulletin furnishes such information for 2,116 species bspecies of plants belonging...

  17. Evaluation of Ability to Determine Transpiration Fraction from Stable Water Isotopes by Synthesis of Models and Observations in an Alpine Forest

    NASA Astrophysics Data System (ADS)

    Wong, T.; Berkelhammer, M. B.; Noone, D. C.

    2013-12-01

    The partitioning of latent heat flux into contributions from ground evaporation and plant transpiration in land surface models is a key feature of any hydrological scheme, but notoriously difficult to resolve. Global scale models show significant differences in the terrestrial energy balance, which can be traced to poor constraints on the pathways of water that control evapotranspiration (ET). In addition, the depth of water uptake has been shown to be correlated with ecosystem ET partitioning, but vegetation rooting profiles are difficult to observe and therefore present a significant source of uncertainty. Stable isotope ratios in water from soil, leaves and water vapor have been used to help constrain the ET partitioning and to track water movement in ecosystems, but many previous studies have been limited in two regards: 1) lack of sufficient data to provide true closure, and 2) lack of an adequate modeling framework to incorporate many of the processes which control ET. We present results for the partitioning of ET from an isotopically-enabled land surface model (ISOLSM) that is driven by meteorological, hydrological and isotopic data collected at the Manitou Experimental Forest during the summer and autumn of 2011. An ensemble of 394 realizations has been produced, constrained by observations of latent heat, sensible heat and CO2 fluxes. Even when all three flux constraints are met, the transpiration fraction is not well-constrained. These experiments show that previous work using isotopic observations likely has significant uncertainty in their ET partitioning estimates. However, root-weighted soil isotope values have proven to sufficiently provide a final constraint on transpiration fraction, and an investigation of the time scales associated with this constraint is conducted. A sensitivity analysis of rooting profile and ET partitioning reveals the soil isotope ratios, and therefore the estimate of transpiration fraction, depend strongly on the rooting profile.

  18. Relative in vitro growth rates of duckweeds (Lemnaceae) - the most rapidly growing higher plants.

    PubMed

    Ziegler, P; Adelmann, K; Zimmer, S; Schmidt, C; Appenroth, K-J

    2015-01-01

    Relative growth rates (RGR), doubling times (DT) and relative weekly yields (RY) of 39 clones (ecotypes) from 13 species representing all five genera of duckweeds were determined under standardised cultivation conditions. RGR ranged overall from 0.153 to 0.519 day(-1) , DT from 1.34 to 4.54 days and RY from 2.9 to 37.8 week(-1) . The RGR and RY data can be compared directly to other published findings to only a limited extent on account of missing clonal designations for and limited accessibility to previously investigated clones, as well as the use of different data denominators. However, they are consistent with the published results of other comparative duckweed studies of similar scope in showing that RGR does not vary primarily at the level of the genus or species, but rather reflects the adaptation of individual clones to specific local conditions. The RGR data support the widely held assumption that duckweeds can grow faster than other higher plants and that they can thus surpass land-based agricultural crops in productivity. Duckweeds are highly promising for the production of biomass for nutrition and energy, but extensive clonal comparison will be required to identify the most suitable isolates for this purpose. PMID:24803032

  19. Growth and Responses of Castor Oil Plant to Sources and Rates of Organic Manures in Ferralitic Soils

    Microsoft Academic Search

    R. A. E. Ugbaja

    1996-01-01

    Four organic manures and NPK fertilizer, each at four rates, were assessed under field conditions for their comparative effects on the growth and yield of castor oil plant. Castor seed yields (5.11 and 5.01 t ha) were greatest with poultry or swine manure applied at the rate of 10 t ha. Yields of 4.01 or 4.00 t ha were obtained

  20. Influence of soil moisture stress on transpiration from a grain sorghum canopy

    E-print Network

    Moridis, George Julius

    1982-01-01

    INFLUENCE OF SOIL MOISTURE STRESS ON TRANSPIRATION FROM A GRAIN SORGHUM CANOPY A Thesis by GEORGE JULIUS MORIDIS Submitted to the Graduate College of Texas ASM University in partial fulfillment of the requirement for t1 e degree of MASTER... OF SCIENCE December 1982 Major Subject: Agricultural Engineering INFLUENCE OF SOIL MOISTURE STRESS ON TRANSPIRATION FROM A GRAIN SORGHUM CANOPY A Thesis by GEORGE JULIUS MORIDIS Approved as to style and content by: Chairman of Commattee) (Head...

  1. An optimally designed stack effluent sampling system with transpiration for active transmission enhancement

    E-print Network

    Schroeder, Troy J.

    1995-01-01

    AN OPTIMALLY DESIGNED STACK EFFLUENT SAMPLING SYSTEM WITH TRANSPIRATION FOR ACTIVE TRANSMISSION ENHANCEMENT TROY J. SCHROEDER Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements... for the degree of MASTER OF SCIENCE December 1995 Major Subject: Mechanical Engineering AN OPTIMALLY DESIGNED STACK EFFLUENT SAMPLING SYSTEM WITH TRANSPIRATION FOR ACTIVE TRANSMISSION ENHANCEMENT A Thesis by Troy J. Schroeder Submitted to the Office...

  2. The sensitivity of regional transpiration to land-surface characteristics: significance of feedback

    Microsoft Academic Search

    C. M. J. Jacobs; Bruin de H. A. R

    1992-01-01

    Several authors have determined the sensitivity of transpiration to different environmental parameters using the Penman-Monteith equation. In their studies the interaction between transpiration and, for example, the humidity of the air is ignored: the feedback with the planetary boundary layer (PBL) is not accounted for. Furthermore, surface-layer (SL) feedback (e.g., stability effects in the surface layer) is often neglected.In our

  3. Transpiration of a 64-year-old maritime pine stand in Portugal

    Microsoft Academic Search

    D. Loustau; P. Berbigier; P. Roumagnac; C. Arruda-Pacheco; J. S. David; M. I. Ferreira; J. S. Pereira; R. Tavares

    1996-01-01

    The transpiration, sap flow, stomatal conductance and water relations ofPinus pinaster were determined during spring and summer in a 64-year-old stand in Ribatejo (Portugal). The transpiration of the pine canopy was determined from sap flow or eddy covariance techniques. Canopy conductance values (gc) were estimated from inversion methods using eddy covariance or sap flow data, respectively, and from scaling-up methods

  4. Plants

    NSDL National Science Digital Library

    Miss Berneski

    2011-12-10

    Get ready to explore plants! Let's Learn About Plants! Question: What do plants need to live? Watch the video to find out! What does it need to grow? Question: What are the parts of a plant? Click to find out! Parts of a Plant Question: What is the life cycle of a plant? Watch the video to find out! Plant Life Cycle Video Question: ...

  5. The sensitivity of regional transpiration to land-surface characteristics: Significance of feedback

    SciTech Connect

    Jacobs, C.M.J.; De Bruin, H.A.R. (Agricultural Univ., Wageningen (Netherlands))

    1992-07-01

    Several authors have determined the sensitivity of transpiration to different environmental parameters using the Penman-Monteith equation. In their studies, the interaction between transpiration and, for example, the humidity of the air is ignored: the feedback with the planetary boundary layer (PBL) is not accounted for. Furthermore, surface-layer (SL) feedback (e.g., stability effects in the surface layer) is often neglected. In our study, both PBL feedback and SL feedback are accounted for by coupling the big-leaf model to a detailed model for the PBL. This study provides an analysis of the sensitivity of transpiration to net radiation calculated after an albedo change, aerodynamic resistance calculated after a change in the aerodynamic roughness, and surface resistance. It is shown that PBL feedback affects the sensitivity of transpiration to the tested variables significantly. The sensitivity of transpiration to surface resistance and to aerodynamic resistance, or aerodynamic roughness, is decreased by the PBL feedback. In contrast, PBL feedback enlarges the sensitivity of transpiration to the net radiation, or albeds, and appears to be highly dependent on the specific conditions, especially on the aerodynamic roughness of the vegetation. It is recommended that future sensitivity studies for prognostic use account for PBL feedback.

  6. Importance of deposition velocity for sulfur gas to sulfate particle transformation rates at the four corners power plant

    NASA Astrophysics Data System (ADS)

    Sievering, Herman; Cooke, Jody; Pueschel, Rudolf

    Sulfate (SO 4) is known to contribute to visibility degradation. The rate of sulfur dioxide (SO 2) transformation to SO 4 in the real atmosphere is, therefore, a very important measurement parameter and model component. The rate of deposition or deposition velocity ( vd) to the ground influences the determination of the SO 2?SO 4 rate, and must therefore be carefully stated. vd has rarely been consistently defined or carefully considered in transformation rate estimations. This paper will discuss the effect of uncertainty in our knowledge of vd values on previously estimated transformation rates. Emphasis will be placed on a data base for the Four Corners power plant located in Farmington, New Mexico. This power plant is situated in the broad valley of the San Juan River having relative humidity rarely above 40% and with the power plant being the predominant source of anthropogenic particles in the valley. Thus, transformation rates are expected to be less variable than in environments subject to wide fluctuations in relative humidity and background pollution. Calculation of the transformation rate using earlier field studies but with the vd range for SO 2 of 0.3, 0.8 and 1.2 cm s -1 as low confidence, mean and high confidence values, results in a range of possible transformation rates from 0 to as much as 8.2% h -1. It appears that uncertainty in vd for SO 2 may hamper attempts to specify transformation rates in which plume loss to the ground is present. Given this, it is recommended that direct SO 4 measurements be taken in the plume.

  7. Comparisons among species composition, leaf area, and water relations in three shrub-steppe plant communities

    SciTech Connect

    Link, S.O.; Kirkham, R.R.; Thiede, M.E.; Downs, J.L.; Gee, G.W.

    1987-03-01

    Observations were made on plant communities dominated by Bromus tectorum (cheatgrass site), Artemisia tridentata (sagebrush site), and Grayia spinosa (hopsage site). Leaf area on a ground area basis of sagebrush was nor significantly different between the sagebrush and hopsage sites; however, the leaf area of hopsage was one-quarter that of sagebrush at the hopsage site. Pre-dawn xylem water potential of sagebrush was -2.91 MPa, while that of hopsage was -4.79 MPa. Stomatal conductance and transpiration rate of sagebrush and hopsage were nearly the same. 11 refs., 4 figs., 2 tabs.

  8. Transpiration-purged optical probe: a novel sensor for high temperature harsh environments

    SciTech Connect

    VanOsdol, J.G.; Woodruff, S.D.; Straub, D.L.

    2007-10-05

    Typical control systems that are found in modern power plants must control the many physical aspects of the complex processes that occur inside the various components of the power plant. As detection and monitoring of pollutants becomes increasingly important to plant operation, these control systems will become increasingly complex, and will depend upon accurate monitoring of the concentration levels of the various chemical species that are found in the gas streams. In many cases this monitoring can be done optically. Optical access can also be used to measure thermal emissions and the particulate loading levels in the fluid streams. Some typical environments were optical access is needed are combustion chambers, reactor vessels, the gas and solid flows in fluidized beds, hot gas filters and heat exchangers. These applications all have harsh environments that are at high temperatures and pressures. They are often laden with products of combustion and other fine particulate matter which is destructive to any optical window that could be used to monitor the processes in these environments in order to apply some control scheme over the process. The dust and char that normally collects on the optical surfaces reduces the optical quality and thus impairs the ability of the optical surface to transmit data. Once this has occurred, there is generally no way to clean the optical surface during operation. The probe must be dismounted from the vessel, disassembled and cleaned or replaced, then remounted. This would require the shutdown of the particular component of the plant where optical monitoring is required. This renders the probe ineffective to be used as the monitoring part of any control system application. The components of optical monitoring equipment are usually built in supporting structures that require precise alignment. This is almost always accomplished using fine scale adjustments to specialized mounting hardware that is attached to the reactor vessel. When the temperature of these supporting structures increases due to the high temperature process that is occurring inside the vessel, the optical alignment can often suffer due to the thermal expansion of the mounting structure. This can render them useless especially for gas velocity measurements or other situations where precise optical alignment is required. What is needed is an optical probe that can be inserted into any hazardous environment that will not suffer alignment problems or other failure modes that are related to high temperature dirty environments, and at the same time maintain a clean optical surface through the lifetime of the devise so that it may be continually used for optical inspection or for control system applications. This paper describes details of the construction and the use of a transpiration purged optical probe which mitigates the problems that are outlined above. The transpiration probe may be used as either an emitter or a detector. The probe is implemented in the harsh high temperature environment of the NETL pulsed combustion system where products of combustion and particulate matter have been shown to degrade the performance of a normal optical window. Assessments of combustion heat release are made by monitoring the ultraviolet signatures that are produced by the concentration of OH during a pulsed combustion process. It is shown that these measurements are directly correlated with the pressure within the pulsed combustor. Probe temperature measurements are also presented to show how the probe and its mounting hardware remain at constant temperatures well below the high temperature environment which they monitor.

  9. Selecting Plants and Nitrogen Rates to Vegetate Crude-Oil–Contaminated Soil

    Microsoft Academic Search

    W. D. Kirkpatrick; P. M. White Jr; D. C. Wolf; G. J. Thoma; C. M. Reynolds

    2006-01-01

    Phytoremediation can be effective for remediating contaminated soils in situ and generally requires the addition of nitrogen (N) to increase plant growth. Our research objectives were to evaluate seedling emergence and survival of plant species and to determine the effects of N additions on plant growth in crude-oil–contaminated soil. From a preliminary survival study, three warm-season grasses—pearlmillet (Pennisetum glaucum [L.

  10. Using tree ring data as a proxy for transpiration to reduce predictive uncertainty of a model simulating groundwater-surface water-vegetation interactions

    NASA Astrophysics Data System (ADS)

    Schilling, O. S.; Doherty, J.; Kinzelbach, W.; Wang, H.; Yang, P. N.; Brunner, P.

    2014-11-01

    The interactions between surface water, the vadose zone, groundwater, and vegetation are governed by complex feedback mechanisms. Numerical models simulating these interactions are essential in quantifying these processes. However, the notorious lack of field observations results in highly uncertain parameterizations. We suggest a new type of observation data to be included in the calibration data set for hydrological models simulating interactions with vegetation: Tree rings as a proxy for transpiration. We use the lower Tarim River as an example site for our approach. In order to forestall the loss of riparian ecosystems from reduced flow over a 300 km reach of the lower Tarim River, the Chinese government initiated periodical, ecological water releases. The water exchange processes in this region were simulated for a cross-section on the lower reaches of the Tarim River using a numerical model (Hydro-GeoSphere) calibrated against observations of water tables, as well as transpiration estimated from tree ring growth. A predictive uncertainty analysis quantifying the worth of different components of the observation dataset in reducing the uncertainty of model predictions was carried out. The flow of information from elements of the calibration dataset to the different parameters employed by the model was also evaluated. The flow of information and the uncertainty analysis demonstrate that tree ring records can significantly improve confidence in modeling ecosystem dynamics, even if these transpiration estimates are uncertain. To use the full potential of the historical information encapsulated in the Tarim River tree rings, however, the relationship between tree ring growth and transpiration rates has to be studied further.

  11. Coupled hydraulic and photosynthetic feedbacks on forest transpiration throughout the growing season

    NASA Astrophysics Data System (ADS)

    Mackay, D. S.; Ewers, B. E.

    2007-12-01

    Ecosystem models account for vegetative controls on water fluxes using environmental drivers and hydraulic and/or biochemical limits on canopy stomatal conductance (Gs), variations in space and time of leaf area index (L), and species or biome specific parameters. However, some parameters, such as maximum stomatal conductance or its reference proxy at vapor pressure deficit of 1 kPa (Gsref), may not be strictly time-independent suggesting as yet undefined mechanisms in the models. We developed a model of coupled canopy water and carbon exchange, which allowed us to examine photosynthetic and hydraulic feedbacks on Gsref spanning the whole growing season for several dominant tree species in wetland and upland positions that collectively account for most a 1600 square km region centered on the WLEF AmeriFlux tower in Wisconsin, USA. The model assimilated half-hourly sap flux and micrometeorological data to quantify and explain temporal variations in Gsref for trembling aspen, sugar maple, and red pine in upland sites, and speckled alder and white cedar in wetland sites. Results show (1) phenological effects on photosynthetic activity with feedback on Gsref in all species, and (2) lags of up to two months between maximum per unit leaf area photosynthetic rates for conifer versus deciduous species. These results show that for given environmental conditions canopy transpiration depends on both L and timing of biochemical activation, both of which have implications for regional ecosystem water cycling.

  12. Expansion and photosynthetic rate of leaves of soybean plants during onset of and recovery from nitrogen stress

    NASA Technical Reports Server (NTRS)

    Tolley-Henry, L.; Raper, C. D. Jr; Raper CD, J. r. (Principal Investigator)

    1986-01-01

    This study reports on the effects of nitrogen stress and restoration of nitrogen availability after a period of stress on expansion and photosynthetic rate of soybean leaves of differing maturity. We hypothesized that nitrogen resupply would lead to additional accumulation of reduced nitrogen in the leaves and, ultimately, resumption of leaf initiation and expansion and photosynthetic activity. In continuously nitrogen-stressed plants, expansion of middle trifoliolates of main-stem trifoliates and leaf area at full expansion were severely restricted. Leaves showing the greatest effects were initiated after removal of nitrogen. When the reduced nitrogen concentration in mature leaves of continuously stressed plants fell below 9 mg dm-2, the photosynthetic rate per unit leaf decreased rapidly, reaching a minimum of ca. 6-8 mg dm-2 h-1. The older mature leaves tended to abscise at this point, while the youngest leaves remained on the plant and continued to photosynthesize slowly. When nitrogen was resupplied, leaf expansion and final leaf area increased. Leaf initiation was also stimulated as reduced nitrogen levels rose in the leaves. Photosynthetic rates of the oldest and youngest pair of mature leaves returned to values comparable to those of similar-aged leaves of nonstressed soybean plants.

  13. Age Demographics, Hiring Trends, and Graduation Rates in Plant Pathology in the United States

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We examined the status of plant pathology departments and age demographics of the profession. Seven of eight large departments have lost from 17 to 40% of their faculty positions since 1987, and several smaller graduate programs in plant pathology (e.g., in several northeastern states) have all but...

  14. Decomposition and nutrient liberation rates of plant material in the Parana medio River (Argentina)

    Microsoft Academic Search

    M. Leguizamon; J. Hammerly; M. A. Maine; N. Sufie; M. J. Pizarro

    1992-01-01

    The degradation of plant material was studied in order to obtain degradation coefficients and nutrient release kinetics of the vegetation that will be submerged during the filling of the future Parana Medio man-made lake. A group of 13 plant species representative of the whole vegetation of the area were chosen.

  15. Effects of billet planting rate and position on sugarcane yields in Louisiana

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The successful implementation of sugarcane billet planting would offer Louisiana producers several potential economic advantages including reduced labor and equipment costs. Two factors that are preventing the adoption of billet planting are the higher seed cane costs associated with billet plantin...

  16. Quantification of excess water loss in plant canopies warmed with infrared heating.

    PubMed

    De Boeck, Hans J; Kimball, Bruce A; Miglietta, Franco; Nijs, Ivan

    2012-09-01

    Here we investigate the extent to which infrared heating used to warm plant canopies in climate manipulation experiments increases transpiration. Concerns regarding the impact of the infrared heater technique on the water balance have been raised before, but a quantification is lacking. We calculate transpiration rates under infrared heaters and compare these with air warming at constant relative humidity. As infrared heating primarily warms the leaves and not the air, this method increases both the gradient and the conductance for water vapour. Stomatal conductance is determined both independently of vapour pressure differences and as a function thereof, while boundary layer conductance is calculated using several approaches. We argue that none of these approaches is fully accurate, and opt to present results as an interval in which the actual water loss is likely to be found. For typical conditions in a temperate climate, our results suggest a 12-15% increase in transpiration under infrared heaters for a 1 °C warming. This effect decreases when stomatal conductance is allowed to vary with the vapour pressure difference. Importantly, the artefact is less of a concern when simulating heat waves. The higher atmospheric water demand underneath the heaters reflects naturally occurring increases of potential evapotranspiration during heat waves resulting from atmospheric feedback. While air warming encompasses no increases in transpiration, this fully depends on the ability to keep humidity constant, which in the case of greenhouses requires the presence of an air humidification system. As various artefacts have been associated with chamber experiments, we argue that manipulating climate in the field should be prioritized, while striving to limit confounding factors. The excess water loss underneath infrared heaters reported upon here could be compensated by increasing irrigation or applying newly developed techniques for increasing air humidity in the field. PMID:24501063

  17. Transpiration coefficient and ratio of transpiration to evapotranspiration of pear tree (Pyrus communis L.) under alternative partial root-zone drying conditions

    NASA Astrophysics Data System (ADS)

    Kang, Shaozhong; Hu, Xiaotao; Du, Taisheng; Zhang, Jianhua; Jerie, Peter

    2003-04-01

    Transpiration coefficient Kcb, crop coefficient Kc, and the ratio of transpiration to evapotranspiration (T/ET) are important parameters for pear orchard irrigation management and may vary with different methods of irrigation. This study investigated their changes under three irrigation methods: conventional flood irrigation (CFI), fixed partial root-zone drying and irrigation (FPRD) and alternative partial root-zone drying and irrigation (APRD), in a semi-arid region of Victoria, Australia. The average seasonal ET was 865·29, 795·63 and 804·72 mm respectively for CFI, FPRD, and APRD with ET0 of 817·59 mm for the pear fruiting season. The seasonal transpiration accounted for 81·1%, 84·4%, and 84·1% of evapotranspiration for CFI, FPRD, and APRD respectively. For the CFI, FPRD, and APRD treatments, the seasonal average Kc were 1·058, 0·973, and 0·984 (with their maximum values of 1·326, 1·211, and 1·257) respectively similarly, the respective seasonal average Kcb were 0·858, 0·822, and 0·828 (with maximum values of 1·059, 1·024, and 1·054). The relationships between Kcb, Kc, transpiration to evapotranspiration, and reduce transpiration coefficient and crop coefficient. Such effects should help improve of water-use efficiency in pear orchards.

  18. Multivariate genetic analysis of plant responses to water deficit and high temperature revealed contrasting adaptive strategies.

    PubMed

    Vasseur, François; Bontpart, Thibaut; Dauzat, Myriam; Granier, Christine; Vile, Denis

    2014-12-01

    How genetic factors control plant performance under stressful environmental conditions is a central question in ecology and for crop breeding. A multivariate framework was developed to examine the genetic architecture of performance-related traits in response to interacting environmental stresses. Ecophysiological and life history traits were quantified in the Arabidopsis thaliana Ler × Cvi mapping population exposed to constant soil water deficit and high air temperature. The plasticity of the genetic variance-covariance matrix (G-matrix) was examined using mixed-effects models after regression into principal components. Quantitative trait locus (QTL) analysis was performed on the predictors of genotype effects and genotype by environment interactions (G × E). Three QTLs previously identified for flowering time had antagonistic G × E effects on carbon acquisition and the other traits (phenology, growth, leaf morphology, and transpiration). This resulted in a size-dependent response of water use efficiency (WUE) to high temperature but not soil water deficit, indicating that most of the plasticity of carbon acquisition and WUE to temperature is controlled by the loci that control variation of development, size, growth, and transpiration. A fourth QTL, MSAT2.22, controlled the response of carbon acquisition to specific combinations of watering and temperature irrespective of plant size and development, growth, and transpiration rate, which resulted in size-independent plasticity of WUE. These findings highlight how the strategies to optimize plant performance may differ in response to water deficit and high temperature (or their combination), and how different G × E effects could be targeted to improve plant tolerance to these stresses. PMID:25246443

  19. Multivariate genetic analysis of plant responses to water deficit and high temperature revealed contrasting adaptive strategies

    PubMed Central

    Vasseur, François; Bontpart, Thibaut; Dauzat, Myriam; Granier, Christine; Vile, Denis

    2014-01-01

    How genetic factors control plant performance under stressful environmental conditions is a central question in ecology and for crop breeding. A multivariate framework was developed to examine the genetic architecture of performance-related traits in response to interacting environmental stresses. Ecophysiological and life history traits were quantified in the Arabidopsis thaliana Ler×Cvi mapping population exposed to constant soil water deficit and high air temperature. The plasticity of the genetic variance–covariance matrix (G-matrix) was examined using mixed-effects models after regression into principal components. Quantitative trait locus (QTL) analysis was performed on the predictors of genotype effects and genotype by environment interactions (G×E). Three QTLs previously identified for flowering time had antagonistic G×E effects on carbon acquisition and the other traits (phenology, growth, leaf morphology, and transpiration). This resulted in a size-dependent response of water use efficiency (WUE) to high temperature but not soil water deficit, indicating that most of the plasticity of carbon acquisition and WUE to temperature is controlled by the loci that control variation of development, size, growth, and transpiration. A fourth QTL, MSAT2.22, controlled the response of carbon acquisition to specific combinations of watering and temperature irrespective of plant size and development, growth, and transpiration rate, which resulted in size-independent plasticity of WUE. These findings highlight how the strategies to optimize plant performance may differ in response to water deficit and high temperature (or their combination), and how different G×E effects could be targeted to improve plant tolerance to these stresses. PMID:25246443

  20. Plants

    NSDL National Science Digital Library

    Miss Quinn

    2005-05-02

    Use these links to find out more about plants. This site will help you determine what a plant needs to grow. Michigan's 4-H Children's Garden This site will send you through an adventure where you try to discover if you can grow plants on the moon. Adventures of the agronauts These 2 sites are teacher resource sites on plants. Light Plants and Dark Plants, Wet Plants and Dry Ones The New York Times Daily Lesson Plan: Growing Pains ...

  1. The Rise of Flowering Plants and Land Surface Physics: The Cretaceous and Eocene Were Different

    NASA Astrophysics Data System (ADS)

    Upchurch, G. R.; Feild, T.

    2010-12-01

    The Cretaceous and Eocene have served as the poster children of past greenhouse climates. One difference between the two time periods is that angiosperms (flowering plants) underwent a major diversification and rise to dominance during the mid-Cretaceous to Paleocene. Flowering plants differ from all other living and fossil plants in having significantly higher rates of transpiration and photosynthesis, which in modern leaves correlate with the density of venation (Dv), a feature that can be measured directly from fossils. This increase in Dv, coupled with an increase in the abundance of angiosperms, is thought to have had major impact on the climate system. This is, in part, because transpiration plays an important role in determining the ratio of sensible to latent heat flux from the land surface and in determining precipitation rate in regions such as the equatorial rainforest. Analysis of Dv in fossil leaves indicates two phases of increase in transpiration rate for angiosperms during the Cretaceous-Paleocene. The oldest known angiosperms (Aptian-early Albian) have a low Dv characteristic of extant and fossil ferns and gymnosperms. At this time angiosperms are low-stature plants of minor importance in terms of relative abundance and diversity (<5%). The first phase of Dv increase occurs during the Late Albian to Cenomanian, where average Dv is 40% greater than that of conifers and ferns, and maximum Dv reaches levels characteristic of many trees from the temperate zone. This first phase coincides with the first local dominance of angiosperms, the first occurrence of moderate to large angiosperm trees (up to 1 m in diameter) , and the first common occurrence of angiosperms in the Arctic. The second phase of Dv increase occurs during the Maastrichtian to Paleocene, where average Dv reaches levels characteristic of modern tropical forests and maximum Dv reaches the level found in highly productive modern vegetation. This second phase coincides with the rise to dominance of angiosperms in regional vegetation, a corresponding decline of conifers and ferns, and the modernization of hydraulic architecture in angiosperm wood. The full implications of these changes in land cover have yet to be explored with Earth System models, especially outside the tropics. However, under similar LAI and pCO2, Cretaceous vegetation would have made a greater contribution to global warming than Eocene vegetation through greater sensible heating of the land surface and possibly reduced liquid clouds due to decreased transpiration.

  2. Single high-dose vs. fractionated radiotherapy: Effects on plant growth rates

    PubMed Central

    Guedea, Marc; Castel, Antoni; Arnalte, Marc; Mollera, Alex; Muñoz, Victor; Guedea, Ferran

    2013-01-01

    Aim To evaluate the differential effects of fractionated vs. high-dose radiotherapy on plant growth. Background Interest in hypofractionated radiotherapy has increased substantially in recent years as tumours (especially of the lung, prostate, and liver) can be irradiated with ever greater accuracy due to technological improvements. The effects of low-dose ionizing radiation on plant growth have been studied extensively, yet few studies have investigated the effect of high-dose, hypofractionated radiotherapy on plant growth development. Materials and methods A total of 150 plants from the genus Capsicum annuum were randomized to receive fractionated radiotherapy (5 doses of 10 Gy each), single high-dose (SHD) radiotherapy (single 50 Gy dose), or no radiotherapy (control group). Irradiation was delivered via linear accelerator and all samples were followed daily for 26 days to assess and compare daily growth. Results On day 26, plants in the control, fractionated, and SHD groups had grown to a mean height of 7.55 cm, 4.32 cm, and 2.94 cm, respectively. These differences in overall growth were highly significant (P = 0.005). The SHD group showed the least amount of growth. Conclusions SHD effectively stunts plant growth and development. Despite the evident differences between plant and animal cells, ionizing radiation is believed to work in a similar manner in all biological cells. These findings highlight the need to continue investigating the use of hypofractionated schemes in humans to improve cancer treatment outcomes. PMID:24416565

  3. Effect of low dose gamma irradiation on plant and grain nutrition of wheat

    NASA Astrophysics Data System (ADS)

    Singh, Bhupinder; Datta, Partha Sarathi

    2010-08-01

    We recently reported the use of low dose gamma irradiation to improve plant vigor, grain development and yield attributes of wheat ( Singh and Datta, 2010). Further, we report here the results of a field experiment conducted to assess the effect of gamma irradiation at 0, 0.01, 0.03, 0.05, 0.07 and 0.1 kGy on flag leaf area, stomatal conductance, transpiration and photosynthetic rate and plant and grain nutritional quality. Gamma irradiation improved plant nutrition but did not improve the nutritional quality of grains particularly relating to micronutrients. Grain carotene, a precursor for vitamin A, was higher in irradiated grains. Low grain micronutrients seem to be caused by a limitation in the source to sink nutrient translocation rather than in the nutrient uptake capacity of the plant root.

  4. Thermographic visualization of leaf response in cucumber plants infected with the soil-borne pathogen Fusarium oxysporum f. sp. cucumerinum.

    PubMed

    Wang, Min; Ling, Ning; Dong, Xian; Zhu, Yiyong; Shen, Qirong; Guo, Shiwei

    2012-12-01

    Infection with the soil-borne pathogen Fusarium oxysporum f. sp. cucumerinum (FOC), which causes Fusarium wilt of cucumber plants, might result in changes in plant transpiration and water status within leaves. To monitor leaf response in cucumber infected with FOC, digital infrared thermography (DIT) was employed to detect changes in leaf temperature. During the early stages of FOC infection, stomata closure was induced by ABA in leaves, resulting in a decreased transpiration rate and increased leaf temperature. Subsequently, cell death occurred, accompanied by water loss, resulting in a little decrease in leaf temperature. A negative correlation between transpiration rate and leaf temperature was existed. But leaf temperature exhibited a special pattern with different disease severity on light-dark cycle. Lightly wilted leaves had a higher temperature in light and a lower temperature in dark than did in healthy leaves. We identified that the water loss from wilted leaves was regulated not by stomata but rather by cells damage caused by pathogen infection. Finally, water balance in infected plants became disordered and dead tissue was dehydrated, so leaf temperature increased again. These data suggest that membrane injury caused by FOC infection induces uncontrolled water loss from damaged cells and an imbalance in leaf water status, and ultimately accelerate plant wilting. Combining detection of the temperature response of leaves to light-dark conditions, DIT not only permits noninvasive detection and indirect visualization of the development of the soil-borne disease Fusarium wilt, but also demonstrates certain internal metabolic processes correlative with water status. PMID:23103050

  5. Parameter estimation of a plant uptake model for cyanide: application to hydroponic data.

    PubMed

    Bushey, Joseph T; Small, Mitchell J; Dzombak, David A; Ebbs, Stephen D

    2006-01-01

    A plant uptake model is applied to describe free cyanide and ferrocyanide transport and fate in willow (Salix eriocephala var. Michaux) grown in hydroponics. The model is applied to experimental data to determine best-fit parameter values, their associated uncertainty, and their relative importance to field-scale phytoremediation applications. The fitted model results, using least-squares optimization of the observed log concentrations, indicate that free cyanide volatilization from leaf tissue and free cyanide cell wall adsorption were negligible. The free cyanide maximum uptake rate and assimilate (noncyanide 15N) first-order leaf loss rate were the only coefficients that significantly affected the model goodness of fit and were concurrently sensitive to data uncertainty in the parameter optimization. Saturation kinetics may be applicable for free cyanide uptake into plants, but not for ferrocyanide uptake, which may occur via preferential protein-mediated or inefficient transpiration stream uptake. Within the free cyanide system, the relative magnitudes of the saturation uptake parameters and the demonstration of an active role for plants in uptake relative to transpiration suggest the potential importance of preferential diffusion through the cell membranes as reported in the literature, rather than protein-mediated uptake. The fitted 13-parameter model matched the observed data well except for the predicted stem and leaf tissue assimilate concentrations, which were significantly underestimated, particularly in the free cyanide system. These low predicted values, combined with the slightly underestimated solution free cyanide removal, suggest that noncyanide 15N redistribution in phloem should be considered. PMID:16615307

  6. The influence of plant spacing and rates of nitrogen on the morphology of two rice varieties

    E-print Network

    Stansel, James Wilbert

    1959-01-01

    of the plant. The extant oi the tillering was in inverse proportion to the quantity of seed sown. Parr generalixed that if a plant has a large area from which to obtain its nutrients& it will develop more tillers than a plant with lass area upon which... or the 120 pound levels. Century Patna 231 produced its maximum number cf tillers one week earlier than Bluebonnet 50. This difference in time of tillering was responsible for the interaction between time and variety to be significant at the . 01 level...

  7. Transcriptomics and molecular evolutionary rate analysis of the bladderwort (Utricularia), a carnivorous plant with a minimal genome

    PubMed Central

    2011-01-01

    Background The carnivorous plant Utricularia gibba (bladderwort) is remarkable in having a minute genome, which at ca. 80 megabases is approximately half that of Arabidopsis. Bladderworts show an incredible diversity of forms surrounding a defined theme: tiny, bladder-like suction traps on terrestrial, epiphytic, or aquatic plants with a diversity of unusual vegetative forms. Utricularia plants, which are rootless, are also anomalous in physiological features (respiration and carbon distribution), and highly enhanced molecular evolutionary rates in chloroplast, mitochondrial and nuclear ribosomal sequences. Despite great interest in the genus, no genomic resources exist for Utricularia, and the substitution rate increase has received limited study. Results Here we describe the sequencing and analysis of the Utricularia gibba transcriptome. Three different organs were surveyed, the traps, the vegetative shoot bodies, and the inflorescence stems. We also examined the bladderwort transcriptome under diverse stress conditions. We detail aspects of functional classification, tissue similarity, nitrogen and phosphorus metabolism, respiration, DNA repair, and detoxification of reactive oxygen species (ROS). Long contigs of plastid and mitochondrial genomes, as well as sequences for 100 individual nuclear genes, were compared with those of other plants to better establish information on molecular evolutionary rates. Conclusion The Utricularia transcriptome provides a detailed genomic window into processes occurring in a carnivorous plant. It contains a deep representation of the complex metabolic pathways that characterize a putative minimal plant genome, permitting its use as a source of genomic information to explore the structural, functional, and evolutionary diversity of the genus. Vegetative shoots and traps are the most similar organs by functional classification of their transcriptome, the traps expressing hydrolytic enzymes for prey digestion that were previously thought to be encoded by bacteria. Supporting physiological data, global gene expression analysis shows that traps significantly over-express genes involved in respiration and that phosphate uptake might occur mainly in traps, whereas nitrogen uptake could in part take place in vegetative parts. Expression of DNA repair and ROS detoxification enzymes may be indicative of a response to increased respiration. Finally, evidence from the bladderwort transcriptome, direct measurement of ROS in situ, and cross-species comparisons of organellar genomes and multiple nuclear genes supports the hypothesis that increased nucleotide substitution rates throughout the plant may be due to the mutagenic action of amplified ROS production. PMID:21639913

  8. Rice (Oryza sativa L.) response to clomazone as influenced by rate, soil type, and planting date

    E-print Network

    O'Barr, John Houston

    2006-08-16

    not accurately estimate the amount of herbicide available for plant uptake. The concentration of herbicide in soil water is primarily dependent on dissolution into the liquid phase, adsorption on the soil components, leaching, and degradation 5... above -1500 kPa water potential is assumed to be available for plant uptake (Kobayahi et al. 1994). Soil moisture variations can affect herbicide availability (Dao and Lavy 1978; Green and Obien 1969; Moyer 1987). In an upland soil (non...

  9. Seasonal photosynthetic gas exchange and water-use efficiency in a constitutive CAM plant, the giant saguaro cactus (Carnegiea gigantea).

    PubMed

    Bronson, Dustin R; English, Nathan B; Dettman, David L; Williams, David G

    2011-11-01

    Crassulacean acid metabolism (CAM) and the capacity to store large quantities of water are thought to confer high water use efficiency (WUE) and survival of succulent plants in warm desert environments. Yet the highly variable precipitation, temperature and humidity conditions in these environments likely have unique impacts on underlying processes regulating photosynthetic gas exchange and WUE, limiting our ability to predict growth and survival responses of desert CAM plants to climate change. We monitored net CO(2) assimilation (A(net)), stomatal conductance (g(s)), and transpiration (E) rates periodically over 2 years in a natural population of the giant columnar cactus Carnegiea gigantea (saguaro) near Tucson, Arizona USA to investigate environmental and physiological controls over carbon gain and water loss in this ecologically important plant. We hypothesized that seasonal changes in daily integrated water use efficiency (WUE(day)) in this constitutive CAM species would be driven largely by stomatal regulation of nighttime transpiration and CO(2) uptake responding to shifts in nighttime air temperature and humidity. The lowest WUE(day) occurred during time periods with extreme high and low air vapor pressure deficit (D(a)). The diurnal with the highest D(a) had low WUE(day) due to minimal net carbon gain across the 24 h period. Low WUE(day) was also observed under conditions of low D(a); however, it was due to significant transpiration losses. Gas exchange measurements on potted saguaro plants exposed to experimental changes in D(a) confirmed the relationship between D(a) and g(s). Our results suggest that climatic changes involving shifts in air temperature and humidity will have large impacts on the water and carbon economy of the giant saguaro and potentially other succulent CAM plants of warm desert environments. PMID:21822726

  10. Effect of MHD and Injection through one side of a long vertical channel embedded in porous medium with transpiration cooling

    NASA Astrophysics Data System (ADS)

    Govardhan, K.; Kaladhar, K.; Nagaraju, G.; Balaswamy, B.

    2014-12-01

    This paper examines the effect of MHD, and injection through one side of a long vertical channel embedded in porous medium with transpiration cooling. The governing nonlinear partial differential equations have been transformed by similarity transformation into a set of ordinary differential equations, which are solved numerically by Adam-moultan Predictor-Corrector method with Newton-Raphson Method for missing initial conditions. Proflles of dimensionless velocity, temperature and concentration are shown graphically for different parameters entering into the analysis. Also the effects of the pertinent parameters on the heat transfer rates are tabulated. An analysis of the results obtained shows that the flow field is influenced appreciably by emerging parameters of the present study.

  11. The effect of root temperature on the induction of nitrate reductase activities and nitrogen uptake rates in arctic plant species

    Microsoft Academic Search

    Owen K. Atkin; W. Raymond Cummins

    1994-01-01

    We investigated whether six arctic plant species have the potential to induce nitrate reductase (NR) activity when exposed to NO3--nitrogen under controlled environment conditions, using an in vivo assay that uses the rate of NO2--accumulation to estimate potential NR activity. We also assessed the effect of low root temperatures on NR activity, growth and nitrogen uptake (using 15N applications) in

  12. A quantitative application of the thermoelectric method for measuring water uptake by cotton plants

    E-print Network

    Naghshineh-Pour, Bahman

    1965-01-01

    . I am also thankful for the techr. ical assistance of Mr. M. Homayoun during the execution of the experiment. 111 To Yvonne TABLE OF CONTENTS Page I. INTRODUCTION II. LITERATURE REVIEW Plant-Water Relations Transpiration Measurements Soil...

  13. Advanced regulatory control and coordinated plant-wide control strategies for IGCC targeted towards improving power ramp-rates

    SciTech Connect

    Mahapatra, P.; Zitney, S.

    2012-01-01

    As part of ongoing R&D activities at the National Energy Technology Laboratory's (NETL) Advanced Virtual Energy Simulation Training & Research (AVESTAR™) Center, this paper highlights strategies for enhancing low-level regulatory control and system-wide coordinated control strategies implemented in a high-fidelity dynamic simulator for an Integrated Gasification Combined Cycle (IGCC) power plant with carbon capture. The underlying IGCC plant dynamic model contains 20 major process areas, each of which is tightly integrated with the rest of the power plant, making individual functionally-independent processes prone to routine disturbances. Single-loop feedback control although adequate to meet the primary control objective for most processes, does not take into account in advance the effect of these disturbances, making the entire power plant undergo large offshoots and/or oscillations before the feedback action has an opportunity to impact control performance. In this paper, controller enhancements ranging from retuning feedback control loops, multiplicative feed-forward control and other control techniques such as split-range control, feedback trim and dynamic compensation, applicable on various subsections of the integrated IGCC plant, have been highlighted and improvements in control responses have been given. Compared to using classical feedback-based control structure, the enhanced IGCC regulatory control architecture reduces plant settling time and peak offshoots, achieves faster disturbance rejection, and promotes higher power ramp-rates. In addition, improvements in IGCC coordinated plant-wide control strategies for “Gasifier-Lead”, “GT-Lead” and “Plantwide” operation modes have been proposed and their responses compared. The paper is concluded with a brief discussion on the potential IGCC controller improvements resulting from using advanced process control, including model predictive control (MPC), as a supervisory control layer.

  14. Does hydraulic lift or nighttime transpiration facilitate nitrogen acquistion?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    It has been proposed that plant species that hydraulically lift water to dry shallow soil layers should have improved nutrient relations. Yet, this idea has not been adequately tested. We choose ten Sarcobatus vermiculatus plants with different magnitudes of hydraulic lift to examine the hypothesis...

  15. Mechanism of Methane Transport from the Rhizosphere to the Atmosphere through Rice Plants 1

    PubMed Central

    Nouchi, Isamu; Mariko, Shigeru; Aoki, Kazuyuki

    1990-01-01

    To clarify the mechanisms of methane transport from the rhizosphere into the atmosphere through rice plants (Oryza sativa L.), the methane emission rate was measured from a shoot whose roots had been kept in a culture solution with a high methane concentration or exposed to methane gas in the gas phase by using a cylindrical chamber. No clear correlation was observed between change in the transpiration rate and that in the methane emission rate. Methane was mostly released from the culm, which is an aggregation of leaf sheaths, but not from the leaf blade. Micropores which are different from stomata were newly found at the abaxial epidermis of the leaf sheath by scanning electron microscopy. The measured methane emission rate was much higher than the calculated methane emission rate that would result from transpiration and the methane concentration in the culture solution. Rice roots could absorb methane gas in the gas phase without water uptake. These results suggest that methane dissolved in the soil water surrounding the roots diffuses into the cell-wall water of the root cells, gasifies in the root cortex, and then is mostly released through the micropores in the leaf sheaths. Images Figure 7 PMID:16667719

  16. Mechanism of methane transport from the rhizosphere to the atmosphere through rice plants

    SciTech Connect

    Nouchi, Isamu (National Institute of Agro-Environmental Sciences, Ibaraki (Japan)); Mariko, Shigeru (Tokyo Metropolitan Univ. (Japan)); Aoki, Kazuyuki (Tokyo Metropolitan Research Institute for Environmental Protection (Japan))

    1990-09-01

    To clarify the mechanisms of methane transport from the rhizosphere into the atmosphere through rice plants (Oryza sativa L.), the methane emission rate was measured from a shoot whose roots had been kept in a culture solution with a high methane concentration or exposed to methane gas in the gas phase by using a cylindrical chamber. No clear correlation was observed between change in the transpiration rate and that in the methane emission rate. Methane was mostly released from the culm, which is an aggregation of leaf sheaths, but not from the leaf blade. Micropores which are different from stomata were newly found at the abaxial epidermis of the leaf sheath by scanning electron microscopy. The measured methane emission rate was much higher than the calculated methane emission rate that would result from transpiration and the methane concentration in the culture solution. Rice roots absorb methane gas in the gas phase without water uptake. These results suggest that methane dissolved in the soil water surrounding the roots diffuses into the cell-wall water of the root cells, gasifies in the root cortex, and then is mostly released through the micropores in the leaf sheaths.

  17. The metabolic signature related to high plant growth rate in Arabidopsis thaliana

    PubMed Central

    Meyer, Rhonda C.; Steinfath, Matthias; Lisec, Jan; Becher, Martina; Witucka-Wall, Hanna; Törjék, Ottó; Fiehn, Oliver; Eckardt, Änne; Willmitzer, Lothar; Selbig, Joachim; Altmann, Thomas

    2007-01-01

    The decline of available fossil fuel reserves has triggered world-wide efforts to develop alternative energy sources based on plant biomass. Detailed knowledge of the relations of metabolism and biomass accumulation can be expected to yield powerful novel tools to accelerate and enhance energy plant breeding programs. We used metabolic profiling in the model Arabidopsis to study the relation between biomass and metabolic composition using a recombinant inbred line (RIL) population. A highly significant canonical correlation (0.73) was observed, revealing a close link between biomass and a specific combination of metabolites. Dividing the entire data set into training and test sets resulted in a median correlation between predicted and true biomass of 0.58. The demonstrated high predictive power of metabolic composition for biomass features this composite measure as an excellent biomarker and opens new opportunities to enhance plant breeding specifically in the context of renewable resources. PMID:17360597

  18. Comparing the effectiveness of heat rate improvements in different coal-fired power plants utilizing carbon dioxide capture

    NASA Astrophysics Data System (ADS)

    Walsh, Martin Jeremy

    New Congressional legislation may soon require coal-fired power generators to pay for their CO2 emissions and capture a minimum level of their CO2 output. Aminebased CO2 capture systems offer plants the most technically proven and commercially feasible option for CO2 capture at this time. However, these systems require a large amount of heat and power to operate. As a result, amine-based CO2 capture systems significantly reduce the net power of any units in which they are installed. The Energy Research Center has compiled a list of heat rate improvements that plant operators may implement before installing a CO2 capture system. The goal of these improvements is to upgrade the performance of existing units and partially offset the negative effects of adding a CO2 capture system. Analyses were performed in Aspen Plus to determine the effectiveness of these heat rate improvements in preserving the net power and net unit heat rate (NUHR) of four different power generator units. For the units firing high-moisture sub-bituminous coal, the heat rate improvements reduced NUHR by an average of 13.69% across a CO 2 capture level range of 50% to 90%. For the units firing bituminous coal across the same CO2 capture range, the heat rate improvements reduced NUHR by an average of 12.30%. Regardless of the units' coal or steam turbine cycle type, the heat rate improvements preserved 9.7% to 11.0% of each unit's net power across the same CO2 capture range. In general, the heat rate improvements were found to be most effective in improving the performance of units firing high-moisture sub-bituminous. The effect of the CO2 capture system on these units and the reasons for the improvements' greater effectiveness in them are described in this thesis.

  19. A study of the distribution and production rates of ethylene within the cotton plant

    E-print Network

    McAfee, James A

    1970-01-01

    : Drs. P. W. Korgan, H. E, Joham? and E. C. E'olt, whose assistar. ce helped make the comple- tion of :his work possible. I would especially like to thank Dz. . P. W. Norgan for hi; frie?zdshio, guidaz?ce, and svppoz t through~ the course o my... the importance of e+hylene to the field of plant hormone research. Discovery of Ethylene as a Plant Growth Regulator As early ss +he 1860's, there were several reports of plani, damage due to toxic gases. Wiesner, in 1787, nci-'ce some unusual cuzvatures...

  20. A whole-plant cuvette system to measure short-term responses of conifer seedlings to environmental change.

    PubMed

    Livingston, N. J.; Davies, G. J.; Eby, B. M.; Filek, G.; Fuchs, E. E.; Pepin, S.; Percy, R. E.

    1994-01-01

    A computer-controlled whole-plant cuvette system is described that allows precise and independent control of temperature (+/- 0.05 degrees C), vapor pressure (+/- 0.02 kPa), CO(2) concentration (+/- 2 micro mol mol(-1)) and photosynthetic photon flux density (+/- 5 micro mol m(-2) s(-1)), and allows the continuous measurement of net photosynthesis and transpiration rates. Vapor pressure is controlled by circulating chamber air through a CaSO(4) desiccant column supported on a digital balance. Transpiration rate is calculated from the change in desiccant mass with time. Photosynthesis rate is measured by integrating the output of a mass flow controller used to inject CO(2) into the chamber to compensate for that assimilated by the plant. The control system can be driven by set points that can be varied, for example, as a function of time, or held constant. We were able to simulate weather data obtained from climate stations and accurately follow, in real time, the output of sensors measuring outside conditions. Experiments on well-watered one- and two-year-old nursery-raised western red cedar (Thuja plicata Donn.) and white spruce (Picea glauca (Moench) Voss) seedlings showed that if the mean daily temperature was increased from 20 to 22 degrees C with vapor pressure remaining constant at 1 kPa, CO(2) concentrations must almost double to compensate for the decrease in net photosynthesis rate. PMID:14967646