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1

Research in Plant Transpiration: 1962.  

National Technical Information Service (NTIS)

Experiments were conducted to measure plant transpiration in a controlled environment growth room. Radiant energy, relative humidity, and soil moisture tension had marked effects on the transpiration rate. Guard cell operation was measurably affected by m...

J. E. Pallas A. R. Bertrand D. G. Harris C. B. Elkins C. L. Parks

1965-01-01

2

Oscillations in Plant Transpiration  

Microsoft Academic Search

Plants take up water via the root system and transpire water vapour through stomatal openings. Surrounding guard and subsidiary cells control the magnitude of the openings, enabling transpiration but also CO 2 transport for photosynthesis. Rhythmic transpiration reflects rhythmic cellular control by these cells and shows a range of short-term periods (typically from a few minutes to over 100 min.

Anders Johnsson

3

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

4

Development of synchronized, autonomous, and self-regulated oscillations in transpiration rate of a whole tomato plant under water stress  

PubMed Central

Plants respond to many environmental changes by rapidly adjusting their hydraulic conductivity and transpiration rate, thereby optimizing water-use efficiency and preventing damage due to low water potential. A multiple-load-cell apparatus, time-series analysis of the measured data, and residual low-pass filtering methods were used to monitor continuously and analyse transpiration of potted tomato plants (Solanum lycopersicum cv. Ailsa Craig) grown in a temperature-controlled greenhouse during well-irrigated and drought periods. A time derivative of the filtered residual time series yielded oscillatory behaviour of the whole plant's transpiration (WPT) rate. A subsequent cross-correlation analysis between the WPT oscillatory pattern and wet-wick evaporation rates (vertical cotton fabric, 0.14 m2 partly submerged in water in a container placed on an adjacent load cell) revealed that autonomous oscillations in WPT rate develop under a continuous increase in water stress, whereas these oscillations correspond with the fluctuations in evaporation rate when water is fully available. The relative amplitude of these autonomous oscillations increased with water stress as transpiration rate decreased. These results support the recent finding that an increase in xylem tension triggers hydraulic signals that spread instantaneously via the plant vascular system and control leaf conductance. The regulatory role of synchronized oscillations in WPT rate in eliminating critical xylem tension points and preventing embolism is discussed.

Wallach, Rony; Da-Costa, Noam; Raviv, Michael; Moshelion, Menachem

2010-01-01

5

Unglazed Transpired Solar Dryers for Medicinal Plants  

Microsoft Academic Search

Three different solar drying methods were carried out on four different medicinal plants to investigate the benefits of using an unglazed transpired solar dryer (UTSD) over other traditional methods. Methods involved included drying in an unglazed transpired solar dryer (using suction air flow rate of 0.06 ms), drying in the open air under direct sun rays and a common traditional drying

Ahmed A. Hassanain

2010-01-01

6

Transpiration: Water Movement Through Plants  

NSDL National Science Digital Library

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

Tracy Sterling (New Mexico State University;)

2005-09-23

7

Phytotoxic effects of industrial and sewage waste waters on growth, chlorophyll content, transpiration rate and relative water content of potted sunflower plants  

Microsoft Academic Search

Waste water coming from two factories, namely Manquabad (fertilizer) and Bani Qura (detergents and oils) factory and Arab El-Madabegh sewage effluents were determined for their phytotoxicities and physicochemical properties. The effect of the waters on the growth, chlorophyll content, transpiration rate and leaf relative water content of sunflower plants was undertaken in pots. In addition, the phytotoxicity present in the

M. A. A. Gadallah

1996-01-01

8

Drought, Abscisic Acid and Transpiration Rate Effects on the Regulation of PIP Aquaporin Gene Expression and Abundance in Phaseolus vulgaris Plants  

PubMed Central

• Background and Aims Drought causes a decline of root hydraulic conductance, which aside from embolisms, is governed ultimately by aquaporins. Multiple factors probably regulate aquaporin expression, abundance and activity in leaf and root tissues during drought; among these are the leaf transpiration rate, leaf water status, abscisic acid (ABA) and soil water content. Here a study is made of how these factors could influence the response of aquaporin to drought. • Methods Three plasma membrane intrinsic proteins (PIPs) or aquaporins were cloned from Phaseolus vulgaris plants and their expression was analysed after 4?d of water deprivation and also 1?d after re-watering. The effects of ABA and of methotrexate (MTX), an inhibitor of stomatal opening, on gene expression and protein abundance were also analysed. Protein abundance was examined using antibodies against PIP1 and PIP2 aquaporins. At the same time, root hydraulic conductance (L), transpiration rate, leaf water status and ABA tissue concentration were measured. • Key Results None of the treatments (drought, ABA or MTX) changed the leaf water status or tissue ABA concentration. The three treatments caused a decline in the transpiration rate and raised PVPIP2;1 gene expression and PIP1 protein abundance in the leaves. In the roots, only the drought treatment raised the expression of the three PIP genes examined, while at the same time diminishing PIP2 protein abundance and L. On the other hand, ABA raised both root PIP1 protein abundance and L. • Conclusions The rise of PvPIP2;1 gene expression and PIP1 protein abundance in the leaves of P. vulgaris plants subjected to drought was correlated with a decline in the transpiration rate. At the same time, the increase in the expression of the three PIP genes examined caused by drought and the decline of PIP2 protein abundance in the root tissues were not correlated with any of the parameters measured.

AROCA, RICARDO; FERRANTE, ANTONIO; VERNIERI, PAOLO; CHRISPEELS, MAARTEN J.

2006-01-01

9

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

10

Reduction of Plant Transpiration by Cetyl Alcohol  

Microsoft Academic Search

SURFACE monomolecular films of cetyl alcohol (CH3(CH2)14CH2OH) have been shown to reduce losses by evaporation from open water surfaces1, and this application has had some successful use in Australia2. There recently appeared a report3 that the mixing of cetyl alcohol with the soil in which corn (Zea mays) plants were growing reduced their loss of water by transpiration by 40

T. F. Neales; P. E. Kriedeman

1962-01-01

11

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

12

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

13

Plant transpiration and net entropy exchange on the Earth’s surface in a Czech watershed  

Microsoft Academic Search

The influence of plant transpiration on the entropy exchange was quantified as associated with the degradation of solar energy\\u000a on the Earth’s surface covered by plants. Two surfaces were studied: (1) productive surface — plant transpiration taken as\\u000a equal to the potential one, (2) non-productive surface — plant transpiration taken as equal to zero. The entropy exchanges\\u000a associated with the

Miroslav Tesa?; ?ubomír Lichner; Jan ?ermák

2007-01-01

14

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

15

[Effects of soil water condition and microclimate on transpiration rate of rice].  

PubMed

The transpiration rate and water use efficiency (WUE) of rice were studied under high, moderate and low soil water conditions (treatments A, B and C) in the red soil area of southern China. Diurnal variation of transpiration showed that rice transpiration rate was influenced by several microclimatic factors in the field. Correlation analysis and stepping multi-regression analysis suggested that the difference of relative humidity between leaf and air, and the leaf temperature were the two main factors affecting the transpiration rate of rice. The results also showed that WUE was and yield were increased significantly in treatment B. While in treatment C, the WUE increased, but the yield of late rice decreased. The transpiration rate of early rice was decreased under moderate and low soil water treatments, but this did not happen to late rice. PMID:11813436

Chen, J; Chen, M; He, Y

2001-02-01

16

Photosynthesis, Transpiration, Leaf Temperature, and Stomatal Activity of Cotton Plants under Varying Water Potentials  

PubMed Central

Cotton plants, Gossypium hirsutum L. were grown in a growth room under incident radiation levels of 65, 35, and 17 Langleys per hour to determine the effects of vapor pressure deficits (VPD's) of 2, 9, and 17 mm Hg at high soil water potential, and the effects of decreasing soil water potential and reirrigation on transpiration, leaf temperature, stomatal activity, photosynthesis, and respiration at a VPD of 9 mm Hg. Transpiration was positively correlated with radiation level, air VPD and soil water potential. Reirrigation following stress led to slow recovery, which may be related to root damage occurring during stress. Leaf water potential decreased with, but not as fast as, soil water potential. Leaf temperature was usually positively correlated with light intensity and negatively correlated with transpiration, air VPD, and soil water. At high soil water, leaf temperatures ranged from a fraction of 1 to a few degrees above ambient, except at medium and low light and a VPD of 19 mm Hg when they were slightly below ambient, probably because of increased transpirational cooling. During low soil water leaf temperatures as high as 3.4° above ambient were recorded. Reirrigation reduced leaf temperature before appreciably increasing transpiration. The upper leaf surface tended to be warmer than the lower at the beginning of the day and when soil water was adequate; otherwise there was little difference or the lower surface was warmer. This pattern seemed to reflect transpiration cooling and leaf position effects. Although stomata were more numerous in the lower than the upper epidermis, most of the time a greater percentage of the upper were open. With sufficient soil water present, stomata opened with light and closed with darkness. Fewer stomata opened under low than high light intensity and under even moderate, as compared with high soil water. It required several days following reirrigation for stomata to regain original activity levels. Apparent photosynthesis of cotton leaves occasionally oscillated with variable amplitude and frequency. When soil water was adequate, photosynthesis was nearly proportional to light intensity, with some indication of higher rates at higher VPD's. As soil water decreased, photosynthesis first increased and then markedly decreased. Following reirrigation, photosynthesis rapidly recovered. Respiration was slowed moderately by decreasing soil water but increased before watering. Respiration slowed with increasing leaf age only on leaves that were previously under high light intensity.

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

1967-01-01

17

Effects of salt accumulation on the leaf water potential and transpiration rate of pot-grown wheat with a controlled saline groundwater table  

Microsoft Academic Search

We investigated the effects of continuous salt accumulation in the root zone of wheat. Leaf water potential and transpiration rate were measured in plants grown in an experimental pot system. Plants were grown in a controlled-environment glasshouse in sand-filled pots, in which the groundwater table was maintained at a desired depth. Saline water was recharged from the base, providing constant

Kazuhiro Nishida; Nasir M. Khan; Sho Shiozawa

2009-01-01

18

FPGA-based fused smart sensor for real-time plant-transpiration dynamic estimation.  

PubMed

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

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

2010-09-02

19

The effect of elevated CO 2 concentrations in the atmosphere on plant transpiration and water use efficiency. A study with potted carnation plants  

Microsoft Academic Search

Transpiration rates of potted spray carnation plants Cerise Royalette decreased about 0.04% per vpm CO2 between ambient atmospheric CO2 concentration and 1500 vpm CO2 at several light flux densities and leaf temperatures. Measurements of daily water losses of potted spray carnation plants placed under high solar radiation conditions in two minigreenhouses with 300 and 5000 vpm CO2 demonstrated that elevated

H. Z. Enoch; R. G. Hurd

1979-01-01

20

Sensitivity and Variability of Maximum Trunk Shrinkage, Midday Stem Water Potential, and Transpiration Rate in Response to Withholding Irrigation from Field-grown Apple Trees  

Microsoft Academic Search

The sensitivity of water stress indicators to changing moisture availability, and their variability, determine the number of measurements that should be taken in order to represent properly plant water status in a certain orchard. In the present study we examined the sensitivity and variability of maximum daily trunk shrinkage, midday stem water potential, and daily transpiration rate in their responses

S. Cohen

21

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

22

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

23

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

24

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

NASA Astrophysics Data System (ADS)

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

Federer, C. Anthony

1982-04-01

25

Estimation of banana ( Musa sp.) plant transpiration using a standard 20 cm pan in a greenhouse  

Microsoft Academic Search

An experiment was carried out in a naturally ventilated greenhouse to study the relationship between banana (Musa sp.) plant transpiration (Tr) measured with load cells, reference crop evapotranspiration (ETo) calculated with five widely used models (i.e. the Priestley-Taylor, FAO radiation, Hargreaves, FAO Penman and FAO Penman-Monteith\\u000a models) and pan evaporation (Epan) measured with a standard Chinese 20 cm pan. Microclimatic conditions

Hai-Jun Liu; Shabtai Cohen; Josef Tanny; Jorge Hugo Lemcoff; GuanHua Huang

2008-01-01

26

Application of Wireless Sensor Networks to measure the plant and soil characteristics within the transpiration process  

NASA Astrophysics Data System (ADS)

Transpiration plays an important role in the land-atmospheric interactions. The performance of a land-surface model in the land-atmospheric system can be enhanced by the improvement of the representation of the internal phenomenon of the plant and the soil behavior during transpiration. This study aims to measure plant¡¦s internal phenomenon and soil behavior during the transpiration process by using a wireless sensor network. Sensor motes, as a part of the new wireless sensor network technology, have the ability to connect the observation instruments to collect the data. The sensor mote was designed with low power consumption and it is able to deliver the observation data to the base station through the wireless network. The programmable sensor mote also has the ability to work under different time intervals or trigger after certain events. This study tries to connect the measure instruments to the wireless sensor motes to measure the phenomenon inside the tree and within the soil. Initial results of this investigation will be presented and discussed.

Kuo, C.; Liang, X.; Davis, T.; Yu, P.

2007-12-01

27

Ecophysiological relevance of cuticular transpiration of deciduous and evergreen plants in relation to stomatal closure and leaf water potential.  

PubMed

The water permeability of the leaves of three deciduous plants (Acer campestre, Fagus sylvatica, Quercus petraea) and two evergreen plants (Hedera helix, Ilex aquifolium) was analysed in order to assess its role as a mechanism of drought resistance. Cuticular permeances were determined by measurement of the water loss through adaxial, astomatous leaf surfaces. Minimum conductances after complete stomatal closure were obtained by leaf drying curves. The comparison of the water permeabilities determined with these two experimental systems revealed good agreement in the case of Acer, Fagus, Quercus, and Ilex. For Hedera the minimum conductance was 3-fold higher than the cuticular permeance indicating a significant contribution of residual stomatal transpiration. The leaf water potential was measured as a function of water content and analysed by pressure-volume curves. The influence of water potential as a component of the driving force for transpirational water loss was assessed in order to identify modifications of the cuticular barrier by the leaf water content. The ecophysiological meaning of the water relations parameters describing transpiration under drought conditions (cuticular transpiration, minimum transpiration, residual stomatal transpiration, effect of leaf water content on transpiration) and the water relations parameters derived from pressure-volume curves (osmotic potential at full saturation, turgor loss point, bulk modulus of elasticity) are discussed with regard to adaptations for drought resistance. PMID:12815029

Burghardt, Markus; Riederer, Markus

2003-06-18

28

Xylem transport and shoot accumulation of lumichrome, a newly recognized rhizobial signal, alters root respiration, stomatal conductance, leaf transpiration and photosynthetic rates in legumes and cereals.  

PubMed

* Root respiration, stomatal conductance, leaf transpiration and photosynthetic rates were measured in phytotron and field-grown plants following the application of 5 or 10 nM lumichrome, 10 nM ABA (abscisic acid) and 10 ml of 0.2 OD600 infective rhizobial cells. * Providing soybean and cowpea roots with their respective homologous rhizobia and/or purified lumichrome increased the concentration of this molecule in xylem sap and leaf extracts. Relative to control, rhizobial inoculation and lumichrome application significantly increased root respiration in maize, decreased it in lupin, but had no effect on the other test species. * Applying either lumichrome (10 nM), infective rhizobial cells or ABA to roots of plants for 44 h in growth chambers altered leaf stomatal conductance and transpiration in cowpea, lupin, soybean, Bambara groundnut and maize, but not in pea or sorghum. Where stomatal conductance was increased by lumichrome application or rhizobial inoculation, it resulted in increased leaf transpiration relative to control plants. Treating roots of field plants of cowpea with this metabolite up to 63 d after planting showed decreased stomatal conductance, which affected CO2 intake and reduction by Rubisco. * The effect of rhizobial inoculation closely mirrored that of lumichrome application to roots, indicating that rhizobial effects on these physiological activities were most likely due to lumichrome released into the rhizosphere. PMID:15720696

Matiru, V N; Dakora, F D

2005-03-01

29

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

NASA Astrophysics Data System (ADS)

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

Roderick, Michael

2013-04-01

30

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

31

CONTROLS ON TRANSPIRATION IN A DESERT RIPARIAN COTTONWOOD FOREST 1609  

Technology Transfer Automated Retrieval System (TEKTRAN)

Plant-available water in desert riparian forests is very heterogeneously distributed in space and time. Up-scaling tree transpiration in these systems is necessary for determining riparian water balance and the amount of water required to sustain forest structure and function. Rates of transpiration...

32

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

NASA Astrophysics Data System (ADS)

We measured forest water use in a native mixed-species eucalypt forest for 222 days.Transpiration was strongly driven by atmospheric VPD.We validated a soil–plant–atmosphere model (SPA).Leaf area index was the most important input for estimating forest water use.SPA contributes to water resource management tools in south-east Australia.

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

2013-06-01

33

Part I. Controlling the Soil Moisture Environment of Transpiring Plants. Part II. Prediction of Leaf Temperature Under Natural Atmospheric Conditions.  

National Technical Information Service (NTIS)

A technique for controlling the soil moisture potential in the root zone of transpiring plants was developed. The method uses the principles of unsaturated flow through a porous media to develop the desired moisture potential. In the case of non-steady st...

C. T. Haan B. J. Barfield R. Edling

1970-01-01

34

Transpiration and Assimilation of Early Devonian Land Plants with Axially Symmetric Telomes—Simulations on the Tissue Level  

Microsoft Academic Search

Early terrestrial ancestors of the land flora are characterized by a simple, axially symmetric habit and evolved in an atmosphere with much higher CO2concentrations than today. In order to gain information about the ecophysiological interrelationships of these plants, a model dealing with their gaseous exchange, which is basic to transpiration and photosynthesis, is introduced. The model is based on gas

W. KONRAD; A. R OTH-NEBELSICK; H KERP; H. HASS

2000-01-01

35

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

2013-06-03

36

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...

37

Effect of temperature and humidity on the transpiration rate of the whole mushrooms  

Microsoft Academic Search

Water loss or transpiration is an important physiological process that affects the main quality characteristics of fresh mushrooms, such as saleable weight, appearance and texture. A loss in weight of only 5% may cause fresh produce to lose freshness and appear wilted and it is an important parameter to be considered while designing packaging. A setup was developed to monitor

P. V. Mahajan; F. A. R. Oliveira; I. Macedo

2008-01-01

38

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

39

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

PubMed Central

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

Tullus, Arvo; Kupper, Priit; Sellin, Arne; Parts, Leopold; Sober, Jaak; Tullus, Tea; Lohmus, Krista; Sober, Anu; Tullus, Hardi

2012-01-01

40

Transpiration- and Growth-Induced Water Potentials in Maize 1  

PubMed Central

Recent evidence from leaves and stems indicates that gradients in water potential (?w) necessary for water movement through growing tissues are larger than previously assumed. Because growth is sensitive to tissue ?w and the behavior of these gradients has not been investigated in transpiring plants, we 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 ?w measured in the mature regions of the plant responded primarily to transpiration, while the ?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 ?w along the transpiration stream while the growth-induced potentials formed a gradient of decreasing ?w from the transpiration stream to the expanding cells in the growing tissue. The growth-induced gradient in ?w within the leaf remained fairly constant as the xylem ?w decreased during the day and was associated with a decreased osmotic potential (?s) of the growing region (osmotic adjustment). The growth-induced gradient in ?w was not caused by excision of the tissue because intact maize stems exhibited a similar ?w. These observations support the concept that large gradients in ?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 ?w for cell enlargement may be an important role for osmotic adjustment.

Westgate, Mark E.; Boyer, John S.

1984-01-01

41

Individual variation of sap-flow rate in large pine and spruce trees and stand transpiration: a pilot study at the central NOPEX site  

Microsoft Academic Search

Transpiration in a mixed old stand of sub-boreal forest in the Norunda region (central Sweden) was estimated on the basis of direct measurement of sap flow rate in 24 large Scots pine and Norway spruce trees in July and August 1993. Sap flow rate was measured using the trunk tissue heat balance method based on internal (electric) heating and sensing

J. ?ermák; E. Cienciala; J. Ku?era; A. Lindroth; E. Bedná?ová

1995-01-01

42

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

PubMed

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

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

2012-08-06

43

Continuous measurement of macronutrient ions in the transpiration stream of intact plants using the meadow spittlebug coupled with ion chromatography.  

PubMed

A method is described for continuous, nondestructive analysis of xylem-borne mineral nutrients in intact transpiring plants. The method uses the xylem-feeding insect the meadow spittlebug (Philaenus spumarius L. [Homoptera: Cercopidae]). This insect will feed from a wide range of plant species and organs. Insect excreta can be collected at all times of the day and night, and its mineral ion content can be analyzed rapidly, and without purification, by ion chromatography. The excreta will have a mineral content virtually identical to that of xylem sap. Cages suitable for containing the insects and collecting excreta from any desired location on plants in both laboratory and greenhouse are described. Even in the greenhouse, evaporation had only a minor effect on the sample ion content. Example results are presented which illustrate dynamics, over several days, in the xylem concentrations of sodium (Na(+)), potassium (K(+)), NH(4)(+), magnesium (Mg(2+)), calcium (Ca(2+)), chloride (Cl(-)), NO(3)(-), PO(4)(3-), and SO(4)(2-). These data were collected from young plants growing in pots of compost in the laboratory and from fully mature pepper (Capsicum annuum L. cv Bellboy) plants growing in hydroponics (rockwool) in the greenhouse. This method should facilitate studies of macronutrient uptake and transport in a range of plants and environments. PMID:12428008

Malone, Michael; Herron, Michelle; Morales, M-Angeles

2002-11-01

44

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

45

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

Technology Transfer Automated Retrieval System (TEKTRAN)

Heat-balance sap flow gauges were configured to produce a more thermally uniform stem cross section under high flow rates. On mature grapevines (Vitis labruscana) either undisturbed in the field or transplanted to large containers (ca. 1m3 volume), with stem diameters up to 46 mm and leaf area per v...

46

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

47

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

48

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

2010-07-12

49

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.

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

2010-01-01

50

Estimation of whole-plant transpiration of bananas using sap flow measurements.  

PubMed

Banana, one of the largest rhizomatous herbs in the world, is the fourth most important global food crop. It has a high water requirement, but the whole-plant water use in the field has not been determined satisfactorily. In this study, whole-plant water use in potted and field-grown banana plants (Musa 'Cavendish' cv. Williams) was successfully determined using a xylem sap flow method. This was achieved using Granier sensor probes implanted into the central cylinder of the banana corm. The whole-plant water use in field-grown bananas was 9-10 l plant(-1) d(-1). The values of daily total sap flow in potted plants correlated closely with gravimetric measurements (r(2)=0.92) and with changes in soil water status (r(2)=0.77). In well-watered, mature, field-grown plants, hourly sap flow also closely correlated with changes in solar radiation, vapour pressure deficit and evapotranspiration. The study indicates that sap flow measurement is a sensitive and accurate method for determining whole-plant water use in bananas under potted as well as field conditions. PMID:12147727

Lu, Ping; Woo, Kam-Chau; Liu, Zhu-Tian

2002-08-01

51

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

PubMed

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

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

2005-11-01

52

The diurnal course of plant water potential, stomatal conductance and transpiration in a papyrus ( Cyperus papyrus L.) canopy  

Microsoft Academic Search

The diurnal course of water potential, stomatal conductance and transpiration was measured on mature umbels (the major evaporating surface) of papyrus (Cyperus papyrus L.) growing in a fringing swamp on Lake Naivasha, Kenya.

M. B. Jones; F. M. Muthuri

1984-01-01

53

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

54

Plant-Water-Use Efficiency with Growth Regulators and Transpiration Suppressants.  

National Technical Information Service (NTIS)

Water stress in plants may be minimized by the use of cultural practices that stimulate early growth, reduce water loss, restrict vegetative growth, control fruit set, and/or, hasten maturity, thus reducing the need for irrigation. Tomato and pepper seeds...

D. J. Fieldhouse

1972-01-01

55

Impact of photosynthesis and transpiration on nitrogen removal in constructed wetlands  

Microsoft Academic Search

To determine the impact of photosynthesis and transpiration on nitrogen removal in wetlands, an artificial wetland planted\\u000a with reeds was constructed to treat highly concentrated domestic wastewater. Under different meteorological and hydraulic\\u000a conditions, the daily changes of photosynthesis and transpiration of reeds, as well as nitrogen removal efficiency were measured.\\u000a It was found that net photosynthesis rate per unit leaf

Weiguo Luo; Shihe Wang; Juan Huang; Lu Yan; Jun Huang

2007-01-01

56

Interspecies comparison of transpiration in Cambodia for the prediction of water use under the tropical monsoon climate  

NASA Astrophysics Data System (ADS)

Recently exotic fast-growing trees are planted in Southeast Asia, since economical profits of fast-growing tree plantations are expected. However, fast-growing species are also thought to consume more water than native species. There is concern these exotic species may influence water resources because of their large water consumption, especially during the dry season. In Cambodia there is a clear rainy season and extremely dry season with hardly any rainfall. Whether fast-growing trees adapt to such dry season and their effect on water resources is unconcern. To evaluate the impact of planting exotic trees, it is critical to know how much water these trees transpired and how they control water use under drought condition. To more thoroughly understand these processes, water flow was monitored in the stem of 4 species continuously using sap flux measurement to estimate transpiration of individual trees. For this experiment, we selected 6 trees of each species; two native species (Dipterocarpus obtusifolius and Shorea roxburghii) and 2 exotic species (Acacia auriculiformis and Eucalyptus camaldulensis). Meteorological observations were also conducted. All species had similar transpiration rates under the same environmental condition in the rainy season. Although there was a relationship between tree size and transpiration, difference among the tree species was not clear. That is to say, the difference of transpiration between small size trees and large trees was larger than interspecies variation in that period. From long-term observations, we found that transpiration of native and exotic species in the dry season show different responses to environmental conditions. While transpiration of A. auriculiformis slightly decreased during the dry season, the transpiration rate of S. roxburghii, a native species, remained high despite diminished groundwater at the end of the dry season. This result implies S. roxburghii develops deeper roots to access groundwater for supporting higher transpiration rate compared to A. auriculiformis.

Tateishi, Makiko; Miyazawa, Yoshiyuki; Tomo'Omi, Kumagai; Ma, Vuthy; Sokh, Heng; Mizoue, Nobuya

2010-05-01

57

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

2012-02-15

58

Effects of overcast and foggy conditions on transpiration rates of Pinus patula trees along a chronosequence within the cloud belt of the Sierra Madre Oriental, central Veracruz, Mexico  

NASA Astrophysics Data System (ADS)

Pinus patula is a native tree species of the montane cloud belt of central Veracruz, Mexico, and one of the most popular species for regional reforestation efforts, both within and outside its natural range of occurrence. Projected regional climate change is likely to cause a rise in the average cloud condensation level by several hundred meters, thereby reducing fog occurrence, whilst overcast conditions are likely to remain similar. To improve our understanding of how water use of P. patula plantations is affected by changes in climatic conditions, we analyzed the response of transpiration rates to fine-scale variations in microclimate, particularly fog immersion and the occurrence of high clouds. We conducted measurements of micrometeorological parameters and transpiration (Et, using the heat ratio sap flow technique) of 15 pine trees representing a range of ages (10-34 years) and sizes (7-60 cm of dbh) during one and a half years (Nov 2008 - May 2010), covering two dry seasons and one wet season. Foggy days were defined using daytime “M-of-N” constructs (at least 4 hours with visibility <1000 m within 6 consecutive hourly observations), and days with overcast conditions as having a median daytime visibility > 1000 m and a maximum incoming solar radiation (Sin) < 700 W m-2. Precipitation and leaf wetness data were used to distinguish between (partly) wet and dry canopy conditions. Daily transpiration rates were normalized for climatic conditions using the FAO reference evaporation ETo to allow determination of the proportional contributions to Et suppression by reductions in Sin and VPD relative to leaf wetness. We found that both foggy and overcast conditions without rainfall produced similar % of Et reduction compared to sunny conditions (60-70%). The strongest Et suppression effects occurred when foggy or overcast conditions were associated with rainfall. However, there was just a slight and non significant difference between the average Et/ETo ratio for foggy days with rainfall (i.e. partially wetted canopy) and fog-only days, suggesting that the suppression of Et was mainly caused by reductions in VPD and Sin. Further, reverse daytime sap flow rates (possibly due to water uptake by tree crowns) occurred almost exclusively during periods with fog and rainfall, i.e. zero VPD and wet canopy conditions. We also found significant differences between the response of young and mature pines, as the Et/ETo ratios for both foggy and overcast conditions declined exponentially with tree age/size. The Et suppression effect of high and low clouds (without rainfall) likely does not have a major impact on annual water use by P. patula, because these conditions occur only about 5% of the time during the dry season (when ETo is greatest) and usually in the (late) afternoons when diurnal transpiration is already declining.

Alvarado-Barrientos, M. S.; Holwerda, F.; Asbjornsen, H.; Sauer, T.; Dawson, T. E.; Bruijnzeel, L. A.

2010-12-01

59

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.

60

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

61

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.

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

2012-01-01

62

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

63

Interannual Variation in Stand Transpiration is Dependent Upon Tree Species  

NASA Astrophysics Data System (ADS)

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

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

2003-12-01

64

Transpiration and yield relationships of grain sorghum grown in a field environment  

Technology Transfer Automated Retrieval System (TEKTRAN)

The ability of plants to convert transpiration into dry matter has been studied since the early 20th century. Research has compared differences among species using transpiration efficiency (TE), the ratio of biomass yield (Yb) to transpiration (T); and m and k, which are the slopes of the linear Yb...

65

Changes in Transpiration induced by Ethyl Alcohol  

Microsoft Academic Search

ETHYL alcohol was used as an auxiliary solvent in the preparation of auxin solutions for a series of transpiration experiments with plants in water culture when the roots were supplied with different auxins at varying concentrations. This method appears to be fairly common for auxin studies1,2. After weighing, the auxin is dissolved in a small quantity of ethyl alcohol, and

S. Allerup

1962-01-01

66

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

67

Stomatal Closure in Flooded Tomato Plants Involves Abscisic Acid and a Chemically Unidentified Anti-Transpirant in Xylem Sap.  

PubMed Central

We address the question of how soil flooding closes stomata of tomato (Lycopersicon esculentum Mill. cv Ailsa Craig) plants within a few hours in the absence of leaf water deficits. Three hypotheses to explain this were tested, namely that (a) flooding increases abscisic acid (ABA) export in xylem sap from roots, (b) flooding increases ABA synthesis and export from older to younger leaves, and (c) flooding promotes accumulation of ABA within foliage because of reduced export. Hypothesis a was rejected because delivery of ABA from flooded roots in xylem sap decreased. Hypothesis b was rejected because older leaves neither supplied younger leaves with ABA nor influenced their stomata. Limited support was obtained for hypothesis c. Heat girdling of petioles inhibited phloem export and mimicked flooding by decreasing export of [14C]sucrose, increasing bulk ABA, and closing stomata without leaf water deficits. However, in flooded plants bulk leaf ABA did not increase until after stomata began to close. Later, ABA declined, even though stomata remained closed. Commelina communis L. epidermal strip bioassays showed that xylem sap from roots of flooded tomato plants contained an unknown factor that promoted stomatal closure, but it was not ABA. This may be a root-sourced positive message that closes stomata in flooded tomato plants.

Else, M. A.; Tiekstra, A. E.; Croker, S. J.; Davies, W. J.; Jackson, M. B.

1996-01-01

68

Transpiration of apple trees in a humid climate using heat pulse sap flow gauges calibrated with whole-canopy gas exchange chambers  

Microsoft Academic Search

For scientific study and practical irrigation management, the estimate of plant transpiration and water use rates is needed. Several methods are available to measure water use by plants, and among them, sap flow estimation techniques are currently popular, although the interpretation of data may be complex due to several assumptions. In this study, we present a combined approach to measure

D. Dragoni; A. N. Lakso; R. M. Piccioni

2005-01-01

69

THE DIFFERENTIAL RESPONSE OF TRANSPIRATION AND BARE-SOIL EVAPORATION TO PRECIPITATION IN A CHIHUAHUAN DESERT SHRUBLAND 1642  

Technology Transfer Automated Retrieval System (TEKTRAN)

In general the coupled response of bare soil evaporation and plant transpiration following precipitation pulses is not well understood in most ecosystems. To better understand how precipitation is partitioned into evaporation and transpiration following natural precipitation events we measured whol...

70

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

71

National Wetland Plant List Indicator Rating Definitions.  

National Technical Information Service (NTIS)

For over two decades, the National List of Plant Species that Occur in Wetlands has served as the standard reference for plant species wetland indicator status ratings in the United States. In 2012 the list, now called the National Wetland Plant List, was...

M. L. Butterwick N. C. Melvin R. W. Lichvar W. N. Kirchner

2012-01-01

72

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

73

Relationships between stem diameter, sapwood area, leaf area and transpiration in a young mountain ash forest.  

PubMed

We examined relationships between stem diameter, sapwood area, leaf area and transpiration in a 15-year-old mountain ash (Eucalyptus regnans F. Muell.) forest containing silver wattle (Acacia dealbata Link.) as a suppressed overstory species and mountain hickory (Acacia frigescens J.H. Willis) as an understory species. Stem diameter explained 93% of the variation in leaf area, 96% of the variation in sapwood area and 88% of the variation in mean daily spring transpiration in 19 mountain ash trees. In seven silver wattle trees, stem diameter explained 87% of the variation in sapwood area but was a poor predictor of the other variables. When transpiration measurements from individual trees were scaled up to a plot basis, using stem diameter values for 164 mountain ash trees and 124 silver wattle trees, mean daily spring transpiration rates of the two species were 2.3 and 0.6 mm day(-1), respectively. The leaf area index of the plot was estimated directly by destructive sampling, and indirectly with an LAI-2000 plant canopy analyzer and by hemispherical canopy photography. All three methods gave similar results. PMID:14965913

Vertessy, R A; Benyon, R G; O'Sullivan, S K; Gribben, P R

1995-09-01

74

Enhanced transpiration in response to wind effects at the edge of a blue gum (Eucalyptus globulus) plantation.  

PubMed

In Australia, tree planting has been widely promoted to alleviate dryland salinity and one proposed planting configuration is that of strategically placed interception belts. We conducted an experiment to determine the effect of tree position in a belt on transpiration rate. We also assessed how much the effect of tree position can be explained by advection and environmental conditions. Daily transpiration rates were determined by the heat pulse velocity technique for four edge and 12 inner trees in a 7-year-old Tasmanian blue gum (Eucalyptus globulus) plantation in South Australia. Various climatic variables were logged automatically at one edge of the plantation. The relationship between daily sap flow and sapwood area was strongly linear for the edge trees (r2 = 0.97), but only moderately correlated for the inner trees (r2 = 0.46), suggesting an edge effect. For all trees, sap flow normalized to sapwood area (Qs) increased with potential evaporation (PE) initially and then became independent as PE increased further. There was a fairly close correlation between transpiration of the edge and inner trees, implying that water availability was partially responsible for the difference between inner and edge trees. However, the ratio of edge tree to inner tree transpiration differed from unity, indicating differences in canopy conductance, which were estimated by an inverse form of the Penman-Monteith equation. When canopy conductances were less than a critical value, there was a strong linear relationship between Qs of the edge and inner trees. When canopy conductances of the edge trees were greater than the critical value, the slope of the linear relationship was steeper, indicating greater transpiration of the edge trees compared with the inner trees. This was interpreted as evidence for enhancement of transpiration of the edge trees by advection of wind energy. PMID:11282580

Taylor, P J; Nuberg, I K; Hatton, T J

2001-04-01

75

Energy balance and transpiration from tussock grassland in New Zealand  

NASA Astrophysics Data System (ADS)

The energy balance was measured for the dry canopy of narrow-leaved snow tussock ( Chionochloa rigida), and measurements of transpiration were obtained from a large weighing lysimeter. Typical maximum summer transpiration rates of 0.21 0.43 mmhr-1 (140 290 W m-2) were recorded. The latent heat flux accounted for less than 40% of net radiation. The estimated value of the bulk stomatal resistance ( r ST) for 29 days was 158 s m-1, and the decoupling parameter (?) was 0.17. Transpiration rates were not driven directly by net radiation, but were closely linked to the size of the regional saturation deficit imposed at the level of the canopy by efficient overhead mixing, and were constrained by a large bulk stomatal resistance. A linear relationship between r ST and the saturation deficit is proposed as a realistic method for estimating transpiration for water yield studies of tussock catchments.

Campbell, D. I.

1989-01-01

76

Bayesian analysis for uncertainty estimation of a canopy transpiration model  

NASA Astrophysics Data System (ADS)

A Bayesian approach was used to fit a conceptual transpiration model to half-hourly transpiration rates for a sugar maple (Acer saccharum) stand collected over a 5-month period and probabilistically estimate its parameter and prediction uncertainties. The model used the Penman-Monteith equation with the Jarvis model for canopy conductance. This deterministic model was extended by adding a normally distributed error term. This extension enabled using Markov chain Monte Carlo simulations to sample the posterior parameter distributions. The residuals revealed approximate conformance to the assumption of normally distributed errors. However, minor systematic structures in the residuals at fine timescales suggested model changes that would potentially improve the modeling of transpiration. Results also indicated considerable uncertainties in the parameter and transpiration estimates. This simple methodology of uncertainty analysis would facilitate the deductive step during the development cycle of deterministic conceptual models by accounting for these uncertainties while drawing inferences from data.

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

2007-04-01

77

Quantifying Understory Transpiration in a Semiarid Riparian Area  

NASA Astrophysics Data System (ADS)

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

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

2005-12-01

78

Effect, Uptake and Disposition of Nitrobenzene in Several Terrestrial Plants.  

National Technical Information Service (NTIS)

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...

C. McFarlane T. Pfleeger J. Fletcher

1990-01-01

79

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

PubMed Central

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 (?l) in Semillon was negatively correlated to vapour pressure deficit (VPD) both predawn and during the day. Furthermore, ?l fell to significantly lower values than in any of the nine other varieties examined. Night-time values of stomatal conductance (gn) and transpiration (En) in Semillon were up to four times higher than in other varieties; plants enclosed in plastic bags overnight to reduce En resulted in better plant–soil equilibration so that predawn ?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 ?l values in Semillon during warm, dry nights. The other contributing factor is daytime stomatal conductance (gday), which in Semillon leaves was higher than in other varieties, although the decline in gday with increasing VPD was greater in Semillon than in Shiraz or Grenache. The high values of gday were associated with high rates of transpiration (Eday) 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.

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

2009-01-01

80

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

USGS Publications Warehouse

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

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

2008-01-01

81

Effects of potassium deficiency on water relations and photosynthesis of the tomato plant  

Microsoft Academic Search

Potassium deficient (?K) and potassium sufficient (+K) plants were exposed to four days of water stress. Well watered ?K and\\u000a +K plants had comparable rates of transpiration. But +K plants had a larger leaf area and depleted the soil moisture to a\\u000a greater extent on day 1 of stress. For days 2 and 3 their transpiration rate, leaf water potential

M. H. Behboudian; D. R. Anderson

1990-01-01

82

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

Microsoft Academic Search

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

Sanjay Kumar; Suresh K Sinha

1994-01-01

83

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.

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

2013-01-01

84

CCMR: Modeling Transpiration with Porous Silicon Membranes  

NSDL National Science Digital Library

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

Jilo, Allen

2010-08-15

85

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

Microsoft Academic Search

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

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

1995-01-01

86

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

87

Transpiration Cooled Throat for Hydrocarbon Rocket Engines.  

National Technical Information Service (NTIS)

This program's objective 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 coo...

L. May W. M. Burkhardt

1991-01-01

88

Transpiration Cooled Throat for Hydrocarbon Rocket Engines.  

National Technical Information Service (NTIS)

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...

L. R. May W. M. Burkhardt

1991-01-01

89

Variability of Recombination Rates in Higher Plants  

Microsoft Academic Search

\\u000a Recombination and chiasma frequency, like other features of meiosis, are subject to various genetic control mechanisms. Here,\\u000a we give an overview of the genetic and environmental factors as well as the genomic structures that play a role for the variability\\u000a of recombination rates in plant genomes. Suppressed or greatly reduced recombination is observed in chromosomal regions that\\u000a contain repetitive sequences

Elisabeth Esch; Renate Horn

90

Stress-inducible expression of At DREB1A in transgenic peanut (Arachis hypogaea L.) increases transpiration efficiency under water-limiting conditions.  

PubMed

Water deficit is the major abiotic constraint affecting crop productivity in peanut (Arachis hypogaea L.). Water use efficiency under drought conditions is thought to be one of the most promising traits to improve and stabilize crop yields under intermittent water deficit. A transcription factor DREB1A from Arabidopsis thaliana, driven by the stress inducible promoter from the rd29A gene, was introduced in a drought-sensitive peanut cultivar JL 24 through Agrobacterium tumefaciens-mediated gene transfer. The stress inducible expression of DREB1A in these transgenic plants did not result in growth retardation or visible phenotypic alterations. T3 progeny of fourteen transgenic events were exposed to progressive soil drying in pot culture. The soil moisture threshold where their transpiration rate begins to decline relative to control well-watered (WW) plants and the number of days needed to deplete the soil water was used to rank the genotypes using the average linkage cluster analysis. Five diverse events were selected from the different clusters and further tested. All the selected transgenic events were able to maintain a transpiration rate equivalent to the WW control in soils dry enough to reduce transpiration rate in wild type JL 24. All transgenic events except one achieved higher transpiration efficiency (TE) under WW conditions and this appeared to be explained by a lower stomatal conductance. Under water limiting conditions, one of the selected transgenic events showed 40% higher TE than the untransformed control. PMID:17653723

Bhatnagar-Mathur, Pooja; Devi, M Jyostna; Reddy, D Srinivas; Lavanya, M; Vadez, Vincent; Serraj, R; Yamaguchi-Shinozaki, K; Sharma, Kiran K

2007-07-26

91

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

92

Transpiration response to soil moisture in pine and spruce trees in Sweden  

Microsoft Academic Search

Variation in transpiration and conductance between individual trees of Scots pine and Norway spruce was investigated in a mixed 50-year-old stand in central Sweden. Daily transpiration rates were measured by the tissue heat balance method on five trees of each species during a dry, warm growing season. Daytime averages of sapflow, climatic variables and soil water content were used to

Fredrik Lagergren; Anders Lindroth

2002-01-01

93

Seasonal transpiration pattern of Phragmites australis in a wetland of semi-arid Spain  

NASA Astrophysics Data System (ADS)

Transpiration rates were measured in a flooded population of Phragmites australis ssp. altissima in a wetland located in El Hondo Natural Park (southeastern Spain) during the growing season of 2000. The heat balance method for measuring sap flow was used to calculate the rate of water transpiration on a whole-stem basis. Four series of measurements were carried out in selected weeks in May, June, August and October. Structure, biomass and leaf area index of the reed population were simultaneously quantified in order to scale transpiration on a plot-area basis.Overall, transpiration flux was high during the sampling period and showed a typical diurnal pattern with a maximum at about midday. Mean transpiration was highest at the end of June coinciding with the peak of reed growth and with the maximum leaf area both at individual and plot scales. Rates decreased abruptly in October, in parallel with the advanced foliar senescence. The variation of both midday and integrated daily transpiration is significantly related to that of the air temperature on clear days. Cloudy and rainy days exert a pronounced effect on water loss by decreasing transpiration. Our results highlight the potential use of the sap-flow method to measure transpiration in reed ecosystems and the relevance of this flux for the water balance in wetlands in semi-arid environments. Thus, it is suggested that water management in these areas could be favoured by acquiring high-quality experimental data.

Moro, María José; Domingo, Francisco; López, Germán

2004-02-01

94

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

95

Transpiration-induced changes in the photosynthetic capacity of leaves  

Microsoft Academic Search

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

Thomas D. Sharkey

1984-01-01

96

Identification and characterization of QTL underlying whole-plant physiology in Arabidopsis thaliana: delta13C, stomatal conductance and transpiration efficiency  

Microsoft Academic Search

Water limitation is one of the most important factors lim- iting crop productivity world-wide and has likely been an important selective regime influencing the evolution of plant physiology. Understanding the genetic and physiolog- ical basis of drought adaptation is therefore important for improving crops as well as for understanding the evolution of wild species. Here, results are presented from quantita-

THOMAS E. JUENGER; JOHN K. MCKAY; NEIL HAUSMANN; JOOST J. B. KEURENTJES; SAUNAK SEN; KIRK A. STOWE; TODD E. DAWSON; ELLEN L. SIMMS; JAMES H. RICHARDS

2005-01-01

97

Differential antioxidative responses in transgenic peanut bear no relationship to their superior transpiration efficiency under drought stress.  

PubMed

To counter the effects of environmental stresses, the plants must undergo detoxification that is crucial to avoid the accumulation of damaging free oxygen radicals (ROI). Here, we detail the oxidative damage, the antioxidant composition, and the osmoprotection achieved in transgenic plants of peanut overexpressing the AtDREB1A transgene, driven by a stress-inducible promoter (Atrd29A) when exposed to progressive water stress conditions. This study explored the biochemical mechanisms where (i) the antioxidants such as superoxide dismutase (SOD), ascorbate peroxidase (APOX), and glutathione reductase (GR) accumulated in the transgenic plants at comparably higher levels than their untransformed counterparts under dry soil conditions, (ii) a significant increase in the proline levels in the transgenic plants was observed in dry soils, and (iii) a dramatic increase in the lipid peroxidation in the untransformed controls in drier soils. Most of the biochemical parameters related to the antioxidative machinery in the tested peanut transgenics were triggered by the overexpression of AtDREB1A that appeared to differ from the untransformed controls. The antioxidants showed a negative correlation with the fraction of transpirable soil water (FTSW) thresholds, where the normalized transpiration rate (NTR) started decreasing in the tested plants. However, no significant relationship was observed between any of these biochemical indicators and the higher transpiration efficiency (TE) values found in the transgenic events. Our results show that changes in the antioxidative machinery in these transgenic peanut plants (overexpressing the AtDREB1A transcription factor) under water-limiting conditions played no causative role in improved TE. PMID:19201508

Bhatnagar-Mathur, Pooja; Devi, M Jyostna; Vadez, Vincent; Sharma, Kiran K

2009-02-07

98

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

99

Effect of temperature on cuticular transpiration of isolated cuticular membranes and leaf discs.  

PubMed

Cuticular transpiration was measured in the temperature range between 10 degrees C and 55 degrees C using tritiated water and five species (Vinca major L., Prunus laurocerasus L., Forsythia intermedia L., Citrus aurantium L., and Hedera helix L.). Cuticular water permeabilities measured with isolated cuticular membranes were not different from cuticular water permeabilities measured with leaf discs. Depending on the species cuticular water permeabilities increased by factors between 12 (V. major) to 264 (H. helix) when temperature was increased from 10 degrees C to 55 degrees C. Arrhenius plots (lnP versus 1/T) of all investigated species were characterized by phase transitions occurring in the temperature range of 30-39 degrees C. Activation energies for water permeability across plant cuticles below and above the midpoint of phase transition were calculated from Arrhenius plots. Depending on the species they varied between 26 (F. intermedia) to 61 kJ mol(-1) (H. helix) below the phase transition and from 67 (V. major) to 122 kJ mol(-1) (F. intermedia) above the phase transition. Since the occurrence of phase transitions always lead to significantly increased rates of cuticular transpiration it is argued that temperatures higher than 35 degrees C caused structural defects to the transport-limiting barrier of the plant cuticles of all species investigated. PMID:11520878

Schreiber, L

2001-09-01

100

Reduced atmospheric pressure in Radish: Alteration of NCER and transpiration at decreased oxygen partial pressures  

NASA Astrophysics Data System (ADS)

Fundamental to the future of space exploration is the development of advanced life support systems capable of maintaining crews for significant periods without re-supply from Earth. Significant research is focused on the development of bioregenerative life support systems to be used in conjunction with the current physico-chemical methods. These bioregenerative life support systems harness natural ecosystem processes and employ plant photosynthesis and transpiration to produce food, oxygen and regenerate water while consuming carbon dioxide. The forthcoming exploration of the Moon and Mars has prompted interest into the effects of hypobaria on plant development. Reduced atmospheric pressures will lessen the pressure gradient between the structure and the local environment thereby decreasing gas leakage and possibly the structural mass of the plant growth facility. In order to establish the optimal specifications for reduced pressure plant growth structures it is essential to determine the atmospheric pressure limits required for conventional plant development and growth. Due to its physiological importance, oxygen will compose a significant portion of these minimal environments. The objective of this study was to test the hypothesis that reduced atmospheric pressure and decreased oxygen partial pressures had no effect on radish productivity. Radishes (Raphanus sativa L. cv. Cherry Bomb II) were grown from seed in the University of Guelph's Hypobaric Plant Growth Chambers for a period of 21 days. Treatments included total pressures of 10, 33, 66 and 96 kPa and oxygen partial pressures of 2, 7, 14 and 20 kPa. Experiments demonstrated that reduced partial pressures of oxygen had a greater effect on radish growth than hypobaria. Results showed a reduction in net carbon exchange rate and transpiration with decreasing oxygen partial pressures leading to diminished productivity. Keywords: hypobaric, radish, oxygen partial pressure, variable pressure chamber, bioregenerative life support

Wehkamp, Cara Ann; Stasiak, Michael; Wheeler, Raymond; Dixon, Mike

101

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

ERIC Educational Resources Information Center

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

Gibson, Paul R.

102

Involvement of phytochrome in regulation of transpiration: red-\\/far red-induced responses in the chlorophyll-deficient mutant of pea  

Microsoft Academic Search

Transpiration rhythmicity and intensity were investigated in the chlorophyll-deficient mutant XL18 of Pisum sativum L. and in the phytochrome-deficient mutant aurea of Lycopersicon esculentum Mill. A custom-built psychrometer was used. In the XL18 mutant an acute transpiration response to monochromatic irradiation was observed such that red (R) light increased and far-red (FR) decreased transpiration rate, with equal rates of change.

Svetlana V. SokolskayaA; Natalia V. SveshnikovaA; Galina V. KochetovaA; Alexei E. SolovchenkoC; Sergei A. GostimskiB; Ouliana B. Bashtanova

2003-01-01

103

Transpiring wall supercritical water oxidation reactor salt deposition studies  

SciTech Connect

Sandia National Laboratories has teamed with Foster Wheeler Development Corp. and GenCorp, Aerojet to develop and evaluate a new supercritical water oxidation reactor design using a transpiring wall liner. In the design, pure water is injected through small pores in the liner wall to form a protective boundary layer that inhibits salt deposition and corrosion, effects that interfere with system performance. The concept was tested at Sandia on a laboratory-scale transpiring wall reactor that is a 1/4 scale model of a prototype plant being designed for the Army to destroy colored smoke and dye at Pine Bluff Arsenal in Arkansas. During the tests, a single-phase pressurized solution of sodium sulfate (Na{sub 2}SO{sub 4}) was heated to supercritical conditions, causing the salt to precipitate out as a fine solid. On-line diagnostics and post-test observation allowed us to characterize reactor performance at different flow and temperature conditions. Tests with and without the protective boundary layer demonstrated that wall transpiration provides significant protection against salt deposition. Confirmation tests were run with one of the dyes that will be processed in the Pine Bluff facility. The experimental techniques, results, and conclusions are discussed.

Haroldsen, B.L.; Mills, B.E.; Ariizumi, D.Y.; Brown, B.G. [and others

1996-09-01

104

Transpirational demand affects aquaporin expression in poplar roots.  

PubMed

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

Laur, Joan; Hacke, Uwe G

2013-04-18

105

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

106

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

EPA Science Inventory

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

107

Effects of plant gross morphology on predator consumption rates.  

PubMed

We find that spatial structure, and in particular, differences in gross plant morphology, can alter the consumption rates of generalist insect predators. We compared Asian lady beetle, Harmonia axyridis Pallas, and green lacewing larvae, Chrysoperla carnea Stephens, consumption rates of pea aphids, Acyrthosiphon pisum Harris, in homogeneous environments (petri dishes) and heterogeneous environments (whole plants). Spatial complexity is often described as reducing predator success, and we did find that predators consumed significantly more aphids on leaf tissue in petri dishes than on whole plants with the same surface area. However, subtle differences in plant morphology may have more unexpected effects. A comparison of consumption rates on four different isogenic pea morphs (Pisum sativum L.) controlled for surface area indicated that both lady beetles and lacewings were more successful on morphologies that were highly branched. We speculate that predators move more easily over highly branched plants because there are more edges to grasp. PMID:22732608

Reynolds, Paula G; Cuddington, Kim

2012-06-01

108

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

Microsoft Academic Search

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

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

2003-01-01

109

Contributions of foliage distribution and leaf functions to light interception, transpiration and photosynthetic capacities in two apple cultivars at branch and tree scales.  

PubMed

Both the spatial distribution of leaves and leaf functions affect the light interception, transpiration and photosynthetic capacities of trees, but their relative contributions have rarely been investigated. We assessed these contributions at the branch and tree scales in two apple cultivars (Malus x domestica Borkh. 'Fuji' and 'Braeburn') with contrasting architectures, by estimating their branch and tree capacities and comparing them with outputs from a radiation absorption, transpiration and photosynthesis (RATP) functional-structural plant model (FSPM). The structures of three 8-year-old trees of each cultivar were digitized to obtain 3-D representations of foliage geometry. Within-tree foliage distribution was compared with shoot demography, number of leaves per shoot and mean individual leaf area. We estimated branch and tree light interception from silhouette to total leaf area ratios (STAR), transpiration from sap flux measurements and net photosynthetic rates by the branch bag method. Based on a set of parameters we previously established for both cultivars, the outputs of the RATP model were tested against STAR values, sap fluxes and photosynthetic measurements. The RATP model was then used to virtually switch foliage distribution or leaf functions (stomatal and photosynthetic properties), or both, between cultivars and to evaluate the effects on branch and tree light interception, transpiration and photosynthetic capacities in each cultivar. 'Fuji' trees had a higher proportion of leaf area borne on long shoots, fewer leaves per unit shoot length and a larger individual leaf area than 'Braeburn' trees. This resulted in a lower leaf area density and, consequently, a higher STAR in 'Fuji' than in 'Braeburn' at both branch and tree scales. Transpiration and photosynthetic rates were significantly higher in 'Fuji' than in 'Braeburn'. Branch heterogeneity was greater in 'Braeburn' than in 'Fuji'. An analysis of the virtual switches of foliage distribution or leaf function showed that differences in leaf spatial distribution and functions had additive effects that accounted for the lower transpiration and photosynthetic rates of branches and trees of 'Braeburn' compared with 'Fuji'. Leaf distribution had a more important role at the branch scale than at the tree scale, but the leaf function effect exceeded the leaf distribution effect at both scales. Our study demonstrated the potential of FSPM to disentangle physiological differences between cultivars through in silico scenarios. PMID:18316299

Massonnet, C; Regnard, J L; Lauri, P E; Costes, E; Sinoquet, H

2008-05-01

110

Transpiration from forest dwelling and woodland Mygalomorphae (Araneae)  

NASA Astrophysics Data System (ADS)

Rates of water loss in dry air at room temperature (21±2°C) have been measured from seven species of forest-dwelling mygalomorph spiders. They range from 0.260% body wt h-1 in the tube-dwelling trapdoor spider Dyarcyops sp. (from the humid coastal regions of eastern Australia) to 0.030% wt h-1 in Brachypelma smithi (from drier environments in Mexico). There is a tendency for rates of transpiration to be related to the humidities of the spiders' normal environments and micro-habitats.

Cloudsley-Thompson, J. L.; Constantinou, C.

1983-03-01

111

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

PubMed

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

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

2012-09-12

112

Transpiration's Inhibition of Air Pollution Fluxes to Substomatal Cavities.  

National Technical Information Service (NTIS)

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...

W. G. N. Slinn

1987-01-01

113

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

114

Ash, Carbon Isotope Discrimination, and Silicon as Estimators of Transpiration Efficiency in Crested Wheatgrass  

Microsoft Academic Search

Breeding and selection for higher transpiration efficiency (W) has been hampered by tedious and costly methodology. Rapid and less costly methods are needed for screening W in plant improvement programmes. We report the relationship of ash, silicon (Si) concentration, and Si uptake to W in crested wheatgrass (Agropyron desertorum (Fischer ex Link) Schultes), an important C3 range grass in western

H. F. Mayland; D. A. Johnson; K. H. Asay; A USDA-ARS; B USDA-ARS

115

Sewage Disposal by Evaporation-Transpiration.  

National Technical Information Service (NTIS)

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...

E. R. Bennett K. D. Linstedt

1978-01-01

116

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...

117

Relating xylem cavitation to transpiration in cotton  

Technology Transfer Automated Retrieval System (TEKTRAN)

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

118

Light-induced transpiration alters cell water relations in figleaf gourd (Cucurbita ficifolia) seedlings exposed to low root temperatures.  

PubMed

Water relation parameters including elastic modulus (epsilon), half-times of water exchange (T(w)(1/2)), hydraulic conductivity and turgor pressure (P) were measured in individual root cortical and cotyledon midrib cells in intact figleaf gourd (Cucurbita ficifolia) seedlings, using a cell pressure probe. Transpiration rates (E) of cotyledons were also measured using a steady-state porometer. The seedlings were exposed to low ambient (approximately 10 micromol m(-2) s(-1)) or high supplemental irradiance (approximately 300 micromol m(-2) s(-1) PPF density) at low (8 degrees C) or warm (22 degrees C) root temperatures. When exposed to low irradiance, all the water relation parameters of cortical cells remained similar at both root temperatures. The exposure of cotyledons to supplemental light at warm root temperatures, however, resulted in a two- to three-fold increase in T(w)(1/2) values accompanied with the reduced hydraulic conductivity in both root cortical (Lp) and cotyledon midrib cells (Lp(c)). Low root temperature (LRT) further reduced Lp(c) and E, whether it was measured under low or high irradiance levels. The reductions of Lp as the result of respective light and LRT treatments were prevented by the application of 1 microM ABA. Midrib cells required higher concentrations of ABA (2 microM) in order to prevent the reduction in Lp(c). When the exposure of cotyledons to light was accompanied by LRT, however, ABA proved ineffective in reversing the inhibition of Lp. LRT combined with high irradiance triggered a drastic 10-fold reduction in water permeability of cortical and midrib cells and increased epsilon and T(w)(1/2) values. Measurement of E indicated that the increased water demand by the transpiring plants was fulfilled by an increase in the apoplastic pathway as principal water flow route. The importance of water transport regulation by transpiration affecting the hydraulic conductivity of the roots is discussed. PMID:18346079

Lee, Seong Hee; Zwiazek, Janusz J; Chung, Gap Chae

2008-03-11

119

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

NASA Astrophysics Data System (ADS)

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

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

2010-12-01

120

Uptake rate of nitrogen dioxide by potato plants  

SciTech Connect

Greenhouse-grown potato plants were exposed to nitrogen dioxide in an exposure chamber to determine the rate of NO/sub 2/ uptake at concentrations from 228 to 817 ..mu..g/m/sup 3/ (0.12-0.43 ppm). Results show that a consistent increase in uptake rate accompanied an increase in NO/sub 2/ exposure concentrations. Exposure in the range of concentration had no significant effect on leaf diffusive resistance.

Sinn, J.P.; Pell, E.J.; Kabel, R.L.

1984-06-01

121

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

122

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

Microsoft Academic Search

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

Justin Ramsey; Douglas W. Schemske

1998-01-01

123

Mercaptan removal rate exceeds 99% at Canadian gas plant  

Microsoft Academic Search

Installation of a Selexol solvent unit at Pembina Resources Ltd.'s Diamond Valley gas plant has been effective in polishing mercaptans and other sulfur-bearing compounds from a variable gas stream. The actual removal rate exceeds 99%, and an absolute treated gas target of < 100 ppm total sulfur is maintained. In addition, hydrocarbon pick up is restricted sufficiently so that slugs

Judd

1993-01-01

124

Make Your Own Transpiring Tree  

ERIC Educational Resources Information Center

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

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

2003-01-01

125

Metabolism of Transpired Ethanol by Eastern Cottonwood (Populus deltoides Bartr.).  

PubMed

Ethanol has previously been shown to be present in the xylem sap of flooded and nonflooded trees. Because of the constitutive presence of alcohol dehydrogenase in the mature leaves of woody plants, we hypothesized that the leaves and shoots of trees had the ability to metabolize ethanol supplied by the transpiration stream. 1-[14C]Ethanol was supplied to excised leaves and shoots of eastern cottonwood (Populus deltoides Bartr.) in short- and long-term experiments. More than 99% of the radiolabel was incorporated into plant tissue in short-term experiments, with more than 95% of the label remaining in plant tissue after 24 h. In all experiments, less than 5% of the label was transpired as ethanol and less than 1% was emitted as CO2. In excised leaf experiments, less than 0.5% of the radiolabel escaped from the leaf. Fifty percent of the label was incorporated into the petioles of excised leaves; 56% was incorporated into the stems of excised shoots. Very little label reached the leaf mesophyll cells of excised shoots, as revealed by autoradiography. Radiolabel appeared primarily in the water- and chloroform-soluble fractions in short-term experiments, whereas in long-term experiments, label was also incorporated into protein. These results demonstrate that the leaves and stems of trees appear to have substantial ability to scavenge ethanol from the transpiration stream, allowing efficient recovery of ethanol produced elsewhere by hypoxic tissues. When labeled ethanol was supplied to excised petioles in a 5-min pulse, 41% of the label was incorporated into organic acids. Some label was also incorporated into amino acids, protein, and the chloroform-soluble fraction, with very little appearing in neutral sugars, starch, or the insoluble pellet. Labeled organic acids were separated by high performance liquid chromatography and were composed of acetate, isocitrate, [alpha]-ketoglutarate, and succinate. There was no apparent incorporation of label into phosphorylated compounds. We conclude that, in higher plants, ethanol is metabolized to acetaldehyde and then to acetate by alcohol and aldehyde dehydrogenases, and then into general metabolism. PMID:12231807

MacDonald, R. C.; Kimmerer, T. W.

1993-05-01

126

Metabolism of Transpired Ethanol by Eastern Cottonwood (Populus deltoides Bartr.).  

PubMed Central

Ethanol has previously been shown to be present in the xylem sap of flooded and nonflooded trees. Because of the constitutive presence of alcohol dehydrogenase in the mature leaves of woody plants, we hypothesized that the leaves and shoots of trees had the ability to metabolize ethanol supplied by the transpiration stream. 1-[14C]Ethanol was supplied to excised leaves and shoots of eastern cottonwood (Populus deltoides Bartr.) in short- and long-term experiments. More than 99% of the radiolabel was incorporated into plant tissue in short-term experiments, with more than 95% of the label remaining in plant tissue after 24 h. In all experiments, less than 5% of the label was transpired as ethanol and less than 1% was emitted as CO2. In excised leaf experiments, less than 0.5% of the radiolabel escaped from the leaf. Fifty percent of the label was incorporated into the petioles of excised leaves; 56% was incorporated into the stems of excised shoots. Very little label reached the leaf mesophyll cells of excised shoots, as revealed by autoradiography. Radiolabel appeared primarily in the water- and chloroform-soluble fractions in short-term experiments, whereas in long-term experiments, label was also incorporated into protein. These results demonstrate that the leaves and stems of trees appear to have substantial ability to scavenge ethanol from the transpiration stream, allowing efficient recovery of ethanol produced elsewhere by hypoxic tissues. When labeled ethanol was supplied to excised petioles in a 5-min pulse, 41% of the label was incorporated into organic acids. Some label was also incorporated into amino acids, protein, and the chloroform-soluble fraction, with very little appearing in neutral sugars, starch, or the insoluble pellet. Labeled organic acids were separated by high performance liquid chromatography and were composed of acetate, isocitrate, [alpha]-ketoglutarate, and succinate. There was no apparent incorporation of label into phosphorylated compounds. We conclude that, in higher plants, ethanol is metabolized to acetaldehyde and then to acetate by alcohol and aldehyde dehydrogenases, and then into general metabolism.

MacDonald, R. C.; Kimmerer, T. W.

1993-01-01

127

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

128

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...

129

Experimental Studies on Supercritical Water Oxidation of Glucose with a Transpiring Wall Reactor  

Microsoft Academic Search

An innovative system of supercritical water oxidation with a transpiring wall reactor was designed and constructed. Temperature fields inside the reactor, the contents of gas effluent, total organic carbon (TOC) removal efficiency and energy utilization efficiency of supercritical water oxidation of glucose were investigated at different feed flow rates. Higher reaction temperature, longer useful length (UL) and longer useful residence

Fengming Zhang; Shouyan Chen; Chunyan Xu; Guifang Chen; Chunyuan Ma

2011-01-01

130

Transpiration efficiency of a tropical pioneer tree (Ficus insipida) in relation to soil fertility.  

PubMed

The response of whole-plant water-use efficiency, termed transpiration efficiency (TE), to variation in soil fertility was assessed in a tropical pioneer tree, Ficus insipida Willd. Measurements of stable isotope ratios (delta(13)C, delta(18)O, delta(15)N), elemental concentrations (C, N, P), plant growth, instantaneous leaf gas exchange, and whole-plant water use were used to analyse the mechanisms controlling TE. Plants were grown individually in 19 l pots with non-limiting soil moisture. Soil fertility was altered by mixing soil with varying proportions of rice husks, and applying a slow release fertilizer. A large variation was observed in leaf photosynthetic rate, mean relative growth rate (RGR), and TE in response to experimental treatments; these traits were well correlated with variation in leaf N concentration. Variation in TE showed a strong dependence on the ratio of intercellular to ambient CO(2) mole fractions (c(i)/c(a)); both for instantaneous measurements of c(i)/c(a) (R(2)=0.69, P <0.0001, n=30), and integrated estimates based on C isotope discrimination (R(2)=0.88, P <0.0001, n=30). On the other hand, variations in the leaf-to-air humidity gradient, unproductive water loss, and respiratory C use probably played only minor roles in modulating TE in the face of variable soil fertility. The pronounced variation in TE resulted from a combination of the strong response of c(i)/c(a) to leaf N, and inherently high values of c(i)/c(a) for this tropical tree species; these two factors conspired to cause a 4-fold variation among treatments in (1-c(i)/c(a)), the term that actually modifies TE. Results suggest that variation in plant N status could have important implications for the coupling between C and water exchange in tropical forest trees. PMID:18057036

Cernusak, Lucas A; Winter, Klaus; Aranda, Jorge; Turner, Benjamin L; Marshall, John D

2007-01-01

131

Nitric acid loss rates measured in power plant plumes  

Microsoft Academic Search

Measurements of HNO3, NOx, NOy, and CO2 in the plumes from electric utility power plants located in eastern Texas are used to determine the HNO3 loss rates in the planetary boundary layer during plume transport. These 1 Hz measurements were obtained from the National Center for Atmospheric Research Electra aircraft flying on clear afternoons in a well-mixed planetary boundary layer

J. A. Neuman; D. D. Parrish; T. B. Ryerson; C. A. Brock; C. Wiedinmyer; G. J. Frost; J. S. Holloway; F. C. Fehsenfeld

2004-01-01

132

Nocturnal transpiration causing disequilibrium between soil and stem predawn water potential in mixed conifer forests of Idaho.  

PubMed

Soil water potential (Psi(s)) is often estimated by measuring leaf water potential before dawn (Psi(pd)), based on the assumption that the plant water status has come into equilibrium with that of the soil. However, it has been documented for a number of plant species that stomata do not close completely at night, allowing for nocturnal transpiration and thus preventing nocturnal soil-plant water potential equilibration. The potential for nighttime transpiration necessitates testing the assumption of nocturnal equilibration before accepting Psi(pd) as a valid estimate of Psi(s). We determined the magnitude of disequilibrium between Psi(pd) and Psi(s) in four temperate conifer species across three height classes through a replicated study in northern Idaho. Based on both stomatal conductance and sap flux measurements, we confirmed that the combination of open stomata and high nocturnal atmospheric vapor pressure deficit (D) resulted in nocturnal transpiration in all four species. Nocturnal stomatal conductance (g(s-noc)) averaged about 33% of mid-morning conductance values. We used species-specific estimates of g(s-noc) and leaf specific conductance to correct Psi(pd) values for nocturnal transpiration at the time the samples were collected. Compared with the unadjusted values, corrected values reflected a significantly higher Psi(pd) (when D > 0.12 kPa). These results demonstrate that comparisons of Psi(pd) among species, canopy height classes and sites, and across growing seasons can be influenced by differential amounts of nocturnal transpiration, leading to flawed results. Consequently, it is important to account for the presence of nocturnal transpiration, either through a properly parameterized model or by making Psi(pd) measurements when D is sufficiently low that it cannot drive nocturnal transpiration. Violating these conditions will likely result in underestimation of Psi(s). PMID:17242003

Kavanagh, Kathleen L; Pangle, Robert; Schotzko, Alisa D

2007-04-01

133

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.

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

2004-01-01

134

The Dynamics of Embolism Refilling in Abscisic Acid (ABA)-Deficient Tomato Plants  

PubMed Central

Plants are in danger of embolism formation in xylem vessels when the balance between water transport capacity and transpirational demand is compromised. To maintain this delicate balance, plants must regulate the rate of transpiration and, if necessary, restore water transport in embolized vessels. Abscisic acid (ABA) is the dominant long-distance signal responsible for plant response to stress, and it is possible that it plays a role in the embolism/refilling cycle. To test this idea, a temporal analysis of embolism and refilling dynamics, transpiration rate and starch content was performed on ABA-deficient mutant tomato plants. ABA-deficient mutants were more vulnerable to embolism formation than wild-type plants, and application of exogenous ABA had no effect on vulnerability. However, mutant plants treated with exogenous ABA had lower stomatal conductance and reduced starch content in the xylem parenchyma cells. The lower starch content could have an indirect effect on the plant’s refilling activity. The results confirm that plants with high starch content (moderately stressed mutant plants) were more likely to recover from loss of water transport capacity than plants with low starch content (mutant plants with application of exogenous ABA) or plants experiencing severe water stress. This study demonstrates that ABA most likely does not play any direct role in embolism refilling, but through the modulation of carbohydrate content, it could influence the plant’s capacity for refilling.

Secchi, Francesca; Perrone, Irene; Chitarra, Walter; Zwieniecka, Anna K.; Lovisolo, Claudio; Zwieniecki, Maciej A.

2013-01-01

135

Mercaptan removal rate exceeds 99% at Canadian gas plant  

SciTech Connect

Installation of a Selexol solvent unit at Pembina Resources Ltd.'s Diamond Valley gas plant has been effective in polishing mercaptans and other sulfur-bearing compounds from a variable gas stream. The actual removal rate exceeds 99%, and an absolute treated gas target of < 100 ppm total sulfur is maintained. In addition, hydrocarbon pick up is restricted sufficiently so that slugs of hydrocarbon are not carried through the system to destabilize incineration of the mercaptans. The paper discusses start-up problems, the gas treating process, mercaptans in the feed gas, the solvent unit, and its operation.

Judd, B. (Union Carbide Chemicals and Plastics Canada Inc., Calgary, Alberta (Canada))

1993-08-16

136

Genetic variability for leaf growth rate and duration under water deficit in sunflower: analysis of responses at cell, organ, and plant level.  

PubMed

Plants under water deficit reduce leaf growth, thereby reducing transpiration rate at the expense of reduced photosynthesis. The objective of this work was to analyse the response of leaf growth to water deficit in several sunflower genotypes in order to identify and quantitatively describe sources of genetic variability for this trait that could be used to develop crop varieties adapted to specific scenarios. The genetic variability of the response of leaf growth to water deficit was assessed among 18 sunflower (Helianthus annuus L.) inbred lines representing a broad range of genetic diversity. Plants were subjected to long-term, constant-level, water-deficit treatments, and the response to water deficit quantified by means of growth models at cell-, leaf-, and plant-scale. Significant variation among lines was found for the response of leaf expansion rate and of leaf growth duration, with an equal contribution of these responses to the variability in the reduction of leaf area. Increased leaf growth duration under water deficit is usually suggested to be caused by changes in the activity of cell-wall enzymes, but the present results suggest that the duration of epidermal cell division plays a key role in this response. Intrinsic genotypic responses of rate and duration at a cellular scale were linked to genotypic differences in whole-plant leaf area profile to water deficit. The results suggest that rate and duration responses are the result of different physiological mechanisms, and therefore capable of being combined to increase the variability in leaf area response to water deficit. PMID:18448477

Pereyra-Irujo, Gustavo A; Velázquez, Luciano; Lechner, Leandra; Aguirrezábal, Luis A N

2008-04-29

137

Photosynthesis and Water Relations in Tomato Plants Cultivated Long-Term in Media Containing (+)-Usnic Acid  

Microsoft Academic Search

The influence of (+)-usnic acid on rates of gas exchange (photosynthesis, respiration, and transpiration) in long-term cultivation of tomato plants was studied. The effect was dose-dependent. Plants grown in media containing the maximum concentration of (+)-usnic acid (30 ?M) had photosynthetic and respiration rates reduced by 41% and 80%, respectively. The effect on photosynthesis rate may be the result of a

E. Latkowska; Z. Lechowski; J. Bialczyk; J. Pilarski

2006-01-01

138

Root uptake and transpiration: From measurements and models to sustainable irrigation  

Microsoft Academic Search

Water has been labelled ‘blue gold’, and ‘blue gold’ is destined to be the critical issue of the 21st Century. Globally, irrigation is responsible for 80% of the world-wide spending of ‘blue gold’.Development of sustainable irrigation practices will require that we understand better the biophysical processes of root-water uptake in soil, and transpiration from plant canopies.Our review paper is divided

Steve R. Green; M. B. Kirkham; Brent E. Clothier

2006-01-01

139

AP Investigative labs: An inquiry-base Approach Lab 11: Transpiration  

NSDL National Science Digital Library

In this inquiry-based investigation, students calculate leaf surface area and the average number of stomata per square millimeter in a particular kind of plant. From these observations, students will be able to formulate questions about the process of transpiration and design an experiment based on previous knowledge of osmosis, diffusion, and active transport; the movement of molecules and ions across cell membranes; the physical and chemical properties of water; photosynthesis; and the exchange of matter between biological systems and the environment.

The College Board The College Board (The College Board;)

2012-10-24

140

EFFECTS OF ELEVATED CARBON DIOXIDE AND OZONE ON SOYBEAN [GLYCINE MAX (L.) MERR.] TRANSPIRATION  

Technology Transfer Automated Retrieval System (TEKTRAN)

A two-year field study was conducted to test the effects of elevated atmospheric CO2 and O3 on whole-plant transpiration in open-top chambers. Soybean (Glycine max, cv. Essex) was grown in 21 l pots and treated with charcoal-filtered air (CF) (18 nmol O3 mol-1) or CF air plus O3 (72 nmol mol-1) in ...

141

Impact of rooting depth and soil hydraulic properties on the transpiration peak of an evergreen forest in northern Thailand in the late dry season  

Microsoft Academic Search

Previous research showed that transpiration in an evergreen broad-leaved forest in northern Thailand (18°48?N, 98°54?E) peaked at the end of the dry season. However, rooting depth limitations on soil water use were not investigated. This study examined the impact of rooting depth and soil hydraulic properties on transpiration using a newly developed soil plant air continuum model. The soil texture

Katsunori Tanaka; Hideki Takizawa; Tomonori Kume; Jianqing Xu; Chatchai Tantasirin; Masakazu Suzuki

2004-01-01

142

Impact of rooting depth and soil hydraulic properties on the transpiration peak of an evergreen forest in northern Thailand in the late dry season  

Microsoft Academic Search

Previous research showed that transpiration in an evergreen broad-leaved forest in northern Thailand (18°48'N, 98°54'E) peaked at the end of the dry season. However, rooting depth limitations on soil water use were not investigated. This study examined the impact of rooting depth and soil hydraulic properties on transpiration using a newly developed soil plant air continuum model. The soil texture

Katsunori Tanaka; Hideki Takizawa; Tomonori Kume; Jianqing Xu; Chatchai Tantasirin; Masakazu Suzuki

2004-01-01

143

Towards Enhancement of the Economy of a Thermal Power Generating System through Prediction of Plant Efficiency  

Microsoft Academic Search

The plant ‘Heat Rate’ (HR) is a measure of overall efficiency of a thermal power generating system. It depends on a large number of factors, some of which are non-measurable, while data relating to others are seldom available and recorded. However, coal quality (expressed in terms of ‘effective heat value’ (EHV) as kcal\\/kg) transpires to be one of the important

Indranil Mukhopadhyay; Sudipta Chatterjee; Aditya Chatterjee

2007-01-01

144

Mycorrhizal association between the desert truffle Terfezia boudieri and Helianthemum sessiliflorum alters plant physiology and fitness to arid conditions  

Microsoft Academic Search

The host plant Helianthemum sessiliflorum was inoculated with the mycorrhizal desert truffle Terfezia boudieri Chatin, and the subsequent effects of the ectomycorrhizal relationship on host physiology were determined. Diurnal measurements\\u000a revealed that mycorrhizal (M) plants had higher rates of photosynthesis (35%), transpiration (18%), and night respiration\\u000a (49%) than non-mycorrhizal (NM) plants. Consequently, M plants exhibited higher biomass accumulation, higher shoot-to-root

Tidhar Turgeman; Jiftach Ben Asher; Nurit Roth-Bejerano; Varda Kagan-Zur; Yoram Kapulnik; Yaron Sitrit

145

Relative Contribution of Nighttime Transpiration to Daily Total Water Use by Tamarix in a Desert Riparian Woodland  

NASA Astrophysics Data System (ADS)

The phreatophytic plant, Tamarix, consumes water from the Pecos River in west Texas, forming a narrow band of dense riparian woodland in an otherwise sparsely vegetated desert environment. Narrow desert riparian zones are largely influenced by dry desert air, creating favorable conditions for nighttime transpiration. In this study, we explore whether nighttime transpiration, especially on nights with warm temperatures and low relative humidity, significantly contributes to daily total water use by Tamarix. Sixteen stems were equipped with thermal dissipation sapflow sensors and monitored during the 2004 growing season. Relative humidity near the canopy did not exceed 70% on 18 of 213 nights and remained below 90% on 77 of 213 nights observed. Sapflow continued throughout most nights, reaching a minimum just before sunrise, as stem water capacitance refilled from the previous day's losses. Antecedent conditions strongly affected the transpirational response to high nighttime evaporative demands mostly likely because of stem water capacitance dynamics during and between rain events. Significant contributions of nighttime transpiration to daily total water use may partially explain how Tamarix is capable of using large amounts of water while maintaining moderate stem conductances. Diel patterns in Pecos River stream flow correspond with evapotranspiration losses from the Tamarix riparian woodland; however, quantitative interpretation must be based on an understanding of both daily and nightly transpiration.

Moore, G. W.; Owens, K.

2005-05-01

146

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

SciTech Connect

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

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

1998-12-31

147

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

NASA Astrophysics Data System (ADS)

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

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

1981-11-01

148

Thermal transpiration of nanoscale gas flow  

NASA Astrophysics Data System (ADS)

We present a molecular dynamics (MD) methodology to investigate temperature-driven gas flow through a nanochannel connecting two reservoirs at different temperatures. The temperature gradient along the channel drives the macroscopic movement of gas molecules from the cold to the hot regions, in the phenomenon known as thermal transpiration. Temperature, density and pressure profile variations along the axial direction are measured at various rarefaction conditions, from the slip flow to the free molecular regimes. Pressure and density evolutions are monitored as a function of time in both the hot and cold reservoirs. The normalized thermo molecular pressure difference (TMPD) values are calculated and compared with kinetic theory results. Comparisons show good agreement up to the early transition regime, although beyond this our numerical experiments over-predict the theoretical results. These numerical experiments are useful because experimental data is scarce for nano devices and these molecular simulations can mimic realistic conditions.

Babac, Gulru; Dongari, Nishanth; Zhang, Yonghao; Reese, Jason M.

2012-11-01

149

Nitrogen to phosphorus ratio of plant biomass versus soil solution in a tropical pioneer tree, Ficus insipida  

PubMed Central

It is commonly assumed that the nitrogen to phosphorus (N:P) ratio of a terrestrial plant reflects the relative availability of N and P in the soil in which the plant grows. Here, this was assessed for a tropical pioneer tree, Ficus insipida. Seedlings were grown in sand and irrigated with nutrient solutions containing N:P ratios ranging from <1 to >100. The experimental design further allowed investigation of physiological responses to N and P availability. Homeostatic control over N:P ratios was stronger in leaves than in stems or roots, suggesting that N:P ratios of stems and roots are more sensitive indicators of the relative availability of N and P at a site than N:P ratios of leaves. The leaf N:P ratio at which the largest plant dry mass and highest photosynthetic rates were achieved was ?11, whereas the corresponding whole-plant N:P ratio was ?6. Plant P concentration varied as a function of transpiration rate at constant nutrient solution P concentration, possibly due to transpiration-induced variation in the mass flow of P to root surfaces. The transpiration rate varied in response to nutrient solution N concentration, but not to nutrient solution P concentration, demonstrating nutritional control over transpiration by N but not P. Water-use efficiency varied as a function of N availability, but not as a function of P availability.

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

2010-01-01

150

Antioxidative response of metal-accumulator and non-accumulator plants under cadmium stress  

Microsoft Academic Search

The present study aims to elucidate the role of antioxidative enzyme in the adaptive responses of metal-accumulators (Thlaspi caerulescens and Brassica juncea) and non-accumulator plant (Nicotiana tabacum) to Cadmium stress. When seedlings of plants were grown in hydroponic condition for a period of 4 days in the presence of\\u000a 200 or 400 ?M CdCl2, photosynthetic rate, transpiration rate and stomatal conductance in

Zi Wang; Yuxiu Zhang; Zhibo Huang; Lin Huang

2008-01-01

151

Grazing-induced losses of biodiversity affect the transpiration of an arid ecosystem  

Microsoft Academic Search

Degradation processes often lead to species loss. Such losses would impact on ecosystem functioning depending on the extinction\\u000a order and the functional and structural aspects of species. For the Patagonian arid steppe, we used a simulation model to\\u000a study the effects of species loss on the rate and variability (i.e. stability) of transpiration as a key attribute of ecosystem\\u000a functioning.

Santiago R. Verón; José M. Paruelo; Martín Oesterheld

2011-01-01

152

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

2007-12-10

153

The relationship between absorption of sulfur dioxide (SO 2 ) and inhibition of photosynthesis in several plants  

Microsoft Academic Search

Photosynthetic rate, transpiration rate and SO2 absorption rate were simultaneously measured under exposure to SO2 (0.1–1.0 ?l l\\u000a ?1) for 5 or 8 hr in six species belonging to C4 or C3 plants (Zea mays, Sorghum vulgare, Amaranthus tricolor, Oryza sativa, Avena sativa andHelianthus annuus). Distinct interspecific differences were found as to the extent of inhibition of photosynthetic rate. Calculation

Masahiko Katase; Tadahiro Ushijima; Tadayoshi Tazaki

1983-01-01

154

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

2009-08-06

155

Community Level Offset of Rain Use- and Transpiration Efficiency for a Heavily Grazed Ecosystem in Inner Mongolia Grassland  

PubMed Central

Water use efficiency (WUE) is a key indicator to assess ecosystem adaptation to water stress. Rain use efficiency (RUE) is usually used as a proxy for WUE due to lack of transpiration data. Furthermore, RUE based on aboveground primary productivity (RUEANPP) is used to evaluate whole plant water use because root production data is often missing as well. However, it is controversial as to whether RUE is a reliable parameter to elucidate transpiration efficiency (TE), and whether RUEANPP is a suitable proxy for RUE of the whole plant basis. The experiment was conducted at three differently managed sites in the Inner Mongolia steppe: a site fenced since 1979 (UG79), a winter grazing site (WG) and a heavily grazed site (HG). Site HG had consistent lowest RUEANPP and RUE based on total net primary productivity (RUENPP). RUEANPP is a relatively good proxy at sites UG79 and WG, but less reliable for site HG. Similarly, RUEANPP is good predictor of transpiration efficiency based on aboveground net primary productivity (TEANPP) at sites UG79 and WG but not for site HG. However, if total net primary productivity is considered, RUENPP is good predictor of transpiration efficiency based on total net primary productivity (TENPP) for all sites. Although our measurements indicate decreased plant transpiration and consequentially decreasing RUE under heavy grazing, productivity was relatively compensated for with a higher TE. This offset between RUE and TE was even enhanced under water limited conditions and more evident when belowground net primary productivity (BNNP) was included. These findings suggest that BNPP should be considered when studies fucus on WUE of more intensively used grasslands. The consideration of the whole plant perspective and “real” WUE would partially revise our picture of system performance and therefore might affect the discussion on the C-sequestration and resilience potential of ecosystems.

Gao, Ying Z.; Giese, Marcus; Gao, Qiang; Brueck, Holger; Sheng, Lian X.; Yang, Hai J.

2013-01-01

156

Community level offset of rain use- and transpiration efficiency for a heavily grazed ecosystem in inner mongolia grassland.  

PubMed

Water use efficiency (WUE) is a key indicator to assess ecosystem adaptation to water stress. Rain use efficiency (RUE) is usually used as a proxy for WUE due to lack of transpiration data. Furthermore, RUE based on aboveground primary productivity (RUEANPP) is used to evaluate whole plant water use because root production data is often missing as well. However, it is controversial as to whether RUE is a reliable parameter to elucidate transpiration efficiency (TE), and whether RUEANPP is a suitable proxy for RUE of the whole plant basis. The experiment was conducted at three differently managed sites in the Inner Mongolia steppe: a site fenced since 1979 (UG79), a winter grazing site (WG) and a heavily grazed site (HG). Site HG had consistent lowest RUEANPP and RUE based on total net primary productivity (RUENPP). RUEANPP is a relatively good proxy at sites UG79 and WG, but less reliable for site HG. Similarly, RUEANPP is good predictor of transpiration efficiency based on aboveground net primary productivity (TEANPP) at sites UG79 and WG but not for site HG. However, if total net primary productivity is considered, RUENPP is good predictor of transpiration efficiency based on total net primary productivity (TENPP) for all sites. Although our measurements indicate decreased plant transpiration and consequentially decreasing RUE under heavy grazing, productivity was relatively compensated for with a higher TE. This offset between RUE and TE was even enhanced under water limited conditions and more evident when belowground net primary productivity (BNNP) was included. These findings suggest that BNPP should be considered when studies fucus on WUE of more intensively used grasslands. The consideration of the whole plant perspective and "real" WUE would partially revise our picture of system performance and therefore might affect the discussion on the C-sequestration and resilience potential of ecosystems. PMID:24058632

Gao, Ying Z; Giese, Marcus; Gao, Qiang; Brueck, Holger; Sheng, Lian X; Yang, Hai J

2013-09-18

157

Experimental investigation of the degradation rate of adipic acid in wet flue gas desulphurisation plants  

Microsoft Academic Search

The aim of this work is to study the degradation rate of adipic acid in wet FGD plants using forced oxidation. The investigation is experimentally demanding because the degradation rate must be studied under realistic conditions present in pilot plants or industrial plants only. This is the first systematic investigation including both chemical and biological degradation. The influence on the

Christian N. Buchardt; Jan Erik Johnsson; Søren Kiil

2006-01-01

158

Multiple major increases and decreases in mitochondrial substitution rates in the plant family Geraniaceae  

Microsoft Academic Search

BACKGROUND: Rates of synonymous nucleotide substitutions are, in general, exceptionally low in plant mitochondrial genomes, several times lower than in chloroplast genomes, 10–20 times lower than in plant nuclear genomes, and 50–100 times lower than in many animal mitochondrial genomes. Several cases of moderate variation in mitochondrial substitution rates have been reported in plants, but these mostly involve correlated changes

Christopher L Parkinson; Jeffrey P Mower; Yin-Long Qiu; Andrew J Shirk; Keming Song; Nelson D Young; Claude W dePamphilis; Jeffrey D Palmer

2005-01-01

159

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.

160

Relationships between Phenolic Acid Concentrations, Transpiration, Water Utilization, Leaf Area Expansion, and Uptake of Phenolic Acids: Nutrient Culture Studies  

Microsoft Academic Search

Phenolic acid treatments of cucumber seedlings (Cucumis sativus cv “Early Green Cluster”) inhibited transpiration, water utilization, leaf area, and absolute and relative rates of leaf expansion. The cinnamic acids, ferulic and p-coumaric acids, were two to five times more inhibitory than the benzoic acids, p-hydroxybenzoic acid and vanillic acid. When phenolic acid concentrations were maintained at inhibitory concentrations through multiple

Udo Blum; Thomas M. Gerig

2005-01-01

161

Cytokinin Import Rate as a Signal for Photosynthetic Acclimation to Canopy Light Gradients1[W][OA  

PubMed Central

Plants growing in dense canopies are exposed to vertical light gradients and show photosynthetic acclimation at the whole-plant level, resulting in efficient photosynthetic carbon gain. We studied the role of cytokinins transported through the transpiration stream as one of probably multiple signals for photosynthetic acclimation to light gradients using both tobacco (Nicotiana tabacum) and Arabidopsis (Arabidopsis thaliana). We show that substantial variation in leaf transpiration parallels the light gradient in tobacco canopies and experimental reduction of the transpiration rate of a leaf, independent of light, is sufficient to reduce photosynthetic capacity in both species, as well as transcript levels of the small subunit of Rubisco (rbcS) gene in Arabidopsis. Mass spectrometric analysis of xylem sap collected from intact, transpiring tobacco plants revealed that shaded leaves import less cytokinin than leaves exposed to high light. In Arabidopsis, reduced transpiration rate of a leaf in the light is associated with lower cytokinin concentrations, including the bioactive trans-zeatin and trans-zeatin riboside, as well as reduced expression of the cytokinin-responsive genes ARR7 and ARR16. External application of cytokinin to shaded leaves rescued multiple shade effects, including rbcS transcript levels in both species, as did locally induced cytokinin overproduction in transgenic tobacco plants. From these data, we conclude that light gradients over the foliage of a plant result in reduced cytokinin activity in shaded leaves as a consequence of reduced import through the xylem and that cytokinin is involved in the regulation of whole-plant photosynthetic acclimation to light gradients in canopies.

Boonman, Alex; Prinsen, Els; Gilmer, Frank; Schurr, Ulrich; Peeters, Anton J.M.; Voesenek, Laurentius A.C.J.; Pons, Thijs L.

2007-01-01

162

Predicting Plant Migration Rates in a Changing World: The Role of Long?Distance Dispersal  

Microsoft Academic Search

Models of plant migration based on estimates of bio- logical parameters severely underestimate the rate of spread when compared to empirical estimates of plant migration rates. This is disturbing, since an ability to predict migration and colonization rates is needed for predicting how native species will distribute them- selves in response to habitat loss and climate change and how rapidly

Steven I. Higgins; David M. Richardson

1999-01-01

163

Coupling time to silking with plant growth rate in maize  

Microsoft Academic Search

In maize (Zea mays L.), progress towards pistillate flower maturity (silking) is highly dependent upon the environmental conditions around flowering. Under conditions that inhibit plant growth, female flower development is delayed relative to that of the male flowers resulting in an increase in the anthesis–silking interval (ASI). Although variation in ASI has been extensively documented, its relationship to plant growth

Lucas Borrás; Mark E. Westgate; Juan P. Astini; Laura Echarte

2007-01-01

164

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

165

Effects of deicing salt on the vitality and health of two spruce species, Picea abies Karst., and Picea glehnii Masters planted along roadsides in northern Japan  

Microsoft Academic Search

In northern Japan, the growth of Picea abies Karst., and Picea glehnii Masters, which have been planted along the highways, is often suppressed due to several environmental stresses. To examine the adverse effects of deicing salt, the primary source of stress, we measured needle life span, photosynthetic capacity, and water potential and transpiration rate of the two spruce species at

M Kayama; A. M Quoreshi; S Kitaoka; Y Kitahashi; Y Sakamoto; Y Maruyama; M Kitao; T Koike

2003-01-01

166

Time-dependent experimental analysis of a thermal transpiration rarefied gas flow  

NASA Astrophysics Data System (ADS)

Thermal transpiration is the macroscopic movement induced in a rarefied gas by a temperature gradient. The gas moves from the lower to the higher temperature zone. An original method is proposed here to measure the stationary mass flow rate of gas created by thermal transpiration in a micro-tube heated at its outlet. In addition, by means of a time-dependent study, parameters such as the pressure variation, the pressure variation speed, and the characteristic time of the system are analyzed. The experimental system is composed of a glass tube of circular cross section and two reservoirs positioned one at the inlet and one at the outlet of the capillary. The reservoirs are connected to two fast response time capacitance diaphragm gauges. By monitoring the pressure variation with time inside both reservoirs, it is possible to measure the macroscopic movement of the gas along the tube. Three gases, nitrogen, argon, and helium, are studied and three temperature differences ?T = 37, 53.5, and 71 K are applied to the tube. The analyzed gas rarefaction conditions vary from near free molecular to slip regime. Finally, Poiseuille counter flows consistent with the experimental zero flow conditions of the thermal transpiration process are proved to be possible.

Rojas-Cárdenas, Marcos; Graur, Irina; Perrier, Pierre; Méolans, J. Gilbert

2013-07-01

167

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

PubMed Central

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

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

2007-01-01

168

Effect of a chemical manufacturing plant on community cancer rates  

Microsoft Academic Search

BACKGROUND: We conducted a retrospective study to determine if potential past exposure to dioxin had resulted in increased incidence of cancer in people living near a former manufacturing plant in New South Wales, Australia. During operation, from 1928 to 1970, by-products of the manufacturing process, including dioxin and other chemical waste, were dumped into wetlands and mangroves, discharged into a

Trish Mannes; Katy Emmett; Alan Willmore; Tim Churches; Vicky Sheppeard; Jill Kaldor

2005-01-01

169

The influence of prey capture on photosynthetic rate in two aquatic carnivorous plant species  

Microsoft Academic Search

Photosynthetic (PN) and dark respiration rate (RD) were measured in two species of aquatic carnivorous plants, Aldrovanda vesiculosa and Utricularia australis, growing with or without prey in an outdoor growth experiment. After 7–14 days, the positive growth effect of feeding on prey (apical growth rate, plant size, branching) was evident in both species. Tissue N content in young leaf whorls

Lubomír Adamec

2008-01-01

170

Heat Release Rate Characteristics of Some Combustible Fuel Sources in Nuclear Power Plants.  

National Technical Information Service (NTIS)

A major risk to a nuclear power plant is the possibility of serious fire. There is a need to know the heat release rate behavior of combustible fuels in the plant in order to help reduce the fire threat to the facilities. Heat release rate characteristics...

B. T. Lee

1985-01-01

171

Reduction of tropical land region precipitation variability via transpiration  

NASA Astrophysics Data System (ADS)

Tropical rainforests are known to exhibit low intraseasonal precipitation variability compared with oceanic areas with similar mean precipitation in observations and models. In the present study, the potential role of transpiration for this difference in precipitation variability is investigated using the National Center for Atmospheric Research (NCAR) atmospheric general circulation model. Comparing model results with and without transpiration shows that in the absence of transpiration, mean precipitation decreases as may be expected. However the incidence of both higher daily total column water and more intense precipitation increases without transpiration; consequently the variability of precipitation increases substantially. These results can be understood in terms of the complex interplay of local near-surface and remote moist dynamical processes with both local positive (boundary-layer drying) and large-scale negative (increased large-scale convergence) feedbacks when transpiration is disabled in the model. It is also shown that surface turbulent fluxes over tropical rainforests are highly correlated with incoming solar energy but only weakly correlated with wind speed, possibly decoupling land precipitation from large-scale disturbances like the Madden-Julian Oscillation.

Lee, Jung-Eun; Lintner, Benjamin R.; Neelin, J. David; Jiang, Xianan; Gentine, Pierre; Boyce, C. Kevin; Fisher, Joshua B.; Perron, J. Taylor; Kubar, Terence L.; Lee, Jeonghoon; Worden, John

2012-10-01

172

EVAPOTRANSPIRATION, CANOPY TEMPERATURE, AND PLANT WATER RELATIONS  

Technology Transfer Automated Retrieval System (TEKTRAN)

Because elevated concentrations of CO2 cause partial stomatal closure, transpiration from plant leaves is reduced, which has many ramifications for plant water relations. First, the reduction in leaf transpiration reduces evaporative cooling with a consequential rise in canopy temperatures. Increa...

173

Molecular Rates Parallel Diversification Contrasts between Carnivorous Plant Sister Lineages  

Microsoft Academic Search

In the carnivorous plant family Lentibulariaceae, the bladderwort lineage (Utricularia and Genlisea) is substantially more species-rich and morphologically divergent than its sister lineage, the butterworts (Pinguicula). Bladderworts have a relaxed body plan that has permitted the evolution of terrestrial, epiphytic, and aquatic forms that capture prey in intricately designed suction bladders or corkscrew-shaped lobster-pot traps. In contrast, the flypaper-trapping butterworts

Richard W. Jobson; Victor A. Albert

2002-01-01

174

25-50% rate hikes due from troubled N-plants  

SciTech Connect

The costs of building, deferring, and cancelling nuclear power plants will raise the rates of some utilities from 25 to 50% in the next year or two, although a threatened coal miners' strike could also add from 10 to 15% to the rates of utilities using union coal. A summary of the situation in six regions indicates that most nuclear plant-related rate hikes will occur in the Northeast, Mid-Atlantic, and South Central regions. The article identifies 20 troubled nuclear plants responsible for the push on rates.

Not Available

1984-05-21

175

Inheritance of evapotranspiration and transpiration efficiencies in diallel F 1 hybrids of durum wheat ( Triticum turgidum L. var. durum )  

Microsoft Academic Search

Inheritance of water use and transpiration efficiency was studied in diallel F1 hybrids from six cultivars of T. durum, selected for their different responses to drought stress. Plants were grown in 10 l pots at optimal (control) and low soil\\u000a moisture levels in the glasshouse. GCA and SCA effects were significant at both soil moisture levels. Results demonstrated\\u000a that evapotranspiration

K. F. Solomon; M. T. Labuschagne

2004-01-01

176

Changes in relative growth rate with plant ontogeny in spring wheat genotypes grown as isolated plants  

Microsoft Academic Search

For a better insight in the effect of wide spacing on the outcome of plant selection in spring wheat, the growth of free-grown individual plants was followed in time for each of 12 cultivars. As time proceeded, the cultivar differences for per-plant weight showed progressively less relation with those for seedling weight. At anthesis, the genetic correlation with seedling weight

C. J. T. Spitters; Th. Kramer

1985-01-01

177

Evaluating a Model of Evaporation and Transpiration with Observations in a Partially Wet Douglas-Fir Forest  

NASA Astrophysics Data System (ADS)

The Penman-Monteith equation is extended to describe evaporation of intercepted rain, transpiration and the interaction between these processes in a single explicit function. This single-layer model simulates the effects of heat exchange, stomatal blocking and changed humidity deficit close to the canopy as a function of canopywater storage. Evaporation depends on the distribution of water over the canopy and the energy exchange between wet and dry parts. Transpiration depends on the dry canopy surface resistance that is described with a Jarvis-type response. The explicit functions obtained for water vapour fluxes facilitate a straightforward identificationof the various processes. Canopy water storage amounts and xylem sapflow were measured simultaneously during drying episodes after rainfall in a dense, partially wet, Douglas-fir forest. Estimates of evaporation and transpiration rates are derived from these observations. The analysis shows that evaporation induced transpirationreduction is mainly caused by energy consumption. Changes in water vapour deficit have a minor effect due to a compensating stomatal reaction. The remaining difference between observed and modelled transpiration reduction can be attributed to partial blocking of stomata by the water layer.

Bosveld, Fred C.; Bouten, Willem

178

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

SciTech Connect

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

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

1998-12-31

179

The Control of Transpiration. Insights from Arabidopsis  

Microsoft Academic Search

Stomatal complexes in the epidermes of aerial plant parts are critical sites for the regulation of gas ex- change between the plant and the atmosphere. Sto- mata consist of microscopic pores, each flanked by a pair of guard cells. Guard cells can increase or de- crease the size of the pore via changes in their turgor status, hence regulating both

Sarah E. Nilson; Sarah M. Assmann

2006-01-01

180

Root controls on water redistribution and carbon uptake in the soil-plant system under current and future climate  

NASA Astrophysics Data System (ADS)

Understanding photosynthesis and plant water management as a coupled process remains an open scientific problem. Current eco-hydrologic models characteristically describe plant photosynthetic and hydraulic processes through ad hoc empirical parameterizations with no explicit accounting for the main pathways over which carbon and water uptake interact. Here, a soil-plant-atmosphere continuum model is proposed that mechanistically couples photosynthesis and transpiration rates, including the main leaf physiological controls exerted by stomata. The proposed approach links the soil-to-leaf hydraulic transport to stomatal regulation, and closes the coupled photosynthesis-transpiration problem by maximizing leaf carbon gain subject to a water loss constraint. The approach is evaluated against field data from a grass site and is shown to reproduce the main features of soil moisture dynamics and hydraulic redistribution. In particular, it is shown that the differential soil drying produced by diurnal root water uptake drives a significant upward redistribution of moisture both through a conventional Darcian flow and through the root system, consistent with observations. In a numerical soil drying experiment, it is demonstrated that more than 50% of diurnal transpiration is supplied by nocturnal upward water redistribution, and some 12% is provided directly through root hydraulic redistribution. For a prescribed leaf area density, the model is then used to diagnose how elevated atmospheric CO2 concentration and increased air temperature jointly impact soil moisture, transpiration, photosynthesis, and whole-plant water use efficiency, along with compensatory mechanisms such as hydraulic lift using several canonical forms of root-density distribution.

Volpe, V.; Marani, M.; Albertson, J. D.; Katul, G.

2013-10-01

181

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

182

Forest fire effects on transpiration: process modeling of sapwood area reduction  

Microsoft Academic Search

Transpiration is a hydrological process that is strongly affected by forest fires. In crown fires, canopy fine fuels (foliage, buds, and small branches) combust, which kills individual trees and stops transpiration of the entire stand. In surface fires (intensities <= 2500 kW m-1), however, effects on transpiration are less predictable becuase heat transfer from the passing fireline can injure or

Sean Michaletz; Edward Johnson

2010-01-01

183

A simple method for estimating water loss by transpiration in wetlands  

Microsoft Academic Search

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

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

184

Predicting transpiration from forest stands in Belgium for the 21st century  

Microsoft Academic Search

Canopy transpiration is a major element of the hydrological cycle of temperate forests. Levels of water stress during the 21st century will be largely controlled by the response of canopy transpiration to changing environmental conditions. One year of transpiration measurement in two stands (Quercus robur L. and Fagus sylvatica L.) was used to calibrate the ASPECTS model on a1 and

Laurent Misson; Daniel P Rasse; Caroline Vincke; Marc Aubinet; Louis François

2002-01-01

185

A simple method to determine transpiration efficiency in sorghum  

Technology Transfer Automated Retrieval System (TEKTRAN)

[Sorghum bicolor (L.) Moench] is a widely-grown cereal grain and a dietary staple for more than 500 million people worldwide, grown primarily in arid and semi-arid regions. Crop modeling analysis indicates that a small improvement in transpiration efficiency (TE) could have a large impact on sorghu...

186

CONTROLS ON TRANSPIRATION IN A DESERT RIPARIAN COTTONWOOD FOREST 1764  

Technology Transfer Automated Retrieval System (TEKTRAN)

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

187

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

SciTech Connect

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

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

1995-09-01

188

Evaluating Uncertainties in Sap Flux Scaled Estimates of Forest Transpiration, Canopy Conductance and Photosynthesis  

NASA Astrophysics Data System (ADS)

Thermal dissipation probes (TDPs) are a common method for estimating forest transpiration and canopy conductance from sap flux rates in trees, but their implementation is plagued by uncertainties arising from missing data and variability in the diameter and canopy position of trees, as well as sapwood conductivity within individual trees. Uncertainties in estimates of canopy conductance also translate into uncertainties in carbon assimilation in models such as the Canopy Conductance Constrained Carbon Assimilation (4CA) model that combine physiological and environmental data to estimate photosynthetic rates. We developed a method to propagate these uncertainties in the scaling and imputation of TDP data to estimates of canopy transpiration and conductance using a state-space Jarvis-type conductance model in a hierarchical Bayesian framework. This presentation will focus on the impact of these uncertainties on estimates of water and carbon fluxes using 4CA and data from the Duke Free Air Carbon Enrichment (FACE) project, which incorporates both elevated carbon dioxide and soil nitrogen treatments. We will also address the response of canopy conductance to vapor pressure deficit, incident radiation and soil moisture, as well as the effect of treatment-related stand structure differences in scaling TDP measurements. Preliminary results indicate that in 2006, a year of normal precipitation (1127 mm), canopy transpiration increased in elevated carbon dioxide ~8% on a ground area basis. In 2007, a year with a pronounced drought (800 mm precipitation), this increase was only present in the combined carbon dioxide and fertilization treatment. The seasonal dynamics of water and carbon fluxes will be discussed in detail.

Ward, E. J.; Bell, D. M.; Clark, J. S.; Kim, H.; Oren, R.

2009-12-01

189

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

USGS Publications Warehouse

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

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

2011-01-01

190

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

Microsoft Academic Search

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

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

1991-01-01

191

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

2013-01-18

192

The death of Canadian manufacturing plants: heterogeneous responses to changes in tariffs and real exchange rates  

Microsoft Academic Search

We examine simultaneously the effects of real-exchange-rate movements and tariff reductions on plant death in Canadian manufacturing\\u000a industries between 1979 and 1996. Consistent with the implications of recent international trade models with heterogeneous\\u000a firms, we find that the impact of exchange-rate movements and tariff cuts on exit is heterogeneous—particularly pronounced\\u000a among least efficient plants. Our results further reveal multi-dimensional heterogeneity

John R. Baldwin; Beiling Yan

2011-01-01

193

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

194

Small variance in growth rates in annual plants has large effects on genetic drift.  

PubMed

• Premise of the Study: Effective population size (N(e)) is a critical index of the evolutionary capacity of populations. Low N(e) indicates that standing genetic diversity is susceptible to loss via stochastic processes (and inbreeding) and is, therefore, unavailable for natural selection to act upon. Reported N(e) in plant populations is often quite low. What biological and ecological factors might produce such low N(e) • Methods: We conducted a simulation model to test the effect of randomly assigned and autocorrelated growth rates of annual plants on plant-size distributions at the end of the growing season. Because plant size is directly correlated with reproductive output in annual plants, variation in plant size reflects variation in reproduction, and thus our modeled size distributions can be used to estimate N(e). • Key Results: Randomly assigned growth rates had a negligble effect on N(e)/N. Autocorrelated growth rates decreased N(e)/N as the length of the growing season increased. This was the case even when the variance in growth rates was as low as 0.1% of the mean. • Conclusions: While intrinsic plant biology can affect the degree of growth autocorrelation, ecological factors such as competition, herbivory, and abiotic stress can increase or decrease levels of growth autocorrelation. Ecological factors that increase growth autocorrelation can have significant effects on genetic drift within populations. PMID:21616892

Espeland, Erin K; O'Farrell, Michael R

2010-07-20

195

The mechanism of thermal transpiration (= thermal osmosis)  

Microsoft Academic Search

Floating-leaved aquatic plants have acquired a convective gas-throughflow system to supply oxygen from the atmosphere to their roots and rhizomes growing in anoxic sediments of shallow lakes and are dependent upon an efficient internal aeration. Tissue layers with minute pores inside the newly-emergent leaves, separating the aerenchyma of the leaves from the ambient atmosphere, create a pressurised ventilation by both

Wolfgang Große

1996-01-01

196

Allelopathic Monoterpenes Interfere with Arabidopsis thaliana Cuticular Waxes and Enhance Transpiration  

PubMed Central

Exposure to the allelopathic monoterpenes camphor (100 mg/10 L) and menthol (50 mg/10 L) for 24 h enhanced transpiration of Arabidopsis thaliana fully developed rosette leaves similar to de-waxing. As ascertained by ESEM analyses the leaf surfaces were spotted with platelet like structures which seem to be partly mixed with the lipophilic epicuticular layers. The structures are supposed to contain the condensed monoterpenes, which could be identified by GC. Long term exposure (more than 48 h) to 100 mg/50 mg killed the plants by desiccation, a 24 h exposure caused necrotic spots that became visible one to two days after the treatment. Examinations of the stomatal apertures indicated that monoterpenes induced stomatal opening followed by extreme swelling and a final break down of the protoplasts. Exposure of Arabidopsis thaliana to volatiles of Mentha piperita, Lavandula latifolia and Artemisia camphorata resulted in a dramatic increase of the stomata aperture but swelling of the protoplasts was less exhibited. In contrast to de-waxing, expression of the fatty acid condensing enzyme encoding CER6 gene and de novo synthesis of CER6 protein was not induced after 24 h of exposure to the monoterpenes. The aim of the study was to demonstrate that the lipophilic layers of the leaf surface and the stomata are primary targets of monoterpene allelopathic attack. Enhanced transpiration results from a combination of affected lipophilic wax layers and a disturbed stomata function.

Kussmann, Petra; Knop, Mona; Kriegs, Bettina; Gresens, Frank; Eichert, Thomas; Ulbrich, Andreas; Marx, Friedhelm; Fabricius, Heinz; Goldbach, Heiner; Noga, Georg

2007-01-01

197

Canopy Photosynthesis and Transpiration in Micro-Gravity: Gas Exchange Measurements Aboard MIR  

NASA Astrophysics Data System (ADS)

The SVET Greenhouse on-board the Orbital Station Mir was used to measure canopy photosynthesis and transpiration rates for the first time in space. During the Greenhouse IIB experiment on Mir (June - January 1997), carbon and water vapor fluxes from two wheat (cv. Superdwarf) canopies were measured using the US developed Gas Exchange Measurement System (GEMS). Gas analyzers capable of resolving CO2 concentration differences of 5 ?mol mol-1 against a background of 0.9% CO2, are necessary to measure photosynthetic and respiratory rates on Mir. The ability of the GEMS gas analyzers to measure these CO2 concentration differences was determined during extensive ground calibrations. Similarly, the sensitivity of the analyzers to water vapor was sufficient to accurately measure canopy evapotranspiration. Evapotranspiration, which accounted for over 90% of the water added to the root zone, was estimated using gas exchange and used to estimate substrate moisture content. This paper presents canopy photosynthesis and transpiration data during the peak vegetative phase of development in microgravity

Monje, O.; Bingham, G. E.; Carman, J. G.; Campbell, W. F.; Salisbury, F. B.; Eames, B. K.; Sytchev, V.; Levinskikh, M. A.; Podolsky, I.

198

Canopy photosynthesis and transpiration in microgravity: gas exchange measurements aboard Mir.  

PubMed

The SVET Greenhouse on-board the Orbital Station Mir was used to measure canopy photosynthesis and transpiration rates for the first time in space. During the Greenhouse IIB experiment on Mir (June-January 1997), carbon and water vapor fluxes from two wheat (cv. Superdwarf) canopies were measured using the US developed Gas Exchange Measurement System (GEMS). Gas analyzers capable of resolving CO2 concentration differences of 5 micromoles mol-1 against a background of 0.9% CO2, are necessary to measure photosynthetic and respiratory rates on Mir. The ability of the GEMS gas analyzers to measure these CO2 concentration differences was determined during extensive ground calibrations. Similarly, the sensitivity of the analyzers to water vapor was sufficient to accurately measure canopy evapotranspiration. Evapotranspiration, which accounted for over 90% of the water added to the root zone, was estimated using gas exchange and used to estimate substrate moisture content. This paper presents canopy photosynthesis and transpiration data during the peak vegetative phase of development in microgravity. PMID:11543166

Monje, O; Bingham, G E; Carman, J G; Campbell, W F; Salisbury, F B; Eames, B K; Sytchev, V; Levinskikh, M A; Podolsky, I

2000-01-01

199

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

PubMed Central

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

2013-01-01

200

Heat transfer of rhyniophytic plant axes  

Microsoft Academic Search

Heat transfer is important for plants being sedentary organisms and exposed fully or partly to direct sunlight. It comprises three different mechanisms: (1) emission of IR (infra-red) radiation, (2) heat conduction and convection (sensible heat) and (3) evaporative cooling by transpiration (latent heat). Transpiration has been shown to act as an efficient cooling device in the case of extant land

Anita Roth-Nebelsick

2001-01-01

201

Visualization of early stress responses in plant leaves  

Microsoft Academic Search

Plant leaves possess microscopic valves, called stomata, that enable control of transpirational water loss. In case of water shortage, stomata close, resulting in decreased transpirational cooling. The ensuing temperature increase is readily visualized by thermography. Salicylic acid, a central compound in the defense of plants against pathogens, also closes stomata in several species. In previous work, thermography permitted to monitor

Laury Chaerle; Martin J. vande Ven; Roland L. Valcke; Dominique Van Der Straeten

2002-01-01

202

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

203

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

2009-10-09

204

The Rate and Spectrum of Spontaneous Mutations in a Plant RNA Virus  

PubMed Central

Knowing mutation rates and the molecular spectrum of spontaneous mutations is important to understanding how the genetic composition of viral populations evolves. Previous studies have shown that the rate of spontaneous mutations for RNA viruses widely varies between 0.01 and 2 mutations per genome and generation, with plant RNA viruses always occupying the lower side of this range. However, this peculiarity of plant RNA viruses is based on a very limited number of studies. Here we analyze the spontaneous mutational spectrum and the mutation rate of Tobacco etch potyvirus, a model system of positive sense RNA viruses. Our experimental setup minimizes the action of purifying selection on the mutational spectrum, thus giving a picture of what types of mutations are produced by the viral replicase. As expected for a neutral target, we found that transitions and nonsynonymous (including a few stop codons and small deletions) mutations were the most abundant type. This spectrum was notably different from the one previously described for another plant virus. We have estimated that the spontaneous mutation rate for this virus was in the range 10?6?10?5 mutations per site and generation. Our estimates are in the same biological ballpark that previous values reported for plant RNA viruses. This finding gives further support to the idea that plant RNA viruses may have lower mutation rates than their animal counterparts.

Tromas, Nicolas; Elena, Santiago F.

2010-01-01

205

A prototype photovoltaic\\/thermal system integrated with transpired collector  

Microsoft Academic Search

Building-integrated photovoltaic\\/thermal (BIPV\\/T) systems may be utilized to produce useful heat while simultaneously generating electricity from the same building envelope surface. A well known highly efficient collector is the open-loop unglazed transpired collector (UTC) which consists of dark porous cladding through which outdoor air is drawn and heated by absorbed solar radiation. Commercially available photovoltaic systems typically produce electricity with

Andreas K. Athienitis; James Bambara; Brendan ONeill; Jonathan Faille

2011-01-01

206

Nighttime transpiration observed over a larch forest in Hokkaido, Japan  

Microsoft Academic Search

Nighttime transpiration in a larch forest in northern Japan was investigated using concurrent measurements of the energy budget below and above the canopy and sap flow velocities. Upward latent heat flux (lE) above the canopy was observed on ?20% of nights during the growing season. Nighttime lE was ?7% of daily totals during the dry season (September–October) and averaged ?3%

N. Kobayashi; T. Hiyama; Y. Fukushima; M. L. Lopez; T. Hirano; Y. Fujinuma

2007-01-01

207

Analytical study of turbulent Poiseuille flow with wall transpiration  

NASA Astrophysics Data System (ADS)

An incompressible, pressure-driven, fully developed turbulent flow between two parallel walls, with an extra constant transverse velocity component, is considered. A closure condition is formulated, which relates the shear stress to the first and the second derivatives of the longitudinal mean velocity. The closure condition is derived without invoking any special hypotheses on the nature of turbulent motion, only taking advantage of the fact that the flow depends on a finite number of governing parameters. By virtue of the closure condition, the momentum equation is reduced to the boundary-value problem for a second-order differential equation, which is solved by the method of matched asymptotic expansions at high values of the logarithm of the Reynolds number based on the friction velocity. There are three characteristic flow regions in the channel: the core region and two wall regions near injection and suction walls. For each region, the solution is constructed. The asymptotic matching gives formulas for the wall shear stress and the maximum mean velocity. A limit transpiration velocity is obtained, such that the shear stress at the injection wall vanishes, while the maximum point on the velocity profile approaches the suction wall. In this case, a sublayer near the suction wall appears where the mean velocity is proportional to the square root of the distance from the wall. A friction law for Poiseuille flow with transpiration is found, which makes it possible to describe the relation between the wall shear stress, the Reynolds number, and the transpiration velocity by a function of one variable. A velocity defect law, which generalizes the classical law for the core region in a channel with impermeable walls to the case of transpiration, is also established. In similarity variables, the mean velocity profiles across the whole channel width outside viscous sublayers can be described by a one-parameter family of curves. The theoretical results obtained are in good agreement with available direct numerical simulation data.

Vigdorovich, Igor; Oberlack, Martin

2008-05-01

208

Porous Ceramic Coating for Transpiration Cooling of Gas Turbine Blade  

NASA Astrophysics Data System (ADS)

A transpiration cooling system for gas turbine applications has significant benefit for reducing the amount of cooling air and increasing cooling efficiency. In this paper, the porous ceramic coating, which can infiltrate cooling gas, is developed with plasma spraying process, and the properties of the porous coating material such as permeability of cooling gas, thermal conductivity, and adhesion strength are examined. The mixture of 8 wt.% yttria-stabilized zirconia and polyester powders was employed as the coating material, in order to deposit the porous ceramic coating onto Ni-based super alloy substrate. It was shown that the porous ceramic coating has superior permeability for cooling gas. The adhesion strength of the porous coating was low only 20% compared with the thermal barrier coating utilized in current gas turbine blades. Simulation test of hot gas flow around the gas turbine blade verified remarkable reduction of the coating surface temperature by the transpiration cooling mechanism. It was concluded that the transpiration cooling system for the gas turbine could be achieved using the porous ceramic coating developed in this study.

Arai, M.; Suidzu, T.

2013-06-01

209

Plant Growth-Promoting Rhizobacteria Allow Reduced Application Rates of Chemical Fertilizers  

Microsoft Academic Search

The search for microorganisms that improve soil fertility and enhance plant nutrition has continued to attract attention due\\u000a to the increasing cost of fertilizers and some of their negative environmental impacts. The objectives of this greenhouse\\u000a study with tomato were to determine (1) if reduced rates of inorganic fertilizer coupled with microbial inoculants will produce\\u000a plant growth, yield, and nutrient

A. O. Adesemoye; H. A. Torbert; J. W. Kloepper

2009-01-01

210

Influence of seed rates and row spacings on the growth and yield of late planted sugarcane  

Microsoft Academic Search

A field experiment was conducted to see the effect of seed rates and row spacings on the growth and yield of late planted\\u000a sugarcane at Regional Research Station, Kheri (Sangrur) during 1995–96 and 1996–97. Pooled data of plant and ratoon crop on\\u000a cane yield, tillers, millable canes and cane height revealed that significantly higher cane yield was obtained from the

Avtar Singh

2000-01-01

211

Relationship between calcium decoding elements and plant abiotic-stress resistance  

PubMed Central

Serving as an important second messenger, calcium ion has unique properties and universal ability to transmit diverse signals that trigger primary physiological actions in cells in response to hormones, pathogens, light, gravity, and stress factors. Being a second messenger of paramount significance, calcium is required at almost all stages of plant growth and development, playing a fundamental role in regulating polar growth of cells and tissues and participating in plant adaptation to various stress factors. Many researches showed that calcium signals decoding elements are involved in ABA-induced stomatal closure and plant adaptation to drought, cold, salt and other abiotic stresses. Calcium channel proteins like AtTPC1 and TaTPC1 can regulate stomatal closure. Recently some new studies show that Ca2+ is dissolved in water in the apoplast and transported primarily from root to shoot through the transpiration stream. The oscillating amplitudes of [Ca2+]o and [Ca2+]i are controlled by soil Ca2+ concentrations and transpiration rates. Because leaf water use efficiency (WUE) is determined by stomatal closure and transpiration rate, so there may be a close relationship between Ca2+ transporters and stomatal closure as well as WUE, which needs to be studied. The selection of varieties with better drought resistance and high WUE plays an increasing role in bio-watersaving in arid and semi-arid areas on the globe. The current paper reviews the relationship between calcium signals decoding elements and plant drought resistance as well as other abiotic stresses for further study.

Song, Wei-Yi; Zhang, Zheng-Bin; Shao, Hong-Bo; Guo, Xiu-Lin; Cao, Hong-Xing; Zhao, Hong-Bin; Fu, Zheng-Yan; Hu, Xiao-Jun

2008-01-01

212

Physical effects of dust on leaf physiology of cucumber and kidney bean plants.  

PubMed

The physical effects of dust accumulating on leaf surfaces, on leaf physiology, such as photosynthesis, transpiration, stomatal conductance and leaf temperature of cucumber and kidney bean plants were investigated by the use of chemically inert dust. It was found that dust decreased stomatal conductance in the light, and increased it in the dark by plugging the stomata, when the stomata were open during dusting. When dust of smaller particles was applied, the effect was greater. However, the effect was negligible when the stomata were closed during dusting. The dust decreased the photosynthetic rate by shading the leaf surface. The dust of smaller particles had a greater shading effect. Moreover, it was found that the additional absorption of incident radiation by the dust increased the leaf temperature, and consequently changed the photosynthetic rate in accordance with its response curve to leaf temperature. The increase in leaf temperature also increased the transpiration rate. PMID:15091515

Hirano, T; Kiyota, M; Aiga, I

1995-01-01

213

Transpiration and water use efficiency in native chilean and exotic species, a usefull tool for catchment management?  

NASA Astrophysics Data System (ADS)

Land-use and forest cover change play important roles in socio-economic processes and have been linked with water supply and other ecosystem services in various regions of the world. Water yield from watersheds is a major ecosystem service for human activities but has been altered by landscape management superimposed on climatic variability and change. Sustaining ecosystem services important to humans, while providing a dependable water supply for agriculture and urban needs is a major challenge faced by managers of human-dominated or increased antropical effect over watersheds. Since water is mostly consumed by vegetation (i.e: transpiration), which strongly depends on trees physiological characteristics (i.e: foliar area, transpiration capacity) are very important. The quantity of water consumed by plantations is influenced mainly by forest characteristics (species physiology, age and management), catchment water retention capacity and meteorological characteristics. Eventhough in Chile, the forest sector accounts for 3.6% of the gross domestic product (GDP) and 12.5% of total exports (INFOR, 2003), afforestation with fast growing exotic species has ended up being socially and politically questionable because of the supposed impact on the environment and water resources. We present data of trees transpiration and water use efficiency from three headwater catchments: (a) second growth native evergreen forest (Aetoxicon punctatum, Drimys winterii, Gevuina avellana, Laureliopsis philippiana); (b) Eucalyptus globulus plantation, and (c) a mixed native deciduous (Nothofagus obliqua and some evergreen species) forest and Eucalyptus globulus and Acacia melanoxylon plantation located at the Coastal Mountain Range in southern Chile (40°S). Annual transpiration rates ranged from 1.24 ± 0.41 mol•m-2•s-1 (0.022 ± 0.009 L•m-2•s-1) for E. globulus, while the lowest observed was for L. philippiana 0.44 ± 0.31 mol•m-2•s-1 (0.008 ± 0.006 L•m-2•s-1). However water use efficiency for E. globulus, was the lowest observed (6.78 ± 8.92 ?mol•mol-1) compared to native species, 7.45 ± 4.41 ?mol•mol-1 for A. punctatum which showed the lowest value (p < 0.05). Preliminary results show, that the E. globulus has the highest transpiration rate, but the lowest water use efficiency values, compared to native evergreen and deciduous species. Nevertheless E. globulus showed the highest photosyntethic rate values, which finally traduces that E. globulus is a fast growing, big water drinker but it's less efficient than most native trees used in this experiment. Acknowledges This research has been supported by FONDECYT 1090345. Mr. Hervé-Fernández wishes to thank BECAS CHILE for his scholarship.

Hervé-Fernández, P.; Oyarzun, C. E.

2012-04-01

214

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

PubMed

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

2013-06-19

215

RETRAN-02 comparison of natural circulation flow rates at Babcock and Wilcox 177FA plants  

Microsoft Academic Search

A very important aspect of nuclear steam supply system (NSSS) model development is the process of comparing the computer model results against actual plant responses. Good comparisons will qualify the computer model for specific engineering analyses. Flow rates and decay heat power levels were obtained from planned and unplanned natural circulation events that occurred at Arkansas Nuclear One, Crystal River,

Simms

1985-01-01

216

Soybean Photosynthetic Rate and Carbon Fixation at Early and Late Planting Dates  

Technology Transfer Automated Retrieval System (TEKTRAN)

Early planting (late April to early May) is recommended for increasing soybean yield but a full understanding of the physiological response is lacking. This study was conducted to determine whether carbon dioxide exchange rate (CER) could explain this yield difference. A study with five (2007) and s...

217

RATE OF TCE DEGRADATION IN PASSIVE REACTIVE BARRIERS CONSTRUCTED WITH PLANT MULCH (BIOWALLS)  

EPA Science Inventory

This presentation reviews a case study at Altus AFB on the extent of treatment of TCE in a passive reactive barrier constructed with plant mulch. It presents data from a tracer test to estimate the rate of ground water flow at the site, and the residence time of water and TCE in...

218

Planting date rate and twin-row vs single-row soybean in the mid south  

Technology Transfer Automated Retrieval System (TEKTRAN)

Comparisons of twin-row vs. single-row production of an irrigated MG IV soybean (Glycine max (L.) Merr.) on a sandy loam soil and a clay indigenous to the Mississippi Delta were conducted in 2009 to 2010 at Stoneville, MS. Seeding rates of 20, 30, 40, and 50 seed m-2 were planted in four row plots ...

219

Chilling rate effects on pork loin tenderness in commercial processing plants  

Technology Transfer Automated Retrieval System (TEKTRAN)

The present experiment was conducted to provide a large-scale objective comparison of pork LM tenderness and other meat quality traits between packing plants that differ in stunning method and carcass chilling rate. For each of two replicates, hogs were sourced from a single barn of a commercial fi...

220

Cancer Morbidity Rates of Children from the Vicinity of the Nuclear Power Plant of Würgassen (FRG)  

Microsoft Academic Search

The morbidity rates from neoplastic disease have been studied in children below the age of 15 years, residing at the time of their diagnosis within a diameter of 25 km of the nuclear power plant of Würgassen (FRG). A total of 42 patients were registered between the years of 1980 and 1988:15 patients with neoplasms of the hematolymphopoietic system, 14

G. Prindull; M. Demuth; H. Wehinger

1993-01-01

221

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.

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

2008-01-01

222

Determining water use by trees and forests from isotopic, energy balance and transpiration analyses: the roles of tree size and hydraulic lift.  

PubMed

Use of soil water and groundwater by open-grown Acer saccharum Marsh. (sugar maple) tree canopies and forests was estimated by measuring transpiration (E) rates using porometry, sap flow methods, and the Bowen ratio method. The Bowen ratio and sap flow methods showed the best agreement; porometer measurements scaled to whole canopies always underestimated E by 15-50%. Trees of different sizes showed very different rates of E. I hypothesized that these differences were due to the differential access of large and small trees to groundwater and soil water, respectively. Transpirational flux was partitioned between soil water and groundwater by tracing the water sources based on their hydrogen stable isotopic composition (deltaD). Soil water deltaD varied between -41 and -16 per thousand seasonally (May to September), whereas groundwater deltaD was -79 +/- 5 per thousand during the entire growing season. Daily transpiration rates of large (9-14 m tall) trees were significantly higher than those of small (3-5 m tall) trees (2.46-6.99 +/- 1.02-2.50 versus 0.69-1.80 +/- 0.39-0.67 mm day(-1)). Small trees also showed greater variation in E during the growing season than large trees. In addition, compared to the large trees, small trees demonstrated greater sensitivity to environmental factors that influence E, such as soil water deficits and increased evaporative demand. Over the entire growing season, large trees and forest stands composed of trees > 10 m tall transpired only groundwater. The high rates of water loss from large trees and older forests were likely a result of the influence of an enhanced "pool" of transpirational water in the upper soil layers caused by hydraulic lift (see Dawson 1993b). The hydraulically lifted water reservoir enabled large trees to use more potential transpirational water during daylight hours than small trees, leading to a greater total water flux. In contrast, small trees and forest stands composed of younger trees almost exclusively used soil water, except during two dry periods when their transpirational water was composed of between 7 and 17% groundwater. Thus groundwater discharge from sugar maple trees and forest stands of different sizes (ages) differs significantly, and large trees and older forest stands have a greater impact on the hydrologic balance of groundwater than small trees and younger forest stands. However, mixed stands (small and large trees) may have a greater overall impact on the regional hydrologic balance than old stands, because trees in mixed stands draw on both soil water and groundwater reservoirs and thus can substantially increase total water discharge on scales from tens to hundreds of hectares. PMID:14871771

Dawson, Todd E.

223

Indel-associated mutation rate varies with mating system in flowering plants.  

PubMed

A recently proposed mutational mechanism, indel-associated mutation (IDAM), posits that heterozygous insertions/deletions (indels) increase the point mutation rate at nearby nucleotides due to errors during meiosis. This mechanism could have especially dynamic consequences for the evolution of plant genomes, because the high degree of variation in the rate of self-fertilization among plant species causes differences in the heterozygosity of alleles, including indel alleles, segregating in plant species. In this study, we investigated the consequences of IDAM for species differing in mating system using both forward population genetic simulations and genomewide DNA resequencing data from Arabidopsis thaliana, Oryza sativa, and Oryza rufipogon. Simulations of different levels of selfing suggest that the effect of IDAM on surrounding nucleotide diversity should decrease with increasing selfing rate. Further simulations incorporating selfing rates and the time of onset of selfing suggest that the time since the switch to selfing also affects patterns of nucleotide diversity due to IDAM. Population genetic analyses of A. thaliana and Oryza DNA sequence data sets empirically confirmed our simulation results, revealing the strongest effect of IDAM in the outcrossing O. rufipogon, a weaker effect in the recently evolved selfer O. sativa, and the weakest effect in the relatively ancient selfer A. thaliana. These results support the novel idea that differences in life history, such as the level of selfing, can affect the per-individual mutation rate among species. PMID:19825943

Hollister, Jesse D; Ross-Ibarra, Jeffrey; Gaut, Brandon S

2009-10-13

224

Plant gas exchange at high wind speeds  

Microsoft Academic Search

High altitude Rhododendron ferrugineum L. and Pinus cembra L. seedlings were exposed to winds at 15 meters per second for 24-hour periods. Wind-sensitive stomata of Rhododendron seedlings immediately initiated a closing response which resulted in decreased photosynthesis and an even greater reduction in transpiration. Stomatal aperture and transpiration rates of P. cembra were only slightly reduced by high speed winds.

M. M. Caldwell

1970-01-01

225

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

226

Invariant scaling relationships for interspecific plant biomass production rates and body size  

PubMed Central

The allometric relationships for plant annualized biomass production (“growth”) rates, different measures of body size (dry weight and length), and photosynthetic biomass (or pigment concentration) per plant (or cell) are reported for multicellular and unicellular plants representing three algal phyla; aquatic ferns; aquatic and terrestrial herbaceous dicots; and arborescent monocots, dicots, and conifers. Annualized rates of growth G scale as the 3/4-power of body mass M over 20 orders of magnitude of M (i.e., G ? M3/4); plant body length L (i.e., cell length or plant height) scales, on average, as the 1/4-power of M over 22 orders of magnitude of M (i.e., L ? M1/4); and photosynthetic biomass Mp scales as the 3/4-power of nonphotosynthetic biomass Mn (i.e., Mp ? Mn3/4). Because these scaling relationships are indifferent to phylogenetic affiliation and habitat, they have far-reaching ecological and evolutionary implications (e.g., net primary productivity is predicted to be largely insensitive to community species composition or geological age).

Niklas, Karl J.; Enquist, Brian J.

2001-01-01

227

Genome-wide investigation reveals high evolutionary rates in annual model plants  

PubMed Central

Background Rates of molecular evolution vary widely among species. While significant deviations from molecular clock have been found in many taxa, effects of life histories on molecular evolution are not fully understood. In plants, annual/perennial life history traits have long been suspected to influence the evolutionary rates at the molecular level. To date, however, the number of genes investigated on this subject is limited and the conclusions are mixed. To evaluate the possible heterogeneity in evolutionary rates between annual and perennial plants at the genomic level, we investigated 85 nuclear housekeeping genes, 10 non-housekeeping families, and 34 chloroplast genes using the genomic data from model plants including Arabidopsis thaliana and Medicago truncatula for annuals and grape (Vitis vinifera) and popular (Populus trichocarpa) for perennials. Results According to the cross-comparisons among the four species, 74-82% of the nuclear genes and 71-97% of the chloroplast genes suggested higher rates of molecular evolution in the two annuals than those in the two perennials. The significant heterogeneity in evolutionary rate between annuals and perennials was consistently found both in nonsynonymous sites and synonymous sites. While a linear correlation of evolutionary rates in orthologous genes between species was observed in nonsynonymous sites, the correlation was weak or invisible in synonymous sites. This tendency was clearer in nuclear genes than in chloroplast genes, in which the overall evolutionary rate was small. The slope of the regression line was consistently lower than unity, further confirming the higher evolutionary rate in annuals at the genomic level. Conclusions The higher evolutionary rate in annuals than in perennials appears to be a universal phenomenon both in nuclear and chloroplast genomes in the four dicot model plants we investigated. Therefore, such heterogeneity in evolutionary rate should result from factors that have genome-wide influence, most likely those associated with annual/perennial life history. Although we acknowledge current limitations of this kind of study, mainly due to a small sample size available and a distant taxonomic relationship of the model organisms, our results indicate that the genome-wide survey is a promising approach toward further understanding of the mechanism determining the molecular evolutionary rate at the genomic level.

2010-01-01

228

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

229

Surface energy balance model of transpiration from variable canopy cover and evaporation from residue-covered or bare soil systems: model evaluation  

Microsoft Academic Search

A surface energy balance model (SEB) was extended by Lagos et al. Irrig Sci 28:51–64 (2009) to estimate evapotranspiration (ET) from variable canopy cover and evaporation from residue-covered or bare soil systems.\\u000a The model estimates latent, sensible, and soil heat fluxes and provides a method to partition evapotranspiration into soil\\/residue\\u000a evaporation and plant transpiration. The objective of this work was

Luis Octavio Lagos; Derrel L. Martin; Shashi B. Verma; Suat Irmak; Ayse Irmak; Dean Eisenhauer; Andrew Suyker

230

Plant-driven variation in decomposition rates improves projections of global litter stock distribution  

NASA Astrophysics Data System (ADS)

Plant litter stocks are critical, regionally for their role in fueling fire regimes and controlling soil fertility, and globally through their feedback to atmospheric CO2 and climate. Here we employ two global databases linking plant functional types to decomposition rates of wood and leaf litter (Cornwell et al., 2008; Weedon et al., 2009) to improve future projections of climate and carbon cycle using an intermediate complexity Earth system model. Implementing separate wood and leaf litter decomposabilities and their temperature sensitivities for a range of plant functional types yielded a more realistic distribution of litter stocks in all present biomes with except of boreal forests and projects a strong increase in global litter stocks and a concomitant small decrease in atmospheric CO2 by the end of this century. Despite a relatively strong increase in litter stocks, the modified parameterization results in less elevated wildfire emissions because of litter redistribution towards more humid regions.

Brovkin, V.; van Bodegom, P. M.; Kleinen, T.; Wirth, C.; Cornwell, W.; Cornelissen, J. H. C.; Kattge, J.

2011-08-01

231

Rep-rated Z-Pinch Power Plant Concept - Direct Energy Conversion and Shrapnel Generation*  

NASA Astrophysics Data System (ADS)

We are developing direct energy conversion schemes and shrapnel generation models to be used to optimize a high yield z-pinch IFE power plant concept. The concept uses high yield ( 10 GJ) at low rep-rate ( 0.1 Hz), with a Recyclable Transmission Line (RTL) to provide the necessary standoff between the fusion target and the power plant chamber. The RTL would be cast out of a conventional power plant coolant material (such as Li or Flibe) that can be used to absorb the fusion energy, breed tritium, and mitigate the shock to the first wall. Current results of initial work on this concept will be discussed. *Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed-Martin Company, for the United States Department of Energy Under Contract DE-AC04-94AL85000.

de Groot, John S.; Gronbech-Jensen, Niels; Miller, Greg; Olsen, Craig L.; Rochau, Gary E.; Derzon, Mark S.; Slutz, Steven A.; Spielman, Rick B.; Peterson, Per F.; Rochau, Gregory A.; Pederson, Robert R.

2000-10-01

232

Mycorrhizal association between the desert truffle Terfezia boudieri and Helianthemum sessiliflorum alters plant physiology and fitness to arid conditions.  

PubMed

The host plant Helianthemum sessiliflorum was inoculated with the mycorrhizal desert truffle Terfezia boudieri Chatin, and the subsequent effects of the ectomycorrhizal relationship on host physiology were determined. Diurnal measurements revealed that mycorrhizal (M) plants had higher rates of photosynthesis (35%), transpiration (18%), and night respiration (49%) than non-mycorrhizal (NM) plants. Consequently, M plants exhibited higher biomass accumulation, higher shoot-to-root ratios, and improved water use efficiency compared to NM plants. Total chlorophyll content was higher in M plants, and the ratio between chlorophyll a to chlorophyll b was altered in M plants. The increase in chlorophyll b content was significantly higher than the increase in chlorophyll a content (2.58- and 1.52-fold, respectively) compared to control. Calculation of the photosynthetic activation energy indicated lower energy requirements for CO(2) assimilation in M plants than in NM plants (48.62 and 61.56 kJ mol(-1), respectively). Continuous measurements of CO(2) exchange and transpiration in M plants versus NM plants provided a complete picture of the daily physiological differences brought on by the ectomycorrhizal relationships. The enhanced competence of M plants to withstand the harsh environmental conditions of the desert is discussed in view of the mycorrhizal-derived alterations in host physiology. PMID:21416258

Turgeman, Tidhar; Asher, Jiftach Ben; Roth-Bejerano, Nurit; Kagan-Zur, Varda; Kapulnik, Yoram; Sitrit, Yaron

2011-03-18

233

The Role of Detailed Land Cover Data on Modeling Transpiration in a Managed Forested Landscape  

NASA Astrophysics Data System (ADS)

Remotely sensed vegetation data is a primary data source for land surface hydrology models. For example, leaf area index (LAI), is widely seen as a key variable in modeling water, carbon, and energy at the land surface. On the other hand, species-specific knowledge of land cover types is often considered less important at the landscape scale. We hypothesize that this assumption might not hold in a managed forest with changing patterns of forest cover types. We tested the significance of site-specific remotely sensed land cover classification for making regional estimates of evapotranspiration in northern Wisconsin, USA. We developed a site-specific land cover classification at 15m resolution using NASA's Airborne Terrestrial Applications Sensor (ATLAS). A field campaign consisted of detailed ground control for image geometry correction and registration, and 324 permanent plots for vegetation cover types and leaf area index and other ecosystem parameters. We then identified four major forest cover types (forested wetland, aspen/fir, northern hardwoods, and conifers) that represent 85 percent of the 100 km2 landscape around our site. In representative stands for each cover type we made continuous sap flux and micrometeorological measurements, from which stand-type parameter sets were developed for use in a regional hydrologic model. Simulated transpiration flux with this detailed model was then compared with a less detailed parameterization based on limited cover type information and BIOME-BGC type parameter values. Disparity between the more aggregated parameter approach and the detailed approach was due to nonlinear mixing of different forest stomatal physiology. For instance, the aspen/fir stands transpire at a rate of 2 mm/day, but northern hardwoods transpire at 1 mm/day, for the same LAI. The results indicate that land cover classification may be as critical as LAI for land surface modeling at large scales. The detailed information could, for example, be combined with coarser global data sets by using site-specific sampling with high-resolution remote sensing data.

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

2001-05-01

234

Boron mobility in plants  

Microsoft Academic Search

In the majority of plant species, B distribution between plant organs and the symptoms of B deficiency and toxicity indicate that B has restricted mobility. Nevertheless, B is present in phloem and is retranslocated in phloem, often in sufficient amounts to satisfy the demands of developing sink regions that do not readily transpire. In species that produce significant amounts of

Barry J. Shelp; Eduardo Marentes; Alice M. Kitheka; Pathmanathan Vivekanandan

1995-01-01

235

Boron mobility in plants  

Microsoft Academic Search

In the majority of plant species, B distribution between plant organs and the symptoms of B deficiency and toxicity indicate that B has restricted mobility. Nevertheless, B is present in phloem and is retranslocated in phloem, often in sufficient amounts to satisfy the demands of developing sink regions that do not readily transpire. In species that produce significant amounts of

Patrick H. Brown; Barry J. Shelp

1997-01-01

236

Using a basin-scale hydrological model to estimate crop transpiration and soil evaporation  

Microsoft Academic Search

Increasing populations and expectations, declining crop yields and the resulting increased competition for water necesitate improvements in irrigation management and productivity. A key factor in defining agricultural productivity is to be able to simulate soil evaporation and crop transpiration. In agribusiness terms, crop transpiration is a useful process while soil and open-water evaporations are wasteful processes. In this study a

G. Kite

2000-01-01

237

Measuring and modeling the variation in species-specific transpiration in temperate deciduous hardwoods.  

PubMed

We investigated which parameters required by the MAESTRA model were most important in predicting leaf-area-based transpiration in 5-year-old trees of five deciduous hardwood species-yoshino cherry (Prunus x yedoensis Matsum.), red maple (Acer rubrum L. 'Autumn Flame'), trident maple (Acer buergeranum Miq.), Japanese flowering cherry (Prunus serrulata Lindl. 'Kwanzan') and London plane-tree (Platanus x acerifolia (Ait.) Willd.). Transpiration estimated from sap flow measured by the heat balance method in branches and trunks was compared with estimates predicted by the three-dimensional transpiration, photosynthesis and absorbed radiation model, MAESTRA. MAESTRA predicted species-specific transpiration from the interactions of leaf-level physiology and spatially explicit micro-scale weather patterns in a mixed deciduous hardwood plantation on a 15-min time step. The monthly differences between modeled mean daily transpiration estimates and measured mean daily sap flow ranged from a 35% underestimation for Acer buergeranum in June to a 25% overestimation for A. rubrum in July. The sensitivity of the modeled transpiration estimates was examined across a 30% error range for seven physiological input parameters. The minimum value of stomatal conductance as incident solar radiation tends to zero was determined to be eight times more influential than all other physiological model input parameters. This work quantified the major factors that influence modeled species-specific transpiration and confirmed the ability to scale leaf-level physiological attributes to whole-crown transpiration on a species-specific basis. PMID:18765372

Bowden, Joseph D; Bauerle, William L

2008-11-01

238

A backward propagation neural network for predicting daily transpiration of poplar  

Microsoft Academic Search

In this study, a supervised artificial neural network (ANN) trained by back propagation (BP) algorithm s was developed to predict the transpiration of poplar based on six input variables. Based on the transpiration characteristics of trees, a three?layer BP network was constructed with six input units and one output unit. Daily average temperature, relative humidity, photosynthetic affective radiation, wind speed,

Yan Meijun; Yang Peiling; Ren Shumei; Luo Yuanpei; Xu Tingwu

2007-01-01

239

The rates of shoot and root growth in intact plants of pea mutants in leaf morphology  

Microsoft Academic Search

Isogenic lines of pea (Pisum sativum L.) with the genetically determined changes in leaf morphology, afila (af) and tendril-less (tl), were used to study the relationship between shoot and root growth rates. The time-course of shoot and root growth was followed\\u000a during the pre-floral period in the intact plants grown under similar conditions. The af mutation produced afila leaves without

E. M. Kof; I. A. Vinogradova; A. S. Oorzhak; Z. V. Kalibernaya

2006-01-01

240

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

241

Hazard rating of ash and slag dumps of thermal power plants firing Kuznetskii coal  

SciTech Connect

Results of a study of the degree of toxicity and of the hazard rating of ash and slag waste due to firing Kuznetskii coals at thermal power plants are presented. Computation shows and biological tests prove that the waste belongs to the fifth hazard class, i.e., is virtually safe. Comparison of the results obtained with foreign data shows that the waste in question belongs to the safe category in accordance with foreign standards as well.

E.P. Dik; A.N. Soboleva [All-Russia Thermal Engineering Institute (VTI), Moscow (Russian Federation)

2006-03-15

242

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

243

[Soil microbial biomass and respiration rate under effects of different planting patterns of peanut].  

PubMed

A field experiment with randomized design was conducted to study the effects of six planting patterns of peanut, i.e., spring sowing and plastic film mulching, spring sowing and open cultivation, summer sowing and plastic film mulching, summer sowing and open cultivation, intercropped in wheat field, and control of intercropped in wheat field, on soil microbial biomass C, soil active microbial biomass, and soil respiration rate. The results showed that the growth stage and planting pattern of peanut had significant effects on soil microbial biomass and respiration rate. With the prolonged time after anthesis, soil microbial biomass C, active microbial biomass, and respiration rate increased gradually, peaked at pod-setting stage, and decreased then. Open cultivation enhanced soil microbial biomass C and respiration rate but reduced soil active microbial biomass, being unfavorable to soil nutrient transformation and nutrient availability, while plastic film mulching increased soil active microbial biomass, and consequently, promoted soil nutrient transformation and nutrient availability. Comparing with intercropped in wheat field and open cultivation, intercropped in wheat field and plastic film mulching increased soil microbial biomass C, active microbial biomass, and respiration rate, which immobilized more soil nutrients and was not conducive to peanut growth. PMID:21265155

Lin, Ying-jie; Gao, Fang; Zhang, Jia-lei; Zhou, Lu-ying; Zhang, Xin-min; Li, Bao-long; Zhao, Hua-jian; Li, Xiang-dong

2010-09-01

244

Effects of elevated pressure on rate of photosynthesis during plant growth.  

PubMed

The aim of this study is to investigate the effects of an artificially controlled environment, particularly elevated total pressure, on net photosynthesis and respiration during plant growth. Pressure directly affects not only cells and organelles in leaves but also the diffusion coefficients and degrees of solubility of CO2 and O2. In this study, the effects of elevated total pressure on the rates of net photosynthesis and respiration of a model plant, Arabidopsis thaliana, were investigated in a chamber that newly developed in this study to control the total pressure. The results clearly showed that the rate of respiration decreased linearly with increasing total pressure at a high humidity. The rate of respiration decreased linearly with increasing total pressure up to 0.2MPa, and increased with increasing total pressure from 0.3 to 0.5MPa at a low humidity. The rate of net photosynthesis decreased linearly with increasing total pressure under a constant partial pressure of CO2 at 40Pa. On the other hand, the rate of net photosynthesis was clearly increased by up to 1.6-fold with increasing total pressure and partial pressure of CO2. PMID:23994480

Takeishi, Hiroyuki; Hayashi, Jun; Okazawa, Atsushi; Harada, Kazuo; Hirata, Kazumasa; Kobayashi, Akio; Akamatsu, Fumiteru

2013-08-29

245

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.

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

246

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

247

Use of sulfur-34 to measure the absorption rate of sulfur dioxide on the leaves of plants  

Microsoft Academic Search

A new method has been developed for measuring the rate of sulphur ; dioxide absorption by plants. This rate is deduced from the isotopic composition ; of the sulphur contained in plants before and after fumigation with ³⁴S-; enriched sulphur dioxide, the production of which is also described. The ; fumigation, which is carried out in the field with a

Y. Belot; J. C. Bourreau; M. Dubois; C. Pauly

1975-01-01

248

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

249

Effect of NaCl salinity on growth, pigment and mineral element contents, and gas exchange of broad bean and pea plants  

Microsoft Academic Search

Increasing salinity of growth medium induced a reduction in growth and transpiration rate. The concentrations of chlorophylls\\u000a and carotenoids were increased in most cases in broad bean leaves while in pea plants they remained more or less unchanged\\u000a with the rise of salinization up to 80mM NaCl. Thereabove a significant decrease in these contents was observed. A stimulation\\u000a of the

A. M. HAMADA; A. E. El-Enany

1994-01-01

250

Intercellular CO 2 concentration and water-use efficiency of temperate plants with different life-forms and from different microhabitats  

Microsoft Academic Search

Summary Photosynthesis and transpiration were measured simultaneously, under near-optimum and constant environmental conditions, in intact leaves of plants native to the temperate forest region. A linear relationship between photosynthetic rate and stomatal conductance was found in every species tested irrespective of leaf age or season, indicating that the calculated intercellular CO2 concentration and water-use efficiency were fairly constant within a

F. Yoshie

1986-01-01

251

Involvement of root ABA and hydraulic conductivity in the control of water relations in wheat plants exposed to increased evaporative demand  

Microsoft Academic Search

We studied the possible involvement of ABA in the control of water relations under conditions of increased evaporative demand.\\u000a Warming the air by 3°C increased stomatal conductance and raised transpiration rates of hydroponically grown Triticum durum plants while bringing about a temporary loss of relative water content (RWC) and immediate cessation of leaf extension. However,\\u000a both RWC and extension growth

Guzel Kudoyarova; Svetlana Veselova; Wolfram Hartung; Rashit Farhutdinov; Dmitry Veselov; Guzyal Sharipova

2011-01-01

252

Transpiration in a sub-tropical ridge-top cloud forest  

NASA Astrophysics Data System (ADS)

Laurel forests in the Canary Islands (Spain) survive where humid conditions are guaranteed throughout the year. On peaks and ridges, laurel forest gives way to mixed evergreen tree-heath/beech forest of low stature ("fayal-brezal") that has to cope with rapidly changing light, temperature and humidity conditions due to the occurrence of intermittent sunny and foggy periods during the mostly rainless summer. These conditions are poorly understood and there is a lack of information on the interrelations between tree physiological behavior and ambient climatic and soil water conditions in fayal-brezal. In this study sap velocities were measured for 2 years in two dominant tree species (Myrica faya and Erica arborea) in a ridge-top forest in the National Park of Garajonay on the island of La Gomera. The resulted average daily stand transpiration was 1.2 ± 0.12 mm (416 mm year-1). However, the narrow-leaved E. arborea exhibited higher sap velocities than the broad-leaved M. faya. Also, sap velocity increased with stem diameter in E. arborea but not in M. faya. Nocturnal flow activity was observed throughout the year and reflected ambient conditions on some occasions, and stem water storage recovery on others. Strong stomatal control in response to increases in vapor pressure deficit was seen in both species. Fog reduced sap velocity from 10% up to 90% but no consistent pattern was found. Soil water uptake during the dry summer (246 mm) was much larger than atmospheric water inputs (41 mm, rain and fog). The low moisture levels in the top 0.3 m of the soil had limited influence on transpiration rates indicating that vegetation must have had access to moisture in deeper layers.

García-Santos, G.

2012-09-01

253

Life history influences rates of climatic niche evolution in flowering plants  

PubMed Central

Across angiosperms, variable rates of molecular substitution are linked with life-history attributes associated with woody and herbaceous growth forms. As the number of generations per unit time is correlated with molecular substitution rates, it is expected that rates of phenotypic evolution would also be influenced by differences in generation times. Here, we make the first broad-scale comparison of growth-form-dependent rates of niche evolution. We examined the climatic niches of species on large time-calibrated phylogenies of five angiosperm clades and found that woody lineages have accumulated fewer changes per million years in climatic niche space than related herbaceous lineages. Also, climate space explored by woody lineages is consistently smaller than sister lineages composed mainly of herbaceous taxa. This pattern is probably linked to differences in the rate of climatic niche evolution. These results have implications for niche conservatism; in particular, the role of niche conservatism in the distribution of plant biodiversity. The consistent differences in the rate of climatic niche evolution also emphasize the need to incorporate models of phenotypic evolution that allow for rate heterogeneity when examining large datasets.

Smith, Stephen A.; Beaulieu, Jeremy M.

2009-01-01

254

Strobilurin fungicides induce changes in photosynthetic gas exchange that do not improve water use efficiency of plants grown under conditions of water stress.  

PubMed

The effects of five strobilurin (beta-methoxyacrylate) fungicides and one triazole fungicide on the physiological parameters of well-watered or water-stressed wheat (Triticum aestivum L.), barley (Hordeum vulgare L.) and soya (Glycine max Merr.) plants were compared. Water use efficiency (WUE) (the ratio of rate of transpiration, E, to net rate of photosynthesis, A(n)) of well-watered wheat plants was improved slightly by strobilurin fungicides, but was reduced in water-stressed plants, so there is limited scope for using strobilurins to improve the water status of crops grown under conditions of drought. The different strobilurin fungicides had similar effects on plant physiology but differed in persistence and potency. When applied to whole plants using a spray gun, they reduced the conductance of water through the epidermis (stomatal and cuticular transpiration), g(sw), of leaves. Concomitantly, leaves of treated plants had a lower rate of transpiration, E, a lower intercellular carbon dioxide concentration, c(i), and a lower net rate of photosynthesis, A(n), compared with leaves of control plants or plants treated with the triazole. The mechanism for the photosynthetic effects is not known, but it is hypothesised that they are caused either by strobilurin fungicides acting directly on ATP production in guard cell mitochondria or by stomata responding to strobilurin-induced changes in mesophyll photosynthesis. The latter may be important since, for leaves of soya plants, the chlorophyll fluorescence parameter F(v)/F(m) (an indication of the potential quantum efficiency of PSII photochemistry) was reduced by strobilurin fungicides. It is likely that the response of stomata to strobilurin fungicides is complex, and further research is required to elucidate the different biochemical pathways involved. PMID:17912684

Nason, Mark A; Farrar, John; Bartlett, David

2007-12-01

255

Atmospheric Pb and Ti accumulation rates from Sphagnum moss: dependence upon plant productivity.  

PubMed

The accumulation rates of atmospheric Pb and Ti were obtained using the production rates of Sphagnum mosses collected in four ombrotrophic bogs from two regions of southern Germany: Upper Bavaria (Oberbayern, OB) and the Northern Black Forest (Nordschwarzwald, NBF). Surfaces of Sphagnum carpets were marked with plastic mesh and one year later the production of plant matter was harvested. Metal concentrations were determined in acid digests using sector field ICP-MS employing well established analytical procedures. Up to 12 samples (40 x 40 cm) were collected per site, and 6-10 sites were investigated per bog. Variations within a given sampling site were in the range 2.3-4x for Pb concentrations, 1.8-2.5x for Ti concentrations, 3-8.3x for Pb/Ti, 5.6-7.8x for Pb accumulation rates, and 2.3-6.4x for Ti accumulation rates. However, the median values of these parameters for the sites (6-10 per bog) were quite consistent. The mosses from the bogs in NBF exhibited significantly greater productivity (187-202 g m(-2) a(-1)) compared to the OB peat bogs (71-91 g m(-2) a(-1)), and these differences had a pronounced effect on the Pb and Ti accumulation rates. Highly productive mosses showed no indication of a "dilution effect" of Pb or Ti concentrations, suggesting that more productive plants were simply able to accumulate more particles from the air. The median rates of net Pb accumulation by the mosses are in excellent agreement with the fluxes obtained by direct atmospheric measurements at nearby monitoring stations in both regions (EMEP and MAPESI data). PMID:20545344

Kempter, H; Krachler, M; Shotyk, W

2010-07-15

256

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

257

Desert Emergency - Lack of Water - How to Find and Collect Water. Plants and Human Survival in the Desert.  

National Technical Information Service (NTIS)

This study concentrated on the plant and environmental factors which influence the yield of water transpiration which can be collected from 2 widespread plant species, Retama raetam and Phragmites australis; the latter plant gives a much higher yield. Thi...

Y. Gutterman

1985-01-01

258

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

259

Effects of Post-fire Succession and Edaphic Conditions on Tree Transpiration in a Boreal Black Spruce Forest  

NASA Astrophysics Data System (ADS)

Boreal forest ecosystems play an integral role in global climate change because of their large land area and ability to store large quantities of carbon. Quantifying and explaining tree water use in both well- and poorly- drained soils and across successional development is critical in understanding the influence of physiological processes on carbon, water, and energy cycling. Four black spruce stands burned in 1850, 1930, 1964, and 1989 were chosen for this research because they had been shown in previous studies to represent critical stages of forest development that capture the successional impacts of both leaf area and species composition change. We hypothesized that tree transpiration will differ between well- and poorly-drained areas and with age due to 1) tree size and age and edaphic-related hydraulic adjustments and 2) tree size will be explained by species specific growth differences from edaphic conditions. Sap flux, leaf water potential (\\PsiL), site specific allometric relationships between sapwood area and leaf area and soil properties such as texture and organic matter depth in each of the four burn ages were utilized to test these hypotheses. Results show that sap flux for Picea mariana at the 1964 burn age differed between well- and poorly-drained soils when scaled per unit xylem area with trees located on poorly-drained soils experiencing higher sap flux rates than trees in well- drained areas (101.79 & 83.02 g cm-2 day-1 respectively). However, when scaled to transpiration on a per tree basis, taking tree size into account, trees on well-drained soils had higher rates than those in poorly- drained locations (366.96 & 216.82 g tree-1 day-1 respectively). The presence of Pinus banksiana and Populus tremuloides in the well-drained areas increased stand transpiration rates for these areas considerably as compared to the poorly-drained areas. Midday \\PsiL for all four burns show no significant difference between well- and poorly-drained (average midday \\PsiL = -1.23 & -1.29 MPa respectively) sites for Picea mariana (t-value = -0.591, df = 6, p-value = 0.576). This indicates that tree size, which is constrained by growth and anaerobic conditions, drives differences in tree transpiration for well- and poorly-drained soils.

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

2007-12-01

260

A prototype photovoltaic/thermal system integrated with transpired collector  

SciTech Connect

Building-integrated photovoltaic/thermal (BIPV/T) systems may be utilized to produce useful heat while simultaneously generating electricity from the same building envelope surface. A well known highly efficient collector is the open-loop unglazed transpired collector (UTC) which consists of dark porous cladding through which outdoor air is drawn and heated by absorbed solar radiation. Commercially available photovoltaic systems typically produce electricity with efficiencies up to about 18%. Thus, it is beneficial to obtain much of the normally wasted heat from the systems, possibly by combining UTC with photovoltaics. Combination of BIPV/T and UTC systems for building facades is considered in this paper - specifically, the design of a prototype facade-integrated photovoltaic/thermal system with transpired collector (BIPV/T). A full scale prototype is constructed with 70% of UTC area covered with PV modules specially designed to enhance heat recovery and compared to a UTC of the same area under outdoor sunny conditions with low wind. The orientation of the corrugations in the UTC is horizontal and the black-framed modules are attached so as to facilitate flow into the UTC plenum. While the overall combined thermal efficiency of the UTC is higher than that of the BIPV/T system, the value of the generated energy - assuming that electricity is at least four times more valuable than heat - is between 7% and 17% higher. Also, the electricity is always useful while the heat is usually utilized only in the heating season. The BIPV/T concept is applied to a full scale office building demonstration project in Montreal, Canada. The ratio of photovoltaic area coverage of the UTC may be selected based on the fresh air heating needs of the building, the value of the electricity generated and the available building surfaces. (author)

Athienitis, Andreas K.; Bambara, James; O'Neill, Brendan; Faille, Jonathan [Dept. of Building, Civil and Environmental Engineering, Concordia University, 1455 Maisonneuve W., Montreal, Quebec (Canada)

2011-01-15

261

The allometry of plant spacing that regulates food intake rate in mammalian herbivores.  

PubMed

The distance that mammalian herbivores can travel without interrupting food processing corresponds to a distance threshold (d*) in plant spacing where change occurs in the mechanisms regulating the functional response. The instantaneous rate of food consumption is controlled by food encounter rate when plant spacing exceeds d*. Below this threshold, food processing in the mouth controls instantaneous intake rate. The distance threshold provides a mechanistic definition of the scale of heterogeneity of the food resource. Recent work indicates that d* should scale positively with the body mass of mammalian herbivores. Here I evaluated the empirical evidence for this positive scaling by investigating (1) herbivores consuming only alfalfa (Medicago sativa), (2) grazers, and (3) herbivores consuming any kind of vegetation. Overall, I found greater evidence for a negative than for a positive scaling of d*. Out of the three groups, only herbivores consuming alfalfa could yield a positive covariation between d* and body mass. However, even this positive scaling became negative when herbivores consumed bites of alfalfa that were only a fraction of their maximum size. Finally, d* also scaled negatively among herbivores foraging in similar food patches. Overall, differences in foraging decisions among mammalian herbivores seem more likely to have been shaped by a negative than a positive scaling of d*. PMID:16922334

Fortin, Daniel

2006-07-01

262

Importance of precipitation partitioning into vaporization and deep percolation in estimation of evaporation and transpiration  

NASA Astrophysics Data System (ADS)

Evaporation and Transpiration are two important fluxes in the hydrological cycle. Different approaches exist to estimate it as a function of land cover/land use, soil moisture content and atmospheric forcing. We here compare two approaches: ETLook wherein evaporation and transpiration is controlled by AMSRE derived soil moisture induced stress and a Simple Evaporation Transpiration Scheme (SETS) that has similar evaporation and transpiration formulation as ETLook without AMSRE derived soil moisture control but with explicit subsurface soil moisture accounting (and including thus derived soil moisture induced stress). The central question addressed here is whether satellite observation based soil moisture provides a credible control on evaporation and transpiration when explicit subsurface soil moisture accounting, which governs partitioning of precipitation into vaporization and percolation, is absent. We apply the two schemes at daily time scale for the year 2007 for Indus River Basin in Pakistan and India at 1km x 1km spatial resolution. SETS is forced by TRMM precipitation data series and has simpler representation of irrigation. All other data sets and parameter values are same between the two methods. Results show that SETS has a tendency to underpredict ETLook in both evaporation and transpiration. Since evaporation and transpiration schemes are same in both, the differences between the two can only be due to use of TRMM data sets, poorer representation irrigation or explicit representation of subsurface hydrology in SETS. In this study we suggest that explicit subsurface soil moisture accounting plays a major role in explaining the difference between the two.

Ghazanfari, S.; Pande, S.; Cheema, M.; Bastiaanssen, W.; Savenije, H.

2011-12-01

263

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

264

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

2009-06-26

265

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

2009-01-20

266

Spatial distribution of leaf nitrogen and photosynthetic capacity within the foliage of individual trees: disentangling the effects of local light quality, leaf irradiance, and transpiration  

Microsoft Academic Search

There is presently no consensus about the factor(s) driving photosynthetic acclimation and the intra-can- opy distribution of leaf characteristics under natural conditions. The impact was tested of local (i) light quality (red\\/far red ratio), (ii) leaf irradiance (PPFDi), and (iii) transpiration rate (E) on total non-structural carbohydrates per leaf area (TNCa), TNC-free leaf mass-to-area ratio (LMA), total leaf nitrogen per

Ela Frak; Peter Millard; Boris Adam; Erwin Dreyer; Cynthia Escuit; Marc Vandame; Claude Varlet-Grancher

2002-01-01

267

Yield and gas exchange ability of sweetpotato plants cultured in a hydroponic system  

NASA Astrophysics Data System (ADS)

Life support of crews in space is greatly dependent on the amounts of food atmospheric O 2 and clean water produced by plants Therefore the space farming systems with scheduling of crop production obtaining high yields with a rapid turnover rate converting atmospheric CO 2 to O 2 and purifying water should be established with employing suitable plant species and varieties and precisely controlling environmental variables around plants grown at a high density in a limited space In this study three sweetpotato varieties were cultured in a newly developed hydroponic system and the yield the photosynthetic rate and the transpiration rate were compared on the earth as a fundamental study for establishing the space farming systems The varieties were Elegant summer Koukei 14 and Beniazuma The hydroponic system mainly consisted of water channels and rockwool boards A growing space for roots was made between the rockwool board and nutrient solution in the water channel Storage roots were developed on the lower surface of the rockwool plates Fresh weights of the storage roots were 1 6 1 2 and 0 6 kg plant for Koukei 14 Elegant summer and Beniazuma respectively grown for five months from June to October under the sun light in Osaka Japan Koukei 14 and Elegant summer produced greater total phytomass than Beniazuma There were positive correlations among the total phytomass the net photosynthetic rate and the transpiration rate Young stems and leaves as well as storage roots of Elegant summer are edible Therefore Elegant-summer

Kitaya, Y.; Hirai, H.; Saiful Islam, A. F. M.; Yamamoto, M.

268

Thermal transpiration of a slightly rarefied gas through a horizontal straight pipe in the presence of weak gravitation  

NASA Astrophysics Data System (ADS)

Thermal transpiration of a slightly rarefied gas through a horizontal straight pipe in the presence of weak gravitation is studied on the basis of kinetic theory. We consider the situation in which the Knudsen number (the mean free path divided by the characteristic length of the cross section) is small and the dimensionless gravity (the characteristic length divided by the ascent height of the molecules against gravity) is of the order of the square of the Knudsen number. The behavior of the gas is studied analytically on the basis of the fluid-dynamic-type equation and the slip-type boundary condition derived from the Boltzmann equation for small Knudsen numbers. Extending the analysis of the two-dimensional channel problem, the solution for a pipe with an arbitrary cross section is obtained in a semianalytical form. When the temperature gradient is imposed along the pipe, the pressure gradient is produced not only in the vertical direction but also in the horizontal direction due to the effect of gravity. Although this pressure gradient is of the order of the square of the Knudsen number, it induces a flow of the order of the Knudsen number. As a result, the apparently higher order effect of gravity produces a relatively finite effect on thermal transpiration. This phenomenon, first observed in plane thermal transpiration, is clarified for a pipe with a general cross section. The explicit solution is obtained for the pipe with the cross section of an annulus between eccentric circular cylinders. Based on the solution, the effect of weak gravitation on the mass flow rate of the gas, as well as on the flow velocity, is clarified over a wide range of the radii ratio and the eccentricity of the cylinders.

Doi, Toshiyuki

2013-10-01

269

In low transpiring conditions, nitrate and water fluxes for growth of B. napus plantlets correlate with changes in BnNrt2.1 and BnNrt1.1 nitrate transporter expression  

PubMed Central

We analyzed how changes in BnNrt nitrate transporter gene expression induced by nitrate are associated with morphological changes in plantlets and osmotic water flow for growth. We hypothesized that in a Petri dish system, reduction in transpiration should induce conditions where nitrate and water fluxes for growth depend directly on nitrate transporter activity and nitrate signaling. Rape seedlings growing on agar plates were supplied with increasing external K15NO3 concentrations from 0.05 to 20 mM. After 5 d of treatment, morphological switches in plantlet growth were observed between 0.5 and 5 mM nitrate supply. Root elongation was reduced by 50% while the cotyledon surface area was doubled. These morphological switches were strongly associated with increases in 15NO3- and water uptake rates as well as 15N and water allocation to the shoot. These switches were also highly correlated with the upregulation of BnNrt1.1 and BnNrt2.1 in the root. However, while root expression of BnNrt2.1 was correlated linearly with a shoot growth-associated increase in 15N and water uptake, BnNrt1.1 expression was correlated exponentially with both 15N and water accumulation. In low transpiring conditions, the tight control exercised by nitrate transporters on K15NO3 uptake and allocation clearly demonstrates that they modulated the nitrate-signaling cascade involved in cell growth and as a consequence, water uptake and allocation to the growing organs. Deciphering this signaling cascade in relation to acid growth theory seems to be the most important challenge for our understanding of the nitrate-signaling role in plant growth.

Le Ny, Fabien; Leblanc, Antonin; Beauclair, Patrick; Deleu, Carole; Le Deunff, Erwan

2013-01-01

270

A Plant Notices Insect Egg Deposition and Changes Its Rate of Photosynthesis1  

PubMed Central

Scots pine (Pinus sylvestris) is known to change its terpenoid metabolism in response to egg deposition by the sawfly Diprion pini (Hymenoptera, Diprionidae). Three days after egg deposition, parts of the pine twig adjacent to the egg-laden one are induced to emit volatiles, which attract egg parasitoids. In this study, we investigated whether egg deposition by this sawfly affects pine photosynthesis. Measurements of photosynthesis were taken from untreated control twigs and from pine twigs adjacent to egg-laden ones (i.e. systemically oviposition-induced twigs) for a period of 3 d starting after egg deposition. The net photosynthetic rate of oviposition-induced pine twigs was lower than that of untreated control twigs, whereas the respiration rate of pine twigs was not affected by egg deposition. CO2 response curves of oviposition-induced twigs tended to be lower than those of controls. The potential rate of electron transport (Jmax) and the maximum rate of Rubisco activity (Vcmax) were calculated from the data of the CO2 response curves. Jmax of oviposition-induced twigs was significantly lower than that of controls at day 1 after egg deposition, while the difference diminished from day 2 to day 3. A similar pattern was observed for Vcmax. Light response curves of oviposition-induced twigs were significantly lower than those of untreated ones during 3 d of measurements. Stomatal conductance was slightly lowered by egg deposition. When considering photosynthetic activity as a physiological currency to measure costs of induction of plant defense, the effects of insect egg deposition on gas exchange of pine are discussed with respect to known effects of insect feeding on the photosynthesis activity of plants.

Schroder, Roland; Forstreuter, Manfred; Hilker, Monika

2005-01-01

271

A plant notices insect egg deposition and changes its rate of photosynthesis.  

PubMed

Scots pine (Pinus sylvestris) is known to change its terpenoid metabolism in response to egg deposition by the sawfly Diprion pini (Hymenoptera, Diprionidae). Three days after egg deposition, parts of the pine twig adjacent to the egg-laden one are induced to emit volatiles, which attract egg parasitoids. In this study, we investigated whether egg deposition by this sawfly affects pine photosynthesis. Measurements of photosynthesis were taken from untreated control twigs and from pine twigs adjacent to egg-laden ones (i.e. systemically oviposition-induced twigs) for a period of 3 d starting after egg deposition. The net photosynthetic rate of oviposition-induced pine twigs was lower than that of untreated control twigs, whereas the respiration rate of pine twigs was not affected by egg deposition. CO2 response curves of oviposition-induced twigs tended to be lower than those of controls. The potential rate of electron transport (J(max)) and the maximum rate of Rubisco activity (V(cmax)) were calculated from the data of the CO2 response curves. J(max) of oviposition-induced twigs was significantly lower than that of controls at day 1 after egg deposition, while the difference diminished from day 2 to day 3. A similar pattern was observed for V(cmax). Light response curves of oviposition-induced twigs were significantly lower than those of untreated ones during 3 d of measurements. Stomatal conductance was slightly lowered by egg deposition. When considering photosynthetic activity as a physiological currency to measure costs of induction of plant defense, the effects of insect egg deposition on gas exchange of pine are discussed with respect to known effects of insect feeding on the photosynthesis activity of plants. PMID:15821143

Schröder, Roland; Forstreuter, Manfred; Hilker, Monika

2005-04-08

272

Risk-taking plants: anisohydric behavior as a stress-resistance trait.  

PubMed

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

2012-07-01

273

ZPMHD-a Rep-rated Z-Pinch Power Plant Direct Conversion Concept*  

NASA Astrophysics Data System (ADS)

We have performed a preliminary conceptual study of ZPMHD, a z-pinch driven IFE power plant with Compact Fusion Advanced Rankine (CFARII) MHD direct conversion [B. G. Logan, Fusion Eng. and Des. 22, 151 (1993)]. We find that a competitive power plant could be built that has a Cost of Electricity (CoE) Å 40 mills/kWh for a compact blanket of Lithium Hydride and a fusion yield of 1.6 GJ. This result is based on an assumed target-driver figure of merit, RTD = Fusion gain/Driver unit cost = 4 Yield (J)/Driver cost ($). This figure of merit results from an estimated rep-rated driver unit cost of 20 /J and a target gain G = 80. Advanced targets with higher gain and/or lower driver cost give competitive power plants at higher yields (CoE Å 40 mills/kWh for RTD= 15). We also find that a much higher target-driver figure of merit ( ~ 20 J/) is required for low electricity cost (44 mills/kWh) with a Flibe blanket. *Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed-Martin Company, for the United States Department of Energy Under Contract DE-AC04-94AL85000.

de Groot, John S.; Houssein Alki, El

2001-10-01

274

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

275

Testing the growth rate hypothesis in vascular plants with above- and below-ground biomass.  

PubMed

The growth rate hypothesis (GRH) proposes that higher growth rate (the rate of change in biomass per unit biomass, ?) is associated with higher P concentration and lower C:P and N:P ratios. However, the applicability of the GRH to vascular plants is not well-studied and few studies have been done on belowground biomass. Here we showed that, for aboveground, belowground and total biomass of three study species, ? was positively correlated with N:C under N limitation and positively correlated with P:C under P limitation. However, the N:P ratio was a unimodal function of ?, increasing for small values of ?, reaching a maximum, and then decreasing. The range of variations in ? was positively correlated with variation in C:N:P stoichiometry. Furthermore, ? and C:N:P ranges for aboveground biomass were negatively correlated with those for belowground. Our results confirm the well-known association of growth rate with tissue concentration of the limiting nutrient and provide empirical support for recent theoretical formulations. PMID:22427823

Yu, Qiang; Wu, Honghui; He, Nianpeng; Lü, Xiaotao; Wang, Zhiping; Elser, James J; Wu, Jianguo; Han, Xingguo

2012-03-13

276

Effects of drip irrigation configuration and rate on yield and fruit quality of young highbush blueberry plants  

Technology Transfer Automated Retrieval System (TEKTRAN)

A 4-year study was conducted to determine the effects of drip configuration and irrigation rate on yield and fruit quality in a new planting of highbush blueberry in British Columbia, Canada. Plants were grown in a silt loam soil on raised beds and were non-irrigated or irrigated using one line of d...

277

The influence of temperature, photoperiod and plant type on the predation rate of Macrolophus pygmaeus on Myzus persicae  

Microsoft Academic Search

The effect of temperature and photoperiod on the rate of predation of nymphs and adults of the predator Macrolophus pygmaeus was studied using Myzus persicae prey feeding on egg-plant and pepper plants. The experiments were conducted at three photoperiods (16L:8D, 12L:12D and 8L:16D), three temperatures (20, 25 and 30 °C), and at 65% r.h. The rate of predation increased with

D. C. H. Perdikis; D. P. Lykouressis; L. P. Economou

1999-01-01

278

Leaf Energy Balance and Transpirational Relationships of Tulip Poplar (Liriodendron tulipifera).  

National Technical Information Service (NTIS)

Relationships between several physiological parameters of in situ tulip poplar (Liriodendron tulipifera L.) foliage, and its surrounding forest environment were examined, with emphasis on the transpirational process. Objectives were to measure and compare...

R. K. McConathy S. B. McLaughlin D. E. Reichle B. E. Dinger

1976-01-01

279

Experimental Studies of Transpiration Cooling with Shock Interaction in Hypersonic Flow, Part B.  

National Technical Information Service (NTIS)

This report describes the result of experimental studies conducted to examine the effects of the impingement of an oblique shock on the flowfield and surface characteristics of a transpiration-cooled wall in turbulent hypersonic flow. The principal object...

M. S. Holden

1994-01-01

280

Stomatal Conductance and Transpirational Responses of Field-Grown Cotton to Ozone.  

National Technical Information Service (NTIS)

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 gr...

P. J. Temple

1986-01-01

281

Evaluation of Crop Transpiration with Remote Sensing and Computer Simulation Models.  

National Technical Information Service (NTIS)

A Geo Information System (GIS) in which remotely sensed imagery is used to extrapolate and verify agrohydrological model simulations is developed. A one dimensional model is applied to simulated crop transpiration for different soil types. Simulation maps...

J. W. Miltenburg W. Beekman

1989-01-01

282

The ?-Subunit of the Arabidopsis Heterotrimeric G Protein, GPA1, Is a Regulator of Transpiration Efficiency1[C][W][OA  

PubMed Central

Land plants must balance CO2 assimilation with transpiration in order to minimize drought stress and maximize their reproductive success. The ratio of assimilation to transpiration is called transpiration efficiency (TE). TE is under genetic control, although only one specific gene, ERECTA, has been shown to regulate TE. We have found that the ?-subunit of the heterotrimeric G protein in Arabidopsis (Arabidopsis thaliana), GPA1, is a regulator of TE. gpa1 mutants, despite having guard cells that are hyposensitive to abscisic acid-induced inhibition of stomatal opening, have increased TE under ample water and drought stress conditions and when treated with exogenous abscisic acid. Leaf-level gas-exchange analysis shows that gpa1 mutants have wild-type assimilation versus internal CO2 concentration responses but exhibit reduced stomatal conductance compared with ecotype Columbia at ambient and below-ambient internal CO2 concentrations. The increased TE and reduced whole leaf stomatal conductance of gpa1 can be primarily attributed to stomatal density, which is reduced in gpa1 mutants. GPA1 regulates stomatal density via the control of epidermal cell size and stomata formation. GPA1 promoter::?-glucuronidase lines indicate that the GPA1 promoter is active in the stomatal cell lineage, further supporting a function for GPA1 in stomatal development in true leaves.

Nilson, Sarah E.; Assmann, Sarah M.

2010-01-01

283

Transpirational water use and its regulation in the mountainous terrain of S. Korea  

NASA Astrophysics Data System (ADS)

Quantifying water use by forests growing on complex mountainous terrain is difficult and understanding of controls on water use by these forests a challenge. Yet mountains are crucial as water towers and better understanding of their hydrology and ecology is critical for sustainable management. Consequently, there is a growing need for new research approaches designed with attention to the particular needs and constraints of large-scale studies and that have the potential to generate reliable and accurate data. The use of a combination of different sapflow-measurement techniques provides a unique opportunity to monitor water use by the understory and canopy forest tree species at micro-scale, allowing for accurate estimation of total forest water use. The obtained data, in conjunction with intensively measured climatic variables, allow for better understanding and interpretation of transpiration results. A research initiative under the International Training Group: Complex Terrain and Ecological Heterogeneity (TERRECO) seeks to address pertinent issues related to forest water use and production in complex terrain. Stem Heat balance (SHB) and Heat Dissipation techniques have been employed to measure sapflow in the understory woody plants and tree branches and on stems of canopy trees respectively. Measurements have been stratified to account for differences in tree sizes and species diversity. To better understand the data, we are intensively monitoring soil moisture at 5, 10 and 30 cm depths, in addition to a range of micrometeorology sensors that have been set up below, within and above the canopy. These measurements have been planned, taking into account altitudinal/elevation gradient, aspect and within site differences in species composition and tree sizes and to generate data for large-scale modeling of the entire catchment. A total of 70 trees from 9 species growing in six different locations at varying elevations and aspects are being monitored. Peak daily water use by trees during mid summer amounts to 45 kg d-1 but varies significantly with sapwood area. Within a species, there is a consistent relationship between tree size (DBH) and sapwood area irrespective of elevation. We have also established a common trend in the relationship between wood density and sap flux density (Js) that transcends the boundaries of species differences. These initial findings are critical for our planned upscaling of water use by the forest catchment. In addition to soil moisture, vapor pressure deficit (VPD) and light play a crucial regulatory role on forest water use. We are at the stage of establishing a common link that brings together micrometeorology and transpiration that will allow for large scale modeling of forest water use.

Otieno Dennis, O.; Eunyoung, J.; Sinkyu, K.; Tenhunen, J. D.

2009-12-01

284

MRI links stem water content to stem diameter variations in transpiring trees.  

PubMed

In trees, stem diameter variations are related to changes in stem water content, because internally stored water is depleted and replenished over a day. To confirm this relationship, non-invasive magnetic resonance imaging (MRI) was combined with point dendrometer measurements in three actively transpiring oak (Quercus robur L.) trees. Two of these oak trees were girdled to study the stem increment above the girdling zone. MRI images and micrographs of stem cross-sections revealed a close link between the water distribution and the anatomical features of the stem. Stem tissues with the highest amount of water were physiologically the most active ones, being the youngest differentiating xylem cells, the cambium and the youngest differentiating and conductive phloem cells. Daily changes in stem diameter corresponded well with the simultaneously MRI-measured amount of water, confirming their strong interdependence. MRI images also revealed that the amount of water in the elastic bark tissues, excluding cambium and the youngest phloem, contributed most to the daily stem diameter changes. After bark removal, an additional increase in stem diameter was measured above the girdle. This increase was attributed not only to the cambial production of new cells, but also to swelling of existing bark cells. In conclusion, the comparison of MRI and dendrometer measurements confirmed previous interpretations and applications of dendrometers and illustrates the additional and complementary information MRI can reveal regarding water relations in plants. PMID:22268159

De Schepper, Veerle; van Dusschoten, Dagmar; Copini, Paul; Jahnke, Siegfried; Steppe, Kathy

2012-01-20

285

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

2010-04-03

286

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

287

Transpiration of a 64-year-old maritime pine stand in Portugal  

Microsoft Academic Search

The transpiration, sap flow, stomatal conductance and water relations ofPinus pinaster were determined during spring and summer in a 64-year-old stand in Ribatejo (Portugal). The transpiration of the pine canopy was determined from sap flow or eddy covariance techniques. Canopy conductance values (gc) were estimated from inversion methods using eddy covariance or sap flow data, respectively, and from scaling-up methods

D. Loustau; P. Berbigier; P. Roumagnac; C. Arruda-Pacheco; J. S. David; M. I. Ferreira; J. S. Pereira; R. Tavares

1996-01-01

288

Transpiration of a hybrid poplar plantation in Saxony (Germany) in response to climate and soil conditions  

Microsoft Academic Search

The aim of this study was to investigate transpiration and its main driving factors on the example of a hybrid poplar plantation\\u000a with the clone Populus maximowiczii × P. nigra, cv. Max 1 on a site in the hilly loess region of Saxony (Germany). Transpiration was measured using sap flow techniques\\u000a during the 2007 and 2008 growing season. At the

Rainer PetzoldKai; Kai Schwärzel; Karl-Heinz Feger

289

SCWO of salt containing artificial wastewater using a transpiring-wall reactor: Experimental results  

Microsoft Academic Search

Experimental results using a transpiring-wall reactor (TWR) for supercritical water oxidation (SCWO) containing a hydrothermal flame as an internal heat source are presented. Our reactor set-up is aimed at overcoming the problem of reactor fouling and plugging due to precipitation of salts. Two types of transpiring-wall elements with different porosity were investigated. Experiments with artificial wastewater containing methanol and sodium

K. Príkopský; B. Wellig; Ph. Rudolf von Rohr

2007-01-01

290

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.

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

2010-01-01

291

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

2010-05-05

292

Dynamic evolution of plant mitochondrial genomes: Mobile genes and introns and highly variable mutation rates  

PubMed Central

We summarize our recent studies showing that angiosperm mitochondrial (mt) genomes have experienced remarkably high rates of gene loss and concomitant transfer to the nucleus and of intron acquisition by horizontal transfer. Moreover, we find substantial lineage-specific variation in rates of these structural mutations and also point mutations. These findings mostly arise from a Southern blot survey of gene and intron distribution in 281 diverse angiosperms. These blots reveal numerous losses of mt ribosomal protein genes but, with one exception, only rare loss of respiratory genes. Some lineages of angiosperms have kept all of their mt ribosomal protein genes whereas others have lost most of them. These many losses appear to reflect remarkably high (and variable) rates of functional transfer of mt ribosomal protein genes to the nucleus in angiosperms. The recent transfer of cox2 to the nucleus in legumes provides both an example of interorganellar gene transfer in action and a starting point for discussion of the roles of mechanistic and selective forces in determining the distribution of genetic labor between organellar and nuclear genomes. Plant mt genomes also acquire sequences by horizontal transfer. A striking example of this is a homing group I intron in the mt cox1 gene. This extraordinarily invasive mobile element has probably been acquired over 1,000 times separately during angiosperm evolution via a recent wave of cross-species horizontal transfers. Finally, whereas all previously examined angiosperm mtDNAs have low rates of synonymous substitutions, mtDNAs of two distantly related angiosperms have highly accelerated substitution rates.

Palmer, Jeffrey D.; Adams, Keith L.; Cho, Yangrae; Parkinson, Christopher L.; Qiu, Yin-Long; Song, Keming

2000-01-01

293

Effect of salinity on water relations of wild barley plants differing in salt tolerance  

PubMed Central

Background and aims Certain lines of wild barley (Hordeum spontaneum) are more tolerant of salinity than others. The physiological basis of this difference is examined in a comparative study of a saline-tolerant and saline-intolerant line that emphasizes plant water relations. Methodology Effects of salt-treatment (75 mM maximum) extending from a few hours to 3 weeks were quantified in 8-day-old seedlings of a saline-sensitive wild barley line (‘T-1’) and a less saline-sensitive line (‘20-45’). Plants were grown in nutrient culture. Levels of mRNA of the HtPIP2;4 aquaporin (AQP) gene were determined together with a range of physiological responses including root hydraulic conductivity, osmotic potential of root xylem sap, transpiration, leaf relative water content, root water content, leaf water potential, leaf sap osmolality, leaf length, leaf area and chlorophyll content. Principal results Salt treatment inhibited transpiration and hydraulic conductivity more in salt-tolerant ‘20-45’ plants than in salt-sensitive ‘T-1’. In ‘20-45’, the effect was paralleled by a fast (within a few hours) and persistent (3 days) down-regulation of aquaporin. In salt-sensitive ‘T-1’ plants, aquaporin down-regulation was delayed for up to 24 h. Greater tolerance in ‘20-45’ plants was characterized by less inhibition of leaf area, root fresh weight, leaf water content and chlorophyll concentration. Leaf water potentials were similar in both lines. Conclusions (i) Decline in hydraulic conductivity in salt-treated barley plants is important for stomatal closure, (ii) lowered transpiration rate is beneficial for salt tolerance, at least at the seedling stage and (iii) changes in AQP expression are implicated in the control of whole plant hydraulic conductivity and the regulation of shoot water relations.

Vysotskaya, Lidia; Hedley, Peter E.; Sharipova, Guzel; Veselov, Dmitry; Kudoyarova, Guzel; Morris, Jennifer; Jones, Hamlyn G.

2010-01-01

294

Increase in recombination rate in Arabidopsis thaliana plants sharing gaseous environment with X-ray and UVC-irradiated plants depends on production of radicals  

PubMed Central

X-ray and UVC are the two physical agents that damage DNA directly, with both agents capable of inducing double-strand breaks. Some of our recent work has demonstrated that local exposure to UVC results in a systemic increase in recombination frequency, suggesting that information about exposure can be passed from damaged to non-damaged tissue. Indeed, we recently showed that plants sharing the same enclosed environment with UVC-irradiated plants exhibit similar increase in homologous recombination frequency as irradiated plants. Here, we further tested whether yet another DNA-damaging agent, X-ray, is capable of increasing recombination rate (RR) in neighboring plants grown in a Petri dish. To test this, we grew plants exposed to X-ray or UVC irradiation in an enclosed environment next to non-exposed plants. We found that both X-ray and UVC-irradiated plants and neighboring plants exhibited comparable increases in the levels of strand breaks and the RR. We further showed that pre-exposure of plants to radical scavenger DMSO substantially alleviates the radiation-induced increase in RR and prevents formation of bystander signal. Our results suggest that the increase in RR in bystander plants can also be triggered by X-ray and that radicals may play some role in initiation or maintenance of this signal.

Zemp, Franz J.; Sidler, Corinne; Kovalchuk, Igor

2012-01-01

295

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

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 (NREL) has actively studied this technology and monitored performance at several installations. A calibrated model that uses typical meteorological weather data to determine absorber plate efficiency resulted from this work. With this model, an economic analysis across heating climates was done to show the effects of collector size, tilt, azimuth, and absorptivity. The analysis relates the internal rate of return of a system based on the cost of the installed absorber area. In general, colder and higher latitude climates return a higher rate of return because the heating season extends into months with good solar resource. Wal-Mart has installed approximately 8,000 ft{sup 2} of absorber at its experimental store in Aurora, Colorado. The delivered energy efficiency was measured at 8-11% during January and February 2007. The low collection efficiency is largely due to the oversized absorber and to the multizone control strategy that limits the amount of air pulled through the collector. Analysis shows that more than 50% of the incident solar energy could be delivered with proper control strategy changes.

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

2008-01-01

296

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

297

Rates of evolution in seed plants: Net increase in diversity of chromosome numbers and species numbers through time  

PubMed Central

An approach was made to the problem of estimating rates of chromosomal evolution in plants. This was done by considering variability in chromosome number within genera whose ages are known approximately from fossil and biogeographic evidence. The relative increases in chromosome number diversity per lineage per unit time were as follows: herbaceous angiosperms, 100; woody angiosperms, 14; conifers, 2; and cycads, 0. Rates of increase in species diversity were estimated in an analogous way. These rates were strongly correlated with the karyotypic rates. These evolutionary rate differences between major groups of seed plants are largely explicable in terms of the breeding structures of populations. Herbs usually have small to moderate effective population sizes, and relatively high dispersability. By contrast, woody angiosperms and gymnosperms are usually obligate outbreeders with large effective population sizes and low dispersability. Thus the probability of fixing and dispersing new karyotypes or novel character ensembles is higher in herbs than in other seed plants.

Levin, D. A.; Wilson, A. C.

1976-01-01

298

Temperature and transpiration resistances of xanthium leaves as affected by air temperature, humidity, and wind speed.  

PubMed

Transpiration and temperatures of single, attached leaves of Xanthium strumarium L. were measured in high intensity white light (1.2 calories per square centimeter per minute on a surface normal to the radiation), with abundant water supply, at wind speeds of 90, 225, and 450 centimeters per second, and during exposure to moist and dry air. Partitioning of absorbed radiation between transpiration and convection was determined, and transpiration resistances were computed.Leaf resistances decreased with increasing temperature (down to a minimum of 0.36 seconds per centimeter). Silicone rubber replicas of leaf surfaces proved that the decrease was due to increased stomatal apertures. At constant air temperature, leaf resistances were higher in dry than in moist air with the result that transpiration varied less than would have been predicted on the basis of the water-vapor pressure difference between leaf and air.The dependence of stomatal conductance on temperature and moisture content of the air caused the following effects. At air temperatures below 35 C, average leaf temperatures were above air temperature by an amount dependent on wind velocity; increasing wind diminished transpiration. At air temperatures above 35 C, leaf temperatures were below air temperatures, and increasing wind markedly increased transpiration. Leaf temperatures equaled air temperature near 35 C at all wind speeds and in moist as well as in dry air. PMID:16657458

Drake, B G; Raschke, K; Salisbury, F B

1970-08-01

299

Effects of Bois noir on carbon assimilation, transpiration, stomatal conductance of leaves and yield of grapevine (Vitis vinifera) cv. Chardonnay.  

PubMed

Bois noir (BN) is one of the main phytoplasma diseases of grapevine (Vitis vinifera). It is widespread, and can cause severe losses in European vineyards. The infective agent colonizes phloem elements and induces visible symptoms of leaf yellowing or reddening after a relatively long incubation period. As the most sensitive cultivars to BN, Chardonnay plants were grouped as healthy or symptomatic in spring, based on the records from the previous year. Leaf gas exchange and chlorophyll a fluorescence were measured weekly from July to September in healthy plants, and in symptomatic and asymptomatic leaves from symptomatic plants. The midday relative water content (mRWC) was measured once per month. The detection of phytoplasma DNA by nested-polymerase chain reaction revealed BN infection in symptomatic leaf samples at the end of September. A significant decrease in pigment content and maximum quantum efficiency of photosystem II (Fv/Fm) of these symptomatic leaves was detected from July to September, although in the asymptomatic leaves of the symptomatic plants the net photosynthesis (Pn) decrease was not significant. In the leaves from the healthy plants, Pn and transpiration were relatively stable. Of note, in July, an initially healthy plant showed a strong Pn reduction that was followed by visible leaf yellowing symptoms only in August. The phytoplasma infection also stimulated significant reductions in mRWC of the symptomatic leaves, with a final large decrease in yield. PMID:22715513

Endeshaw, Solomon T; Murolo, Sergio; Romanazz, Gianfranco; Neri, Davide

2012-06-01

300

Short-term and long-term effects of low total pressure on gas exchange rates of spinach  

NASA Astrophysics Data System (ADS)

In this study, spinach plants were grown under atmospheric and low pressure conditions with constant O2 and CO2 partial pressures, and the effects of low total pressure on gas exchange rates were investigated. CO2 assimilation and transpiration rates of spinach grown under atmospheric pressure increased after short-term exposure to low total pressure due to the enhancement of leaf conductance. However, gas exchange rates of plants grown at 25 kPa total pressure were not greater than those grown at atmospheric pressure. Stomatal pore length and width were significantly smaller in leaves grown at low total pressure. This result suggested that gas exchange rates of plants grown under low total pressure were not stimulated even with the enhancement of gas diffusion because the stomatal size and stomatal aperture decreased.

Iwabuchi, K.; Kurata, K.

301

Simulating uptake and transport of TNT by plants using STELLA.  

PubMed

Understanding the uptake and transport of soil organic contaminants by plants is crucial to a successful application of phytoremediation technique. This study investigated the removal of 2,4,6-trinitrotoluene (TNT) from a contaminated sandy soil by a poplar tree (Populus fastigiata) through the examinations of temporal variations of xylem water potential, leaf water transpiration, and root water and TNT uptake. A dynamic model for Uptake and Translocation of Contaminants from a Soil-Plant ecosystem (UTCSP), developed using the STELLA software package, was modified for the purpose of this study. The model was calibrated using laboratory measurements prior to its application. Simulation results showed that about 25% of TNT was removed from the soil by the poplar tree in 90 days. Simulations further revealed that the rates of water and TNT up taken by roots had a typical diurnal variation pattern: increasing during the day and decreasing during the night, resulting from daily variations of xylem water potentials that were caused by leaf water transpiration. In general, the storage of TNT mass in the roots decreased with time and occurred partially because of the low availability of soil TNT as time elapsed and partially because of the biodegradation of TNT in the plant tissues. This study suggests that the UTCSP model could be a useful tool for estimating phytoremediation of soil TNT by a plant. PMID:17655913

Ouyang, Ying; Huang, Cheng He; Huang, Dong Yi; Lin, Dian; Cui, Lihua

2007-07-25

302

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

303

A Soft-Sensor Method Based on Fuzzy Rules for Pulverized Coal Mass Flow Rate Measurement in Power Plant  

Microsoft Academic Search

A soft sensor method based on fuzzy rules for pulverized coal mass flow rate measurement in power plant is introduced, which used to resolve the problems of the electro dynamic sensor's deficiency in absolute mass flow rate measurement and the effect of flow regime on the output of the sensor. Abundant experimental data captured by special electrostatic sensor is pre-processed

Cheng Guixue; Pan Weiguo; Zhang Wei; Du Haizhou; Zhang Chao

2009-01-01

304

Influence of plant nutrient concentration on growth rate: Use of a nutrient interruption technique to determine critical concentrations of N, P and K in young plants  

Microsoft Academic Search

A method is described for determining the way in which growth rate varies with plant nutrient concentration using a simple\\u000a nutrient interruption technique incorporating only 2 treatments. The method involves measuring the changes in growth and nutrient\\u000a composition of otherwise well-nourished plants after the supply of one particular nutrient has been withheld. Critical concentrations\\u000a are estimated from the relationship between

I. G. Burns

1992-01-01

305

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

NASA Astrophysics Data System (ADS)

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, John; Woodruff, Steve; Straub, Douglas

2007-10-01

306

A High-Rate Secondary Treatment Based on a Moving Bed Bioreactor and Multimedia Filters for Small Wastewater Treatment Plants  

Microsoft Academic Search

For small wastewater treatment plants (WWPTs), high-rate secondary treatment systems with good treatment efficiency and easy, stable, and robust operation are called for. In this paper an experimental study on a high rate secondary treatment based on moving bed biofilm reactor (MBBR) and multimedia filters is presented. A high rate MBBR converts easily biodegradable SCOD in short HRT (0.5 h) directly

Z. Liao; V. Rasmussen; H. Ødegaard

2003-01-01

307

Increased vapor pressure deficit due to higher temperature leads to greater transpiration and faster mortality during drought for tree seedlings common to the forest-grassland ecotone.  

PubMed

Tree species growing along the forest-grassland ecotone are near the moisture limit of their range. Small increases in temperature can increase vapor pressure deficit (VPD) which may increase tree water use and potentially hasten mortality during severe drought. We tested a 40% increase in VPD due to an increase in growing temperature from 30 to 33°C (constant dewpoint 21°C) on seedlings of 10 tree species common to the forest-grassland ecotone in the southern Great Plains, USA. Measurement at 33 vs 30°C during reciprocal leaf gas exchange measurements, that is, measurement of all seedlings at both growing temperatures, increased transpiration for seedlings grown at 30°C by 40% and 20% for seedlings grown at 33°C. Higher initial transpiration of seedlings in the 33°C growing temperature treatment resulted in more negative xylem water potentials and fewer days until transpiration decreased after watering was withheld. The seedlings grown at 33°C died 13% (average 2 d) sooner than seedlings grown at 30°C during terminal drought. If temperature and severity of droughts increase in the future, the forest-grassland ecotone could shift because low seedling survival rate may not sufficiently support forest regeneration and migration. PMID:23718199

Will, Rodney E; Wilson, Stuart M; Zou, Chris B; Hennessey, Thomas C

2013-05-30

308

Sap Flow Estimate Of Watershed-Scale Transpiration  

NASA Astrophysics Data System (ADS)

The present study examined how to obtain sufficient information to extrapolate watershed-scale transpiration in a Japanese cedar (Cryptomeria japonica D. Don) forest from sap flow measurements of available individual trees. In this study, we conducted measurements of tree biometrics and tree-to-tree and radial variations in xylem sap flux density (Fd) in two different stand plots, an upper slope plot (UP) and lower slope plot (LP), during the growing season with significant variations in environmental factors. The manner in which the mean stand sap flux density (JS) and tree stem allometric relationship (diameter at breast height (DBH) versus sapwood area (AS_tree)) vary between the two stands along the slope of the watershed was then investigated. After these analyses, appropriate sample sizes for estimations of representative JS values in the stand were also determined. The results demonstrated that a unique or general function allowed description of the allometric relationship along the slope, but the data for its formulation needed to be obtained in both UP and LP. They also revealed that JS in UP and LP were almost the same during the study period despite differences in tree density and size between the two plots. This implies that JS measured in a partial stand within a watershed is a reasonable estimator of the values of other stands, and that stand sapwood area calculated by AS_tree is a strong determinant of water-use in a forest watershed. To estimate JS in both an UP and LP, at least 10 trees should be sampled, but not necessarily more than this.

Kumagai, T.; Aoki, S.; Shimizu, T.; Otsuki, K.

2006-12-01

309

Effects of height on treetop transpiration and stomatal conductance in coast redwood (Sequoia sempervirens).  

PubMed

Treetops become increasingly constrained by gravity-induced water stress as they approach maximum height. Here we examine the effects of height on seasonal and diurnal sap flow dynamics at the tops of 12 unsuppressed Sequoia sempervirens (D. Don) Endl. (coast redwood) trees 68-113 m tall during one growing season. Average treetop sap velocity (V(S)), transpiration per unit leaf area (E(L)) and stomatal conductance per unit leaf area (G(S)) significantly decreased with increasing height. These differences in sap flow were associated with an unexpected decrease in treetop sapwood area-to-leaf area ratios (A(S):A(L)) in the tallest trees. Both E(L) and G(S) declined as soil moisture decreased and vapor pressure deficit (D) increased throughout the growing season with a greater decline in shorter trees. Under high soil moisture and light conditions, reference G(S) (G(Sref); G(S) at D = 1 kPa) and sensitivity of G(S) to D (-?; dG(S)/dlnD) significantly decreased with increasing height. The close relationship we observed between G(Sref) and -? is consistent with the role of stomata in regulating E(L) and leaf water potential (?(L)). Our results confirm that increasing tree height reduces gas exchange of treetop foliage and thereby contributes to lower carbon assimilation and height growth rates as S. sempervirens approaches maximum height. PMID:20631010

Ambrose, Anthony R; Sillett, Stephen C; Koch, George W; Van Pelt, Robert; Antoine, Marie E; Dawson, Todd E

2010-07-14

310

Coupled hydraulic and photosynthetic feedbacks on forest transpiration throughout the growing season  

NASA Astrophysics Data System (ADS)

Ecosystem models account for vegetative controls on water fluxes using environmental drivers and hydraulic and/or biochemical limits on canopy stomatal conductance (Gs), variations in space and time of leaf area index (L), and species or biome specific parameters. However, some parameters, such as maximum stomatal conductance or its reference proxy at vapor pressure deficit of 1 kPa (Gsref), may not be strictly time-independent suggesting as yet undefined mechanisms in the models. We developed a model of coupled canopy water and carbon exchange, which allowed us to examine photosynthetic and hydraulic feedbacks on Gsref spanning the whole growing season for several dominant tree species in wetland and upland positions that collectively account for most a 1600 square km region centered on the WLEF AmeriFlux tower in Wisconsin, USA. The model assimilated half-hourly sap flux and micrometeorological data to quantify and explain temporal variations in Gsref for trembling aspen, sugar maple, and red pine in upland sites, and speckled alder and white cedar in wetland sites. Results show (1) phenological effects on photosynthetic activity with feedback on Gsref in all species, and (2) lags of up to two months between maximum per unit leaf area photosynthetic rates for conifer versus deciduous species. These results show that for given environmental conditions canopy transpiration depends on both L and timing of biochemical activation, both of which have implications for regional ecosystem water cycling.

Mackay, D. S.; Ewers, B. E.

2007-12-01

311

Characterization of Transpiration in a Deciduous Forest of the US Midwest  

NASA Astrophysics Data System (ADS)

The exchange of water between atmosphere and biosphere is an important determinant of climate and the productivity of vegetation, as transpiration involves substantial amounts of energy. Knowing how transpiration changes over seasonal and diurnal cycles can help increase the understanding of how a forest reacts to changes in the biosphere and atmosphere on both short and long time scales. A study was conducted to characterize the daily and seasonal variation of transpiration in sugar maple (Acer Saccharum) at the Morgan-Monroe State Forest (MMSF) AmeriFlux site in Indiana (USA), were this species represent more than 25% of the forest basal area. Transpiration was estimated by up-scaling single point measurements of sap flow density obtained using the heat-pulse technique. To characterize the variability of sap flow density in the deep sapwood of sugar maples, 3 to 4 radial profiles were obtained for each sampled tree at different positions around the trunk. Different approaches were then tested to scale up to whole tree sap flow. Seventeen trees of different diameter were sampled by three roving sap flow systems, taking measurements from each tree for 5-7 contiguous days. Because of the small scale but complex topography in the area and the relatively shallow soil, particular attention was given to the effect of spatial and temporal variability of soil moisture content on transpiration; for this reason, sampled trees were selected along a topographic gradient and soil water content was measured in the proximity of each tree. Meteorological measurements taken at the nearby MMSF AmeriFlux tower were used to explain transpiration variability in terms of vapor pressure deficit, and solar radiation, while eddy- covariance measurements of latent heat flux were related to the up-scaled transpiration of sugar maples in the study area.

Dragoni, D.; Caylor, K. K.; Schmid, H.

2006-12-01

312

Mathematical modeling riparian vegetation zonation in semiarid conditions based on a transpiration index.  

NASA Astrophysics Data System (ADS)

Initially riparian vegetation modeling was focused on the study of ecological patches without taking into account the interactive effects of structures and processes in between them (Tabacchi et al., 1998). One of the greatest challenges, when carrying out a riparian ecosystem restoration, is to understand the physical and ecological processes of a system and the interaction and feedback within these processes. Jorde (2002) pointed out the importance of addressing complex linkages between processes and biotic interactions in research and in the development of restoration projects over larger spatial and temporal scales in the future. According to Tabacchi et al. (2000), the water cycle in riparian zones depends on three important relations: the water absorption by the plants, water storage and atmospherical return by evaporation. During recent years a variety of ecological models have taken into account the changes in the plant species as consequence of changes in the environmental variables and hydrological alterations (Baptist, 2005; Braatne et al., 2002; Glenz, 2005; Hooke et al., 2005; Murphy et al., 2006). Most of these models are based on functional relationships between river hydrology and vegetation species or communities. In semiarid regions we make the hypothesis transpiration will be one of the key factors determining the riparian vegetation presence and therefore, we will not consider in our model other factors as recruitment, flood damages, etc. The objectives of this work are: firstly to develop a model capable of simulating several riparian vegetation types which can be applied in a wide range of conditions across Mediterranean environments; and secondly to calibrate and to validate the model in several Mediterranean river stretches of the Iberian Peninsula, both in undisturbed and disturbed flow regimes. To achieve these objectives the following methodology has been applied. The model has been conceptualized as a static tank flow model based on the actual evapotranspiration of the riparian plants. This tank represents a portion of soil of the superficial root layer. The lower capacity limit of this tank is the permanent wilting moisture of the soil sample. On the other hand the upper capacity limit is the field capacity moisture. The tank's input flows are the precipitation, the root water rise and the capillary water rise. In contrast output flows are the actual evapotranspiration and the excess water of the tank. The most relevant model parameters are the soil retention curves, vegetation functional type parameters (specially related to root depths and the transpiration efficiency factors) and the daily hidro-meteorological data, which are water table elevation, precipitation and potential evapotranspiration. The model runs for a limited amount of vegetation functional types. In our simulations the following four functional types were used: Riparian Herbs; Riparian Juveniles and Small Scrubs, Riparian Trees and Big Shrubs; and Terrestrial Vegetation. The general model output variable is an evapotranspiration index based in the quotient between the current and the potential evapotranspiration. This index is used to determine the suitability of the simulated vegetation functional types to certain environmental conditions. Secondly, a sensitivity analysis was made for determining the most relevant model parameters. Finally the model has been calibrated and validated using as objective function a confusion matrix which compares the observed and the simulated riparian vegetation zonation. The calibration/validation processes have been carried out in seven study sites of the Jucar River Basin District. Four of those sites have a natural flow regime and three of them a regulated flow regime due to the presence of dams. Results have shown that the model is capable of providing effective simulations in compared to the observed riparian vegetation.

Real, Joaquin; Morales, Marco; Garcia, Alicia; Garofano, Virginia; Martinez-Capel, Francisco; Frances, Felix

2010-05-01

313

Model-derived dose rates per unit concentration of radon in air in a generic plant geometry.  

PubMed

A model for the derivation of dose rates per unit radon concentration in plants was developed in line with the activities of a Task Group of the International Commission on Radiological Protection (ICRP), aimed at developing more realistic dosimetry for non-human biota. The model considers interception of the unattached and attached fractions of the airborne radon daughters by plant stomata, diffusion of radon gas through stomata, permeation through the plant's epidermis and translocation of deposited activity to plant interior. The endpoint of the model is the derivation of dose conversion coefficients relative to radon gas concentration at ground level. The model predicts that the main contributor to dose is deposition of (214)Po ?-activity on the plant surface and that diffusion of radon daughters through the stomata is of relatively minor importance; hence, daily variations have a small effect on total dose. PMID:21739195

Vives i Batlle, J; Smith, A; Vives-Lynch, S; Copplestone, D; Pröhl, G; Strand, T

2011-07-08

314

The search for optimum condenser cooling water flow rate in a thermal power plant  

Microsoft Academic Search

Heat losses from the thermal power plant cycle are due mainly to heat rejection through the condenser. Operating the condenser at optimum circulation water flowrate is essentially important to ensure maximum efficiency and minimum operating cost of the plant. In this study, computer program codes were developed in Microsoft Excel macros for simulation of a thermal plant at various circulation

A. N. Anozie; O. J. Odejobi

2011-01-01

315

Development of Plus Ultrasonic Doppler Method for Flow Rate Measurements of Power Plant: Multi-line Flow Rate Measurement for Non Developed Flow  

SciTech Connect

Flow metering system is being developed using plus ultrasonic Doppler method. The principle is an integration of instantaneous velocity profile over a pipe diameter so that it is expected to be able to eliminate installation problems such as entry length as well as to follow transient flow rate precisely. Flow metering principle by plus ultrasonic Doppler method in a circular pipe depends on the alignment of measuring lines. In this paper, influence of number of measuring lines on the flow rate measurements for power plant have been investigated for non developed flows in a vertical pipe. (authors)

Hiroshige Kikura; Sanehiro Wada; Masanori Aritomi [Tokyo Institute of Technology, O-okayama, Meguro-ku, Tokyo 152 (Japan); Michitsugu Mori [The Tokyo Electric Power Company, Incorporated, 1-3, Uchisaiwai-cho 1-chome, Chiyoda-ku, Tokyo, 1008560 (Japan); Yasushi Takeda [Paul Scherrer Institut, 5232 Villigen PSI (Switzerland)

2002-07-01

316

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

2009-10-15

317

Numerical simulation of gas-phonon coupling in thermal transpiration flows  

NASA Astrophysics Data System (ADS)

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.

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

2009-10-01

318

An in vivo root hair assay for determining rates of apoptotic-like programmed cell death in plants  

PubMed Central

In Arabidopsis thaliana we demonstrate that dying root hairs provide an easy and rapid in vivo model for the morphological identification of apoptotic-like programmed cell death (AL-PCD) in plants. The model described here is transferable between species, can be used to investigate rates of AL-PCD in response to various treatments and to identify modulation of AL-PCD rates in mutant/transgenic plant lines facilitating rapid screening of mutant populations in order to identify genes involved in AL-PCD regulation.

2011-01-01

319

Monte Carlo modelling and real-time dosemeter measurements of dose rate distribution at a 60Co industrial irradiation plant  

NASA Astrophysics Data System (ADS)

The dose rate distribution in a MDS Nordion JS7500 60Co industrial irradiation plant has been calculated using the egspp Monte Carlo code. This code is a development of the established EGSnrc code developed and distributed by National Research Council of Canada. The coding method is described and absolute dose rates given for each of the dwell positions in the path through the irradiator. These calculated dose rates have been compared with measurements made using a radiation resistant electronic dosimetry system. In addition, the integral dose derived from calculated and measured dose rates has been compared to the value obtained using chemical dosimeters.

Bailey, M.; Sephton, J. P.; Sharpe, P. H. G.

2009-07-01

320

PIP1 plasma membrane aquaporins in tobacco: from cellular effects to function in plants.  

PubMed

The molecular functions of several aquaporins are well characterized (e.g., by analysis of aquaporin-expressing Xenopus oocytes). However, their significance in the physiology of water transport in multicellular organisms remains uncertain. The tobacco plasma membrane aquaporin NtAQP1 was used to elucidate this issue. By comparing antisense plants that were inhibited in NtAQP1 expression with control plants, we found evidence for NtAQP1 function in cellular and whole-plant water relations. The consequences of a decrease in cellular water permeability were determined by measurement of transpiration rate and stem and leaf water potential as well as growth experiments under extreme soil water depletion. Plants impaired in NtAQP1 expression showed reduced root hydraulic conductivity and lower water stress resistance. In conclusion, our results emphasize the importance of symplastic aquaporin-mediated water transport in whole-plant water relations. PMID:11971141

Siefritz, Franka; Tyree, Melvin T; Lovisolo, Claudio; Schubert, Andrea; Kaldenhoff, Ralf

2002-04-01

321

The role of planted forests in urban water budgets (Invited)  

NASA Astrophysics Data System (ADS)

In arid regions which are not naturally forested, urban trees are sustained through the redistribution of water resources as irrigation. Assessments of outdoor water use in Southwestern US cities have shown that not only is 30-75% of residential water use expended on outdoor landscapes, but that irrigation is frequently in excess of estimated plant demand. Thus, there is a need to understand the factors which influence the magnitude and variability of water use of urban trees. A complicating factor in assessing urban tree water use is the widely recognized heterogeneity of urban environments. Human choices and decision-making result in a landscape with significant variability in water and nutrient inputs, microclimate, biotic inputs and vegetation composition. In order to quantify urban tree water use and explain variation in water use resulting from variability in resource availability and species composition, we have conducted a combination of sapflux, growth and isotopic studies on more than 35 common (primarily non-native) tree species in the Los Angeles basin. The objective of these studies was to determine how much variability in water use and water use efficiency exists within and between commonly planted urban tree species, and what factors explain or can be used to predict this variability. Through these studies we have found considerable differences (up to two fold) in tree transpiration within a given species, attributable to differences in water and nutrient availability and tree planting density. Additionally, we have found substantial variation in the water use of different species: at typical urban planting densities, peak transpiration rates can be more than ten times greater for high transpiring trees than low transpiring trees. Finally, we found whole tree water use efficiency to vary across species by a factor of up to a hundred, explained to a large degree by the climate conditions (especially vapor pressure deficit) in the native ranges of these non-native trees. On the scale of the entire city of Los Angeles, we estimate that the urban forest could use as much as 50% of the total municipal water use. Overall, we have found that urban trees can use substantial quantities of water, and that species choice matters greatly in determining urban landscape water use.

McCarthy, H. R.; Pataki, D. E.; Litvak, E.

2009-12-01

322

Mapped quadrats in sagebrush steppe: long-term data for analyzing demographic rates and plant-plant interactions.  

Technology Transfer Automated Retrieval System (TEKTRAN)

This historical dataset consists of a series of permanent 1-m2 quadrats located on the sagebrush steppe in eastern Idaho, USA. The key aspect of the data is that during each growing season, all individual plants in each quadrat were identified and mapped. The combination of a long time-series with f...

323

Rates of plant succession, carbon and nitrogen accumulation in small-scale tundra chronosequences; an implication for climate change  

NASA Astrophysics Data System (ADS)

The rate in which plants are able to colonize and build up soil organic carbon (SOC) and nitrogen (N) in soil are crucial in understanding the effect of environmental changes on high latitude ecosystems via plant community. In this presentation we present high-spatial-resolution data of plant colonization and SOC and N accumulation rates occurring on frost boils that are common in many periglacial landscapes. The diameters of each frost boil ranges from 1 to 3 meters. The distribution of plant community across a frost boil can be identified as a gradient of ongoing primary succession. The primary succession is initiated in the centre of the frost boil every time up-frozen soil is deposited on top of the surface. A subsequent lateral mass-movement of newly deposited soil from the centre of the frost boil towards the rim over time causes the surface soil and plant community to become progressively "older" from the centre towards the rim of the frost boil. In the presented work we constrain the age of the soil surface as a function of distance from the centre of the frost boil towards the rim by using lichenometry dating. With this investigation, we achieve soil age gradients (chronosequences) ranging from approximately from 0 to 300 years for meters-scale. We present data from northern Sweden where we have utilized this small-scale variation in soil age to understand how the accumulation rate of SOC and N varies over time in the upper 10 cm of the arctic soil and how the accumulation rates is affected by other ecosystem properties such as temperature, plant diversity, dominant plant functional groups and litter quality. Our key conclusions is that reduced soil frost actions, which is likely to accompany the predicted warming of the Scandinavian arctic, are likely to accelerate the colonization rate of vegetation that will enhance the accumulation of SOC and N. However, one likely side effect of this colonization into previously frost-disturbed system is the decline in spatial heterogeneity of plant community structure in tundra systems. Reference Makoto, K and Klaminder, J. (in review) The influence of non-sorted circles on species diversity of vascular plant, moss and lichens in sub-arctic tundra. Arct Antarct Alp Res.

Kobayashi, M.; Klaminder, J.

2011-12-01

324

Photosynthetic Rate, Growth, and Yield of Mustard Plants Sprayed with 28-Homobrassinolide  

Microsoft Academic Search

Thirty-day-old plants of mustard (Brassica juncea L.) were sprayed with 10?10, 10?8, or 10?6 M aqueous solution of 28-homobrassinolide (HBR). The HBR-treated plants were healthier than those treated with water and\\u000a yielded more. Maximum increase over control was found in 60-d-old, 10?8 M-HBR-treated plants in fresh and dry mass per plant, carbonic anhydrase (CA, E.C. 4.2.1.1) activity, and net photosynthetic

S. Hayat; A. Ahmad; M. Mobin; A. Hussain; Q. Fariduddin

2001-01-01

325

The Relationship of School Size and Rate of School Plant Utilization to Cost Variations of Maintenance and Operation  

ERIC Educational Resources Information Center

The effects of school size and school plant utilization on pupil costs of maintenance and operation (M & O) in a large city school system in the South were investigated. School size is significantly and negatively related to pupil costs of M & O. Utilization rate, computed by dividing average daily attendance by the design capacity of the school…

McGuffey, Carroll W.; Brown, Carvin L.

1978-01-01

326

Effect of morphological traits of plant, head and seed of sunflower hybrids on house sparrow damage rate  

Microsoft Academic Search

Birds are important key pests of sunflower crops in many countries. In this study, 615 heads and 5429 seeds of 31 sunflower hybrids (single cross, three-way cross and introduced hybrids) were randomly selected and rates of bird damage were estimated at the Plant Breeding Research Institute of Karaj during the summer of 2004–2005. The Spearman correlation test showed a significant

Abolghasem Khaleghizadeh

2011-01-01

327

Effect of plant density and nitrogen rates upon the leaf area of seed sugar beet on seed yield and quality  

Microsoft Academic Search

Three-year field trials were set up on eutric brown soil in northwestern Croatia (Zagreb) with the objective to determine the effect of plant density and nitrogen rates on the formation and size of leaf area of seed sugar beet, and on the yield and seed quality in seed production without transplanting. Investigations should also reveal how much the yield and

M. Pospišil; A. Pospišil; M. Rastija

2000-01-01

328

Storage and transpiration have negligible effects on delta13C of stem CO2 efflux in large conifer trees.  

PubMed

Stem respiration rates are often quantified by measuring the CO(2) efflux from stems into chambers. It has been suggested that these measurements underestimate respiration because some of the respired CO(2) can be either retained or transported upwards in the transpiration stream. If the stem CO(2) efflux does not represent all respired CO(2), then the interpretation of its isotopic signal may be compromised as well. The C-isotope composition of the respired CO(2) and the measured efflux could differ due to (i) the release of CO(2) produced elsewhere into the stem and transported upwards in xylem water (soil CO(2) or root respired CO(2)); (ii) the retention or release of CO(2) storage pools within the tree stem and (iii) the removal of CO(2) by the transpiration stream. We investigated the effects of these processes in large conifer trees using two manipulative experiments: a labelling experiment and a crown removal experiment. The labelling experiment used an extreme enrichment of dissolved CO(2) in soil water to assess the C uptake by the roots. In this experiment, we found no contamination of the stem CO(2) pool despite clear evidence that the water itself had been taken up. The crown removal experiment tested for vertical CO(2) flux in xylem water by eliminating transpiration. Here, we found no change in the delta(13)C of stem CO(2) efflux (delta(EA); P > 0.05). We concluded that for these large conifers, sap-flow influenced neither delta(13)C of stem efflux nor that of the stem CO(2) pool. By parameterizing Henry's Law for conditions inside the stem, we estimated the transport flux to represent 1-3% of the stem CO(2) efflux to the atmosphere. Finally, assuming a 2 per thousand difference between delta(13)C of root and stem respiration, we estimated that potential contamination of delta(EA) by root respired CO(2) would be < 0.1 per thousand. Thus, neither the release of soil or root CO(2), nor storage in the stem, nor vertical transport of CO(2) in the xylem sap had any detectable influence on delta(13)C of the CO(2) measured in stem efflux. PMID:19840994

Ubierna, Nerea; Kumar, Arjun S; Cernusak, Lucas A; Pangle, Robert E; Gag, Peter J; Marshall, John D

2009-10-19

329

Simulation tools for evaluating optical plant sensors for variable-rate application technology  

NASA Astrophysics Data System (ADS)

A significant reduction in the amount of pesticides applied in agricultural and biological systems could be achieved using spot spray technology. To accomplish this, advanced plant sensor systems must be developed that can accurately locate and identify weeds from crop plants in the field. Currently, both public and commercial efforts have concentrated on single element optical sensors based on key reflective elements of the plant and soil system. Machine vision or image analysis is being investigated as another possible tool in plant sensing. It may provide valuable optical design information for less expensive single-element sensors. Moreover, shape features and textural analysis already provides simple broadleaf-grass classification based on staged plant images. These have not been thoroughly field tested. Another approach is to test image analysis algorithms, using three-dimensional rendering of weed and plant canopy architecture under complex lighting regimes. What was essentially done was to extract plant shape and textural information, along with essential physiological data from actual photographic images and then reassemble them as a virtual plant in the computer. A dissection program was written in C and efficiently extracts and stores irregular leaf shape and texture data. A canopy architecture program was written in C and Media Cybernetics HALOR graphics routines under DOS Expanded Memory on a personal computer. The plant simulation model consists of a three dimensional space where simulated light rays are generated as diffuse or speculative illumination. Plant surfaces are simulated with actual textural maps. The virtual plant is then manipulated to generate images that would be seen with machine vision. Computer simulated weed images were used to generate and test different fields of view sizes for evaluating how single element optical sensors would respond to composite leaf-soil reflectance.

Meyer, George E.; Hindman, Timothy W.; Schultz, Mark

1996-12-01

330

Common cause fault rates for diesel generators: estimates based on licensee event reports at US commercial nuclear power plants, 1976-1978  

Microsoft Academic Search

This report presents estimates of common cause fault rates and related quantities, based on Licensee Event Reports for diesel generators in nuclear reactors. The Licensee Event Report data base is described. For estimating rates, the bionomial failure rate model is used, extended to allow for the substantial observed plant-to-plant variability, and for shocks that by their nature make all the

C. L. Atwood; J. A. Steverson

1982-01-01

331

Hydrogen peroxide dry deposition lifetime determined from observed loss rates in a power plant plume  

Microsoft Academic Search

Hydrogen peroxide measurements made aboard the NOAA WP-3D aircraft in the summer of 1995 as part of the Southern Oxidants Study revealed loss of hydrogen peroxide within fossil fuel power plant plumes and the Nashville urban plume. On July 7 the Cumberland power plant plume was intercepted at five different downwind distances. H202 mixing ratios within the plume decreased with

B. T. Jobson; G. J. Frost; S. A. McKeen; T. B. Ryerson; M. P. Buhr; D. D. Parrish; F. C. Fehsenfeld

1998-01-01

332

Transcription Factor Families Have Much Higher Expansion Rates in Plants than in Animals  

Microsoft Academic Search

Transcription factors (TFs), which are central to the regulation of gene expression, are usually members of multigene families. In plants, they are involved in diverse processes such as developmental control and elicitation of defense and stress responses. To investigate if differences exist in the expansion patterns of TF gene families between plants and other eukaryotes, we first used Arabidopsis (Arabidopsis

Shin-Han Shiu; Ming-Che Shih; Wen-Hsiung Li

2005-01-01

333

Regulation of growth and nutrient uptake under different transpiration regimes  

Microsoft Academic Search

To determine the extent to which air humidity affects the regulation of nutrient demand, an experiment with tomato plants was carried out under fully controlled climate conditions. Treatments consisted of three levels of relative air humidity (RH): 50%, 70% (control) and 95%, corresponding to 1.32, 0.79 and 0.13 kPa vapour pressure deficit (VPD), respectively. High humidity reduced the total plant

Amor del F. M; L. F. M. Marcelis

2005-01-01

334

Plants  

NSDL National Science Digital Library

Get ready to explore plants! Let's Learn About Plants! Question: What do plants need to live? Watch the video to find out! What does it need to grow? Question: What are the parts of a plant? Click to find out! Parts of a Plant Question: What is the life cycle of a plant? Watch the video to find out! Plant Life Cycle Video Question: ...

Berneski, Miss

2011-12-10

335

Potential Usefulness of Antitranspirants for Increasing Water Use Efficiency in Plants.  

National Technical Information Service (NTIS)

Antitranspirants conserve water and maintain favorable plant water balances by reducing stomatal apertures, by forming a thin film over the leaves, or by reflecting excessive radiation. Under normal conditions, reductions in both transpiration and photosy...

R. M. Hagan D. C. Davenport

1970-01-01

336

Seasonal photosynthetic gas exchange and water-use efficiency in a constitutive CAM plant, the giant saguaro cactus (Carnegiea gigantea).  

PubMed

Crassulacean acid metabolism (CAM) and the capacity to store large quantities of water are thought to confer high water use efficiency (WUE) and survival of succulent plants in warm desert environments. Yet the highly variable precipitation, temperature and humidity conditions in these environments likely have unique impacts on underlying processes regulating photosynthetic gas exchange and WUE, limiting our ability to predict growth and survival responses of desert CAM plants to climate change. We monitored net CO(2) assimilation (A(net)), stomatal conductance (g(s)), and transpiration (E) rates periodically over 2 years in a natural population of the giant columnar cactus Carnegiea gigantea (saguaro) near Tucson, Arizona USA to investigate environmental and physiological controls over carbon gain and water loss in this ecologically important plant. We hypothesized that seasonal changes in daily integrated water use efficiency (WUE(day)) in this constitutive CAM species would be driven largely by stomatal regulation of nighttime transpiration and CO(2) uptake responding to shifts in nighttime air temperature and humidity. The lowest WUE(day) occurred during time periods with extreme high and low air vapor pressure deficit (D(a)). The diurnal with the highest D(a) had low WUE(day) due to minimal net carbon gain across the 24 h period. Low WUE(day) was also observed under conditions of low D(a); however, it was due to significant transpiration losses. Gas exchange measurements on potted saguaro plants exposed to experimental changes in D(a) confirmed the relationship between D(a) and g(s). Our results suggest that climatic changes involving shifts in air temperature and humidity will have large impacts on the water and carbon economy of the giant saguaro and potentially other succulent CAM plants of warm desert environments. PMID:21822726

Bronson, Dustin R; English, Nathan B; Dettman, David L; Williams, David G

2011-08-06

337

Hydrogen peroxide dry deposition lifetime determined from observed loss rates in a power plant plume  

Microsoft Academic Search

Hydrogen peroxide measurements made aboard the NOAA WP-3D aircraft in the summer of 1995 as part of the Southern Oxidants Study revealed loss of hydrogen peroxide within fossil fuel power plant plumes and the Nashville urban plume. On July 7 the Cumberland power plant plume was intercepted at five different downwind distances. H2O2 mixing ratios within the plume decreased with

B. T. Jobson; G. J. Frost; S. A. McKeen; T. B. Ryerson; M. P. Buhr; D. D. Parrish; F. C. Fehsenfeld

1998-01-01

338

Plant controls on decomposition rates: the benefits of restoring abandoned agricultural lands with native prairie grasses  

Microsoft Academic Search

Plant species can both directly and indirectly affect soil processes in various ways, including through functional traits\\u000a related to the quantity and chemistry of biomass produced. Understanding how functional traits affect soil processes may be\\u000a particularly important in restorations that specifically select a target plant community. In this study, I examined how species\\u000a differing in litter traits alter decomposition, both

Wendy M. Mahaney

2010-01-01

339

A SIMPLE AND COST-EFFECTIVE METHOD TO SCREEN FOR TRANSPIRATION EFFICIENCY IN SORGHUM  

Technology Transfer Automated Retrieval System (TEKTRAN)

Sorghum [Sorghum bicolor (L.) Moench] is a widely-grown cereal grain and a dietary staple for more than 500 million people worldwide. Sorghum is grown primarily in arid and semi-arid regions with no or limited irrigation. Enhanced transpiration efficiency (TE), defined as total biomass produced per...

340

Prediction of transpiration effects on heat and mass transfer by different turbulence models  

Microsoft Academic Search

The paper reports the results of a study related to transpirating flows, stimulated by the interest that these phenomena, occurring in the presence of simultaneous heat and mass transfer, have for nuclear reactor applications. The work includes a summary and the follow-up of previous experimental and numerical investigations on filmwise condensation and falling film evaporation and of a recent review

M. Bucci; M. Sharabi; W. Ambrosini; N. Forgione; F. Oriolo; S. He

2008-01-01

341

Flow distribution in unglazed transpired plate solar air heaters of large area  

Microsoft Academic Search

Unglazed transpired plate solar air heaters have proven to be effective in heating outside air on a once-through basis for ventilation and drying applications. Outside air is sucked through unglazed plates having uniformly distributed perforations. The air is drawn into a plenum behind the plate and then supplied to the application by fans. Large collectors have been built that cover

L. H. Gunnewiek; E. Brundrett; K. G. T. Hollands

1996-01-01

342

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...

343

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

344

Inferences of Competitive Effects on Transpiration from Spatial Patterns in Stomatal Conductance.  

NASA Astrophysics Data System (ADS)

Stand level spatial homogeneity for transpiration is assumed and therefore spatial components are not incorporated in models. We have found whole tree sapflux to vary spatially within species for aspen ( Populus Tremuloides) along a moisture gradient in northern Wisconsin. As such we expect simulated values of reference stomatal conductance (GSref) derived from sap flux data to vary spatially as well. Sap flux data collected using a cyclic sampling design intended for geostatistical analysis was used to test this hypothesis. This data was collected over 10 days on a 1.5 ha site near the WLEF AmeriFlux tower in the Chequmegon National Forest in northern Wisconsin. We used the Terrestrial Regional Ecosystem Exchange Simulator (TREES) model to simulate values of GSref for individual trees. Geostatistical analyses indicate spatial autocorrelation among whole tree sap flux and simulated GSref values for aspen and alder ( Alnus incana). Environmental variables such as soil moisture and vapor pressure deficit that are thought to drive transpiration may explain some, but not all, of this spatial variability. One hypothesis is that competition may influence transpiration at the tree level. We explore the possibility that whole tree transpiration is influenced by the location and stature of neighboring individuals.

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

2005-12-01

345

Effect of solar loading on greenhouse containers used in transpiration efficiency screening  

Technology Transfer Automated Retrieval System (TEKTRAN)

Earlier we described a simple high throughput method of screening sorghum for transpiration efficiency (TE). Subsequently it was observed that while results were consistent between lines exhibiting high and low TE, ranking between lines with similar TE was variable. We hypothesized that variable mic...

346

Compressible Turbulent Boundary Layers with Discontinuous Air Transpiration: An Experimental and Theoretical Investigation.  

National Technical Information Service (NTIS)

Experimental data are presented for the development of compressible turbulent boundary layers moving from a solid into a transpired surface, and vice versa. The data were obtained at free stream Mach numbers of 1.8 and 3.6 (Reynolds numbers per meter of 2...

P. G. Marriott

1977-01-01

347

Modeling respiration–transpiration in a modified atmosphere packaging system containing blueberry  

Microsoft Academic Search

A respiration–transpiration model was developed by applying simultaneous heat and mass transfer principles along with known physiological behavior for the design of MAP systems containing fresh produce. The model equations were solved numerically using Adams–Moulton method to predict gas compositions, RH, and temperature in model packages. The applicability of the model to packages containing blueberry at 15 and 25 °C

Yoonseok Song; Nick Vorsa; Kit L Yam

2002-01-01

348

Towards a Bottom-Up Scaling Strategy for Regional Carbon and Water Cycling - Field Testing Simple Models for Ecosystem Assimilation and Transpiration  

NASA Astrophysics Data System (ADS)

Emerging international strategies to reduce greenhouse gas accumulation will rely on reliable regional- and continental-scale models of carbon and water cycling. To date, most regional estimates of carbon balance use a top-down scaling approach, which provides limited information about vegetative controls on land-atmosphere carbon and water vapor exchange. This study describes a model of ecosystem assimilation and transpiration that can be combined with meteorological Re-analysis data and satellite-derived land cover data to form a novel bottom-up scaling strategy over large land areas to further constrain regional-scale models of carbon and water cycling. Our model uses a Jarvis-type formulation to estimate bulk canopy conductance as a function of photosynthetic active radiation, vapor pressure deficit and soil moisture content. The conductance model is used to estimate Latent Heat Exchange (LE) and is combined with an assumed intercellular carbon dioxide concentration to model assimilation. Ecosystem transpiration is derived as the difference between modeled LE and evaporation as estimated with a simple radiation transfer model. As a logical step in scaling process, the assimilation and evapotranspiration models are field-tested with multiple years of eddy-covariance data from a successional gradient (grassland -- planted pine forest -- hardwood forest) in the Southeastern U.S. The sites have the same soil characteristics and climate, but differ in vegetation cover. Annual precipitation at our study site varied considerably during the study period (Jan 2002 -- Dec 2004), ranging from 260 mm below the long-term mean in 2002, and 150 mm above the mean in 2003. The study ecosystems differed in their response to these hydrologic perturbations, and the impacts of drought conditions on ecosystem assimilation and transpiration are discussed for each vegetation type.

Novick, K. A.; Katul, G. G.; Juang, J.; Siqueira, M. B.; Stoy, P. C.

2005-12-01

349

Effect of low dose gamma irradiation on plant and grain nutrition of wheat  

NASA Astrophysics Data System (ADS)

We recently reported the use of low dose gamma irradiation to improve plant vigor, grain development and yield attributes of wheat (Singh and Datta, 2010). Further, we report here the results of a field experiment conducted to assess the effect of gamma irradiation at 0, 0.01, 0.03, 0.05, 0.07 and 0.1 kGy on flag leaf area, stomatal conductance, transpiration and photosynthetic rate and plant and grain nutritional quality. Gamma irradiation improved plant nutrition but did not improve the nutritional quality of grains particularly relating to micronutrients. Grain carotene, a precursor for vitamin A, was higher in irradiated grains. Low grain micronutrients seem to be caused by a limitation in the source to sink nutrient translocation rather than in the nutrient uptake capacity of the plant root.

Singh, Bhupinder; Datta, Partha Sarathi

2010-08-01

350

C3 plants enhance rates of photosynthesis by reassimilating photorespired and respired CO2.  

PubMed

Photosynthetic carbon gain in plants using the C(3) photosynthetic pathway is substantially inhibited by photorespiration in warm environments, particularly in atmospheres with low CO(2) concentrations. Unlike C(4) plants, C(3) plants are thought to lack any mechanism to compensate for the loss of photosynthetic productivity caused by photorespiration. Here, for the first time, we demonstrate that the C(3) plants rice and wheat employ a specific mechanism to trap and reassimilate photorespired CO(2) . A continuous layer of chloroplasts covering the portion of the mesophyll cell periphery that is exposed to the intercellular air space creates a diffusion barrier for CO(2) exiting the cell. This facilitates the capture and reassimilation of photorespired CO(2) in the chloroplast stroma. In both species, 24-38% of photorespired and respired CO(2) were reassimilated within the cell, thereby boosting photosynthesis by 8-11% at ambient atmospheric CO(2) concentration and 17-33% at a CO(2) concentration of 200 µmol mol(-1) . Widespread use of this mechanism in tropical and subtropical C(3) plants could explain why the diversity of the world's C(3) flora, and dominance of terrestrial net primary productivity, was maintained during the Pleistocene, when atmospheric CO(2) concentrations fell below 200 µmol mol(-1) . PMID:22734462

Busch, Florian A; Sage, Tammy L; Cousins, Asaph B; Sage, Rowan F

2012-07-23

351

Can the Giberella zeae toxin zearalenone affect the photosynthetic productivity and increase yield formation in spring wheat and soybean plants?  

Microsoft Academic Search

The seeds of soybean cv. Aldana and spring wheat cv. Torka were soaked for 24 h in solution of zearalenone [ZEN, 2,4-dihydroxy-6-(10-hydroxy-6-oxo-trans-1-undecenyl)-benzonic acid lactone, 4 mg dm?3] and then they were sown in the pot experiment in an open vegetation hall. The after-effects of ZEN on growth of plants,\\u000a net photosynthetic (P\\u000a N) and transpiration (E) rates, stomatal conductance (g

J. Ko?cielniak; J. Biesaga-Ko?cielniak; A. Janeczko; W. Filek; H. M. Kalaji

2009-01-01

352

Biomass or growth rate endpoint for algae and aquatic plants: relevance for the aquatic risk assessment of herbicides.  

PubMed

Ecotoxicological studies with algae and aquatic plants are essential parts of the aquatic risk assessment for crop protection products (CPP). Growth rate is used as a response variable and in addition the effects on biomass and/or yield (in the following biomass) can be measured. The parameter biomass generally provides a lower numerical value compared with the growth rate for systematic and mathematical reasons. Therefore, some regulators prefer to use the EbC50 value (i.e., the concentration at which 50% reduction of biomass is observed) rather than ErC50 (the concentration at which a 50% inhibition of growth rate is observed) as the endpoint for ecotoxicological risk assessment. However, the parameter growth rate is scientifically more appropriate and robust against deviations in test conditions, permitting better interpretation of, and comparison between, studies. The aim of the present work is to evaluate the growth rate and biomass parameters with regard to their protectiveness and suitability for environmental risk assessment of CPP. It has been shown for a number of herbicides that the use of the EC50 value (without distinction between growth rate and biomass endpoints) from laboratory studies in combination with an assessment factor of 10 is sufficiently protective for aquatic plants (except for the herbicide 2,4-D). In this paper we evaluated EbC50 and ErC50 values separately. Data on 19 different herbicides were compiled from the literature or GLP reports. The EbC50 and ErC50 values obtained in laboratory studies were compared with effect concentrations in ecosystem studies (mainly mesocosm). This comparison of laboratory and field data shows that the overall aquatic risk assessment using ErC50 values in combination with the currently applied assessment factor of 10 is sufficient to exclude significant risk to aquatic plants in the environment. PMID:20836059

Bergtold, Matthias; Dohmen, Gerhard Peter

2010-12-06

353

The metabolic signature related to high plant growth rate in Arabidopsis thaliana  

PubMed Central

The decline of available fossil fuel reserves has triggered world-wide efforts to develop alternative energy sources based on plant biomass. Detailed knowledge of the relations of metabolism and biomass accumulation can be expected to yield powerful novel tools to accelerate and enhance energy plant breeding programs. We used metabolic profiling in the model Arabidopsis to study the relation between biomass and metabolic composition using a recombinant inbred line (RIL) population. A highly significant canonical correlation (0.73) was observed, revealing a close link between biomass and a specific combination of metabolites. Dividing the entire data set into training and test sets resulted in a median correlation between predicted and true biomass of 0.58. The demonstrated high predictive power of metabolic composition for biomass features this composite measure as an excellent biomarker and opens new opportunities to enhance plant breeding specifically in the context of renewable resources.

Meyer, Rhonda C.; Steinfath, Matthias; Lisec, Jan; Becher, Martina; Witucka-Wall, Hanna; Torjek, Otto; Fiehn, Oliver; Eckardt, Anne; Willmitzer, Lothar; Selbig, Joachim; Altmann, Thomas

2007-01-01

354

The metabolic signature related to high plant growth rate in Arabidopsis thaliana.  

PubMed

The decline of available fossil fuel reserves has triggered world-wide efforts to develop alternative energy sources based on plant biomass. Detailed knowledge of the relations of metabolism and biomass accumulation can be expected to yield powerful novel tools to accelerate and enhance energy plant breeding programs. We used metabolic profiling in the model Arabidopsis to study the relation between biomass and metabolic composition using a recombinant inbred line (RIL) population. A highly significant canonical correlation (0.73) was observed, revealing a close link between biomass and a specific combination of metabolites. Dividing the entire data set into training and test sets resulted in a median correlation between predicted and true biomass of 0.58. The demonstrated high predictive power of metabolic composition for biomass features this composite measure as an excellent biomarker and opens new opportunities to enhance plant breeding specifically in the context of renewable resources. PMID:17360597

Meyer, Rhonda C; Steinfath, Matthias; Lisec, Jan; Becher, Martina; Witucka-Wall, Hanna; Törjék, Ottó; Fiehn, Oliver; Eckardt, Anne; Willmitzer, Lothar; Selbig, Joachim; Altmann, Thomas

2007-03-05

355

Correlation between Plant Growth Regulator Release Rate and Bioactivity for the Series of Newly Synthesized Phytoactive Polymers  

Microsoft Academic Search

Phytoactive polymers are high molecular weight systems in which a plant growth regulator (PGR) unit is attached to the polymeric\\u000a chain by a hydrolyzable chemical bond. The release rate of the PGR is linked to the biological activity of the phytoactive\\u000a polymer and can be controlled by properties inherent in the whole macromolecular system. In this study the correlation of

Michael I. Shtilman; Manolis N. Tzatzarakis; Potvakan S. Voskanyan; Ioannis N. Tsakiris; Andreas K. Tsakalof; Aristidis M. Tsatsakis

2006-01-01

356

Accumulation of cadmium in near-isogenic lines of durum wheat (Triticum turgidum L. var durum): the role of transpiration.  

PubMed

Concentrations of cadmium in the grain of durum wheat (Triticum turgidum L. var durum) are often above the internationally acceptable limit of 0.2 mg kg(-1). Cultivars that vary in concentrations of cadmium in the grain have been identified but the physiology behind differential accumulation has not been determined. Three pairs of near-isogenic lines (isolines) of durum wheat that vary in aboveground cadmium accumulation (8982-TL 'high' and 'low', W9260-BC 'high' and 'low', and W9261-BG 'high' and 'low') were used to test the hypothesis that the greater amounts of cadmium in shoots of the 'high' isolines are correlated with greater volumes of water transpired. In general, cadmium content was positively correlated with transpiration only in the 'low' isolines. Although shoots of the 'high' isolines of W9260-BC and W9261-BG contained higher concentrations of cadmium than did their corresponding 'low' isolines, they did not transpire larger volumes of water. In addition, isolines of 8982-TL transpired less water than did the other pairs of isolines yet both 'high' and 'low' isolines of 8982-TL contained higher amounts of cadmium than did the other pairs. The difference between 'high' and 'low' isolines appears to be related to the relative contribution of transpiration to cadmium translocation to the shoot. Increased transpiration was associated with increased cadmium content in the 'low' isolines but in the 'high' isolines increased cadmium in the shoot occurred independently of the volume of water transpired. PMID:23573025

Quinn, C J; Mohammad, A; Macfie, S M

2011-10-05

357

The non-equilibrium factor and the flashing evaporation rate inside the flash chamber of a multi-stage flash desalination plant  

Microsoft Academic Search

A study was undertaken to measure the non-equilibrium factor and to correlate the flashing evaporation rate inside the flash chamber of a multi-stage flash (MSF) desalination plant. A computer code was developed to quantitatively simulate the MSF desalination plant operation and solve the mass, heat and salt balance equations. The simulator was tested against an MSF pilot plant with a

Hassan E. S. Fath

1997-01-01

358

Advanced regulatory control and coordinated plant-wide control strategies for IGCC targeted towards 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

359

The effect of land plants on weathering rates of silicate minerals  

Microsoft Academic Search

Land plants and their associated microbiota directly affect silicate mineral weathering in several ways: by generation of chelating ligands, by modifying pH through production of CO 2 or organic acids, and by altering the physical properties of a soil, particularly the exposed surface areas of minerals and the residence time of water. In laboratory experiments far from equilibrium, 1 mM

James I. Drever

1994-01-01

360

Loss rate of NOy from a power plant plume based on aircraft measurements  

Microsoft Academic Search

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.

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

1998-01-01

361

The evolution of inquilinism, host-plant use and mitochondrial substitution rates in Tamalia gall aphids  

Microsoft Academic Search

We used mitochondrial DNA data to infer phylogenies for 28 samples of gall- inducing Tamalia aphids from 12 host-plant species, and for 17 samples of Tamalia inquilinus, aphid 'inquilines' that obligately inhabit galls of the gall inducers and do not form their own galls. Our phylogenetic analyses indicate that the inquilines are monophyletic and closely related to their host aphids.

D. G. Miller; B. Crespi

2003-01-01

362

Mechanism of Methane Transport from the Rhizosphere to the Atmosphere through Rice Plants 1  

PubMed Central

To clarify the mechanisms of methane transport from the rhizosphere into the atmosphere through rice plants (Oryza sativa L.), the methane emission rate was measured from a shoot whose roots had been kept in a culture solution with a high methane concentration or exposed to methane gas in the gas phase by using a cylindrical chamber. No clear correlation was observed between change in the transpiration rate and that in the methane emission rate. Methane was mostly released from the culm, which is an aggregation of leaf sheaths, but not from the leaf blade. Micropores which are different from stomata were newly found at the abaxial epidermis of the leaf sheath by scanning electron microscopy. The measured methane emission rate was much higher than the calculated methane emission rate that would result from transpiration and the methane concentration in the culture solution. Rice roots could absorb methane gas in the gas phase without water uptake. These results suggest that methane dissolved in the soil water surrounding the roots diffuses into the cell-wall water of the root cells, gasifies in the root cortex, and then is mostly released through the micropores in the leaf sheaths. Images Figure 7

Nouchi, Isamu; Mariko, Shigeru; Aoki, Kazuyuki

1990-01-01

363

Dynamic evolution of plant mitochondrial genomes: Mobile genes and introns and highly variable mutation rates  

Microsoft Academic Search

We summarize our recent studies showing that angiosperm mitochondrial (mt) genomes have experienced remarkably high rates of gene loss and concomitant transfer to the nucleus and of intron acquisition by horizontal transfer. Moreover, we find substantial lineage-specific variation in rates of these structural mutations and also point mutations. These findings mostly arise from a Southern blot survey of gene and

Jeffrey D. Palmer; Keith L. Adams; Yangrae Cho; Christopher L. Parkinson; Yin-Long Qiu; Keming Song

2000-01-01

364

A high-rate secondary treatment based on a moving bed bioreactor and multimedia filters for small wastewater treatment plants.  

PubMed

For small wastewater treatment plants (WWPTs), high-rate secondary treatment systems with good treatment efficiency and easy, stable, and robust operation are called for. In this paper an experimental study on a high rate secondary treatment based on moving bed biofilm reactor (MBBR) and multimedia filters is presented. A high rate MBBR converts easily biodegradable SCOD in short HRT (0.5 h) directly after screening, then a Kaldnes-Filtralite-Sand (KFS) filter removes the particulate COD and detached biofilms at filtration rates of 10-20 m/h. The whole system gave effluent SS and COD less than 30 mg/L and 100 mg/L when total detention time is less than 1 h and small dosage of chemicals (iron and/or cationic polymer) is used. A new scenario of high rate secondary system with a primary Kaldnes coarse media filter in front of high rate MBBR and the KFS filter is proposed and discussed. This scenario with total HRT less than 2h is more suitable for high influent SS concentrations and may also be extended for nitrogen and phosphorous removal. Compared to conventional secondary treatment, the high rate secondary treatment will be using only 1/5-1/10 of the space, resulting in considerable savings for construction, energy and operation. PMID:14524687

Liao, Z; Rasmussen, V; Odegaard, H

2003-01-01

365

Plants  

NSDL National Science Digital Library

What is the cycle plants go through? First use Write out the Plant Cycle Watch the Plant Powerpoint write down what you learned. Next watch the movie Plant Cycle Movie What did you think was interesting? Next, search around on the website and write down facts about plants. LIfe Cycle of Plants Next, play around with the part of the plants http://www.sciencekids.co.nz/gamesactivities/lifecycles.htmlFinally learn all about growing a plant. Growing a plant After you are finished come see me ...

Barron, Anne

2011-04-14

366

Is mass-based metabolism rate proportional to surface area in plant leaves? A data re-analysis.  

PubMed

We re-analyzed two large published databases on leaf traits of plant species from seven different biomes, and determined the scaling relationship between leaf metabolism rate (mass-based photosynthesis capacity, A(mass), and mass-based dark respiration, Rd(mass)) and specific leaf area (SLA) across biomes, using a standardized major axis (SMA) method. Overall pooled data produced a scaling exponent of 1.33 for the relationship between A(mass) and SLA, significantly larger than 1.0; and 1.04 between Rd(mass) and SLA. The scaling exponent of the relationship between A(mass) and SLA ranged between 1.23 (in tropical forest) and 1.66 (in alpine biome), and it was significantly larger in alpine (1.66) and grass/meadow (1.52) biomes than in tropical forest (1.23) and wetland (1.27). The exponent of the relationship between Rd(mass) and SLA, however, was much smaller in wetland (1.05) than in temperate forest (1.29) and tropical rainforest (1.65). In general, the predicated universal scaling relationship that the mass-based metabolism rate should be proportional to surface area in organisms is not applicable at the leaf-level in plants. Rather, the large slope difference of the relationship between leaf metabolism rate and SLA found among biomes indicates that the strength of the selective forces driving the scaling relationship is different among the biomes. The result basically suggests the importance of increasing SLA to plant carbon gain in stressful environments and to carbon loss in favorable habitats, and therefore has an important implication for survival strategies of plants in different biomes. PMID:18713407

Jin, Dongmei; Dai, Yiqiang; Sun, Li; Sun, Shucun

2008-06-01

367

Interspecific variation in nighttime transpiration and stomatal conductance in a mixed New England deciduous forest.  

PubMed

Transpiration is generally assumed to be insignificant at night when stomata close in response to the lack of photosynthetically active radiation. However, there is increasing evidence that the stomata of some species remain open at night, which would allow for nighttime transpiration if there were a sufficient environmental driving force. We examined nighttime water use in co-occurring species in a mixed deciduous stand at Harvard Forest, MA, using whole-tree and leaf-level measurements. Diurnal whole-tree water use was monitored continuously with Granier-style sap flux sensors in paper birch (Betula papyrifera Marsh.), red oak (Quercus rubra L.) and red maple (Acer rubrum L.). An analysis was conducted in which nighttime water flux could be partitioned between refilling of internal water stores and transpiration. Substantial nighttime sap flux was observed in all species and much of this flux was attributed to the refilling of depleted water stores. However, in paper birch, nighttime sap flux frequently exceeded recharge estimates. Over 10% of the total daily sap flux during the growing season was due to transpiration at night in paper birch. Nighttime sap flux was over 8% of the total daily flux in red oak and 2% in red maple; however, this flux was mainly associated with recharge. On nights with elevated vapor pressure deficit, sap flux continued through the night in paper birch, whereas it reached zero during the night in red oak and red maple. Measurements of leaf-level gas exchange on a night with elevated vapor pressure deficit showed stomatal conductance dropping by only 25% in paper birch, while approaching zero in red oak and red maple. The study highlighted differences in ecophysiological controls on sap flux exerted by co-occurring species. Paper birch is a fast-growing, shade-intolerant species with an earlier successional status than red oak and red maple. Risking water loss through nighttime transpiration may provide paper birch with an ecological advantage by enabling the species to maximize photosynthesis and support rapid growth. Nighttime transpiration may also be a mechanism for delivering oxygen to respiring cells in the deep sapwood of paper birch. PMID:16414920

Daley, Michael J; Phillips, Nathan G

2006-04-01

368

High outcrossing rates maintain male and hermaphrodite individuals in populations of the flowering plant Datisca glomerata  

Microsoft Academic Search

MODELS for the maintenance of androdioecy (the presence of male and hermaphrodite individuals in a breeding population) in plants predict that males must have a fertility at least double the male fertility of hermaphrodites in order to be maintained by selection1-3. An even greater advantage is required in partially self-fertilizing populations1-3 as the gain in fitness through increased pollen production

Peter Fritsch; Loren H. Rieseberg

1992-01-01

369

Metal-rich concretions on the roots of salt marsh plants: Mechanism and rate of formation  

Microsoft Academic Search

The roots of the vascular plant Spartina maritima, growing in the saltmarshes of the Tagus Estuary, Portugal, are surrounded by tubular concretions whose diameter can reach >0.2 cm. Concretions are also found scattered within the sediment matrix in and below the root zone. The concretions comprise 4% (DW) of the sediment and contain 11.7 2 1.6% iron compared to 4.9

Bjørn Sundby; Carlos Vale; Isabel Caçador; Fernando Catarino; Maria-João Madureira; Miguel Caetano

1998-01-01

370

Verde plant bug (Hemiptera: Miridae) feeding injury to cotton bolls characterized by boll age, size, and damage ratings.  

PubMed

The verde plant bug, Creontiades signatus (Distant), has been present in south Texas for several years but has more recently been documented as an economic threat to cultivated cotton, (Gossypium hirsutum L. Our studies over 2 yr (2009 and 2010) and two locations (Weslaco and Corpus Christi, TX) investigated feeding-injury of the verde plant bug to a range of cotton boll age classes defined by boll diameter and accumulated degree-days (anthesis to the time of infesting) for first-position cotton bolls infested with the plant bugs. The most detrimental damage to younger cotton holls from verde plant bug feeding was boll abscission. Cotton bolls <04 accumulating daily degree-days (ACDD), or a boll diameter of 1.3 cm were subject to 60-70% higher boll abscission when compared with the noninfested controls. Significantly higher boll abscission occurred from verde plant bug injured bolls compared with the controls up to 162 ACDD or a mean boll diameter 2.0 cm. Cotton seed weights were significantly reduced up to 179 ACDD or a boll diameter of 2.0 cm at Weslaco in 2009, and up to 317 ACDD or boll diameter 2.6 cm for Weslaco in 2010 when compared with the noninfested controls. Lint weight per cotton boll for infested and noninfested bolls was significantly reduced up to 262 ACDD or boll diameter 2.5 for Corpus Christi in 2010 and up to 288 ACCD or boll diameter 2.6 cm for Weslaco, TX, in 2010. Damage ratings (dependant variable) regressed against infested and noninfested seed-cotton weights showed that in every instance, the infested cotton bolls had a strong and significant relationship with damage ratings for all age classes of bolls. Damage ratings for the infested cotton bolls that did not abscise by harvest showed visual signs of verde plant bug feeding injury and the subsequent development ofboll rot; however, these two forms of injury causing lint and seed mass loss are hard to differentiate from open or boll-locked cotton bolls. Based on the results of both lint and seed loss over 2 yr and four studies cotton bolls should be protected up to approximately 300 ACDD or a boll diameter of 2.5 cm. This equilibrates to bolls that are 12-14 d of age dependent upon daily maximum and minimum temperatures. PMID:23448031

Armstrong, J Scott; Brewer, Michael J; Parker, Roy D; Adamczyk, J J

2013-02-01

371

Comparison of emission from the water column and wetland plants at the Berry's Creek estuary, Hackensack Meadowlands, New Jersey.  

NASA Astrophysics Data System (ADS)

Berry's Creek is a tidal tributary to the Hackensack River, and was historically subjected to discharges of mercury from the Ventron-Velsicol mercury processing site. The emission of mercury from this site to the atmosphere can follow three pathways: 1) emission from the water column, 2) transpiration through plants, and 3) emission from exposed wetland sediments. In this poster, we present a comparison of the first two emission pathways which have been studied at this site to date. Emission of mercury from the water column mercury to the atmosphere results from complex biogeochemical reactions between photoreactive dissolved organic carbon, ultraviolet light, and dissolved aqueous mercury. Emission rates measured using a dynamic flux chamber ranged from -0.64 to 34 ng/m2-h. Solar radiation and DOC spectral slope appear to exert the strongest control on mercury emission, with solar radiation alone accounting for up to 98% of the diel changes in mercury emission. Emission of mercury from plants appears to be a complex process that includes emission of mercury along with water vapor during transpiration as well as deposition to plant surfaces. Emission rates from Phragmites australis leaves ranged from -0.64 to 0.17 ng/m2-h. Annual and diel cycles are considered in an estimation of the magnitude of total mercury emitted through each pathway over the duration of 1 year.

Peters, S.; Wollenberg, J.; Bubb, M.

2008-12-01

372

A study of nuclear plant heat rate optimization using nonlinear artificial intelligence and linear statistical analysis models  

NASA Astrophysics Data System (ADS)

The emphasis of this dissertation is on developing methods by which a combination of multivariate analysis techniques (MAT) and artificial intelligence (AI) procedures can be adapted to on-line, real time monitoring systems for improving nuclear plant thermal efficiency. Present-day first principle models involve performing a heat balance of plant systems and the reactor coolant system. Typical variables involved in the plant data acquisition system usually number one-to-two thousand. The goal of the current work is twofold. First, simulate the heat rate with MAT and AI computer models. The second objective is to selectively reduce the number of predictors to only the most important variables, induce small perturbations around normal operating levels, and evaluate changes in the magnitude of plant efficiency. It is anticipated that making small changes will improve the thermal efficiency of the plant and lead to supplementary cost savings. Conclusions of this report are several. A sensitivity analysis showed the reduction of input variables by dimensionality reduction, i.e., principal component analysis or factor analysis, removes valuable information. Predictors can simply be eliminated from the input space, but dimensionality reduction of the input matrix is not an alternative option. However, perturbation modeling does require data to be standardized and collinear variables removed. Filtering of input data is not recommended except to remove outliers. It's ascertained that perturbation or sensitivity analysis differs from prediction modeling in that two additional requirements are necessary besides the criterion prediction. One is the magnitude of the criterion result given an input perturbation, and second, is the directionality of the model. Directionality is defined as the positive or negative movement of the heat rate (criterion) given a predetermined increase/decrease in predictor value, or input perturbation. While the criterion prediction is still important, it is directionality that determines whether a model is capturing proper changes in system process information. Final results showed that although the secondary-side of a nuclear plant might meet thermodynamic conditions for a steady-flow system, temporal information is needed by the model in order to capture system process information. Modeling of the data is governed by quasi-static range theory, which states data must be closely spaced (in time) and prior temporal information is necessary. The conclusion reached is the perturbation model of a nuclear plant is a time-dependent, dynamic system; all indications as of date show it is also nonlinear. Hence a time-dependent nonlinear modeling method, such as a neural network with time delayed inputs, is needed for sensitivity modeling.

Irvine, Claude A.

373

Modeled dosage-response relationship on the net photosynthetic rate for the sensitivity to acid rain of 21 plant species.  

PubMed

This study investigated the sensitivity of plant species to acid rain based on the modeled dosage-response relationship on the net photosynthetic rate (P (N)) of 21 types of plant species, subjected to the exposure of simulated acid rain (SAR) for 5 times during a period of 50 days. Variable responses of P (N) to SAR occurred depending on the type of plant. A majority (13 species) of the dosage-response relationship could be described by an S-shaped curve and be fitted with the Boltzmann model. Model fitting allowed quantitative evaluation of the dosage-response relationship and an accurate estimation of the EC(10), termed as the pH of the acid rain resulting in a P (N) 10 % lower than the reference value. The top 9 species (Camellia sasanqua, Cinnamomum camphora, etc. EC(10) ? 3.0) are highly endurable to very acid rain. The rare, relict plant Metasequoia glyptostroboides was the most sensitive species (EC(10) = 5.1) recommended for protection. PMID:22562418

Deng, Shihuai; Gou, Shuzhen; Sun, Baiye; Lv, Wenlin; Li, Yuanwei; Peng, Hong; Xiao, Hong; Yang, Gang; Wang, Yingjun

2012-05-08

374

Plants  

NSDL National Science Digital Library

How does a plant grow? Fill this out as you look through the websites Worksheet First watch the video Plant Life Cycle Video Then click around on this website and learn all about plants LIfe Cycle of Plants Next review and play with parts of a plant learning parts of the plant Next watch the video and learn What does it need to grow? Then learn how to Growing a plant Once you are finished come to my desk to plant your own flower! ...

Barron, Anne

2011-04-21

375

Common-cause fault rates for valves. Estimates based on licensee event reports at US commercial nuclear power plants, 1976-1980. [PWR; BWR  

Microsoft Academic Search

This report presents estimates of common-cause fault rates and related quantities, based on Licensee Event Reports for valves in nuclear reactors. The Licensee Event Report data base is described. For estimating rates, the binomial failure-rate model is used, extended to allow for the substantial observed plant-to-plant variability, and for shocks that by their nature make all the valves in a

J. A. Steverson; C. L. Atwood

1983-01-01

376

Studies of Shock/Shock Interaction on Smooth and Transpiration-Cooled Hemispherical Nosetips in Hypersonic Flow.  

National Technical Information Service (NTIS)

A program of experimental research and analysis was conducted to examine the heat transfer and pressure distributions in regions of shock/shock interaction over smooth and transpiration-cooled hemispherical noseshapes. The objective of this investigation ...

M. S. Holden K. M. Rodriguez

1992-01-01

377

Transmission rates and adaptive evolution of pathogens in sympatric heterogeneous plant populations.  

PubMed Central

Diversification in agricultural cropping patterns is widely practised to delay the build-up of virulent races that can overcome host resistance in pathogen populations. This can lead to balanced polymorphism, but the long-term consequences of this strategy for the evolution of crop pathogen populations are still unclear. The widespread occurrence of sibling species and reproductively isolated sub-species among fungal and oomycete plant pathogens suggests that evolutionary divergence is common. This paper develops a mathematical model of host-pathogen interactions using a simple framework of two hosts to analyse the influences of sympatric host heterogeneity on the long-term evolutionary behaviour of plant pathogens. Using adaptive dynamics, which assumes that sequential mutations induce small changes in pathogen fitness, we show that evolutionary outcomes strongly depend on the shape of the trade-off curve between pathogen transmission on sympatric hosts. In particular, we determine the conditions under which the evolutionary branching of a monomorphic into a dimorphic population occurs, as well as the conditions that lead to the evolution of specialist (single host range) or generalist (multiple host range) pathogen populations.

Gudelj, I; van den Bosch, F; Gilligan, C A

2004-01-01

378

Alternative perspective on the control of transpiration by radiation  

PubMed Central

Stomatal responses to light are important determinants for plant water use efficiency and for general circulation models, but a mechanistic understanding of these responses remains elusive. A recent study [Pieruschka R, Huber G, Berry JA (2010) Proc Natl Acad Sci USA 107:13372–13377] concluded that stomata respond to total absorbed radiation rather than red and blue light as previously thought. We tested this idea by reexamining stomatal responses to red and blue light and to IR radiation. We show that responses to red and blue light are not consistent with a response to total absorbed radiation and that apparent stomatal responses to IR radiation are explainable as experimental artifacts. In addition, our data and analysis provide a method for accurately determining the internal temperature of a leaf.

Mott, Keith A.; Peak, David

2011-01-01

379

Nitrite feeding of leaf discs induces inhibition of photosynthesis and transpiration similar to NO sub 2 exposure  

SciTech Connect

Exposure of plants to acute concentrations of NO{sub 2} within the atmosphere induces inhibition of photosynthesis and transpiration rapidly. Later the leaf tissue shows a water-logging' visible injury pattern, indication a loss of cellular water. It is believed that this occurs because of the formation of nitrite and nitrate within the cell wall region by the hydration of NO{sub 2}. If the concentration of these nitrogen compounds is high, the cells would be unable to metabolize them. Their accumulation, especially of NO{sub 2}, would inhibit photosynthesis and alter normal osmotic relationships. This sequence can be demonstrated by the use of chamber holding a cut leaf disc in which the edges can be fed a variety of compounds. When nitrite is fed to the leaf only at low pH (ca. 4), the symptoms observed after about 60 minutes are very similar to those seen with NO{sub 2} exposure. The calculation of concentrations indicates that the above hypothesis for acute NO{sub 2} toxicity is, for the most part, correct.

Heath, R.L.; Miller, R. (Univ. of California, Riverside (United States))

1991-05-01

380

Numerical analysis of material response for transpiration-cooled thermal protection system  

Microsoft Academic Search

The material response of a two-dimensional transpiration-cooled system consisting of a porous matrix and a coolant gas in a convective\\/radiative heating environment is numerically analyzed. The fundamental equations for coolant and solid matrix are solved simultaneously, including the effects of radiative transfer and volumetric heat transfer between solid and coolant, using a strongly implicit procedure and modified differential quadrature. Cooling

T. Kurotaki; H. Kubota

1984-01-01

381

Analysis of the effect of EC and potential transpiration on vegetative growth of tomato  

Microsoft Academic Search

This paper analyses the response of vegetative growth of greenhouse tomato to both root-zone salinity and shoot-environment (potential transpiration), with the purpose of explaining the observed lack of effect on dry matter yield. A reference salinity (EC) of 2dSm?1 was compared in three experiments with, respectively, 6.5, 8 and 9.5dSm?1. Another experiment investigated specific effects of sodium chloride, by comparing

Ya Ling Li; Cecilia Stanghellini

2001-01-01

382

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

USGS Publications Warehouse

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 (Quercus macrocarpa) savanna woodland encroached by elms (Ulmus americana), and in an adjacent restored savanna after thinning to remove elms, during summer 2004. Savanna oaks had greater mean daily Js (35.9 L dm-2 day-1) than woodland oaks (20.7 L dm-2 day-1) and elms (12.4 L dm-2 day-1). The response of Js to vapor pressure deficit (D) was unexpectedly weak, although oaks in both stands showed negative correlation between daily Js and D for D > 0.4 kPa. An earlier daily peak in Js in the elm trees showed a possible advantage for water uptake. As anticipated, the woodland's stand transpiration was greater (1.23 mm day-1) than the savanna's (0.35 mm day-1), yet the savanna achieved 30% of the woodland's transpiration with only 11% of its sapwood area. The difference in transpiration influenced water table depths, which were 2 m in the savanna and 6.5 m in the woodland. Regionally, row-crop agriculture has increased groundwater recharge and raised water tables, providing surplus water that perhaps facilitated elm encroachment. This has implications for restoration of savanna remnants. If achieving a savanna ecohydrology is an aim of restoration, then restoration strategies may require buffers, or targeting of large or hydrologically isolated remnants. ?? 2007.

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

2007-01-01

383

Analysis of plant function as bio-thermal-conditioner using Pothos ( Epipremnum aureum)  

Microsoft Academic Search

Plants absorb carbon dioxide by photosynthesis using solar energy and use thermal energy in the atmosphere by transpiration. Paying attention to the excellent functions that plants perform, we have measured the daily variation of the temperature and humidity on plant circumference of an individual level using Pothos (Epipremnum aureum), and have investigated the thermal conditioning effect of the plant irradiated

Tadashi Nakazato; Terumi Inagaki

384

Difference of stand-scale transpiration between ridge and riparian area in a watershed with Japanese cypress plantation  

NASA Astrophysics Data System (ADS)

Several different methods to assess water use are available, and the sap flux measurement technique is one of the most promising methods, especially in monotonous watershed. Previously, three spatial levels of scaling have been used to obtain bottom-up transpiration estimates based on the sap flux technique: from within-tree to tree, from tree to stand, and from stand to watershed or landscape. Although there are considerable variations that must be taken into account at each step, few studies have examined plot-to-plot variability of stand-scale transpirations. To design optimum sampling method to accurately estimate transpiration at the watershed-scale, it is indispensable to understand heterogeneity of stand-scale transpiration in a forested watershed and the factors determining the heterogeneity. This study was undertaken to clarify differences of stand-scale transpirations within a watershed and the factors determining the differences. To this aim, we conducted sap flux-based transpiration estimates in two plots such as a lower riparian (RZ) and an upper ridge (UZ) zone in a watershed with Japanese cypress plantation, Kyushu, Japan in two years. Tree height and diameter of breast height (DBH) were lager in RZ than those of UZ. The stand sapwood area (As) was lager in RZ than UZ (21.9 cm2h a-1, 16.8 cm2ha-1, respectively). Stand mean sap flux (Js) in RZ was almost same as that of UZ when relatively lower Js, while, Js in RZ was higher than that of UZ when relatively higher Js (i.e., bright days in summer season). Consequently, daily stand-scale transpiration (E), which is the multiple of As and Js, differed by two times between RZ and UZ in summer season. This study found significant heterogeneity of stand-scale transpiration within the watershed and that the differences could be caused by two aspects such as stand structure and sap flux velocity.

Kume, T.; Tsuruta, K.; Komatsu, H.; Shinohara, Y.; Otsuki, K.

2011-12-01

385

Modeling canopy transpiration using time series analysis: A case study illustrating the effect of soil moisture deficit on Pinus taeda  

Microsoft Academic Search

Bulk sap flow measurements are widely used to assess and model the hydrological process of canopy transpiration (Ec); however, common analysis techniques of these data do not identify and\\/or incorporate time lag effects, multiple variables affecting canopy transpiration at different temporal scales or thresholds, and interactions of environmental variables. Here, we describe how autoregressive-integrated-moving average (ARIMA) time series models can

Chelcy R. Ford; Carol E. Goranson; Robert J. Mitchell; Rodney E. Will; Robert O. Teskey

2005-01-01

386

Survey of U.S. Costs and Water Rates for Deslaination and Membrane Softening Plants.  

National Technical Information Service (NTIS)

The report is based ona survey by Leitner and Associates, Inc., of U.S. costs and water rates for utilities that use desalination and membrane softening. The report provides information of the following four processes: reverse osmosis for brackish/groundw...

1997-01-01

387

Component failure-rate data with potential applicability to a nuclear fuel reprocessing plant  

SciTech Connect

Approximately 1223 pieces of component failure-rate data, under 136 subject categories, have been compiled from published literature and computer searches of a number of data bases. Component selections were based on potential applicability to facilities for reprocessing spent nuclear fuels. The data will be useful in quantifying fault trees for probabilistic safety analyses and risk assessments.

Dexter, A.H.; Perkins, W.C.

1982-07-01

388

Stable isotope composition of water vapor as an indicator of transpiration fluxes from rice crops  

NASA Astrophysics Data System (ADS)

Measurements of the stable isotope composition (?2H and ?18O) of water vapor and associated micrometeorological parameters were made before and after full establishment of a rice crop in southeastern Australia. The aim of the experiment was to gain a better understanding of stable isotope variations of water vapor near the ground surface in response to local evaporation, local transpiration, regional scale vapor transport and the vertical stability of the atmospheric boundary layer. Vapor samples were collected at several heights within 9 m of the water surface during two separate sampling periods. The ?2H values of the water vapor ranged over more than 60‰, reflecting major rapid changes in regional air mass sources, as well as variations in the stability of the lowest 10 m of the atmosphere. The influence of tropical and higher-latitude air masses resulted in local vapor compositions which were relatively enriched and depleted, respectively, in heavy isotopes. Vertical gradients in heavy isotope abundances were very large during stable conditions (as much as ??2H = -27‰ from 0.8 to 8.4 m), as the result of mixing between transpired water and regional air vapor. Transpiration fluxes calculated from the water vapor ?2H gradient ranged from 5 to 7 mm d-1, which was in good agreement with one-dimensional aerodynamic energy budget calculations of daytime vapor fluxes.

Brunel, J. P.; Simpson, H. J.; Herczeg, A. L.; Whitehead, R.; Walker, G. R.

1992-05-01

389

Incorporating spatially explicit crown light competition into a model of canopy transpiration  

NASA Astrophysics Data System (ADS)

Stomatal conductance parameterized in a transpiration model has been shown to vary spatially for aspen ( Populus tremuloides) and alder (Alnus incana) growing along a moisture gradient. We hypothesized that competition for light within the canopy would explain some of this variation. Sap flux data was collected over 10 days in 2004, and 30 days in 2005 at a 1.5 ha site near the WLEF AmeriFlux tower in the Chequmegon National Forest near Park Falls, Wisconsin. We used inverse modeling with the Terrestrial Regional Ecosystem Exchange Simulator (TREES) to estimate values of GSref for individual trees. Competition data for individual aspen sampled for sap flux was collected in August 2006. The number, height, DBH, and location of all competitors within 5 meters of each flux tree were recorded. Preliminary geostatistical analysis indicates that the number of competitor trees varies spatially for aspen. We hypothesize that height and species specific crown characteristics of competitor trees will have a spatially variable affect on transpiration via light attenuation. Furthermore, a simple light competition term will be able to incorporate this variability into the TREES transpiration model.

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

2006-12-01

390

Stomatal Crypts Have Small Effects on Transpiration: A Numerical Model Analysis1  

PubMed Central

Stomata arranged in crypts with trichomes are commonly considered to be adaptations to aridity due to the additional diffusion resistance associated with this arrangement; however, information on the effect of crypts on gas exchange, relative to stomata, is sparse. In this study, three-dimensional Finite Element models of encrypted stomata were generated using commercial Computational Fluid Dynamics software. The models were based on crypt and stomatal architectural characteristics of the species Banksia ilicifolia, examined microscopically, and variations thereof. In leaves with open or partially closed stomata, crypts reduced transpiration by less than 15% compared with nonencrypted, superficially positioned stomata. A larger effect of crypts was found only in models with unrealistically high stomatal conductances. Trichomes inside the crypt had virtually no influence on transpiration. Crypt conductance varied with stomatal conductance, boundary layer conductance, and ambient relative humidity, as these factors modified the three-dimensional diffusion patterns inside crypts. It was concluded that it is unlikely that the primary function of crypts and crypt trichomes is to reduce transpiration.

Roth-Nebelsick, Anita; Hassiotou, Foteini; Veneklaas, Erik J.

2009-01-01

391

Temperature and Transpiration Resistances of Xanthium Leaves as Affected by Air Temperature, Humidity, and Wind Speed 1  

PubMed Central

Transpiration and temperatures of single, attached leaves of Xanthium strumarium L. were measured in high intensity white light (1.2 calories per square centimeter per minute on a surface normal to the radiation), with abundant water supply, at wind speeds of 90, 225, and 450 centimeters per second, and during exposure to moist and dry air. Partitioning of absorbed radiation between transpiration and convection was determined, and transpiration resistances were computed. Leaf resistances decreased with increasing temperature (down to a minimum of 0.36 seconds per centimeter). Silicone rubber replicas of leaf surfaces proved that the decrease was due to increased stomatal apertures. At constant air temperature, leaf resistances were higher in dry than in moist air with the result that transpiration varied less than would have been predicted on the basis of the water-vapor pressure difference between leaf and air. The dependence of stomatal conductance on temperature and moisture content of the air caused the following effects. At air temperatures below 35 C, average leaf temperatures were above air temperature by an amount dependent on wind velocity; increasing wind diminished transpiration. At air temperatures above 35 C, leaf temperatures were below air temperatures, and increasing wind markedly increased transpiration. Leaf temperatures equaled air temperature near 35 C at all wind speeds and in moist as well as in dry air.

Drake, B. G.; Raschke, K.; Salisbury, F. B.

1970-01-01

392

Electron flow to oxygen in higher plants and algae: rates and control of direct photoreduction (Mehler reaction) and rubisco oxygenase.  

PubMed

Linear electron transport in chloroplasts produces a number of reduced components associated with photosystem I (PS I) that may subsequently participate in reactions that reduce O2. The two primary reactions that have been extensively studied are: first, the direct reduction of O2 to superoxide by reduced donors associated with PS I (the Mehler reaction), and second, the rubisco oxygenase (ribulose 1,5-bisphosphate carboxylase oxygenase EC 4.1.1.39) reaction and associated peroxisomal and mitochondrial reactions of the photorespiratory pathway. This paper reviews a number of recent and past studies with higher plants, algae and cyanobacteria that have attempted to quantify O2 fluxes under various conditions and their contributions to a number of roles, including photon energy dissipation. In C3 and Crassulacean acid metabolism (CAM) plants, a Mehler O2 uptake reaction is unlikely to support a significant flow of electron transport (probably less than 10%). In addition, if it were present it would appear to scale with photosynthetic carbon oxidation cycle (PCO) and photosynthetic carbon reduction cycle (PCR) activity This is supported by studies with antisense tobacco plants with reduced rubisco at low and high temperatures and high light, as well as studies with potatoes, grapes and madrone during water stress. The lack of significant Mehler in these plants directly argues for a strong control of Mehler reaction in the absence of ATP consumption by the PCR and PCO cycles. The difference between C3 and C4 plants is primarily that the level of light-dependent O2 uptake is generally much lower in C4 plants and is relatively insensitive to the external CO2 concentration. Such a major difference is readily attributed to the operation of the C4 CO2 concentrating mechanism. Algae show a range of light-dependent O2 uptake rates, similar to C4 plants. As in C4 plants, the O2 uptake appears to be largely insensitive to CO2, even in species that lack a CO2 concentrating mechanism and under conditions that are clearly limiting with respect to inorganic carbon supply. A part explanation for this could be that many algal rubsicos have considerably different oxygenase kinetic properties and exhibit far less oxygenase activity in air. This would lead to the conclusion that perhaps a greater proportion of the observed O2 uptake may be due to a Mehler reaction and less to rubisco, compared with C3 plants. In contrast to algae and higher plants, cyanobacteria appear to have a high capacity for Mehler O2 uptake, which appears to be not well coupled or limited by ATP consumption. It is likely that in all higher plants and algae, which have a well-developed non-photochemical quenching mechanism, non-radiative energy dissipation is the major mechanism for dissipating excess photons absorbed by the light-harvesting complexes under stressful conditions. However, for cyanobacteria, with a lack of significant non-photochemical quenching, the situation may well be different. PMID:11127997

Badger, M R; von Caemmerer, S; Ruuska, S; Nakano, H

2000-10-29

393

Effect of various irradiation treatments of plant protoplasts on the transformation rates after direct gene transfer  

Microsoft Academic Search

In P. hybrida and B. nigra an enhancement of transformation rates (direct gene transfer) of about six to seven-fold was obtained after irradiation of protoplasts with 12.5 Gy (X-ray). The effect of protoplast irradiation was similar in experiments where protoplasts were irradiated 1h before transformation (X-ray\\/DNA) or 1h after completion of the transformation procedure (DNA\\/X-ray). Increased X-ray doses up to

F. Köhler; I. Benediktsson; G. Cardon; C. S. Andreo; O. Schieder

1990-01-01

394

Effects of plant density on the survival rate of cabbage pests  

Microsoft Academic Search

The population density of herbivores depends on the spatial scale as well as the temporal scale. In a small-scale, short-term\\u000a experiment, the number of individuals entering from the surrounding area will be most influential in determining the herbivore\\u000a density. In large-scale, long-term experiments, however, the density of herbivores will rather be influenced by the survival\\u000a rate of individuals inside the

Kohji Yamamura; Eizi Yano

1999-01-01

395

Environmental contamination and external radiation dose rates from radionuclides released from the Fukushima Nuclear Power Plant.  

PubMed

To evaluate the environmental contamination and contributory external exposure after the accident at the Fukushima Nuclear Power Plant (FNPP), the concentrations of artificial radionuclides in soil samples from each area were analysed by gamma spectrometry. Six artificial radionuclides ((131)I, (134)Cs, (137)Cs, (129m)Te, (95)Nb and (136)Cs) were detected in soil samples around FNPP. Calculated external effective doses from artificial radionuclide contamination in soil samples around FNPP were 1.9-2.9 ?Sv h(-1) (8.7-17.8 mSv y(-1)) in Fukushima city on 22 March 2011. After several months, these calculated external effective doses were 0.25-0.88 ?Sv h(-1) (2.2-7.6 mSv y(-1)) in Fukushima city on 29 June 2011. The present study revealed that the detected artificial radionuclides around FNPP mainly shifted to long-lived radionuclides such as radioactive caesium ((134)Cs and (137)Cs) even though current levels are decreasing gradually due to the decay of short-lived radionuclides such as (131)I, (129m)Te, (95)Nb and (136)Cs. Thus, radiation exposure potency still exists even though the national efforts are ongoing for reducing the annual exposure dose closer to 1 mSv, the public dose limit. Long-term environmental monitoring around FNPP contributes to radiation safety, with a reduction in unnecessary exposure to the residents. PMID:22504310

Taira, Yasuyuki; Hayashida, Naomi; Yamashita, Shunichi; Kudo, Takashi; Matsuda, Naoki; Takahashi, Jumpei; Gutevitc, Alexander; Kazlovsky, Alexander; Takamura, Noboru

2012-04-13

396

Whole-photosynthesis and transpiration in field-grown papaya plants  

Technology Transfer Automated Retrieval System (TEKTRAN)

Papaya (Carica papaya L.) is a principal horticultural crop of tropical and subtropical regions. Knowledge of papaya response to environmental factors provides a scientific basis to develop management strategies to optimize fruit yield and quality. In papaya, the photosynthetic capacity also influ...

397

An Interpretation of Some Whole Plant Water Transport Phenomena  

PubMed Central

A treatment of water flow into and through plants to the evaporating surface of the leaves is presented. The model is driven by evaporation from the cell wall matrix of the leaves. The adsorptive and pressure components of the cell wall matric potential are analyzed and the continuity between the pressure component and the liquid tension in the xylem established. Continuity of these potential components allows linking of a root transport function, driven by the tension in the xylem, to the leaf water potential. The root component of the overall model allows for the solvent-solute interactions characteristic of a membrane-bound system and discussion of the interactions of environmental variables such as root temperature and soil water potentials. A partition function is developed from data in the literature which describes how water absorbed by the plant might be divided between transpiration and leaf growth over a range of leaf water potentials. Relationships between the overall system conductance and the conductance coefficients of the various plant parts (roots, xylem, leaf matrix) are established and the influence of each of these discussed. The whole plant flow model coupled to the partition function is used to simulate several possible relationships between leaf water potential and transpiration rate. The effects of changing some of the partition function coefficients, as well as the root medium water potential on these simulations is illustrated. In addition to the general usefulness of the model and its ability to describe a wide range of situations, we conclude that the relationships used, dealing with bulk fluid flow, diffusion, and solute transport, are adequate to describe the system and that analogically based theoretical systems, such as the Ohm's law analogy, probably ought to be abandoned for this purpose.

Fiscus, Edwin L.; Klute, Arnold; Kaufmann, Merrill R.

1983-01-01

398

Conversion rates in power plant plumes based on filter pack data. Part I. Coal-fired Cumberland plume  

SciTech Connect

The TVA Cumberland Steam Plant plume was monitored during the August 1978 Tennessee Plume Study of Project STATE. Samples were obtained by employing a triple screen high-volume assembly which contained: (1) a quartz filter for collecting particulate SO/sub 4//sup 2 -/, NO/sub 3//sup -/ and NH/sub 4//sup +/, (2) two NaCl-impregnated cellulose filters for collecting gaseous nitrate, and (3) two K/sub 2/CO/sub 3/-impregnated cellulose filters for collecting SO/sub 2/. Formation rates of sulfate and nitrate in the atmosphere were calculated by using total sulfur as a conservative tracer. Conversion of SO/sub 2/ to SO/sub 4//sup 2 -/ varied from approx. 0.1 to 0.8% h/sup -1/ during night and early morning hours; late morning and afternoon rates ranged from approx. 1 to 4% h/sup -1/. Rate of formation of NO/sub 3//sup -/ from NO was approx. 0.1 to 3% h/sup -1/ and approx. 3 to 12% h/sup -1/ for similar time periods. Particulate NH/sub 4//sup +/ concentrations generally increased with plume age, but rates of formation varied widely. Mole ratios of NH/sub 4//sup +//SO/sub 4//sup 2 -/ fell within 1 to 3.

Forrest, J; Garber, R W; Newman, L

1980-01-01

399

Phenological changes in rate of respiration and annual carbon balance in a perennial herbaceous plant, Primula sieboldii.  

PubMed

Primula sieboldii E. Morren is a clonal herbaceous species with a short foliar period from spring to early summer. We have studied the temperature-dependence of the rate of respiration at the whole-ramet level throughout the phenological stages of P. sieboldii to reveal its photosynthate-utilization strategy. P. sieboldii ramets were grown in a chamber enabling simulation of seasonal changes in temperature. Rates of respiration were measured at three phenological stages--the foliar period, the before-chilling defoliated (BCD) period, and the after--chilling defoliated (ACD) period. In the foliar period the rate of respiration, on a biomass basis at 20 degrees C (R (20)), of the above-ground plant parts was 2.5 times that of the below-ground parts. The R (20) of the below-ground parts in the foliar period was 6.5 times that in the BCD period and 1.6 times that in the ACD period. Estimation of the ramet carbon balance under these growth conditions showed that ramets respired 87% of total photosynthate production during the experimental period (8.5 months). Respiratory consumption in the foliar period accounted for 70% of the yearly total, whereas 24 and 6% were consumed in the BCD and ACD periods, respectively. An extremely low rate of respiration during the long defoliated period led to a positive net annual carbon balance for P. sieboldii ramets. PMID:17492255

Noda, Hibiki; Muraoka, Hiroyuki; Tang, Yanhong; Washitani, Izumi

2007-02-15

400

Estimation of hydrogen sulfide emission rates at several wastewater treatment plants through experimental concentration measurements and dispersion modeling.  

PubMed

The management and operation of wastewater treatment plants (WWTP) usually involve the release into the atmosphere of malodorous substances with the potential to reduce the quality of life of people living nearby. In this type of facility, anaerobic degradation processes contribute to the generation of hydrogen sulfide (H2S), often at quite high concentrations; thus, the presence of this chemical compound in the atmosphere can be a good indicator of the occurrence and intensity of the olfactory impact in a specific area. The present paper describes the experimental and modelling work being carried out by CEAM-UMH in the surroundings of several wastewater treatment plants located in the Valencia Autonomous Community (Spain). This work has permitted the estimation of H2S emission rates at different WWTPs under different environmental and operating conditions. Our methodological approach for analyzing and describing the most relevant aspects of the olfactory impact consisted of several experimental campaigns involving intensive field measurements using passive samplers in the vicinity of several WWTPs, in combination with numerical simulation results from a diagnostic dispersion model. A meteorological tower at each WWTP provided the input values for the dispersion code, ensuring a good fit of the advective component and therefore more confidence in the modelled concentration field in response to environmental conditions. Then, comparisons between simulated and experimental H2S concentrations yielded estimates of the global emission rate for this substance at several WWTPs at different time periods. The results obtained show a certain degree of temporal and spatial (between-plant) variability (possibly due to both operational and environmental conditions). Nevertheless, and more importantly, the results show a high degree of uniformity in the estimates, which consistently stay within the same order of magnitude. PMID:22866577

Llavador Colomer, Fernando; Espinós Morató, Héctor; Mantilla Iglesias, Enrique

2012-07-01

401

Intrinsic rate of population increase of the spider mite Tetranychus urticae on the ornamental crop gerbera: intraspecific variation in host plant and herbivore  

Microsoft Academic Search

Eight cultivars of the ornamental crop Gerbera jamesonii Bolus (Asteraceae) were compared in host plant suitability for the two spotted spider mite Tetranychus urticae Koch (Acarina: Tetranychidae). This was done by determining the intrinsic rate of population increase, rm, of spider mites on leaf discs of plants from each of the cultivars. Large differences in rm values were found, ranging

O. E. Krips; A. Witul; P. E. L. Willems; M. Dicke

1998-01-01

402

Solar Ultraviolet-B Radiation Affects Seedling Emergence, DNA Integrity, Plant Morphology, Growth Rate, and Attractiveness to Herbivore Insects in Datura ferox.  

PubMed Central

To study functional relationships between the effects of solar ultraviolet-B radiation (UV-B) on different aspects of the physiology of a wild plant, we carried out exclusion experiments in the field with the summer annual Datura ferox L. Solar UV-B incident over Buenos Aires reduced daytime seedling emergence, inhibited stem elongation and leaf expansion, and tended to reduce biomass accumulation during early growth. However, UV-B had no effect on calculated net assimilation rate. Using a monoclonal antibody specific to the cyclobutane-pyrimidine dimer (CPD), we found that plants receiving full sunlight had more CPDs per unit of DNA than plants shielded from solar UV-B, but the positive correlation between UV-B and CPD burden tended to level off at high (near solar) UV-B levels. At our field site, Datura plants were consumed by leaf beetles (Coleoptera), and the proportion of plants attacked by insects declined with the amount of UV-B received during growth. Field experiments showed that plant exposure to solar UV-B reduced the likelihood of leaf beetle attack by one-half. Our results highlight the complexities associated with scaling plant responses to solar UV-B, because they show: (a) a lack of correspondence between UV-B effects on net assimilation rate and whole-plant growth rate, (b) nonlinear UV-B dose-response curves, and (c) UV-B effects of plant attractiveness to natural herbivores.

Ballare, C. L.; Scopel, A. L.; Stapleton, A. E.; Yanovsky, M. J.

1996-01-01

403

Evolution of leaf-form in land plants linked to atmospheric CO2 decline in the Late Palaeozoic era.  

PubMed

The widespread appearance of megaphyll leaves, with their branched veins and planate form, did not occur until the close of the Devonian period at about 360 Myr ago. This happened about 40 Myr after simple leafless vascular plants first colonized the land in the Late Silurian/Early Devonian, but the reason for the slow emergence of this common feature of present-day plants is presently unresolved. Here we show, in a series of quantitative analyses using fossil leaf characters and biophysical principles, that the delay was causally linked with a 90% drop in atmospheric pCO2 during the Late Palaeozoic era. In contrast to simulations for a typical Early Devonian land plant, possessing few stomata on leafless stems, those for a planate leaf with the same stomatal characteristics indicate that it would have suffered lethal overheating, because of greater interception of solar energy and low transpiration. When planate leaves first appeared in the Late Devonian and subsequently diversified in the Carboniferous period, they possessed substantially higher stomatal densities. This observation is consistent with the effects of the pCO2 on stomatal development and suggests that the evolution of planate leaves could only have occurred after an increase in stomatal density, allowing higher transpiration rates that were sufficient to maintain cool and viable leaf temperatures. PMID:11268207

Beerling, D J; Osborne, C P; Chaloner, W G

2001-03-15

404

Influence of low air humidity and low root temperature on water uptake, growth and aquaporin expression in rice plants.  

PubMed

The effects of low air humidity and low root temperature (LRT) on water uptake, growth and aquaporin gene expression were investigated in rice plants. The daily transpiration of the plants grown at low humidity was 1.5- to 2-fold higher than that at high humidity. LRT at 13°C reduced transpiration, and the extent was larger at lower humidity. LRT also reduced total dry matter production and leaf area expansion, and the extent was again larger at lower humidity. These observations suggest that the suppression of plant growth by LRT is associated with water stress due to decreased water uptake ability of the root. On the other hand, the net assimilation rate was not affected by low humidity and LRT, and water use efficiency was larger for LRT. We found that low humidity induced coordinated up-regulation of many PIP and TIP aquaporin genes in both the leaves and the roots. Expression levels of two root-specific aquaporin genes, OsPIP2;4 and OsPIP2;5, were increased significantly after 6 and 13 d of LRT exposure. Taken together, we discuss the possibility that aquaporins are part of an integrated response of this crop to low air humidity and LRT. PMID:22685088

Kuwagata, Tsuneo; Ishikawa-Sakurai, Junko; Hayashi, Hidehiro; Nagasuga, Kiyoshi; Fukushi, Keiko; Ahamed, Arifa; Takasugi, Katsuko; Katsuhara, Maki; Murai-Hatano, Mari

2012-06-08

405

Unraveling the Effects of Plant Hydraulics on Stomatal Closure during Water Stress in Walnut  

PubMed Central

The objectives of the study were to identify the relevant hydraulic parameters associated with stomatal regulation during water stress and to test the hypothesis of a stomatal control of xylem embolism in walnut (Juglans regia × nigra) trees. The hydraulic characteristics of the sap pathway were experimentally altered with different methods to alter plant transpiration (Eplant) and stomatal conductance (gs). Potted trees were exposed to a soil water depletion to alter soil water potential (?soil), soil resistance (Rsoil), and root hydraulic resistances (Rroot). Soil temperature was changed to alter Rroot alone. Embolism was created in the trunk to increase shoot resistance (Rshoot). Stomata closed in response to these stresses with the effect of maintaining the water pressure in the leaf rachis xylem (Prachis) above ?1.4 MPa and the leaf water potential (?leaf) above ?1.6 MPa. The same dependence of Eplant and gs on Prachis or ?leaf was always observed. This suggested that stomata were not responding to changes in ?soil, Rsoil, Rroot, or Rshoot per se but rather to their impact on Prachis and/or ?leaf. Leaf rachis was the most vulnerable organ, with a threshold Prachis for embolism induction of ?1.4 MPa. The minimum ?leaf values corresponded to leaf turgor loss point. This suggested that stomata are responding to leaf water status as determined by transpiration rate and plant hydraulics and that Prachis might be the physiological parameter regulated by stomatal closure during water stress, which would have the effect of preventing extensive developments of cavitation during water stress.

Cochard, Herve; Coll, Lluis; Le Roux, Xavier; Ameglio, Thierry

2002-01-01

406

Participation of Plant Hormones in Growth Resumption of Wheat Shoots Following Short-Term NaCl Treatment  

Microsoft Academic Search

The effects of sodium-chloride salinity on the leaf elongation rate, transpiration rate, cell sap osmolality, and phytohormone\\u000a content in 7-day-old shoots of durum wheat (Triticum durum L.) were studied. Leaf growth was suppressed under the salinity stress and resumed 1 h after NaCl removal. The resumption\\u000a of leaf growth coincided with a decrease in the transpiration rate due to the

G. R. Akhiyarova; I. B. Sabirzhanova; D. S. Veselov; V. Frike

2005-01-01

407

Plant senescence cues entry into diapause in the gall fly Eurosta solidaginis: resulting metabolic depression is critical for water conservation.  

PubMed

Mechanisms and possible cues for seasonal increases in desiccation resistance in larvae of the goldenrod gall fly Eurosta solidaginis, were examined before and after natural and premature plant senescence, or after being removed from their gall and placed in either 100, 95 or 75% relative humidity (RH). Rates of water loss were 8.6-fold lower, averaging 0.7+/-0.2 microg mm(-2) h(-1), in larvae from senescent gall tissue and after all RH treatments than in control larvae from pre-senescent plants. Enhanced desiccation resistance occurred quickly, within 3 days of removal from their gall. Contrary to most previous reports, a large majority of the increased desiccation resistance (approximately 85%) was due to reduced respiratory transpiration with the remainder being the result of a lowered cuticular permeability. Rates of cuticular water loss were reduced by the presence of a vapor pressure gradient between the larval hemolymph and environmental water vapor and were probably due to increases in cuticular lipids and/or production of the cryoprotectant glycerol. Metabolic rate was reduced by over fourfold, averaging 0.07+/-0.01 microl CO2 g(-1) h(-1), in larvae from senescent gall tissue and all RH treatments compared to larvae from pre-senescent plants. The magnitude of the reduction in metabolic rates indicated that these larvae had entered diapause. In addition, larvae entered diapause in response to removal from, or degeneration of, the gall tissue they feed, on rather than seasonal changes in temperature or photoperiod. The low metabolic rates of the diapausing larvae probably allowed them to dramatically reduce their respiratory transpiration and total rate of water loss compared with non-diapausing controls. Thus, diapause, with its associated lowered metabolic rate, may be essential for conserving water in overwintering temperate insects, which may be dormant for six or more months of the year. PMID:16339864

Williams, Jason B; Lee, Richard E

2005-12-01

408

A Tolerant Behavior in Salt-Sensitive Tomato Plants can be Mimicked by Chemical Stimuli  

PubMed Central

Lycopersicon esculentum plants exhibit increased salt stress tolerance following treatment with adipic acid monoethylester and 1,3-diaminepropane (DAAME), known as an inducer of resistance against biotic stress in tomato and pepper. For an efficient water and nutrient uptake, plants should adapt their water potential to compensate a decrease in water soil potential produced by salt stress. DAAME-treated plants showed a faster and stronger water potential reduction and an enhanced proline accumulation. Salinity-induced oxidative stress was also ameliorated by DAAME treatments. Oxidative membrane damage and ethylene emission were both reduced in DAAME-treated plants. This effect is probably a consequence of an increase of both non-enzymatic antioxidant activity as well as peroxidase activity. DAAME-mediated tolerance resulted in an unaltered photosynthetic rate and a stimulation of the decrease in transpiration under stress conditions without a cost in growth due to salt stress. The reduction in transpiration rate was concomitant with a reduction in phytotoxic Na+ and Cl? accumulation under saline stress. Interestingly, the ABA deficient tomato mutant sitiens was insensitive to DAAME-induced tolerance following NaCl stress exposure. Additionally, DAAME treatments increased the ABA content of leaves, therefore, an intact ABA signalling pathway seems to be important to express DAAME-induced salt tolerance. Here, we show a possibility of enhance tomato stress tolerance by chemical induction of the major plant defences against salt stress. DAAME-induced tolerance against salt stress could be complementary to or share elements with induced resistance against biotic stress. This might be the reason for the observed wide spectrum of effectiveness of this compound.

Flors, Victor; Paradis, Mercedes; Garcia-Andrade, Javier; Cerezo, Miguel; Gonzalez-Bosch, Carmen

2007-01-01

409

Root features related to plant growth and nutrient removal of 35 wetland plants.  

PubMed

Morphological, structural, and eco-physiological features of roots, nutrient removal, and correlation between the indices were comparatively studied for 35 emergent wetland plants in small-scale wetlands for further investigation into the hypothesis of two types of wetland plant roots (Chen et al., 2004). Significant differences in root morphological, structural, and eco-physiological features were found among the 35 species. They were divided into two types: fibrous-root plants and thick-root plants. The fibrous-root plants had most or all roots of diameter (D) ? 1 mm. Roots of D > 1 mm also had many fine and long lateral roots of D ? 1 mm. The roots of these plants were long and had a thin epidermis and a low degree of lignification. The roots of the thick-root plants were almost all thicker than 1 mm, and generally had no further fine lateral roots. The roots were short, smooth, and fleshy, and had a thick epidermis. Root porosity of the fibrous-root plants was higher than that of the thick-root plants (p = 0.001). The aerenchyma of the fibrous-root plants was composed of large cavities which were formed from many small cavities, and distributed radially between the exodermis and vascular tissues. The aerenchyma of the thick-root plants had a large number of small cavities which were distributed in the mediopellis. The fibrous-root plants had a significantly larger root biomass of D ? 1 mm, of 1 mm < D < 3 mm, above-ground biomass, total biomass, and longer root system, but shorter root longevity than those of the thick-root plants (p = 0.003, 0.018, 0.020, 0.032, 0.042, 0.001). The fibrous-root plants also had significantly higher radial oxygen loss (ROL), root activity, photosynthetic rate, transpiration rate, and removal rates of total nitrogen and total phosphorus than the thick-root plants (p = 0.001, 0.008, 0.010, 0.004, 0.020, 0.002). The results indicate that significantly different root morphological and structural features existed among different wetland plants, and these features had a close relationship to nutrient removal capacity. PMID:21640369

Lai, Wen-Ling; Wang, Shu-Qiang; Peng, Chang-Lian; Chen, Zhang-He

2011-05-11

410

Quantification of gypsum crystal nucleation, growth, and breakage rates in a wet flue gas desulfurization pilot plant  

SciTech Connect

The aim of this work is to study the influence of nucleation, growth and breakage on the particle size distribution (PSD) of gypsum crystals produced by the wet flue gas desulfurization (FGD) process. The steady state PSD, obtained in a falling film wet FGD pilot plant during desulfurization of a 1000 ppm(V) SO{sub 2} gas stream, displayed a strong nonlinear behaviour (in a ln(n(l)) vs. I plot) at the lower end of the particle size range, compared to the well-known linear mixed suspension mixed product removal model. A transient population balance breakage model, fitted to experimental data, was able to model an increase in the fraction of small particles, but not to the extent observed experimentally. A three-parameter, size-dependent growth model, previously used for sodium sulphate decahydrate and potash alum, was able to describe the experimental data, indicating either size-dependent integration kinetics or growth rate dispersion.

Hansen, B.B.; Kiil, S.; Johnsson, J.E. [Technical University of Denmark, Lyngby (Denmark). Dept. of Chemical & Biochemical Engineering

2009-10-15

411

Investigation of the vaporization of boric acid by transpiration thermogravimetry and knudsen effusion mass spectrometry.  

PubMed

The vaporization of H3BO3(s) was studied by using a commercial thermogravimetric apparatus and a Knudsen effusion mass spectrometer. The thermogravimetric measurements involved use of argon as the carrier gas for vapor transport and derivation of vapor pressures of H3BO3(g) in the temperature range 315-352 K through many flow dependence and temperature dependence runs. The vapor pressures as well as the enthalpy of sublimation obtained in this study represent the first results from measurements at low temperatures that are in accord with the previously reported near-classical transpiration measurements (by Stackelberg et al. 70 years ago) at higher temperatures (382-413 K with steam as the carrier gas). The KEMS measurements performed for the first time on boric acid showed H3BO3(g) as the principal vapor species with no meaningful information discernible on H2O(g) though. The thermodynamic parameters, both p(H3BO3) and Delta sub H degrees m(H3BO3,g), deduced from KEMS results in the temperature range 295-342 K are in excellent agreement with the transpiration results lending further credibility to the latter. All this information points toward congruent vaporization at the H3BO3 composition in the H2O-B2O3 binary system. The vapor pressures obtained from transpiration (this study and that of Stackelberg et al.) as well as from KEMS measurements are combined to recommend the following: log [p(H3BO3)/Pa]=-(5199+/-74)/(T/K)+(15.65+/-0.23), valid for T=295-413 K; and Delta sub H degrees m=98.3+/-9.5 kJ mol (-1) at T=298 K for H3BO3(s)=H3BO3(g). PMID:18842023

Balasubramanian, R; Lakshmi Narasimhan, T S; Viswanathan, R; Nalini, S

2008-10-09

412

On the information content of forest transpiration measurements for identifying canopy conductance model parameters  

NASA Astrophysics Data System (ADS)

Generally, forest transpiration models contain model parameters that cannot be measured independently and therefore are tuned to fit the model results to measurements. Only unique parameter estimates with high accuracy can be used for extrapolation in time or space. However, parameter identification problems may occur as a result of the properties of the data set. Time-series of environmental conditions, which control the forest transpiration, may contain periods with redundant or coupled information, so called collinearity, and other combinations of conditions may be measured only with difficulty or incompletely. The aim of this study is to select environmental conditions that yield a unique parameter set of a canopy conductance model. The parameter identification method based on localization of information (PIMLI) was used to calculate the information content of every individual artificial transpiration measurement. It is concluded that every measurement has its own information with respect to a parameter. Independent criteria were assessed to localize the environmental conditions, which