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1

Transpiration rates of rice plants treated with Trichoderma spp.  

NASA Astrophysics Data System (ADS)

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.

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

2014-09-01

2

Plant Cycles: Photosynthesis & Transpiration  

NSDL National Science Digital Library

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.

Integrated Teaching And Learning Program

3

Effect of transpiration rate on internal plant resistance to water flow  

E-print Network

of the literatures an Ohm's law analogy seems applicable in the liquid phase of water transpor t in plants Exper iments to verify this views that the internal plant resistance to water flow in southern peas (Vigna sinensis L ~ Endl. var ~ Burgundy) does... AND DISCUSSION Transpiration Rate and Internal Plant Resistance for Southern Peas Leaf Diffusion Resistances. Leaf Temperatures and Stem Diameter ~ Total Resistance to Vapor Diffusion from Leaf to Air ~ ~ Engineering Application of Results V SUMMARY...

Hailey, James Lester

2012-06-07

4

Just Breathe Green: Measuring Transpiration Rates  

NSDL National Science Digital Library

Through multi-trial experiments, students are able to see and measure something that is otherwise invisible to themâseeing 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.

Water Awareness Research and Education (WARE) Research Experience for Teachers (RET),

5

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

Microsoft Academic Search

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

A. Clyde Hill; Niel Littlefield

1969-01-01

6

Field experiment on transpiration from isolated urban plants  

Microsoft Academic Search

The effect of pot plant density on plant transpiration rate was examined in a series of field experiments. Three spatial densities were created using 203 nearly homogeneous pot plants; the ratios of plant separation to plant height were 0Ð25, 0Ð5, and 3 for the 'high,' 'medium,' and 'low' groups respectively. The daily transpiration rate of 55 pot plants was measured

Aya Hagishima; Ken-Ich Narita; Jun Tanimoto

2007-01-01

7

Plant transpiration distillation of water  

SciTech Connect

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.

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

1986-01-01

8

Daily transpiration rates of woody species on drying soil.  

PubMed

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

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

2005-11-01

9

Zinc uptake by young wheat plants under two transpiration regimes  

SciTech Connect

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.

Grifferty, A.; Barrington, S.

2000-04-01

10

Residual transpiration rate, epicuticular wax load and leaf colour of pea plants in drought conditions. Influence on harvest index and canopy temperature  

Microsoft Academic Search

Residual transpiration rates, epicuticular wax loads and leaf colours of 20 cultivars of pea (commercial varieties and bred, improved lines) were studied. The residual transpiration rate varied between genotypes from 0.77 to 1.82 mg m?2 s?1, while wax content varied between 0.19 and 0.41 g m?2. Leaf colour varied on the Munsell colour saturation scale between 4 and 8. No

Francisco J. Sánchez; Mar??a Manzanares; Eusebio F. de Andrés; José Luis Tenorio; Luis Ayerbe

2001-01-01

11

Characterizing photosynthesis and transpiration of plant communities in controlled environments  

NASA Technical Reports Server (NTRS)

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.

Monje, O.; Bugbee, B.

1996-01-01

12

Measuring Transpiration to Regulate Winter Irrigation Rates  

SciTech Connect

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.

Samuelson, Lisa [Auburn University] [Auburn University

2006-11-08

13

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

ERIC Educational Resources Information Center

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)

Seligmann, Peter F.; Thompson, Steven R.

1989-01-01

14

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

E-print Network

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

Rubin, Yoram

15

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

E-print Network

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

Soatto, Stefano

16

Root water compensation sustains transpiration rates in an Australian woodland  

NASA Astrophysics Data System (ADS)

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.

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

2014-12-01

17

Transpiration in seven plant species colonizing a fishpond shore  

Microsoft Academic Search

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

J. Kv?t

1975-01-01

18

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

E-print Network

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

Paris-Sud XI, Université de

19

Sapwood Area as a Scaling Factor for Transpiration Rates  

NASA Astrophysics Data System (ADS)

The process of transpiration in forested areas is a function of the spatial and temporal variations in vegetation structural attributes. Therefore, it is possible to scale up the transpiration of a single tree to multi-tree scales using vegetation structural patterns. The main goal of this research is to generate, apply and verify a procedure for scaling up the process of transpiration in forested areas over a range of three spatial scales {tree, plot, and catchment} and within daily/monthly/seasonal scale. In order to accomplish this goal, it is necessary to identify vegetation characteristics that are appropriate scaling factors. Sapwood is the active part of the xylem for water and nutrients transport towards the leaves. Thus, sapwood area is an effective scaling factor for transpiration rates from a single point in a tree to the whole tree. Also, sapwood area establishes the limit on the quantity of foliage for a tree, and thus its vigour. The study area for this research is in the Montane eco-region of southern Alberta which includes species of Jack Pine, Lodgepole Pine, Black Spruce and Trembling Aspen. Sapwood area is estimated as the cross-sectional area of the outer vascular tissue responsible for transporting water in the acropetal way. As sapwood depth does not form a perfect ring around the tree trunk, it was measured in the four cardinal compass points and then an average value for the estimation of sapwood area was obtained. Two methods were used to estimate sapwood depth: dye infusion and microscopic identification of sapwood tissue. While the former method is widely used, it was deemed unsuccessful in our study area due to damage that vessels/tracheids suffered during the coring/extraction process. The latter is a laborious method, due to the detailed scale at which the analysis is performed. However, it assures accuracies of roughly 98%\\ for determining sapwood depth. A more detailed comparison of both methods is presented. Results demonstrate a high correlation between the depth of sapwood area and the aspect, where the deepest sapwood at the breast height was found in the North and East faces of the sampled boreal trees. Other results of interest for scaling transpiration are presented, such as correlations between sapwood depth and diameter at breast height, sapwood depth and basal area, sapwood depth and species type.

Quinonez-Pinon, R.; Valeo, C.

2004-05-01

20

Transpiration response of boreal forest plants to permafrost thaw  

NASA Astrophysics Data System (ADS)

Shifts in the rate and patterns of evapotranspiration with permafrost thaw, vegetation change, and altered climatic conditions are unknown in boreal systems. Specifically, the response of transpiration is not well understood but critical to quantify given its non-linear response to climate. We asked: what is the effect of permafrost thaw on the transpiration dynamics of sub-Arctic boreal plants? We utilized a Bayesian analysis approach to quantify the responses of plants located in areas with and without stable permafrost to current and antecedent vapor pressure deficit, soil moisture, soil temperature, and the prior year's soil temperature. We measured stomatal conductance (gs) on six species of plants over two summers. For the analysis, the plants were grouped into three functional types: deciduous shrubs, evergreen sub-shrubs, and black spruce trees. The model we constructed includes a VPD (current and antecedent) sensitivity term modeled as a function of soil moisture (current and antecedent), and a "base" gs term modeled as a function of current soil temperature (at different depths), thaw depth, and the prior growing season's soil temperature (for each month, May - September). Current VPD was more important early in the growing season, but antecedent VPD was more important later in the growing season. The memory of gs for antecedent VPD was ~ three weeks in the past. The daily trends were less resolved for the site with degrading permafrost. Deeper thaw resulted in higher sensitivity to VPD and higher gs, particularly at the site with stable permafrost. Deciduous shrubs showed the strongest effect. At the site with thawing permafrost, soil water positively affected the sensitivity of gs to VPD for the deciduous shrubs but had a negative effect on black spruce. Current soil moisture was important early in the growing season but antecedent moisture was important at the end. The site with thawing permafrost had a longer memory (two weeks) for antecedent moisture than the site with stable permafrost. In terms of the "base" gs rate, current soil temperature positively affects gs in the deciduous functional types. The prior year's soil temperature positively affected the black spruce base rate at the end of the season, but negatively affected the evergreen sub-shrubs at the beginning of the season. Soil temperature the prior year's May was most important at the site with thawing permafrost, but May and June were important for the site with stable permafrost. These preliminary results suggest that (1) we must account for within-season and the prior year's antecedent conditions when quantifying the effects of permafrost thaw on plant function, and (2) permafrost thaw changes how boreal forest plant species respond to climate and soil conditions. Next, we must quantify the mechanisms of the antecedent response to determine thresholds in thaw that could result in shifts in species composition.

Cable, J.; Ogle, K.; Welker, J. M.

2011-12-01

21

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

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

Nacional de San Luis, Universidad

22

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

SciTech Connect

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.

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

1992-12-31

23

Predicting the effects of gas diffusivity on photosynthesis and transpiration of plants grown under hypobaria  

NASA Astrophysics Data System (ADS)

As part of a Bio-regenerative Life Support System (BLSS) for long-term space missions, plants will likely be grown at reduced pressure. This low pressure will minimize structural requirements for growth chambers on missions to the Moon or Mars. However, at reduced pressures the diffusivity of gases increases. This will affect the rates at which CO2 is assimilated and water is transpired through stomata. To understand quantitatively the possible effects of reduced pressure on plant growth, CO2 and H2O transport were calculated for atmospheres of various total pressures (101, 66, 33, 22, 11 kPa) and CO2 concentrations (0.04, 0.1 and 0.18 kPa). The diffusivity of a gas is inversely proportional to total pressure and shows dramatic increases at pressures below 33 kPa (1/3 atm). A mathematical relationship based on the principle of thermodynamics was applied to low pressure conditions and can be used for calculating the transpiration and photosynthesis of plants grown in hypobaria. At 33 kPa total pressure, the stomatal conductance increases by a factor of three with the boundary layer conductance increasing by a factor of ˜1.7, since the leaf conductance is a function of both stomatal and the boundary layer conductance, the overall conductance will increase resulting in significantly higher levels of transpiration as the pressure drops. The conductance of gases is also regulated by stomatal aperture in an inverse relationship. The higher CO2 concentration inside the leaf air space during low pressure treatments may result in higher CO2 assimilation and partial stomata closure, resulting in a decrease in transpiration rate. The results of this analysis offer guidelines for experiments in pressure and high CO2 environments to establish ideal conditions for minimizing transpiration and maximizing the plant biomass yield in BLSS.

Gohil, Hemant L.; Correll, Melanie J.; Sinclair, Thomas

2011-01-01

24

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

SciTech Connect

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.

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

1994-12-31

25

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

Microsoft Academic Search

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,

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

2007-01-01

26

A Transpiration Experiment Requiring Critical Thinking Skills.  

ERIC Educational Resources Information Center

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)

Ford, Rosemary H.

1998-01-01

27

Nighttime transpiration in woody plants from contrasting ecosystems.  

PubMed

It is commonly assumed that transpiration does not occur at night because leaf stomata are closed in the dark. We tested this assumption across a diversity of ecosystems and woody plant species by various methods to explore the circumstances when this assumption is false. Our primary goals were: (1) to evaluate the nature and magnitude of nighttime transpiration, E(n), or stomatal conductance, g(n); and (2) to seek potential generalizations about where and when it occurs. Sap-flow, porometry and stable isotope tracer measurements were made on 18 tree and eight shrub species from seven ecosystem types. Coupled with environmental data, our findings revealed that most of these species transpired at night. For some species and circumstances, nighttime leaf water loss constituted a significant fraction of total daily water use. Our evidence shows that E(n) or g(n) can occur in all but one shrub species across the systems we investigated. However, under conditions of high nighttime evaporative demand or low soil water availability, stomata were closed and E(n) or g(n) approached zero in eleven tree and seven shrub species. When soil water was available, E(n) or g(n) was measurable in these same species demonstrating plasticity for E(n) or g(n). We detected E(n) or g(n) in both trees and shrubs, and values were highest in plants from sites with higher soil water contents and in plants from ecosystems that were less prone to atmospheric or soil water deficits. Irrespective of plant or ecosystem type, many species showed E(n) or g(n) when soil water deficits were slight or non-existent, or immediately after rainfall events that followed a period of soil water deficit. The strongest relationship was between E(n) or g(n) and warm, low humidity and (or) windy (> 0.8 m s(-1)) nights when the vapor pressure deficit remained high (> 0.2 kPa in wet sites, > 0.7 kPa in dry sites). Why E(n) or g(n) occurs likely varies with species and ecosystem type; however, our data support four plausible explanations: (1) it may facilitate carbon fixation earlier in the day because stomata are already open; (2) it may enhance nutrient supply to distal parts of the crown when these nutrients are most available (in wet soils) and transport is rapid; (3) it may allow for the delivery of dissolved O(2) via the parenchyma to woody tissue sinks; or (4) it may occur simply because of leaky cuticles in older leaves or when stomata cannot close fully because of obstructions from stomatal (waxy) plugs, leaf endophytes or asymmetrical guard cells (all non-adaptive reasons). We discuss the methodological, ecophysiological, and theoretical implications of the occurrence of E(n) or g(n) for investigations at a variety of scales. PMID:17241998

Dawson, Todd E; Burgess, Stephen S O; Tu, Kevin P; Oliveira, Rafael S; Santiago, Louis S; Fisher, Joshua B; Simonin, Kevin A; Ambrose, Anthony R

2007-04-01

28

NOTE / NOTE Transpiration-dependent passive silica  

E-print Network

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

Kitajima, Kaoru

29

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

E-print Network

. To determine the transpiration rate a volume of soil around the test trees was instrumented with neutron access tubes. Soil moisture depletion was measured weekly. A soil water balance was conducted equating evapotranspiration to the sum of the change...

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.

30

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

E-print Network

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...

Rodrigue, Paul Bryan

2012-06-07

31

Original article Growth dynamics, transpiration and water-use  

E-print Network

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

Paris-Sud XI, Université de

32

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

E-print Network

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

Holbrook, N. Michele

33

A microfluidic pump/valve inspired by xylem embolism and transpiration in plants.  

PubMed

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

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

2012-01-01

34

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

PubMed Central

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

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

2012-01-01

35

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

E-print Network

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

Teskey, Robert O.

36

[Photosynthetic rate, transpiration rate, and water use efficiency of cotton canopy in oasis edge of Linze].  

PubMed

The measurement system of Li-8100 carbon flux and the modified assimilation chamber were used to study the photosynthetic characteristics of cotton (Gossypium hirsutum L.) canopy in the oasis edge region in middle reach of Heihe River Basin, mid Hexi Corridor of Gansu. At the experimental site, soil respiration and evaporation rates were significantly higher in late June than in early August, and the diurnal variation of canopy photosynthetic rate showed single-peak type. The photosynthetic rate was significantly higher (P < 0.01) in late June than in early August, with the daily average value being (43.11 +/- 1.26) micromol CO2 x m(-2) x s(-1) and (24.53 +/- 0.60) micromol CO2 x m(-2) x s(-1), respectively. The diurnal variation of canopy transpiration rate also presented single-peak type, with the daily average value in late June and early August being (3.10 +/- 0.34) mmol H2O x m(-2) x s(-1) and (1.60 +/- 0.26) mmol H2O x m(-2) x s(-1), respectively, and differed significantly (P < 0.01). The daily average value of canopy water use efficiency in late June and early August was (15.67 +/- 1.77) mmol CO2 x mol(-1) H2O and (23.08 +/- 5.54) mmol CO2 x mol(-1) H2O, respectively, but the difference was not significant (P > 0.05). Both in late June and in early August, the canopy photosynthetic rate was positively correlated with air temperature, PAR, and soil moisture content, suggesting that there was no midday depression of photosynthesis in the two periods. In August, the canopy photosynthetic rate and transpiration rate decreased significantly, because of the lower soil moisture content and leaf senescence, but the canopy water use efficiency had no significant decrease. PMID:20873616

Xie, Ting-Ting; Su, Pei-Xi; Gao, Song

2010-06-01

37

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

NASA Technical Reports Server (NTRS)

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.

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

1992-01-01

38

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

E-print Network

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

Jackson, Robert B.

39

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

Microsoft Academic Search

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

R. W. Downes

1969-01-01

40

Photosynthesis, transpiration, leaf temperature, and stomatal activity of cotton plants under varying water potentials  

Microsoft Academic Search

Cotton plants were grown in a growth room under incident radiation levels of 65, 35, and 17 Langleys per hour to determine the effects of vapor pressure deficits (VPD's) of 2, 9, and 17 mm Hg at high soil water potential, and the effects of decreasing soil water potential and reirrigation on transpiration, leaf temperature, stomatal activity, photosynthesis, and respiration

J. E. Jr. Pallas; B. E. Michel; D. G. Harris

1967-01-01

41

Improved thermal method of continual recording the transpiration flow rate dynamics  

Microsoft Academic Search

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

J. Ktj?era; J. ?ermák; M. Penka

1977-01-01

42

Applicability of high rate transpiration system for treatment of biologically treated distillery effluent.  

PubMed

The biologically treated distillery effluent (BTDE) contains intense colour, high total dissolved solids (TDS), chemical oxygen demand (COD) and biochemical oxygen demand (BOD). These properties even after primary, secondary and tertiary treatments contain high concentrations of TDS, COD and BOD. The paper highlights the safe disposal and treatment of BTDE on land through High Rate Transpiration System (HRTS). HRTS is a zero discharge, low cost, high-tech method for improving the quality of BTDE for potential reuse. The experiments conducted at bench and pilot scale showed that HRTS having coconut husk as a bedding material could successfully treat the BTDE with a hydraulic load of 200 m3 ha(-1) day(-1) having BOD of 100 mg l(-1) and 500 m3 ha(-1) day(-1) having BOD of 500 mg l(-1) with average COD load of 0.686 and 2.88 ton ha(-1) day(-1) during the post and pre monsoon periods respectively. There was no significant increase in the organic carbon of the soil irrigated with BTDE. The concentrations of various pollutants analyzed in the leachate were within the prescribed limit for the drinking water sources. The colour removal was 99 to 100% and BOD and COD were possible to treat with optimum hydraulic loading of BTDE through HRTS planted with Dendrocalamus strictus. PMID:17882528

Singh, S K; Juwarkar, Asha A; Pandey, R A; Chakrabarti, T

2008-06-01

43

A Laboratory Exercise to Assess Transpiration.  

ERIC Educational Resources Information Center

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)

Schrock, Gould F.

1982-01-01

44

Transpiration rates and acclimation to water and temperature of the tropical woodlice, Porcellionides pruinosus Brandt and Porcellio laevis Latreille  

Microsoft Academic Search

The transpiration rates and acclimation to water and temperature ofPorcellionides pruinosus Brandt andPorcellio laevis Latreille, the common terrestrial isopods occurring in and around Trivandrum, India, were studied. Transpiration rates in\\u000a different temperatures (24 to 50°C) were higher in both the species during the first 15 minutes’ exposure when compared to\\u000a 1-hour duration. Previous acclimation to different humidity and temperature conditions

G Achuthan Nair; N Balakrishnan Nair

1985-01-01

45

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

Microsoft Academic Search

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.

H. G. Koritz; F. W. Went

1953-01-01

46

The Arabidopsis gibberellin methyl transferase 1 suppresses gibberellin activity, reduces whole-plant transpiration and promotes drought tolerance in transgenic tomato.  

PubMed

Previous studies have shown that reduced gibberellin (GA) level or signal promotes plant tolerance to environmental stresses, including drought, but the underlying mechanism is not yet clear. Here we studied the effects of reduced levels of active GAs on tomato (Solanum lycopersicum) plant tolerance to drought as well as the mechanism responsible for these effects. To reduce the levels of active GAs, we generated transgenic tomato overexpressing the Arabidopsis thaliana GA METHYL TRANSFERASE 1 (AtGAMT1) gene. AtGAMT1 encodes an enzyme that catalyses the methylation of active GAs to generate inactive GA methyl esters. Tomato plants overexpressing AtGAMT1 exhibited typical GA-deficiency phenotypes and increased tolerance to drought stress. GA application to the transgenic plants restored normal growth and sensitivity to drought. The transgenic plants maintained high leaf water status under drought conditions, because of reduced whole-plant transpiration. The reduced transpiration can be attributed to reduced stomatal conductance. GAMT1 overexpression inhibited the expansion of leaf-epidermal cells, leading to the formation of smaller stomata with reduced stomatal pores. It is possible that under drought conditions, plants with reduced GA activity and therefore, reduced transpiration, will suffer less from leaf desiccation, thereby maintaining higher capabilities and recovery rates. PMID:23668385

Nir, Ido; Moshelion, Menachem; Weiss, David

2014-01-01

47

Reduction of Transpiration  

Microsoft Academic Search

The monomolecular film technique for reducing evaporation from water surfaces has been applied to the problem of transpiration from plants. Hybrid corn grown in soil en- riched by various amounts of fatty alcohols such as hexadecanol has required up to 40 per cent less water during its growth than control plants. It is theorized that some of the transpiration from

W. J. Roberts

1961-01-01

48

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

E-print Network

(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

Ejiri, Shinji

49

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

NASA Astrophysics Data System (ADS)

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.

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

2013-06-01

50

Assimilation and transpiration capabilities of rhyniophytic plants from the Lower Devonian and their implications for paleoatmospheric CO 2 concentration  

Microsoft Academic Search

The characteristic basic construction of early land plants with an upright posture is represented by a simple leaf- and rootless axis system with a central conducting bundle (‘rhyniophytic habit’). Variations of this simple architectural principle in different early land plant taxa probably reflect different ecophysiological requirements. In this contribution, the assimilation and transpiration of three different Rhynie Chert taxa (Pragian,

Anita Roth-Nebelsick; Wilfried Konrad

2003-01-01

51

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

PubMed

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

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

2014-01-01

52

Overexpression of Rice NAC Gene SNAC1 Improves Drought and Salt Tolerance by Enhancing Root Development and Reducing Transpiration Rate in Transgenic Cotton  

PubMed Central

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

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

2014-01-01

53

Photosynthesis, transpiration and water use efficiencies of a plant canopy and plant leaves under restricted air current conditions  

NASA Astrophysics Data System (ADS)

A fundamental study was conducted to obtain the knowledge for culturing plants and exchanging gases with plants under restricted air circulation conditions in space agriculture. The effects of air velocities less than 1.3 m s-1 on net photosynthetic rates (Pn), transpiration rates (Tr) and Pn/Tr, water use efficiencies (WUE), of a canopy of cucumber seedlings and of single leaves of cucumber, sweet potato and barley were assessed with assimilation chamber methods in ground based experiments. The cucumber seedling canopy, which had a LAI of 1.4 and height of 0.1 m, was set in a wind tunnel installed in a plant canopy assimilation chamber. Each of the attached single leaves was set in a leaf assimilation chamber. The Pn and Tr of the plant canopy increased to 1.2 and 2.8 times, respectively, and WUE decreased to 0.4 times with increasing the air velocity from 0.02 to 1.3 m s-1. The Pn and Tr of the single leaves of all the species increased by 1.3-1.7 and 1.9-2.2 times, respectively, and WUE decreased to 0.6-0.8 times as the air velocity increased from 0.05 to 0.8 m s-1. The effect of air velocity was more significant on Tr than on Pn and thus WUE decreased with increasing air velocity in both the plant canopy and the individual leaves. The leaf boundary layer resistance was approximately proportional to the minus 1/3 power of the air velocity. Stomatal resistance was almost constant during the experiment. The CO2 concentrations in the sub-stomatal cavity in leaves of cucumber, sweet potato and barley, respectively, were 43, 31 and 58 mmol mol-1 lower at the air velocity of 0.05 m s-1 than at the air velocity of 0.8 m s-1, while the water vapor pressure in the sub-stomatal cavity was constant. We concluded that the change in the CO2 concentration in the sub-stomatal cavity was a cause of the different effect of the air velocity on Pn and Tr, and thus on WUE. The phenomenon will be more remarkable under restricted air convection conditions at lower gravity in space.

Kitaya, Yoshiaki; Shibuya, Toshio; Tsuruyama, Joshin

54

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

Microsoft Academic Search

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.

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

1999-01-01

55

Ecohydrology of groundwater-dependent ecosystems: a stochastic framework for plant transpiration  

NASA Astrophysics Data System (ADS)

Groundwater-dependent ecosystems are found in areas with a shallow water table, where the groundwater plays a key role on the ecosystem functions. In these areas, the water table depth, the capillary fluxes, and the soil moisture content exert a major control on most ecohydrologic processes, such as infiltration, surface runoff, aquifer recharge, land-atmosphere feedbacks, vegetation dynamics, nutrient cycling, and pollutant transport. Understanding and modeling the soil water balance and its relationships with climate, soil, and vegetation is therefore a crucial aspect for geosciences such as hydrology and ecology. The ecohydrology of groundwater-dependent ecosystems can be described with a modeling framework based on a stochastic process-based water balance. The model is driven by a compound marked Poisson noise representing the rainfall events and, under some simplifying, yet realistic, assumptions, it includes rainfall infiltration, root water uptake, capillary flux, and subsurface flow to/from an external water body. The framework provides the long-term probability distribution of water table depth and of soil moisture vertical profiles, enabling a quantitative study of the local hydrology with a limited number of parameters. We here apply this framework to investigate plant transpiration and root water uptake. The probability distributions of water uptake are derived from those of the soil water content and are investigated for different scenarios of climate, soil, and vegetation. The results of this approach allow for interesting speculations about the groundwater contribution to root uptake, the soil water available for plant transpiration, and the optimal strategies of root growth and plant competition. This information is useful to assess the impact of climate changes, vegetation modification, and water management operations.

Tamea, S.; Laio, F.; Ridolfi, L.; D'Odorico, P.; Rodriguez-Iturbe, I.

2009-04-01

56

Assimilation of xylem-transported CO2 is dependent on transpiration rate but is small relative to atmospheric fixation.  

PubMed

The effect of transpiration rate on internal assimilation of CO2 released from respiring cells has not previously been quantified. In this study, detached branches of Populus deltoides were allowed to take up (13)CO2-labelled solution at either high (high label, HL) or low (low label, LL) (13)CO2 concentrations. The uptake of the (13)CO2 label served as a proxy for the internal transport of respired CO2, whilst the transpiration rate was manipulated at the leaf level by altering the vapour pressure deficit (VPD) of the air. Simultaneously, leaf gas exchange was measured, allowing comparison of internal CO2 assimilation with that assimilated from the atmosphere. Subsequent (13)C analysis of branch and leaf tissues revealed that woody tissues assimilated more label under high VPD, corresponding to higher transpiration, than under low VPD. More (13)C was assimilated in leaf tissue than in woody tissue under the HL treatment, whereas more (13)C was assimilated in woody tissue than in leaf tissue under the LL treatment. The ratio of (13)CO2 assimilated from the internal source to CO2 assimilated from the atmosphere was highest for the branches under the HL and high VPD treatment, but was relatively small regardless of VPD×label treatment combination (up to 1.9%). These results showed that assimilation of internal CO2 is highly dependent on the rate of transpiration and xylem sap [CO2]. Therefore, it can be expected that the relative contribution of internal CO2 recycling to tree carbon gain is strongly dependent on factors controlling transpiration, respiration, and photosynthesis. PMID:23580747

Bloemen, Jasper; McGuire, Mary Anne; Aubrey, Doug P; Teskey, Robert O; Steppe, Kathy

2013-05-01

57

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

PubMed

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

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

2013-12-01

58

Plant ?15N Correlates with the Transpiration Efficiency of Nitrogen Acquisition in Tropical Trees1[OA  

PubMed Central

Based upon considerations of a theoretical model of 15N/14N fractionation during steady-state nitrate uptake from soil, we hypothesized that, for plants grown in a common soil environment, whole-plant ?15N (?P) should vary as a function of the transpiration efficiency of nitrogen acquisition (FN/v) and the difference between ?P and root ?15N (?P ? ?R). We tested these hypotheses with measurements of several tropical tree and liana species. Consistent with theoretical expectations, both FN/v and ?P ? ?R were significant sources of variation in ?P, and the relationship between ?P and FN/v differed between non-N2-fixing and N2-fixing species. We interpret the correlation between ?P and FN/v as resulting from variation in mineral nitrogen efflux-to-influx ratios across plasma membranes of root cells. These results provide a simple explanation of variation in ?15N of terrestrial plants and have implications for understanding nitrogen cycling in ecosystems. PMID:19726571

Cernusak, Lucas A.; Winter, Klaus; Turner, Benjamin L.

2009-01-01

59

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...

60

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

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,

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

1975-01-01

61

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

Microsoft Academic Search

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

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

1974-01-01

62

Transpiration cooling in hypersonic flight  

NASA Technical Reports Server (NTRS)

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.

Tavella, Domingo; Roberts, Leonard

1989-01-01

63

The control of transpiration by absorbed radiation  

NASA Astrophysics Data System (ADS)

Transpiration plays a key role in the hydrological cycle and models of transpiration have been used in many applications. However, our understanding of mechanisms which control the rate of transpiration is still limited being a domain of two different disciplines. Meteorologists apply the top-down approach driven by physical descriptions and water vapour transport, stomatal conductance is regarded as a boundary condition. Plant physiologists focus on the bottom-up approach and emphasize the physiological control of transpiration by stomatal conductance. It is generally accepted that transpiration is strongly influenced by the boundary layer outside the leaf and that feedback mechanisms within this layer decrease the sensitivity of transpiration to changes in stomatal conductance. This feedback mechanism is thought to increase with increasing scale from single stoma to canopy and ecosystem. In contrast, we propose a mechanism that would place much of the control inside the leaf. Most of the solar radiation reaching the leaf penetrates the epidermis with little interaction and the largest part of the energy is absorbed by chloroplasts in mesophyll cells. Thus, evaporation occurs into the intercellular air spaces of a leaf at cell walls adjacent to the chloroplasts of the leaf mesophyll and it is directly coupled to absorbed solar radiation. We present data showing that variation in the rate of transpiration and stomatal conductance at constant humidity and CO2 is closely proportional to changes in fluxes of energy (W m-2) absorbed by the leaf. Computer simulations of energy exchange between the leaf mesophyll and the atmosphere with different regimes of heat and water exchange operating on the inner and outer sides of the epidermis realistically simulate transpiration, stomatal response to a range of environmental conditions and provide a basis to calculate carbon fluxes. This approach has the potential for an up-scaling of water and carbon fluxes in canopies and ecosystems.

Pieruschka, Roland; Berry, Joseph A.

2010-05-01

64

COMBINED EFFECT OF WHITENING AND VENTILATION METHODS ON MICROCLIMATE AND TRANSPIRATION IN ROSE GREENHOUSE  

E-print Network

of inside air temperature, plant canopy temperature, growing media temperature, relative humidity theoretically. The results were compared for clear and whitewash coating on glass cover greenhouse. The results revealed that whitewash helped to reduce the plant temperature and transpiration rate

Lieth, J. Heinrich

65

Photosynthesis and Transpiration  

NSDL National Science Digital Library

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.

Society, American C.

2010-01-01

66

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

NASA Technical Reports Server (NTRS)

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.

Gokoglu, Suleyman A.; Rosner, Daniel E.

1985-01-01

67

Sap flow measurements to determine the transpiration of facade greenings  

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

68

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

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

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

2014-11-01

69

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

PubMed Central

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

Coupel-Ledru, Aude; Lebon, Eric; Christophe, Angelique; Doligez, Agnes; Cabrera-Bosquet, Llorenc; Pechier, Philippe; Hamard, Philippe; This, Patrice; Simonneau, Thierry

2014-01-01

70

Quantitative Analysis of Transpiration Stream Dynamics in an Intact Cucumber Stem by a Heat Flux Control Method  

PubMed Central

Water flux of transpiration stream in an intact stem of the 10 leaf stage cucumber plant (Cucumis sativus L. cv. Chojitsu-Ochiai) was measured by a novel system of heat flux control method with a resolution of 1 × 10?3 grams per second and a time constant of 1 minute; two heat flux control sensors were attached to the seventh internode and the stem base. The transpiration stream responded clearly to leaf transpiration and root water absorption when the plant was exposed to light, and the water flux at the stem base corresponded to the transpiration rate per plant in steady state. Root water absorption lagged about 10 minutes behind leaf transpiration. Dynamics of water fluxes were affected by the lag of water absorption in roots, and temporary water loss caused by rapid increase in leaf transpiration was buffered by about 5% of the water content in the stem. PMID:16666595

Kitano, Masaharu; Eguchi, Hiromi

1989-01-01

71

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

PubMed

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

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

72

The effects of CO2 on growth and transpiration of radish (Raphanus sativus) in hypobaria  

NASA Astrophysics Data System (ADS)

Plants grown on long-term space missions will likely be grown in low pressure environments (i.e., hypobaria). However, in hypobaria the transpiration rates of plants can increase and may result in wilting if the water is not readily replaced. It is possible to reduce transpiration by increasing the partial pressure of CO2 (pCO2), but the effects of pCO2 at high levels (>120 Pa) on the growth and transpiration of plants in hypobaria are not known. Therefore, the effects of pCO2 on the growth and transpiration of radish (Raphanus sativus var. Cherry Bomb II) in hypobaria were studied. The fresh weight (FW), leaf area, dry weight (DW), CO2 assimilation rates (CA), dark respiration rates (DR), and transpiration rates from 26 day-old radish plants that were grown for an additional seven days at different total pressures (33, 66 or 101 kPa) and pCO2 (40 Pa, 100 Pa and 180 Pa) were measured. In general, the dry weight of plants increased with CO2 enrichment and with lower total pressure. In limiting pCO2 (40 Pa) conditions, the transpiration for plants grown at 33 kPa was approximately twice that of controls (101 kPa total pressure with 40 Pa pCO2). Increasing the pCO2 from 40 Pa to 180 Pa reduced the transpiration rates for plants grown in hypobaria and in standard atmospheric pressures. However, for plants grown in hypobaria and high pCO2 (180 Pa) leaf damage was evident. Radish growth can be enhanced and transpiration reduced in hypobaria by enriching the gas phase with CO2 although at high levels leaf damage may occur.

Gohil, H. L.; Bucklin, R. A.; Correll, M. J.

2010-04-01

73

The effects of CO2 on growth and transpiration of radish (Raphanus sativus) in hypobaria  

Microsoft Academic Search

Plants grown on long-term space missions will likely be grown in low pressure environments (i.e., hypobaria). However, in hypobaria the transpiration rates of plants can increase and may result in wilting if the water is not readily replaced. It is possible to reduce transpiration by increasing the partial pressure of CO2 (pCO2), but the effects of pCO2 at high levels

H. L. Gohil; R. A. Bucklin; M. J. Correll

2010-01-01

74

The effects of CO 2 on growth and transpiration of radish ( Raphanus sativus) in hypobaria  

Microsoft Academic Search

Plants grown on long-term space missions will likely be grown in low pressure environments (i.e., hypobaria). However, in hypobaria the transpiration rates of plants can increase and may result in wilting if the water is not readily replaced. It is possible to reduce transpiration by increasing the partial pressure of CO2 (pCO2), but the effects of pCO2 at high levels

H. L. Gohil; R. A. Bucklin; M. J. Correll

2010-01-01

75

Control of transpiration by radiation  

PubMed Central

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

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

2010-01-01

76

Control of transpiration by radiation.  

PubMed

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

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

2010-07-27

77

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

Microsoft Academic Search

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

L. Schreiber; M. Riederer

1996-01-01

78

Comparison of transpiration rates among saltcedar, cottonwood and willow trees by sap flow and canopy temperature methods  

Microsoft Academic Search

Transpiration (Et), measured by stem sap flow gauges, and canopy and air temperature differential (Tc?Ta) of Populus fremontii (cottonwood), Salix gooddingii (willow) and Tamarix ramosissima (saltcedar) were compared to determine if remotely sensed canopy temperatures could be used to estimate Et or water stress in these trees in desert riparian zones of the United States and Mexico. Controlled experiments were

Pamela L Nagler; Edward P Glenn; T Lewis Thompson

2003-01-01

79

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

PubMed Central

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

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

2014-01-01

80

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

PubMed

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

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

2013-09-01

81

Transpiration of urban forests in the Los Angeles metropolitan area.  

PubMed

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

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

2011-04-01

82

Pattern of Transpiration of Four Shrub Species and Water Consumption from Shrub Stands in an Eco-Reclamation Catchment in Northwest China  

Microsoft Academic Search

The seasonal and diurnal variation in transpiration rate and stomatal conductance of four dominant shrub species (Caragana intermedia, Hippophae rhamnoides, Hedysarum leave, Salix psammophyla) planted in schemes designed to restore vegetation and conserve water in the arid soils of northwest China were studied. Transpiration rates were measured at the leaf scale using a porometer and then combined with data on

Chuan Tong; Jian-Zhou Gong; Robb Marrs; Lu Zhang; Wei-Qi Wang

2008-01-01

83

Transpiration- and growth-induced water potentials in maize  

SciTech Connect

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.

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

1984-01-01

84

Transpiration and water use by cotton plants as affected by the soil application of fatty alcohols  

E-print Network

has been found to correlate reliab'y with wats ccrrent obsess ed in the field from 24 to 48 hours following the irrigation cf s-ndy soils. This level of soil moisture is usually referred to ss field capacity. Richards (17) has described a method...-atmosphere of suction for 24 bours, tbe con?role passed from 12 to 22 percent more water than plants grown in hexadecanol. Olsen et. al. (14) added hexadecanol and o"tadecanol to corn roots by band placement. and mixing the materials w'tN tie soil; however...

Rhoads, Frederick Milton

2012-06-07

85

Transpiration cooling using air as a coolant  

SciTech Connect

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.

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

1993-02-01

86

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

E-print Network

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

Koptur, Suzanne

87

Transpiration cooled throat for hydrocarbon rocket engines  

NASA Technical Reports Server (NTRS)

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.

May, Lee R.; Burkhardt, Wendel M.

1991-01-01

88

Impact of the hydraulic capacity of plants on water and carbon fluxes in tropical South America  

Microsoft Academic Search

Angiosperms (flowering plants) have higher transpirational capacities than any other plants. Here we use climate model simulation to test the hypothesis that the high transpirational capacity of angiosperms plays a unique role in the maintenance of tropical rainforest. Their elevated transpiration rates are shown to increase recycling of precipitation up to ?300 mm\\/yr (?20% of total precipitation) averaged over the

Jung-Eun Lee; Kevin Boyce

2010-01-01

89

The function of nocturnal transpiration  

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

90

Control of Leaf Expansion Rate of Droughted Maize Plants under Fluctuating Evaporative Demand (A Superposition of Hydraulic and Chemical Messages?).  

PubMed Central

We have analyzed the possibility that chemical signaling does not entirely account for the effect of water deficit on the maize (Zea mays L.) leaf elongation rate (LER) under high evaporative demand. We followed time courses of LER (0.2-h interval) and spatial distribution of elongation rate in leaves of either water-deficient or abscisic acid (ABA)-fed plants subjected to varying transpiration rates in the field, in the greenhouse, and in the growth chamber. At low transpiration rates the effect of the soil water status on LER was related to the concentration of ABA in the xylem sap and could be mimicked by feeding artificial ABA. Transpiring plants experienced a further reduction in LER, directly linked to the transpiration rate or leaf water status. Leaf zones located at more than 20 mm from the ligule stopped expanding during the day and renewed expansion during the night. Neither ABA concentration in the xylem sap, which did not appreciably vary during the day, nor ABA flux into shoots could account for the effect of evaporative demand. In particular, maximum LER was observed simultaneously with a minimum ABA flux in the droughted plants, but with a maximum ABA flux in ABA-fed plants. All data were interpreted as the superposition of two additive effects: the first involved ABA signaling and was observed during the night and in ABA-fed plants, and the second involved the transpiration rate and was observed even in well-watered plants. We suggest that a hydraulic signal is the most likely candidate for this second effect. PMID:12223750

Salah, HBH.; Tardieu, F.

1997-01-01

91

RELATIONSHIP BETWEEN TRANSPIRATION AND NITROGEN UPTAKE BY PEPPER (CAPSICUM ANNUUM) AS MEDIATED BY VAPOR PRESSURE DEFICIT  

E-print Network

RELATIONSHIP BETWEEN TRANSPIRATION AND NITROGEN UPTAKE BY PEPPER (CAPSICUM ANNUUM) AS MEDIATED As a consequence of photosynthesis, plants lose water rapidly via transpiration. However, transpiration may benefit was to study the possible relationship between transpiration and nitrogen uptake. Bell peppers (Capsicum annuum

Teskey, Robert O.

92

An experimental set?up to study carbon, water, and nitrate uptake rates by hydroponically grown plants  

Microsoft Academic Search

The experimental system described allows concomitant hourly measurements of CO2, H2O, and NO3 uptake rates by plants grown hydroponically in a greenhouse. Plants are enclosed in an airtight chamber through which air flows at a controlled speed. Carbon dioxide exchange and transpiration rates are determined from respective differences of concentrations of CO2 and water vapor of the air at the

J. L. Andriolo; J. Le Bot; C. Gary; G. Sappe; P. Orlando; B. Brunel; C. Sarrouy

1996-01-01

93

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

PubMed

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

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

2012-04-01

94

Terrestrial water fluxes dominated by transpiration.  

PubMed

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

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

2013-04-18

95

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

E-print Network

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

Katul, Gabriel

96

Influence of Transpiration Suppressants, Sprinkler Irrigation and Moisture Levels on Transpiration and Evapotranspiration  

E-print Network

determined. Microclimatic data as influenced by treatments were determined. Estimates of influences of treatments on transpiration were evaluated with thermoelectric sensors. Tomato and citrus plant parts were analyzed for certain chemical properties. Diurnal...

Gerard, C. J.

97

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

NASA Technical Reports Server (NTRS)

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.

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

2003-01-01

98

Numerical Analysis of Convection/Transpiration Cooling  

NASA Technical Reports Server (NTRS)

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.

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

1999-01-01

99

Numerical Analysis of Convection/Transpiration Cooling  

NASA Technical Reports Server (NTRS)

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.

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

1999-01-01

100

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.

101

Importance of air movement for promoting gas and heat exchanges between plants and atmosphere under controlled environments  

Microsoft Academic Search

The effects of the air velocity less than 1.3 m s?1on net photosynthetic rates, transpiration rates and water use efficiencies of plant seedlings canopies and single leaves were assessed. Control of air movement is important to enhance gas exchange between plants and the ambient air, and would consequently be important to promote plant growth. The suppression of the transpiration rate

Yoshiaki Kitaya

102

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

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.

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

2009-01-01

103

Fruit transpiration in kiwifruit: environmental drivers and predictive model  

PubMed Central

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

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

2012-01-01

104

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

SciTech Connect

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.

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

1980-01-01

105

Deposition control using transpiration: Final report  

SciTech Connect

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.

Kozlu, H.; Louis, J.F.

1986-11-01

106

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

E-print Network

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

Lieth, J. Heinrich

107

Do hydraulic redistribution and nocturnal transpiration facilitate nutrient acquisition in Aspalathus linearis?  

PubMed

The significance of soil water redistribution by roots and nocturnal transpiration for nutrient acquisition were assessed for deep-rooted 3-year-old leguminous Aspalathus linearis shrubs of the Cape Floristic Region (South Africa). We hypothesised that hydraulic redistribution and nocturnal transpiration facilitate nutrient acquisition by releasing moisture in shallow soil to enable acquisition of shallow-soil nutrients during the summer drought periods and by driving water fluxes from deep to shallow soil powering mass-flow nutrient acquisition, respectively. A. linearis was supplied with sub-surface (1-m-deep) irrigation rates of 0, 2 or 4 L day(-1 )plant(-1). Some plants were unfertilized, whilst others were surface- or deep-fertilized (1 m depth) with Na(15)NO3 and CaP/FePO4. We also supplied deuterium oxide ((2)H2O) at 1 m depth at dusk and measured its predawn redistribution to shallow soil and plant stems. Hydraulic redistribution of deep water was substantial across all treatments, accounting for 34-72 % of surface-soil predawn moisture. Fourteen days after fertilization, the surface-fertilized plants exhibited increased hydraulic redistribution and increased (15)N and P acquisition with higher rates of deep-irrigation. Deep-fertilization also increased hydraulic redistribution to surface soils, although these plants additionally accumulated (2)H2O in their stem tissue overnight, probably due to nocturnal transpiration. Plants engaged in nocturnal transpiration also increased (15)N and P acquisition from deep fertilizer sources. Thus, both nocturnal transpiration and hydraulic redistribution increased acquisition of shallow soil N and P, possibly through a combination of increased nutrient availability and mobility. PMID:24972698

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

2014-08-01

108

Influence of shading on net photosynthetic and transpiration rates, stomatal diffusive resistance, nitrate reductase and biomass productivity of a woody legume tree species ( Erythrina variegata Lam.)  

Microsoft Academic Search

In view of the sun and shade adaptations of plants to semi-arid climatic conditions investigations were undertaken withErythrina variegata Lam. The studies revealed that shading decreased root and shoot growth, leaf density, leaf area, specific leaf weight, relative\\u000a growth rate and relative leaf growth rate. Consequently the dry biomass accumulation was adversely affected in shade grown\\u000a plants. Synthesis of chlorophyll

K Muthuchelian; Kailash Paliwal; A Gnanam

1989-01-01

109

Geographic isolates of Glomus increase root growth and whole-plant transpiration of Citrus seedlings grown with high phosphorus  

Microsoft Academic Search

Four Glomus species\\/isolates from arid, semi-arid and mesic areas were evaluated for their effects on growth and water use characteristics\\u000a of young Citrus volkameriana (?Volkamer? lemon) under well-watered conditions, followed by three soil-drying episodes of increasing severity (soil moisture\\u000a tensions of –0.02, –0.06, and –0.08 MPa) and recovery conditions. Arbuscular mycorrhizal (AM) plants were also compared to\\u000a non-AM plants given

Matthew W. Fidelibus; Chris A. Martin; Jean C. Stutz

2001-01-01

110

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

E-print Network

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

Flury, Markus

111

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

NASA Technical Reports Server (NTRS)

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.

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

1976-01-01

112

Determining the Amount of Transpiration from a Schoolyard Tree  

NSDL National Science Digital Library

Sttudents determine transpiration rate of five leaves, then estimate the number of leaves on the tree and total leaf surface area. Pounds of water transpired by the tree in a 24 hour period can then be estimated. Additional calculations are suggested.

BEGIN:VCARD VERSION:2.1 FN:Laurence Pomeroy N:Pomeroy;Laurence ORG:Santiago High School REV:2005-04-12 END:VCARD

1994-07-30

113

Plant Populations and Seeding Rates for Soybeans  

E-print Network

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

Holland, Jeffrey

114

Transpiration Control Of Aerodynamics Via Porous Surfaces  

NASA Technical Reports Server (NTRS)

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.

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

1993-01-01

115

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

PubMed Central

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

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

1998-01-01

116

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

E-print Network

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

Vrugt, Jasper A.

117

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

Microsoft Academic Search

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

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

1995-01-01

118

Trends and rates of microevolution in plants  

Microsoft Academic Search

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

Elizabeth Bone; Agnes Farres

2001-01-01

119

Native Trees and Salt Cedar: Quantifying Transpiration at Intermittent and Perennial Streamflows on the San Pedro River  

NASA Astrophysics Data System (ADS)

Native cottonwood-willow forests that historically dominated south-western riparian areas are being replaced by salt cedar (Tamarix ramosissima) on the majority of regulated western rivers. Some studies of salt cedar have indicated its water use is considerably greater than native trees and depletes alluvial aquifers of groundwater; however, other studies have shown low to moderate water use by salt cedar. Results have varied on temporal and spatial scales making it difficult to draw firm conclusions. We compared whole plant transpiration by native riparian cottonwood (Populus fremontii) trees and salt cedar in co-occurring communities at the upper and lower San Pedro River in Arizona during 2006 and 2007, respectively. Water use by both species was monitored and quantified using the heat balance sap flow technique at intermittent and perennial reaches during the pre- monsoon season, a period of high atmospheric water demand. Our 2006 measurements in a riparian transition zone at an intermittent reach of the San Pedro River appeared to differ with earlier studies that salt cedar has higher transpiration rates, as cottonwoods and salt cedar demonstrated similar, low transpiration rates. However transpiration results from a 2007 study on these same species at a perennial reach of the San Pedro River indicate significantly higher transpiration by salt cedar and moderate increases for cottonwoods compared to the intermittent site.

McGuire, R. R.; Glenn, E. P.; Scott, R. L.; Moran, M. S.

2007-12-01

120

Coordination of Leaf Photosynthesis, Transpiration, and Structural Traits in Rice and Wild Relatives (Genus Oryza).  

PubMed

The genus Oryza, which includes rice (Oryza sativa and Oryza glaberrima) and wild relatives, is a useful genus to study leaf properties in order to identify structural features that control CO(2) access to chloroplasts, photosynthesis, water use efficiency, and drought tolerance. Traits, 26 structural and 17 functional, associated with photosynthesis and transpiration were quantified on 24 accessions (representatives of 17 species and eight genomes). Hypotheses of associations within, and between, structure, photosynthesis, and transpiration were tested. Two main clusters of positively interrelated leaf traits were identified: in the first cluster were structural features, leaf thickness (Thick(leaf)), mesophyll (M) cell surface area exposed to intercellular air space per unit of leaf surface area (S(mes)), and M cell size; a second group included functional traits, net photosynthetic rate, transpiration rate, M conductance to CO(2) diffusion (g(m)), stomatal conductance to gas diffusion (g(s)), and the g(m)/g(s) ratio.While net photosynthetic rate was positively correlated with gm, neither was significantly linked with any individual structural traits. The results suggest that changes in gm depend on covariations of multiple leaf (S(mes)) and M cell (including cell wall thickness) structural traits. There was an inverse relationship between Thick(leaf) and transpiration rate and a significant positive association between Thick(leaf) and leaf transpiration efficiency. Interestingly, high g(m) together with high g(m)/g(s) and a low S(mes)/g(m) ratio (M resistance to CO(2) diffusion per unit of cell surface area exposed to intercellular air space) appear to be ideal for supporting leaf photosynthesis while preserving water; in addition, thick M cell walls may be beneficial for plant drought tolerance. PMID:23669746

Giuliani, Rita; Koteyeva, Nuria; Voznesenskaya, Elena; Evans, Marc A; Cousins, Asaph B; Edwards, Gerald E

2013-07-01

121

UBC Social Ecological Economic Development Studies (SEEDS) Student Report The Effect of Environmental Changes on the Photosynthesis and Transpiration of  

E-print Network

of Environmental Changes on the Photosynthesis and Transpiration of Rates of Evergreen and Deciduous Trees during of Environmental Changes on the Photosynthesis and Transpiration of Rates of Evergreen and Deciduous Trees during in the photosynthesis (CO2 uptake and fixation) and transpiration (water loss) rates of evergreen and deciduous trees

122

Transpiration Cooling Experiment  

NASA Technical Reports Server (NTRS)

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.

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

1997-01-01

123

Idaho Chemical Processing Plant failure rate database.  

National Technical Information Service (NTIS)

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,...

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

1995-01-01

124

Thermographic measurements on plant leaves Christoph S. Garbea, Ulrich Schurrb and Bernd Jhnea  

E-print Network

feature for vital factors such as gas exchange and water transport affixed to which is the nutrient physiology such as transpiration rates, heat capacity per unit area of the leaf and the water flow velocity. The latent heat flux of a plant, which is directly proportional to the transpiration rate, can be measured

Garbe, Christoph S.

125

Transpiration coefficients for three Great Basin shrubs  

Microsoft Academic Search

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

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

2001-01-01

126

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

E-print Network

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

Paris-Sud XI, Université de

127

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

E-print Network

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

Paris-Sud XI, Université de

128

Does night-time transpiration contribute to anisohydric behaviour in a Vitis vinifera cultivar?  

PubMed

The hypothesis that vines of the Semillon wine grape variety show anisohydric behaviour was tested, i.e. that tissue hydration is unstable under fluctuating environmental conditions. Stomatal conductance and transpiration rates from leaves were measured during the day and at night. Leaf water potential (Psi(l)) in Semillon was negatively correlated to vapour pressure deficit (VPD) both predawn and during the day. Furthermore, Psi(l) fell to significantly lower values than in any of the nine other varieties examined. Night-time values of stomatal conductance (g(n)) and transpiration (E(n)) in Semillon were up to four times higher than in other varieties; plants enclosed in plastic bags overnight to reduce E(n) resulted in better plant-soil equilibration so that predawn Psi(l) in Semillon was the same as in Grenache. These data indicate that the hypothesis is supported, and that night-time transpiration contributes significantly to the low Psi(l) values in Semillon during warm, dry nights. The other contributing factor is daytime stomatal conductance (g(day)), which in Semillon leaves was higher than in other varieties, although the decline in g(day) with increasing VPD was greater in Semillon than in Shiraz or Grenache. The high values of g(day) were associated with high rates of transpiration (E(day)) by Semillon through a day when VPD reached 4.5 kPa. When compared to other varieties, Semillon was not unusual in terms of root length density, stomatal density, xylem sap abscisic acid, or leaf electrolyte leakage. Night-time and daytime water loss and insufficient stomatal regulation therefore account for the tendency to anisohydric behaviour shown by Semillon. PMID:19584116

Rogiers, Suzy Y; Greer, Dennis H; Hutton, Ron J; Landsberg, Joe J

2009-01-01

129

Idaho Chemical Processing Plant failure rate database  

SciTech Connect

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.

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

1995-08-01

130

Ozone-induced reductions in photosynthesis and transpiration: Parameterizing the Community Land Model (CLM)  

NASA Astrophysics Data System (ADS)

Humans are indirectly increasing concentrations of surface ozone (O3) through industrial processes. Ozone is known to have negative impacts on plants, including reductions in crop yields, plant growth, and visible leaf injury. Research also suggests that O3 exposure differentially affects photosynthesis and transpiration because biochemical aspects of photosynthesis are damaged in addition to stomatal conductance, the common link that controls both processes. However, most models incorporate O3 damage as a decrease in photosynthesis, with stomatal conductance responding linearly through the coupling of photosynthesis and conductance calculations. The observed differential effects of O3 on photosynthesis and conductance are not explicitly expressed in most modeling efforts, potentially causing larger decreases in transpiration. We ran five independent simulations of the CLM that compare current methods of incorporating O3 as a decrease in photosynthesis to a new method of separating photosynthesis and transpiration responses to O3 by independently modifying each parameter. We also determine the magnitude of both direct decreases to photosynthesis and transpiration and decreases caused by feedbacks in each parameter. Results show that traditional methods of modeling O3 effects by decreasing photosynthesis cause linear decreases in predicted transpiration that are ~20% larger than observed decreases in transpiration. However, modeled decreases in photosynthesis and transpiration that are incorporated independently of one another predict observed decreases in photosynthesis and improve transpiration predictions by ~13%. Therefore, models best predict carbon and water fluxes when incorporating O3-induced decreases in photosynthesis and transpiration independently.

Lombardozzi, D.; Bonan, G. B.; Levis, S.; Sparks, J. P.

2010-12-01

131

Coordination of Leaf Photosynthesis, Transpiration, and Structural Traits in Rice and Wild Relatives (Genus Oryza)1[W][OA  

PubMed Central

The genus Oryza, which includes rice (Oryza sativa and Oryza glaberrima) and wild relatives, is a useful genus to study leaf properties in order to identify structural features that control CO2 access to chloroplasts, photosynthesis, water use efficiency, and drought tolerance. Traits, 26 structural and 17 functional, associated with photosynthesis and transpiration were quantified on 24 accessions (representatives of 17 species and eight genomes). Hypotheses of associations within, and between, structure, photosynthesis, and transpiration were tested. Two main clusters of positively interrelated leaf traits were identified: in the first cluster were structural features, leaf thickness (Thickleaf), mesophyll (M) cell surface area exposed to intercellular air space per unit of leaf surface area (Smes), and M cell size; a second group included functional traits, net photosynthetic rate, transpiration rate, M conductance to CO2 diffusion (gm), stomatal conductance to gas diffusion (gs), and the gm/gs ratio. While net photosynthetic rate was positively correlated with gm, neither was significantly linked with any individual structural traits. The results suggest that changes in gm depend on covariations of multiple leaf (Smes) and M cell (including cell wall thickness) structural traits. There was an inverse relationship between Thickleaf and transpiration rate and a significant positive association between Thickleaf and leaf transpiration efficiency. Interestingly, high gm together with high gm/gs and a low Smes/gm ratio (M resistance to CO2 diffusion per unit of cell surface area exposed to intercellular air space) appear to be ideal for supporting leaf photosynthesis while preserving water; in addition, thick M cell walls may be beneficial for plant drought tolerance. PMID:23669746

Giuliani, Rita; Koteyeva, Nuria; Voznesenskaya, Elena; Evans, Marc A.; Cousins, Asaph B.; Edwards, Gerald E.

2013-01-01

132

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

Microsoft Academic Search

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

Albert Olioso; Toby N. Carlson; Nadine Brisson

1996-01-01

133

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

SciTech Connect

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.

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

134

Thermodynamics of cuticular transpiration Allen G. Gibbs *  

E-print Network

Review Thermodynamics of cuticular transpiration§ Allen G. Gibbs * School of Life Sciences, 4505 S . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1067 4. Thermodynamics of transport processes Accepted 6 May 2011 Keywords: Cuticle Humidity Thermodynamics Transpiration Water vapor A B S T R A C

Ahmad, Sajjad

135

Transpiration and growth-induced water potentials in maize  

Microsoft Academic Search

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

M. E. Westgate; J. S. Boyer

1984-01-01

136

Original article Field comparison of transpiration,  

E-print Network

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

Paris-Sud XI, Université de

137

Optimal Transpiration Boundary Control for Aeroacoustics  

E-print Network

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

Heinkenschloss, Matthias

138

Original article Transpiration and stomatal conductance  

E-print Network

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

Paris-Sud XI, Université de

139

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

NASA Astrophysics Data System (ADS)

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.

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

2012-12-01

140

A hierarchical analysis of the interactive effects of elevated CO2 and water availability on the nitrogen and transpiration productivities of velvet mesquite seedlings.  

PubMed

In this study we apply new extensions of classical growth analysis to assess the interactive effects of elevated CO2 and differences in water availability on the leaf-nitrogen and transpiration productivities of velvet mesquite (Prosopis velutina Woot.) seedlings. The models relate transpiration productivity (biomass gained per mass of water transpired per day) and leaf-nitrogen productivity (biomass gain per unit leaf N per day) to whole-plant relative growth rate (RGR) and to each other, allowing a comprehensive hierarchical analysis of how physiological and morphological responses to the treatments interact with each other to affect plant growth. Elevated CO2 led to highly significant increases in N and transpiration productivities but reduced leaf N per unit leaf area and transpiration per unit leaf area, resulting in no net effect of CO2 on the RGR of seedlings. In contrast, higher water availability led to an increase in leaf-tissue thickness or density without affecting leaf N concentration, resulting in a higher leaf N per unit leaf area and consequently a higher assimilatory capacity per unit leaf area. The net effect was a marginal increase in seedling RGR. Perhaps most important from an ecological perspective was a 41% reduction in whole-plant water use due to elevated CO2. These results demonstrate that even in the absence of CO2 effects on integrative measures of plant growth such as RGR, highly significant effects may be observed at the physiological and morphological level that effectively cancel each other out. The quantitative framework presented here enables some of these tradeoffs to be identified and related directly to each other and to plant growth. PMID:15322897

Peterson, Andrew G; Neofotis, Peter G

2004-12-01

141

Does hydraulic lift or nighttime transpiration facilitate nitrogen acquisition?  

Microsoft Academic Search

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

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

2008-01-01

142

Accommodation between transpiring vegetation and the convective boundary layer  

Microsoft Academic Search

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

J. L. Monteith

1995-01-01

143

Comparative photosynthesis, growth and transpiration of two species of Atriplex  

Microsoft Academic Search

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).

R. O. Slatyer

1970-01-01

144

Transpiration Induces Radial Turgor Pressure Gradients in Wheat and Maize Roots.  

PubMed Central

Previous studies have shown both the presence and the absence of radial turgor and osmotic pressure gradients across the cortex of roots. In this work, gradients were sought in the roots of wheat (Triticum aestivum) and maize (Zea mays) under conditions in which transpiration flux across the root was varied This was done by altering the relative humidity above the plant, by excising the root, or by using plants in which the leaves were too young to transpire. Roots of different ages (4-65 d) were studied and radial profiles at different distances from the tip (5-30 mm) were measured. In both species, gradients of turgor and osmotic pressure (increasing inward) were found under transpiring conditions but not when transpiration was inhibited. The presence of radial turgor and osmotic pressure gradients, and the behavior of the gradient when transpiration is interrupted, indicate that active membrane transport or radial solvent drag may play an important role in the distribution of solutes across the root cortex in transpiring plants. Contrary to the conventional view, the flow of water and solutes across the symplastic pathway through the plasmodesmata cannot be inwardly directed under transpiring conditions. PMID:12231957

Rygol, J.; Pritchard, J.; Zhu, J. J.; Tomos, A. D.; Zimmermann, U.

1993-01-01

145

Transpiration Induces Radial Turgor Pressure Gradients in Wheat and Maize Roots.  

PubMed

Previous studies have shown both the presence and the absence of radial turgor and osmotic pressure gradients across the cortex of roots. In this work, gradients were sought in the roots of wheat (Triticum aestivum) and maize (Zea mays) under conditions in which transpiration flux across the root was varied This was done by altering the relative humidity above the plant, by excising the root, or by using plants in which the leaves were too young to transpire. Roots of different ages (4-65 d) were studied and radial profiles at different distances from the tip (5-30 mm) were measured. In both species, gradients of turgor and osmotic pressure (increasing inward) were found under transpiring conditions but not when transpiration was inhibited. The presence of radial turgor and osmotic pressure gradients, and the behavior of the gradient when transpiration is interrupted, indicate that active membrane transport or radial solvent drag may play an important role in the distribution of solutes across the root cortex in transpiring plants. Contrary to the conventional view, the flow of water and solutes across the symplastic pathway through the plasmodesmata cannot be inwardly directed under transpiring conditions. PMID:12231957

Rygol, J.; Pritchard, J.; Zhu, J. J.; Tomos, A. D.; Zimmermann, U.

1993-10-01

146

Gas-phase and transpiration-driven mechanisms for volatilization through wetland macrophytes.  

PubMed

Natural and constructed wetlands have gained attention as potential tools for remediation of shallow sediments and groundwater contaminated with volatile organic compounds (VOCs). Wetland macrophytes are known to enhance rates of contaminant removal via volatilization, but the magnitude of different volatilization mechanisms, and the relationship between volatilization rates and contaminant physiochemical properties, remain poorly understood. Greenhouse mesocosm experiments using the volatile tracer sulfur hexafluoride were conducted to determine the relative magnitudes of gas-phase and transpiration-driven volatilization mechanisms. A numerical model for vegetation-mediated volatilization was developed, calibrated with tracer measurements, and used to predict plant-mediated volatilization of common VOCs as well as quantify the contribution of different volatilization pathways. Model simulations agree with conclusions from previous work that transpiration is the main driver for volatilization of VOCs, but also demonstrate that vapor-phase transport in wetland plants is significant, and can represent up to 50% of the total flux for compounds with greater volatility like vinyl chloride. PMID:22509995

Reid, Matthew C; Jaffé, Peter R

2012-05-15

147

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

SciTech Connect

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.

Temple, P.J.

1986-01-01

148

Spatial Variability of Tree Transpiration Along a Soil Drainage Gradient of Boreal Black Spruce Forest  

NASA Astrophysics Data System (ADS)

Boreal forests are an integral component in obtaining a predictive understanding of global climate change because they comprise 33% of the world's forests and store large amounts of carbon. Much of this carbon storage is a result of peat formation in cold, poorly-drained soils. Transpiration plays a crucial role in the interaction between carbon and water cycles due to stomatal control of these fluxes. The primary focus of this study is to quantify the spatial variability and drivers of tree transpiration in boreal forest stands across a well- to poorly-drained soil drainage gradient. Species composition of this region of boreal forest changes during succession in well-drained soils from being primarily dominated by Picea mariana with co-dominant Pinus banksiana and Populus tremuloides in younger stands to being dominated solely by Picea marianain older stands. Poorly-drained soils are dominated by Picea mariana and change little with succession. Previous work in well-drained stands showed that 1) tree transpiration changed substantially with stand age due to sapwood-to-leaf area ratio dynamics and 2) minimum leaf water potential (?) was kept constant to prevent excessive cavitation. We hypothesized that 1) minimum ? would be constant, 2) transpiration would be proportional to the sapwood-to-leaf area ratio across a soil drainage gradient, and 3) spatial relationships between trees would vary depending on stomatal responses to vapor pressure deficit (D). We tested these hypotheses by measuring ? of 33 trees and sap flux from 204 trees utilizing cyclic sampling constructed to study spatial relationships. Measurements were conducted at a 42-year-old stand representing maximum tree diversity during succession. There were no significant differences between growing season averaged ? in well- (-0.35 and -1.37 for pre-dawn and mid-day respectively) and poorly- drained soil conditions (-0.38 and -1.41 for pre-dawn and mid-day respectively) for Picea mariana. Water use results of Picea mariana differed between drainage conditions when expressed per unit xylem area with trees in poorly-drained soils experiencing higher rates than trees in well-drained areas (101.79 and 83.02 g cm-2 day-1 respectively). In contrast, when expressed as transpiration per tree, trees on well-drained soils had higher rates than those in poorly-drained locations (366.96 and 216.82 g tree-1 day-1 respectively). This indicates that tree size, reflected in sapwood area per ground area, which is constrained by anaerobic conditions across well- to poorly-drained areas, is driving differences in tree transpiration. Initial spatial analyses show that spatial autocorrelation decreases from 51.3 to 24.6 meters as D increases from 0.9 to 2.1 kPa. This phenomenon is explained by tree hydraulics and more patchy stomatal response as trees regulate water loss. Thus, regional scale bottom-up process models of boreal forest transpiration can be simplified with respect to soil drainage while retaining mechanistic rigor with respect to plant hydraulics.

Angstmann, J. L.; Ewers, B. E.; Kwon, H.; Bond-Lamberty, B.; Amiro, B.; Gower, S. T.

2008-12-01

149

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

SciTech Connect

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.

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

150

Groundwater Constraints on Simulated Transpiration Variability over Southeastern Australian Forests  

E-print Network

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

Evans, Jason

151

Transpiration Cooling Of Hypersonic Blunt Body  

NASA Technical Reports Server (NTRS)

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.

Henline, William D.

1991-01-01

152

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

Microsoft Academic Search

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

Phillip L. Thompson; Liz A. Ramer; Aaron P. Guffey; Jerald L. Schnoor

1998-01-01

153

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

SciTech Connect

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.

Wise, D.P.

1997-12-01

154

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

NASA Technical Reports Server (NTRS)

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.

Kubota, Hirotoshi

1975-01-01

155

Transpiration And Regenerative Cooling Of Rocket Engine  

NASA Technical Reports Server (NTRS)

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.

Obrien, Charles J.

1989-01-01

156

The unexpected effects of wind speeds on plant water use efficiency  

NASA Astrophysics Data System (ADS)

Transpiration and heat exchange by plant leaves are coupled physiological processes of significant ecohydrological importance. The common practice of modelling transpiration as an isothermal process (assuming equal leaf and air temperatures) may introduce significant bias into estimates of transpiration rates and water use efficiency (WUE, the amount of carbon gained by photosynthesis per unit of water lost by transpiration). In a recent study (Schymanski et al., 2013), we investigated effects of fluctuating irradiance (sunflecks) on leaf thermal regime and transpiration rates using a physically-based leaf model. Results suggest that leaf temperatures may deviate substantially from air temperature, leading to greatly modified transpiration rates compared to isothermal conditions. This presentation reports a systematic study of the effects of wind speed on leaf heat and gas exchange rates. Surprisingly, under certain conditions, an increase in wind speed can suppress transpiration rates. This is due to feedbacks between sensible heat flux, leaf temperature, leaf-to-air vapour pressure deficit and latent heat flux. The model predicts that for high wind velocities, the same leaf conductance (for water vapour and carbon dioxide) can be maintained with less evaporative losses. If this leaf-scale effect is consistent across most leaves, it may have profound implications for canopy-scale water use efficiency under globally decreasing wind speeds. Experimental verification of the modelling study is under way and first results will be presented.

Schymanski, S. J.; Or, D.

2013-12-01

157

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

SciTech Connect

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)

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

2006-07-01

158

A Phytotoxicity Test Using Transpiration of Willows  

Microsoft Academic Search

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

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

2000-01-01

159

Effect of Flashing Light on Plant Growth Rate  

Microsoft Academic Search

NUMEROUS investigations have been reported relating photosynthetic light efficiency and plant growth. Dickson1 has found in Lemna minor a growth rate decline as the length of alternating periods of light and darkness decreased, with a minimum growth rate at a 1-min light period; but at a 5-sec light period the growth rate was comparable with that under a 12-h photoperiod.

M. H. Dickson; S. E. Chua

1963-01-01

160

Carbon dioxide enrichment and temperature effects on cotton canopy photosynthesis, transpiration, and water-use efficiency  

Microsoft Academic Search

The objectives of this study were to evaluate effects of ambient and double ambient [CO2] at a range of growing temperatures on photosynthesis, respiration, transpiration, water-use efficiency and dry matter accumulation of cotton plants (Gossypium hirsutum L., cv. DPL 50). In Experiment I, plants were grown outdoors until first bloom, then transferred into naturally lit growth chambers and grown for

V. R. Reddy; K. R. Reddy; H. F. Hodges

1995-01-01

161

The Inappropriate Use of Crop Transpiration Coefficients (Kc) to Estimate Evapotranspiration in Arid Ecosystems: A Review  

Microsoft Academic Search

The transpiration coefficient (Kc) method estimates evapotranspiration as a proportion of the evapotranspiration of a reference crop growing in ideal conditions. This approach was designed for irrigated crops and assumes that plants are not subjected to resource limitations. Other assumptions are that plants have high leaf area index and little stomatal resistance to water loss. These conditions are not common

Ricardo Mata-González; Terry McLendon; David W. Martin

2005-01-01

162

Transpirational demand affects aquaporin expression in poplar roots  

PubMed Central

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

Hacke, Uwe G.

2013-01-01

163

Plant respirometer enables high resolution of oxygen consumption rates  

NASA Technical Reports Server (NTRS)

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.

Foster, D. L.

1966-01-01

164

Effect of plants on sunspace passive solar heating  

SciTech Connect

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.

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

1985-01-01

165

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

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

Bauerle, William L; Bowden, Joseph D

2011-08-01

166

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

E-print Network

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...

Heraganahally Kapanigowda, Mohankumar

2012-07-16

167

Lattice Boltzmann model for thermal transpiration.  

PubMed

The conventional Navier-Stokes-Fourier equations with no-slip boundary conditions are unable to capture the phenomenon of gas thermal transpiration. While kinetic approaches such as the direct simulation Monte Carlo method and direct solution of the Boltzmann equation can predict thermal transpiration, these methods are often beyond the reach of current computer technology, especially for complex three-dimensional flows. We present a computationally efficient nonequilibrium thermal lattice Boltzmann model for simulating temperature-gradient-induced flows. The good agreement between our model and kinetic approaches demonstrates the capabilities of the proposed lattice Boltzmann method. PMID:19391876

Tang, G H; Zhang, Y H; Gu, X J; Barber, R W; Emerson, D R

2009-02-01

168

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

NASA Astrophysics Data System (ADS)

Water-limited ecosystems are characterized by precipitation with low annual totals and significant temporal variability, transpiration that is limited by soil-moisture availability, and infiltration events that may only partially rewet the vegetation root zone. Average transpiration in such environments is controlled by precipitation, and accurate predictions of vegetation health require adequate representation of temporal variation in the timing and intensity of plant uptake. Complexities introduced by variability in depth of infiltration, distribution of roots, and a plant's ability to compensate for spatially heterogeneous soil moisture suggest a minimum vertical resolution required for satisfactory representation of plant behavior. To explore the effect of vertical resolution on predictions of transpiration, we conduct a series of numerical experiments, comparing the results from models of varying resolution for a range of plant and climate conditions. From temporal and spatial scales of the underlying processes and desired output, we develop dimensionless parameters that indicate the adequacy of a finite-resolution model with respect to reproducing characteristics of plant transpiration over multiple growing seasons. These parameters may be used to determine the spatial resolution required to predict vegetation health in water-limited ecosystems.

Guswa, Andrew J.; Celia, Michael A.; Rodriguez-Iturbe, Ignacio

2004-05-01

169

Effect, uptake and disposition of nitrobenzene in several terrestrial plants  

Microsoft Academic Search

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.

C. McFarlane; T. Pfleeger; J. Fletcher

1990-01-01

170

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

Microsoft Academic Search

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

Fulco Ludwig; Rebecca A. Jewitt; Lisa A Donovan

2006-01-01

171

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

NASA Astrophysics Data System (ADS)

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.

Gong, Daozhi; Kang, Shaozhong; Zhang, Jianhua

2005-08-01

172

Energy conversion using thermal transpiration : optimization of a Knudsen compressor  

E-print Network

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 ...

Klein, Toby A. (Toby Anna)

2012-01-01

173

Using the dual approach of FAO-56 for partitioning ET into soil and plant1 components for olive orchards in a semi-arid region2  

E-print Network

transpiration and soil evaporation) of an olive (Olea europaea L.) orchard in the semi arid27 region of Tensift conditions.38 Since the dual approach predicts separately soil evaporation and plant transpiration, an39 an acceptable estimate of plant transpiration and soil42 evaporation. The associated RMSE of plant transpiration

Paris-Sud XI, Université de

174

Free convection over a vertical porous plate with transpiration  

NASA Technical Reports Server (NTRS)

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.

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

1974-01-01

175

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...

176

Estimating Evaporation and Transpiration from Climatological Observations  

Microsoft Academic Search

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.

F. I. Morton

1975-01-01

177

Application of crop gas exchange and transpiration data obtained with CEEF to global change problem  

Microsoft Academic Search

In order to predict carbon sequestration of vegetation with the future rise in atmospheric CO2 concentration, [CO2] and temperature, long term effects of high [CO2] and high temperature on responses of both photosynthesis and transpiration of plants as a whole community to environmental parameters need to be elucidated. Especially in the last decade, many studies on photosynthetic acclimation to elevated

Y. Tako; R. Arai; K. Otsubo; K. Nitta

2001-01-01

178

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

E-print Network

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

Boyer, Edmond

179

Original article Intra-and interannual variations of transpiration,  

E-print Network

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

Paris-Sud XI, Université de

180

Optimisation des relations entre transpiration et photosynthse. Observations propos  

E-print Network

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

Paris-Sud XI, Université de

181

Reduction of tropical land region precipitation variability via transpiration  

E-print Network

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

Gentine, Pierre

182

Improvements in plant growth rate using underwater discharge  

NASA Astrophysics Data System (ADS)

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.

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

2013-03-01

183

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

SciTech Connect

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.

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

1985-01-01

184

Transpiration characteristics of a rubber plantation in central Cambodia.  

PubMed

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

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

185

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)

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.

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

2014-05-01

186

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...

187

Linking carbon isotopes and carbon-water exchange of plants across different scales  

Microsoft Academic Search

The anthropogenic rise in atmospheric CO2 levels may lead to increased photosynthetic uptake while transpiration rates remain constant or are reduced. Changes in plant regulation of carbon uptake and water loss also affect the carbon isotope signatures of plant material. But environmental conditions may change in addition to CO2. The resulting combination of factors can have different effects on the

U. Seibt; A. Rajabi; H. Griffiths; J. Berry

2007-01-01

188

Preciptation, Evaporation, and Transpiration Activity  

NSDL National Science Digital Library

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.

Townsend-Small, Amy

189

Transpired Air Collectors - Ventilation Preheating  

SciTech Connect

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.

Christensen, C.

2006-06-22

190

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

Microsoft Academic Search

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).

G. N. Geller; W. K. Smith

1982-01-01

191

Theoretical evolutionary rates in plant groups and the fossil record  

Microsoft Academic Search

An attempt is made to estimate a mathematical expression for the underlying mean rate of evolution in organic systems, and\\u000a in particular those of various plant groupings. This was done by considering the thermodynamic constraints on any system tending\\u000a towards greater levels of complexity with time (or showing a progressive decrease in randomness). Orderliness is here equated\\u000a with genetic-information, and

Karl J. Niklas

1977-01-01

192

Temporal and spatial changes in grassland transpiration detected using Landsat TM and ETM+ imagery  

Microsoft Academic Search

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 successfully applied over heterogeneous terrain with little a priori information. In this study, WDI was derived from a 10-year,

C. D. Holifield; S. McElroy; M. S. Moran; R. Bryant; T. Miura; W. E. Emmerich

193

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

NASA Technical Reports Server (NTRS)

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.

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

1991-01-01

194

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...

195

Environmental energy and evolutionary rates in flowering plants.  

PubMed Central

The latitudinal gradient in species richness is a pervasive feature of the living world, but its underlying causes remain unclear. We evaluated the hypothesis that environmental energy drives evolutionary rates and thereby diversification in flowering plants. We estimated energy levels across angiosperm family distributions in terms of evapotranspiration, temperature and UV radiation taken from satellite and climate databases. Using the most comprehensive DNA-based phylogenetic tree for angiosperms to date, analysis of 86 sister-family comparisons shows that molecular evolutionary rates have indeed been faster in high-energy regions, but that this is not an intermediate step between energy and diversity. Energy has strong, but independent effects on both species richness and molecular evolutionary rates. PMID:15475341

Davies, T. Jonathan; Savolainen, Vincent; Chase, Mark W.; Moat, Justin; Barraclough, Timothy G.

2004-01-01

196

Response of mycorrhizal periwinkle plants to aster yellows phytoplasma infection.  

PubMed

The objective of our research was to assess if arbuscular mycorrhizal (AM) fungal colonization can modify the effect of infection by two aster yellows phytoplasma strains (AY1, AYSim) in Catharanthus roseus plants. Both phytoplasma strains had a negative effect on the root fresh weight, but they differed in symptoms appearance and in their influence on photosynthetic and transpiration rates of the periwinkle plants. AM plants showed significantly reduced shoot fresh weight, while the transpiration rate was significantly increased. AM fungal colonization significantly affected shoot height and fresh weight of the plants infected by each phytoplasma strains as well as the root system of plants infected with the more aggressive AYSim phytoplasma strain. Double inoculation did not reduce the negative effects induced with phytoplasma alone on the photosynthetic activity of phytoplasma-infected plants. PMID:19756778

Kami?ska, Maria; Klamkowski, Krzysztof; Berniak, Hanna; Sowik, Iwona

2010-03-01

197

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

SciTech Connect

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%.

Galanter, S.A.

1980-11-01

198

Article original Utilisation d'une chambre de transpiration portable  

E-print Network

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

Paris-Sud XI, Université de

199

Plant Responses to High CO 2 Concentration in the Atmosphere  

Microsoft Academic Search

The impact of continuous rise in ambient CO2 concentration (AC) in the atmosphere on different facets of growth of crop plants is assessed. The effects of CO2 enrichment (EC) on plant growth, C3 and C4 photosynthesis, source-sink ratio, partitioning and translocation of metabolites, photosynthetic enzymes, respiratory rate,\\u000a leaf area index, stomatal conductance (q\\u000a \\u000a s\\u000a ), \\u000a transpiration rate, biomass production and

V. C. Saralabai; M. Vivekanandan; R. Suresh Babu

1997-01-01

200

Stem Extension Rate in Light-Grown Plants 1  

PubMed Central

Low temperature pulses have two effects on the circadian rhythm exhibited by stem extension rate of green Chenopodium rubrum plants. First, low temperature pulses have the same effect on the phasing of the rhythm as a dark period interrupting continuous light. Second, low temperature pulses stimulate stem extension rate during the 10 hours immediately following the end of the pulse. A difference in temperature between soil and air increases this effect. In any case, it is the change in temperature which is essential and not a specific temperature. Effects of light and temperature on phasing and amplitude of the rhythm explain why the maximal stem growth is observed under normal photo-thermoperiodic conditions, i.e. a high temperature during the photoperiod and a low temperature during the dark period. PMID:16664462

Lecharny, Alain; Schwall, Michael; Wagner, Edgar

1985-01-01

201

Heat exchanger with transpired, highly porous fins  

DOEpatents

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.

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

2002-01-01

202

Lattice Boltzmann approach to thermal transpiration  

SciTech Connect

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.

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

2006-11-15

203

Simultaneous viscous-inviscid coupling via transpiration  

SciTech Connect

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.

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

1995-09-01

204

Night-time transpiration can decrease hydraulic redistribution.  

PubMed

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

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

2009-08-01

205

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

E-print Network

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

Nowak, Robert S.

206

Risk-taking plants  

PubMed Central

Water scarcity is a critical limitation for agricultural systems. Two different water management strategies have evolved in plants: an isohydric strategy and an anisohydric strategy. Isohydric plants maintain a constant midday leaf water potential (?leaf) when water is abundant, as well as under drought conditions, by reducing stomatal conductance as necessary to limit transpiration. Anisohydric plants have more variable ?leaf and keep their stomata open and photosynthetic rates high for longer periods, even in the presence of decreasing leaf water potential. This risk-taking behavior of anisohydric plants might be beneficial when water is abundant, as well as under moderately stressful conditions. However, under conditions of intense drought, this behavior might endanger the plant. We will discuss the advantages and disadvantages of these two water-usage strategies and their effects on the plant’s ability to tolerate abiotic and biotic stress. The involvement of plant tonoplast AQPs in this process will also be discussed. PMID:22751307

Sade, Nir; Gebremedhin, Alem; Moshelion, Menachem

2012-01-01

207

A Coupled Model of Photosynthesis, Stomatal Conductance and Transpiration for a Rose Leaf (Rosa hybrida L.)  

PubMed Central

The following three models were combined to predict simultaneously photosynthesis, stomatal conductance, transpiration and leaf temperature of a rose leaf: the biochemical model of photosynthesis of Farquhar, von Caemmerer and Berry (1980, Planta 149: 78–90), the stomatal conductance model of Ball, Woodrow and Berry (In: Biggens J, ed. Progress in photosynthesis research. The Netherlands: Martinus Nijhoff Publishers), and an energy balance model. The photosynthetic parameters: maximum carboxylation rate, potential rate of electron transport and rate of triose phosphate utilization, and their temperature dependence were determined using gas exchange data of fully expanded, young, sunlit leaves. The stomatal conductance model was calibrated independently. Prediction of net photosynthesis by the coupled model agreed well with the validation data, but the model tended to underestimate rates of stomatal conductance and transpiration. The coupled model developed in this study can be used to assist growers making environmental control decisions in glasshouse production. PMID:12730065

KIM, SOO?HYUNG; LIETH, J. HEINRICH

2003-01-01

208

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

SciTech Connect

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.

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

1982-03-01

209

Combustion chamber struts can be effectively transpiration cooled  

NASA Technical Reports Server (NTRS)

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.

Palmer, G. H.

1966-01-01

210

The relative role of stomata in transpiration and assimilation  

Microsoft Academic Search

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

I. R. Cowan; J. H. Troughton

1971-01-01

211

Effects of Kaolin and Pinolene Film-forming Polymers on Water Relations and Photosynthetic Rate of Tuberose (Polianthes tuberosa L.)  

Microsoft Academic Search

The effects of pinolene-base Vapor Gard (VG) emulsion type film and Kaolin (Surround WP) particle type film antitranspirants on stomatal behavior, water status, carbon assimilation and transpiration rate of tuberose (Polianthes tuberosa L.) cv. double plants grown under the irrigation regimes of 100, 80 and 60% of total evapotranspiration (ET) values were investigated to select the most suitable antitranspirant for

Ansary E. Moftah; Abdulrahman I. Al-Humaid

2005-01-01

212

On the Resistance to Transpiration of the Sites of Evaporation within the Leaf 1  

PubMed Central

The rates of transpiration from the upper and lower surfaces of leaves of Gossypium hirsutum, Xanthium strumarium, and Zea mays were compared with the rates at which helium diffused across those leaves. There was no evidence for effects of CO2 concentration or rate of evaporation on the resistance to water loss from the evaporating surface (“resistance of the mesophyll wall to transpiration”) and no evidence for any significant wall resistance in turgid tissues. The possible existence of a wall resistance was also tested in leaves of Commelina communis and Tulipa gesneriana whose epidermis could be easily peeled. Only when an epidermis was removed from a leaf, evaporation from the mesophyll tissue declined. We conclude that under conditions relevant to studies of stomatal behavior, the water vapor pressure at the sites of evaporation is equal to the saturation vapor pressure. PMID:16660404

Farquhar, Graham D.; Raschke, Klaus

1978-01-01

213

Transpiration affects soil CO2 production in a dry grassland  

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

214

Planting Thoughts  

NSDL National Science Digital Library

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.

Integrated Teaching And Learning Program

215

Transpiration as a Function of Soil Temperature and Soil Water Stress  

PubMed Central

An apparatus was developed for the measurement of transpiration rates of Trifolium repens. The transpiration rates were measured under controlled conditions of soil water stress and soil temperature. Other environmental parameters such as air temperature, relative humidity, light intensity and air speed were held constant. Diffusive resistances were calculated and stomatal aperture changes were recorded for all treatment combinations. A significant interaction between soil water stress and soil temperature was observed for stomatal closures. Stomatal closure was observed even in the so-called wet range of soil water stress. An increase in mesophyll resistance or incipient drying was observed for several treatment combinations. The mesophyll resistance was shown to increase as soil water stress increased. Images PMID:16656536

Cox, L. M.; Boersma, L.

1967-01-01

216

Influence of Pratylenchus penetrans on Plant Growth and Water Relations in Potato.  

PubMed

Plants of potato (Solanum tuberosum) cultivars Katahdin and Superior were inoculated with 0, 1,500, or 15,000 Pratylenchus penetrans. Transpiration, measured in the greenhouse with a porometer after 56 days of growth, was not significantly different among nematode inoculum levels or between cultivars. The rate of xylem exudation from decapitated root systems of Katahdin plants inoculated with 1,500 or 15,000 P. penetrans and Superior plants inoculated with 15,000 P. penetrans was lower than from noninoculated plants. Root weight of Katahdin and Superior was not affected by P. penetrans inoculum level. Transpiration of plants inoculated with 0, 500, 5,000 or 50,000 P. penetrans was recorded weekly from 14 to 56 days after planting. No consistent effects of nematode inoculum density on transpiration rate were observed. Root hydraulic conductivity was lower in Katahdin plants inoculated with 266 P. penetrans per plant and in Chippewa with 5,081 per plant than in noninoculated plants. Nematodes reduced leaf area of Superior, Chippewa, and Katahdin and root dry weight of Chippewa but had no effect on growth of Hudson, Onaway, or Russet Burbank plants. Assessing nematode effects on root hydraulic conductivity may provide a measure of the tolerance of potato cultivars to nematodes. PMID:19294196

Kotcon, J B; Loria, R

1986-07-01

217

Short-term responses of leaf growth rate to water deficit scale up to whole-plant and crop levels: an integrated modelling approach in maize.  

PubMed

Physiological and genetic studies of leaf growth often focus on short-term responses, leaving a gap to whole-plant models that predict biomass accumulation, transpiration and yield at crop scale. To bridge this gap, we developed a model that combines an existing model of leaf 6 expansion in response to short-term environmental variations with a model coordinating the development of all leaves of a plant. The latter was based on: (1) rates of leaf initiation, appearance and end of elongation measured in field experiments; and (2) the hypothesis of an independence of the growth between leaves. The resulting whole-plant leaf model was integrated into the generic crop model APSIM which provided dynamic feedback of environmental conditions to the leaf model and allowed simulation of crop growth at canopy level. The model was tested in 12 field situations with contrasting temperature, evaporative demand and soil water status. In observed and simulated data, high evaporative demand reduced leaf area at the whole-plant level, and short water deficits affected only leaves developing during the stress, either visible or still hidden in the whorl. The model adequately simulated whole-plant profiles of leaf area with a single set of parameters that applied to the same hybrid in all experiments. It was also suitable to predict biomass accumulation and yield of a similar hybrid grown in different conditions. This model extends to field conditions existing knowledge of the environmental controls of leaf elongation, and can be used to simulate how their genetic controls flow through to yield. PMID:18088328

Chenu, Karine; Chapman, Scott C; Hammer, Graeme L; McLean, Greg; Salah, Halim Ben Haj; Tardieu, François

2008-03-01

218

A Field Survey of Respiration Rates in Leaves of Arctic Plants  

Microsoft Academic Search

In a survey of several plant species found at Churchill, Manitoba, in the transition zone between the low and subarctic regions, we measured leaf respiration in terms of total respiration and alternative pathway respiration rates. Leaves of arctic plants exhibit higher rates of total respiration and alternative (cyanide insensitive) respiration than temperate species. There is a negative correlation between plant

AMY K. McNULTY; W. RAYMOND CUMMINS; ANDREW PELLIZZARI

1988-01-01

219

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

NASA Astrophysics Data System (ADS)

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.

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

2013-12-01

220

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

PubMed

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

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

2009-09-01

221

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

E-print Network

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...

Beck, Andy Dwayne

2012-06-07

222

Extensive variation in synonymous substitution rates in mitochondrial genes of seed plants  

Microsoft Academic Search

BACKGROUND: It has long been known that rates of synonymous substitutions are unusually low in mitochondrial genes of flowering and other land plants. Although two dramatic exceptions to this pattern have recently been reported, it is unclear how often major increases in substitution rates occur during plant mitochondrial evolution and what the overall magnitude of substitution rate variation is across

Jeffrey P Mower; Pascal Touzet; Julie S Gummow; Lynda F Delph; Jeffrey D Palmer

2007-01-01

223

Transpiring wall supercritical water oxidation test reactor design report  

SciTech Connect

Sandia National Laboratories is working with GenCorp, Aerojet and Foster Wheeler Development Corporation to develop a transpiring wall supercritical water oxidation reactor. The transpiring wall reactor promises to mitigate problems of salt deposition and corrosion by forming a protective boundary layer of pure supercritical water. A laboratory scale test reactor has been assembled to demonstrate the concept. A 1/4 scale transpiring wall reactor was designed and fabricated by Aerojet using their platelet technology. Sandia`s Engineering Evaluation Reactor serves as a test bed to supply, pressurize and heat the waste; collect, measure and analyze the effluent; and control operation of the system. This report describes the design, test capabilities, and operation of this versatile and unique test system with the transpiring wall reactor.

Haroldsen, B.L.; Ariizumi, D.Y.; Mills, B.E.; Brown, B.G. [Sandia National Labs., Livermore, CA (United States). Engineering for Transportation and Environment Dept.; Rousar, D.C. [GenCorp Aerojet, Sacramento, CA (United States)

1996-02-01

224

Canopy Transpiration in a Chronosequence of Central Siberian Pine Forests  

NASA Technical Reports Server (NTRS)

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.

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

1998-01-01

225

Numerical Simulation Study on Transpired Solar Air Collector  

E-print Network

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...

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

2006-01-01

226

The determination of transpiration efficiency coefficient for common bean  

NASA Astrophysics Data System (ADS)

A number of studies have been conducted to determine species specific transpiration efficiency coefficient. Although the value is available for some C3 legumes, no value has been determined for common beans within the semi-arid tropics. The coefficient is useful in modelling crop water use as it has been found to be conservative over a range of climates when differences in vapour pressure deficits are accounted for. The objective of the experiment was to determine the transpiration efficiency coefficient for common beans for use in modelling within the semi-arid region of South Africa. Common bean ( Phaseoulus vulgaris L.) was grown on a weighing lysimeter during the 2000/2001 and 2001/2002 seasons. Transpiration was measured on hourly basis using the weighing lysimeter and the data integrated over the growing season to determine the seasonal transpiration for the crop. At the same time hourly measurement of canopy vapour pressure deficit was made using wet and dry bulb resistance thermometers housed in mini-shelters at 200-400 mm height. Wet and dry bulb temperature data was also collected at the nearby standard automatic weather station and used to normalize the transpiration efficiency. Transpiration efficiency for the common bean was 1.33 and 1.93 g kg -1 which when normalized and root adjusted, gave a transpiration efficiency coefficient of 3.02 and 3.51 g kPa kg -1 for the 2000/2001 and 2001/2002 seasons respectively. A mean transpiration efficiency coefficient of 3.26 ± 0.25 g kPa kg -1 was adopted for the two seasons. This value is fairly consistent with those obtained for other C3 legumes species, confirming the conservativeness of the coefficient and therefore its usefulness as modelling parameter.

Ogindo, H. O.; Walker, S.

227

Transpiration during life cycle in controlled wheat growth  

NASA Technical Reports Server (NTRS)

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.

Volk, Tyler; Rummel, John D.

1990-01-01

228

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

NASA Astrophysics Data System (ADS)

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.

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

2014-08-01

229

Implications of Advanced Crew Escape Suit Transpiration for the Orion Program  

NASA Technical Reports Server (NTRS)

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.

Bue, Grant; Kuznetz, Lawrence

2009-01-01

230

An experimental study on the efficiency of transpiration cooling in laminar and turbulent hypersonic flows  

NASA Astrophysics Data System (ADS)

An experimental study on the efficiency of transpiration cooling in hypersonic laminar and turbulent flow regimes is carried out in the Hypersonic Windtunnel Cologne with a focus on the aerothermal problems downstream of the cooled model part. The model is made of a material of low thermal conductivity (PEEK) with an integrated probe of a porous material. The experimental setup allows the direct comparison of the thermal behavior of transpiration cooling to a well-defined and radiatively cooled reference surface. Experiments are performed at Mach number of 6 and two different Reynolds numbers. Air, argon and helium are used as coolants at various flow rates, in order to identify the influence of coolant medium on cooling efficiency. The cooling efficiency of air and argon is comparable. Helium provides significantly higher cooling efficiency at the same blowing ratio, i.e. same coolant mass flow rate. The experimental data shows that the efficiency of the transpiration cooling in turbulent flows is much lower than in laminar flow.

Gülhan, A.; Braun, S.

2011-03-01

231

A dynamical system perspective on plant hydraulic failure  

NASA Astrophysics Data System (ADS)

is governed by leaf water status that depends on the difference between the rates of transpiration and water supply from the soil and through the plant xylem. When transpiration increases compared to water supply, the leaf water potential reaches a more negative equilibrium, leading to water stress. Both high atmospheric vapor pressure deficit and low soil moisture increase the water demand while decreasing the supply due to lowered soil-to-root conductance and xylem cavitation. Therefore, dry conditions may eventually reduce the leaf water potential to the point of collapsing the plant hydraulic system. This "hydraulic failure" is shown to correspond to a fold bifurcation where the environmental parameters (vapor pressure deficit and soil moisture) trigger the loss of a physiologically sustainable equilibrium. Using a minimal plant hydraulic model, coordination among plant hydraulic traits is shown to result in increased resilience to environmental stresses, thereby impeding hydraulic failure unless hydraulic traits deteriorate due to prolonged water shortage or other damages.

Manzoni, Stefano; Katul, Gabriel; Porporato, Amilcare

2014-06-01

232

Short-term responses of leaf growth rate to water deficit scale up to whole-plant and crop levels: an integrated modelling approach in maize  

Microsoft Academic Search

Physiological and genetic studies of leaf growth often focus on short-term responses, leaving a gap to whole-plant models that predict biomass accumulation, transpiration and yield at crop scale. To bridge this gap, we developed a model that combines an existing model of leaf 6 expansion in response to short-term environmental variations with a model coordinating the development of all leaves

KARINE CHENU; SCOTT C. CHAPMAN; GRAEME L. HAMMER; GREG MCLEAN; HALIM BEN HAJ SALAH; FRANÇOIS TARDIEU

2008-01-01

233

Biological and environmental controls on tree transpiration in a suburban landscape  

NASA Astrophysics Data System (ADS)

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.

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

2010-12-01

234

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

NASA Astrophysics Data System (ADS)

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.

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

2013-12-01

235

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

Microsoft Academic Search

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

Galanter

1980-01-01

236

Does transpiration matter to the hydrogen isotope ratios of leaf wax n-alkanes? (Invited)  

NASA Astrophysics Data System (ADS)

Transpiration and evaporation from soils both affect he hydrogen isotope composition of leaf water, but the extent to which they effect the hydrogen isotope ratio of leaf wax lipids is still under debate. To address this question, we analyzed hydrogen isotope ratios of high-molecular weight n-alkanes (?Dl) and oxygen isotope ratios of ?-cellulose (?18OC) for C3 and C4 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 ?Dl signatures. In the different relative humidity environments of the growth chambers, we observed clear and predictable effects of leaf-water enrichment on ?18OC 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 ?Dl values. In field samples, we saw clear evidence of enrichment (correlating with relative humidity of the field sites) in both ?18OC and ?Dl. These seemingly contrasting results can 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 ?Dl, 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 ?18OC values. In contrast, the calculated leaf water hydrogen isotope ratios are more enriched than what is required to predict observed ?Dl values. These calculations lend support to the conclusion that while ?18OC reflects both soil evaporation and transpiration, ?Dl 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.

McInerney, F. A.; Helliker, B. R.; Freeman, K. H.

2010-12-01

237

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 in Colorado's middle Arkansas Valley by Susan C. Spackman Panjabi Colorado Natural Heritage Program College............................................................................................ 20 Measuring insect visitation rates

238

The partitioning of evapotranspiration into evaporation and transpiration: an experimental design assessing the effects of changes in vegetation cover  

NSDL National Science Digital Library

This project seeks to improve the studentÃÂs understanding of the terrestrial water budget by exploring the dynamics of one of its major components: evapotranspiration, a process that includes the accumulation of both evaporation from the soil and plant surfaces and plant transpiration. Traditionally in both hydrological and ecological sciences, evapotranspiration has been treated as a single component. However, the partitioning into its major components, soil evaporation and plant transpiration, can have important ecological and hydrological implications, especially in the context of current and predicted changes in climate and vegetation. Notably, this project helps our understanding of the effects of changes in vegetation (as expected from current changes in climate and land use) on the partitioning of evapotranspiration into its major components and how they feedback into other ecological and hydrological processes.

Gerst, Katharine L.

2010-02-16

239

Thermal transpiration through single walled carbon nanotubes and graphene channels  

SciTech Connect

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.

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

240

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

E-print Network

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

Laaksonen, Toni

241

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

SciTech Connect

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.

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

1992-12-31

242

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

NASA Astrophysics Data System (ADS)

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.

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

2014-09-01

243

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

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

Cochran-Stafira, D. Liane

244

Venezuelan extraction plant expanding to 1 bcfd rating  

SciTech Connect

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.

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

1990-12-03

245

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

PubMed Central

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

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

2014-01-01

246

Effect of aerosols on evapo-transpiration  

NASA Astrophysics Data System (ADS)

Aerosol direct radiative forcing (ARF) at surface is estimated from instantaneous, simultaneous observations of global radiation and aerosol optical depth (AOD) during winter, pre-monsoon and monsoon seasons over a tropical Indian station at the south-eastern end of Indo Gangetic basin. A comparison of observed and model derived ARFs is made and possible reasons for mismatch are discussed. Aerosol-induced reduction in solar visible (0.4-0.7 ?m) spectrum energy (SWvis), contributing 44% to total broad band (0.3-3.0 ?m) energy (SW), and its effect on surface energy fluxes are discussed in this study. Aerosols on an average reduce SWvis at surface by ?27%. SWvis reduces by 14.5 W m-2 for a 0.1 increase in AOD when single scattering albedo (SSA) is 0.979 where as it reduces by 67.5 W m-2 when SSA is 0.867 indicating the significant effect of absorbing aerosols. Effect of ARF on net radiation, Rn, sensible heat flux, H and latent heat flux/evapo-transpiration, LE are estimated using the observed ratios of Rn/SW, H/Rn and LE/Rn, having reasonably good correlation. Observed Rn/SW varies between 0.59 and 0.75 with a correlation of 0.99 between them. LE, calculated by energy balance method, varies from 56% to 74% of Rn but with a lesser correlation, the possible reasons are discussed. For a given ARF, LE decreases by ?14% and Rn by ?15% with respect to observed LE and Rn respectively. The reduction in LE increases from 37% to 54% of ARF when LE increases from 220 W m-2 to 440 W m-2, suggesting that wet soil induces relatively larger reduction in evaporation. The results agree with earlier model sensitivity studies that Rn reduces more with increase in aerosol absorption which is compensated by proportionate reductions in H and LE depending on soil and atmospheric conditions.

Murthy, B. S.; Latha, R.; Manoj, Kumar; Mahanti, N. C.

2014-06-01

247

Transpiration cooled ultraviolet sol-gel silica optics  

NASA Astrophysics Data System (ADS)

All rocket guidance systems essentially require broadband optical transmission windows. These windows must also be temperature insensitive to transmission, thermal shock resistant, thermally stable, reasonably strong, and impact resistant. At hypersonic velocity, convective cooling is preferred to radiative cooling. Transpiration cooling is a novel and effective mode of convective cooling. Porous silica windows offer excellent rocket windows for transpiration cooling at a relatively inexpensive price. Sol-gel technology is an enabling technology which facilitates the fabrication of these rocket windows. This research used sol-gel technology to demonstrate the concept of transpiration-cooled porous silica windows. These windows were fabricated with various pore sizes and characterized with respect to gas diffusion, transpiration, high temperature transmission, thermal stability and shock resistance, hardness, impact resistance, and strength. The manufacturability aspect was also addressed. The diffusion of various gases through porous silica windows was studied and their permeabilities measured. In the experimental range, Knusden diffusion seemed to be the predominant mass transport mechanism. At a low transpiration velocity of 0.52 cm/s of helium, a 44 C temperature drop was observed showing the promise of this material for rocket window application. High temperature spectroscopy showed improved performance. The porous silica windows had thermal stability and thermal shock resistance and reasonable mechanical properties.

Seth, Vinay K.; Noques, Jean-Luc

1991-04-01

248

Extensive variation in synonymous substitution rates in mitochondrial genes of seed plants  

PubMed Central

Background It has long been known that rates of synonymous substitutions are unusually low in mitochondrial genes of flowering and other land plants. Although two dramatic exceptions to this pattern have recently been reported, it is unclear how often major increases in substitution rates occur during plant mitochondrial evolution and what the overall magnitude of substitution rate variation is across plants. Results A broad survey was undertaken to evaluate synonymous substitution rates in mitochondrial genes of angiosperms and gymnosperms. Although most taxa conform to the generality that plant mitochondrial sequences evolve slowly, additional cases of highly accelerated rates were found. We explore in detail one of these new cases, within the genus Silene. A roughly 100-fold increase in synonymous substitution rate is estimated to have taken place within the last 5 million years and involves only one of ten species of Silene sampled in this study. Examples of unusually slow sequence evolution were also identified. Comparison of the fastest and slowest lineages shows that synonymous substitution rates vary by four orders of magnitude across seed plants. In other words, some plant mitochondrial lineages accumulate more synonymous change in 10,000 years than do others in 100 million years. Several perplexing cases of gene-to-gene variation in sequence divergence within a plant were uncovered. Some of these probably reflect interesting biological phenomena, such as horizontal gene transfer, mitochondrial-to-nucleus transfer, and intragenomic variation in mitochondrial substitution rates, whereas others are likely the result of various kinds of errors. Conclusion The extremes of synonymous substitution rates measured here constitute by far the largest known range of rate variation for any group of organisms. These results highlight the utility of examining absolute substitution rates in a phylogenetic context rather than by traditional pairwise methods. Why substitution rates are generally so low in plant mitochondrial genomes yet occasionally increase dramatically remains mysterious. PMID:17688696

Mower, Jeffrey P; Touzet, Pascal; Gummow, Julie S; Delph, Lynda F; Palmer, Jeffrey D

2007-01-01

249

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

SciTech Connect

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.

Slinn, W.G.N.

1987-05-01

250

Study of deposition control using transpiration. Technical progress report  

SciTech Connect

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.

Louis, J.F.; Kozlu, H.

1984-12-01

251

Effect of elevated atmospheric carbon dioxide and open-top chambers on transpiration in a tallgrass prairie  

Microsoft Academic Search

Increasing concentrations of atmospheric carbon dioxide (COâ) may influence plant-water relations in natural and agricultural ecosystems. A tallgrass prairie near Manhattan, KS, was exposed to elevated atmospheric COâ using open-top chambers (OTCs). Heat balance sap flow gauges were used to measure transpiration in ironweed [Vernonia baldwini var. interior (Small) Schub.], aCâforb, and on individual grass culms of big bluestem (Andropogan

Dale J. Bremer; Jay M. Ham; Clenton E. Owensby

1996-01-01

252

Unprecedented heterogeneity in the synonymous substitution rate within a plant genome.  

PubMed

The synonymous substitution rate varies widely among species, but it is generally quite stable within a genome due to the absence of strong selective pressures. In plants, plastid genes tend to evolve faster than mitochondrial genes, rate variation among species generally correlates between the mitochondrial and plastid genomes, and few examples of intragenomic rate heterogeneity exist. To study the extent of substitution rate variation between and within plant organellar genomes, we sequenced the complete mitochondrial and plastid genomes from the bugleweed, Ajuga reptans, which was previously shown to exhibit rate heterogeneity for several mitochondrial genes. Substitution rates were accelerated specifically in the mitochondrial genome, which contrasts with correlated plastid and mitochondrial rate changes in most other angiosperms. Strikingly, we uncovered a 340-fold range of synonymous substitution rate variation among Ajuga mitochondrial genes. This is by far the largest amount of synonymous rate heterogeneity ever reported for a genome, but the evolutionary forces driving this phenomenon are unclear. Selective effects on synonymous sites in plant mitochondria are generally weak and thus unlikely to generate such unprecedented intragenomic rate heterogeneity. Quickly evolving genes are not clustered in the genome, arguing against localized hypermutation, although it is possible that they were clustered ancestrally given the high rate of genomic rearrangement in plant mitochondria. Mutagenic retroprocessing, involving error-prone reverse transcription and genomic integration of mature transcripts, is hypothesized as another potential explanation. PMID:24557444

Zhu, Andan; Guo, Wenhu; Jain, Kanika; Mower, Jeffrey P

2014-05-01

253

Glycine-Glomus-Rhizobium Symbiosis: V. Effects of Mycorrhiza on Nodule Activity and Transpiration in Soybeans under Drought Stress.  

PubMed

Soybean (Glycine max [L.] Merr.) plants were nodulated (Bradyrhizobium japonicum) and either inoculated with the vesicular-arbuscular mycorrhizal (VAM) fungus Glomus mosseae (Nicol. & Gerd.) Gerd. and Trappe or left uncolonized. All plants were grown unstressed for 21 days initially. After this period, some VAM and non-VAM plants were exposed to four 8-day drought cycles while others were kept well watered. Drought cycles were terminated by rewatering when soil moisture potentials reached -1.2 megapascal. Nodule development and activity, transpiration, leaf conductance, leaf and root parameters including fresh and dry weight, and N and P nutrition of VAM plants and of non-VAM, P-fed plants grown under the same controlled conditions were compared. All parameters, except N content, were greater in VAM plants than in P-fed, non-VAM plants when under stress. The opposite was generally true in the unstressed comparisons. Transpiration and leaf conductance were significantly greater in stressed VAM than in non-VAM plants during the first half of the final stress cycle. Values for both VAM and non-VAM plants decreased linearly with time during the cycle and converged at a high level of stress (-1.2 megapascal). Effects of VAM fungi on the consequences of drought stress relative to P nutrition and leaf gas exchange are discussed in the light of these findings and those reported in the literature. PMID:16665641

Bethlenfalvay, G J; Brown, M S; Mihara, K L; Stafford, A E

1987-09-01

254

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

E-print Network

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

Jacob, Jamey

255

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

NASA Technical Reports Server (NTRS)

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.

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

1994-01-01

256

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

NASA Astrophysics Data System (ADS)

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.

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

2011-01-01

257

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

NASA Technical Reports Server (NTRS)

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.

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

1972-01-01

258

Latitudinal variation in plant size and relative growth rate in Arabidopsis thaliana  

Microsoft Academic Search

Latitude is an important determinant of local environmental conditions that affect plant growth. Forty ecotypes of Arabidopsis thaliana were selected from a wide range of latitudes (from 16N to 63N) to investigate genetic variation in plant size and relative\\u000a growth rate (RGR) along a latitudinal gradient. Plants were grown in a greenhouse for 31 days, during which period three consecutive

Bo Li; Jun-Ichirou Suzuki; Toshihiko Hara

1998-01-01

259

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

Microsoft Academic Search

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

J. J. James; J. H. Richards

2005-01-01

260

Contemporary evolution of plant growth rate following experimental removal of herbivores.  

PubMed

Herbivores are credited with driving the evolutionary diversification of plant defensive strategies over macroevolutionary time. For this to be true, herbivores must also cause short-term evolution within plant populations, but few studies have experimentally tested this prediction. We addressed this gap using a long-term manipulative field experiment where exclosures protected 22 plant populations from natural rabbit herbivory for <1 to 26 years. We collected seeds of Rumex acetosa L. (Polygonaceae) from our plots and grew them in a common greenhouse environment to quantify evolved differences among populations in individual plant growth rate, tolerance to herbivory, competitive ability, and the concentration of secondary metabolites (tannins and oxalate) implicated in defense against herbivores. In 26 years without rabbit herbivory, plant growth rate decreased linearly by 30%. We argue that plant growth rate has evolved as a defense against intense rabbit herbivory. In contrast, we found no change in tolerance to herbivory or concentrations of secondary metabolites. We also found no change in competitive ability, suggesting that contemporary evolution may not feed back to alter ecological interactions within this plant community. Our results combined with those of other studies show that the evolution of gross morphological traits such as growth rate in response to herbivory may be common, which calls into question assumptions about some of the most popular theories of plant defense. PMID:23598357

Turley, Nash E; Odell, Walter C; Schaefer, Hanno; Everwand, Georg; Crawley, Michael J; Johnson, Marc T J

2013-05-01

261

Plant and Environment Interactions Uptake Rates of Thorium Progeny in a Semiarid Environment  

Microsoft Academic Search

It has been reported that the mobility of thorium is restricted in plants because of adsorption on cell wall The release rates and transformation processes that influence the material, and that thorium plant concentrations were mobility, biological uptake, and transfer of radionuclides are essential typically several orders of magnitude lower than soil to the assessment of the health effects in

Yvonne McClellan; Robert August; James Gosz; Steve Gann; Robert Parmenter; Martin Nelson; Mark Harper

262

Response of ammonium removal to growth and transpiration of Juncus effusus during the treatment of artificial sewage in laboratory-scale wetlands.  

PubMed

The correlation between nitrogen removal and the role of the plants in the rhizosphere of constructed wetlands are the subject of continuous discussion, but knowledge is still insufficient. Since the influence of plant growth and physiological activity on ammonium removal has not been well characterized in constructed wetlands so far, this aspect is investigated in more detail in model wetlands under defined laboratory conditions using Juncus effusus for treating an artificial sewage. Growth and physiological activity, such as plant transpiration, have been found to correlate with both the efficiency of ammonium removal within the rhizosphere of J. effusus and the methane formation. The uptake of ammonium by growing plant stocks is within in a range of 45.5%, but under conditions of plant growth stagnation, a further nearly complete removal of the ammonium load points to the likely existence of additional nitrogen removal processes. In this way, a linear correlation between the ammonium concentration inside the rhizosphere and the transpiration of the plant stocks implies that an influence of plant physiological activity on the efficiency of N-removal exists. Furthermore, a linear correlation between methane concentration and plant transpiration has been estimated. The findings indicate a fast response of redox processes to plant activities. Accordingly, not only the influence of plant transpiration activity on the plant-internal convective gas transport, the radial oxygen loss by the plant roots and the efficiency of nitrification within the rhizosphere, but also the nitrogen gas released by phytovolatilization are discussed. The results achieved by using an unplanted control system are different in principle and characterized by a low efficiency of ammonium removal and a high methane enrichment of up to a maximum of 72.7% saturation. PMID:23764577

Wiessner, A; Kappelmeyer, U; Kaestner, M; Schultze-Nobre, L; Kuschk, P

2013-09-01

263

REGULAR PAPER Effects of flooding on leaf development, transpiration,  

E-print Network

REGULAR PAPER Effects of flooding on leaf development, transpiration, and photosynthesis angusti- folia, occurs in occasionally flooded, low elevation zones along river valleys near the North, which are com- monly flood-tolerant. We investigated the flood response of narrowleaf cottonwoods

Letts, Matthew

264

The competition between liquid and vapor transport in transpiring leaves.  

PubMed

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

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

2014-04-01

265

Numerical simulation of transpiration cooling through porous , T. Gotzen1  

E-print Network

55, 52056 Aachen SUMMARY Transpiration cooling using ceramic matrix composite (CMC) materials to facilitate such numerical simulations for a carbon/carbon material mounted in the side wall of a hot gas against high thermal loads by coating it with special materials. In contrast, active systems, which

266

TRANSPIRATION AND HYDRAULIC STRATEGIES IN A PINON-JUNIPER WOODLAND  

Microsoft Academic Search

Anthropogenic climate change is likely to alter the patterns of moisture availability globally. The consequences of these changes on species distributions and ecosystem function are largely unknown, but possibly predictable based on key ecophysio- logical differences among currently coexisting species. In this study, we examined the environmental and biological controls on transpiration from a pinon-juniper (Pinus edulis- Juniperus osteosperma) woodland

A. G. WEST; K. R. HULTINE; J. S. S PERRY; J. R. EHLERINGER

2008-01-01

267

Leaf and environmental parameters influencing transpiration: Theory and field measurements  

Microsoft Academic Search

The influence of variations in the boundary air layer thickness on transpirtion due to changes in leaf dimension or wind speed was evaluated at a given stomatal resistance (rs) for various combinations of air temperature (Ta) and total absorbed solar energy expressed as a fraction of full sunlight (Sffs). Predicted transpiration was found to either increase or decrease for increases

W. K. Smith; G. N. Geller

1980-01-01

268

Physiologie vgtale Effet de la saison sur la transpiration  

E-print Network

Physiologie végétale Effet de la saison sur la transpiration de feuilles de rosiers cv Sonia ( Rosa hybrida cv Sonia) were grown in rockwool in 2 heated greenhouses:1 control (referred as the low relative humidity (RH) greenhouse) and1 with RH control (high RH greenhouse). Two electrical conductivity

Paris-Sud XI, Université de

269

Seasonal patterns of daily net photosynthesis, transpiration and net primary productivity of Juncus roemerianus and Spartina alterniflora in a Georgia salt marsh  

Microsoft Academic Search

Studies of the seasonal CO2 and water vapor exchange patterns of Juncus roemerianus and Spartina alterniflora were conducted in an undisturbed marsh community on Sapelo Island, Georgia. Daily patterns of net photosynthesis, transpiration, leaf diffusive conductance and water-use efficiency in response to ambient conditions were monitored on intact, in situ plants. Net primary productivity was calculated from the daytime CO2

J. R. Giurgevich; E. L. Dunn

1982-01-01

270

Original article Tree canopy and herb layer transpiration in three Scots  

E-print Network

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

Paris-Sud XI, Université de

271

ForPeerReview Tree diversity enhances tree transpiration in a Panamanian  

E-print Network

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

Bermingham, Eldredge

272

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

E-print Network

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

Williams, David G.

273

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

E-print Network

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

Martin, Timothy

274

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

E-print Network

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

Niyogi, Dev

275

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

E-print Network

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

Pielke, Roger A.

276

Physiological tradeoffs in the parameterization of a model of canopy transpiration  

E-print Network

Physiological tradeoffs in the parameterization of a model of canopy transpiration D.S. Mackay a in modeling stomatal control of transpiration from a number of forest species. Measurements of sapflux canopy transpiration (EC) for five tree species from these stands. They consisted of conifers

Ewers, Brent E.

277

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

E-print Network

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

Texas at Arlington, University of

278

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

E-print Network

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

Guswa, Andrew J.

279

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

PubMed Central

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

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

2013-01-01

280

Metabolites from soil bacteria affect plant water relations  

Microsoft Academic Search

Water-soluble compounds move naturally in soil moisture toward roots of transpiring plants. To test for effects of rhizosphere food-web molecules on plants, low concentrations of common microbial products were supplied to bean (Phaseolus vulgaris L.) roots. Stomatal conductance and transpiration increased significantly (+20 to +30%, P ? 0.05) 42 h after 10 nM homoserine lactone (HL) was supplied to roots. Because transpiration

2003-01-01

281

Rates of molecular evolution and diversification in plants: chloroplast substitution rates correlate with species-richness in the Proteaceae  

PubMed Central

Background Many factors have been identified as correlates of the rate of molecular evolution, such as body size and generation length. Analysis of many molecular phylogenies has also revealed correlations between substitution rates and clade size, suggesting a link between rates of molecular evolution and the process of diversification. However, it is not known whether this relationship applies to all lineages and all sequences. Here, in order to investigate how widespread this phenomenon is, we investigate patterns of substitution in chloroplast genomes of the diverse angiosperm family Proteaceae. We used DNA sequences from six chloroplast genes (6278bp alignment with 62 taxa) to test for a correlation between diversification and the rate of substitutions. Results Using phylogenetically-independent sister pairs, we show that species-rich lineages of Proteaceae tend to have significantly higher chloroplast substitution rates, for both synonymous and non-synonymous substitutions. Conclusions We show that the rate of molecular evolution in chloroplast genomes is correlated with net diversification rates in this large plant family. We discuss the possible causes of this relationship, including molecular evolution driving diversification, speciation increasing the rate of substitutions, or a third factor causing an indirect link between molecular and diversification rates. The link between the synonymous substitution rate and clade size is consistent with a role for the mutation rate of chloroplasts driving the speed of reproductive isolation. We find no significant differences in the ratio of non-synonymous to synonymous substitutions between lineages differing in net diversification rate, therefore we detect no signal of population size changes or alteration in selection pressures that might be causing this relationship. PMID:23497266

2013-01-01

282

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

NASA Technical Reports Server (NTRS)

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.

Micklow, Gerald J.

1996-01-01

283

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

NASA Astrophysics Data System (ADS)

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.

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

2012-04-01

284

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

Microsoft Academic Search

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

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

285

Measured isoprene emission rates of plants in California landscapes: comparison to estimates from taxonomic relationships  

Microsoft Academic Search

Isoprene emission rates of 64 plant species found in California's urban and natural landscapes were measured using a dynamic flow-through chamber enclosure technique. Species were selected to provide data for previously unmeasured species and to test estimates of isoprene emission rates based upon taxonomic relationships developed for compilation of biogenic emission inventories as proposed by Benjamin et al. (1996, Atmospheric

John F. Karlik; Arthur M. Winer

2001-01-01

286

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

NASA Astrophysics Data System (ADS)

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

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

2010-05-01

287

Planting Rate and Date Rates are based on seed of normal size and good quality and normal seedbed. Actual rates used will vary widely, depending on seed cost, desired stand,  

E-print Network

, emerging ability, seed weight, seed germination, seedbed condition, depth of planting and planting71 103 Planting Rate and Date Rates are based on seed of normal size and good quality and normal seedbed. Actual rates used will vary widely, depending on seed cost, desired stand, expected mortality

Thomas, David D.

288

Transpiration as the Leak in a Carbon Factory: A Model of Self-Optimising Vegetation  

NASA Astrophysics Data System (ADS)

"Only now it occurred to me that plants are not water pumps but carbon factories" (Anonymous Hydrologist). When thinking of plants as `water pumps', we are led to the conclusion that vegetation would tend to maximise the total amount of transpiration while minimising the occurrence probability of periods without adequate water availability (`stress'). However, this does not do adequate justice to the fact that plants owe their existence to photosynthesis, and can thrive perfectly well even when the relative humidity of the air is very high and transpiration is almost negligible. In this paper, we present a model in which the maximisation of net CO2 uptake rather than maximisation of water use or minimisation of `stress' is assumed to be the driving force behind natural selection. Transpiration is the inevitable consequence of CO2 uptake from the atmosphere and water uptake from the soil incurs construction and maintenance costs of a root system, so that water use strategies become a consequence of the maximisation of net CO2 uptake and `stress' becomes an obsolete feature. We will demonstrate that a simple model based on ecological optimality is capable of reproducing some vegetation and water balance dynamics without any prior knowledge about the vegetation on a particular site. The model is based on a physical water balance model by Reggiani et al. (2000), an ecophysiological gas exchange and photosynthesis model (Cowan and Farquhar 1977; von Caemmerer 2000), and the hypothesis that natural selection leads to a vegetation type that optimally uses available resources to maximise its `net carbon profit' (the net tradeoff between carbon acquired by photosynthesis and carbon spent on maintenance of the organs involved in its uptake). While, at this early stage of its development, the site properties such as soil type and depth, topography and climate still have to be prescribed, the model creates the `optimal' dynamically adjusting vegetation for the particular site and calculates the water- and CO2- fluxes between soil, watershed boundaries, vegetation and atmosphere. Cowan, I. R. and G. D. Farquhar (1977). Stomatal Function in Relation to Leaf Metabolism and Environment. Integration of activity in the higher plant. D. H. Jennings. Cambridge, Cambridge University Press: 471-505. Reggiani, P., M. Sivapalan, et al. (2000). Conservation equations governing hillslope responses: Exploring the physical basis of water balance. Water Resources Research 36(7): 1845-1863. von Caemmerer, S. (2000). Biochemical Models of Leaf Photosynthesis. Collingwood, CSIRO Publishing.

Sivapalan, M.; Schymanski, S. J.; Roderick, M. L.

2005-12-01

289

Effect, uptake and disposition of nitrobenzene in several terrestrial plants  

SciTech Connect

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.

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

1990-01-01

290

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

PubMed

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

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

2010-03-01

291

Transpiration cooled electrodes and insulators for MHD generators  

DOEpatents

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.

Hoover, Jr., Delmer Q. (Churchill Boro, PA)

1981-01-01

292

The effect of gravity on surface temperature and net photosynthetic rate of plant leaves  

Microsoft Academic Search

To clarify the effects of gravity on heat\\/gas exchange between plant leaves and the ambient air, the leaf temperatures and net photosynthetic rates of plant leaves were evaluated at 0.01, 1.0, 1.5 and 2.0 G of 20 seconds each during a parabolic airplane flight. Thermal images of leaves were captured using infrared thermography at an air temperature of 26 °C,

Y. Kitaya; M. Kawai; J. Tsuruyama; H. Takahashi; A. Tani; E. Goto; T. Saito; M. Kiyota

2001-01-01

293

Dispersal and colonisation of plants in lowland streams: success rates and bottlenecks  

Microsoft Academic Search

Plant dispersal and colonisation, including rates of dispersal, retention, colonisation and survival of dispersed propagules\\u000a (shoots and seeds), were studied in a 300-m stream reach in a macrophyte-rich lowland stream during one growing season. Relationships\\u000a between colonisation processes and simple flow parameters were tested. Each fortnight during a growing season, the number\\u000a of dispersed plant propagules and the number of

Tenna Riis

2008-01-01

294

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

PubMed Central

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

Young, Nelson D; dePamphilis, Claude W

2005-01-01

295

DSMC Simulation of thermal transpiration and accomodation pumps  

SciTech Connect

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.

Hudson, M.L.; Bartel, T.J.

1998-11-01

296

Transpiration of cottonwood\\/willow forest estimated from sap flux  

Microsoft Academic Search

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

Sean M. Schaeffer; David G. Williams; David C. Goodrich

2000-01-01

297

PGEN: an integrated model of leaf photosynthesis, transpiration, and conductance  

Microsoft Academic Search

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

A. D. Friend

1995-01-01

298

Study of deposition control using transpiration. Technical progress report  

SciTech Connect

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 introducting 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 particles sizes under conditions simulating gas turbine conditions.

Louis, J.F.; Kozlu, H.

1984-10-01

299

Study of deposition control using transpiration. Technical progress report  

SciTech Connect

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.

Louis, J.F.; Kozlu, H.

1986-03-01

300

Study of deposition control using transpiration. Technical progress report  

SciTech Connect

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.

Louis, J.F.; Kozlu, H.

1984-11-01

301

Study of deposition control using transpiration. Technical progress report  

SciTech Connect

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.

Louis, J.F.; Kozlu, H.

1985-01-01

302

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

Microsoft Academic Search

  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

Carrie-Ann Whittle; Mark O. Johnston

2003-01-01

303

Bacterial secondary production on vascular plant detritus: relationships to detritus composition and degradation rate.  

PubMed Central

Bacterial production at the expense of vascular plant detritus was measured for three emergent plant species (Juncus effusus, Panicum hemitomon, and Typha latifolia) degrading in the littoral zone of a thermally impacted lake. Bacterial secondary production, measured as tritiated thymidine incorporation into DNA, ranged from 0.01 to 0.81 microgram of bacterial C mg of detritus-1 day-1. The three plant species differed with respect to the amount of bacterial productivity they supported per milligram of detritus, in accordance with the predicted biodegradability of the plant material based on initial nitrogen content, lignin content, and C/N ratio. Bacterial production also varied throughout the 22 weeks of in situ decomposition and was positively related to the nitrogen content and lignin content of the remaining detritus, as well as to the temperature of the lake water. Over time, production was negatively related to the C/N ratio and cellulose content of the degrading plant material. Bacterial production on degrading plant material was also calculated on the basis of plant surface area and ranged from 0.17 to 1.98 micrograms of bacterial C cm-2 day-1. Surface area-based calculations did not correlate well with either initial plant composition or changing composition of the remaining detritus during decomposition. The rate of bacterial detritus degradation, calculated from measured production of surface-attached bacteria, was much lower than the actual rate of weight loss of plant material. This discrepancy may be attributable to the importance of nonbacterial organisms in the degradation and loss of plant material from litterbags or to the microbially mediated solubilization of particulate material prior to bacterial utilization, or both. PMID:2802603

Moran, M A; Hodson, R E

1989-01-01

304

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

Microsoft Academic Search

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

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

2005-01-01

305

Somatic deleterious mutation rate in a woody plant: estimation from phenotypic data  

PubMed Central

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

Bobiwash, K; Schultz, S T; Schoen, D J

2013-01-01

306

Coal flow aids reduce coke plant operating costs and improve production rates  

SciTech Connect

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.

Bedard, R.A.; Bradacs, D.J.; Kluck, R.W.; Roe, D.C.; Ventresca, B.P.

2005-06-01

307

The Correlation of Evolutionary Rate with Pathway Position in Plant Terpenoid Biosynthesis  

E-print Network

. However, few clear examples of this trend in evolutionary rate variation exist. We examined whether genes involved in plant terpenoid biosynthesis exhibit such a pattern, using data for 40 genes from five fully, signaling, and development) have shown that network properties such as node connectivity and centrality

Rieseberg, Loren

308

Developmental changes in plant resistance to water flow in Pisum sativum (L.)  

Microsoft Academic Search

Soil and plant resistance to water flow under field conditions in pea (Pisum sativum L.) plants were measured at six ages. Transpiration flux, leaf and soil water potentials were used to calculate the total resistance to water flow using the Ohm's law analogy. Plant resistance was estimated from the slope of the water potential difference (??) vs. transpiration (Q) relationship.

Celestino Ruggiero; Stefania De Pascale; Giovanna Angelino; Albino Maggio

2003-01-01

309

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

PubMed Central

Background An understanding of the evolution of potential signals from plants to the predators of their herbivores may provide exciting examples of co-evolution among multiple trophic levels. Understanding the mechanism behind the attraction of predators to plants is crucial to conclusions about co-evolution. For example, insectivorous birds are attracted to herbivore-damaged trees without seeing the herbivores or the defoliated parts, but it is not known whether birds use cues from herbivore-damaged plants with a specific adaptation of plants for this purpose. Methodology We examined whether signals from damaged trees attract avian predators in the wild and whether birds could use volatile organic compound (VOC) emissions or net photosynthesis of leaves as cues to detect herbivore-rich trees. We conducted a field experiment with mountain birches (Betula pubescens ssp. czerepanovii), their main herbivore (Epirrita autumnata) and insectivorous birds. Half of the trees had herbivore larvae defoliating trees hidden inside branch bags and half had empty bags as controls. We measured predation rate of birds towards artificial larvae on tree branches, and VOC emissions and net photosynthesis of leaves. Principal Findings and Significance The predation rate was higher in the herbivore trees than in the control trees. This confirms that birds use cues from trees to locate insect-rich trees in the wild. The herbivore trees had decreased photosynthesis and elevated emissions of many VOCs, which suggests that birds could use either one, or both, as cues. There was, however, large variation in how the VOC emission correlated with predation rate. Emissions of (E)-DMNT [(E)-4,8-dimethyl-1,3,7-nonatriene], ?-ocimene and linalool were positively correlated with predation rate, while those of highly inducible green leaf volatiles were not. These three VOCs are also involved in the attraction of insect parasitoids and predatory mites to herbivore-damaged plants, which suggests that plants may not have specific adaptations to signal only to birds. PMID:18665271

Mantyla, Elina; Alessio, Giorgio A.; Blande, James D.; Heijari, Juha; Holopainen, Jarmo K.; Laaksonen, Toni; Piirtola, Panu; Klemola, Tero

2008-01-01

310

Association between Residential Proximity to Fuel-Fired Power Plants and Hospitalization Rate for Respiratory Diseases  

PubMed Central

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

Liu, Xiaopeng; Lessner, Lawrence

2012-01-01

311

Ozone uptake and effects on transpiration, net photosynthesis, and dark respiration in Scots pine. [Pinus sylvestris L  

SciTech Connect

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.

Skaerby, L.; Troeng, E.; Bostroem, C.

1987-09-01

312

Changes in vascular and transpiration flows affect the seasonal and daily growth of kiwifruit (Actinidia deliciosa) berry  

PubMed Central

Background and Aims The kiwifruit berry is characterized by an early stage of rapid growth, followed by a relatively long stage of slow increase in size. Vascular and transpiration flows are the main processes through which water and carbon enter/exit the fruit, determining the daily and seasonal changes in fruit size. This work investigates the biophysical mechanisms underpinning the change in fruit growth rate during the season. Methods The daily patterns of phloem, xylem and transpiration in/outflows have been determined at several stages of kiwifruit development, during two seasons. The different flows were quantified by comparing the diurnal patterns of diameter change of fruit, which were then girdled and subsequently detached while measurements continued. The diurnal courses of leaf and stem water potential and of fruit pressure potential were also monitored at different times during the season. Key Results Xylem and transpiration flows were high during the first period of rapid volume growth and sharply decreased with fruit development. Specific phloem import was lower and gradually decreased during the season, whereas it remained constant at whole-fruit level, in accordance with fruit dry matter gain. On a daily basis, transpiration always responded to vapour pressure deficit and contributed to the daily reduction of fruit hydrostatic pressure. Xylem flow was positively related to stem-to-fruit pressure potential gradient during the first but not the last part of the season, when xylem conductivity appeared to be reduced. Conclusions The fruit growth model adopted by this species changes during the season due to anatomical modifications in the fruit features. PMID:20382641

Morandi, Brunella; Manfrini, Luigi; Losciale, Pasquale; Zibordi, Marco; Corelli Grappadelli, Luca

2010-01-01

313

Microclimatological and Physiological Controls of Stomatal Conductance and Transpiration of Co-Occurring Seedlings with Varying Shade Tolerance  

NASA Astrophysics Data System (ADS)

Forest ecosystems provide a significant portion of fresh water to the hydrologic cycle through transpiration, the majority of which is supplied by saplings and mature trees. However, a smaller, yet measurable, proportion is also supplied by seedlings. The contribution of seedlings is dependent upon physiological characteristics of the species, whose range of habitat is ultimately controlled by microclimate. The objectives of this study were to (1) observe meteorological conditions of two forest microlimates and (2) assess the intra- and interspecific stomatal conductance and transpiration responses of naturally occurring seedlings of varying shade tolerance. Naturally established seedlings in a deciduous forest understory and an adjacent clearing were monitored throughout the 2008 growing season in southeastern Pennsylvania (39°49'N, 75°43'W). Clear spatial and temporal trends of stomatal conductance and transpiration were observed throughout this study. The understory microclimate conditions overall had a lower degree of variability and had consistently lower mean quantum flux density, air temperature, vapor pressure deficit, volumetric water content, and soil temperature than the clearing plot. Shade tolerant understory seedlings (Fagus grandifolia Ehrh. (American beech) and Prunus serotina L. (black cherry)) had significantly lower mean monthly rates of water loss (p = 0.05) than shade intolerant clearing seedlings (P. serotina and Liriodendron tulipifera L. (yellow poplar)). Additionally, water loss by shade grown P. serotina was significantly lower (p = 0.05) than by sun grown P. serotina. Significant intraspecific responses (p = 0.05) were also observed on a monthly basis, with the exception of L. tulipifera. These findings indicate that physiological differences, specifically shade tolerance, play an important role in determining rates of stomatal conductance and transpiration in tree seedlings. To a lesser degree, microclimate variability was also shown to influence rates stomatal conductance and transpiration (3.6% and 7.8% in the understory and 8.2% and 23.2% in the clearing, respectively). Field validations are critical to developing better models and forest management strategies and therefore the results of this study may serve to validate those obtained in previous studies conducted largely under controlled conditions.

Siegert, C. M.; Levia, D. F.

2010-12-01

314

Evaluation of transpiration in a Douglas-fir stand by means of sap flow measurements  

Microsoft Academic Search

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

A. GRANIER

1987-01-01

315

Crown conductance and tree and stand transpiration in a second-growth Abies amabilis  

E-print Network

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

Martin, Timothy

316

Loss rate of NO y from a power plant plume based on aircraft measurements  

NASA Astrophysics Data System (ADS)

This study was motivated by the recent work of Buhr et al. [1996] which reported losses of NOy from large power plant plumes as high as 0.25 hour-1, much higher than generally accepted values. If true, conclusions pertaining to the efficiency of ozone and nitrate production in the lower troposphere would need major revisions. The results of Buhr et al. were based on aircraft measurements in four TVA (Tennessee Valley Authority) power plant plumes on July 7, 1995, as part of the Nashville/Middle Tennessee Ozone Study, a measurement program of the Southern Oxidants Study (SOS), whereas the results reported in this paper are also based on measurements made in the same SOS study aboard another instrumented aircraft (the TVA helicopter), in plumes of one of these power plants (the Cumberland Steam Plant in northwestern Tennessee) during five different days in 1994 and 1995. Between the 1994 and 1995 sampling periods, emissions of SO2 at the Cumberland plant were reduced by nearly 95% by installation of scrubbers. Our data from the one 1994 day show that the ratio of excess SO2 to NOy, in the plume core increased significantly with plume age, indicating a potentially high differential loss rate of NOy (excess loss of NOy relative to SO2) of about 0.12 hour-1. However, results based on the larger 1995 data set indicate a low differential NOy loss rate of only 0.00±0.03 hour-1, consistent with accepted low loss rates. Because the SOS-Nashville/Middle Tennessee Ozone Study was not specifically designed to explore the NOy loss issue, the question of NOy loss rates in plumes is not currently resolved and additional focused field studies are needed.

Gillani, N. V.; Luria, M.; Valente, R. J.; Tanner, R. L.; Imhoff, R. E.; Meagher, J. F.

1998-09-01

317

A contribution of groundwater to Mojave Desert shrub transpiration  

SciTech Connect

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.

Hunter, R.B.

1988-12-31

318

Slug flow in horizontal pipes with transpiration at the wall  

NASA Astrophysics Data System (ADS)

The present work investigates the behaviour of slug flows in horizontal pipes with a permeable wall. Measurements of pressure drop and of local velocity are given for nine different flow conditions. The liquid phase velocity was measured with laser Doppler anemometry. Single-phase data are compared with the results of other authors. The influence of flow transpiration and of roughness on the features of slug flows is shown to be pronounced. A Shadow Sizer system coupled with Particle Image Velocimetry is used to account for the properties of the slug cell.

Loureiro, J. B. R.; Silva Freire, A. P.

2011-12-01

319

Transpiration and hydraulic strategies in a piñon-juniper woodland.  

PubMed

Anthropogenic climate change is likely to alter the patterns of moisture availability globally. The consequences of these changes on species distributions and ecosystem function are largely unknown, but possibly predictable based on key ecophysiological differences among currently coexisting species. In this study, we examined the environmental and biological controls on transpiration from a piñon-juniper (Pinus edulis-Juniperus osteosperma) woodland in southern Utah, USA. The potential for climate-change-associated shifts in moisture inputs could play a critical role in influencing the relative vulnerabilities of piñons and junipers to drought and affecting management decisions regarding the persistence of this dominant landscape type in the Intermountain West. We aimed to assess the sensitivity of this woodland to seasonal variations in moisture and to mechanistically explain the hydraulic strategies of P. edulis and J. osteosperma through the use of a hydraulic transport model. Transpiration from the woodland was highly sensitive to variations in seasonal moisture inputs. There were two distinct seasonal pulses of transpiration: a reliable spring pulse supplied by winter-derived precipitation, and a highly variable summer pulse supplied by monsoonal precipitation. Transpiration of P. edulis and J. osteosperma was well predicted by a mechanistic hydraulic transport model (R2 = 0.83 and 0.92, respectively). Our hydraulic model indicated that isohydric regulation of water potential in P. edulis minimized xylem cavitation during drought, which facilitated drought recovery (94% of pre-drought water uptake) but came at the cost of cessation of gas exchange for potentially extended periods. In contrast, the anisohydric J. osteosperma was able to maintain gas exchange at lower water potentials than P. edulis but experienced greater cavitation over the drought and showed a lesser degree of post-drought recovery (55% of pre-drought uptake). As a result, these species should be differentially affected by shifts in the frequency, duration, and intensity of drought. Our results highlight the sensitivity of this woodland type to potential climate-change-associated shifts in seasonal moisture patterns and demonstrate the utility of mechanistic hydraulic models in explaining differential responses of coexisting species to drought. PMID:18536252

West, A G; Hultine, K R; Sperry, J S; Bush, S E; Ehleringer, J R

2008-06-01

320

Control and Augmentation of Passive Porosity through Transpiration Control  

NASA Technical Reports Server (NTRS)

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.

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

1999-01-01

321

Thermal/structural analysis of a transpiration cooled nozzle  

NASA Technical Reports Server (NTRS)

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.

Gregory, Peyton B.; Thompson, Jon E.; Babcock, Dale A.; Gray, Carl E., Jr.; Mouring, Chris A.

1992-01-01

322

A study of the distribution and production rates of ethylene within the cotton plant  

E-print Network

) to ti". e top of the plant (younge t tis- sue) occurs in the ?seen b eget. tive cotton p' ant. trend occurred in +he product'on rates o. errtirc leav as well as leaf parts and also occurred in the in. err;al levels ol e ethylene in ti e en+inc leaf a... shown to b. . pz oduced by a ":ride var iety of vegetative ti, sue (28, 40, 41, 55), flowers (6, 14), and fruits (15, 16, 2G, 21). Possible Hormonal Roles of' Ethylene The first evidence that ethylene might be a plant hormone was presented in 1935...

McAfee, James A

2012-06-07

323

The effect of gravity on surface temperature and net photosynthetic rate of plant leaves  

NASA Astrophysics Data System (ADS)

To clarify the effects of gravity on heat/gas exchange between plant leaves and the ambient air, the leaf temperatures and net photosynthetic rates of plant leaves were evaluated at 0.01, 1.0, 1.5 and 2.0 G of 20 seconds each during a parabolic airplane flight. Thermal images of leaves were captured using infrared thermography at an air temperature of 26 °C, a relative humidity of 15 % and an irradiance of 260 W m -2. The net photosynthetic rates were determined by using a chamber method with an infrared gas analyzer at an air temperature of 20 °C, a relative humidity of 50 % and a photosynthetic photon flux of 0.5 mmol m -2 s -1. The mean leaf temperature increased by 1 °C and the net photosynthetic rate decreased by 13 % with decreasing gravity levels from 1.0 to 0.01 G. The leaf temperature decreased by 0.5 °C and the net photosynthetic rate increased by 7 % with increasing gravity levels from 1.0 to 2.0 G. Heat/gas exchanges between leaves and the ambient air were more retarded at lower gravity levels. A restricted free air convection under microgravity conditions in space would limit plant growth by retarding heat and gas exchanges between leaves and the ambient air.

Kitaya, Y.; Kawai, M.; Tsuruyama, J.; Takahashi, H.; Tani, A.; Goto, E.; Saito, T.; Kiyota, M.

2001-01-01

324

Transpiration cooling in the locality of a transverse fuel jet for supersonic combustors  

NASA Technical Reports Server (NTRS)

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.

Northam, G. Burton; Capriotti, Diego P.; Byington, Carl S.

1990-01-01

325

Improved growth, productivity and quality of tomato (Solanum lycopersicum L.) plants through application of shikimic acid.  

PubMed

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

Al-Amri, Salem M

2013-10-01

326

Improved growth, productivity and quality of tomato (Solanum lycopersicum L.) plants through application of shikimic acid  

PubMed Central

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

Al-Amri, Salem M.

2013-01-01

327

Shock/shock interference on a transpiration cooled hemispherical model  

NASA Technical Reports Server (NTRS)

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.

Nowak, Robert J.; Wieting, Allan R.; Holden, Michael S.

1990-01-01

328

Turbulence in the Core of a Transpired Channel  

SciTech Connect

Flow in a fully transpired channel is examined using Particle-Image Velocimetry(PIV) to investigate the effect of stream-wise injection length scales on the core flow mean and turbulence properties. Instantaneous velocity fields are captured in a stream-wise - wall-normal plane at four different stream-wise locations (x/h=7,15,25,35) and four different porous surfaces: 3.175-mm, 4.7625-mm, 6.35-mm, 9.525-mm honeycombs. The 3.175-mm and 4.7625-mm honeycombs create smaller fluctuations in the wall-normal injection velocity and result in lower core turbulence. As a result, their mean flow profiles follow the inviscid Culick solution for a considerable distance downstream. The 6.35-mm and 9.525-mm honeycombs create higher wall-normal perturbations which get strongly amplified by the mean strain field resulting in a higher turbulence intensity downstream. As a result, their mean flow profiles deviate significantly from the Culick solution. It is found that the turbulence is profoundly affected by the mean details of the wall boundary conditions. In addition, for the first time, a database of turbulence statistics along with the complete boundary conditions (including the wall dynamic impedance) is provided to completely characterize the flow in a fully transpired channel.

Balamkumar, B J.; Adrian, Ronald J.; Deng, Zhiqun

2005-08-24

329

Extinction rate estimates for plant populations in revisitation studies: Importance of detectability  

USGS Publications Warehouse

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.

Kery, M.

2004-01-01

330

Evaporation, transpiration, and ecosystem water use efficiency in a multi-annual sugarcane production system in Hawai'i, USA  

NASA Astrophysics Data System (ADS)

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.

Anderson, R. G.; Tirado-corbala, R.; Wang, D.; Ayars, J. E.

2013-12-01

331

Photosynthesis in intact leaves of C 3 plants: Physics, physiology and rate limitations  

Microsoft Academic Search

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

Thomas D. Sharkey

1985-01-01

332

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

E-print Network

Jason E. Sawyer Don M. Vietor Head of Department, David D. Baltensperger December 2007 Major Subject: Agronomy iii ABSTRACT Impact of Planting Date and Seeding Rate on Grain and Forage Yields of Wheat.... v ACKNOWLEDGEMENTS I would like to gratefully acknowledge the help of those individuals who made this research possible. First, to my committee members, Dr. Todd Baughman, Dr. Jason Sawyer, and Dr. Don Vietor, I extend many thanks to you...

Shaffer, Oliver Jacob

2009-05-15

333

Consequences of light absorptance in calculating electron transport rate of desert and succulent plants  

Microsoft Academic Search

The proportional light absorptance by photosynthetic tissue (?) is used with chlorophyll (Chl) fluorescence methods to calculate\\u000a electron transport rate (ETR). Although a value of ? of 0.84 is often used as a standard for calculating ETR, many succulent\\u000a plant species and species with crassulacean acid metabolism (CAM) have photosynthetic tissues that vary greatly in color or\\u000a are highly reflective,

J. A. Stemke; L. S. Santiago

334

Numerical reconstruction of high dose rate zones due to the Fukushima Daiichi Nuclear Power Plant accident  

Microsoft Academic Search

To understand how the high dose rate zones were created during the Fukushima Daiichi Nuclear Power Plant (FNPP1) accident on March 2011, the atmospheric dispersion of radionuclides during the period from 15 to 17 March was reproduced by using a computer-based nuclear emergency response system, WSPEEDI-II. With use of limited environmental monitoring data, prediction accuracy of meteorological and radiological fields

Genki Katata; Hiroaki Terada; Haruyasu Nagai; Masamichi Chino

335

Response of Popcorn (Zea mays everta) to Nitrogen Rates and Plant Densities  

Microsoft Academic Search

The objective of this study was to evaluate grain yield and yield components of popcorn with different nitrogen rates and plant densities. Field studies were conducted in 1995 and 1996 at Kazova Plain in Tokat. The experiment was designed in a randomized-complete-block design with a split-plot arrangement with three replications. The treatments comprised six levels of nitrogen (0, 50, 100,

Sabri GÖKMEN; Özer SENCAR; Mehmet Ali SAK

336

Trade-Offs between the Metabolic Rate and Population Density of Plants  

PubMed Central

The energetic equivalence rule, which is based on a combination of metabolic theory and the self-thinning rule, is one of the fundamental laws of nature. However, there is a progressively increasing body of evidence that scaling relationships of metabolic rate vs. body mass and population density vs. body mass are variable and deviate from their respective theoretical values of 3/4 and ?3/4 or ?2/3. These findings questioned the previous hypotheses of energetic equivalence rule in plants. Here we examined the allometric relationships between photosynthetic mass (Mp) or leaf mass (ML) vs. body mass (?); population density vs. body mass (?); and leaf mass vs. population density, for desert shrubs, trees, and herbaceous plants, respectively. As expected, the allometric relationships for both photosynthetic mass (i.e. metabolic rate) and population density varied with the environmental conditions. However, the ratio between the two exponents was ?1 (i.e. ?/??=??1) and followed the trade-off principle when local resources were limited. Our results demonstrate for the first time that the energetic equivalence rule of plants is based on trade-offs between the variable metabolic rate and population density rather than their constant allometric exponents. PMID:18350139

Deng, Jian-Ming; Li, Tao; Wang, Gen-Xuan; Liu, Jing; Yu, Ze-Long; Zhao, Chang-Ming; Ji, Ming-Fei; Zhang, Qiang; Liu, Jian-quan

2008-01-01

337

Enhanced IGCC regulatory control and coordinated plant-wide control strategies for improving power ramp rates  

SciTech Connect

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.

Mahapatra, P.; Zitney, S.

2012-01-01

338

Supplementary documentation for an Environmental Impact Statement regarding the Pantex Plant: a comparison of county and state cancer mortality rates  

Microsoft Academic Search

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

L. D. Wiggs; G. S. Wilkinson; G. L. Tietjen; J. F. Acquavella

1982-01-01

339

Experimental and numerical studies on the heterogeneity of crop transpiration in a plastic tunnel  

Microsoft Academic Search

The heterogeneity of crop transpiration is important to clearly understand the microclimate mechanisms and to efficiently handle the water resource in greenhouses. A computational fluid dynamic software (cfd2000) was used to study the climate and crop transpiration distributions in a 22×8 m2 plastic tunnel situated in Avignon, France, together with a global solar radiation model and a crop heat exchange

T. Boulard; S. Wang

2002-01-01

340

A Dynamic, Architectural Plant Model Simulating Resource?dependent Growth  

PubMed Central

• Background and Aims Physiological and architectural plant models have originally been developed for different purposes and therefore have little in common, thus making combined applications difficult. There is, however, an increasing demand for crop models that simulate the genetic and resource?dependent variability of plant geometry and architecture, because man is increasingly able to transform plant production systems through combined genetic and environmental engineering. • Model GREENLAB is presented, a mathematical plant model that simulates interactions between plant structure and function. Dual?scale automaton is used to simulate plant organogenesis from germination to maturity on the basis of organogenetic growth cycles that have constant thermal time. Plant fresh biomass production is computed from transpiration, assuming transpiration efficiency to be constant and atmospheric demand to be the driving force, under non?limiting water supply. The fresh biomass is then distributed among expanding organs according to their relative demand. Demand for organ growth is estimated from allometric relationships (e.g. leaf surface to weight ratios) and kinetics of potential growth rate for each organ type. These are obtained through parameter optimization against empirical, morphological data sets by running the model in inverted mode. Potential growth rates are then used as estimates of relative sink strength in the model. These and other ‘hidden’ plant parameters are calibrated using the non?linear, least?square method. • Key Results and Conclusions The model reproduced accurately the dynamics of plant growth, architecture and geometry of various annual and woody plants, enabling 3D visualization. It was also able to simulate the variability of leaf size on the plant and compensatory growth following pruning, as a result of internal competition for resources. The potential of the model’s underlying concepts to predict the plant’s phenotypic plasticity is discussed. PMID:15056562

YAN, HONG?PING; KANG, MENG ZHEN; DE REFFYE, PHILIPPE; DINGKUHN, MICHAEL

2004-01-01

341

Island radiation on a continental scale: Exceptional rates of plant diversification after uplift of the Andes  

PubMed Central

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

Hughes, Colin; Eastwood, Ruth

2006-01-01

342

Fire and grazing influences on rates of riparian woody plant expansion along grassland streams.  

PubMed

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

Veach, Allison M; Dodds, Walter K; Skibbe, Adam

2014-01-01

343

Differentiating transpiration from evaporation in seasonal agricultural wetlands and the link to advective fluxes in the root zone.  

PubMed

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 flow rates and tracer concentrations at wetland inflows and outflows. We used two ideal reactor model solutions, a continuous flow stirred 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 non-ideal agricultural wetlands in which check ponds are in series. Using a flux model, 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 biogeochemical mechanisms 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. PMID:24296049

Bachand, P A M; Bachand, S; Fleck, J; Anderson, F; Windham-Myers, L

2014-06-15

344

Helianthus Nighttime Conductance and Transpiration Respond to Soil Water But Not Nutrient Availability1[W][OA  

PubMed Central

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

Howard, Ava R.; Donovan, Lisa A.

2007-01-01

345

Species differences in evergreen tree transpiration at daily, seasonal, and interannual timescales  

NASA Astrophysics Data System (ADS)

Mediterranean climates have rainy winter and dry summer seasons, so the season of water availability (winter) is out of phase with the season of light availability and atmospheric demand (summer). In this study, we investigate the seasonality of tree transpiration in a Mediterranean climate, using observations from a small (8000 m2), forested, steep (~35 degree) hillslope at the UC Angelo Reserve, in the northern California Coast Range. The site is instrumented with over 850 sensors transmitting hydrologic and meteorological data at less than 30-minute intervals. Here, we analyze four years of high-frequency measurements from 45 sap flow sensors in 30 trees, six depth profiles of soil moisture measured by TDR, and spatially distributed measurements of air temperature, relative humidity, solar radiation, and other meteorological variables. The sap flow measurements show a difference in transpiration seasonality between common California Coast Range evergreen tree species. Douglas firs (Pseudotsuga menziesii) maintain significant transpiration through the winter rainy season and transpire maximally in the spring, but Douglas fir transpiration declines sharply in the summer dry season. Madrones (Arbutus menziesii), in contrast, transpire maximally in the summer dry season. The seasonal patterns are quantified using principal component analysis. Nonlinear regressions against environmental variables show that the difference in transpiration seasonality arises from different sensitivities to atmospheric demand (VPD) and root-zone moisture. The different sensitivities to VPD and root-zone moisture cause species differences not just in seasonal patterns, but also in high temporal frequency (daily to weekly) variability of transpiration. We also contrast the interannual variability of dry season transpiration among the different species, and show that precipitation above a threshold triggers a Douglas fir response. Finally, we use a simple 1-D model of the atmospheric boundary layer to estimate the effects of species differences in transpiration on atmospheric boundary layer temperature and humidity.

Link, P.; Simonin, K. A.; Oshun, J.; Dietrich, W.; Dawson, T. E.; Fung, I.

2012-12-01

346

Effects of plant genotype and insect dispersal rate on the population dynamics of a forest pest.  

PubMed

It has been shown that plant genotype can strongly affect not only individual herbivore performance, but also community composition and ecosystem function. Few studies, however, have addressed how plant genotype affects herbivore population dynamics. In this paper, we used a simulation modeling approach to ask how the genetic composition of a forest influences pest outbreak dynamics, using the example of aspen (Populus tremuloides) and forest tent caterpillars (FTC; Malacosoma disstria). Specifically, we examined how plant genotype, the relative size of genotypic patches, and the rate of insect dispersal between them, affect the frequency, amplitude, and duration of outbreaks. We found that coupling two different genotypes does not necessarily result in an averaging of insect dynamics. Instead, depending on the ratio of patch sizes, when dispersal rates are moderate, outbreaks in the two-genotype case may be more or less severe than in forests of either genotype alone. Thresholds for different dynamic behaviors were similar for all genotypic combinations. Thus, the qualitative behavior of a stand of two different genotypes can be predicted based on the response of the insect to each genotype, the relative sizes of the two patches, and the scale of insect dispersal. PMID:24597225

Moran, Emily V; Bewick, Sharon; Cobbold, Christina A

2013-12-01

347

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

PubMed

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

James, J J; Richards, J H

2005-08-01

348

Labile soil carbon inputs mediate the soil microbial community composition and plant residue decomposition rates  

SciTech Connect

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.

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

349

Thermal simulation and economic assessment of unglazed transpired collector systems  

SciTech Connect

Unglazed transpired collectors (UTCs) have recently emerged as a new solar air heating technology. They are relatively inexpensive, efficient, and particularly suited to applications in which a high outdoor air requirement must be met. A TRNSYS model has been created for UTC systems. Annual simulations are performed for several representative buildings. The statewide economic potential of UTC systems is assessed for Wisconsin. UTC systems on existing buildings are competitive with electric heating systems but not with gas or oil heating. Electric heating is not widely used in most buildings that are well-suited for UTC systems, with the exception of large apartment buildings. Therefore, there is no significant statewide economic potential for retrofit of UTC systems on existing buildings except in the residential sector. However, UTC systems are cost effective for new buildings because their low first cost allows them to compete with gas and oil heating.

Summers, D.N.; Mitchell, J.W.; Klein, S.A.; Beckman, W.A.

1996-10-01

350

A stomatal optimization theory to describe the effects of atmospheric CO2 on leaf photosynthesis and transpiration  

E-print Network

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

Katul, Gabriel

351

Ptant, Cett and Environment (1997) 20,1242-1252 Control of transpiration from the upper canopy of a tropicai  

E-print Network

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

Holbrook, N. Michele

352

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

E-print Network

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

Bermingham, Eldredge

353

Agricultural and Forest Meteorology 105 (2000) 257270 Transpiration of cottonwood/willow forest estimated from sap flux  

E-print Network

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

Williams, David G.

354

Controls on transpiration in a semiarid riparian cottonwood forest Rico M. Gazal a,*, Russell L. Scott b  

E-print Network

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

Williams, David G.

355

Rates of conversion of sulfur dioxide to sulfate in a scrubbed power plant plume.  

PubMed

The rate of conversion of SO2 to SO4(2-) was re-estimated from measurements made in the plume of the Cumberland power plant, located on the Cumberland River in north-central Tennessee, after installation of flue gas desulfurization (FGD) scrubbers for SO2 removal in 1994. The ratio of SO2 to NOy emissions into the plume has been reduced to approximately 0.1, compared with a prescrubber value of approximately 2. To determine whether the SO2 emissions reduction has correspondingly reduced plume-generated particulate SO4(2-) production, we have compared the rates of conversion before and after scrubber installation. The prescrubber estimates were developed from measurements made during the Tennessee Plume Study conducted in the late 1970s. The postscrubber estimates are based upon two series of research flights in the summers of 1998 and 1999. During two of these flights, the Cumberland plume did not mix with adjacent power plant plumes, enabling rate constants for conversion to be estimated from samples taken in the plume at three downwind distances. Dry deposition losses and the fact the fact that SO2 is no longer in large excess compared with SO4(2-) have been taken into account, and an upper limit for the conversion rate constant was re-estimated based on plume excess aerosol volume. The estimated upper limit values are 0.069 hr(-1) and 0.034 hr(-1) for the 1998 and 1999 data, respectively. The 1999 rate is comparable with earlier values for nonscrubbed plumes, and although the 1998 upper limit value is higher than expected, these estimates do not provide strong evidence for deviation from a linear relationship between SO2 emissions and SO4(2-) formation. PMID:11686244

Luria, M; Imhoff, R E; Valente, R J; Parkhurst, W J; Tanner, R L

2001-10-01

356

Variation in decomposition rates in the fynbos biome, South Africa: the role of plant species and plant stoichiometry.  

PubMed

Previous studies in the fynbos biome of the Western Cape, South Africa, have suggested that biological decomposition rates in the fynbos vegetation type, on poor soils, may be so low that fire is the main factor contributing to litter breakdown and nutrient release. However, the fynbos biome also comprises vegetation types on more fertile soils, such as the renosterveld. The latter is defined by the shrub Elytropappus rhinocerotis, while the shrub Galenia africana may become dominant in overgrazed areas. We examined decomposition of litter of these two species and the geophyte Watsonia borbonica in patches of renosterveld in an agricultural landscape. In particular, we sought to understand how plant species identity affects litter decomposition rates, especially through variation in litter stoichiometry. Decomposition (organic matter mass loss) varied greatly among the species, and was related to litter N and P content. G. africana, with highest nutrient content, lost 65% of its original mass after 180 days, while E. rhinocerotis had lost ca. 30%, and the very nutrient poor W. borbonica <10%. Litter placed under G. africana decomposed slightly faster than when placed under E. rhinocerotis. Over the course of the experiment, G. africana and E. rhinocerotis lost N and P, while W. borbonica showed strong accumulation of these elements. Decomposition rates of G. africana and E. rhinocerotis were substantially higher than those previously reported from fynbos vegetation, and variation among the species investigated was considerable. Our results suggest that fire may not always be the main factor contributing to litter breakdown and nutrient release in the fynbos biome. Thus, biological decomposition has likely been underestimated and, along with small-scale variation in ecosystem processes, would repay further study. PMID:20827492

Bengtsson, Jan; Janion, Charlene; Chown, Steven L; Leinaas, Hans Petter

2011-01-01

357

Variation in decomposition rates in the fynbos biome, South Africa: the role of plant species and plant stoichiometry  

PubMed Central

Previous studies in the fynbos biome of the Western Cape, South Africa, have suggested that biological decomposition rates in the fynbos vegetation type, on poor soils, may be so low that fire is the main factor contributing to litter breakdown and nutrient release. However, the fynbos biome also comprises vegetation types on more fertile soils, such as the renosterveld. The latter is defined by the shrub Elytropappus rhinocerotis, while the shrub Galenia africana may become dominant in overgrazed areas. We examined decomposition of litter of these two species and the geophyte Watsonia borbonica in patches of renosterveld in an agricultural landscape. In particular, we sought to understand how plant species identity affects litter decomposition rates, especially through variation in litter stoichiometry. Decomposition (organic matter mass loss) varied greatly among the species, and was related to litter N and P content. G. africana, with highest nutrient content, lost 65% of its original mass after 180 days, while E. rhinocerotis had lost ca. 30%, and the very nutrient poor W. borbonica <10%. Litter placed under G. africana decomposed slightly faster than when placed under E. rhinocerotis. Over the course of the experiment, G. africana and E. rhinocerotis lost N and P, while W. borbonica showed strong accumulation of these elements. Decomposition rates of G. africana and E. rhinocerotis were substantially higher than those previously reported from fynbos vegetation, and variation among the species investigated was considerable. Our results suggest that fire may not always be the main factor contributing to litter breakdown and nutrient release in the fynbos biome. Thus, biological decomposition has likely been underestimated and, along with small-scale variation in ecosystem processes, would repay further study. Electronic supplementary material The online version of this article (doi:10.1007/s00442-010-1753-7) contains supplementary material, which is available to authorized users. PMID:20827492

Janion, Charlene; Chown, Steven L.; Leinaas, Hans Petter

2010-01-01

358

The oxygen isotopic compositions of silica phytoliths and plant water in grasses: implications for the study of paleoclimate  

NASA Astrophysics Data System (ADS)

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.

Webb, Elizabeth A.; Longstaffe, Frederick J.

2000-03-01

359

Regularization of Feedwater Flow Rate Evaluation for Venturi Meter Fouling Problem in Nuclear Power Plants  

SciTech Connect

Inferential sensing is a method that can be used to evaluate parameters of a physical system based on a set of measurements related to these parameters. The most common method of inferential sensing uses mathematical models to infer a parameter value from correlated sensor values. However, since inferential sensing is an inverse problem, it can produce inconsistent results due to minor perturbations in the data. This research shows that regularization can be used in inferential sensing to produce consistent results. Data from Florida Power Corporation's Crystal River nuclear power plant (NPP) are used to give an important example of monitoring NPP feedwater flow rate.

Gribok, Andrei V.; Attieh, Ibrahim K.; Hines, J. Wesley; Uhrig, Robert E. [University of Tennessee (United States)

2001-04-15

360

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

E-print Network

L?BP A 8 V a L ?BPA8B8 op A THERMAL METHOD FOR MEASURING THE RATE OF WATER MOVEMENT IN PLANTS A Dissertation By Morris Elkins Bloodworth Vao Submitted to the Graduate School of the Agricultural and Mechanical College of Texas in Partial... ??BLA? ? ? ? ? ? ?? ?B?8?8?A B? ??A8? o? ????A???????????? ?? ??? ?????????^pP ??^i?? ?????????????????????????? ?? p? ??B?8???8? ??? ???A???8?A?AoB? ? ? ? ? ?? ?? ^8?A ???o?oAo8? ? ????A ???o?B??8?A?? ?B?A?B? ? ? o A...

Bloodworth, Morris Elkins

2013-10-04

361

Heart rate response to industrial work at different outdoor temperatures with or without temperature control system at the plant  

Microsoft Academic Search

Different outdoor temperatures, the association between indoor temperature control at the workplace and working heart rates of industrial employees were evaluated. The subjects, 6,016 male and female employees in 21 industrial plants in Israel, were screened for cardiovascular risk factors between 1985–87 (The CORDIS Study). The data collected included resting heart rate, working heart rate (based on one hour ambulatory

E. KRISTAL-BONEH; G. HARARI; M. S. GREEN

1997-01-01

362

The University of Chicago Contemporary Evolution of Plant Growth Rate Following Experimental Removal of  

E-print Network

are credited with driving the evolutionary diversification of plant defensive strategies over macroevolutionary of the most popular theories of plant defense. Keywords: community genetics, eco-evolutionary interactions, her- bivory, plant competition, plant defenses, Rumex acetosa. Introduction Herbivores have fed

Miller, Thomas E.

363

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

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.

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

364

Characteristics of microbial volatile organic compound flux rates from soil and plant litter  

NASA Astrophysics Data System (ADS)

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.

Gray, C. M.; Fierer, N.

2013-12-01

365

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)

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.

Berryman, E.; Barnard, H. R.; Brooks, P. D.; Adams, H.; Burns, M. A.; Wilson, W.; Stielstra, C. M.

2013-12-01

366

Exploring the importance of within-canopy spatial temperature variation on transpiration predictions.  

PubMed

Models seldom consider the effect of leaf-level biochemical acclimation to temperature when scaling forest water use. Therefore, the dependence of transpiration on temperature acclimation was investigated at the within-crown scale in climatically contrasting genotypes of Acer rubrum L., cv. October Glory (OG) and Summer Red (SR). The effects of temperature acclimation on intracanopy gradients in transpiration over a range of realistic forest growth temperatures were also assessed by simulation. Physiological parameters were applied, with or without adjustment for temperature acclimation, to account for transpiration responses to growth temperature. Both types of parameterization were scaled up to stand transpiration (expressed per unit leaf area) with an individual tree model (MAESTRA) to assess how transpiration might be affected by spatial and temporal distributions of foliage properties. The MAESTRA model performed well, but its reproducibility was dependent on physiological parameters acclimated to daytime temperature. Concordance correlation coefficients between measured and predicted transpiration were higher (0.95 and 0.98 versus 0.87 and 0.96) when model parameters reflected acclimated growth temperature. In response to temperature increases, the southern genotype (SR) transpiration responded more than the northern (OG). Conditions of elevated long-term temperature acclimation further separate their transpiration differences. Results demonstrate the importance of accounting for leaf-level physiological adjustments that are sensitive to microclimate changes and the use of provenance-, ecotype-, and/or genotype-specific parameter sets, two components likely to improve the accuracy of site-level and ecosystem-level estimates of transpiration flux. PMID:19561047

Bauerle, William L; Bowden, Joseph D; Wang, G Geoff; Shahba, Mohamed A

2009-01-01

367

How do soil texture, plant community composition and earthworms affected the infiltration rate in a grassland plant diversity experiment depending on season?  

NASA Astrophysics Data System (ADS)

Background and aims: In this study we analyzed the influences of plant community characteristics, soil texture and earthworm presence on infiltration rates on a managed grassland plant diversity experiment assessing the role of biotic and abiotic factors on soil hydrology. Methods: We measured infiltration using a hood infiltrometer in subplots with ambient and reduced earthworm density (earthworm extraction) nested in plots of different plant species richness (1, 4, and 16), plant functional group number and composition (1 to 4; legumes, grasses, small herbs, tall herbs) in early summer (June) and autumn (September, October) 2011. Results: The presence of certain plant functional groups such as grasses and legumes influenced infiltration rates and this effect enhanced during the growing season. Infiltration was significantly higher in plots containing legumes than in plots without, and it was significantly lower in the presence of grasses than in their absence. In early summer, earthworm presence and biomass increased the infiltration rates, independently of plant species richness. In October, plant species richness only affected infiltration rates in reduced earthworm plots. At the end of the growing season earthworm populations were negatively influenced by grasses and positively by legumes. In September, infiltration rates were positive related to the proportion of finer grains. The correlation disappears when removing all plots containing legumes from the sample. For all measurements the infiltration rates decreases from early summer to autumn at the matric potentials at pressure zero and -0.02 m, but not for smaller macropores at matric potentials -0.04 and -0.06m. Conclusions: Considering infiltration rates as ecosystem function, this function will largely depend on the ecosystem composition and season, not on biodiversity per se. Our results indicate that biotic factors are of overriding influence for shaping infiltration rates mainly for larger macropores, and should be taken into account in hydrological applications.

Fischer, Christine; Britta, Merkel; Nico, Eisenhauer; Christiane, Roscher; Sabine, Attinger; Stefan, Scheu; Anke, Hildebrandt

2013-04-01

368

Fog reduces transpiration in tree species of the Canarian relict heath-laurel cloud forest (Garajonay National Park, Spain).  

PubMed

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

Ritter, Axel; Regalado, Carlos M; Aschan, Guido

2009-04-01

369

Rapid plant species loss at high rates and at low frequency of N addition in temperate steppe.  

PubMed

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

Zhang, Yunhai; Lü, Xiaotao; Isbell, Forest; Stevens, Carly; Han, Xu; He, Nianpeng; Zhang, Guangming; Yu, Qiang; Huang, Jianhui; Han, Xingguo

2014-11-01

370

How to help woody plants to overcome drought stress?-a control study of four tree species in Northwest China.  

NASA Astrophysics Data System (ADS)

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.

Liu, Xiaozhen; Zhang, Shuoxin

2010-05-01

371

Cyclic variations in nitrogen uptake rate of soybean plants: effects of external nitrate concentration  

NASA Technical Reports Server (NTRS)

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-.

Tolley-Henry, L.; Raper, C. D. Jr; Granato, T. C.; Raper CD, J. r. (Principal Investigator)

1988-01-01

372

Influence of soil moisture stress on transpiration from a grain sorghum canopy  

E-print Network

transpiration R vs '4 available water 54 12 Relationship between Q and integrated soil water potential )PI 56 13 Actual transpiration vs potential ET for two different treatments (Lysimeter 7, SVJSDF = 203. 5, Lysimeter 10, SWSDF = 3. 1) 57 Figure 14 15... 16 17 18 19 Actual transpiration vs PET*FL for two d i f f eren t trea tme nts Measured vs calculated relative trans- piration R for treatment 7. Calculated R was obtained by using the error function model Measured vs calculated relative...

Moridis, George Julius

2012-06-07

373

Integrated rate expression for the production of glucose equivalent in C 4 green plant and the effect of temperature  

Microsoft Academic Search

A temperature-dependent integrated kinetics for the overall process of photosynthesis in green plants is discussed. The C4 plants are chosen and in these plants, the rate of photosynthesis does not depend on the partial pressure of O2. Using some basic concepts like chemical equilibrium or steady state approximation, a simplified scheme is developed for\\u000a both light and dark reactions. The

Anirban Panda; Sambhu N. Datta

2007-01-01

374

Effects of row spacing, seed rate and maturity group on late planted soybean under irrigated and dryland  

E-print Network

Effects of row spacing, seed rate and maturity group on late planted soybean under irrigated Oklahoma State University SUMMARY POINTS: For Irrigated Soybean a plant population of 180,000 resulted at the dryland location. Introduction Soybean Production has increased significantly in Oklahoma the past few

Balasundaram, Balabhaskar "Baski"

375

Effect of nitrogen source, rate and time of application on soil nitrogen status and on the characteristics of the plant  

E-print Network

EFFECT OF NITROGEN SOURCE, RATE AND TIME OF APPLICATION ON SOIL NITROGEN STATUS AND ON THE CHARACTERISTICS OF THE PLANT By Mohamed K. Sadik A Thesis Submitted to the Graduate School of the Agricultural and Mechanical College of Texxas... in partial, fulfillment of the requirements for the degree of MASTER OF SCIENCE Major Subject: Soil and Plant Sciences May, 1962 EFFECT F NITROGEN SOURCE, RATE AND TIME OF APPLICATION ON SOIL NITROGEN STATUS AND ON THE CHARACTERISTICS OF THE PI ANT' A...

Sadik, Mohamed Kamal

2012-06-07

376

REGULAR ARTICLE Hyperaccumulation of nickel by Alyssum corsicum  

E-print Network

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

Sparks, Donald L.

377

Effects of Pheromone and Plant Volatile Release Rates and Ratios on Trapping Anoplophora glabripennis (Coleoptera: Cerambycidae) in China.  

PubMed

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

Meng, P S; Trotter, R T; Keena, M A; Baker, T C; Yan, S; Schwartzberg, E G; Hoover, K

2014-10-01

378

Heat pulse observations of Eucalyptus grandis transpiration in South Africa  

SciTech Connect

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.

Dye, P.J.; Olbrich, B.W. [CSIR, Sabie (South Africa). Sabie Forestry Research Center

1992-12-31

379

Dry season foliar fog uptake, reverse sapflow, and nighttime transpiration in the tropical montane cloud forests of Mexico  

NASA Astrophysics Data System (ADS)

Dry season fog is a ubiquitous feature of seasonal tropical cloud forests. Although cloud forests receive generous inputs of yearly precipitation, rainfall occurs primarily in the wet season. In the tropical montane forests of Veracruz Mexico, 80% of rainfall occurs in the wet season while fog occurs primarily in the dry season. Since dry-season fog occurs during months when precipitation is low or absent, this meteorological phenomenon may be important in alleviating dry-season water stress either directly through foliar fog uptake, or indirectly through a reduction in transpiration causing relaxation in xylem water tension. We determined the importance of fog on the water relations of a dominant tropical montane forest tree in La Cortadura Reserve in Veracruz, Mexico by using micrometeorological data and by measuring sap flow, leaf water potential and stomatal conductance throughout the canopies of three mature oak trees. Although the relative humidity is generally high in this habitat, in the dry season, humidity is lower and at times can be as low as 20% which causes high vapor pressure deficit and evaporative demand. We also screened sap flow data to detect periods of nighttime transpiration. Reverse sap flow occurred frequently in this site during periods of fog/drizzle. Foliar fog uptake occurred 30% of the time in the dry season although this reverse flow is likely insignificant in the water balance of cloud forest trees. Furthermore we detected low, but positive, flow rates flow at night. Finally, we conducted diurnal courses of leaf water potential and stomatal conductance at the end of the dry season to determine whether these trees were undergoing water stress. Results/Conclusions We found that reverse sap flow is a common phenomena in the dry season, indicating foliar fog uptake. Although the addition of fog to whole-tree water balance may be minimal, high dry season leaf water potential may indicate the importance of fog in reducing the negative physiological impact of dry periods. Nighttime transpiration is also a common phenomena in these forests and accounts for approximately 30% of total water transpired in the dry season. Climate change scenarios often predict a reduction of fog in montane habitats; our results indicate that this may have important repercussions on the physiology of montane forest trees and persistence of montane cloud forest vegetation in this region.

Gotsch, S. G.; Asbjornsen, H.; Holwerda, F.; Goldsmith, G. R.; Dawson, T. E.

2010-12-01

380

Hydraulic lift through transpiration suppression in shrubs from two arid ecosystems: patterns and control mechanisms.  

PubMed

Hydraulic lift (HL) is the passive movement of water through the roots from deep wet to dry shallow soil layers when stomata are closed. HL has been shown in different ecosystems and species, and it depends on plant physiology and soil properties. In this study we explored HL patterns in several arid land shrubs, and developed a simple model to simulate the temporal evolution and magnitude of HL during a soil drying cycle under relatively stable climatic conditions. This model was then used to evaluate the influence of soil texture on the quantity of water lifted by shrubs in different soil types. We conducted transpiration suppression experiments during spring 2005 in Chile and spring 2008 in Spain on five shrub species that performed HL, Flourensia thurifera, Senna cumingii and Pleocarphus revolutus (Chile), Retama sphaerocarpa and Artemisia barrelieri (Spain). Shrubs were covered with a black, opaque plastic fabric for a period of 48-72 h, and soil water potential was recorded at different depths under the shrubs. While the shrubs remained covered, water potential continuously increased in shallow soil layers until the cover was removed. The model output indicated that the amount of water lifted by shrubs is heavily dependent on soil texture, as shrubs growing in loamy soils redistributed up to 3.6 times more water than shrubs growing on sandy soils. This could be an important consideration for species growing in soils with different textures, as their ability to perform HL would be context dependent. PMID:20364271

Prieto, Iván; Martínez-Tillería, Karina; Martínez-Manchego, Luis; Montecinos, Sonia; Pugnaire, Francisco I; Squeo, Francisco A

2010-08-01

381

Effect of elevated atmospheric carbon dioxide and open-top chambers on transpiration in a tallgrass prairie  

SciTech Connect

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.

Bremer, D.J.; Ham, J.M.; Owensby, C.E. [Kansas State Univ., Manhattan, KS (United States)

1996-07-01

382

Evaluating the Performance and Economics of Transpired Solar Collectors for Commercial Applications: Preprint  

SciTech Connect

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.

Kozubal, E.; Deru, M.; Slayzak, S.; Norton, P.; Barker, G.; McClendon, J,

2008-07-01

383

The Sensitivity of Regional Transpiration to Land-Surface Characteristics: Significance of Feedback  

Microsoft Academic Search

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

C. M. J. Jacobs; H. A. R. de Bruin

1992-01-01

384

The sensitivity of regional transpiration to land-surface characteristics: significance of feedback  

Microsoft Academic Search

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

C. M. J. Jacobs; Bruin de H. A. R

1992-01-01

385

Penman–Monteith reference evapotranspiration adapted to estimate irrigated tree transpiration  

Microsoft Academic Search

The Penman–Monteith equation as parameterized by the FAO-56 bulletin to compute grass reference evapotranspiration (E0, Lgroundm?2d?1) was used to predict transpiration of irrigated orchard apple trees, olives, grapevines, kiwifruit and an isolated walnut tree. Sap flow (S, Lplant?1d?1) measured by the compensation heat-pulse technique was taken as the tree transpiration on a daily time scale, and it proved to be

Antonio Roberto Pereira; Steve Green; Nilson Augusto Villa Nova

2006-01-01

386

Estimates of deep drainage rates at the U.S. Department of Energy Pantex Plant, Amarillo, Texas  

SciTech Connect

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.

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

387

What determines the complex kinetics of stomatal conductance under blueless PAR in Festuca arundinacea? Subsequent effects on leaf transpiration.  

PubMed

Light quality and, in particular, its content of blue light is involved in plant functioning and morphogenesis. Blue light variation frequently occurs within a stand as shaded zones are characterized by a simultaneous decrease of PAR and blue light levels which both affect plant functioning, for example, gas exchange. However, little is known about the effects of low blue light itself on gas exchange. The aims of the present study were (i) to characterize stomatal behaviour in Festuca arundinacea leaves through leaf gas exchange measurements in response to a sudden reduction in blue light, and (ii) to test the putative role of Ci on blue light gas exchange responses. An infrared gas analyser (IRGA) was used with light transmission filters to study stomatal conductance (gs), transpiration (Tr), assimilation (A), and intercellular concentration of CO(2) (Ci) responses to blueless PAR (1.80 mumol m(-2) s(-1)). The results were compared with those obtained under a neutral filter supplying a similar photosynthetic efficiency to the blueless PAR filter. It was shown that the reduction of blue light triggered a drastic and instantaneous decrease of gs by 43.2% and of Tr by 40.0%, but a gradual stomatal reopening began 20 min after the start of the low blue light treatment, thus leading to new steady-states. This new stomatal equilibrium was supposed to be related to Ci. The results were confirmed in more developed plants although they exhibited delayed and less marked responses. It is concluded that stomatal responses to blue light could play a key role in photomorphogenetic mechanisms through their effect on transpiration. PMID:20444905

Barillot, Romain; Frak, Ela; Combes, Didier; Durand, Jean-Louis; Escobar-Gutiérrez, Abraham J

2010-06-01

388

What determines the complex kinetics of stomatal conductance under blueless PAR in Festuca arundinacea? Subsequent effects on leaf transpiration  

PubMed Central

Light quality and, in particular, its content of blue light is involved in plant functioning and morphogenesis. Blue light variation frequently occurs within a stand as shaded zones are characterized by a simultaneous decrease of PAR and blue light levels which both affect plant functioning, for example, gas exchange. However, little is known about the effects of low blue light itself on gas exchange. The aims of the present study were (i) to characterize stomatal behaviour in Festuca arundinacea leaves through leaf gas exchange measurements in response to a sudden reduction in blue light, and (ii) to test the putative role of Ci on blue light gas exchange responses. An infrared gas analyser (IRGA) was used with light transmission filters to study stomatal conductance (gs), transpiration (Tr), assimilation (A), and intercellular concentration of CO2 (Ci) responses to blueless PAR (1.80 ?mol m?2 s?1). The results were compared with those obtained under a neutral filter supplying a similar photosynthetic efficiency to the blueless PAR filter. It was shown that the reduction of blue light triggered a drastic and instantaneous decrease of gs by 43.2% and of Tr by 40.0%, but a gradual stomatal reopening began 20 min after the start of the low blue light treatment, thus leading to new steady-states. This new stomatal equilibrium was supposed to be related to Ci. The results were confirmed in more developed plants although they exhibited delayed and less marked responses. It is concluded that stomatal responses to blue light could play a key role in photomorphogenetic mechanisms through their effect on transpiration. PMID:20444905

Barillot, Romain; Frak, Ela; Combes, Didier; Durand, Jean-Louis; Escobar-Gutierrez, Abraham J.

2010-01-01

389

Emission rate modeling and risk assessment at an automobile plant from painting operations  

SciTech Connect

Pollution from automobile plants from painting operations has been addressed in the Clean Act Amendments (1990). The estimation of pollutant emissions from automobile painting operation were done mostly by approximate procedures than by actual calculations. The purpose of this study was to develop a methodology for calculating the emissions of the pollutants from painting operation in an automobile plant. Five scenarios involving an automobile painting operation, located in Columbus (Ohio), were studied for pollutant emission and concomitant risk associated with that. In the study of risk, a sensitivity analysis was done using Crystal Ball{reg{underscore}sign} on the parameters involved in risk. This software uses the Monte Carlo principle. The most sensitive factor in the risk analysis was the ground level concentration of the pollutants. All scenarios studied met the safety goal (a risk value of 1 x 10{sup {minus}6}) with different confidence levels. The highest level of confidence in meeting the safety goal was displayed by Scenario 1 (Alpha Industries). The results from the scenarios suggest that risk is associated with the quantity of released toxic pollutants. The sensitivity analysis of the various parameter shows that average spray rate of paint is the most important parameter in the estimation of pollutants from the painting operations. The entire study is a complete module that can be used by the environmental pollution control agencies for estimation of pollution levels and estimation of associated risk. The study can be further extended to other operations in an automobile industry or to different industries.

Kumar, A.; Shrivastava, A.; Kulkarni, A.

1999-07-01

390

Differential Atmospheric Controls on Transpiration of Boreal Trees: A Potential Factor in Pre-mature Tree Mortality in Green-Tree Retention Strategies  

NASA Astrophysics Data System (ADS)

Green-tree retention, a harvesting strategy that involves the preservation of isolated and interconnected patches of live trees within the boundaries of harvested areas, is assumed to emulate natural disturbance, while preserving forest canopy continuity for wildlife habitat, maintaining forest biodiversity, and many other landscape level objectives. Unfortunately, many of the retention trees die within a few years after harvesting, thus much of the desired function of these trees is lost. This research focuses on understanding the relationship between changes in micro-climate following harvesting and transpiration, potentially leading to drought-induced mortality of aspen, balsam poplar, white spruce, and white birch. Continuous measurements of whole-tree water use (sap flow) and micro-climate were taken before and after harvesting of two adjacent boreal mixedwood stands in west-central Alberta in the summer of 2003. Differences in micro-climate including radiation, air temperature, relative humidity and wind penetration into the canopy produced large differences in atmospheric moisture demand (PET) between partially harvested (green-tree retention) and undisturbed forest canopies. The variability in atmospheric conditions created large differences in sap flow velocity and transpiration rates among these four boreal species. Differential transpiration rates among species will be discussed in context of atmospheric controls on water use and drought tolerance of boreal trees with differing autecology and/or hydraulic architecture.

Bladon, K. D.; Silins, U.; Lieffers, V. J.

2004-05-01

391

Fluctuations in the surface activity and dose rate in localities in the near zone of the chernobyl nuclear power plant  

Microsoft Academic Search

In 1986, massive efforts, incIuding systematic measurements of the exposed 3' dose rate and the extraction of soil samples in particular, were done at localities in the 100-km contamination zone of the Chernobyl nuclear power plant accident [1]. Comparison of the measured exposed dose rate with calculations of the radionuclide composition of the soil have been published. However, the dose

R. V. Artyunyan; L. A. Bol'shov; V. E. Gorshkov; E. P. Lifshits; V. I. Tarasov; E. V. Tkalya; V. V. Chironov

1993-01-01

392

The sensitivity of regional transpiration to land-surface characteristics: Significance of feedback  

SciTech Connect

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.

Jacobs, C.M.J.; De Bruin, H.A.R. (Agricultural Univ., Wageningen (Netherlands))

1992-07-01

393

A quantitative application of the thermoelectric method for measuring water uptake by cotton plants  

E-print Network

. The relationship between Qm az d Qc for the MT series . . . . 41 10. The relationship between Qm az:d Qc for the HT series 43 11. Influence of soil znoisture tension upon transpiz ation rates of cotton plant 48 12. The effect of soil moisture tension... irzdicate;hat scii moisture, as expected, has a pz'onounced effect upon transpiration rate and consequently on growth of vegetative azd reproduc ive organs of the plazts. Soil moisture again was fou. . d not to be equally available in the range frozn...

Naghshineh-Pour, Bahman

2012-06-07

394

Cyclic variations in nitrogen uptake rate in soybean plants: uptake during reproductive growth  

NASA Technical Reports Server (NTRS)

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.

Vessey, J. K.; Raper, C. D. Jr; Henry, L. T.; Raper CD, J. r. (Principal Investigator)

1990-01-01

395

The influence of plant spacing and rates of nitrogen on the morphology of two rice varieties  

E-print Network

of the rice plant. However, the morphological characteristics in which the farmer is most, interested are influenced by the genetic make-up of the plant, climatic conditions in which the plant is grown, soil fertility, and the density of plant population... influencing plant growth and development. The rice "grower" usually grows rice in geographical areas that are well adapted to rica production. In this use of certain areas the farmer is trying to control the climatic factors influencing his crop. He may...

Stansel, James Wilbert

2012-06-07

396

Transpiration-purged optical probe: a novel sensor for high temperature harsh environments  

SciTech Connect

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.

VanOsdol, J.G.; Woodruff, S.D.; Straub, D.L.

2007-10-05

397

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)

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.

Schilling, O. S.; Doherty, J.; Kinzelbach, W.; Wang, H.; Yang, P. N.; Brunner, P.

2014-11-01

398

Effect of drought on leaf gas exchange, carbon isotope discrimination, transpiration efficiency and productivity in field grown durum wheat genotypes .  

E-print Network

??Under drought prone conditions, wheat productivity is strongly related to photosynthetic activity and transpiration efficiency. In the present study, photosynthesis related traits were assessed at… (more)

Monneveux, Philippe

2006-01-01

399

Numerical simulation of gas-phonon coupling in thermal transpiration flows.  

PubMed

Thermal transpiration is a rarefied gas flow driven by a wall temperature gradient and is a promising mechanism for gas pumping without moving parts, known as the Knudsen pump. Obtaining temperature measurements along capillary walls in a Knudsen pump is difficult due to extremely small length scales. Meanwhile, simplified analytical models are not applicable under the practical operating conditions of a thermal transpiration device, where the gas flow is in the transitional rarefied regime. Here, we present a coupled gas-phonon heat transfer and flow model to study a closed thermal transpiration system. Discretized Boltzmann equations are solved for molecular transport in the gas phase and phonon transport in the solid. The wall temperature distribution is the direct result of the interfacial coupling based on mass conservation and energy balance at gas-solid interfaces and is not specified a priori unlike in the previous modeling efforts. Capillary length scales of the order of phonon mean free path result in a smaller temperature gradient along the transpiration channel as compared to that predicted by the continuum solid-phase heat transfer. The effects of governing parameters such as thermal gradients, capillary geometry, gas and phonon Knudsen numbers and, gas-surface interaction parameters on the efficiency of thermal transpiration are investigated in light of the coupled model. PMID:19905439

Guo, Xiaohui; Singh, Dhruv; Murthy, Jayathi; Alexeenko, Alina A

2009-10-01

400

Plants and their relationship to soil moisture and tracer movement  

SciTech Connect

To obtain a better understanding of the mechanisms for possible movement of radionuclides or other toxic materials from waste burial sites in arid to semiarid regions, changes in soil moisture and tracer (Co, Cs, Sr, and tritium) movement were compared for bare vs vegetated soils. During the course of two growing seasons, comparing vegetated with bare soils, plant transpiration processes significantly reduced the soil moisture. In the vegetated soils, most of the Co, Cs, and Sr remained in the region of original emplacement. In bare soils, Co and Cs underwent minimum movement, but the peak concentration of Sr moved downward. For all tracers in the vegetated soils, there was some evidence that slight amounts of tracer had been absorbed in the plant roots and brought to the surface through plant translocation processes. In all cases, there was no significant upward movement of Co, Cs, and Sr. For tritium, the vegetated soils, compared with the bare soils, retained the maximum inventories near the original emplacement location. Although all soils showed some tritium loss, it was greatest in the vegetated soils. A literature review associated with the experiment indicated that plant species alone does not determine rooting depth, rate of transpiration, nutrient uptake, and other plant-associated processes. Environmental conditions are just as important as plant species and must be included in modeling plant-related effects. More data are needed on the effects of tracer concentration, soil water composition, variations in precipitation with time and intensity, evaporation rates, variations in soil composition, soil microorganisms, other invertebrates and vertebrates that inhabit soils, litter decay, and colloid movement on contaminant movement under conditions of unsaturated flow.

Perkins, B.; DePoorter, G.L.

1985-11-01

401

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)

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.

Govardhan, K.; Kaladhar, K.; Nagaraju, G.; Balaswamy, B.

2014-12-01

402

Selecting Plants and Nitrogen Rates to Vegetate Crude-Oil–Contaminated Soil  

Microsoft Academic Search

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.

W. D. Kirkpatrick; P. M. White Jr; D. C. Wolf; G. J. Thoma; C. M. Reynolds

2006-01-01

403

Relationships between nitrogen rate, plant nitrogen concentration, yield and residual soil nitrate?nitrogen in silage corn  

Microsoft Academic Search

Nitrogen (N) fertilizer is a key factor of yield increase but also an environmental pollution hazard. The sustainable agriculture system should have an acceptable level of productivity and profitability and an adequate environmental protection. The objectives of this study were to determine the relationships between N rate, DM yield, plant N concentration (NC) and residual soil nitrate?nitrogen in order to

D. Isfan; J. Zizka; A. DAvignon; M. Deschênes

1995-01-01

404

Study of deposition control using transpiration. Technical progress report, September 1984  

SciTech Connect

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 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 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 particles sizes under conditions simulating gas turbine conditions.

Louis, J.F.; Kozlu, H.

1984-01-01

405

Physiological responses of Vicia faba plants to sulfur dioxide  

SciTech Connect

Exposure of broad bean (Vicia faba L.) plants to 270 +/- 32 and 670 +/- 45 micrograms m 3SO{sub 2} for 1.5 hr daily between 40 and 85 days of their ages resulted in an increase in their transpiration rate, water saturation deficit, phenol content, and peroxidase activity and a decrease in protein content. With the increase in number of exposures of plants to SO{sub 2}, chlorotic and brown, necrotic visible injury signs were also developed in leaves. It was further noted that the magnitude of undesirable biochemical changes, which possibly helped in the formation of new pigment characteristic of necrotic tissue of SO{sub 2}-exposed plants, was not totally dependent on the pollutant concentration.

Nandi, P.K.; Agrawal, M.; Agrawal, S.B.; Rao, D.N. (Banaras Hindu Univ., Varanasi (India))

1990-02-01

406

Plants  

NSDL National Science Digital Library

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Berneski, Miss

2011-12-10

407

Dose-rate effects on the radiation-induced oxidation of electric cable used in nuclear power plants  

NASA Astrophysics Data System (ADS)

Dose-rate effects were measured for typical ethylene propylene rubber (EPR) and crosslinked polyethylene (XLPE) electric cable used in nuclear power plants. The radiation source was the 60Co Irradiation Facility at the University of Virginia. Dose rates were varied from 5 Gy/h to 2500 Gy/h. It was found that there is little or no dose-rate effect at low doses for four of the five EPR cable products tested from 2500 Gy/h down to dose rates of 5 Gy/h but perhaps a small dose-rate effect at high doses for dose rates above 340 Gy/h. A small dose-rate exists for the fifth EPR above 340 Gy/h at all doses. A dose-rate effect exists above 40 Gy/h for two of the three XLPE cable products tested, but there is no dose-rate for these XLPE's between 40 Gy/h and 5 Gy/h. These results indicate that the dose-rate effects observed are due to oxygen diffusion effects during heterogeneous aging and suggest that there is no dose-rate effect for either EPR or XLPE during homogeneous aging.

Reynolds, A. B.; Bell, R. M.; Bryson, N. M. N.; Doyle, T. E.; Hall, M. B.; Mason, L. R.; Quintric, L.; Terwilliger, P. L.

1995-01-01

408

Comparisons among species composition, leaf area, and water relations in three shrub-steppe plant communities  

SciTech Connect

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.

Link, S.O.; Kirkham, R.R.; Thiede, M.E.; Downs, J.L.; Gee, G.W.

1987-03-01

409

Quantification of excess water loss in plant canopies warmed with infrared heating.  

PubMed

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

De Boeck, Hans J; Kimball, Bruce A; Miglietta, Franco; Nijs, Ivan

2012-09-01

410

Expansion and photosynthetic rate of leaves of soybean plants during onset of and recovery from nitrogen stress  

NASA Technical Reports Server (NTRS)

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.

Tolley-Henry, L.; Raper, C. D. Jr; Raper CD, J. r. (Principal Investigator)

1986-01-01

411

Responses of the Tomato (Lycopersicon esculentum Mill.) Plant to Exposure to Different Salt Forms and Rates  

Microsoft Academic Search

We aimed to investigate the effects of NaCl and Na2SO4 on seed and pollen germination of tomato (Lycopersicon esculentum Mill.) in vitro. In addition, the effects of NaCl, Na2SO4, and CaCl2 on yield and quality, plant growth, some physiological parameters, and the distribution of mineral composition in greenhouse grown tomato plants were investigated. Seed germination was affected by high salinity

A. Levent TUNA; Betül BÜRÜN; Hakan ALTUNLU; Filiz ALTAN; Cengiz KAYA

2008-01-01

412

A simplified analytical solution for thermal response of a one-dimensional, steady state transpiration cooling system in radiative and convective environment  

NASA Technical Reports Server (NTRS)

A simplified analytical method for calculation of thermal response within a transpiration-cooled porous heat shield material in an intense radiative-convective heating environment is presented. The essential assumptions of the radiative and convective transfer processes in the heat shield matrix are the two-temperature approximation and the specified radiative-convective heatings of the front surface. Sample calculations for porous silica with CO2 injection are presented for some typical parameters of mass injection rate, porosity, and material thickness. The effect of these parameters on the cooling system is discussed.

Kubota, H.

1976-01-01

413

Multivariate genetic analysis of plant responses to water deficit and high temperature revealed contrasting adaptive strategies.  

PubMed

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

Vasseur, François; Bontpart, Thibaut; Dauzat, Myriam; Granier, Christine; Vile, Denis

2014-12-01

414

Monitoring Evaporation/Transpiration in a Vineyard from Two-Source Energy Balance and Radiometric Temperatures  

NASA Astrophysics Data System (ADS)

Water management and understanding of irrigation efficiency could be significantly improved if the components of evapotranspiration (ET) in row-crop systems (plants and soil interrows) could be quantified separately. This evaporation/transpiration (E/T) partition, and its daily and seasonal evolution, depends on a variety of biophysical and environmental factors. In this work we present an operational method to provide continuous E/T results avoiding soil or canopy disturbance. This technique is based on the combination of the surface-atmosphere energy exchange modeling together with an accurate remote thermal characterization of the crop elements. An experiment was carried out in a row-crop vineyard in Mallorca, Spain, from June 2012 to May 2013. A set of 6 thermal-infrared radiometers (IRTs) were mounted in a mast placed in the middle of a vineyard N-S row. Two IRTs pointed to the soil between rows and other two pointed to the plants from a frontal view, measuring both east and west sides of the row. A fifth IRT pointed upward to collect the downwelling sky radiance and the remaining IRT was mounted at 4.5-m height over the canopy measuring the composed soil-canopy temperature. Measurements of the four components of the net radiation over the canopy and soil heat fluxes, as well as air temperature, humidity, wind speed, and soil moisture, were collected and stored in 15-min averages. A two-source energy balance approach was applied to the vineyard from its appropriate thermal characterization. Total and separate soil/canopy components of net radiation, soil, sensible and latent heat fluxes were obtained every 15 minutes and averaged at hourly and daily scales. Comparison between observed and modeled values of available surface energy showed relative errors below 15%. An analysis of the partition E/T was conducted along the vineyard growing season and the different phenological stages. In this experiment, interrow soil evaporation reached as much as 1/3 of the total cumulative evapotranspiration from floration to harvest. This technique can be useful for scientists and land managers interested in improving water use efficiency, not only because it is shown as an alternative to traditional weighing lysimeters, but also because the presented method allows the continuous monitoring of the E/T partition under a variety of meteorological conditions and covering the different stages of the crop development.

Sánchez, Juan Manuel; Doña, Carolina; Cuxart, Joan; Caselles, Vicente; Niclòs, Raquel

2014-05-01

415

Extensive variation in evolutionary rate of rbcL gene sequences among seed plants.  

PubMed Central

Extensive variation in synonymous and nonsynonymous rates of substitution was observed among 50 sequences of the gene coding for the large subunit of ribulose-1,5-bisphosphate carboxylase (rbcL) representing bryophyte, conifer, dicot, and monocot taxa. Relative rate tests revealed rate differences of up to 138% for nonsynonymous substitutions and up to 85% for synonymous ones. Within angiosperms, the annual forms evolved more rapidly, on average, than perennial forms. This rate heterogeneity was more extensive at nonsynonymous sites than synonymous ones, and it resulted primarily from a recent acceleration of substitution rate in many groups of angiosperms. PMID:1502205

Bousquet, J; Strauss, S H; Doerksen, A H; Price, R A

1992-01-01

416

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

E-print Network

optimistic. Performing an error propagation on the deuterium excess value, we find s2 (d)5 s2 (d2 H)182 s2 (d)willresultinamuchhigherestimatefors(dE)than30%. Nonetheless, neglecting the propagation of errors and as an illustra- tion justP in equation (4) of ref. 1 are low, resulting in high transpiration ratios. After consulting multiple state

Cai, Long

417

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

Microsoft Academic Search

Oak savannas, once common in the Midwest, are now isolated remnants within agricultural landscapes. Savanna remnants are frequently encroached by invasive trees to become woodlands. Thinning and prescribed burning can restore savanna structure, but the ecohydrological effects of managing these remnants are poorly understood. In this study, we measured sap flow (Js) to quantify transpiration in an Iowa bur oak

H. Asbjornsen; M. D. Tomer; M. Gomez-Cardenas; L. A. Brudvig; C. M. Greenan; K. Schilling

2007-01-01

418

Transpiration, crop coefficient and water use of Olive tree (cv. Cordovil) in Southern Portugal  

Microsoft Academic Search

Orchard olive transpiration, soil water status and stomatal response in relation to water deficit were investigated to clarify mechanisms of tree water uptake and stomatal control to improve the irrigation scheduling of low-density olive trees of cv. Cordovil grown in typical Mediterranean environment of Southern Portugal. Trees were subject to three irrigation treatments. Treatment A received 100% of crop evapotranspiration

F. L. Santos

2008-01-01

419

STOMATAL CONDUCTANCE AND TRANSPIRATIONAL RESPONSES OF FIELD-GROWN COTTON TO OZONE  

EPA Science Inventory

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 (O3) concentrations. Environmental conditions during the growing season strongly aff...

420

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

E-print Network

American Institute of Aeronautics and Astronautics 1 Variable Transpiration Cooling: A New Solution, and investigates the cooling effectiveness of variable fluid injection into the hypersonic laminar boundary layer layer neglecting the radiative thermal exchange. The code uses a coupled solution of Self-Similar Method

Texas at Arlington, University of