WorldWideScience

Sample records for plant transpiration rate

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

    Science.gov (United States)

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

    2014-09-01

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

  2. Cultivar Differences in Plant Transpiration Rate at High Relative Air Humidity Are Not Related to Genotypic Variation in Stomatal Responsiveness

    DEFF Research Database (Denmark)

    Gebraegziabher, Habtamu Giday; Kjær, Katrine Heinsvig; Ottosen, Carl-Otto

    2015-01-01

    a given cultivar, Tleaf was generally higher, (1.5-3.7°C) at high as compared to moderate RH. Following desiccation, leaf weight loss was differentially enhanced (8-66%) in high RH-grown plants, indicating a wide variation in high RH tolerance. High RH mainly decreased plant water loss during the light......Plants grown at high relative air humidity (RH) often show disturbed water relations due to less responsive stomata. The attenuation of stomatal responsiveness as a result of high RH during leaf expansion depends on the cultivar. We hypothesized that tolerant cultivars to high RH experience a lower...... decline in plant transpiration by high RH, and that the variation in plant transpiration rate can be reflected by differences in leaf temperature (Tleaf). Plant leaf area, stomatal responsiveness to desiccation, together with plant transpiration and leaf temperature at growth conditions were analyzed...

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

    Science.gov (United States)

    Tani, F H; Barrington, S

    2005-12-01

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

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

    Science.gov (United States)

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

    2010-07-01

    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 m(2) 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.

  5. Silver and zinc inhibitors influence transpiration rate and aquaporin transcript levels in intact soybean plants

    Science.gov (United States)

    Some soybean (Glycine max (L.) Merr.) have been identified that expressed limited transpiration rate (TR) above a threshold vapor pressure deficit (VPD). Restriction of TR at high VPD conditions is considered a water conservation trait that allows water to be retained in the soil to benefit of crop...

  6. Surface Acoustic Waves to Drive Plant Transpiration

    Science.gov (United States)

    Gomez, Eliot F.; Berggren, Magnus; Simon, Daniel T.

    2017-03-01

    Emerging fields of research in electronic plants (e-plants) and agro-nanotechnology seek to create more advanced control of plants and their products. Electronic/nanotechnology plant systems strive to seamlessly monitor, harvest, or deliver chemical signals to sense or regulate plant physiology in a controlled manner. Since the plant vascular system (xylem/phloem) is the primary pathway used to transport water, nutrients, and chemical signals—as well as the primary vehicle for current e-plant and phtyo-nanotechnology work—we seek to directly control fluid transport in plants using external energy. Surface acoustic waves generated from piezoelectric substrates were directly coupled into rose leaves, thereby causing water to rapidly evaporate in a highly localized manner only at the site in contact with the actuator. From fluorescent imaging, we find that the technique reliably delivers up to 6x more water/solute to the site actuated by acoustic energy as compared to normal plant transpiration rates and 2x more than heat-assisted evaporation. The technique of increasing natural plant transpiration through acoustic energy could be used to deliver biomolecules, agrochemicals, or future electronic materials at high spatiotemporal resolution to targeted areas in the plant; providing better interaction with plant physiology or to realize more sophisticated cyborg systems.

  7. Transpiration rates of urban trees, Aesculus chinensis

    Institute of Scientific and Technical Information of China (English)

    Hua Wang; Xiaoke Wang; Ping Zhao; Hua Zheng; Yufen Ren; Fuyuan Gao; Zhiyun Ouyang

    2012-01-01

    Transpiration patterns of Aesculus chinensis in relation to explanatory variables in the microclimatic,air quality,and biological phenomena categories were measured in Beijing,China using the thermal dissipation method.The highest transpiration rate measured as the sap flux density of the trees took place from 10:00 am to 13:00 pm in the summer and the lowest was found during nighttime in the winter.To sort out co-linearity,principal component analysis and variation and hierarchical partitioning methods were employed in data analyses.The evaporative demand index (EDI) consisting of air temperature,soil temperature,total radiation,vapor pressure deficit,and atmospheric ozone (O3),explained 68% and 80% of the hourly and daily variations of the tree transpiration,respectively.The independent and joint effects of EDI variables together with a three-variable joint effect exerted the greatest influences on the variance of transpiration rates.The independent effects of leaf area index and atmospheric O3 and their combined effect exhibited minor yet significant influences on ace transpiration rates.

  8. Effects of gravity on transpiration of plant leaves.

    Science.gov (United States)

    Hirai, Hiroaki; Kitaya, Yoshiaki

    2009-04-01

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

  9. Measuring Transpiration to Regulate Winter Irrigation Rates

    Energy Technology Data Exchange (ETDEWEB)

    Samuelson, Lisa [Auburn University

    2006-11-08

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

  10. Global separation of plant transpiration from groundwater and streamflow

    Science.gov (United States)

    Jaivime Evaristo; Scott Jasechko; Jeffrey J. McDonnell

    2015-01-01

    Current land surface models assume that groundwater, streamflow and plant transpiration are all sourced and mediated by the same well mixed water reservoir—the soil. However, recent work in Oregon and Mexico has shown evidence of ecohydrological separation, whereby different subsurface compartmentalized pools of water supply either plant transpiration fluxes or the...

  11. Cultivar Differences in Plant Transpiration Rate at High Relative Air Humidity Are Not Related to Genotypic Variation in Stomatal Responsiveness

    DEFF Research Database (Denmark)

    Gebraegziabher, Habtamu Giday; Kjær, Katrine Heinsvig; Ottosen, Carl-Otto;

    2015-01-01

    Plants grown at high relative air humidity (RH) often show disturbed water relations due to less responsive stomata. The attenuation of stomatal responsiveness as a result of high RH during leaf expansion depends on the cultivar. We hypothesized that tolerant cultivars to high RH experience a lower...... a given cultivar, Tleaf was generally higher, (1.5-3.7°C) at high as compared to moderate RH. Following desiccation, leaf weight loss was differentially enhanced (8-66%) in high RH-grown plants, indicating a wide variation in high RH tolerance. High RH mainly decreased plant water loss during the light...

  12. Fuzzy logic technology for modeling of greenhouse crop transpiration rate

    Science.gov (United States)

    Deng, Lujuan; Wang, Huaishan

    2006-11-01

    The objective of this paper was present a reasonable greenhouse crop transpiration rate model for irrigation scheduling thereby to achieve the best effect, for example, water and energy economizing furthermore to make crop growing better. So it was essential to measure crop transpiration rate. Owing to the difficulty of obtaining accurate real time data of crop transpiration, it was commonly estimated from weather parameters. So the fuzzy logic model for estimation of greenhouse crop transpiration rate was developed. The model was made up of five sub-systems and three layers. There were nine input variables and one output variable. The results of comparison between measured and fuzzy model is inspirer. The squared correlation coefficient (r2) by fuzzy model method (r2=0.9302) is slightly higher than by FAO Penman-Monteith formula (r2=0.9213). The fuzzy logic crop transpiration rate model could be easily extended for irrigation decision-making.

  13. Partial phenotypic reversion of ABA-deficient flacca tomato (Solanum lycopersicum) scions by a wild-type rootstock: normalizing shoot ethylene relations promotes leaf area but does not diminish whole plant transpiration rate.

    Science.gov (United States)

    Dodd, Ian C; Theobald, Julian C; Richer, Sarah K; Davies, William J

    2009-01-01

    To evaluate the role of root-synthesized ABA in regulating growth and stomatal behaviour under well-watered conditions, isogenic wild-type (WT) and ABA-deficient flacca (flc) tomato (Solanum lycopersicum) were reciprocally and self-grafted just below the cotyledonary node. Since flc scions had lower leaf water potentials due to higher transpiration rates, a subset of all graft combinations was grown under a shoot misting treatment to minimize differences in shoot water status. Misting did not alter the relative effects of the different graft combinations on leaf area. WT scions had the greatest leaf area and lowest whole plant transpiration rate irrespective of the rootstock, implying that shoot ABA biosynthesis was sufficient to account for a WT shoot phenotype. In WT scions, the rootstock had no effect on detached leaf ethylene evolution or xylem concentrations of ABA or the ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC). In flc scions, although the WT rootstock suppressed stomatal conductance of individual leaves, there was no detectable effect on whole plant transpiration rate. However, leaf area of flc/WT (scion/rootstock) plants increased 1.6-fold compared to flc self-grafts. WT rootstocks increased xylem ABA concentration in flc scions (relative to flc self-grafts) up to 3-fold, and resulted in xylem ACC concentrations and detached leaf ethylene evolution similar to WT scions. Since the WT rootstock normalized shoot ethylene relations but only partially restored the leaf area of flc scions (relative to that of WT scions), shoot ABA biosynthesis can directly promote leaf area via an unknown, ethylene-independent, mechanism.

  14. Plant factories; crop transpiration and energy balance

    NARCIS (Netherlands)

    Graamans, Luuk; Dobbelsteen, van den Andy; Meinen, Esther; Stanghellini, Cecilia

    2017-01-01

    Population growth and rapid urbanisation may result in a shortage of food supplies for cities in the foreseeable future. Research on closed plant production systems, such as plant factories, has attempted to offer perspectives for robust (urban) agricultural systems. Insight into the explicit role

  15. Transpiration response of boreal forest plants to permafrost thaw

    Science.gov (United States)

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

    2011-12-01

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

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

    Directory of Open Access Journals (Sweden)

    L. B. Menchaca

    2007-04-01

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

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

    Science.gov (United States)

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

    2011-01-01

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

  18. Abscisic acid controlled sex before transpiration in vascular plants.

    Science.gov (United States)

    McAdam, Scott A M; Brodribb, Timothy J; Banks, Jo Ann; Hedrich, Rainer; Atallah, Nadia M; Cai, Chao; Geringer, Michael A; Lind, Christof; Nichols, David S; Stachowski, Kye; Geiger, Dietmar; Sussmilch, Frances C

    2016-10-26

    Sexual reproduction in animals and plants shares common elements, including sperm and egg production, but unlike animals, little is known about the regulatory pathways that determine the sex of plants. Here we use mutants and gene silencing in a fern species to identify a core regulatory mechanism in plant sexual differentiation. A key player in fern sex differentiation is the phytohormone abscisic acid (ABA), which regulates the sex ratio of male to hermaphrodite tissues during the reproductive cycle. Our analysis shows that in the fern Ceratopteris richardii, a gene homologous to core ABA transduction genes in flowering plants [SNF1-related kinase2s (SnRK2s)] is primarily responsible for the hormonal control of sex determination. Furthermore, we provide evidence that this ABA-SnRK2 signaling pathway has transitioned from determining the sex of ferns to controlling seed dormancy in the earliest seed plants before being co-opted to control transpiration and CO2 exchange in derived seed plants. By tracing the evolutionary history of this ABA signaling pathway from plant reproduction through to its role in the global regulation of plant-atmosphere gas exchange during the last 450 million years, we highlight the extraordinary effect of the ABA-SnRK2 signaling pathway in plant evolution and vegetation function.

  19. Gravimetric phenotyping of whole plant transpiration responses to atmospheric vapour pressure deficit identifies genotypic variation in water use efficiency.

    Science.gov (United States)

    Ryan, Annette C; Dodd, Ian C; Rothwell, Shane A; Jones, Ros; Tardieu, Francois; Draye, Xavier; Davies, William J

    2016-10-01

    There is increasing interest in rapidly identifying genotypes with improved water use efficiency, exemplified by the development of whole plant phenotyping platforms that automatically measure plant growth and water use. Transpirational responses to atmospheric vapour pressure deficit (VPD) and whole plant water use efficiency (WUE, defined as the accumulation of above ground biomass per unit of water used) were measured in 100 maize (Zea mays L.) genotypes. Using a glasshouse based phenotyping platform with naturally varying VPD (1.5-3.8kPa), a 2-fold variation in WUE was identified in well-watered plants. Regression analysis of transpiration versus VPD under these conditions, and subsequent whole plant gas exchange at imposed VPDs (0.8-3.4kPa) showed identical responses in specific genotypes. Genotype response of transpiration versus VPD fell into two categories: 1) a linear increase in transpiration rate with VPD with low (high WUE) or high (low WUE) transpiration rate at all VPDs, 2) a non-linear response with a pronounced change point at low VPD (high WUE) or high VPD (low WUE). In the latter group, high WUE genotypes required a significantly lower VPD before transpiration was restricted, and had a significantly lower rate of transpiration in response to VPD after this point, when compared to low WUE genotypes. Change point values were significantly positively correlated with stomatal sensitivity to VPD. A change point in stomatal response to VPD may explain why some genotypes show contradictory WUE rankings according to whether they are measured under glasshouse or field conditions. Furthermore, this novel use of a high throughput phenotyping platform successfully reproduced the gas exchange responses of individuals measured in whole plant chambers, accelerating the identification of plants with high WUE. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  20. Hydrogen isotope composition of leaf wax n-alkanes in Arabidopsis lines with different transpiration rates

    Science.gov (United States)

    Pedentchouk, N.; Lawson, T.; Eley, Y.; McAusland, L.

    2012-04-01

    Stable isotopic compositions of oxygen and hydrogen are used widely to investigate modern and ancient water cycles. The D/H composition of organic compounds derived from terrestrial plants has recently attracted significant attention as a proxy for palaeohydrology. However, the role of various plant physiological and biochemical factors in controlling the D/H signature of leaf wax lipids in extant plants remains unclear. The focus of this study is to investigate the effect of plant transpiration on the D/H composition of n-alkanes in terrestrial plants. This experiment includes 4 varieties of Arabidopsis thaliana that differ with respect to stomatal density and stomatal geometry. All 4 varieties were grown indoors under identical temperature, relative humidity, light and watering regimes and then sampled for leaf wax and leaf water stable isotopic measurements. During growth, stomatal conductance to carbon dioxide and water vapour were also determined. We found that the plants varied significantly in terms of their transpiration rates. Transpiration rates were significantly higher in Arabidopsis ost1 and ost1-1 varieties (2.4 and 3.2 mmol m-2 s-1, respectively) than in Arabidopsis RbohD and Col-0 (1.5 and 1.4). However, hydrogen isotope measurements of n-alkanes extracted from leaf waxes revealed a very different pattern. Varieties ost1, ost1-1, and RbohD have very similar deltaD values of n-C29 alkane (-125, -128, and -127 per mil), whereas the deltaD value of Col-0 is more negative (-137 per mil). The initial results of this work suggest that plant transpiration is decoupled from the D/H composition of n-alkanes. In other words, physical processes that affect water vapour movement between the plant and its environment apparently cannot account for the stable hydrogen isotope composition of organic compounds that comprise leaf waxes. Additional, perhaps biochemical, processes that affect hydrogen isotope fractionation during photosynthesis might need to be invoked

  1. Measuring whole-plant transpiration gravimetrically: a scalable automated system built from components

    Science.gov (United States)

    Damian Cirelli; Victor J. Lieffers; Melvin T. Tyree

    2012-01-01

    Measuring whole-plant transpiration is highly relevant considering the increasing interest in understanding and improving plant water use at the whole-plant level. We present an original software package (Amalthea) and a design to create a system for measuring transpiration using laboratory balances based on the readily available commodity hardware. The system is...

  2. Responses of soil CO2 efflux to changes in plant CO2 uptake and transpiration

    Science.gov (United States)

    Balogh, János; de Luca, Giulia; Mészáros, Ádám; Trieber, Júlia; Gecse, Bernadett; Fóti, Szilvia; Pintér, Krisztina; Nagy, Zoltán

    2017-04-01

    results, the effect of the assimilated CO2 appeared after 3 hours in soil CO2 efflux. The lack of light (24 hours) caused 20% decrease in total soil CO2 efflux. The decrease of the plant transpiration rate slightly increased the autotrophic component. These responses could be useful in clarifying the drivers behind the diel variability of soil respiration.

  3. Modeling water potentials and flows in the soil-plant system comparing hydraulic resistances and transpiration reduction fuctions

    NARCIS (Netherlands)

    Jong, de Q.; Dam, van J.C.; Durigon, A.; Santos, dos M.A.; Metselaar, K.

    2013-01-01

    Crop transpiration depends on resistances in the soil–plant–atmosphere system. We present a new deterministic root water uptake model to estimate transpiration and compare it with two other models. We show the sensitivity of actual transpiration to parameters like soil and plant hydraulic properties

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

    Directory of Open Access Journals (Sweden)

    Li Jingmin

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

  5. Assessment of actual transpiration rate in olive tree field combining sap-flow, leaf area index and scintillometer measurements

    Science.gov (United States)

    Agnese, C.; Cammalleri, C.; Ciraolo, G.; Minacapilli, M.; Provenzano, G.; Rallo, G.; de Bruin, H. A. R.

    2009-09-01

    Models to estimate the actual evapotranspiration (ET) in sparse vegetation area can be fundamental for agricultural water managements, especially when water availability is a limiting factor. Models validation must be carried out by considering in situ measurements referred to the field scale, which is the relevant scale of the modelled variables. Moreover, a particular relevance assumes to consider separately the components of plant transpiration (T) and soil evaporation (E), because only the first is actually related to the crop stress conditions. Objective of the paper was to assess a procedure aimed to estimate olive trees actual transpiration by combining sap flow measurements with the scintillometer technique at field scale. The study area, located in Western Sicily (Italy), is mainly cultivated with olive crop and is characterized by typical Mediterranean semi-arid climate. Measurements of sap flow and crop actual evapotranspiration rate were carried out during 2008 irrigation season. Crop transpiration fluxes, measured on some plants by means of sap flow sensors, were upscaled considering the leaf area index (LAI). The comparison between evapotranspiration values, derived by displaced-beam small-aperture scintillometer (DBSAS-SLS20, Scintec AG), with the transpiration fluxes obtained by the sap flow sensors, also allowed to evaluate the contribute of soil evaporation in an area characterized by low vegetation coverage.

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

    Directory of Open Access Journals (Sweden)

    Irineo Torres-Pacheco

    2010-09-01

    Full Text Available 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.

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

    Science.gov (United States)

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

    2010-01-01

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

  8. Forcing variables in simulation of transpiration of water stressed plants determined by principal component analysis

    Science.gov (United States)

    Durigon, Angelica; Lier, Quirijn de Jong van; Metselaar, Klaas

    2016-10-01

    To date, measuring plant transpiration at canopy scale is laborious and its estimation by numerical modelling can be used to assess high time frequency data. When using the model by Jacobs (1994) to simulate transpiration of water stressed plants it needs to be reparametrized. We compare the importance of model variables affecting simulated transpiration of water stressed plants. A systematic literature review was performed to recover existing parameterizations to be tested in the model. Data from a field experiment with common bean under full and deficit irrigation were used to correlate estimations to forcing variables applying principal component analysis. New parameterizations resulted in a moderate reduction of prediction errors and in an increase in model performance. Ags model was sensitive to changes in the mesophyll conductance and leaf angle distribution parameterizations, allowing model improvement. Simulated transpiration could be separated in temporal components. Daily, afternoon depression and long-term components for the fully irrigated treatment were more related to atmospheric forcing variables (specific humidity deficit between stomata and air, relative air humidity and canopy temperature). Daily and afternoon depression components for the deficit-irrigated treatment were related to both atmospheric and soil dryness, and long-term component was related to soil dryness.

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

    Science.gov (United States)

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

    2010-06-01

    The measurement system of Li-8100 carbon flux and the modified assimilation chamber were used to study the photosynthetic characteristics of cotton (Gossypium hirsutum L.) canopy in the oasis edge region in middle reach of Heihe River Basin, mid Hexi Corridor of Gansu. At the experimental site, soil respiration and evaporation rates were significantly higher in late June than in early August, and the diurnal variation of canopy photosynthetic rate showed single-peak type. The photosynthetic rate was significantly higher (P rate also presented single-peak type, with the daily average value in late June and early August being (3.10 +/- 0.34) mmol H2O x m(-2) x s(-1) and (1.60 +/- 0.26) mmol H2O x m(-2) x s(-1), respectively, and differed significantly (P 0.05). Both in late June and in early August, the canopy photosynthetic rate was positively correlated with air temperature, PAR, and soil moisture content, suggesting that there was no midday depression of photosynthesis in the two periods. In August, the canopy photosynthetic rate and transpiration rate decreased significantly, because of the lower soil moisture content and leaf senescence, but the canopy water use efficiency had no significant decrease.

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

    Science.gov (United States)

    Roderick, Michael

    2013-04-01

    observations that win. That is the basis of science. In this Dalton Medal lecture we first examine pan evaporation observations and show why pan evaporation has declined. Armed with that knowledge we then investigate the consequences for plant water use and how this is directly coupled to the catchment water balance.

  11. A Laboratory Exercise to Assess Transpiration.

    Science.gov (United States)

    Schrock, Gould F.

    1982-01-01

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

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

    Science.gov (United States)

    Nir, Ido; Moshelion, Menachem; Weiss, David

    2014-01-01

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

  13. Transpiration and metabolisation of TCE by willow plants - a pot experiment.

    Science.gov (United States)

    Schöftner, Philipp; Watzinger, Andrea; Holzknecht, Philipp; Wimmer, Bernhard; Reichenauer, Thomas G

    2016-01-01

    Willows were grown in glass cylinders filled with compost above water-saturated quartz sand, to trace the fate of TCE in water and plant biomass. The experiment was repeated once with the same plants in two consecutive years. TCE was added in nominal concentrations of 0, 144, 288, and 721 mg l(-1). Unplanted cylinders were set-up and spiked with nominal concentrations of 721 mg l(-1) TCE in the second year. Additionally, (13)C-enriched TCE solution (δ(13)C = 110.3 ‰) was used. Periodically, TCE content and metabolites were analyzed in water and plant biomass. The presence of TCE-degrading microorganisms was monitored via the measurement of the isotopic ratio of carbon ((13)C/(12)C) in TCE, and the abundance of (13)C-labeled microbial PLFAs (phospholipid fatty acids). More than 98% of TCE was lost via evapotranspiration from the planted pots within one month after adding TCE. Transpiration accounted to 94 to 78% of the total evapotranspiration loss. Almost 1% of TCE was metabolized in the shoots, whereby trichloroacetic acid (TCAA) and dichloroacetic acid (DCAA) were dominant metabolites; less trichloroethanol (TCOH) and TCE accumulated in plant tissues. Microbial degradation was ruled out by δ(13)C measurements of water and PLFAs. TCE had no detected influence on plant stress status as determined by chlorophyll-fluorescence and gas exchange.

  14. High resolution mapping of traits related to whole-plant transpiration under increasing evaporative demand in wheat.

    Science.gov (United States)

    Schoppach, Rémy; Taylor, Julian D; Majerus, Elisabeth; Claverie, Elodie; Baumann, Ute; Suchecki, Radoslaw; Fleury, Delphine; Sadok, Walid

    2016-04-01

    Atmospheric vapor pressure deficit (VPD) is a key component of drought and has a strong influence on yields. Whole-plant transpiration rate (TR) response to increasing VPD has been linked to drought tolerance in wheat, but because of its challenging phenotyping, its genetic basis remains unexplored. Further, the genetic control of other key traits linked to daytime TR such as leaf area, stomata densities and - more recently - nocturnal transpiration remains unknown. Considering the presence of wheat phenology genes that can interfere with drought tolerance, the aim of this investigation was to identify at an enhanced resolution the genetic basis of the above traits while investigating the effects of phenology genes Ppd-D1 and Ppd-B1 Virtually all traits were highly heritable (heritabilities from 0.61 to 0.91) and a total of mostly trait-specific 68 QTL were detected. Six QTL were identified for TR response to VPD, with one QTL (QSLP.ucl-5A) individually explaining 25.4% of the genetic variance. This QTL harbored several genes previously reported to be involved in ABA signaling, interaction with DREB2A and root hydraulics. Surprisingly, nocturnal TR and stomata densities on both leaf sides were characterized by highly specific and robust QTL. In addition, negative correlations were found between TR and leaf area suggesting trade-offs between these traits. Further, Ppd-D1 had strong but opposite effects on these traits, suggesting an involvement in this trade-off. Overall, these findings revealed novel genetic resources while suggesting a more direct role of phenology genes in enhancing wheat drought tolerance.

  15. Enhanced transpiration rate in the high pigment 1 tomato mutant and its physiological significance.

    Science.gov (United States)

    Carvalho, R F; Aidar, S T; Azevedo, R A; Dodd, I C; Peres, L E P

    2011-05-01

    Tomato high pigment (hp) mutants represent an interesting horticultural resource due to their enhanced accumulation of carotenoids, flavonoids and vitamin C. Since hp mutants are known for their exaggerated light responses, the molecules accumulated are likely to be antioxidants, recruited to deal with light and others stresses. Further phenotypes displayed by hp mutations are reduced growth and an apparent disturbance in water loss. Here, we examined the impact of the hp1 mutation and its near isogenic line cv Micro-Tom (MT) on stomatal conductance (gs), transpiration (E), CO(2) assimilation (A) and water use efficiency (WUE). Detached hp1 leaves lost water more rapidly than control leaves, but this behaviour was reversed by exogenous abscisic acid (ABA), indicating the ability of hp1 to respond to this hormone. Although attached hp1 leaves had enhanced gs, E and A compared to control leaves, genotypic differences were lost when water was withheld. Both instantaneous leaf-level WUE and long-term whole plant WUE did not differ between hp1 and MT. Our results indicate a link between exaggerated light response and water loss in hp1, which has important implications for the use of this mutant in both basic and horticultural research.

  16. Phosphate Distribution and Movement in Soil—Root Interface Zone:I.The Influence of Transpiration Rate

    Institute of Scientific and Technical Information of China (English)

    XUMING-GANG; ZHANGYI-PING; 等

    1995-01-01

    The experiments were conducted in the artificial climate laboratory using 32P labelled soil and soil-root plane system to investigate phosphate distribution and its movement in the soil-root interface zone and their relations with phosphate uptake by plant as well as transpiration rate (atmosphere humidity).It was found that although the phosphate in the soil-root interface zone was of depletive distribution as a function C/Co=axb(C/Co is the relative content of fertilizer phosphate in a distance from the root surface x,a and b are the regression constants),and a relative accumulation zone of phosphate within 0.5 mm near the root surface was often boserved especially in the heavier texture soils because of root phosphate secretion.The depletion intensity of phosphate in the soil-root interface zone was in agreement with the phophate uptake by plants under two humidities very well.However,the effects of air humidity on characteristics of the phosphate distribution near wheat or maize root surface were different.Wheat grew better under lower atmosphere humidity while maize,under higher humidity,which caused a more intensive uptake and thus a stronger depletion of phosphate in the rhizosphere,Moreover,the depletion intensity was greater by the bottom or the middle part of wheat roots and by the top or the middle part of maize roots.The depletive distribution of phosphate in the rhizosphere soil and the relative contribution of phosphate diffusion to plant,which was more than 98% in the cultural experiments,indicated that diffusion was a major process for phosphorus supply to plants.

  17. The uptake and transpiration of water and the accumulation of lead by plants growing on lead chloride solutions

    Directory of Open Access Journals (Sweden)

    Marek Burzyński

    2014-01-01

    Full Text Available The placement of approximately two week-old bean, cucumber and wheat plants in PbCl2 solutions caused significant decreases in transpiration and uptake of water. The amount of transpiration and water uptake depended on the PbCl2 concentration and length of treatment. Cucumber plants were the most sensitive to lead and accumu-lated the. greatest amounts of it. Beans were the least sensitive, although they accumulated more lead than wheat. The lead taken up by cucumbers and beans accumulated mainly in the roots while the distribution of lead in wheat was rather uniform in the roots and above-ground parts. The removal of roots from bean plants caused high accumulation of lead in the lower stem parts.

  18. Interannual environmental-soil thawing rate variation and its control on transpiration from Larix cajanderi, Central Yakutia, Eastern Siberia

    Science.gov (United States)

    Lopez C, M. L.; Saito, H.; Kobayashi, Y.; Shirota, T.; Iwahana, G.; Maximov, T. C.; Fukuda, M.

    2007-05-01

    SummarySapflow measurements were carried out in a larch forest in eastern Siberia, an area of wide permafrost distribution. Canopy transpiration and canopy conductance were scaled up from these values. The objective was to analyze the relationship between environmental variables, mainly vapour pressure deficit ( D), soil moisture and soil thawing rate with canopy transpiration and canopy conductance. Maximum sapflow rate was 42.4 kg d -1 tree -1 with bigger trees showing a more accentuated response to environmental changes. Canopy transpiration ( Ec) showed inter-annual variability, with a maximum value of 1.7 mm d -1 in 2003 and 1.2 mm d -1 in 2004. Soil moisture was higher in 2003 because of higher precipitation (230 mm in 2003 compared to 110 mm in 2004 for the total growing season). Maximum soil thawing rate in 2003 and 2004 was 140 cm and 120 cm, respectively, because of different air temperature, soil water content and precipitation regime among other factors. Canopy conductance ( gc) was positively correlated with D during fine weather and well-watered days in both years. On the other hand, canopy conductance was well correlated with soil moisture ( R2 = 0.83) in the upper layers (20-30 cm depth) during 2003 (wet year) but not in 2004 (dry year), representing its strong but limited control over water fluxes from the forest. By comparison with other studies in this region, canopy transpiration is estimated to contribute to almost 50% of the total forest evaporation, highlighting the important role of understorey transpiration in permafrost regions. Our results show that it is not only the impermeability of permafrost with the property of keeping soil moisture in the thin active layer but it is also the slow soil thawing rate that plays the important role of controlling the amount of water available for trees roots in the upper soil layers during dry years.

  19. Sapfluxnet: a global database of sap flow measurements to unravel the ecological factors of transpiration regulation in woody plants

    Science.gov (United States)

    Poyatos, Rafael; Martínez-Vilalta, Jordi; Molowny-Horas, Roberto; Steppe, Kathy; Oren, Ram; Katul, Gabriel; Mahecha, Miguel

    2016-04-01

    Plant transpiration is one of the main components of the global water cycle, it controls land energy balance, determines catchment hydrological responses and exerts strong feedbacks on regional and global climate. At the same time, plant productivity, growth and survival are severely constrained by water availability, which is expected to decline in many areas of the world because of global-change driven increases in drought conditions. While global surveys of drought tolerance traits at the organ level are rapidly increasing our knowledge of the diversity in plant functional strategies to cope with drought stress, a whole-plant perspective of drought vulnerability is still lacking. Sap flow measurements using thermal methods have now been applied to measure seasonal patterns in water use and the response of transpiration to environmental drivers across hundreds of species of woody plants worldwide, covering a wide range of climates, soils and stand structural characteristics. Here, we present the first effort to build a global database of sub-daily, tree-level sap flow (SAPFLUXNET) that will be used to improve our understanding of physiological and structural determinants of plant transpiration and to further investigate the role of vegetation in controlling global water balance. We already have the expression of interest of data contributors representing >115 globally distributed sites, > 185 species and > 700 trees, measured over at least one growing season. However, the potential number of available sites and species is probably much higher given that > 2500 sap flow-related papers have been identified in a Scopus literature search conducted in November 2015. We will give an overview of how data collection, harmonisation and quality control procedures are implemented within the project. We will also discuss potential analytical strategies to synthesize hydroclimatic controls on sap flow into biologically meaningful traits related to whole-plant transpiration

  20. Effectiveness of cuticular transpiration barriers in a desert plant at controlling water loss at high temperatures.

    Science.gov (United States)

    Schuster, Ann-Christin; Burghardt, Markus; Alfarhan, Ahmed; Bueno, Amauri; Hedrich, Rainer; Leide, Jana; Thomas, Jacob; Riederer, Markus

    2016-01-01

    Maintaining the integrity of the cuticular transpiration barrier even at elevated temperatures is of vital importance especially for hot-desert plants. Currently, the temperature dependence of the leaf cuticular water permeability and its relationship with the chemistry of the cuticles are not known for a single desert plant. This study investigates whether (i) the cuticular permeability of a desert plant is lower than that of species from non-desert habitats, (ii) the temperature-dependent increase of permeability is less pronounced than in those species and (iii) whether the susceptibility of the cuticular permeability barrier to high temperatures is related to the amounts or properties of the cutin or the cuticular waxes. We test these questions with Rhazya stricta using the minimum leaf water vapour conductance (gmin) as a proxy for cuticular water permeability. gmin of R. stricta (5.41 × 10(-5) m s(-1) at 25 °C) is in the upper range of all existing data for woody species from various non-desert habitats. At the same time, in R. stricta, the effect of temperature (15-50 °C) on gmin (2.4-fold) is lower than in all other species (up to 12-fold). Rhazya stricta is also special since the temperature dependence of gmin does not become steeper above a certain transition temperature. For identifying the chemical and physical foundation of this phenomenon, the amounts and the compositions of cuticular waxes and cutin were determined. The leaf cuticular wax (251.4 μg cm(-2)) is mainly composed of pentacyclic triterpenoids (85.2% of total wax) while long-chain aliphatics contribute only 3.4%. In comparison with many other species, the triterpenoid-to-cutin ratio of R. stricta (0.63) is high. We propose that the triterpenoids deposited within the cutin matrix restrict the thermal expansion of the polymer and, thus, prevent thermal damage to the highly ordered aliphatic wax barrier even at high temperatures.

  1. Steady state nutrition by transpiration controlled nutrient supply

    OpenAIRE

    Braakhekke, W.G.; Labe, D. A.

    1990-01-01

    Programmed nutrient addition with a constant relative addition rate has been advocated as a suitable research technique for inducing steady state nutrition in exponentially growing plants. Transpiration controlled nutrient supply is proposed as an alternative technique for plants with a short or no exponential growth phase. A two-weeks experiment with transpiration controlled nitrogen supply to Pennisetum americanum was carried out to evaluate this method. After an adaptation phase a constant...

  2. Transpiration rates and canopy conductance of Pinus radiata growing with different pasture understories in agroforestry systems.

    Science.gov (United States)

    Miller, Blair J.; Clinton, Peter W.; Buchan, Graeme D.; Robson, A. Bruce

    1998-01-01

    We measured tree transpiration and canopy conductance in Pinus radiata D. Don at two low rainfall sites of differing soil fertility in Canterbury, New Zealand. At the more fertile Lincoln site, we also assessed the effects of two common pasture grasses on tree transpiration and canopy conductance. At the less fertile Eyrewell Forest site, the effect of no understory, and the effects of irrigation in combination with mixtures of grass or legume species were determined. Tree xylem sap flux (F(d)') was measured by the heat pulse method. Total canopy conductance to diffusion of water vapor (G(t)) was calculated by inverting a simplified Penman-Monteith model. The different treatment effects were modeled by the simple decaying exponential relationship G(t) = G(tmax)e((-bD)), where D = air saturation deficit. At the Lincoln site, trees with an understory of cocksfoot had lower F(d)' and G(tmax) than trees with an understory of ryegrass, although the sensitivity of G(t) to increasing D (i.e., the value of b) did not differ between treatments. At the Eyrewell site, irrigation only increased F(d)' in the absence of an understory, whereas the presence of understory vegetation, or lack of irrigation, or both, significantly reduced G(tmax) and increased b. We conclude that the selection of understory species is critical in designing successful agroforestry systems for low rainfall areas.

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

    Science.gov (United States)

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

    2015-04-01

    Poplar genotypes differ in transpiration efficiency (TE) at leaf and whole-plant level under similar conditions. We tested whether atmospheric vapour pressure deficit (VPD) affected TE to the same extent across genotypes. Six Populus nigra genotypes were grown under two VPD. We recorded (1) (13)C content in soluble sugars; (2) (18)O enrichment in leaf water; (3) leaf-level gas exchange; and (4) whole-plant biomass accumulation and water use. Whole-plant and intrinsic leaf TE and (13)C content in soluble sugars differed significantly among genotypes. Stomatal conductance contributed more to these differences than net CO2 assimilation rate. VPD increased water use and reduced whole-plant TE. It increased intrinsic leaf-level TE due to a decline in stomatal conductance. It also promoted higher (18)O enrichment in leaf water. VPD had no genotype-specific effect. We detected a deviation in the relationship between (13)C in leaf sugars and (13)C predicted from gas exchange and the standard discrimination model. This may be partly due to genotypic differences in mesophyll conductance, and to its lack of sensitivity to VPD. Leaf-level (13)C discrimination was a powerful predictor of the genetic variability of whole-plant TE irrespective of VPD during growth. © 2014 John Wiley & Sons Ltd.

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

    Directory of Open Access Journals (Sweden)

    Arvo Tullus

    Full Text Available 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.

  5. Water- and nitrogen-dependent alterations in the inheritance mode of transpiration efficiency in winter wheat at the leaf and whole-plant level.

    Science.gov (United States)

    Ratajczak, Dominika; Górny, Andrzej G

    2012-11-01

    The effects of contrasting water and nitrogen (N) supply on the observed inheritance mode of transpiration efficiency (TE) at the flag-leaf and whole-season levels were examined in winter wheat. Major components of the photosynthetic capacity of leaves and the season-integrated efficiency of water use in vegetative and grain mass formation were evaluated in parental lines of various origins and their diallel F(2)-hybrids grown in a factorial experiment under different moisture and N status of the soil. A broad genetic variation was mainly found for the season-long TE measures. The variation range in the leaf photosynthetic indices was usually narrow, but tended to slightly enhance under water and N shortage. Genotype-treatment interaction effects were significant for most characters. No consistency between the leaf- and season-long TE measures was observed. Preponderance of additivity-dependent variance was mainly identified for the season-integrated TE and leaf CO(2) assimilation rate. Soil treatments exhibited considerable influence on the phenotypic expression of gene action for the residual leaf measures. The contribution of non-additive gene effects and degree of dominance tended to increase in water- and N-limited plants, especially for the leaf transpiration rate and stomatal conductance. The results indicate that promise exists to improve the season-integrated TE. However, selection for TE components should be prolonged for later hybrid generations to eliminate the masking of non-additive causes. Such evaluation among families grown under sub-optimal water and nitrogen supply seems to be the most promising strategy in winter wheat.

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

    Science.gov (United States)

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

    2014-11-01

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

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

    Science.gov (United States)

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

    2014-05-01

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

  8. Efficacy of Physiologically Active Anti-Transpirants on Excised Leaves of Potted Plants

    NARCIS (Netherlands)

    Besufkad Degif, A.; Woltering, E.J.

    2015-01-01

    Pot plant production in the greenhouse is most of the time under high relative humidity and frequent irrigation. While, during shipping and retailing plants may be exposed to high temperature and infrequent irrigation. These unfavorable conditions often cause water loss, desiccation of plants and sh

  9. Steady state nutrition by transpiration controlled nutrient supply

    NARCIS (Netherlands)

    Braakhekke, W.G.; Labe, D.A.

    1990-01-01

    Programmed nutrient addition with a constant relative addition rate has been advocated as a suitable research technique for inducing steady state nutrition in exponentially growing plants. Transpiration controlled nutrient supply is proposed as an alternative technique for plants with a short or no

  10. Modelling of water potential and water uptake rate of tomato plants in the greenhouse: preliminary results.

    NARCIS (Netherlands)

    Bruggink, G.T.; Schouwink, H.E.; Gieling, Th.H.

    1988-01-01

    A dynamic model is presented which predicts water potential and water uptake rate of greenhouse tomato plants using transpiration rate as input. The model assumes that water uptake is the resultant of water potential and hydraulic resistance, and that water potential is linearly related to water con

  11. Plant water resource partitioning and isotopic fractionation during transpiration in a seasonally dry tropical climate

    Science.gov (United States)

    De Wispelaere, Lien; Bodé, Samuel; Hervé-Fernández, Pedro; Hemp, Andreas; Verschuren, Dirk; Boeckx, Pascal

    2017-01-01

    Lake Chala (3°19' S, 37°42' E) is a steep-sided crater lake situated in equatorial East Africa, a tropical semiarid area with a bimodal rainfall pattern. Plants in this region are exposed to a prolonged dry season, and we investigated if (1) these plants show spatial variability and temporal shifts in their water source use; (2) seasonal differences in the isotopic composition of precipitation are reflected in xylem water; and (3) plant family, growth form, leaf phenology, habitat and season influence the xylem-to-leaf water deuterium enrichment. In this study, the δ2H and δ18O of precipitation, lake water, groundwater, plant xylem water and plant leaf water were measured across different plant species, seasons and plant habitats in the vicinity of Lake Chala. We found that plants rely mostly on water from the short rains falling from October to December (northeastern monsoon), as these recharge the soil after the long dry season. This plant-available, static water pool is only slightly replenished by the long rains falling from February to May (southeastern monsoon), in agreement with the two water worlds hypothesis, according to which plants rely on a static water pool while a mobile water pool recharges the groundwater. Spatial variability in water resource use exists in the study region, with plants at the lakeshore relying on a water source admixed with lake water. Leaf phenology does not affect water resource use. According to our results, plant species and their associated leaf phenology are the primary factors influencing the enrichment in deuterium from xylem water to leaf water (ɛl/x), with deciduous species giving the highest enrichment, while growth form and season have negligible effects. Our observations have important implications for the interpretation of δ2H of plant leaf wax n-alkanes (δ2Hwax) from paleohydrological records in tropical East Africa, given that the temporal variability in the isotopic composition of precipitation is not

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

    Science.gov (United States)

    Sharkey, T D

    1984-02-01

    High transpiration rates were found to affect the photosynthetic capacity of Xanthium strumarium L. leaves in a manner analagous to that of low soil water potential. The effect was also looked for and found in Gossypium hirsutum L., Agathis robusta (C. Moore ex Muell.) Bailey, Eucalyptus microcarpa Maiden, Larrea divaricata Cav., the wilty flacca tomato mutant (Lycopersicon esculentum (L.) Mill.) and Scrophularia desertorum (Munz) Shaw. Two methods were used to distinguish between effects on stomatal conductance, which can lower assimilation by reducing CO2 availability, and effects on the photosynthetic capacity of the mesophyll. First, the response of assimilation to intercellular CO2 pressure (C i) was compared under conditions of high and low transpiration. Second, in addition to estimating C i using the usual Ohm's law analogy, C i was measured directly using the closed-loop technique of T.D. Sharkey, K. Imai, G.D. Farquhar and I.R. Cowan (1982, Plant Physiol, 60, 657-659). Transpiration stress responses of Xanthium strumarium were compared with soil drought effects. Both stresses reduced photosynthesis at high C i but not at low C i; transpiration stress increased the quantum requirement of photosynthesis. Transpiration stress could be induced in small sections of leaves. Total transpiration from the plant did not influence the photosynthetic capacity of a leaf kept under constant conditions, indicating that water deficits develop over small areas within the leaf. The effect of high transpiration on photosynthesis was reversed approximately half-way by returning the plants to low-transpiration conditions. This reversal occurred as fast as measurements could be made (5 min), but little further recovery was observed in subsequent hours.

  13. Using ISBA model for partitioning evapotranspiration into soil evaporation and plant transpiration of irrigated crops under semi-arid climate

    Science.gov (United States)

    Aouade, Ghizlane; Jarlan, Lionel; Ezzahar, Jamal; Er-raki, Salah; Napoly, Adrien; Benkaddour, Abdelfettah; Khabba, Said; Boulet, Gilles; Chehbouni, Abdelghani; Boone, Aaron

    2016-04-01

    The Haouz region, typical of southern Mediterranean basins, is characterized by a semi-arid climate, with average annual rainfall of 250, whilst evaporative demand is about 1600 mm per year. Under these conditions, crop irrigation is inevitable for growth and development. Irrigated agriculture currently consumes the majority of total available water (up to 85%), making it critical for more efficient water use. Flood irrigation is widely practiced by the majority of the farmers (more than 85 %) with an efficiency which does not exceed 50%. In this context, a good knowledge of the partitioning of evapotranspiration (ET) into soil evaporation and plant transpiration is of crucial need for improving the irrigation scheduling and thus water use efficiency. In this study, the ISBA (Interactions Soil-Biosphere-Atmosphere) model was used for estimating ET and its partition over an olive orchard and a wheat field located near to the Marrakech City (Centre of Morocco). Two versions were evaluated: standard version which simulates a single energy balance for the soil and vegetation and the recently developed multiple energy balance (MEB) version which solves a separate energy balance for each of the two sources. Eddy covariance system, which provides the sensible and latent heat fluxes and meteorological instruments were operated during years 2003-2004 for the Olive Orchard and during years 2013 for wheat. The transpiration component was measured using a Sap flow system during summer over the wheat crop and stable isotope samples were gathered over wheat. The comparison between ET estimated by ISBA model and that measured by the Eddy covariance system showed that MEB version yielded a remarkable improvement compared to the standard version. The root mean square error (RMSE) and the correlation coefficient (R²) were about 45wm-2 and 0.8 for MEB version. By contrast, for the standard version, the RMSE and R² were about 60wm-2 and 0.7, respectively. The result also showed that

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

    Science.gov (United States)

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

    2010-04-01

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

  15. Effects of exogenous 5-aminolevulinic acid on photosynthesis, stomatal conductance, transpiration rate, and PIP gene expression of tomato seedlings subject to salinity stress.

    Science.gov (United States)

    Zhao, Y Y; Yan, F; Hu, L P; Zhou, X T; Zou, Z R; Cui, L R

    2015-06-11

    The effects of exogenous 5-aminolevulinic acid (ALA) on photosynthesis, plant growth, and the expression of two aquaporin genes in tomato seedlings under control and salinity conditions were investigated. Exogenous ALA application significantly improved net photosynthetic rate (Pn), total chlorophyll content, and plant biomass accumulation of tomato seedlings under salinity stress. As revealed by real-time PCR analyses, after treatment with ALA alone, expression of both LePIP1 and LePIP2 in the two tomato cultivars was up-regulated at 2 h and subsequently decreased to normal levels. Under salinity stress, transcript levels of LePIP1 in both leaves and roots of salt-sensitive cultivars (cv. Zhongza No.9) increased significantly and were considerably higher than in cultivars exposed to ALA alone. In contrast, the expression levels of LePIP1 and LePIP2 in cvs. Jinpeng No.1 cultivars were slightly lower under salinity stress than under ALA treatment. In addition, transcript levels of both LePIP1 and LePIP2 in the roots of Jinpeng No. 1 cultivars were considerably lower than those in the roots of Zhongza No. 9 cultivars under salinity stress, regardless of ALA supplementation, implying that Jinpeng No. 1 cultivars had a better capacity to maintain membrane intrinsic protein stability. Further, ALA application distinctly counteracted the up- or down-regulation of LePIP1 and LePIP2 in both cultivars under salinity stress, in accordance with the improvements instomatal conductance, transpiration rate, and Pn of tomato leaves. The results presented here indicate that ALA controls aquaporin expression, thus, presumably ALA regulates water homeostasis and enhances salt tolerance of tomato seedlings.

  16. Wheat Transpiration Response to Soil Heterogeneity

    Science.gov (United States)

    Langensiepen, M.; Kupisch, M.; Cai, G.; Vanderborght, J.; Stadler, A.; Hüging, H.; Ewert, F.

    2014-12-01

    Measuring sap-flow in thin wheat tillers has been difficult so far due to technical difficulties associated with the application of the heat-balance method for this purpose. We developed a new method which solved this problem (Langensiepen et al. 2014) and applied it during four consecutive vegetation seasons for determining tiller transpiration rates in a wheat field with strong soil heterogeneity. The transpiration rates differed insignificantly between different field sections characterized by strong differences in physical soil conditions, regardless whether the crop was irrigated or supplied with variable rainwater. Tiller transpiration in a sheltered section was slightly reduced. Maximum leaf vapor conductance didn't differ among these different conditions, except under severe water stress conditions. Leaf water potential varied considerably during daily cycles under all circumstances. These responses are typical for plants with anisohydric behaviors which are characterized by small sensitivities of guard cells to critical leaf water potential thresholds and high photosynthetic productivity under absent or mild water stress. Recent studies conducted in Eucalyptus, tomato, and Arabidopsis plants have shown that the transition from mild to severe stress in anisohydric plants is marked by an increasing sensitivity of stomatal control to the transpiration rate. The results of this study demonstrate that this also seems to be the case for wheat. This practically implies that the parameterization of models calculating wheat canopy flux responses to soil heterogeneity patterns must not only account for the crop-type specific soil-vegetation pattern interaction under absent or mild stress, but also for additional mechanisms which kick in when water stress becomes severe. Langensiepen, M., Kupisch, M., Graf, A., Schmidt, M., Ewert, F. (2014) Improving the stem heat balance method for determining sap-flow in wheat. Agric. For. Met. 186: 34-42

  17. Steady state or non-steady state? Identifying driving mechanisms of oxygen isotope signatures of leaf transpiration in functionally distinct plant species

    Science.gov (United States)

    Dubbert, Maren; Kübert, Angelika; Cuntz, Matthias; Werner, Christiane

    2015-04-01

    Isotope techniques are widely applied in ecosystem studies. For example, isoflux models are used to separate soil evaporation from transpiration in ecosystems. These models often assume that plant transpiration occurs at isotopic steady state, i.e. that the transpired water shows the same isotopic signature as the source water. Yet, several studies found that transpiration did not occur at isotopic steady state, under both controlled and field conditions. Here we focused on identifying the internal and external factors which drive the isotopic signature of leaf transpiration. Using cavity ring-down spectroscopy (CRDS), the effect of both environmental variables and leaf physiological traits on δ18OT was investigated under controlled conditions. Six plant species with distinct leaf physiological traits were exposed to step changes in relative air humidity (RH), their response in δ18OT and gas exchange parameters and their leaf physiological traits were assessed. Moreover, two functionally distinct plant types (tree, i.e. Quercus suber, and grassland) of a semi-arid Mediterranean oak-woodland where observed under natural conditions throughout an entire growth period in the field. The species differed substantially in their leaf physiological traits and their turn-over times of leaf water. They could be grouped in species with fast (240 min.) turn-over times, mostly due to differences in stomatal conductance, leaf water content or a combination of both. Changes in RH caused an immediate response in δ18OT, which were similarly strong in all species, while leaf physiological traits affected the subsequent response in δ18OT. The turn-over time of leaf water determined the speed of return to the isotopic steady or a stable δ18OT value (Dubbert & Kübert et al., in prep.). Under natural conditions, changes in environmental conditions over the diurnal cycle had a huge impact on the diurnal development of δ18OT in both observed plant functional types. However, in

  18. Prediction Model of Greenhouse Eggplant Transpiration Rate Based on BP Neural Network%基于BP-NN的温室膜下滴灌茄子蒸腾速率预测模型

    Institute of Scientific and Technical Information of China (English)

    葛建坤; 李小平; 罗金耀

    2016-01-01

    通过田间试验,对温室膜下滴灌茄子冠层叶片蒸腾速率的变化规律进行了深入研究。通过分析温室内地面温度、相对湿度、植株冠层温度、气压、水面蒸发、太阳辐射等6个环境参数与茄子蒸腾速率的综合影响关系,确定了网络拓扑结构为6-9-1。并应用 MATLAB 软件,选择 Levenberg-Marquardt (L-M)优化算法,建立了基于 Back Propagation(BP)神经网络的温室膜下滴灌茄子蒸腾速率预测模型。经模型验证得出,BP 神经网络模型预测值与蒸腾速率实测值间拟合效果较好,平均相对误差为0.0298,达到预测精度要求。该研究成果对温室膜下滴灌作物需水规律及需水量研究具有较好的参考价值。%In order to reveal the law of crop transpiration in greenhouse,a field experiment on transpiration rate of greenhouse egg-plant with drip irrigation under mulch was taken in a Venlo type greenhouse in North China University of Water Resources and Elec-tric Power.Through the analysis on the combined influence between eggplant transpiration rate and 6 indoor environmental factors (greenhouse ground temperature,relative humidity,plant canopy temperature,air pressure,evaporation and solar radiation),topol-ogical structure of the model was discussed and determined (6-9-1).And a prediction model of greenhouse eggplant transpiration rate was established based on BP Neural network of L-M optimizing algorithm,by using MATLAB.After the model validation,the re-sults indicated that,the BP neural network prediction model has a high precision,the predicted value fits the measured value well, and average relative error is only 0.0298,which meets the precision requirement.The research result has a certain reference value to the study on crop water requirement in greenhouse with drip irrigation under mulch.

  19. Effects of Planting Density on Transpiration, Stem Flow and Interception for Two Clones Differing in Drought Tolerance in a High Productivity Eucalyptus Plantation in Brazil

    Science.gov (United States)

    Hubbard, R. M.; Hakemada, R.; Ferraz, S.

    2015-12-01

    Eucalypt plantations cover about 20 M hectares worldwide and expansion is expected to mainly occur in marginal growing areas where dry conditions may lead to water conflicts. One of the principal reasons for the expansion of Eucalyptus plantations is rapid wood growth but these forests also transpire large amounts of water. Genotype selection and planting density, are key factors regulating carbon and water tradeoffs at a stand scale, but few studies have examined these simultaneously especially in highly productive clonal plantations. Our goal in this study was to examine the effects of planting density on carbon and water interactions using a drought tolerant and drought sensitive eucalyptus clone. This work is part of a larger study (TECHS project - Tolerance of Eucalyptus Clones to Hydric and Thermal Stresses) and is located in a flat Oxisol in southeast of Brazil. A drought tolerant (E. grandis x E. camaldulensis (Grancam) and drought sensitive clone E. grandis x E. urophylla (Urograndis) were planted at four densities ranging from 600 to 3.000 stem ha-1. We measured transpiration using thermal heat dissipation probes, wood growth, canopy interception and stemflow during a full year (21 to 33 months old). Precipitation during the study period was 738 mm. Independently of genetics, growth increased with increasing density. Transpiration also increased with planting density and ranged from 515-595 mm at wider spacing to 735-978 mm at tighter spacing. Interception increased with planting density representing 18-22% of precipitation versus 13-14% in wider spacing while stem flow represented 2-5% in denser spacing and 1-2% at broader spacing. When density was higher than 1.250 and 1.750 stems ha-1 in Urograndis and Grancam clones, respectively, the water balance were negative. On a stand scale, results show both genetics and spacing can be used as silvicultural tools to better manage the tradeoff between wood growth and water consumption.

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

    Science.gov (United States)

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

    2011-04-01

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

  1. 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

    Science.gov (United States)

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

    2010-12-01

    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 and a maximum incoming solar radiation (Sin) 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.

  2. Influence of water relations and growth rate on plant element uptake and distribution

    Energy Technology Data Exchange (ETDEWEB)

    Greger, Maria [Stockholm Univ. (Sweden). Dept. of Botany

    2006-02-15

    Plant uptake of Ni, Sr, Mo, Cs, La, Th, Se, Cl and I was examined to determine how plant water relations and growth rate influence the uptake and distribution of these elements in the studied plants. The specific questions were how water uptake and growth rate influenced the uptake of various nuclides and how transpiration influenced translocation to the shoot. The knowledge gained will be used in future modelling of radionuclide leakage from nuclear waste deposits entering the ecosystem via plants. The plant studied was willow, Salix viminalis, a common plant in the areas suggested for waste disposal; since there can be clone variation, two different clones having different uptake properties for several other heavy metals were used. The plants were grown in nutrient solution and the experiments on 3-month-old plants were run for 3 days. Polyethylene glycol was added to the medium to decrease the water uptake rate, a fan was used to increase the transpiration rate, and different light intensities were used to produce different growth rates. Element concentration was analysed in roots and shoots. The results show that both the uptake and distribution of various elements are influenced in different ways and to various extents by water flow and plant growth rate, and that it is not possible from the chemical properties of these elements to know how they will react. However, in most cases increased growth rate diluted the concentration of the element in the tissue, reduced water uptake reduced the element uptake, while transpiration had no effect on the translocation of elements to the shoot. The clones did not differ in terms of either the uptake or translocation of the elements, except that I was not taken up and translocated to the shoot in one of the clones when the plant water flow or growth rate was too low. Not all of the elements were found in the plant in the same proportions as they had been added to the nutrient solution.

  3. Fruit load governs transpiration of olive trees.

    Science.gov (United States)

    Bustan, Amnon; Dag, Arnon; Yermiyahu, Uri; Erel, Ran; Presnov, Eugene; Agam, Nurit; Kool, Dilia; Iwema, Joost; Zipori, Isaac; Ben-Gal, Alon

    2016-03-01

    We tested the hypothesis that whole-tree water consumption of olives (Olea europaea L.) is fruit load-dependent and investigated the driving physiological mechanisms. Fruit load was manipulated in mature olives grown in weighing-drainage lysimeters. Fruit was thinned or entirely removed from trees at three separate stages of growth: early, mid and late in the season. Tree-scale transpiration, calculated from lysimeter water balance, was found to be a function of fruit load, canopy size and weather conditions. Fruit removal caused an immediate decline in water consumption, measured as whole-plant transpiration normalized to tree size, which persisted until the end of the season. The later the execution of fruit removal, the greater was the response. The amount of water transpired by a fruit-loaded tree was found to be roughly 30% greater than that of an equivalent low- or nonyielding tree. The tree-scale response to fruit was reflected in stem water potential but was not mirrored in leaf-scale physiological measurements of stomatal conductance or photosynthesis. Trees with low or no fruit load had higher vegetative growth rates. However, no significant difference was observed in the overall aboveground dry biomass among groups, when fruit was included. This case, where carbon sources and sinks were both not limiting, suggests that the role of fruit on water consumption involves signaling and alterations in hydraulic properties of vascular tissues and tree organs.

  4. Modelling the impact of the light regime on single tree transpiration based on 3D representations of plant architecture

    Science.gov (United States)

    Bittner, S.; Priesack, E.

    2012-04-01

    We apply a functional-structural model of tree water flow to single old-growth trees in a temperate broad-leaved forest stand. Roots, stems and branches are represented by connected porous cylinder elements further divided into the inner heartwood cylinders surrounded by xylem and phloem. Xylem water flow is simulated by applying a non-linear Darcy flow in porous media driven by the water potential gradient according to the cohesion-tension theory. The flow model is based on physiological input parameters such as the hydraulic conductivity, stomatal response to leaf water potential and root water uptake capability and, thus, can reflect the different properties of tree species. The actual root water uptake is calculated using also a non-linear Darcy law based on the gradient between root xylem water potential and rhizosphere soil water potential and by the simulation of soil water flow applying Richards equation. A leaf stomatal conductance model is combined with the hydrological tree and soil water flow model and a spatially explicit three-dimensional canopy light model. The structure of the canopy and the tree architectures are derived by applying an automatic tree skeleton extraction algorithm from point clouds obtained by use of a terrestrial laser scanner allowing an explicit representation of the water flow path in the stem and branches. The high spatial resolution of the root and branch geometry and their connectivity makes the detailed modelling of the water use of single trees possible and allows for the analysis of the interaction between single trees and the influence of the canopy light regime (including different fractions of direct sunlight and diffuse skylight) on the simulated sap flow and transpiration. The model can be applied at various sites and to different tree species, enabling the up-scaling of the water usage of single trees to the total transpiration of mixed stands. Examples are given to reveal differences between diffuse- and ring

  5. Transpiration and biomass production of the bioenergy crop Giant Knotweed Igniscum under various supplies of water and nutrients

    Directory of Open Access Journals (Sweden)

    Mantovani Dario

    2014-12-01

    Full Text Available Soil water availability, nutrient supply and climatic conditions are key factors for plant production. For a sustainable integration of bioenergy plants into agricultural systems, detailed studies on their water uses and growth performances are needed. The new bioenergy plant Igniscum Candy is a cultivar of the Sakhalin Knotweed (Fallopia sachalinensis, which is characterized by a high annual biomass production. For the determination of transpiration-yield relations at the whole plant level we used wicked lysimeters at multiple irrigation levels associated with the soil water availability (25, 35, 70, 100% and nitrogen fertilization (0, 50, 100, 150 kg N ha-1. Leaf transpiration and net photosynthesis were determined with a portable minicuvette system. The maximum mean transpiration rate was 10.6 mmol m-2 s-1 for well-watered plants, while the mean net photosynthesis was 9.1 μmol m-2 s-1. The cumulative transpiration of the plants during the growing seasons varied between 49 l (drought stressed and 141 l (well-watered per plant. The calculated transpiration coefficient for Fallopia over all of the treatments applied was 485.6 l kg-1. The transpiration-yield relation of Igniscum is comparable to rye and barley. Its growth performance making Fallopia a potentially good second generation bioenergy crop.

  6. [Study of the possibility of utilizing the transpired mositure condensate from sweet potato for growing plants in biological life support systems].

    Science.gov (United States)

    Derendiaeva, T A

    1976-01-01

    The effect of nonpurified condensate obtained during prolonged cultivation of batata in a sealed chamber upon batata cuttings and seedlings of garden cress, radish and Chinese cabbage was studied. It was shown that nonpurified condensate produced an inhibitory effect on the formation of roots in batata cuttings and on the growth of previously developed roots of batata cuttings and seedlings. The studies which used a chemical model of 3,4-dihydroxy phenylalanine indicated that the condensate contained biologically active substance of organic origin. However, only experiments with the real continuous culture of batata, using real dilutions of the condensate that depend on the size of the greenhouse and the amount of the nutrient solution would clarify wheather condensate of transpiration water of batata plants can be repeatedly utilized in life support systems.

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

    Science.gov (United States)

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

    2013-04-01

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

  8. Predictable 'meta-mechanisms' emerge from feedbacks between transpiration and plant growth and cannot be simply deduced from short-term mechanisms.

    Science.gov (United States)

    Tardieu, François; Parent, Boris

    2016-08-29

    Growth under water deficit is controlled by short-term mechanisms but, because of numerous feedbacks, the combination of these mechanisms over time often results in outputs that cannot be deduced from the simple inspection of individual mechanisms. It can be analysed with dynamic models in which causal relationships between variables are considered at each time-step, allowing calculation of outputs that are routed back to inputs for the next time-step and that can change the system itself. We first review physiological mechanisms involved in seven feedbacks of transpiration on plant growth, involving changes in tissue hydraulic conductance, stomatal conductance, plant architecture and underlying factors such as hormones or aquaporins. The combination of these mechanisms over time can result in non-straightforward conclusions as shown by examples of simulation outputs: 'over production of abscisic acid (ABA) can cause a lower concentration of ABA in the xylem sap ', 'decreasing root hydraulic conductance when evaporative demand is maximum can improve plant performance' and 'rapid root growth can decrease yield'. Systems of equations simulating feedbacks over numerous time-steps result in logical and reproducible emergent properties that can be viewed as 'meta-mechanisms' at plant level, which have similar roles as mechanisms at cell level.

  9. Stem girdling evidences a trade-off between cambial activity and sprouting and dramatically reduces plant transpiration due to feedback inhibition of photosynthesis and hormone signaling

    Directory of Open Access Journals (Sweden)

    Rosana eLópez

    2015-04-01

    Full Text Available The photosynthesis source-sink relationship in young Pinus canariensis seedlings was modified by stem girdling to investigate sprouting and cambial activity, feedback inhibition of photosynthesis, and stem and root hydraulic capacity. Removal of bark tissue showed a trade-off between sprouting and diameter growth. Above the girdle, growth was accelerated but the number of sprouts was almost negligible, whereas below the girdle the response was reversed. Girdling resulted in a sharp decrease in whole plant transpiration and root hydraulic conductance. The reduction of leaf area after girdling was strengthened by the high levels of ABA found in buds which pointed to stronger bud dormancy, preventing a new needle flush. Accumulation of sugars in leaves led to a coordinated reduction in net photosynthesis (AN and stomatal conductance (gS in the short term, but later (gS below 0.07 mol m-2 s-1 AN decreased faster. The decrease in maximal efficiency of photosystem II (FV/FM and the operating quantum efficiency of photosystem II (ΦPSII in girdled plants could suggest photoprotection of leaves, as shown by the vigorous recovery of AN and ΦPSII after reconnection of the phloem. Stem girdling did not affect xylem embolism but increased stem hydraulic conductance above the girdle. This study shows that stem girdling affects not only the carbon balance, but also the water status of the plant.

  10. Stem girdling evidences a trade-off between cambial activity and sprouting and dramatically reduces plant transpiration due to feedback inhibition of photosynthesis and hormone signaling.

    Science.gov (United States)

    López, Rosana; Brossa, Ricard; Gil, Luis; Pita, Pilar

    2015-01-01

    The photosynthesis source-sink relationship in young Pinus canariensis seedlings was modified by stem girdling to investigate sprouting and cambial activity, feedback inhibition of photosynthesis, and stem and root hydraulic capacity. Removal of bark tissue showed a trade-off between sprouting and diameter growth. Above the girdle, growth was accelerated but the number of sprouts was almost negligible, whereas below the girdle the response was reversed. Girdling resulted in a sharp decrease in whole plant transpiration and root hydraulic conductance. The reduction of leaf area after girdling was strengthened by the high levels of abscisic acid found in buds which pointed to stronger bud dormancy, preventing a new needle flush. Accumulation of sugars in leaves led to a coordinated reduction in net photosynthesis (AN) and stomatal conductance (gS) in the short term, but later (gS below 0.07 mol m(-2) s(-1)) AN decreased faster. The decrease in maximal efficiency of photosystem II (FV/FM) and the operating quantum efficiency of photosystem II (ΦPSII) in girdled plants could suggest photoprotection of leaves, as shown by the vigorous recovery of AN and ΦPSII after reconnection of the phloem. Stem girdling did not affect xylem embolism but increased stem hydraulic conductance above the girdle. This study shows that stem girdling affects not only the carbon balance, but also the water status of the plant.

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

    Science.gov (United States)

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

    2012-04-01

    The stomatal control of transpiration is one of the major strategies by which plants cope with water stress. Here, we investigated the genetic architecture of the rootstock control of scion transpiration-related traits over a period of 3 yr. The rootstocks studied were full sibs from a controlled interspecific cross (Vitis vinifera cv. Cabernet Sauvignon × Vitis riparia cv. Gloire de Montpellier), onto which we grafted a single scion genotype. After 10 d without stress, the water supply was progressively limited over a period of 10 d, and a stable water deficit was then applied for 15 d. Transpiration rate was estimated daily and a mathematical curve was fitted to its response to water deficit intensity. We also determined δ(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. © 2012 INRA. New Phytologist © 2012 New Phytologist Trust.

  12. Impact of photosynthesis and transpiration on nitrogen removal in constructed wetlands

    Institute of Scientific and Technical Information of China (English)

    LUO Weiguo; WANG Shihe; HUANG Juan; YAN Lu; HUANG Jun

    2007-01-01

    To determine the impact of photosynthesis and transpiration on nitrogen removal in wetlands,an artificial wetland planted with reeds was constructed to treat highly concentrated domestic wastewater.Under different meteorological and hydraulic conditions,the daily changes of photosynthesis and transpiration of reeds,as well as nitrogen removal efficiency were measured.It was found that net photosynthesis rate per unit leaf area was maintained on a high Photon Flux Density was high during the day.Meanwhile,TN and NH4+-N removal efficiency rose to 79.6% and 89.6%,respectively-the maximum values observed in the test.Correlation coefficient analysis demonstrated a positive correlation among photon flux density,net photosynthetic rate,transpiration rate,and TN and NH4+-N removal efficiency.In contrast,there was a negative correlation between stomatal conductance and TN and NH4+-N removal efficiency.Results suggest that the photosynthesis and transpiration of wetland plants have a great impact on nitrogen removal efficiency of wetlands,which can be enhanced by an increase in the photosynthesis and transpiration rate.In addition,the efficiency of water usage by reeds and nitrogen removal efficiency could be affected by the water level in wetlands;a higher level boosts nitrogen removal efficiency.

  13. Compensating effect of sap velocity for stand density leads to uniform hillslope-scale forest transpiration across a steep valley cross-section

    Science.gov (United States)

    Renner, Maik; Hassler, Sibylle; Blume, Theresa; Weiler, Markus; Hildebrandt, Anke; Guderle, Marcus; Schymanski, Stan; Kleidon, Axel

    2016-04-01

    Roberts (1983) found that forest transpiration is relatively uniform across different climatic conditions and suggested that forest transpiration is a conservative process compensating for environmental heterogeneity. Here we test this hypothesis at a steep valley cross-section composed of European Beech in the Attert basin in Luxemburg. We use sapflow, soil moisture, biometric and meteorological data from 6 sites along a transect to estimate site scale transpiration rates. Despite opposing hillslope orientation, different slope angles and forest stand structures, we estimated relatively similar transpiration responses to atmospheric demand and seasonal transpiration totals. This similarity is related to a negative correlation between sap velocity and site-average sapwood area. At the south facing sites with an old, even-aged stand structure and closed canopy layer, we observe significantly lower sap velocities but similar stand-average transpiration rates compared to the north-facing sites with open canopy structure, tall dominant trees and dense understorey. This suggests that plant hydraulic co-ordination allows for flexible responses to environmental conditions leading to similar transpiration rates close to the water and energy limits despite the apparent heterogeneity in exposition, stand density and soil moisture. References Roberts, J. (1983). Forest transpiration: A conservative hydrological process? Journal of Hydrology 66, 133-141.

  14. 蚕豆(Vicia faba L.)叶片蒸腾速率的因子分析%Analysis of the Factors Affecting the Transpiration Rate of Vicia faba L. Leaves

    Institute of Scientific and Technical Information of China (English)

    鲍思伟

    2001-01-01

    利用LI-1600稳态气孔计测定了蚕豆叶片蒸腾速率的日变化,以及水分胁迫下蒸腾速率的变化,探讨了环境因子对蚕豆叶片蒸腾速率的影响.结果表明,光量子通量密度是影响蒸腾速率的主要气象因子,土壤含水量影响叶片相对含水量,并通过气孔扩散阻力来影响蒸腾速率.%By using LI-1600 steady state porometer,the transpiration changes of the Vicia faba L.leaves were determined through a day and under the condition of the water stress,in order to evaluate the effect of environmental factors on the transpiration rate of the Vicia faba leaves.The result indicated that PFD is the principal meteorological factor influencing transpiration.The soil water content influenced the relative water content of leaf leaves,and also influenced the transpiration by stoma diffusing resistance.

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

    Science.gov (United States)

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

    1984-01-01

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

  16. Connections between groundwater flow and transpiration partitioning

    Science.gov (United States)

    Maxwell, Reed M.; Condon, Laura E.

    2016-07-01

    Understanding freshwater fluxes at continental scales will help us better predict hydrologic response and manage our terrestrial water resources. The partitioning of evapotranspiration into bare soil evaporation and plant transpiration remains a key uncertainty in the terrestrial water balance. We used integrated hydrologic simulations that couple vegetation and land-energy processes with surface and subsurface hydrology to study transpiration partitioning at the continental scale. Both latent heat flux and partitioning are connected to water table depth, and including lateral groundwater flow in the model increases transpiration partitioning from 47 ± 13 to 62 ± 12%. This suggests that lateral groundwater flow, which is generally simplified or excluded in Earth system models, may provide a missing link for reconciling observations and global models of terrestrial water fluxes.

  17. Leaf energy balance and transpirational relationships of tulip poplar (Liriodendron tulipifera)

    Energy Technology Data Exchange (ETDEWEB)

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

    1976-10-01

    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 stomatal relationships with environmental and plant morphological variables, determine and assess the relative importance of factors affecting transpiration and leaf energy balance of a mature tulip poplar, examine and describe the diurnal kinetics of transpiration and leaf energy balance under forest conditions, and examine and develop equations describing these processes and relationships. Tulip poplar leaves were examined at three crown heights. Stomatal distribution, density, and dimensions were measured, then these data were used to predict leaf diffusion layer resistance. Stomatal dimensions decreased with crowned height while stomatal density increased, but neither varied over individual leaf surfaces. Numbers of stomata per leaf were constant throughout the crown. Calculated transpiration rates were compared with stomatal diffusion resistance, leaf xylem water potential, and environmental parameters. Diurnal leaf heat loss, water stress, and stomatal resistance measurements followed the diurnal variation of the radiation absorbed by the leaf. Heat loss by radiation, evaporation, and convection varied with crown height in response to variations in stomatal diffusion resistance, transpiration, vapor pressure deficit, leaf temperature, and wind speed.

  18. Gas exchange rates, plant height, yield components, and productivity of upland rice as affected by plant regulators

    Directory of Open Access Journals (Sweden)

    Rita de Cássia Félix Alvarez

    2012-10-01

    Full Text Available The objective of this work was to evaluate gas exchange rates, plant height, yield components, and productivity of upland rice, as affected by type and application time of plant growth regulators. A randomized block design, in a 4x2 factorial arrangement, with four replicates was used. Treatments consisted of three growth regulators (mepiquat chloride, trinexapac-ethyl, and paclobutrazol, besides a control treatment applied at two different phenological stages: early tillering or panicle primordial differentiation. The experiment was performed under sprinkler-irrigated field conditions. Net CO2 assimilation, stomatal conductance, plant transpiration, and water-use efficiency were measured four times in Primavera upland rice cultivar, between booting and milky grain phenophases. Gas exchange rates were neither influenced by growth regulators nor by application time. There was, however, interaction between these factors on the other variables. Application of trinexapac-ethyl at both tillering and differentiation stages reduced plant height and negatively affected yield components and rice productivity. However, paclobutrazol and mepiquat chloride applied at tillering, reduced plant height without affecting rice yield. Mepiquat chloride acted as a growth stimulator when applied at the differentiation stage, and significantly increased plant height, panicle number, and grain yield of upland rice.

  19. 4个椰子品种光合、蒸腾作用日变化特征及影响因素%Daily Changes of Photosynthesis and Transpiration Rate of Four Cultivars of Coconut and the Influencing Factors

    Institute of Scientific and Technical Information of China (English)

    宫璇; 张如莲; 曹红星; 孙程旭; 李正民

    2011-01-01

    Yellow Dwarf Coconut, Aromatic Dwarf Coconut, Hainan Tall Coconut and Wenye 78F1 at the stage of active fruiting were used as the research materials. The daily changes of transpiration rate, net photosynthesis rate and the interaction of influencing factors as temperature, humidity, intensity of illumination, CO2 concentration were studied. The result revealed that the net photosynthesis rate and transpiration rate of different varieties were with similar two-peak changing tendency, Hainan Tall Coconut with higher transpiration rate and net photosynthesis rate than Aromatic Dwarf Coconut and Wenye 78F1, Yellow Dwarf Coconut with the lowest values compared to the others. The eonelation analysis revealed that the net photosynthesis rate was mainly influenced by the intensity of illumination and leaf temperature. Air humidity and leaf temperature were the main factors that affected the transpiration rate.%以结果盛期的黄矮椰子、香水椰子、本地高种椰子、文椰78F14个椰子品种为研究对象,对椰子叶片的光合作用、蒸腾作用的日变化规律及温度、湿度、光合有效辐射和CO2浓度等环境因子之间的互作进行研究.结果表明,不同椰子品种的光合速率和蒸腾速率日进程表现为明显的双峰型日变化,本地高种椰子的光合速率和蒸腾速率都比较高,香水椰子和文椰78F1居中,黄矮椰子最低.光合有效辐射、叶片温度对椰子光合速率有重要影响,空气湿度和叶片温度是影响蒸腾速率的重要环境因子.

  20. A direct measurement of the stable isotopes of transpired water vapor in a northern Michigan forest

    Science.gov (United States)

    Aron, P.; Poulsen, C. J.; Fiorella, R.

    2016-12-01

    The stable isotopes of oxygen and hydrogen in water vapor track hydrologic processes as phase changes of water preferentially partition heavy isotopes (18O and 2H) into the condensate and light isotopes (16O and 1H) into the vapor phase. As a result, the isotopic composition of water vapor can be used to identify water fluxes and cycling through natural environments. Forest water vapor is comprised of terrestrial (evaporation and transpiration) and atmospheric (tropospheric mixing, precipitation, and condensation) components. Within the isotopic record of forest water vapor, stable isotopes of transpired water (δT) comprise an important component but is typically either assumed to be non-fractionating or estimated indirectly. However, on small time scales (minutes to hours), non-steady state forest systems experience isotopic enrichment during early morning and late afternoon when transpiration rates are low. We deployed two Picarro Cavity Ring-Down spectrometers (L2120-i and L2130-i, respectively) in the University of Michigan Biological Station (UMBS) forest near Pellston, MI to measure the isotopic composition of near-surface ambient water vapor and the transpired vapor component directly. Both ambient and transpired water vapor were measured at three heights above the forest floor (2, 10, and 20 m) during August 2016. To measure species-specific water use, δT was measured on red maple (Acer rubrum) and northern red oak (Quercus rubra), two of the dominant tree types in the UMBS forest. This work represents the first direct measurement of δT in the UMBS forest and will help decouple local and species-specific hydrologic cycling. Beyond UMBS, this measurement will allow for a better understanding of species-specific plant hydraulics and help identify when the steady state approximation of transpiration is valid, which can be used to study water use and forest health.

  1. Steady streamwise transpiration control in turbulent pipe flow

    CERN Document Server

    Gómez, F; Rudman, M; Sharma, AS; McKeon, BJ

    2016-01-01

    A study of the the main features of low- and high amplitude steady streamwise wall transpiration applied to pipe flow is presented. The effect of the two transpiration parameters, amplitude and wavenumber, on the flow have been investigated by means of direct numerical simulation at a moderate turbulent Reynolds number. The behaviour of the three identified mechanisms that act in the flow: modification of Reynolds shear stress, steady streaming and generation of non-zero mean streamwise gradients, have been linked to the transpiration parameters. The observed trends have permitted the identification of wall transpiration configurations able to reduce or increase the overall flow rate in -36.1% and 19.3% respectively. A resolvent analysis has been carried out to obtain a description of the reorganization of the flow structures induced by the transpiration.

  2. Effect of different soil water potential on leaf transpiration and on stomatal conductance in poinsettia

    Directory of Open Access Journals (Sweden)

    Jacek S. Nowak

    2013-12-01

    Full Text Available Euphorbia pulcherrima Wild.'Lilo' was grown in containers in 60% peat, 30% perlite and 10% clay (v/v mixture, with different irrigation treatments based on soil water potential. Plants were watered at two levels of drought stress: -50kPa or wilting. The treatments were applied at different stages of plant development for a month or soil was brought to the moisture stress only twice. Additionally, some plants were watered at -50 kPa during the entire cultivation period while the control plants were watered at -5kPa. Plants were also kept at maximum possible moisture level (watering at -0,5kPa or close to it (-1.OkPa through the entire growing period. Soil water potential was measured with tensiometer. Drought stress applied during entire cultivation period or during the flushing stage caused significant reduction in transpiration and conductance of leaves. Stress applied during bract coloration stage had not as great effect on the stomatal conductance and transpiration of leaves as the similar stress applied during the flushing stage. High soil moisture increased stomatal conductance and transpiration rate, respectively by 130% and 52% (flushing stage, and 72% and 150% (bract coloration stage at maximum, compared to the control.

  3. Stem heat balance method to estimate transpiration of young orange and mango plants Balanço de calor caulinar para estimativa da transpiração de plantas jovens de laranja e manga

    Directory of Open Access Journals (Sweden)

    Lucas M. Vellame

    2010-01-01

    Full Text Available The present study had as its main objective the evaluation of the heat balance method in young orange and mango plants under protected environment. The work was carried out at Embrapa Cassava and Tropical Fruits, Cruz das Almas, BA. Later on, estimates of sap flow were conducted for two mango plants cultivated in pots of 15 and 50 L installed on weighting platforms of 45 and 140 kg; sap flow was determined in three orange plants, two of which were also installed on weighing platforms. The values of sap flow were compared to the transpiration measured by lysimeters at integrated intervals of 1, 2, 4 and 24 h. The heat balance method showed good precision for estimating daily transpiration (R² = 0.95 and R² = 0.90, accompaning the availability of energy in the system, underestimating on average 4.6% of the daily transpiration in orange plants and overestimating in about 0.3% the daily transpiration of mango plants under conditions of good water supply. The heat balance method underestimated by 16% the transpiration in orange under conditions of water deficit.Com o presente estudo se objetivou avaliar o método de balanço de calor em plantas jovens de laranja e manga em ambiente protegido. O trabalho foi conduzido na Embrapa Mandioca e Fruticultura, Cruz das Almas, BA. Realizaram-se estimativas de fluxo de seiva em duas plantas de manga plantadas em vasos de 15 e 50 L, instalados sobre plataformas de pesagem de 45 e 140 kg; posteriormente, o fluxo de seiva foi determinado em três plantas de laranja, duas também instaladas em lisímetros de pesagem. Os valores de fluxo de seiva obtidos foram comparados com a transpiração medida pelos lisímetros em intervalos de integração de 1, 2, 4 e 24 h. O método do balanço de calor mostrou-se preciso na estimativa da transpiração diária (R² = 0,95 e R² = 0,90, que acompanhou a disponibilidade de energia do sistema, subestimando em média, 4,6% a transpiração diária em plantas de laranja e

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

    Science.gov (United States)

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

    2013-07-01

    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.

  5. Growth and transpiration of Japanese cedar (Cryptomeria japonica) and Hinoki cypress (Chamaecyparis obtusa) seedlings in response to soil water content.

    Science.gov (United States)

    Nagakura, Junko; Shigenaga, Hidetoshi; Akama, Akio; Takahashi, Masamichi

    2004-11-01

    To investigate the effects of soil water content on growth and transpiration of Japanese cedar (Cryptomeria japonica D. Don) and Hinoki cypress (Chamaecyparis obtusa (Siebold et Zucc.) Endl.), potted seedlings were grown in well-watered soil (wet treatment) or in drying soil (dry treatment) for 12 weeks. Seedlings in the wet treatment were watered once every 2 or 3 days, whereas seedlings in the dry treatment were watered when soil water content (Theta; m3 m(-3)) reached 0.30, equivalent to a soil matric potential of -0.06 MPa. From Weeks 7 to 12 after the onset of the treatments, seedling transpiration was measured by weighing the potted seedlings. After the last watering, changes in transpiration rate during soil drying were monitored intensely. The dry treatment restricted aboveground growth but increased biomass allocation to the roots in both species, resulting in no significant treatment difference in whole-plant biomass production. The species showed similar responses in relative growth rate (RGR), net assimilation rate (NAR) and shoot mass ratio (SMR) to the dry treatment. Although NAR did not change significantly in either C. japonica or C. obtusa as the soil dried, the two species responded differently to the dry treatment in terms of mean transpiration rate (E) and water-use efficiency (WUE), which are parameters that relate to NAR. In the dry treatment, both E and WUE of C. japonica were stable, whereas in C. obtusa, E decreased and WUE increased (E and WUE counterbalanced to maintain a constant NAR). Transpiration rates were lower in C. obtusa seedlings than in C. japonica seedlings, even in well-watered conditions. During soil drying, the transpiration rate decreased after Theta reached about 0.38 (-0.003 MPa) in C. obtusa and 0.32 (-0.028 MPa) in C. japonica. We conclude that C. obtusa has more water-saving characteristics than C. japonica, particularly when water supply is limited.

  6. Efeitos de produtos químicos na transpiração e no potencial da água de seringueira (Hevea brasiliensis Muell . Arg. cv.RRIM 600 Effects of chemicals on transpiration and water potential of rubber plant (Hevea brasiliensis Muell . Arg. cv.RRIM 600

    Directory of Open Access Journals (Sweden)

    P.R.C. Castro

    1984-01-01

    Full Text Available Um experimento foi realizado em condições de campo, em Piracicaba (SP, visando avali ar a eficiência de diferentes produtos químicos, em aplicação foliar, na taxa transpiratória e no potencial da água de folhas das plantas de seringueira (He Yea brasiliens is cv. RRIM 600 com 1,5 ano de idade. Os tratamentos utilizados foram: polissulfetc, de polietileno (Good-rite peps 0,04 %, oxietileno docosanol (Oed green 2%, caulim (silicato de aluminio 3%, e atrazine 50 ppm, alem do controle. Através do método da pesagem rápida de folhas desta cadas, com balança de torço tipo Jung, verificou-se a perda de água pelas plantas de seringueira foi restringida significativamente pelo anti-transpirante metabólico (atrazine com relação ao controle, aos formadores de filme e ao refletor. Polissulfeto de polietileno apresentou as menores amplitudes de variações na taxa respiratória. Atrazine também promoveu a manutenção do potencial da água das folhas mais alto (-7,8 bars com relação ao controle (-14,8 bars, de acordo com determinações efe tuadas através da Câmara de Scholander.This research deals with the effects of chemicals on transpiration and water potential of Hevea brasiliens is cv. RRIM 600 on plants, with 1,5 year old, under field conditions. Rubber plants were sprayed with poliethylen e polys ulfite 0,04%, oxyethylen e docosanol 2%, kaolin 3%, atrazine 50 ppm, and check. A higher efficiency again st water loss was observed for atrazine (10,9 mg water . cm-2 . min-1 in relation to check plants (14,6 mg water . cm . min-1 at the maximum transpiration rate average. Polyethylen e polysulfite presented lower amplitude variation of the transpiration rates during the measurements at the day period. Atrazine promoted the maint enance of a higher water potential (-7,8 bars compared to check treatment (-14,8 bars.

  7. Expression of Arabidopsis hexokinase in citrus guard cells controls stomatal aperture and reduces transpiration

    Directory of Open Access Journals (Sweden)

    Nitsan eLugassi

    2015-12-01

    Full Text Available Hexokinase (HXK is a sugar-phosphorylating enzyme involved in sugar-sensing. It has recently been shown that HXK in guard cells mediates stomatal closure and coordinates photosynthesis with transpiration in the annual species tomato and Arabidopsis. To examine the role of HXK in the control of the stomatal movement of perennial plants, we generated citrus plants that express Arabidopsis HXK1 (AtHXK1 under KST1, a guard cell-specific promoter. The expression of KST1 in the guard cells of citrus plants has been verified using GFP as a reporter gene. The expression of AtHXK1 in the guard cells of citrus reduced stomatal conductance and transpiration with no negative effect on the rate of photosynthesis, leading to increased water-use efficiency. The effects of light intensity and humidity on stomatal behavior were examined in rooted leaves of the citrus plants. The optimal intensity of photosynthetically active radiation and lower humidity enhanced stomatal closure of AtHXK1-expressing leaves, supporting the role of sugar in the regulation of citrus stomata. These results suggest that HXK coordinates photosynthesis and transpiration and stimulates stomatal closure not only in annual species, but also in perennial species.

  8. Subtropical Modern Greenhouse Cucumber Canopy Transpiration Under Summer Climate Condition

    Institute of Scientific and Technical Information of China (English)

    LUO Wei-hong; WANG Xiao-han; DING Wei-min; CHEN Yu-qing; DAI Jian-feng

    2002-01-01

    Greenhouse canopy transpiration not only has effects on greenhouse air temperature and humidity, but also is important for determining the set-point of fertigation. In this study, Penman-Monteith equation was used to calculate the greenhouse cucumber canopy transpiration under summer climate condition.The effects of greenhouse environmental factors on canopy transpiration were analyzed based on the measurements of greenhouse microclimate factors and canopy transpiration. The results showed that Penman-Monteith equation was reliable and robust in estimating greenhouse cucumber canopy transpiration under summer climate condition. Greenhouse cucumber canopy transpiration rate increased linearly with the increase of net radiation and water vapor pressure deficit (VPD) above the canopy. But the maximum value of the canopy transpiration rate occurred at the same time as that of VPD whereas about two hours later than that of net radiation. Based on the results, it was concluded that in addition to radiation, air humidity should also be considered when determine the set-point of fertigation.

  9. Forest Transpiration: Resolving Species-Specific Root Water Uptake Patterns

    Science.gov (United States)

    Blume, T.; Heidbuechel, I.; Simard, S.; Guntner, A.; Weiler, M.; Stewart, R. D.

    2016-12-01

    Transpiration and its spatio-temporal variability are still not fully understood, despite their importance for the global water cycle. This is in part due to our inability to measure transpiration comprehensively. Transpiration is usually either estimated with empirical equations based on climatic variables and crop factors, by measuring sap velocities, estimating sap wood area and scaling up to the forest stand based on a number of assumptions or by measuring the integral signal across a footprint with eddy flux towers. All these methods are focused on the cumulated loss of water to the atmosphere and do not provide information on where this water is coming from. In this study, spatio-temporal variability of root water uptake was investigated in a forest in the northeastern German lowlands. The soils are sandy and the depth of the unsaturated zone ranges from 1 to 30 m. We estimated root water uptake from different soil depths, from 0.1 m down to 2 m, based on diurnal fluctuations in soil moisture content during rain-free days. The 15 field sites cover different topographic positions and forest stands: 4 pure stands of both mature and young beech and pine and 9 mixed stands. The resulting daily data set of root water uptake shows that the forest stands differ in total amounts as well as in uptake depth distributions. Temporal dynamics of signal strength within the profile suggest a locally shifting spatial distribution of uptake that changes with water availability. The relationship of these depth-resolved uptake rates to overall soil water availability varies considerably between tree species. Using the physically-based soil hydrological model HYDRUS we investigated to what extent the observed patterns in uptake can be related to soil physical relationships alone and where tree species-specific aspects come into play. We furthermore used the model to test assumptions and estimate uncertainties of this soil moisture based estimation of plant water uptake. The

  10. Quality Protein Maize Response to Nitrogen Rate and Plant Density ...

    African Journals Online (AJOL)

    Quality Protein Maize Response to Nitrogen Rate and Plant Density in the Guinea Savanna Zone of Ghana. ... protein maize (Zea mays L.) hybrid to plant density and nitrogen (N) fertilizer. ... Optimal N rate was not affected by plant density.

  11. Wind-induced leaf transpiration

    Science.gov (United States)

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

    2015-12-01

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

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

    DEFF Research Database (Denmark)

    Hebbern, Christopher Alan; Laursen, Kristian Holst; Ladegaard, Anne Hald

    2009-01-01

    To investigate if latent manganese (Mn) deficiency leads to increased transpiration, barley plants were grown for 10 weeks in hydroponics with daily additions of Mn in the low nM range. The Mn-starved plants did not exhibit visual leaf symptoms of Mn deficiency, but Chl a fluorescence measurements...

  13. Mathematical Modeling of Dual Intake Transparent Transpired Solar Collector

    OpenAIRE

    Thomas Semenou; Rousse, Daniel R.; Brice Le Lostec; Hervé F. Nouanegue; Pierre-Luc Paradis

    2015-01-01

    Nowadays, in several types of commercial or institutional buildings, a significant rise of transpired solar collectors used to preheat the fresh air of the building can be observed. Nevertheless, when the air mass flow rate is low, the collector efficiency collapses and a large amount of energy remains unused. This paper presents a simple yet effective mathematical model of a transparent transpired solar collector (TTC) with dual intake in order to remove stagnation problems in the plenum and...

  14. Water, heat, and airborne pollutants effects on transpiration of urban trees

    Energy Technology Data Exchange (ETDEWEB)

    Wang Hua [State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085 (China); Ouyang Zhiyun, E-mail: zyouyang@rcees.ac.cn [State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085 (China); Chen Weiping; Wang Xiaoke; Zheng Hua; Ren Yufen [State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085 (China)

    2011-08-15

    Transpiration rates of six urban tree species in Beijing evaluated by thermal dissipation method for one year were correlated to environmental variables in heat, water, and pollutant groups. To sort out colinearity of the explanatory variables, their individual and joint contributions to variance of tree transpiration were determined by the variation and hierarchical partitioning methods. Majority of the variance in transpiration rates was associated with joint effects of variables in heat and water groups and variance due to individual effects of explanatory group were in comparison small. Atmospheric pollutants exerted only minor effects on tree transpiration. Daily transpiration rate was most affected by air temperature, soil temperature, total radiation, vapor pressure deficit, and ozone. Relative humidity would replace soil temperature when factors influencing hourly transpiration rate was considered. - Highlights: > Heat, water, pollutants effect on transpiration was evaluated by partitioning method. > Urban tree transpiration was mainly affected by combined effects of these variables. > The heat and water variables affected transpiration of urban trees. > The urban air pollution merely acts as an antagonistic factor. - Heat and water related environmental variables affected transpiration of urban trees and ozone was an added yet minor stress factor.

  15. Rising CO2 widens the transpiration-photosynthesis optimality space

    Science.gov (United States)

    de Boer, Hugo J.; Eppinga, Maarten B.; Dekker, Stefan C.

    2016-04-01

    Stomatal conductance (gs) and photosynthetic biochemistry, typically expressed by the temperature-adjusted maximum rates of carboxylation (V cmax) and electron transport (Jmax), are key traits in land ecosystem models. Contrary to the many approaches available for simulating gs responses, the biochemical parameters V cmax and Jmax are often treated as static traits in ecosystem models. However, observational evidence indicates that V cmax and Jmax respond to persistent changes in atmospheric CO2. Hence, ecosystem models may be improved by incorporating coordinated responses of photosynthetic biochemistry and gs to atmospheric CO2. Recently, Prentice et al. (2014) proposed an optimality framework (referred to as the Prentice framework from here on) to predict relationships between V cmax and gs based on Fick's law, Rubisco-limited photosynthesis and the carbon costs of transpiration and photosynthesis. Here we show that this framework is, in principle, suited to predict CO2-induced changes in the V cmax -gs relationships. The framework predicts an increase in the V cmax:gs-ratio with higher atmospheric CO2, whereby the slope of this relationship is determined by the carbon costs of transpiration and photosynthesis. For our empirical analyses we consider that the carbon cost of transpiration is positively related to the plant's Huber value (sapwood area/leaf area), while the carbon cost of photosynthesis is positively related to the maintenance cost of the photosynthetic proteins. We empirically tested the predicted effect of CO2 on the V cmax:gs-ratio in two genotypes of Solanum dulcamara (bittersweet) that were grown from seeds to maturity under 200, 400 and 800 ppm CO2 in walk-in growth chambers with tight control on light, temperature and humidity. Seeds of the two Solanum genotypes were obtained from two distinct natural populations; one adapted to well-drained sandy soil (the 'dry' genotype) and one adapted to poorly-drained clayey soil (the 'wet' genotype

  16. Effect of a short and severe intermittent drought on transpiration, seed yield components, and harvest index in four landraces of bambara groundnut

    DEFF Research Database (Denmark)

    Jørgensen, Søren Thorndal; Ntundu, W.H.; Ouédraogo, M.

    2011-01-01

    to soil drying. The high soil water thresholds for the reduction of transpiration rate and gs of bambara groundnuts indicate their great sensitivity in the stomatal control over plant water loss during soil drying. Even though the shoot dry weight at maturity was hardly affected by DS, seed yield, seed......Drought is a major constraint to crop production worldwide and landraces are one of the important genetic resources to crop improvement in the dry areas. The objective of this study was to investigate transpiration and yield responses of bambara groundnut (Vigna subterranea L. Verdc.) landraces......% of pot holding capacity until seed maturity or drought-stressed (DS) in the period from 76 to 85 days after sowing (flowering and early podding stage). During drought, although the total water use differed among the four landraces, transpiration rate and stomatal conductance (gs) responded similarly...

  17. Impact of Leaf Traits on Temporal Dynamics of Transpired Oxygen Isotope Signatures and Its Impact on Atmospheric Vapor.

    Science.gov (United States)

    Dubbert, Maren; Kübert, Angelika; Werner, Christiane

    2017-01-01

    Oxygen isotope signatures of transpiration (δ E ) are powerful tracers of water movement from plant to global scale. However, a mechanistic understanding of how leaf morphological/physiological traits effect δ E is missing. A laser spectrometer was coupled to a leaf-level gas-exchange system to measure fluxes and isotopic signatures of plant transpiration under controlled conditions in seven distinct species (Fagus sylvatica, Pinus sylvestris, Acacia longifolia, Quercus suber, Coffea arabica, Plantago lanceolata, Oxalis triangularis). We analyzed the role of stomatal conductance (gs ) and leaf water content (W) on the temporal dynamics of δ E following changes in relative humidity (rH). Changes in rH were applied from 60 to 30% and from 30 to 60%, which is probably more than covering the maximum step changes occurring under natural conditions. Further, the impact of gs and W on isotopic non-steady state isofluxes was analyzed. Following changes in rH, temporal development of δ E was well described by a one-pool modeling approach for most species. Isofluxes of δ E were dominantly driven by stomatal control on E, particularly for the initial period of 30 min following a step change. Hence, the deviation of isofluxes from isotopic steady state can be large, even though plants transpire near to isotopic steady state. Notably, not only transpiration rate and stomatal conductance, but also the leaf traits stomatal density (as a measure of gmax) and leaf water content are significantly related to the time constant (τ) and non-steady-state isofluxes. This might provide an easy-to-access means of a priori assumptions for the impact of isotopic non-steady-state transpiration in various ecosystems. We discuss the implications of our results from leaf to ecosystem scale.

  18. Impact of Leaf Traits on Temporal Dynamics of Transpired Oxygen Isotope Signatures and Its Impact on Atmospheric Vapor

    Science.gov (United States)

    Dubbert, Maren; Kübert, Angelika; Werner, Christiane

    2017-01-01

    Oxygen isotope signatures of transpiration (δE) are powerful tracers of water movement from plant to global scale. However, a mechanistic understanding of how leaf morphological/physiological traits effect δE is missing. A laser spectrometer was coupled to a leaf-level gas-exchange system to measure fluxes and isotopic signatures of plant transpiration under controlled conditions in seven distinct species (Fagus sylvatica, Pinus sylvestris, Acacia longifolia, Quercus suber, Coffea arabica, Plantago lanceolata, Oxalis triangularis). We analyzed the role of stomatal conductance (gs) and leaf water content (W) on the temporal dynamics of δE following changes in relative humidity (rH). Changes in rH were applied from 60 to 30% and from 30 to 60%, which is probably more than covering the maximum step changes occurring under natural conditions. Further, the impact of gs and W on isotopic non-steady state isofluxes was analyzed. Following changes in rH, temporal development of δE was well described by a one-pool modeling approach for most species. Isofluxes of δE were dominantly driven by stomatal control on E, particularly for the initial period of 30 min following a step change. Hence, the deviation of isofluxes from isotopic steady state can be large, even though plants transpire near to isotopic steady state. Notably, not only transpiration rate and stomatal conductance, but also the leaf traits stomatal density (as a measure of gmax) and leaf water content are significantly related to the time constant (τ) and non-steady-state isofluxes. This might provide an easy-to-access means of a priori assumptions for the impact of isotopic non-steady-state transpiration in various ecosystems. We discuss the implications of our results from leaf to ecosystem scale. PMID:28149303

  19. Photosynthesis-transpiration coupling model at canopy scale in terrestrial ecosystem

    Institute of Scientific and Technical Information of China (English)

    REN; Chuanyou; YU; Guirui; WANG; Qiufeng; GUAN; Dexin

    2005-01-01

    At the hypothesis of big leaf, an ecosystem photosynthesis-transpiration coupling cycle model was established by the scaled SMPT-SB model from single leaf to canopy, and model parameterization methods were discussed. Through simulating the canopy light distribution, canopy internal conductance to CO2 can be scaled from single leaf to canopy by integrating to canopy using the relationship between single internal conductance and photosynthetic photon flux density. Using the data observed by eddy covariance method from the Changbai Mountains site of ChinaFLUX, the application of the model at the canopy scale was examined. Under no water stress, the simulated net ecosystem photosynthesis rate fitted with the observed data very well, the slope and R2 of the line regression equation of the observed and simulated values were 0.7977 and 0.8892, respectively (n = 752), and average absolute error was 3.78 μmol CO2 m-2s-1; the slope, R2 and average absolute error of transpiration rate were 0.7314, 0.4355 and 1.60mmol H2O m-2 s-1, respectively (n = 752). The relationship between canopy photosynthesis,transpiration and external environmental conditions was discussed by treating the canopy as a whole and neglecting the comprehensive feedback mechanism within canopy, and it was noted that the precipitation course affected the transpiration rate simulation badly. Compared to the models based on eco-physiological processes, the SMPT-SB model was simple and easy to be used. And it can be used as a basic carbon and water coupling model of soil-plant-atmosphere continuum.

  20. Influence of High Temperature on Photosynthesis and Transpiration Rate of Rice Seedlings at Jointing Stage%高温胁迫对拔节期水稻光合作用和蒸腾速率的影响

    Institute of Scientific and Technical Information of China (English)

    赵玉国; 王新忠; 吴沿友; 曹元军

    2012-01-01

    为进一步了解高温对水稻生长的影响机制,为水稻的田间管理提供理论依据,以拔节期镇稻6号为试验材料,对其进行1d、3d和5d的昼间(10:00-15:00)高温(35~40℃)处理,之后转入28℃条件下恢复2d,以28℃未处理水稻为对照,研究较长时间高温处理及常温恢复对水稻光合作用及蒸腾速率的影响.结果表明:昼间高温处理,水稻叶片净光合速率(Pn)和胞间CO2浓度日变化呈先下降后上升的趋势,在中午13:00达到最低点,并且随处理时间的延长逐渐降低;气孔导度(Gs)和蒸腾速率(Tr)日变化呈先上升后下降趋势,在中午13:00达到最高点,并随处理时间的延长逐渐升高;短时高温处理(5 d)后常温恢复2d,上述指标即可恢复.结论:夏季高温对拔节期水稻光合作用造成影响,且主要是由非气孔限制因素引起的;蒸腾作用增强是降低叶温的生理机制.%The rice seedlings of Zhendao 6 at jointing stage were first treated under 35-40℃ from 10:00to 15:00 for 1 d, 3 d and 5 d respectively and then the treated rice seedlings were recovered at 28 C for 2 d to study influence of high temperature stress and normal temperature recovery on photosynthesis and transpiration rate of rice seedlings, to further understand the influence mechanism of high temperature to rice seedling growth and to provide the theoretical basis for rice field management. The results showed that the diurnal variation of net photosynthetic rate and intercellular CO2 of treated rice seedlings under high temperature presented the first descent and then rising trend, reached the lowest point at 13:00 and gradually reduced with prolongation of treatment time. The diurnal variation of stomatal conductance and transpiration rate of treated rice seedlings under high temperature was the first rising and then descent trend, reached the maximum point at 13:00 and gradually increased with prolongation of treatment time. Conclusions; the

  1. A phytotoxicity test using transpiration of willows

    DEFF Research Database (Denmark)

    Trapp, Stefan; Zambrano, Kim Cecilia; Kusk, Kresten Ole

    2000-01-01

    A short-term acute toxicity assay for willow trees growing in contaminated solution or in polluted soil was developed and tested. The test apparatus consists of an Erlenmeyer flask with a prerooted tree cutting growing in it. Growth and reduction of transpiration are used to determine toxicity.......8 and 9.6 mg/L were found. This is similar to the results from algal growth rate tests. The willow tree toxicity test may be useful for determining the site-specific toxicity of polluted soils and for terrestrial risk assessment of new chemicals and pesticides....

  2. Studies on the Characteristics of Photosynthesis and Transpiration of Six Tropical Garden Plants in the Greenhouse Environment%6种热带园林植物在温室环境下的光合及蒸腾特性的研究

    Institute of Scientific and Technical Information of China (English)

    幸宏伟; 代雪

    2012-01-01

    为研究热带园林植物在温室环境下的光合及蒸腾作用,对重庆南山植物园热带温室环境条件下,苏铁蕨、象腿芭蕉、酒瓶椰子、琴叶榕、人心果和海南龙血树6种植物的光合效率、蒸腾效率及水分利用效率进行了测定,结果表明:(1)几种热带园林植物都有明显的光合速率日变化,部分树种存在因气孔导度下降而引起的"午休"现象.(2)植物的光合速率大小与植物叶绿素含量无直接相关.(3)6树种光合速率从大到小依次为:人心果,龙血树,象腿芭蕉,酒瓶椰子,苏铁蕨,琴叶榕;蒸腾速率从大到小依次为:龙血树,琴叶榕,象腿芭蕉,苏铁蕨,人心果,酒瓶椰子;水分利用效率从高到低依次为:人心果,象腿芭蕉,龙血树,琴叶榕,酒瓶椰子,苏铁蕨.%To study the photosynthesis and transpiration of tropical garden plants living in the greenhouse which is different from their original habitats, we analyzed the characteristics of photosynthesis and transpiration of cycads fern (Brainea insignis), leg-shaped banana (Ensete glaucum (Roxb.) Cheesman), bottle palm (Mascarena lagenicaulis ) , fiddle-leaved fig (Ficus pandurata ) , Jackfruit (Achras sapota ) and Hainan dragon blood tree (Dracaena carnbodianajui Pierre ex Gagnep) growing under the environ- mental conditions in Chongqing Nanshan Botanical Garden's greenhouses. An obvious diurnal variation was observed in the photosynthetic rate of all the species studied, and a phenomenon of "nap" occurred in some species owing to the decline in their stomatal conductance. Photosynthesis rate of the plants had no direct relevance to their chlorophyll content. Their photosynthetic rate appeared in the order of Jackfruit Hainan dragon blood tree 〉 leg-shaped banana 〉 bottle palm 〉 cycads fern 〉 fiddle-leaved fig, their transpiration rate was in the order of Hainan dragon blood tree〉 fiddle-leaved fig 〉 leg

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

    Science.gov (United States)

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

    2014-09-01

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

  4. The positive effect of skin transpiration in peach fruit growth.

    Science.gov (United States)

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

    2010-09-01

    The effect of fruit transpiration on the mechanisms driving peach (Prunus persica (L.) Batsch) daily growth was investigated. In peach, fruit water losses increase during the season and might play a key role in determining fruit growth. Skin transpiration was reduced during the cell expansion stage by enclosing fruit in plastic bags fitted with holes. In the first year, diameter changes of bagged and control fruit were precisely monitored for 15 days, and percentage dry matter and soluble solids content were determined during the experiment and at harvest. In the second year, midday fruit water potential, daily patterns of fruit growth and of vascular and transpiration flows were monitored. Bagging reduced fruit daily growth on some days, and negatively affected both fruit dry matter percentage and soluble solids content. Fruit transpiration rate was reduced during the midday hours, thus increasing midday fruit water potential and lowering xylem inflows. In accordance with the Münch hypothesis on traslocation, these conditions likely decreased the necessary gradient needed for the transport of phloem sap to sink organs, as in the afternoon, bagged fruit showed lower phloem inflows. These data suggest that skin transpiration in peach has a positive effect on fruit growth, as it enhances fruit phloem import.

  5. Comparing three models to estimate transpiration of desert shrubs

    Science.gov (United States)

    Xu, Shiqin; Yu, Zhongbo; Ji, Xibin; Sudicky, Edward A.

    2017-07-01

    The role of environmental variables in controlling transpiration (Ec) is an important, but not well-understood, aspect of transpiration modeling in arid desert regions. Taking three dominant desert shrubs, Haloxylon ammodendron, Nitraria tangutorum, and Calligonum mongolicum, as examples, we aim to evaluate the applicability of three transpiration models, i.e. the modified Jarvis-Stewart model (MJS), the simplified process-based model (BTA), and the artificial neural network model (ANN) at different temporal scales. The stem sap flow of each species was monitored using the stem heat balance approach over both the 2014 and 2015 main growing seasons. Concurrent environmental variables were also measured with an automatic weather station. The ANN model generally produced better simulations of Ec than the MJS and BTA models at both hourly and daily scales, indicating its advantage in solving complicated, nonlinear problems between transpiration rate and environmental driving forces. The solar radiation and vapor pressure deficit were crucial variables in modeling Ec for all three species. The performance of the MJS and ANN models was significantly improved by incorporating root-zone soil moisture. We also found that the difference between hourly and daily fitted parameter values was considerable for the MJS and BTA models. Therefore, these models need to be recalibrated when applied at different temporal scales. This study provides insights regarding the application and performance of current transpiration models in arid desert regions, and thus provides a deeper understanding of eco-hydrological processes and sustainable ecosystem management at the study site.

  6. 三种草坪草净光合速率和蒸腾速率的日变化特点研究%A study on the diurnal variation characteristics of net photosynthesis rate and transpiration rate of three species of turfgrasses

    Institute of Scientific and Technical Information of China (English)

    丁小球; 胡玉佳; 王榕楷

    2001-01-01

    The diurnal variation characteristics of net photosynthesis rate and transpiration rate of Eremochloa ophiuroides, Zoysia tenuifolia and Axonopus compressus in the sunny day were studied. The results showed that the net photosynthesis rate diurnal variation curves of Eremochloa ophiuroides and Zoysia tenuifolia were double-peaked, while the curve of Axono-pus compressus was three-peaked. The peak values of three species of turfgrasses appeared in different times, with an obvious "sleep-at-noon" phenomenon. The size order of the average value of net photosynthesis rate diurnal variation was E. ophiuroides>A. compressus>E. ophiuroides. The transpiration rate diurnal variation curves of E. ophiuroides and Z. tenuifoli a were double-peaked, while the curve of A. compressus was single-peaked, and their peak value appeared in different times either. Neither of them had an obvious"sleep-at-noon" phe-nomenon. The size order of the average value of transpiration rate was Z. tenuifolia>A. Com-pressus>E. ophiuroides. The correlations between different ecological factors and the net photosynthesis rate transpiration rate of 3 species had large difference with each other, and so it did between the same ecological factor and the net photosynthesis rate or transpiration rate of different species.%研究了在晴天的条件下,假俭草、细叶结缕草和地毯草净光合速率和蒸腾速率的日变化特点。结果表明:(1)假俭草和细叶结缕草的净光合速率的日变化曲线均为双峰型,而地毯草为三峰型,3种草出现峰值的时间不同,均有明显的"午睡"现象,日平均净光合速率的大小顺序为假俭草>地毯草>细叶结缕草;(2)假俭草和细叶结缕草的蒸腾速率的日变化曲线均为双峰型,而地毯草为单峰型,3种草出现峰值的时间有所差别,"午睡"现象均不明显,日平均蒸腾速率的大小顺序为细叶结缕草>地毯草>假俭草;(3)不同生态因子与3种草坪草净光合速率、蒸腾速

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

    Science.gov (United States)

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

    1997-01-01

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

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

    Science.gov (United States)

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

    2012-12-01

    /day, while LAI varied over a narrower range, from 2.0 - 2.9. Differences in leaf-level transpiration were due to differences in stomatal conductance among sites. Sites close to the river had higher transpiration rates than sites further away, and sites with more saline water had lower leaf-level transpiration rates. Leaf-level transpiration rates were higher in June and July, when aquifers were closer to the surface, than in August and September, when water levels had dropped. High transpiration rates were associated with finer textured soil compared to plants growing in sandy soils. Low transpiration rates were manifested by moderate to severe midday depression of stomatal conductance and transpiration. These limitations constrained the rate of saltcedar ET to about 40% of ETo, and also reduced the accuracy of remote sensing estimates of ET, which assume a constant rate of stomatal conductance during midday.

  9. Photosynthetic Rate of Soybean at Various Planting Dates

    Science.gov (United States)

    Soybean [Glycine max (L.) Merr.] yield is typically maximized by early planting in the upper Midwest USA. Seasonal carbon dioxide exchange rate (CER) has not been quantified to explain the positive yield response to early planting. Five planting dates were established between 18-April and 22-May nea...

  10. Effect of Pot Size on Various Characteristics Related to Photosynthetic Matter Production in Soybean Plants

    OpenAIRE

    Minobu Kasai; Keisuke Koide; Yuya Ichikawa

    2012-01-01

    Despite the wide uses of potted plants, information on how pot size affects plant photosynthetic matter production is still considerably limited. This study investigated with soybean plants how transplantation into larger pots affects various characteristics related to photosynthetic matter production. The transplantation was analyzed to increase leaf photosynthetic rate, transpiration rate, and stomatal conductance without affecting significantly leaf intercellular CO2 concentration, implica...

  11. Will intra-specific differences in transpiration efficiency in wheat be maintained in a high CO{sub 2} world? A FACE study

    Energy Technology Data Exchange (ETDEWEB)

    Tausz-Posch, S.; Norton, R.M.; Seneweera, S. [Univ. of Melbourne. Dept. of Agriculture and Food Systems, Creswick (Australia); Fitzgerald, G.J. [Victorian Dept. of Primary Industries, Horsham (Australia); Tausz, M. [Univ. of Melbourne. Dept. of Forest and Ecosystem Science, Creswick (Australia)

    2013-06-01

    This study evaluates whether the target breeding trait of superior leaf level transpiration efficiency is still appropriate under increasing carbon dioxide levels of a future climate using a semi-arid cropping system as a model. Specifically, we investigated whether physiological traits governing leaf level transpiration efficiency, such as net assimilation rates (A{sub net}), stomatal conductance (g{sub s}) or stomatal sensitivity were affected differently between two Triticum aestivum L. cultivars differing in transpiration efficiency (cv. Drysdale, superior; cv. Hartog, low). Plants were grown under Free Air Carbon dioxide Enrichment (FACE, approximately 550{mu}mol mol{sup -1} or ambient CO{sub 2} concentrations (approximately 390{mu}mol mol{sup -1}). Mean A{sub net} (approximately 15% increase) and g{sub s} (approximately 25% decrease) were less affected by elevated [CO{sub 2}] than previously found in FACE-grown wheat (approximately 25% increase and approximately 32% decrease, respectively), potentially reflecting growth in a dry-land cropping system. In contrast to previous FACE studies, analyses of the Ball et al. model revealed an elevated [CO{sub 2}] effect on the slope of the linear regression by 12% indicating a decrease in stomatal sensitivity to the combination of [CO{sub 2}], photosynthesis rate and humidity. Differences between cultivars indicated greater transpiration efficiency for Drysdale with growth under elevated [CO{sub 2}] potentially increasing the response of this trait. This knowledge adds valuable information for crop germplasm improvement for future climates. (Author)

  12. Evaporative demand, transpiration, and photosynthesis: How are they changing?

    Science.gov (United States)

    Farquhar, G. D.; Roderick, M. L.

    2009-04-01

    Carbon dioxide concentration is increasing. This affects photosynthesis via increases in substrate availability (Farquhar et al. 1980). It reduces the amount of water transpired by plants to fix a given amount of carbon into an organic form; i.e it increases transpiration efficiency (Wong et al. 1979). It also warms the earth's surface. It is commonly supposed that this warming causes an increase in evaporative demand - the rate of water loss from a wet surface. This supposition has then been extended to effects on plant water availability, with the idea that there would be offsets to the gains in productivity associated with increased transpiration efficiency. The assumption that increased temperature means increased evaporative demand has also been applied to global maps of changes in soil water content. However, observations of pan evaporation rate show that this measure of evaporative demand has been decreasing in most areas examined over the last few decades. We reconcile these observations with theory by noting that, on long time scales, warming also involves water bodies, so that the vapour pressure at the earth's surface also increases. Using the physics of pan evaporation (Rotstayn et al. 2006) we show that the reduction in evaporative demand has been associated with two main effects, (1) "dimming", a reduction in sunlight received at the earth's surface because of aerosols and clouds, being the first phenomenon identified (Roderick and Farquhar 2002), and (2) "stilling", a reduction in wind speed, being the second (Roderick et al. 2007). We show that better accounting for changes in evaporative demand is important for estimating soil water changes, particularly in regions where precipitation exceeds evaporative demand (i.e where there are rivers) (Hobbins et al. 2008). We synthesise some of these results with others on vegetation change. References: Farquhar, GD, von Caemmerer, S, and Berry, JA, 1980: A biochemical model of photosynthetic CO2 assimilation

  13. On the unsteady Reynolds thermal transpiration law

    Science.gov (United States)

    Ziółkowski, P.; Badur, J.

    2016-10-01

    This paper presents the phenomenon of unsteady Reynolds thermal transpiration flow. The possible constitutive equations in the transpiration shell-like layer were studied analytically and numerically. There has been also examined experimental case of helium flow from cold to hot reservoir in nanopipe.

  14. Auxin metabolism rates and implications for plant development

    Directory of Open Access Journals (Sweden)

    Eric M Kramer

    2015-03-01

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

  15. 玛纳斯河流域荒漠植被单株茎干液流及光合蒸腾特性研究%Study of Liquid Flow and the Characteristics of Photosynthesis and Transpiration of Vegetation Plant Stems in Manasi River Basin

    Institute of Scientific and Technical Information of China (English)

    陈思; 何新林; 杨广; 许双堆; 杨文新

    2014-01-01

    植物茎干液流量可表征其蒸腾耗水量,反映植被水分传输状况,可用于计算植被生态需水量。以玛纳斯河流域古尔班通古特沙漠南缘典型荒漠植被梭梭、柽柳为研究对象,通过数据监测,研究植被茎干液流及光合蒸腾特性,分析气象因子及土壤含水率对茎干液流的影响。结果表明:梭梭、柽柳茎干液流速率呈明显的昼夜变化规律,白天液流速率远高于夜间;梭梭的净光合速率日变化模式为双峰型,柽柳为单峰型;梭梭蒸腾速率的日变化有明显上升和下降过程,柽柳趋势不明显,呈小幅震荡;液流速率变化与相对空气湿度呈负相关,空气湿度高时液流速率低;气温、总辐射与液流速率的变化趋势基本一致,液流速率随着气温或总辐射的增强而增大;随着土壤含水率降低,液流速率降低。%Plant stem sap flow of water consumption ,that reflects the status of vegetation water transmission ,and determines the vegetation ecological water requirement .Research's study objectn is Haloxylon ammodendron and Tamarix vegetation that in the southern Gurbantunggut Desert of Manasi River Basin ,Through the data monitoring to research the liquid flow and the characteris-tics of photosynthesis and transpiration of vegetation stem ,and analysis of the effect on the stem sap flow of meteorological factors and soil moisture content .The results show that :Haloxylon ammodendron and Tamarix stem sap flow rate showed a significant di-urnal variation ,the flow rate is much higher than the night .Changes in net photosynthetic rate of Haloxylon ammodendron mode light of day is shuangfeng type and Tamarix chinensis belong to Single peak type .Diurnal changes of transpiration rate of Haloxylon ammodendron had the obvious rise and fall ,but Tamarix tendency is not obviously .The liquid flow rate was negatively correlated with relative humidity of the air ,and the change trend

  16. Transpiration of shrub species, Alnus firma under changing atmospheric environments in montane area, Japan

    Science.gov (United States)

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

    2014-12-01

    In the large caldera of Mt. Aso in Japan, grasslands have been traditionally managed by the farmers. Due to changes in the social structure of the region, a large area of the grassland has been abandoned and was invaded by the shrubs with different hydrological and ecophysiological traits. Ecophysiological traits and their responses to seasonally changing environments are fundamental to project the transpiration rates under changing air and soil water environments, but less is understood. We measured the tree- and leaf-level ecophysiological traits of a shrub, Alnus firma in montane region where both rainfall and soil water content drastically changes seasonally. Sap flux reached the annual peak in evaporative summer (July-August) both in 2013 and 2014, although the duration was limited within a short period due to the prolonged rainy season before summer (2014) and rapid decrease in the air vapor pressure deficit (D) in late summer. Leaf ecophysiological traits in close relationship with gas exchange showed modest seasonal changes and the values were kept at relatively high levels typical in plants with nitrogen fixation under nutrient-poor environments. Stomatal conductance, which was measured at leaf-level measurements and sap flux measurements, showed responses to D, which coincided with the theoretical response for isohydric leaves. A multilayer model, which estimates stand-level transpiration by scaling up the leaf-level data, successfully captured the temporal trends in sap flux, suggesting that major processes were incorporated. Thus, ecophysiological traits of A. firma were characterized by the absence of responses to seasonally changing environments and the transpiration rate was the function of the interannually variable environmental conditions.

  17. Transpiration in an oil palm landscape: effects of palm age

    Science.gov (United States)

    Röll, A.; Niu, F.; Meijide, A.; Hardanto, A.; Hendrayanto; Knohl, A.; Hölscher, D.

    2015-10-01

    Oil palm (Elaeis guineensis Jacq.) plantations cover large and continuously increasing areas of humid tropical lowlands. Landscapes dominated by oil palms usually consist of a mosaic of mono-cultural, homogeneous stands of varying age, which may be heterogeneous in their water use characteristics. However, studies on the water use characteristics of oil palms are still at an early stage and there is a lack of knowledge on how oil palm expansion will affect the major components of the hydrological cycle. To provide first insights into hydrological landscape-level consequences of oil palm cultivation, we derived transpiration rates of oil palms in stands of varying age, estimated the contribution of palm transpiration to evapotranspiration, and analyzed the influence of fluctuations in environmental variables on oil palm water use. We studied 15 two- to 25-year old stands in the lowlands of Jambi, Indonesia. A sap flux technique with an oil palm specific calibration and sampling scheme was used to derive leaf-, palm- and stand-level water use rates in all stands under comparable environmental conditions. Additionally, in a two- and a 12-year old stand, eddy covariance measurements were conducted to derive evapotranspiration rates. Water use rates per leaf and palm increased 5-fold from an age of 2 years to a stand age of approx. 10 years and then remained relatively constant. A similar trend was visible, but less pronounced, for estimated stand transpiration rates of oil palms; they varied 12-fold, from 0.2 mm day-1 in a 2-year old to 2.5 mm day-1 in a 12-year old stand, showing particularly high variability in transpiration rates among medium-aged stands. Comparing sap flux and eddy-covariance derived water fluxes suggests that transpiration contributed 8 % to evapotranspiration in the 2-year old stand and 53 % in the 12-year old stand, indicating variable and substantial additional sources of evaporation, e.g., from the soil, the ground vegetation and from trunk

  18. Habitat Temperature and Precipitation of Arabidopsis thaliana Ecotypes Determine the Response of Foliar Vasculature, Photosynthesis, and Transpiration to Growth Temperature.

    Science.gov (United States)

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

    2016-01-01

    Acclimatory adjustments of foliar vascular architecture, photosynthetic capacity, and transpiration rate in Arabidopsis thaliana ecotypes (Italian, Polish [Col-0], Swedish) were characterized in the context of habitat of origin. Temperatures of the habitat of origin decreased linearly with increasing habitat latitude, but habitat precipitation was greatest in Italy, lowest in Poland, and intermediate in Sweden. Plants of the three ecotypes raised under three different growth temperature regimes (low, moderate, and high) exhibited highest photosynthetic capacities, greatest leaf thickness, highest chlorophyll a/b ratio and levels of β-carotene, and greatest levels of wall ingrowths in phloem transfer cells, and, in the Col-0 and Swedish ecotypes, of phloem per minor vein in plants grown at the low temperature. In contrast, vein density and minor vein tracheary to sieve element ratio increased with increasing growth temperature - most strongly in Col-0 and least strongly in the Italian ecotype - and transpirational water loss correlated with vein density and number of tracheary elements per minor vein. Plotting of these vascular features as functions of climatic conditions in the habitat of origin suggested that temperatures during the evolutionary history of the ecotypes determined acclimatory responses of the foliar phloem and photosynthesis to temperature in this winter annual that upregulates photosynthesis in response to lower temperature, whereas the precipitation experienced during the evolutionary history of the ecotypes determined adjustment of foliar vein density, xylem, and transpiration to temperature. In particular, whereas photosynthetic capacity, leaf thickness, and foliar minor vein phloem features increased linearly with increasing latitude and decreasing temperature of the habitats of origin in response to experimental growth at low temperature, transpiration rate, foliar vein density, and minor vein tracheary element numbers and cross

  19. Habitat temperature and precipitation of Arabidopsis thaliana ecotypes determine the response of foliar vasculature, photosynthesis, and transpiration to growth temperature

    Directory of Open Access Journals (Sweden)

    William Walter Adams III

    2016-07-01

    Full Text Available Acclimatory adjustments of foliar vascular architecture, photosynthetic capacity, and transpiration rate in Arabidopsis thaliana ecotypes (Italian, Polish [Col-0], Swedish were characterized in the context of habitat of origin. Temperatures of the habitat of origin decreased linearly with increasing habitat latitude, but habitat precipitation was greatest in Italy, lowest in Poland, and intermediate in Sweden. Plants of the three ecotypes raised under three different growth temperature regimes (low, moderate, and high exhibited highest photosynthetic capacities, greatest leaf thickness, highest chlorophyll a/b ratio and levels of β-carotene, and greatest levels of wall ingrowths in phloem transfer cells, and, in the Col-0 and Swedish ecotypes, of phloem per minor vein in plants grown at the low temperature. In contrast, vein density and minor vein tracheary to sieve element ratio increased with increasing growth temperature – most strongly in Col-0 and least strongly in the Italian ecotype – and transpirational water loss correlated with vein density and number of tracheary elements per minor vein. Plotting of these vascular features as functions of climatic conditions in the habitat of origin suggested that temperatures during the evolutionary history of the ecotypes determined acclimatory responses of the foliar phloem and photosynthesis to temperature in this winter annual that upregulates photosynthesis in response to lower temperature, whereas the precipitation experienced during the evolutionary history of the ecotypes determined adjustment of foliar vein density, xylem, and transpiration to temperature. In particular, whereas photosynthetic capacity, leaf thickness, and foliar minor vein phloem features increased linearly with increasing latitude and decreasing temperature of the habitats of origin in response to experimental growth at low temperature, transpiration rate, foliar vein density, and minor vein tracheary element numbers

  20. Transpiration in an oil palm landscape: effects of palm age

    Directory of Open Access Journals (Sweden)

    A. Röll

    2015-06-01

    Full Text Available Oil palm (Elaeis guineensis Jacq. plantations cover large and continuously increasing areas of humid tropical lowlands. Landscapes dominated by oil palms usually consist of a mosaic of mono-cultural, homogeneous stands of varying age, which may be heterogeneous in their water use characteristics. However, studies on the water use characteristics of oil palms are still at an early stage and there is a lack of knowledge on how oil palm expansion will affect the major components of the hydrological cycle. To provide first insights into hydrological landscape-level consequences of oil palm cultivation, we derived transpiration rates of oil palms in stands of varying age, estimated the contribution of palm transpiration to evapotranspiration, and analyzed the influence of fluctuations in environmental variables on oil palm water use. We studied 15 two- to 25 year old stands in the lowlands of Jambi, Indonesia. A sap flux technique with an oil palm specific calibration and sampling scheme was used to derive leaf-, palm- and stand-level water use rates in all stands under comparable environmental conditions. Additionally, in a two- and a 12 year old stand, eddy covariance measurements were conducted to derive evapotranspiration rates. Water use rates per leaf and palm increased 5-fold from an age of two years to a stand age of approx. 10 years and then remained relatively constant. A similar trend was visible, but less pronounced, for estimated stand transpiration rates of oil palms; they varied 12-fold, from 0.2 mm day−1 in a 2 year old to 2.5 mm day−1 in a 12 year old stand, showing particularly high variability in transpiration rates among medium-aged stands. Confronting sap flux and eddy-covariance derived water fluxes suggests that transpiration contributed 8 % to evapotranspiration in the 2 year old stand and 53 % in the 12 year old stand, indicating variable and substantial additional sources of evaporation, e.g. from the soil, the ground

  1. Mathematical Modeling of Dual Intake Transparent Transpired Solar Collector

    Directory of Open Access Journals (Sweden)

    Thomas Semenou

    2015-01-01

    Full Text Available Nowadays, in several types of commercial or institutional buildings, a significant rise of transpired solar collectors used to preheat the fresh air of the building can be observed. Nevertheless, when the air mass flow rate is low, the collector efficiency collapses and a large amount of energy remains unused. This paper presents a simple yet effective mathematical model of a transparent transpired solar collector (TTC with dual intake in order to remove stagnation problems in the plenum and ensure a better thermal efficiency and more heat recovery. A thermal model and a pressure loss model were developed. Then, the combined model was validated with experimental data from the Solar Rating and Certification Corporation (SRCC. The results show that the collector efficiency can be up to 70% and even 80% regardless of operating conditions. The temperature gain is able to reach 20°K when the solar irradiation is high.

  2. Moisture detection through thermographic measurements of transpiration

    Science.gov (United States)

    Ludwig, Nicola; Rosina, Elisabetta

    1997-04-01

    Damage due to moisture and particularly to evaporation is one of the major causes of decay of wall surfaces in ancient buildings. The evaporative rate of water in building materials can be related to the alteration (chips, gallets) caused by salts crystallization when the water evaporates through the surface of the wall. Current and future usage of NDT heavily depends on the possibility to precisely measure physical variables which present large sensitivity to small variations of water content. A NDT thermography allows us to exactly determine the evaporation rate because of both the high value of water latent heat and the high sensibility of thermographic devices. The research has been carried out both in the laboratory and on the field measuring relative humidity and temperature in a frescoed wall of the castle of Malpaga (Northern Italy). In laboratory a climatic room has been set up using a thermovision system and a temperature & RH% probes, to analyze the evaporative phenomena. A mathematical model, although approximate, is proposed to describe the energy balance of the surface where evaporation is present. The model has been applied to the fresco to correlate the temperature to the evaporation rate. This method allows us to correlate the decay, due to the capillary raise of water in the masonry, to the transpiration phenomena.

  3. Modeling the crop transpiration using an optimality-based approach

    Institute of Scientific and Technical Information of China (English)

    Stanislaus; J.Schymanski; Murugesu; Sivapalan

    2008-01-01

    Evapotranspiration constitutes more than 80% of the long-term water balance in Northern China.In this area,crop transpiration due to large areas of agriculture and irrigation is responsible for the majority of evapotranspiration.A model for crop transpiration is therefore essential for estimating the agricultural water consumption and understanding its feedback to the environment.However,most existing hydrological models usually calculate transpiration by relying on parameter calibration against local observations,and do not take into account crop feedback to the ambient environment.This study presents an optimality-based ecohydrology model that couples an ecological hypothesis,the photosynthetic process,stomatal movement,water balance,root water uptake and crop senescence,with the aim of predicting crop characteristics,CO2 assimilation and water balance based only on given meteorological data.Field experiments were conducted in the Weishan Irrigation District of Northern China to evaluate performance of the model.Agreement between simulation and measurement was achieved for CO2 assimilation,evapotranspiration and soil moisture content.The vegetation optimality was proven valid for crops and the model was applicable for both C3 and C4 plants.Due to the simple scheme of the optimality-based approach as well as its capability for modeling dynamic interactions between crops and the water cycle without prior vegetation information,this methodology is potentially useful to couple with the distributed hydrological model for application at the watershed scale.

  4. Motionless heat pump - A new application of thermal transpiration

    Science.gov (United States)

    Kugimoto, K.; Hirota, Y.; Kizaki, Y.

    2016-11-01

    A motionless heat pump system using a combination of thermal transpiration flow of a rarefied gas and a phase change of water has been proposed. This system consists primarily of a thermal transpiration pump, referred to as a Knudsen pump, and two chambers filled with water and water vapor, respectively. The Knudsen pump moves water vapor from one chamber to the other. The pressure drop in the outflow chamber promotes the evaporation of water and heat absorption, whereas the pressure increase in the inflow chamber promotes vapor condensation and heat generation. The maximum pressure difference and mass flow rate obtained by a Knudsen pump composed of a glass fiber filter were 57.6 Pa and 0.0484 mg/s/cm2, respectively, at a temperature difference across the filter of 120 K between the two chambers. The vapor delivery capacity of this pump was also measured experimentally.

  5. 用茎流计研究冬小麦蒸腾规律%Experimental Research on Transpiration of Winter Wheat with Stem Flow Gauge

    Institute of Scientific and Technical Information of China (English)

    谢华; 沈荣开

    2001-01-01

    Stem-flow gauge can measure plant flow rate directly. In this paper, we have evaluated the value of the instrument through farmland experiment and theory calculation. The result shows that the change of wheat transpiration has strong correlation with solar radiation in daytime, and the solar radiation is the most important factor in deciding the wheat transpirtion in the day. On the other hand.in nighttime, the transpiration mainly depend on temperature,windspeed, and saturation vapor pressure.etc. In usual night, there is no transpiration, but if the windspeed and temperature is high enough. winter wheat will have a little transpiration,and the transpiration changes in a certain regular pattern in clear night.%通过田间试验及理论计算,验证了对茎流计在测量作物蒸腾方面的实用价值。试验观测表明,白天的作物蒸腾变化与太阳辐射值有很强的相关关系,太阳辐射是白天作物蒸腾的主要影响因素;作物夜晚的蒸腾变化主要受气温、风速、空气饱和差等因素的影响。通常,作物夜晚没有蒸腾,但在气温较高,风速较大的夜晚.作物就会产生很小的蒸腾,在天气晴朗的夜晚,作物夜晚蒸腾速率的变化遵循着一定的规律。

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

    Science.gov (United States)

    Chanzy, A.; Nourtier, M.

    2011-12-01

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

  7. Wind increases "evaporative demand" but reduces plant water requirements

    Science.gov (United States)

    Schymanski, S. J.; Or, D.

    2015-12-01

    Transpiration is commonly conceptualised as a fraction of some potential rate, determined by stomatal or canopy resistance. Therefore, so-called "atmospheric evaporative demand" or "potential evaporation" is generally used alongside with precipitation and soil moisture to characterise the environmental conditions that affect plant water use. An increase in potential evaporation (e.g. due to climate change) is generally believed to cause increased transpiration and/or vegetation water stress, aggravating drought effects. In the present study, we investigated the question whether potential evaporation constitutes a meaningful reference for transpiration and compared sensitivity of potential evaporation and leaf transpiration to atmospheric forcing. Based on modelling results and supporting experimental evidence, we conclude that stomatal resistance cannot be parameterised as a factor relating transpiration to potential evaporation, as the ratio between transpiration and potential evaporation not only varies with stomatal resistance, but also with wind speed, air temperature, irradiance and relative humidity. Furthermore, the effect of wind speed in particular implies increase in potential evaporation, which is commonly interpreted as increased "water stress", but at the same time can reduce leaf transpiration, implying a decrease in water demand at the leaf scale. In fact, in a range of field measurements, we found that water use efficiency (WUE, carbon uptake per water transpired) commonly increases with increasing wind speed, enabling plants to conserve water during photosynthesis. We estimate that the observed global decrease in terrestrial near-surface wind speeds could have reduced WUE at a magnitude similar to the increase in WUE attributed to global rise in atmospheric carbon dioxide concentrations. We conclude that trends in wind speed and atmospheric carbon dioxide concentrations have to be considered explicitly for the estimation of drought effects on

  8. Risk rating in the tea planting industry: The employees′ opinion

    Directory of Open Access Journals (Sweden)

    Joseph Bobby

    2010-01-01

    Full Text Available Background: Workers in the tea planting industry are exposed to a variety of occupational health and safety hazards. Whether the workers perceive the risks involved and to what degree is an interesting point in question. Aims: To identify occupational health and safety risks involved in the tea planting sector and to rate these risks from the workers′ perspective. Settings and Design: Permanent workers from four estates belonging to one tea planting company in southern India were enlisted in this descriptive study . Materials and Methods: The sample was randomly and then proportionately selected to give a total number equal to the calculated sample size of 341. Data were collected by reviewing medical records, conducting focus group discussions with field officers and supervisors, worker interviews and key informant interviews with the management in these four estates. Proportions were used to describe occurrence and distribution of work-related injuries. The risks as perceived by the workers were rated on their severity and frequency, using a Risk Rating Matrix. Results and Conclusion: The incidence of injuries was greater among male workers, those working both in the field and factory and those handling multiple tasks. The most common morbidities suffered were "small cuts and abrasions" in about 53%of the workers. Backache and insect bites were assigned the highest risk rating scores. Continued monitoring of the risk assessment by the workers could help in a planned reduction of commonly occurring injuries by agreeing on a specified risk limit.

  9. The transient transpiration heat flux meter

    Energy Technology Data Exchange (ETDEWEB)

    Martins, N. [Dept. de Engenharia Mecanica-DEM, Universidade de Aveiro, Campus Universitario de Santiago, 3810-193 Aveiro (Portugal)]. E-mail: nmartins@mec.ua.pt; Calisto, H. [Dept. de Engenharia Mecanica-DEM, Universidade de Aveiro, Campus Universitario de Santiago, 3810-193 Aveiro (Portugal); Afgan, N. [Instituto Superior Tecnico, Av. Rovisco Pais, 1049-001 Lisbon (Portugal); Leontiev, A.I. [Moscow State Technical University, 2nd Baumanskaya Str. 5, Moscow 107005 (Russian Federation)

    2006-10-15

    A new heat flux measurement principle, based on the transient response of a transpiration radiometer, is proposed. The measurement principle of current transpiration radiometers is based on a steady-state temperature measurement in a porous element. Since it may typically take several seconds to reach these conditions, there are obvious benefits in reducing the instrument response time. This can be achieved through the analysis of its transient response in order to predict the incident heat flux. In addition, the proposed methodology enables the separate measurement of the radiative and convective components of incident heat fluxes, without compromising the known advantages of transpiration radiometers. The availability of such an instrument may enable the development of advanced monitoring, diagnostic and control systems for thermal equipment.

  10. Variable coupling between sap-flow and transpiration in pine trees under drought conditions

    Science.gov (United States)

    Preisler, Yakir; Tatarinov, Fyodor; Rohatyn, Shani; Rotenberg, Eyal; Grunzweig, Jose M.; Yakir, Dan

    2016-04-01

    Changes in diurnal patterns in water transport and physiological activities in response to changes in environmental conditions are important adjustments of trees to drought. The rate of sap flow (SF) in trees is expected to be in agreement with the rate of tree-scale transpiration (T) and provides a powerful measure of water transport in the soil-plant-atmosphere system. The aim of this five-years study was to investigate the temporal links between SF and T in Pinus halepensis exposed to extreme seasonal drought in the Yatir forest in Israel. We continuously measured SF (20 trees), the daily variations in stem diameter (ΔDBH, determined with high precision dendrometers; 8 trees), and ecosystem evapotranspiration (ET; eddy covariance), which were complemented with short-term campaigns of leaf-scale measurements of H2O and CO2 gas exchange, water potentials, and hydraulic conductivity. During the rainy season, tree SF was well synchronized with ecosystem ET, reaching maximum rates during midday in all trees. However, during the dry season, the daily SF trends greatly varied among trees, allowing a classification of trees into three classes: 1) Trees that remain with SF maximum at midday, 2) trees that advanced their SF peak to early morning, and 3) trees that delayed their SF peak to late afternoon hours. This classification remained valid for the entire study period (2010-2015), and strongly correlated with tree height and DBH, and to a lower degree with crown size and competition index. In the dry season, class 3 trees (large) tended to delay the timing of SF maximum to the afternoon, and to advance their maximum diurnal DBH to early morning, while class 2 trees (smaller) advanced their SF maximum to early morning and had maximum daily DBH during midday and afternoon. Leaf-scale transpiration (T), measurements showed a typical morning peak in all trees, irrespective of classification, and a secondary peak in the afternoon in large trees only. Water potential and

  11. Whole-plant capacitance, embolism resistance and slow transpiration rates all contribute to longer desiccation times in woody angiosperms from arid and wet habitats

    Science.gov (United States)

    Low water potentials in xylem can result in damaging levels of cavitation, yet little is understood about which hydraulic traits have most influence in delaying the onset of hydraulic dysfunction during periods of drought. We examined three traits contributing to longer desiccation times in excised ...

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

    Science.gov (United States)

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

    In order to predict carbon sequestration of vegetation with the future rise in atmospheric CO 2 concentration, [CO 2] and temperature, long term effects of high [CO 2] and high temperature on responses of both photosynthesis and transpiration of plants as a whole community to environmental parameters need to be elucidated. Especially in the last decade, many studies on photosynthetic acclimation to elevated [CO 2] at gene, cell, tissue or leaf level for only vegetative growth phase ( i.e. before formation of reproductive organs) have been conducted all over the world. However, CO 2 acclimation studies at population or community level for a whole growing season are thus far very rare. Data obtained from repeatable experiments at population or community level for a whole growing season are necessary for modeling carbon sequestration of a plant community. On the other hand, in order to stabilize material circulation in the artificial ecological system of Closed Ecology Experiment Facilities (CEEF), it is necessary to predict material exchange rates in the biological systems. In particular, the material exchange rate in higher plant systems is highly variable during growth periods and there is a strong dependence on environmental conditions. For this reason, dependencies of both CO 2 exchange rate and transpiration rate of three rice populations grown from seed under differing conditions of [CO 2] and day/night air temperature (350 μL CO 2 L -1, 24/17°C (population A); 700 μL CO 2 L -1, 24/17°C (population B) and 700 μL CO 2 L -1, 26/19°C (population C)) upon PPFD, leaf temperature and [CO 2] were investigated every two weeks during whole growing season. Growth of leaf lamina, leaf sheath, panicle and root was also compared. From this experiment, it was elucidated that acclimation of instantaneous photosynthetic response of rice population to [CO 2] occurs in vegetative phase through changes in ratio of leaf area to whole plant dry weight, LAR. But, in

  13. The stem heat balance method to measure transpiration:Evaluation of a new sensor

    Science.gov (United States)

    The direct measurement of crop transpiration (Tcrop) under field conditions and throughout the growing season is difficult to obtain. An available method uses stem flow gauge sensors, based on the stem heat balance. The sensor consists of a small heater that is wrapped around the stem of the plant a...

  14. Partitioning evaporation and transpiration in a maize field using heat pulse sensors for evaporation measurement

    Science.gov (United States)

    Evapotranspiration (ET) is the sum of soil water evaporation (E) and plant transpiration (T). E and T occur simultaneously in many systems with varying levels of importance, yet it is often very challenging to distinguish these fluxes separately in the field. Few studies have measured all three term...

  15. Archaeological data reveal slow rates of evolution during plant domestication.

    Science.gov (United States)

    Purugganan, Michael D; Fuller, Dorian Q

    2011-01-01

    Domestication is an evolutionary process of species divergence in which morphological and physiological changes result from the cultivation/tending of plant or animal species by a mutualistic partner, most prominently humans. Darwin used domestication as an analogy to evolution by natural selection although there is strong debate on whether this process of species evolution by human association is an appropriate model for evolutionary study. There is a presumption that selection under domestication is strong and most models assume rapid evolution of cultivated species. Using archaeological data for 11 species from 60 archaeological sites, we measure rates of evolution in two plant domestication traits--nonshattering and grain/seed size increase. Contrary to previous assumptions, we find the rates of phenotypic evolution during domestication are slow, and significantly lower or comparable to those observed among wild species subjected to natural selection. Our study indicates that the magnitudes of the rates of evolution during the domestication process, including the strength of selection, may be similar to those measured for wild species. This suggests that domestication may be driven by unconscious selection pressures similar to that observed for natural selection, and the study of the domestication process may indeed prove to be a valid model for the study of evolutionary change.

  16. SPATULA links daytime temperature and plant growth rate.

    Science.gov (United States)

    Sidaway-Lee, Kate; Josse, Eve-Marie; Brown, Alanna; Gan, Yinbo; Halliday, Karen J; Graham, Ian A; Penfield, Steven

    2010-08-24

    Plants exhibit a wide variety of growth rates that are known to be determined by genetic and environmental factors, and different plants grow optimally at different temperatures, indicating that this is a genetically determined character. Moderate decreases in ambient temperature inhibit vegetative growth, but the mechanism is poorly understood, although a decrease in gibberellin (GA) levels is known to be required. Here we demonstrate that the basic helix-loop-helix transcription factor SPATULA (SPT), previously known to be a regulator of low temperature-responsive germination, mediates the repression of growth by cool daytime temperatures but has little or no growth-regulating role under warmer conditions. We show that only daytime temperatures affect vegetative growth and that SPT couples morning temperature to growth rate. In seedlings, warm temperatures inhibit the accumulation of the SPT protein, and SPT autoregulates its own transcript abundance in conjunction with diurnal effects. Genetic data show that repression of growth by SPT is independent of GA signaling and phytochrome B, as previously shown for PIF4. Our data suggest that SPT integrates time of day and temperature signaling to control vegetative growth rate.

  17. Transpiration by two poplar varieties grown as coppice for biomass production.

    Science.gov (United States)

    Allen, Simon J.; Hall, Robin L.; Rosier, Paul T. W.

    1999-07-01

    Fast-growing tree clones selected for biomass plantations are highly productive and therefore likely to use more water than the agricultural crops they replace. We report field measurements of transpiration through the summer of 1994 from two poplar clones, Beaupré (Populus trichocarpa Torr. & A. Gray x P. deltoides Bartr. ex Marsh.) and Dorschkamp (P. deltoides x P. nigra L.), grown as unirrigated short-rotation coppice in southern England. Stand transpiration was quantified by scaling up from sap flow measurements made with the heat balance method in a sample of stems. Leaf conductances, leaf area development, meteorological variables and soil water deficit were also measured to investigate the response of the trees to the environment. High rates of transpiration were found for Beaupré. In June, when soil water was plentiful, the mean (+/- SD) transpiration rate over an 18-day period was 5.0 +/- 1.8 mm day(-1), reaching a maximum of 7.9 mm day(-1). Transpiration rates from Dorschkamp were lower, as a result of its lower leaf area index. High total leaf conductances were measured for both Beaupré (0.34 +/- 0.17 mol m(-2) s(-1)) and Dorschkamp (0.39 +/- 0.16 mol m(-2) s(-1)). Leaf conductance declined slightly with increasing atmospheric vapor pressure deficit in both clones, but only in Beaupré did leaf conductance decrease as soil water deficit increased.

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

    Science.gov (United States)

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

    2014-05-01

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

  19. Two-Site Comparison of Transpiration by Larrea Tridentata

    Science.gov (United States)

    Cavanaugh, M. L.; Kurc, S. A.; Scott, R. L.; Bryant, R. B.

    2008-12-01

    As a result of landscape changes within the desert southwestern U.S. such as increased grazing, reduced wildfire frequency, and changes in atmospheric conditions, the native creosotebush (Larrea tridentata) has encroached upon historically grass-dominated ecosystems, expanding in range and land cover density. To understand how creosotebush influences the water budget of ecosystems, heat balance sap flow sensors were employed on creosotebush stems at both the Santa Rita Experimental Range (SRER) and Walnut Gulch Experimental Watershed (WGEW). Additionally, both sites are equipped with eddy covariance towers, associated micrometeorological measurements, and profiles of water content reflectometers for soil moisture. The differences found between the two sites, including soil type and precipitation regime, are the basis of the following hypotheses. Firstly, we hypothesize that we will not see transpiration (T) responses following storms less than 5 mm at both sites. Secondly, we hypothesize that at both sites we will see a lagged response of T to large precipitation events, with evaporation being the dominate component in the partitioning of evapotranspiration (ET) for the first two days. Thirdly, we hypothesize that the ratio of plant transpiration to total evapotranspiration (T/ET) will be less at SRER due to the larger amount of bare soil exposed at this site. In this study, we show data from one summer at both sites and show how these relate to different precipitation events and soil moisture reservoirs.

  20. Response of mycorrhizal periwinkle plants to aster yellows phytoplasma infection.

    Science.gov (United States)

    Kamińska, Maria; Klamkowski, Krzysztof; Berniak, Hanna; Sowik, Iwona

    2010-03-01

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

  1. Effect of a chemical manufacturing plant on community cancer rates

    Directory of Open Access Journals (Sweden)

    Churches Tim

    2005-04-01

    Full Text Available Abstract 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 nearby bay and used to reclaim land along the foreshore, leaving a legacy of significant dioxin contamination. Methods We selected 20 Census Collector Districts within 1.5 kilometres of the former manufacturing plant as the study area. We obtained data on all cases of cancer and deaths from cancer in New South Wales from 1972 to 2001. We also compared rates for some cancer types that have been associated with dioxin exposure. Based on a person's residential address at time of cancer diagnosis, or at time of death due to cancer, various geo-coding software and processes were used to determine which collector district the case or death should be attributed to. Age and sex specific population data were used to calculate standardised incidence ratios and standardised mortality ratios, to compare the study area to two comparison areas, using indirect standardisation. Results During the 30-year study period 1,106 cases of cancer and 524 deaths due to cancer were identified in the study area. This corresponds to an age-sex standardised rate of 3.2 cases per 1,000 person-years exposed and 1.6 deaths per 1,000 person-years exposed. The study area had a lower rate of cancer and deaths from cancer than the comparison areas. The case incidence and mortality due to lung and bronchus carcinomas and haematopoietic cancers did not differ significantly from the comparison areas for the study period. There was no obvious geographical trend in ratios when comparing individual collector districts to New South Wales according to distance from the potential

  2. Field determintation of young acid lime plants transpiration by the stem heat balance method Determinação da transpiração de plantas jovens de lima ácida a campo pelo método de balanço de calor caulinar

    Directory of Open Access Journals (Sweden)

    Maurício Antonio Coelho Filho

    2005-06-01

    Full Text Available The stem heat balance method (HBM measures sap flow (SF in plants, and can be used to estimate daily transpiration flow. It is a powerful technique for water relations and irrigation field studies, but it has to be tested in species of particular interest. This paper discusses effectiveness of the HBM to estimate transpiration of young acid lime plants (Citrus latifolia Tan. cv. Tahiti, grafted on citrumelo cv. Swingle (Poncirus trifoliata Raf. x C. paradisi Macf., in the field using commercial gauges (model SAG10-ws, Dynamax Inc., Huston, in Piracicaba, State of Sao Paulo, Brazil. SF was correlated to transpiration determined by weighing lysimeters and by a steady-state null-balance porometer. The mean ratio between daily values of SF and lysimetric measurements was practically unitary, showing a mean difference of only 0.05%, being the comparisons of values in periods shorter than 24 hours impaired by effect of wind turbulence on lysimeters. The same occurred (mean difference of 0.38% when SF and canopy transpiration estimated from porometer measurements were compared in 20-min periods, but transpiration tended to exceed SF in periods of higher transpiration and data dispersion was high (r² = 0.48. An analysis of the sources errors of the techniques was done, including the comparison of the daily course of SF and net radiation. Despite of the dispersion of the comparative data between the HBM and the other two techniques, HBM had a good performance, permitting to recommend its use in studies of water relations in young citrus plants under field conditions.O método de balanço de calor caulinar (MBC é usado na estimativa de fluxo de seiva (SF de plantas herbáceas e lenhosas, sendo uma ferramenta útil na determinação de transpiração em estudos de relações hídricas e no manejo da irrigação. É recomendável testar o seu desempenho em espécies de interesse. Neste estudo ele foi testado em plantas jovens de lima ácida (Citrus

  3. Real-Time Determination of Photosynthesis, Transpiration, Water-Use Efficiency and Gene Expression of Two Sorghum bicolor (Moench Genotypes Subjected to Dry-Down

    Directory of Open Access Journals (Sweden)

    Alessandra Fracasso

    2017-05-01

    Full Text Available Plant growth and productivity are strongly affected by limited water availability in drought prone environments. The current climate change scenario, characterized by long periods without precipitations followed by short but intense rainfall, forces plants to implement different strategies to cope with drought stress. Understanding how plants use water during periods of limited water availability is of primary importance to identify and select the best adapted genotypes to a certain environment. Two sorghum genotypes IS22330 and IS20351, previously characterized as drought tolerant and drought sensitive genotypes, were subjected to progressive drought stress through a dry-down experiment. A whole-canopy multi-chamber system was used to determine the in vivo water use efficiency (WUE. This system records whole-canopy net photosynthetic and transpiration rate of 12 chambers five times per hour allowing the calculation of whole-canopy instantaneous WUE daily trends. Daily net photosynthesis and transpiration rates were coupled with gene expression dynamics of five drought related genes. Under drought stress, the tolerant genotype increased expression level for all the genes analyzed, whilst the opposite trend was highlighted by the drought sensitive genotype. Correlation between gene expression dynamics and gas exchange measurements allowed to identify three genes as valuable candidate to assess drought tolerance in sorghum.

  4. DNS of turbulent Couette flow with transpiration - spectra and symmetry induced scaling laws

    Science.gov (United States)

    Hoyas, Sergio; Kraheberger, Stefanie; Oberlack, Martin

    2016-11-01

    We present DNS results of turbulent plane Couette flow with constant wall-normal transpiration for Reynolds numbers of Reτ = 250 , 500 , 1000 and several transpiration Reynolds numbers Retr =V0 /Uw . To obtain the DNS data, a pseudo-spectral code, which originally was developed at UP Madrid, see (Hoyas and Jiménez 2006), is used for the simulations. Due to the lack of experimental and DNS data, the convergence of every simulation has been validated using the total shear stress equation and the relation between the friction velocities at the lower and upper wall. Examining the spectra we found that the large and wide structures, which appear in pure Couette flow, see (Avsarkisov et al. 2014), are destroyed as soon as transpiration velocity is different from zero. This and the presence of anomalous spectra near the blowing wall indicates the strong influence of suction on the whole flow, which was observed in (Antonia et al. 1988) as well. As classical scaling laws are not valid due to transpiration, new scaling laws of the mean velocity are derived using Lie symmetry methods. Additionally, suction creates a comparably larger uτ which, in turn, causes a flat and long region in the indicator function for the largest transpiration rate. SH was partially funded by ENE2015-71333-R. SK was funded by DFG under Grant No. OB96/39-1. Computer resources have been provided by LRZ Munich under Grant pr92la.

  5. The dynamics of embolism refilling in abscisic acid (ABA)-deficient tomato plants.

    Science.gov (United States)

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

    2012-12-24

    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.

  6. Dominant controls of transpiration along a hillslope transect inferred from ecohydrological measurements and thermodynamic limits

    Science.gov (United States)

    Renner, Maik; Hassler, Sibylle K.; Blume, Theresa; Weiler, Markus; Hildebrandt, Anke; Guderle, Marcus; Schymanski, Stanislaus J.; Kleidon, Axel

    2016-05-01

    We combine ecohydrological observations of sap flow and soil moisture with thermodynamically constrained estimates of atmospheric evaporative demand to infer the dominant controls of forest transpiration in complex terrain. We hypothesize that daily variations in transpiration are dominated by variations in atmospheric demand, while site-specific controls, including limiting soil moisture, act on longer timescales. We test these hypotheses with data of a measurement setup consisting of five sites along a valley cross section in Luxembourg. Both hillslopes are covered by forest dominated by European beech (Fagus sylvatica L.). Two independent measurements are used to estimate stand transpiration: (i) sap flow and (ii) diurnal variations in soil moisture, which were used to estimate the daily root water uptake. Atmospheric evaporative demand is estimated through thermodynamically constrained evaporation, which only requires absorbed solar radiation and temperature as input data without any empirical parameters. Both transpiration estimates are strongly correlated to atmospheric demand at the daily timescale. We find that neither vapor pressure deficit nor wind speed add to the explained variance, supporting the idea that they are dependent variables on land-atmosphere exchange and the surface energy budget. Estimated stand transpiration was in a similar range at the north-facing and the south-facing hillslopes despite the different aspect and the largely different stand composition. We identified an inverse relationship between sap flux density and the site-average sapwood area per tree as estimated by the site forest inventories. This suggests that tree hydraulic adaptation can compensate for heterogeneous conditions. However, during dry summer periods differences in topographic factors and stand structure can cause spatially variable transpiration rates. We conclude that absorption of solar radiation at the surface forms a dominant control for turbulent heat and

  7. Toward an improved understanding of the role of transpiration in critical zone dynamics

    Science.gov (United States)

    Mitra, B.; Papuga, S. A.

    2012-12-01

    Evapotranspiration (ET) is an important component of the total water balance across any ecosystem. In subalpine mixed-conifer ecosystems, transpiration (T) often dominates the total water flux and therefore improved understanding of T is critical for accurate assessment of catchment water balance and for understanding of the processes that governs the complex dynamics across critical zone (CZ). The interaction between T and plant vegetation not only modulates soil water balance but also influences water transit time and hydrochemical flux - key factors in our understanding of how the CZ evolves and responds. Unlike an eddy covariance system which provides only an integrated ET flux from an ecosystem, a sap flow system can provide an estimate of the T flux from the ecosystem. By isolating T, the ecohydrological drivers of this major water loss from the CZ can be identified. Still, the species composition of mixed-conifer ecosystems vary and the drivers of T associated with each species are expected to be different. Therefore, accurate quantification of T from a mixed-conifer requires knowledge of the unique transpiration dynamics of each of the tree species. Here, we installed a sap flow system within two mixed-conifer study sites of the Jemez River Basin - Santa Catalina Mountains Critical Zone Observatory (JRB - SCM CZO). At both sites, we identified the dominant tree species and installed sap flow sensors on healthy representatives for each of those species. At the JRB CZO site, sap sensors were installed in fir (4) and spruce (4) trees; at the SCM CZO site, sap sensors were installed at white fir (4) and maple (4) and one dead tree. Meteorological data as well as soil temperature (Ts) and soil moisture (θ) at multiple depths were also collected from each of the two sites. Preliminary analysis of two years of sap flux rate at JRB - SCM CZO shows that the environmental drivers of fir, spruce, and maple are different and also vary throughout the year. For JRB fir

  8. respiration and transpiration characteristics of selected fresh fruits ...

    African Journals Online (AJOL)

    AISA

    Key words : packaging, respiration, transpiration, temperature, relative humidity. RESUME ... microbial attack. Shelf life is inversely ... of relative humidity. MATERIALS AND METHODS ..... physiology and crop preservation. (M.) Lieberman ed.

  9. Risk-taking plants

    Science.gov (United States)

    Sade, Nir; Gebremedhin, Alem; Moshelion, Menachem

    2012-01-01

    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 (Ψleaf) when water is abundant, as well as under drought conditions, by reducing stomatal conductance as necessary to limit transpiration. Anisohydric plants have more variable Ψleaf 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

  10. Desiccant cooling using unglazed transpired solar collectors

    Science.gov (United States)

    Pesaran, A. A.; Wipke, K.

    1992-05-01

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

  11. Anatomical Basis for Optimal Use of Water for Maintenance of Three Xerophytic Plants

    OpenAIRE

    Abdullahi Alanamu ABDULRAHAMAN; Felix Ayotunde OLADELE

    2012-01-01

    Three xerophytic plant species namely Agave americana Linn., Aloe vera Tourn. and Linn. and Euphorbia milii Des Moul. were propagated in a greenhouse each with 5 varying soil moisture contents i.e. 1.25%, 2.5%, 5%, 10%, and 20% and subjected to 4 watering frequencies i.e. daily, weekly, biweekly and monthly. Euphorbia milii was the most xerophytic species having relatively lower rate of transpiration than Aloe vera and Agave americana. It was suggested that the high rate of transpiration in A...

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

    Directory of Open Access Journals (Sweden)

    Francesca Secchi

    2012-12-01

    Full Text Available 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.

  13. Advances in the two-source energy balance model:Partioning of evaporation and transpiration for row crops

    Science.gov (United States)

    Accurate partitioning of the evaporation (E) and transpiration (T) components of evapotranspiration (ET) in remote sensing models is important for evaluating strategies aimed at increasing crop water productivity. The two-source energy balance (TSEB) model solves the energy balance of the soil-plant...

  14. Advances in the two-source energy balance model: Partioning of evaporation and transpiration for row crops for cotton

    Science.gov (United States)

    Accurate partitioning of the evaporation (E) and transpiration (T) components of evapotranspiration (ET) in remote sensing models is important for evaluating strategies aimed at increasing crop water productivity. The two-source energy balance (TSEB) model solves the energy balance of the soil-plant...

  15. Comparing the Penman-Monteith equation and a modified Jarvis-Stewart model with an artificial neural network to estimate stand-scale transpiration and canopy conductance

    Science.gov (United States)

    Whitley, Rhys; Medlyn, Belinda; Zeppel, Melanie; Macinnis-Ng, Catriona; Eamus, Derek

    2009-06-01

    SUMMARYThe responses of canopy conductance to variation in solar radiation, vapour pressure deficit and soil moisture have been extensively modelled using a Jarvis-Stewart (JS) model. Modelled canopy conductance has then often been used to predict transpiration using the Penman-Monteith (PM) model. We previously suggested an alternative approach in which the JS model is modified to directly estimate transpiration rather than canopy conductance. In the present study we used this alternative approach to model tree water fluxes from an Australian native forest over an annual cycle. For comparative purposes we also modelled canopy conductance and estimated transpiration via the PM model. Finally we applied an artificial neural network as a statistical benchmark to compare the performance of both models. Both the PM and modified JS models were parameterised using solar radiation, vapour pressure deficit and soil moisture as inputs with results that compare well with previous studies. Both models performed comparably well during the summer period. However, during winter the PM model was found to fail during periods of high rates of transpiration. In contrast, the modified JS model was able to replicate observed sapflow measurements throughout the year although it too tended to underestimate rates of transpiration in winter under conditions of high rates of transpiration. Both approaches to modelling transpiration gave good agreement with hourly, daily and total sums of sapflow measurements with the modified JS and PM models explaining 87% and 86% of the variance, respectively. We conclude that these three approaches have merit at different time-scales.

  16. Tree sap flow and stand transpiration of two Acacia mangium plantations in Sabah, Borneo

    Science.gov (United States)

    Cienciala, E.; Kučera, J.; Malmer, A.

    2000-09-01

    Water use of Acacia mangium trees grown in plantations was measured by a heat balance method in two stands that largely differed in tree density. Tree sap flow was closely coupled to climatic drivers and responded with minimal time delay. Using no time shift, sap flow rate could be tightly fitted to a simple equation that combined a parabolic response to radiation and an inverse linear response to air humidity. On the contrary, the analysis of canopy conductance showed no meaningful response to either individual or combined microclimatic variables. No indication of water deficit was observed, though the measurement period was during the dry period of the year. The measurements indicate a minimal diurnal use of water stored in plant tissues. The difference in tree water use from the two studied stands was effectively scaled by tree sapwood area. Canopy transpiration of the densest stand reached in average 3.9 mm d -1 compared with 2.7 mm d -1 for the stand representing the average conditions in the catchment.

  17. An Integrated View of Whole-Tree Hydraulic Architecture. Does Stomatal or Hydraulic Conductance Determine Whole Tree Transpiration?

    Directory of Open Access Journals (Sweden)

    Juan Rodríguez-Gamir

    Full Text Available Hydraulic conductance exerts a strong influence on many aspects of plant physiology, namely: transpiration, CO2 assimilation, growth, productivity or stress response. However we lack full understanding of the contribution of root or shoot water transport capacity to the total water balance, something which is difficult to study in trees. Here we tested the hypothesis that whole plant hydraulic conductance modulates plant transpiration using two different seedlings of citrus rootstocks, Poncirus trifoliata (L. Raf. and Cleopatra mandarin (Citrus reshni Hort ex Tan.. The two genotypes presented important differences in their root or shoot hydraulic conductance contribution to whole plant hydraulic conductance but, even so, water balance proved highly dependent on whole plant conductance. Further, we propose there is a possible equilibrium between root and shoot hydraulic conductance, similar to that between shoot and root biomass production, which could be related with xylem anatomy.

  18. An Integrated View of Whole-Tree Hydraulic Architecture. Does Stomatal or Hydraulic Conductance Determine Whole Tree Transpiration?

    Science.gov (United States)

    Rodríguez-Gamir, Juan; Primo-Millo, Eduardo; Forner-Giner, María Ángeles

    2016-01-01

    Hydraulic conductance exerts a strong influence on many aspects of plant physiology, namely: transpiration, CO2 assimilation, growth, productivity or stress response. However we lack full understanding of the contribution of root or shoot water transport capacity to the total water balance, something which is difficult to study in trees. Here we tested the hypothesis that whole plant hydraulic conductance modulates plant transpiration using two different seedlings of citrus rootstocks, Poncirus trifoliata (L.) Raf. and Cleopatra mandarin (Citrus reshni Hort ex Tan.). The two genotypes presented important differences in their root or shoot hydraulic conductance contribution to whole plant hydraulic conductance but, even so, water balance proved highly dependent on whole plant conductance. Further, we propose there is a possible equilibrium between root and shoot hydraulic conductance, similar to that between shoot and root biomass production, which could be related with xylem anatomy.

  19. Changes in the physiological regulation of transpiration caused by the effects of industrial air pollution. [Cucumis sativus

    Energy Technology Data Exchange (ETDEWEB)

    Kozinka, V.; Klasova, A.; Niznansky, A.

    1963-01-01

    Through Hygen's method of quantitative analysis of transpiration curves, the authors studied the intensity of stomatal and cuticular transpiration of germinating leaves of Cucumis sativus which were experimentally exposed to solid impurities containing F. The difference between the control and experimental plants shows that the impurities not only blocked the regulating system of breathing but also caused increased cuticular transpiration. Numerous lesions were observed; cuticle damage also spread to the inner tissues. A direct relationship between microscopic and macroscopic symptoms was not proven. The creation of conditions adverse to the normal development of the water balance was intensified when the impurities were dropped onto the surface of the leaves. The possible protective function of trichomes is mentioned, but applies only when the impurities settle on a dry surface.

  20. Fluorometric Measurement of Individual Stomata Activity and Transpiration via a “Brush-on”, Water-Responsive Polymer

    Science.gov (United States)

    Seo, Minjeong; Park, Dong-Hoon; Lee, Chan Woo; Jaworski, Justyn; Kim, Jong-Man

    2016-08-01

    Much of atmospheric water originates from transpiration, the process by which plants release H2O from pores, known as stomata, that simultaneously intake CO2 for photosynthesis. Controlling stomatal aperture can regulate the extent of water transport in response to dynamic environmental factors including osmotic stress, temperature, light, and wind. While larger leaf regions are often examined, the extent of water vapor release from individual stomata remains unexplored. Using a “brush-on” sensing material, we can now assess transpiration using a water-responsive, polydiacetylene-based coating on the leaves surfaces. By eliciting a fluorometric signal to passing water vapor, we obtained information regarding the activity of individual stomata. In this demonstration, our results prove that this coating can identify the proportion of active stomata and the extent of transpirational diffusion of water in response to different conditions.

  1. Determination of actual evapotranspiration and transpiration in desert sand dunes (Negev Desert) using different approaches

    Institute of Scientific and Technical Information of China (English)

    Thomas Littmann; Maik Veste

    2006-01-01

    In an arid environment, especially in sandy areas where surface runoff is of no practical importance in the hydrological budget, it is rainfall, dewfall and evapotranspiration that become the most important variables. To assess actual evapotranspiration,several methods (flux-gradient, BREB, eddy correlation) were applied to data from the Nizzana experimental site in the northwestern Negev Desert. Additionally, a model specifically designed for arid environments is introduced in this paper. This zero plane model shows the most reasonable results compared with the other methods, which overestimate evapotranspiration to a large degree. It is shown that plant transpiration is the dominant process in total evapotranspiration while advective processes do not play a major role in the near-ground boundary layer, although the study area is influenced by a sea breeze. Actual transpiration of Artemisia monosperma was measured in a field experiment to validate the calculated evapotranspiration. The vegetation contributed 41% of the calculated total evapotranspiration in a single month.

  2. Effects of increased atmospheric CO{sub 2} concentrations on transpiration of a wheat field in consideration of water and nitrogen limitation; Die Wirkung von erhoehten atmosphaerischen CO{sub 2}-Konzentrationen auf die Transpiration eines Weizenbestandes unter Beruecksichtigung von Wasser- und Stickstofflimitierung

    Energy Technology Data Exchange (ETDEWEB)

    Grossman-Clarke, S.

    2000-09-01

    Primary responses of C{sub 3}-plants to elevated atmospheric CO{sub 2} concentrations are an increase in the net assimilation rate, leading to greater biomass, and an associated decrease in the transpiration rate per unit leaf area due to CO{sub 2}-induced stomatal closure. The question has therefore arisen: does canopy transpiration increase because of the greater biomass, or decrease because of the stomatal closure? The direct impact of an elevated atmospheric CO{sub 2} concentration of 550 {mu}mol mol{sup -1} on the seasonal course of canopy transpiration of a spring wheat crop was investigated by means of the simulation model DEMETER for production under unlimited water and nutrient supply, production under limited water but unlimited nutrient supply and the production under unlimited water but limited nitrogen supply. Independent data of the free-air carbon dioxide enrichment wheat experiments in Arizona, USA (1993-96) were used to test if the model is able to make reasonable predictions of water use and productivity of the spring wheat crop using only parameters derived from the literature. A model integrating leaf photosynthesis, stomatal conductance and energy fluxes between the plant and the atmosphere was scaled to a canopy level in order to be used in the wheat crop growth model. Temporal changes of the model parameters were considered by describing them as dependent on the changing leaf nitrogen content. Comparison of the simulation and experimental results showed that the applicability of the model approach was limited after anthesis by asynchronous changes in mesophyll and stomatal conductance. Therefore a new model approach was developed describing the interaction between assimilation rate and stomatal conductance during grain filling. The simulation results revealed only small differences in the cumulative sum of canopy transpiration and soil evaporation between elevated CO{sub 2} and control conditions. For potential growth conditions the model

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1998-12-31

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

  4. Experimental study on a transpiration cooling thermal protection system

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Transpiration cooling thermal protection systems (TPS) are investigated for potential applications in hypersonic and re-entry vehicles,which are subjected to the severe aerodynamic heating environment. In this paper a transpiration cooling thermal protection system was designed and manufactured,and an experiment platform with radiant heating at the bottom as heat source was developed. The cooling capacity of the transpiration cooling TPS was experimentally investigated. By combining transpiration cooling method with traditional TPS,the heat load capability of the TPS can be improved. The structure temperature with active cooling applied was much lower than that without active cooling applied under the same heat load as well as the heat load increased with active cooling than the one without active cooling for the same structure temperature. The experimental results showed that at 5800 s,the temperature of inner structure was 100°C with active cooling applied compared to 500°C without active cooling applied,then the temperature increased and reached to 360°C at 8300 s. Heat load of this transpiration cooling TPS can be increased by over 70% as compared to the passion one and the cooling capability of the transpiration TPS was about 1700 kJ/kg. The results can provide fundamental data for developing the transpiration cooling TPS.

  5. Relative rates of synonymous substitutions in the mitochondrial, chloroplast and nuclear genomes of seed plants.

    Science.gov (United States)

    Drouin, Guy; Daoud, Hanane; Xia, Junnan

    2008-12-01

    Previous studies have estimated that, in angiosperms, the synonymous substitution rate of chloroplast genes is three times higher than that of mitochondrial genes and that of nuclear genes is twelve times higher than that of mitochondrial genes. Here we used 12 genes in 27 seed plant species to investigate whether these relative rates of substitutions are common to diverse seed plant groups. We find that the overall relative rate of synonymous substitutions of mitochondrial, chloroplast and nuclear genes of all seed plants is 1:3:10, that these ratios are 1:2:4 in gymnosperms but 1:3:16 in angiosperms and that they go up to 1:3:20 in basal angiosperms. Our results show that the mitochondrial, chloroplast and nuclear genomes of seed plant groups have different synonymous substitutions rates, that these rates are different in different seed plant groups and that gymnosperms have smaller ratios than angiosperms.

  6. Photochemical Reflectance Index (PRI) as a proxy of Light Use Efficiency (LUE) and transpiration in Mediterranean crop sites

    Science.gov (United States)

    LE Dantec, V.; Chebbi, W.; Boulet, G.; Merlin, O.; Lili-Chabaane, Z.; Er Raki, S.; Ceschia, E.; Khabba, S.; Fanise, P.; Zawilski, B.; Simonneaux, V.; Jarlan, L.

    2016-12-01

    The Photochemical Reflectance Index (PRI) is based on the short term reversible xanthophyll pigment changes accompanying plant stress and therefore of the associated photosynthetic activities. Strong relationships between PRI and Light Use Efficiency (LUE) were shown at leaf and canopy scales and over a wide range of species (Garbulsky et al., 2011). But very few previous works have explored the potential link with plant water status. In this study, we have first analyzed the link between PRI and LUE at canopy scale on two different crops in terms of canopy structure and crop management: olive grove (Tunisia) and wheat grown under different water regimes (irrigated or rainfed) and climate zones (France, Morocco). We have investigated the daily and seasonal dynamics of PRI; linking its variations to meteorological factors (global radiation and sun angle effects, soil water content, relative air humidity …) and plant processes. The highest correlations were mainly observed in clear skies conditions. We have found, whatever site, linear negative relationships between PRI and LUE using data acquired in midday (i.e. in solar zenithal angle condition). Linear link between PRI and sapflow measurements was also revealed. This correlation was obtained over periods characterized by a moderate soil water deficit, i.e. by when transpiration rate was mainly control by Vapor Pressure Deficit. We will then briefly presented alternative and complementary approaches to this index, to detect different level of water stress using thermal infrared emissions.

  7. The effect of water availability on stand-level productivity, transpiration, water use efficiency and radiation use efficiency of field-grown willow clones

    DEFF Research Database (Denmark)

    Linderson, Maj-Lena; Iritz, Z.; Lindroth, A.

    2007-01-01

    The effect of water availability on stand-level productivity, transpiration, water use efficiency (WUE) and radiation use efficiency (RUE) is evaluated for different willow clones at stand level. The measurements were made during the growing season 2000 in a 3-year-old plantation in Scania......-flow and biometry are up-scaled to stand transpiration and stand dry substance production and used to assess WUE. RUE is estimated from the ratio between the stand dry substance production and the accumulated absorbed photosynthetic active radiation over the growing season. The total stand transpiration rate...

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

    Science.gov (United States)

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

    2009-10-01

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

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

    Science.gov (United States)

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

    2009-10-01

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

  10. Influence of Soil Compaction and Drought on the Growth,Photosynthesis and Carbohydrates in Fugi/M.9EMLA Apple Plants

    Institute of Scientific and Technical Information of China (English)

    YAO Yun-cong; John G Streeter; David C Ferree

    2003-01-01

    Greenhouse-grown 1-year-old potted M.9EMLA apple trees (Malus pumila Borkh) were subjected to the soil compaction and, after growing under compacted or non-compacted conditions for 6 weeks, were subjected to drought stress by withholding water for an additional six-week period. Soil compaction and drought stress significantly reduced plant height, number of leaves, and leaf area. Although drought significantly inhibited photosynthesis and transpiration, compaction only depressed transpiration. Furthermore, the effects of drought on plant growth, photosynthesis and transpiration were much greater than the effects of compaction. The rate of water loss from compacted plants was lower than the rate from non-compacted controls and this may explain the insignificant impact of compaction on photosynthesis. Sorbitol, glucose, and fructose concentrations increased over time during the drought stress period whereas sucrose concentration declined. In well-watered controls, sucrose concentration was much higher in leaves of compacted plants than in the leaves on non-compacted controls. For most of the sampling dates the leaf sorbitol concentration was lower in leaves on plants growing in compacted soil than in the leaves of those of the non-compacted controls. Although interactions between the effects of compaction and drought were highly significant for plant growth variables during the onset of drought, interactive effects on photosynthesis, transpiration, relative water content and carbohydrate variables were inconsistent. Compaction and drought both have major effects on apple plants and the interactions between these two stresses are complex.

  11. Canopy Transpiration and Stomatal Responses to Prolonged Drought by a Dominant Desert Species in Central Asia

    Directory of Open Access Journals (Sweden)

    Daxing Gu

    2017-06-01

    Full Text Available In arid and semiarid lands, canopy transpiration and its dynamics depend largely on stomatal sensitivity to drought. In this study, the sap flow of a dominant species, Haloxylon ammodendron growing in Central Asian deserts, was monitored using Granier-type sensors, from which the canopy stomatal conductance was derived. The responses of canopy transpiration and stomatal conductance to environmental variables during the second half of the growing season, when annual prolonged drought occurred, was analyzed for four continuous years, from 2013 to 2016. A soil water content (SWC of 3% was identified as the lower soil water threshold for this species, below which the plant lost the ability for stomatal regulation on water loss and suffered the risk of mortality. Above this threshold, the sensitivity of canopy transpiration to vapor pressure deficit, VPD (K, was linearly correlated with SWC, which mainly resulted from different stomatal behaviors at varying drought intensities. Stomatal sensitivity to VPD (m/Gsref increased linearly with soil moisture deficit, inducing a shift from more anisohydric to a more isohydric stomatal behavior. The flexibility of stomatal behavior regarding soil drought was one key element facilitating the survival of H. ammodendron in such an extreme dry environment.

  12. Effects of pruning intensity on jujube transpiration and soil moisture of plantation in the Loess Plateau

    Science.gov (United States)

    Nie, Zhenyi; Wang, Xing; Wang, Youke; Ma, Jianpeng; Wei, Xinguang; Chen, Dianyu

    2017-01-01

    In order to ease soil desiccation and prevent ecological deterioration in the Loess Plateau, where jujube (Zizyphus jujube MIll) is widely cultivated as a drought tolerant plant, four pruning intensities (PI), from PI-1 (light) to PI-4 (heavy) were set up based on total length of secondary branches to study the effects of pruning on transpiration and soil moisture in jujube plantations. Furthermore, growth indexes were regularly monitored to estimate jujubes biomass. Sap flow, meteorological and soil moisture conditions were monitored using thermal dissipation probes (TDP), weather station (RR-9100) and the combination of time domain transmission (TDT) technology and neutron moisture gauges (CNC503B), respectively. The results showed that daily actual transpiration of jujube was positively correlated with leaf biomass. Compared with PI-1, jujube transpiration during growth period under PI-2, PI-3, and PI-4 dropped by 11.1%, 29.2%, and 47.9%, respectively. On the contrary, annual water storage under PI-2, PI-3, and PI-4 increased by 6.29 mm, 25.78 mm and 34.74 mm while water use efficiency increased by 5.1%, 15.7% and 24.2%, respectively. Overall, increase in pruning intensity could significantly reduce water consumption of jujube and improve soil moisture in jujube plantations.

  13. Transpiration and leaf growth of potato clones in response to soil water deficit

    Directory of Open Access Journals (Sweden)

    André Trevisan de Souza

    2014-04-01

    Full Text Available Potato (Solanum tuberosum ssp. Tuberosum crop is particularly susceptible to water deficit because of its small and shallow root system. The fraction of transpirable soil water (FTSW approach has been widely used in the evaluation of plant responses to water deficit in different crops. The FTSW 34 threshold (when stomatal closure starts is a trait of particular interest because it is an indicator of tolerance to water deficit. The FTSW threshold for decline in transpiration and leaf growth was evaluated in a drying soil to identify potato clones tolerant to water deficit. Two greenhouse experiments were carried out in pots, with three advanced clones and the cultivar Asterix. The FTSW, transpiration and leaf growth were measured on a daily basis, during the period of soil drying. FTSW was an efficient method to separate potato clones with regard to their response to water deficit. The advancedclones SMINIA 02106-11 and SMINIA 00017-6 are more tolerant to soil water deficit than the cultivar Asterix, and the clone SMINIA 793101-3 is more tolerant only under high solar radiation.

  14. Simulation Experiment about Transpiration Characteristics of Phragmites australis Leaf in Liaohe Estuary Wetlands%辽河口湿地芦苇叶片蒸腾及其与影响因子关系研究

    Institute of Scientific and Technical Information of China (English)

    张颖; 郑西来; 伍成成; 李琴

    2011-01-01

    The objective of this study is to analysis the transpiration characteristics of Phragmites australis leaf and the relationships between the leaf transpiration and influence factors at different water levels, and to improve plant water use efficient and provide a theoretical basis of ecological water requirement of plant. The simulation experiment was done by containers with Phragmites australis leaf in the field of Liaohe Estuary in August-October 2009.The water levels were controlled and the transpiration rate of Phragmites australis leaf was measured by a portable steady-state porometer (PM-5). The results showed that the diurnal courses of the transpiration rates of Phragmites australis leaf were different for different water depths. The diurnal courses of the leaf transpiration rate all displayed a single peak pattern when the water depth was 10 cm above soil surface, there was no noon break which was caused by the close of stoma. The peak of the leaf transpiration rate occurred at about 14100. The leaf transpiration rate decreased if Phragmites australis were submerged in water for a long time. When the levels of the grounder water were 5 cm, 20 cm, 40 cm and 60 cm under soil surface, the diurnal courses of the leaf transpiration rate displayed a double peak pattern, there were lower values at 11: 00-13:00 resulted from the close of stoma. At the same period there was a maximum value of the leaf transpiration rate when the water level was 20 cm under soil surface. There was a similarity in the variation curve of the leaf transpiration rate and stomatal conductance with good correlation in the study. The leaf transpiration rate of Phragmites australis was affected by photosynthetic active radiation and relative humidity, and the latter was the main factor at different ground water depths.%于2009年8~10月,在辽河口芦苇(Phragmites australis)沼泽地,采用野外培养箱土培模拟实验方法,人为控制水位,用PM-5型稳态气孔计测量了不

  15. Plant functional diversity increases grassland productivity-related water vapor fluxes: an Ecotron and modeling approach.

    Science.gov (United States)

    Milcu, Alexandru; Eugster, Werner; Bachmann, Dörte; Guderle, Marcus; Roscher, Christiane; Gockele, Annette; Landais, Damien; Ravel, Olivier; Gessler, Arthur; Lange, Markus; Ebeling, Anne; Weisser, Wolfgang W; Roy, Jacques; Hildebrandt, Anke; Buchmann, Nina

    2016-08-01

    The impact of species richness and functional diversity of plants on ecosystem water vapor fluxes has been little investigated. To address this knowledge gap, we combined a lysimeter setup in a controlled environment facility (Ecotron) with large ecosystem samples/monoliths originating from a long-term biodiversity experiment (The Jena Experiment) and a modeling approach. Our goals were (1) quantifying the impact of plant species richness (four vs. 16 species) on day- and nighttime ecosystem water vapor fluxes; (2) partitioning ecosystem evapotranspiration into evaporation and plant transpiration using the Shuttleworth and Wallace (SW) energy partitioning model; and (3) identifying the most parsimonious predictors of water vapor fluxes using plant functional-trait-based metrics such as functional diversity and community weighted means. Daytime measured and modeled evapotranspiration were significantly higher in the higher plant diversity treatment, suggesting increased water acquisition. The SW model suggests that, at low plant species richness, a higher proportion of the available energy was diverted to evaporation (a non-productive flux), while, at higher species richness, the proportion of ecosystem transpiration (a productivity-related water flux) increased. While it is well established that LAI controls ecosystem transpiration, here we also identified that the diversity of leaf nitrogen concentration among species in a community is a consistent predictor of ecosystem water vapor fluxes during daytime. The results provide evidence that, at the peak of the growing season, higher leaf area index (LAI) and lower percentage of bare ground at high plant diversity diverts more of the available water to transpiration, a flux closely coupled with photosynthesis and productivity. Higher rates of transpiration presumably contribute to the positive effect of diversity on productivity.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1995-09-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1995-09-01

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

  18. Relationship between hexokinase and the aquaporin PIP1 in the regulation of photosynthesis and plant growth.

    Directory of Open Access Journals (Sweden)

    Gilor Kelly

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

  19. Determination of methane emission rates on a biogas plant using data from laser absorption spectrometry.

    Science.gov (United States)

    Groth, Angela; Maurer, Claudia; Reiser, Martin; Kranert, Martin

    2015-02-01

    The aim of the work was to establish a method for emission control of biogas plants especially the observation of fugitive methane emissions. The used method is in a developmental stage but the topic is crucial to environmental and economic issues. A remote sensing measurement method was adopted to determine methane emission rates of a biogas plant in Rhineland-Palatinate, Germany. An inverse dispersion model was used to deduce emission rates. This technique required one concentration measurement with an open path tunable diode laser absorption spectrometer (TDLAS) downwind and upwind the source and basic wind information, like wind speed and direction. Different operating conditions of the biogas plant occurring on the measuring day (December 2013) could be represented roughly in the results. During undisturbed operational modes the methane emission rate averaged 2.8 g/s, which corresponds to 4% of the methane gas production rate of the biogas plant.

  20. Estimates of Radiation Dose Rates Near Large Diameter Sludge Containers in T Plant

    CERN Document Server

    Himes, D A

    2002-01-01

    Dose rates in T Plant canyon during the handling and storage of large diameter storage containers of K Basin sludge were estimated. A number of different geometries were considered from which most operational situations of interest can be constructed.

  1. Pressure effect on rate of production of glucose-equivalent in plant cells

    Indian Academy of Sciences (India)

    Anirban Panda; Surjendu Bhattacharyya; Sambhu N Datta

    2009-07-01

    The rate of glucose equivalent production in C4 green plants is investigated as a function of the intercellular partial pressure of CO2, so as to find the precise physical chemistry of photosynthesis. Expressions are first formulated for the dependence of photochemical efficiency and of rubisco activation on pressure. Then a pressure-dependent rate law is derived. The latter is successfully tested for two specific C4 plants, namely, Panicum antidotale and Panicum coloratum.

  2. Transpired Solar Collector at NREL's Waste Handling Facility Uses Solar Energy to Heat Ventilation Air (Fact Sheet)

    Energy Technology Data Exchange (ETDEWEB)

    2010-09-01

    The transpired solar collector was installed on NREL's Waste handling Facility (WHF) in 1990 to preheat ventilation air. The electrically heated WHF was an ideal candidate for the this technology - requiring a ventilation rate of 3,000 cubic feet per meter to maintain safe indoor conditions.

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

    Science.gov (United States)

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

    2014-01-30

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

  4. The Soil-Plant-Atmosphere Continuum of Mangroves: A Simple Ecohydrological model

    Science.gov (United States)

    Perri, Saverio; Viola, Francesco; Valerio Noto, Leonardo; Molini, Annalisa

    2016-04-01

    Mangroves represent the only forest able to grow at the interface between a terrestrial and a marine habitat. Although globally they have been estimated to account only for 1% of carbon sequestration from forests, as coastal ecosystems they account for about 14% of carbon sequestration by the global ocean. Despite the continuously increasing number of hydrological and ecological field observations, the ecohydrology of mangroves remains largely understudied. Modeling mangrove response to variations in environmental conditions needs to take into account the effect of waterlogging and salinity on transpiration and CO2 assimilation. However, similar ecohydrological models for halophytes are not yet documented in the literature. In this contribution we adapt a Soil-Plant-Atmosphere Continuum (SPAC) model to the mangrove ecosystems. Such SPAC model is based on a macroscopic approach and the transpiration rate is hence obtained by solving the plant and leaf water balance and the leaf energy balance, taking explicitly into account the role of osmotic water potential and salinity in governing plant resistance to water fluxes. Exploiting the well-known coupling of transpiration and CO2 exchange through the stomatal conductance, we also estimate the CO2 assimilation rate. The SPAC is hence tested against experimental data obtained from the literature, showing the reliability and effectiveness of this minimalist approach in reproducing observed processes. Results show that the developed SPAC model is able to realistically simulate the main ecohydrological traits of mangroves, indicating the salinity as a crucial limiting factor for mangrove trees transpiration and CO2 assimilation.

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

    Science.gov (United States)

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

    2015-01-01

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

  6. Shoot Apex Demand Determines Assimilate and Nutrients Partitioning and Nutrient-uptake Rate in Tobacco Plants

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Our previous experiment revealed that apex-removed plants have larger root systems but a lower K+-uptake rates than intact tobacco plants.Since the apex is not only e center of growth and metabolism,but also an important place of auxin synthesis and export,the aims of this study were to distinguish whether the apex demand or auxin synthesized in the apex regulates assimilate and nutrients partitioning within plant,and to explain the reason for the lower K+-uptake rate of the apex-ramoved plant.In comparison with the control plant,covering the shoot apex with a black transparent plastic bag reduced net increases In dry matter and nutrients;however,the distribution of the dry matter and nutrients between shoot and roots and nutrient-uptake rates were not changed.Removal of the shoot apex shifted the dry mass and nutrients distributions to roots,and reduced the rate of nutrient uptake.Application of 1-naphthylacetic acid(NAA) could partly replace the role of the removed apex,stimulated assimilate and nutrient deposition into the treated tissue,and enhanced the reduced plasma membrane ATPase activity of roots to the control level.However,treatment of the apex-removed plants with NAA could not rescue the reduced nutrient uptake rate and the shifted assimilates and nutrients partitioning caused by excision of the apex.Higher nutrient uptake rate of the intact plants could not be explained by root growth parameters,such as total root surface area and number of root tips.The results from the present study indicate that strong apex demand determined assimilatas and nutrients partitioning and nutrient-uptake rate in tobacco(Nicotiana tabacum)plants.

  7. 不同种类抗蒸腾叶面肥对山杏水分利用效率的影响%Impact of Types of Anti-transpirant Foliar Fertilizer on the Water Use Efficiency of Prunus armeniaca

    Institute of Scientific and Technical Information of China (English)

    吴凤; 郭建斌; 李志洪; 吴玉晴; 白晓敏

    2013-01-01

    Resistance control action about anti-transpiration foliar fertilization to the water use efficiency (WUE) were studied in order to enhance the plant survival. By using the pot method, the tests were conducted to Prunus armeniaca L. with different foliar fertilizers under conditions of sufficient water supply. The net photosynthetic rate (Pn), transpiration rate (Tr) of Prunus armeniaca L and their environmental factors were measured so as to get the water use efficiency (WUE) indicators by Pn/Tr. The results showed that net photosynthetic rate (Pn) and transpiration rate (Tr) had two peaks at respectively during the daylightunder the treatments of different foliar fertilizer density with midday depression phenomenon. WUE' maximum presented at 8:00 and the WUE got a trough from 10:00 to 16:00, and the period remained stable, after 16:00, it gradually increased. It showed that WUE reached the highest while WUE of comparison was the minimum when used the A of foliar fertilization. The final study results showed that best formulation was type A, so under the arid conditions, we can choose to spray type A of foliar fertilization on leaf surface to improve plant water use efficiency (WUE) , and improve survival rate of stock. Spraying the anti-transpiration foliar fertilization on leaf surface can not only provide the necessary nutrients required for plant growth, but also inhibit plant transpiration, improve plant water use efficiency (WUE), and improve the survivability of plants to some extent.%研究抗蒸腾叶面肥对苗木水分利用效率的调节作用,可为提高苗木成活率提供参考.采用盆栽法试验,在充分供水的条件下,用不同叶面肥对山杏进行处理,对山杏苗木叶片净光合速率(Pn)、蒸腾速率(Tr)等水分生理指标及其相应的环境因子进行测定.结果表明:不同叶面肥处理下,山杏的净光合速率、蒸腾速率日变化都呈双峰曲线,且净光合速率日变化曲线存在光合午休

  8. Transpiration increases during the dry season: patterns of tree water use in eucalypt open-forests of northern Australia.

    Science.gov (United States)

    O'Grady, A. P.; Eamus, D.; Hutley, L. B.

    1999-07-01

    Australian savannas exhibit marked seasonality in precipitation, with more than 90% of the annual total falling between October and May. The dry season is characterized by declining soil water availability and high vapor pressure deficits (up to 2.5 kPa). We used heat pulse technology to measure whole-tree transpiration rates on a daily and seasonal basis for the two dominant eucalypts at a site near Darwin, Australia. Contrary to expectations, transpiration rates were higher during the dry season than during the wet season, largely because of increased evaporative demand and the exploitation of groundwater reserves by the trees. Transpiration rates exhibited a marked hysteresis in relation to vapor pressure deficit, which was more marked in the dry season than in the wet season. This result may be attributable to low soil hydraulic conductivity, or the use of stored stem water, or both. Tree water use was strongly correlated with leaf area and diameter at breast height and there were no differences in transpiration between the species studied. These results are discussed in relation to scaling tree water use to stand water use.

  9. Modelled hydraulic redistribution by sunflower (Helianthus annuus L.) matches observed data only after including night-time transpiration.

    Science.gov (United States)

    Neumann, Rebecca B; Cardon, Zoe G; Teshera-Levye, Jennifer; Rockwell, Fulton E; Zwieniecki, Maciej A; Holbrook, N Michele

    2014-04-01

    The movement of water from moist to dry soil layers through the root systems of plants, referred to as hydraulic redistribution (HR), occurs throughout the world and is thought to influence carbon and water budgets and ecosystem functioning. The realized hydrologic, biogeochemical and ecological consequences of HR depend on the amount of redistributed water, whereas the ability to assess these impacts requires models that correctly capture HR magnitude and timing. Using several soil types and two ecotypes of sunflower (Helianthus annuus L.) in split-pot experiments, we examined how well the widely used HR modelling formulation developed by Ryel et al. matched experimental determination of HR across a range of water potential driving gradients. H. annuus carries out extensive night-time transpiration, and although over the last decade it has become more widely recognized that night-time transpiration occurs in multiple species and many ecosystems, the original Ryel et al. formulation does not include the effect of night-time transpiration on HR. We developed and added a representation of night-time transpiration into the formulation, and only then was the model able to capture the dynamics and magnitude of HR we observed as soils dried and night-time stomatal behaviour changed, both influencing HR.

  10. Modeled hydraulic redistribution by Helianthus annuus L. matches observed data only after model modification to include nighttime transpiration

    Science.gov (United States)

    Neumann, R. B.; Cardon, Z. G.; Rockwell, F. E.; Teshera-Levye, J.; Zwieniecki, M.; Holbrook, N. M.

    2013-12-01

    The movement of water from moist to dry soil layers through the root systems of plants, referred to as hydraulic redistribution (HR), occurs throughout the world and is thought to influence carbon and water budgets and ecosystem functioning. The realized hydrologic, biogeochemical, and ecological consequences of HR depend on the amount of redistributed water, while the ability to assess these impacts requires models that correctly capture HR magnitude and timing. Using several soil types and two eco-types of Helianthus annuus L. in split-pot experiments, we examined how well the widely used HR modeling formulation developed by Ryel et al. (2002) could match experimental determination of HR across a range of water potential driving gradients. H. annuus carries out extensive nighttime transpiration, and though over the last decade it has become more widely recognized that nighttime transpiration occurs in multiple species and many ecosystems, the original Ryel et al. (2002) formulation does not include the effect of nighttime transpiration on HR. We developed and added a representation of nighttime transpiration into the formulation, and only then was the model able to capture the dynamics and magnitude of HR we observed as soils dried and nighttime stomatal behavior changed, both influencing HR.

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

    Directory of Open Access Journals (Sweden)

    Shirk Andrew J

    2005-12-01

    Full Text Available Abstract 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 in chloroplast and/or nuclear substitution rates and are therefore thought to reflect whole-organism forces rather than ones impinging directly on the mitochondrial mutation rate. Only a single case of extensive, mitochondrial-specific rate changes has been described, in the angiosperm genus Plantago. Results We explored a second potential case of highly accelerated mitochondrial sequence evolution in plants. This case was first suggested by relatively poor hybridization of mitochondrial gene probes to DNA of Pelargonium hortorum (the common geranium. We found that all eight mitochondrial genes sequenced from P. hortorum are exceptionally divergent, whereas chloroplast and nuclear divergence is unexceptional in P. hortorum. Two mitochondrial genes were sequenced from a broad range of taxa of variable relatedness to P. hortorum, and absolute rates of mitochondrial synonymous substitutions were calculated on each branch of a phylogenetic tree of these taxa. We infer one major, ~10-fold increase in the mitochondrial synonymous substitution rate at the base of the Pelargonium family Geraniaceae, and a subsequent ~10-fold rate increase early in the evolution of Pelargonium. We also infer several moderate to major rate decreases following these initial rate increases, such that the mitochondrial substitution rate has returned to normally low levels in many members of the Geraniaceae. Finally, we find unusually little RNA editing of Geraniaceae mitochondrial genes, suggesting high levels of retroprocessing in their

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

    Science.gov (United States)

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

    2000-01-01

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

  13. Climate change: Anti-transpirant effects on grape physiology and berry and wine composition (Vitis Vinifera L.)

    OpenAIRE

    Marallo, Nadia

    2015-01-01

    Plant growth, yield and quality are highly dependent on climate. In the last few decades the trend of increasing global temperatures has affected the accumulation of sugars in berries and hence the degree of alcohol in resultant wines. Therefore numerous studies have considered different agronomic practices that limit photosynthetic activity. The aim of our study was to evaluate the effect of a natural anti-transpirant on grapevine physiology and berry and wine composition on different cultiv...

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

    Energy Technology Data Exchange (ETDEWEB)

    Bachand, P.A.M., E-mail: Philip.Bachand@Tetratech.com [Tetra Tech, Davis, CA (United States); Bachand, S. [Tetra Tech, Davis, CA (United States); Fleck, J.; Anderson, F. [U.S. Geological Survey, California Water Science Center, Sacramento, CA (United States); Windham-Myers, L. [U.S. Geological Survey, National Research Program, Menlo Park, CA (United States)

    2014-06-01

    The current state of science and engineering related to analyzing wetlands overlooks the importance of transpiration and risks data misinterpretation. In response, we developed hydrologic and mass budgets for agricultural wetlands using electrical conductivity (EC) as a natural conservative tracer. We developed simple differential equations that quantify evaporation and transpiration rates using flow rates and tracer concentrations at wetland inflows and outflows. We used two ideal reactor model solutions, a continuous flow stirred tank reactor (CFSTR) and a plug flow reactor (PFR), to bracket real non-ideal systems. From those models, estimated transpiration ranged from 55% (CFSTR) to 74% (PFR) of total evapotranspiration (ET) rates, consistent with published values using standard methods and direct measurements. The PFR model more appropriately represents these non-ideal agricultural wetlands in which check ponds are in series. Using a flux model, we also developed an equation delineating the root zone depth at which diffusive dominated fluxes transition to advective dominated fluxes. This relationship is similar to the Peclet number that identifies the dominance of advective or diffusive fluxes in surface and groundwater transport. Using diffusion coefficients for inorganic mercury (Hg) and methylmercury (MeHg) we calculated that during high ET periods typical of summer, advective fluxes dominate root zone transport except in the top millimeters below the sediment–water interface. The transition depth has diel and seasonal trends, tracking those of ET. Neglecting this pathway has profound implications: misallocating loads along different hydrologic pathways; misinterpreting seasonal and diel water quality trends; confounding Fick's First Law calculations when determining diffusion fluxes using pore water concentration data; and misinterpreting biogeochemical mechanisms affecting dissolved constituent cycling in the root zone. In addition, our

  15. Reduction of lesion growth rate of late blight plant disease in transgenic potato expressing harpin protein

    Institute of Scientific and Technical Information of China (English)

    李汝刚; 范云六

    1999-01-01

    Using harpin protein gene from apple fire blight pathogen Erwinia amylavora and potato prp1-1 promoter as main DNA elements, the feasibility of using pathogen infection-induced hypersensitive response was explored as a new strategy of engineering fungal disease resistance. Three plant transformation vectors were constructed and 68 transgenic potato plants were produced through Agrobacterium mediated transformation method. Southern, Northern and Western blot analysis demonstrated the insertion, transcription and protein expression of harpin protein gene in transgenic plants. Disease resistance test using a complex race of Phytophthora infestans as challenging pathogen showed that both constitutive and pathogen infection-induced expression of harpin protein gene in transgenic potato reduced the lesion growth rate of fungus. Among plants where harpin protein gene expression was induced only by fungus infection, two plants were found to be highly resistant to P. infestans infection. Fungal hyphae were not pr

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

    Science.gov (United States)

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

    2013-05-01

    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 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.

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

    Science.gov (United States)

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

    2013-08-01

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

  18. The effects of exogenous plant growth regulators in the phytoextraction of heavy metals.

    Science.gov (United States)

    Tassi, Eliana; Pouget, Joël; Petruzzelli, Gianniantonio; Barbafieri, Meri

    2008-03-01

    The term "assisted phytoextraction" usually refers to the process of applying a chemical additive to contaminated soil in order to increase the metal uptake by crop plants. In this study three commercially available plant growth regulators (PGRs) based on cytokinins (CKs) were used to boost the assisted phytoextraction of Pb and Zn in contaminated soil collected from a former manufactured gas-plant site. The effects of EDTA treatment in soil and PGR treatment in leaves of Helianthus annuus were investigated in terms of dry weight biomass, Pb and Zn accumulation in the upper parts of the plants, Pb and Zn phytoextraction efficiency and transpiration rate. Metal solubility in soil and its subsequent accumulation in shoots were markedly enhanced by EDTA. The combined effects of EDTA and cytokine resulted in an increase in the Pb and Zn phytoextraction efficiency (up to 890% and 330%, respectively, compared to untreated plants) and up to a 50% increase in foliar transpiration. Our results indicate that exogenous PGRs based on CKs can positively assist the phytoextraction increasing the biomass production, the metal accumulation in shoots and the plant transpiration. The observed increase in biomass could be related to its action in stimulation of cell division and shoot initiation. On the other hand, the increase in metal accumulation in upper parts of plant could be related to both the role of PGRs in the enhancement of plant resistance to stress (as toxic metals) and the increase in transpiration rate, i.e. flux of water-soluble soil components and contaminants by the regulation of stomatal opening.

  19. Topography mediates plant water stress: coupling groundwater flow and rhizosphere-xylem hydraulics

    Science.gov (United States)

    Mackay, D. S.; Tai, X.

    2016-12-01

    Explicit representation of groundwater movement and its subsidy to the unsaturated zone have long been recognized to affect land surface fluxes. But its impact on mediating plant safety during drought has not yet been evaluated, due to the oversimplified representation of the soil-plant-atmospheric continuum in current mainstream land surface models. Here we evaluated the interaction between groundwater processes and plant hydraulics by integrating a three-dimensional groundwater model - ParFlow with a physiologically sophisticated plant model - TREES. A series of simulation experiments using representative hillslope shapes during a general dry down period were carried out to explore the impacts of topography, soil properties, and plant traits - maximum hydraulic conductance (Kmax), root area (Ar), and vulnerability to cavitation on plant hydraulic stress and the potential feedbacks to soil water spatial dynamics. From an initial condition of uniform pressure, lateral redistribution dominated the first stage when soils were wet, resulting in various water table depths. As drought progressed, the tension wetted zone provided a water subsidy to the root zone, causing various rates of soil dry down at different locations. In the end, the root zone soil water remains stable and dry, with diurnal fluctuations induced by the hydraulic redistribution of plant roots. Plants, in general, had higher transpiration and lower hydraulic stress on concave hillslopes. The same plant growing on fine-textured soils had higher transpiration rate, and therefore stronger feedbacks to the water table depths, compared to coarse-textured soil. But these responses could further vary by plant traits. For locations with shallow water table, Kmax is the most important factor determining plant function. When soil is dry, plants with higher Ar and more resistant xylem sustained higher transpiration rates. Those promising performance suggests that the coupled model could be a powerful tool for

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1998-12-31

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

  1. Regeneration and growth rates of allofragments in four common stream plants

    DEFF Research Database (Denmark)

    Riis, Tenna; Madsen, Tom Vindbæk; Sennels, R. S. H.

    2009-01-01

    Colonisation by stream plants occurs to a large extent from simple stem fragments. Allofragments are stem fragments formed by mechanical breakage. We studied regeneration, colonisation, and growth rates in four common stream plants: Elodea canadensis Michx., Myriophyllum spicatum L., Potamogeton...... perfoliatus L. and Ranunculus baudotii x pseudofluitans. The objectives of this study were to determine (1) if shoots with an apical tip have higher regeneration (growth of new shoots and rhizomes from allofragments) and colonisation (root attachment in sediment) abilities and higher relative growth rates...

  2. Contrasting Rates of Molecular Evolution and Patterns of Selection among Gymnosperms and Flowering Plants

    Science.gov (United States)

    Li, Zhen; Van de Peer, Yves; Ingvarsson, Pär K.

    2017-01-01

    Abstract The majority of variation in rates of molecular evolution among seed plants remains both unexplored and unexplained. Although some attention has been given to flowering plants, reports of molecular evolutionary rates for their sister plant clade (gymnosperms) are scarce, and to our knowledge differences in molecular evolution among seed plant clades have never been tested in a phylogenetic framework. Angiosperms and gymnosperms differ in a number of features, of which contrasting reproductive biology, life spans, and population sizes are the most prominent. The highly conserved morphology of gymnosperms evidenced by similarity of extant species to fossil records and the high levels of macrosynteny at the genomic level have led scientists to believe that gymnosperms are slow-evolving plants, although some studies have offered contradictory results. Here, we used 31,968 nucleotide sites obtained from orthologous genes across a wide taxonomic sampling that includes representatives of most conifers, cycads, ginkgo, and many angiosperms with a sequenced genome. Our results suggest that angiosperms and gymnosperms differ considerably in their rates of molecular evolution per unit time, with gymnosperm rates being, on average, seven times lower than angiosperm species. Longer generation times and larger genome sizes are some of the factors explaining the slow rates of molecular evolution found in gymnosperms. In contrast to their slow rates of molecular evolution, gymnosperms possess higher substitution rate ratios than angiosperm taxa. Finally, our study suggests stronger and more efficient purifying and diversifying selection in gymnosperm than in angiosperm species, probably in relation to larger effective population sizes. PMID:28333233

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

    Science.gov (United States)

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

    2010-05-01

    Rhizosphere - one of the most important ‘hot spots' in soil - is characterized not only by accelerated turnover of microbial biomass and nutrients but also by strong intra- and inter-specific competition. Intra-specific competition occurs between individual plants of the same species, while inter-specific competition can occur both at population level (plant species-specific, microbial species-specific interactions) and at community level (plant - microbial interactions). Such plant - microbial interactions are mainly governed by competition for available N sources, since N is one of the main growth limiting nutrients in natural ecosystems. Functional structure and activity of microbial community in rhizosphere is not uniform and is dependent on quantity and quality of root exudates which are plant specific. It is still unclear how microbial growth and turnover in the rhizosphere are dependent on the features and competitive abilities of plants for N. Depending on C and N availability, acceleration and even retardation of microbial activity and carbon mineralization can be expected in the rhizosphere of plants with high competitive abilities for N. We hypothesized slower microbial growth rates in the rhizosphere of plants with smaller roots, as they usually produce less exudates compared to plants with small shoot-to-root ratio. As the first hypothesis is based solely on C availability, we also expected the greater effect of N availability on microbial growth in rhizosphere of plants with smaller root mass. These hypothesis were tested for two plant species of strawberry: Fragaria vesca L. (native species), and Duchesnea indica (Andrews) Focke (an invasive plant in central Europe) growing in intraspecific and interspecific competition. Microbial biomass and the kinetic parameters of microbial growth in the rhizosphere were estimated by dynamics of CO2 emission from the soil amended with glucose and nutrients. Specific growth rate (µ) of soil microorganisms was

  4. Heat-Rate Improvement Obtained by Retubing Power-Plant Condenser Enhanced Tubes

    Energy Technology Data Exchange (ETDEWEB)

    1994-01-21

    A utility will only retube a condenser with enhanced tubes if the incremental cost of the enhanced tubes can be offset with reduced fuel costs. The reduced fuel cost is obtained for some units because of the higher heat-transfer coefficient of enhanced tubes. They lead to improved condenser performance measured by a lower condenser pressure and therefore a more efficient power plant. However, the higher haet-transfer coefficients do not always guarantee that enhanced tubes will be more cost effective. Other issues must be considered such as the cooling-water flow reduction due to the increased pressure drop, the low-pressure turbine heat-rate variation with backpressure, and the cooling-water pump and system characteristics. These and other parameters must be considered to calculate the efficiency improvement of the power plant as commonly measured by the quantity known as the heat rate. Knowing the heat-rate improvement, the fuel cost, and the incremental increase of the enhanced tubes from the supplier, the payback time can be determined. This program calculates the heat-rate improvement that can be obtained by retubing a power plant condenser with enhanced tubes of a particular type called Korodense LPD made by Wolverine Tube, Inc. The fuel savings are easily established knowing the heat-rate improvement. All electrical utilities are potential users because a condenser is used as the heat sink for every power plant.

  5. HTRATE; Heat-Rate Improvement Obtained by Retubing Power-Plant Condenser Enhanced Tubes

    Energy Technology Data Exchange (ETDEWEB)

    Rabas, T.J. [Argonne National Lab., IL (United States)

    1990-06-01

    A utility will only retube a condenser with enhanced tubes if the incremental cost of the enhanced tubes can be offset with reduced fuel costs. The reduced fuel cost is obtained for some units because of the higher heat-transfer coefficient of enhanced tubes. They lead to improved condenser performance measured by a lower condenser pressure and therefore a more efficient power plant. However, the higher haet-transfer coefficients do not always guarantee that enhanced tubes will be more cost effective. Other issues must be considered such as the cooling-water flow reduction due to the increased pressure drop, the low-pressure turbine heat-rate variation with backpressure, and the cooling-water pump and system characteristics. These and other parameters must be considered to calculate the efficiency improvement of the power plant as commonly measured by the quantity known as the heat rate. Knowing the heat-rate improvement, the fuel cost, and the incremental increase of the enhanced tubes from the supplier, the payback time can be determined. This program calculates the heat-rate improvement that can be obtained by retubing a power plant condenser with enhanced tubes of a particular type called Korodense LPD made by Wolverine Tube, Inc. The fuel savings are easily established knowing the heat-rate improvement. All electrical utilities are potential users because a condenser is used as the heat sink for every power plant.

  6. Low-Reynolds number modelling of flows with transpiration

    Science.gov (United States)

    Hwang, C. B.; Lin, C. A.

    2000-03-01

    An improved low-Reynolds number model was adopted to predict the dynamic and thermal fields in flows with transpiration. The performance of the adopted model was first contrasted with the direct numerical simulation (DNS) data of channel flow with uniform wall injection and suction. The validity of the present model applied to flows with a high level of transpiration was further examined. To explore the model's performance in complex environments, the model was applied to simulate a transpired developing channel flow. By contrasting the predictions with DNS data and measurements, the results indicated that the present model reproduced correctly the deceleration and acceleration of the flow caused by the injection and suction from the permeable part of the wall. The turbulence structure of transpired flows was also well captured and the superior performance of the adopted model was reflected by the predicted correct level of with the maximum being located at both the injection and the suction walls. The predicted thermal field by the present model also compared favourably with the DNS data and measurements. Copyright

  7. Embolized Stems Recover Overnight in Zea mays: The Role of Soil Water, Root Pressure, and Nighttime Transpiration

    Science.gov (United States)

    Gleason, Sean M.; Wiggans, Dustin R.; Bliss, Clayton A.; Young, Jason S.; Cooper, Mitchell; Willi, Katie R.; Comas, Louise H.

    2017-01-01

    It is not currently well-understood how much xylem conductance is lost in maize plants during the day, if conductance is recovered during the night, or what soil water conditions are required for recovery to take place. To answer these questions we designed a greenhouse experiment whereby two genetically dissimilar maize genotypes were subjected to a level of water stress commonly experienced in the field (Ψxylem ∼-2 MPa). We then measured the loss of stem-specific conductivity associated with this level of stress, as well as the overnight recovery following three re-watering treatments: Ψsoil ∼ 0 MPa, Ψsoil ∼-0.40 MPa, and Ψsoil ∼-1.70 MPa. Mid-day leaf water potentials of -1.98 MPa resulted in stem-specific conductivity (KS) values that were 31.5% of maximal (i.e., 68% loss). Returning soils to field capacity (Ψsoil ∼ 0 MPa) overnight allowed for the significant recovery of KS (76% of maximal), whereas partial watering (Ψsoil ∼-0.40 MPa) resulted KS values that were 51.7% of maximal values, whereas not watering resulted in no recovery (35.4% of maximal; Ψsoil ∼-1.7 MPa). Recovery of KS was facilitated by the generation of root pressure and low rates of nighttime transpiration. PMID:28503183

  8. Wind drives nocturnal, but not diurnal, transpiration in Leucospermum conocarpodendron trees: implications for stilling on the Cape Peninsula.

    Science.gov (United States)

    Karpul, Rebecca H; West, Adam G

    2016-08-01

    Surface winds have declined in many regions of the world over the past few decades. These trends are referred to as global stilling and have recently been observed in the Western Cape Province of South Africa. The potential consequences of such changes on ecosystem function and productivity are a particular concern for the highly diverse and endemic local flora, largely associated with the fynbos biome. Yet, few studies have directly examined the impact of wind in the region. In this study, we explored the importance of wind and other drivers of plant transpiration (E) in a stand of Leucospermum conocarpodendron (L.) Buek trees on the Cape Peninsula. Wind speeds can be high in the Cape and could play an important role in influencing the rate of E Overall, the influence of wind appeared to be significantly greater at night than during the day. While daytime E responded most strongly to changes in solar radiation (R(2) = 0.79) and vapour pressure deficit (R(2) = 0.57-0.67), night-time E (En) was primarily driven by wind speed (R(2) = 0.30-0.59). These findings have important implications for stilling and other aspects of climate change. Since En was found to be a regular and significant (P < 0.00) component of total daily E (10-27%), plants may conserve water should stilling continue. Still, the extent of this could be offset by strong daytime drivers. As such, plant water consumption will most likely increase in response to a warmer and drier climate. Changes in other biophysical variables are, however, clearly important to consider in the current debate on the impact of climate change.

  9. Temperature responses of substrate carbon conversion efficiencies and growth rates of plant tissues.

    Science.gov (United States)

    Hansen, Lee D; Thomas, Nathan R; Arnholdt-Schmitt, Birgit

    2009-12-01

    Growth rates of plant tissues depend on both the respiration rate and the efficiency with which carbon is incorporated into new structural biomass. Calorespirometric measurement of respiratory heat and CO2 rates, from which both efficiency and growth rate can be calculated, is a well established method for determining the effects of rapid temperature changes on the respiratory and growth properties of plant tissues. The effect of the alternative oxidase/cytochrome oxidase activity ratio on efficiency is calculated from first principles. Data on the temperature dependence of the substrate carbon conversion efficiency are tabulated. These data show that epsilon is maximum and approximately constant through the optimum growth temperature range and decreases rapidly as temperatures approach temperature limits to growth. The width of the maximum and the slopes of decreasing epsilon at high and low temperatures vary greatly with species, cultivars and accessions.

  10. 水分胁迫对紫花苜蓿叶水势、蒸腾速率和气孔导度的影响%Impact of Water Stress on Leaf Water Potential, Transpiration Rate(Tr)and Stomatal Conductance (Gs) of Alfalfa

    Institute of Scientific and Technical Information of China (English)

    罗永忠; 成自勇

    2011-01-01

    In order to reveal the stomatal response of Alfalfa under water stress, leaf water potential, transpiration rate (Tr), stomatal conductance (Gs) of alfalfa (Medicago sativa) and their relationship under water stress are studied by adopting pot-cultivation designs. Results show that the leaf water potential, Tr and Gs of alfalfa decreased with water stress increasing. The daily change of the leaf potential, Trand Gs display a bimodal curve pattern with the same mean value. The maximum is obtained under full water supply, followed by light water stress, moderate water stress and severe water stress. The lowest leaf water potential decreases with the decreasing of soil moisture, the peak appearing time of leaf potential and Trun der moderate and severe water stress is earlier than that of full water supply and light water stress. Under moderate and severe water stress, when the water potential was -4. 68 MPa, or Tr was 3.27 g · m-2 ·h-1 , the stomata begin to close. Under full water supply and light water stress, Tr increases with the decreasing water potential, and G, increases with the increasing of Tr. The leaf water potential changes not only related with the soil moisture, but also closely related with the leaf development.%采用盆栽水分试验,研究了不同土壤水分条件下紫花苜蓿(Medicago sativa)叶水势、蒸腾速率和气孔导度的变化规律及相互关系,以期揭示其对土壤水分胁迫的气孔响应机制.结果表明:苜蓿叶水势、蒸腾速率(Tr)、气孔导度(Gs)均随水分胁迫加剧而降低,三者日变化均呈双峰曲线特征,日平均值表现为充分供水>轻度胁迫>中度胁迫>重度胁迫.最低叶水势随土壤水分降低而降低;在中度和重度胁迫下,叶水势和蒸腾速率日变化峰值出现的时间提前,当叶水势为-4.68 MPa或Tr为3.27 g·m-2·h-1时,气孔开始关闭;在充分供水和轻度胁迫下,Tr越高,叶水势越低,且G随着Tr增加而增加.叶水势的变化

  11. Effect of Salt Stress on Transpiration and Ion Distribution in Seedlings of Four Tree Species

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Transpiration rate and ion distribution of pagoda tree, walnut, velvet ash and poplar seedlings treated by NaCl solution of 0, 50, 100, 200 mmol·L-1 were studied. The results showed that there were significant differences in the response to NaCl among the four tree species. Na+ exclusion capacity of pagoda tree was the largest among the four species. The Na+ exclusion capacity of velvet ash was less than that of pagoda tree. Salt excretion capacity of velvet ash was limited. Its salt-tolerance was bigge...

  12. The transpired turbulent boundary layer in various pressure gradients and the blow-off condition

    Science.gov (United States)

    Georgiou, D. P.; Louis, J. F.

    1984-12-01

    Experimental data are reported from studies of the cooling effectiveness and conditions leading to blow-off in transpiration cooling (TC). The TC configuration used featured a sintered bronze plate in a hot blowdown wind tunnel. Cooled air was pumped through the plate and data were gathered with calorimeters downstream of a piece of sandpaper which tripped the boundary layer. Pressure taps were also used. Local pressure gradient effects were small, but local accelerations reduced the cooling effectiveness. The downstream Stanton numbers were sensitive to the upstream coolant-injection ratio. Increasing the injection rate had, at best, only a small effect on the local heat flux.

  13. Plant Science Alumni Rate Their Education Based upon Entry-Level Professional Experience.

    Science.gov (United States)

    Long, G. A.; And Others

    1992-01-01

    The relevance of plant science curriculum at Utah State University was evaluated by students graduating in 1976 through 1986 using a modified Borich Model. Oral and written communication and interpersonal skills were rated as most important. Respondents recommended including business, computer, science, oral and written communications classes, and…

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

    Science.gov (United States)

    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...

  15. The effect of differential growth rates across plants on spectral predictions of physiological parameters.

    Directory of Open Access Journals (Sweden)

    Tal Rapaport

    Full Text Available Leaves of various ages and positions in a plant's canopy can present distinct physiological, morphological and anatomical characteristics, leading to complexities in selecting a single leaf for spectral representation of an entire plant. A fortiori, as growth rates between canopies differ, spectral-based comparisons across multiple plants--often based on leaves' position but not age--becomes an even more challenging mission. This study explores the effect of differential growth rates on the reflectance variability between leaves of different canopies, and its implication on physiological predictions made by widely-used spectral indices. Two distinct irrigation treatments were applied for one month, in order to trigger the formation of different growth rates between two groups of grapevines. Throughout the experiment, the plants were physiologically and morphologically monitored, while leaves from every part of their canopies were spectrally and histologically sampled. As the control vines were constantly developing new leaves, the water deficit plants were experiencing growth inhibition, resulting in leaves of different age at similar nodal position across the treatments. This modification of the age-position correlation was characterized by a near infrared reflectance difference between younger and older leaves, which was found to be exponentially correlated (R(2 = 0.98 to the age-dependent area of intercellular air spaces within the spongy parenchyma. Overall, the foliage of the control plant became more spectrally variable, creating complications for intra- and inter-treatment leaf-based comparisons. Of the derived indices, the Structure-Insensitive Pigment Index (SIPI was found indifferent to the age-position effect, allowing the treatments to be compared at any nodal position, while a Normalized Difference Vegetation Index (NDVI-based stomatal conductance prediction was substantially affected by differential growth rates. As various

  16. Chemical signals and their interactions change transpiration processes in tomato wild-type and flacca mutant

    DEFF Research Database (Denmark)

    Prokic, Ljiljana; Wollenweber, Bernd; Stikic, Radmila

    2011-01-01

    After the exposure to soil drying treatments, plants alkalize xylem sap. Xylem sap alkalization is not one a chemical signal per se, but it also facilitates the mobilization and redistribution of the phytohormone abscisic acid (ABA). Therefore, the objective of this paper was to investigate...... the effects of chemicalsignals on the mechanism of transpiration of isolated leaves of L. esculentum Mill. cv. Ailsa Craig (WT) and mutant flacca. In bioassays, exogenic activity of different ABA concentrations and pH were tested in both genotype of tomato in order to stimulate chemical signals occurring...... existed in flacca, when compared pH changed media with unchanged. Mutaul effects 10nM ABA and different pH on transpiration kinetics resulted in short and rapid stomatal closure. Similar interaction was obtained inflacca as slow phases of stomatal closure, but with a higher concentration of ABA (10m...

  17. The transpiration of water at negative pressures in a synthetic tree.

    Science.gov (United States)

    Wheeler, Tobias D; Stroock, Abraham D

    2008-09-11

    Plant scientists believe that transpiration-the motion of water from the soil, through a vascular plant, and into the air-occurs by a passive, wicking mechanism. This mechanism is described by the cohesion-tension theory: loss of water by evaporation reduces the pressure of the liquid water within the leaf relative to atmospheric pressure; this reduced pressure pulls liquid water out of the soil and up the xylem to maintain hydration. Strikingly, the absolute pressure of the water within the xylem is often negative, such that the liquid is under tension and is thermodynamically metastable with respect to the vapour phase. Qualitatively, this mechanism is the same as that which drives fluid through the synthetic wicks that are key elements in technologies for heat transfer, fuel cells and portable chemical systems. Quantitatively, the differences in pressure generated in plants to drive flow can be more than a hundredfold larger than those generated in synthetic wicks. Here we present the design and operation of a microfluidic system formed in a synthetic hydrogel. This synthetic 'tree' captures the main attributes of transpiration in plants: transduction of subsaturation in the vapour phase of water into negative pressures in the liquid phase, stabilization and flow of liquid water at large negative pressures (-1.0 MPa or lower), continuous heat transfer with the evaporation of liquid water at negative pressure, and continuous extraction of liquid water from subsaturated sources. This development opens the opportunity for technological uses of water under tension and for new experimental studies of the liquid state of water.

  18. Estimation of leak rate through circumferential cracks in pipes in nuclear power plants

    Directory of Open Access Journals (Sweden)

    Jai Hak Park

    2015-04-01

    Full Text Available The leak before break (LBB concept is widely used in designing pipe lines in nuclear power plants. According to the concept, the amount of leaking liquid from a pipe should be more than the minimum detectable leak rate of a leak detection system before catastrophic failure occurs. Therefore, accurate estimation of the leak rate is important to evaluate the validity of the LBB concept in pipe line design. In this paper, a program was developed to estimate the leak rate through circumferential cracks in pipes in nuclear power plants using the Henry–Fauske flow model and modified Henry–Fauske flow model. By using the developed program, the leak rate was calculated for a circumferential crack in a sample pipe, and the effect of the flow model on the leak rate was examined. Treating the crack morphology parameters as random variables, the statistical behavior of the leak rate was also examined. As a result, it was found that the crack morphology parameters have a strong effect on the leak rate and the statistical behavior of the leak rate can be simulated using normally distributed crack morphology parameters.

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

    Science.gov (United States)

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

    2011-01-01

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

  20. Restoration and management for plant diversity enhances the rate of belowground ecosystem recovery.

    Science.gov (United States)

    Klopf, Ryan P; Baer, Sara G; Bach, Elizabeth M; Six, Johan

    2017-03-01

    The positive relationship between plant diversity and ecosystem functioning has been criticized for its applicability at large scales and in less controlled environments that are relevant to land management. To inform this gap between ecological theory and application, we compared recovery rates of belowground properties using two chronosequences consisting of continuously cultivated and independently restored fields with contrasting diversity management strategies: grasslands restored with high plant richness and managed for diversity with frequent burning (n = 20) and grasslands restored with fewer species that were infrequently burned (n = 15). Restoration and management for plant diversity resulted in 250% higher plant richness. Greater recovery of roots and more predictable recovery of the active microbial biomass across the high diversity management strategy chronosequence corresponded with faster recovery of soil structure. The high diversity grasslands also had greater nutrient conservation indicated by lower available inorganic nitrogen. Thus, mesic grasslands restored with more species and managed for high plant diversity with frequent burning enhances the rate of belowground ecosystem recovery from long-term disturbance at a scale relevant to conservation practices on the landscape.

  1. Comparison of root water uptake modules using either the surface energy balance or potential transpiration

    Science.gov (United States)

    Braud, Isabelle; Varado, Noémie; Olioso, Albert

    2005-01-01

    Numerical models simulating changes in soil water content with time rely on accurate estimation of root water uptake. This paper considers two root water uptake modules that have a compensation mechanism allowing for increased root uptake under conditions of water stress. These modules, proposed by Lai and Katul and Li et al. [Adv. Water Resour. 23 (2000) 427 and J. Hydrol. 252 (2001) 189] use potential transpiration weighted, for each soil layer, by a water stress and a compensation function in order to estimate actual transpiration. The first objective of the paper was to assess the accuracy of the proposed root extraction modules against two existing data sets, acquired under dry conditions for a winter wheat and a soybean crop. In order to perform a fair comparison, both modules were included as possible root water extraction modules within the Simple Soil Plant Atmosphere Transfer (SiSPAT) model. In this first set of simulations, actual transpiration was calculated using the solution of the surface energy budget as implemented in the SiSPAT model. Under such conditions, both root extraction modules were able to reproduce accurately the time evolution of soil moisture at various depths, soil water storage and daily evaporation. Results were generally improved when we activated the compensation mechanisms. However, we showed that Lai and Katul [Adv. Water Resour. 23 (2000) 427] module was sensitive to soil hydraulic properties through its water stress function, whereas the Li et al. [J. Hydrol. 252 (2001) 189] module was not very sensitive to the specification of its parameter. The latter module is therefore recommended for inclusion into a larger scale hydrological model, due to its robustness. When water balance models are run at larger scales or on areas with scarce data, actual transpiration is often calculated using models based on potential transpiration without solving the surface energy balance. The second objective of the paper was to assess the loss of

  2. Heat rate curve approximation for power plants without data measuring devices

    Energy Technology Data Exchange (ETDEWEB)

    Poullikkas, Andreas [Electricity Authority of Cyprus, P.O. Box 24506, 1399 Nicosia (CY

    2012-07-01

    In this work, a numerical method, based on the one-dimensional finite difference technique, is proposed for the approximation of the heat rate curve, which can be applied for power plants in which no data acquisition is available. Unlike other methods in which three or more data points are required for the approximation of the heat rate curve, the proposed method can be applied when the heat rate curve data is available only at the maximum and minimum operating capacities of the power plant. The method is applied on a given power system, in which we calculate the electricity cost using the CAPSE (computer aided power economics) algorithm. Comparisons are made when the least squares method is used. The results indicate that the proposed method give accurate results.

  3. Heat rate curve approximation for power plants without data measuring devices

    Directory of Open Access Journals (Sweden)

    Andreas Poullikkas

    2012-01-01

    Full Text Available In this work, a numerical method, based on the one-dimensional finite difference technique, is proposed for the approximation of the heat rate curve, which can be applied for power plants in which no data acquisition is available. Unlike other methods in which three or more data points are required for the approximation of the heat rate curve, the proposed method can be applied when the heat rate curve data is available only at the maximum and minimum operating capacities of the power plant. The method is applied on a given power system, in which we calculate the electricity cost using the CAPSE (computer aided power economics algorithm. Comparisons are made when the least squares method is used. The results indicate that the proposed method give accurate results.

  4. Initiating Event Rates at U.S. Nuclear Power Plants. 1988 - 2013

    Energy Technology Data Exchange (ETDEWEB)

    Schroeder, John A.; Bower, Gordon R.

    2014-02-01

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

  5. Carbohydrates Concentration in leaves of potato plants affected by nitrogen fertilization rates

    Directory of Open Access Journals (Sweden)

    Heder Braun

    2016-04-01

    Full Text Available ABSTRACT At poor conditions of nitrogen (N in the soil, potato plants may accumulate starch in leaves and be indicative of N nutritional stress. The objective of this work was to determine the effects of N rates (0, 50, 100, 200 and 300 kg ha-1 of N on the concentrations of carbohydrates (total soluble sugars-TSS, reducing sugars-RS, non-reducing sugars-NRS and starch in the fourth leaf (FL of two potato cultivars (Asterix and Atlantic and their critical levels (CL associated to the N fertilization rate necessary to obtain the maximum physical (MPE and economic (MEE efficiency of tubers. A randomized block design with four replications was used in both experiments. On day 21 after plant emergence, four FL were collected from four plants. Potatoes plants fertilized with low rates of N accumulated less TSS in leaves than those properly fertilized. The opposite occurred with content of starch. The cultivars showed similar responses to five doses of N in relation to contents of starch and TSS. However, the response to the increase in doses of N for RS, NRS and Starch/NRS is cultivar-specific. The correlations between contents of RS, NRS and Starch/NRS with the starch and TSS were dependent on the potato cultivar.

  6. Legume presence reduces the decomposition rate of non-legume roots, role of plant traits?

    Science.gov (United States)

    De Deyn, Gerlinde B.; Saar, Sirgi; Barel, Janna; Semchenko, Marina

    2016-04-01

    Plant litter traits are known to play an important role in the rate of litter decomposition and mineralization, both for aboveground and belowground litter. However also the biotic and abiotic environment in which the litter decomposes plays a significant role in the rate of decomposition. The presence of living plants may accelerate litter decomposition rates via a priming effects. The size of this effect is expected to be related to the traits of the litter. In this study we focus on root litter, given that roots and their link to ecosystem processes have received relatively little attention in trait-based research. To test the effect of a growing legume plant on root decomposition and the role of root traits in this we used dead roots of 7 different grassland species (comprising grasses, a forb and legumes), determined their C, N, P content and quantified litter mass loss after eight weeks of incubation in soil with and without white clover. We expected faster root decomposition with white clover, especially for root litter with low N content. In contrast we found slower decomposition of grass and forb roots which were poor in N (negative priming) in presence of white clover, while decomposition rates of legume roots were not affected by the presence of white clover. Overall we found that root decomposition can be slowed down in the presence of a living plant and that this effect depends on the traits of the decomposing roots, with a pronounced reduction in root litter poor in N and P, but not in the relatively nutrient-rich legume root litters. The negative priming effect of legume plants on non-legume litter decomposition may have resulted from preferential substrate utilisation by soil microbes.

  7. Absorbed dose rate in air in metropolitan Tokyo before the Fukushima Daiichi Nuclear Power Plant accident.

    Science.gov (United States)

    Inoue, K; Hosoda, M; Fukushi, M; Furukawa, M; Tokonami, S

    2015-11-01

    The monitoring of absorbed dose rate in air has been carried out continually at various locations in metropolitan Tokyo after the accident of the Fukushima Daiichi Nuclear Power Plant. While the data obtained before the accident are needed to more accurately assess the effects of radionuclide contamination from the accident, detailed data for metropolitan Tokyo obtained before the accident have not been reported. A car-borne survey of the absorbed dose rate in air in metropolitan Tokyo was carried out during August to September 2003. The average absorbed dose rate in air in metropolitan Tokyo was 49±6 nGy h(-1). The absorbed dose rate in air in western Tokyo was higher compared with that in central Tokyo. Here, if the absorbed dose rate indoors in Tokyo is equivalent to that outdoors, the annual effective dose would be calculated as 0.32 mSv y(-1).

  8. Relation between Silver Nanoparticle Formation Rate and Antioxidant Capacity of Aqueous Plant Leaf Extracts

    Directory of Open Access Journals (Sweden)

    Azat Akbal

    2016-01-01

    Full Text Available Correlation between the antioxidant capacity and silver nanoparticle formation rates of pomegranate (Punica granatum, quince (Cydonia oblonga, chestnut (Castanea sativa, fig (Ficus carica, walnut (Juglans cinerea, black mulberry (Morus nigra, and white mulberry (Morus alba leaf extracts is investigated at a fixed illumination. Silver nanoparticles formed in all plant leaf extracts possess round shapes with average particle size of 15 to 25 nm, whereas corresponding surface plasmon resonance peak wavelengths vary between 422 nm and 451 nm. Cupric reducing antioxidant capacity technique is used as a reference method to determine total antioxidant capacity of the plant leaf extracts. Integrated absorbance over the plasmon resonance peaks exhibits better linear relation with antioxidant capacities of various plant leaf extracts compared to peak absorbance values, with correlation coefficient values of 0.9333 and 0.7221, respectively.

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

    DEFF Research Database (Denmark)

    Riis, Tenna

    2008-01-01

    Plant dispersal and colonisation, including rates of dispersal, retention, colonisation and survival of dispersed propagules (shoots and seeds), were studied in a 300-m stream reach in a macrophyte-rich lowland stream during one growing season. Relationships between colonisation processes...... and seeds, due in part to low retention success (1% of the dispersed shoots per 100-m reach) and to unsuccessful colonisation of retained shoots (3.4% of retained shoots colonised). The number of drifting shoots and seeds per day during the growing season were 650-6,950 and 2,970-62,780, respectively...... and simple flow parameters were tested. Each fortnight during a growing season, the number of dispersed plant propagules and the number of new and lost plant colonisations since the last sampling day were recorded. The retention of dispersing shoots was tested on two occasions during the growing season...

  10. Radiation dose rate map interpolation in nuclear plants using neural networks and virtual reality techniques

    Energy Technology Data Exchange (ETDEWEB)

    Mol, Antonio Carlos A., E-mail: mol@ien.gov.br [Comissao Nacional de Energia Nuclear, Instituto de Engenharia Nuclear Rua Helio de Almeida, 75, Ilha do Fundao, P.O. Box 68550, 21941-906 Rio de Janeiro, RJ (Brazil); Instituto Nacional de Ciencia e Tecnologia de Reatores Nucleares Inovadores/CNPq (Brazil); Pereira, Claudio Marcio N.A., E-mail: cmnap@ien.gov.br [Comissao Nacional de Energia Nuclear, Instituto de Engenharia Nuclear Rua Helio de Almeida, 75, Ilha do Fundao, P.O. Box 68550, 21941-906 Rio de Janeiro, RJ (Brazil); Instituto Nacional de Ciencia e Tecnologia de Reatores Nucleares Inovadores/CNPq (Brazil); Freitas, Victor Goncalves G. [Universidade Federal do Rio de Janeiro, Programa de Engenharia Nuclear, Rio de Janeiro, RJ (Brazil); Jorge, Carlos Alexandre F., E-mail: calexandre@ien.gov.br [Comissao Nacional de Energia Nuclear, Instituto de Engenharia Nuclear Rua Helio de Almeida, 75, Ilha do Fundao, P.O. Box 68550, 21941-906 Rio de Janeiro, RJ (Brazil)

    2011-02-15

    This paper reports the most recent development results of a simulation tool for assessment of radiation dose exposition by nuclear plant's personnel, using artificial intelligence and virtual reality technologies. The main purpose of this tool is to support training of nuclear plants' personnel, to optimize working tasks for minimisation of received dose. A finer grid of measurement points was considered within the nuclear plant's room, for different power operating conditions. Further, an intelligent system was developed, based on neural networks, to interpolate dose rate values among measured points. The intelligent dose prediction system is thus able to improve the simulation of dose received by personnel. This work describes the improvements implemented in this simulation tool.

  11. Water-use efficiency and transpiration across European forests during the Anthropocene

    Science.gov (United States)

    Frank, D. C.; Poulter, B.; Saurer, M.; Esper, J.; Huntingford, C.; Helle, G.; Treydte, K.; Zimmermann, N. E.; Schleser, G. H.; Ahlström, A.; Ciais, P.; Friedlingstein, P.; Levis, S.; Lomas, M.; Sitch, S.; Viovy, N.; Andreu-Hayles, L.; Bednarz, Z.; Berninger, F.; Boettger, T.; D`Alessandro, C. M.; Daux, V.; Filot, M.; Grabner, M.; Gutierrez, E.; Haupt, M.; Hilasvuori, E.; Jungner, H.; Kalela-Brundin, M.; Krapiec, M.; Leuenberger, M.; Loader, N. J.; Marah, H.; Masson-Delmotte, V.; Pazdur, A.; Pawelczyk, S.; Pierre, M.; Planells, O.; Pukiene, R.; Reynolds-Henne, C. E.; Rinne, K. T.; Saracino, A.; Sonninen, E.; Stievenard, M.; Switsur, V. R.; Szczepanek, M.; Szychowska-Krapiec, E.; Todaro, L.; Waterhouse, J. S.; Weigl, M.

    2015-06-01

    The Earth’s carbon and hydrologic cycles are intimately coupled by gas exchange through plant stomata. However, uncertainties in the magnitude and consequences of the physiological responses of plants to elevated CO2 in natural environments hinders modelling of terrestrial water cycling and carbon storage. Here we use annually resolved long-term δ13C tree-ring measurements across a European forest network to reconstruct the physiologically driven response of intercellular CO2 (Ci) caused by atmospheric CO2 (Ca) trends. When removing meteorological signals from the δ13C measurements, we find that trees across Europe regulated gas exchange so that for one ppmv atmospheric CO2 increase, Ci increased by ~0.76 ppmv, most consistent with moderate control towards a constant Ci/Ca ratio. This response corresponds to twentieth-century intrinsic water-use efficiency (iWUE) increases of 14 +/- 10 and 22 +/- 6% at broadleaf and coniferous sites, respectively. An ensemble of process-based global vegetation models shows similar CO2 effects on iWUE trends. Yet, when operating these models with climate drivers reintroduced, despite decreased stomatal opening, 5% increases in European forest transpiration are calculated over the twentieth century. This counterintuitive result arises from lengthened growing seasons, enhanced evaporative demand in a warming climate, and increased leaf area, which together oppose effects of CO2-induced stomatal closure. Our study questions changes to the hydrological cycle, such as reductions in transpiration and air humidity, hypothesized to result from plant responses to anthropogenic emissions.

  12. Sensitivity of simulated terrestrial carbon assimilation and canopy transpiration to different stomatal conductance and carbon assimilation schemes

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Haishan [Nanjing University of Information Science and Technology, Key Laboratory of Meteorological Disaster of Ministry of Education, Nanjing (China); Georgia Institute of Technology, School of Earth and Atmospheric Sciences, Atlanta, GA (United States); Dickinson, Robert E. [Georgia Institute of Technology, School of Earth and Atmospheric Sciences, Atlanta, GA (United States); The University of Texas at Austin, Department of Geological Sciences, Austin, TX (United States); Dai, Yongjiu [Beijing Normal University, State Key Laboratory of Earth Surface Processes and Resource Ecology, School of Global Change and Earth System Science, Beijing (China); Zhou, Liming [Georgia Institute of Technology, School of Earth and Atmospheric Sciences, Atlanta, GA (United States)

    2011-03-15

    Accurate simulations of terrestrial carbon assimilation and canopy transpiration are needed for both climate modeling and vegetation dynamics. Coupled stomatal conductance and carbon assimilation (A - g{sub s}) models have been widely used as part of land surface parameterizations in climate models to describe the biogeophysical and biogeochemical roles of terrestrial vegetation. Differences in various A - g{sub s} schemes produce substantial differences in the estimation of carbon assimilation and canopy transpiration, as well as in other land-atmosphere fluxes. The terrestrial carbon assimilation and canopy transpiration simulated by two different representative A - g{sub s} schemes, a simple A-g{sub s} scheme adopted from the treatments of the NCAR model (Scheme I) and a two-big-leaf A - g{sub s} scheme newly developed by Dai et al. (J Clim 17:2281-2299, 2004) (Scheme II), are compared via some sensitivity experiments to investigate impacts of different A - g{sub s} schemes on the simulations. Major differences are found in the estimate of canopy carbon assimilation rate, canopy conductance and canopy transpiration between the two schemes, primarily due to differences in (a) functional forms used to estimate parameters for carbon assimilation sub-models, (b) co-limitation methods used to estimate carbon assimilation rate from the three limiting rates, and (c) leaf-to-canopy scaling schemes. On the whole, the differences in the scaling approach are the largest contributor to the simulation discrepancies, but the different methods of co-limitation of assimilation rate also impact the results. Except for a few biomes, the residual effects caused by the different parameter estimations in assimilation sub-models are relatively small. It is also noted that the two-leaf temperature scheme produces distinctly different sunlit and shaded leaf temperatures but has negligible impacts on the simulation of the carbon assimilation. (orig.)

  13. GAS EXCHANGE IN YOUNG PLANTS OF Tabebuia aurea(Bignoniaceae Juss. SUBJECTED TO FLOODING STRESS1

    Directory of Open Access Journals (Sweden)

    Ademir Kleber Morbeck Oliveira

    2016-02-01

    Full Text Available ABSTRACT The Paratudo (Tabebuia aurea is a species occurring in the Pantanal of Miranda, Mato Grosso do Sul, Brazil, an area characterized by seasonal flooding. To evaluate the tolerance of this plant to flooding, plants aged four months were grown in flooded soil and in non-flooded soil (control group. Stomatal conductance, transpiration and CO2 assimilation were measured during the stress (48 days and recovery (11 days period, totalling 59 days. The values of stomatal conductance of the control group and stressed plants at the beginning of the flooded were 0.33 mol m-2s-1 and reached 0.02 mol m-2 s-1 (46th day at the end of this event. For the transpiration parameter, the initial rate was 3.1 mol m s-1, and the final rate reached 0.2 or 0.3 mol m-2 s-1 (47/48 th day. The initial photosynthesis rate was 8.9 mmol m-2s-1 and oscillated after the sixth day, and the rate reached zero on the 48th day. When the photosynthesis rate reached zero, the potted plants were dried, and the rate was analyzed (11th day. The following values were obtained for dried plants: stomatal conductance = 0.26 mol m-2 s-1, transpiration rate = 2.5 mol m-2 s-1 and photosynthesis rate = 7.8 mmol m-2 s-1. Flooded soil reduced photosynthesis and stomatal conductance, leading to the hypertrophy of the lenticels. These parameters recovered and after this period, and plants exhibited tolerance to flooding stress by reducing their physiological activities.

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

    OpenAIRE

    Stemke, JA; Santiago, LS

    2011-01-01

    The proportional light absorptance by photosynthetic tissue (α) is used with chlorophyll (Chl) fluorescence methods to calculate electron transport rate (ETR). Although a value of α of 0.84 is often used as a standard for calculating ETR, many succulent plant species and species with crassulacean acid metabolism (CAM) have photosynthetic tissues that vary greatly in color or are highly reflective, and could have values of α that differ from 0.84, thus affecting the calculation of ETR. We meas...

  15. Speed versus endurance tradeoff in plants: Leaves with higher photosynthetic rates show stronger seasonal declines

    Science.gov (United States)

    Zhang, Yong-Jiang; Sack, Lawren; Cao, Kun-Fang; Wei, Xue-Mei; Li, Nan

    2017-01-01

    We tested for a tradeoff across species between plant maximum photosynthetic rate and the ability to maintain photosynthesis under adverse conditions in the unfavorable season. Such a trade-off would be consistent with the observed trade-off between maximum speed and endurance in athletes and some animals that has been explained by cost-benefit theory. This trend would have importance for the general understanding of leaf design, and would simplify models of annual leaf carbon relations. We tested for such a trade-off using a database analysis across vascular plants and using an experimental approach for 29 cycad species, representing an ancient plant lineage with diversified evergreen leaves. In both tests, a higher photosynthetic rate per mass or per area in the favorable season was associated with a stronger absolute or percent decline in the unfavorable season. We resolved a possible mechanism based on biomechanics and nitrogen allocation; cycads with high leaf toughness (leaf mass per area) and higher investment in leaf construction than in physiological function (C/N ratio) tended to have lower warm season photosynthesis but less depression in the cool season. We propose that this trade-off, consistent with cost-benefit theory, represents a significant physio-phenological constraint on the diversity and seasonal dynamics of photosynthetic rate. PMID:28186201

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

    Science.gov (United States)

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

    2013-10-20

    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 0.2 MPa, and increased with increasing total pressure from 0.3 to 0.5 MPa at a low humidity. The rate of net photosynthesis decreased linearly with increasing total pressure under a constant partial pressure of CO2 at 40 Pa. 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.

  17. Comparative genomics reveals convergent rates of evolution in ant-plant mutualisms.

    Science.gov (United States)

    Rubin, Benjamin E R; Moreau, Corrie S

    2016-08-25

    Symbiosis-the close and often long-term interaction of species-is predicted to drive genome evolution in a variety of ways. For example, parasitic interactions have been shown to increase rates of molecular evolution, a trend generally attributed to the Red Queen Hypothesis. However, it is much less clear how mutualisms impact the genome, as both increased and reduced rates of change have been predicted. Here we sequence the genomes of seven species of ants, three that have convergently evolved obligate plant-ant mutualism and four closely related species of non-mutualists. Comparing these sequences, we investigate how genome evolution is shaped by mutualistic behaviour. We find that rates of molecular evolution are higher in the mutualists genome wide, a characteristic apparently not the result of demography. Our results suggest that the intimate relationships of obligate mutualists may lead to selective pressures similar to those seen in parasites, thereby increasing rates of evolution.

  18. Effect of planting dates and nitrogen rates on yield and yield components of black cumin (Nigella Sativa L.

    Directory of Open Access Journals (Sweden)

    hamed javadi

    2009-06-01

    Full Text Available In order to study the effect of planting dates and nitrogen rates on yield and yield components of black cumin (Nigella sativa L. a field experiment was conducted in spring 2006 in the Azad University of Birjand. The experiment was done as split plot based on compeletely randomized block design with 3 replications. Four planting dates (21 March, 4, 21 April, 5 May were used as main plot and 3 levels of nitrogen (40, 80 and 120 kg/ha were as sub plot. The results showed that the planting dates effect was significant on traits such as plant height, number of main branches, number of follicles per plant, biological yield and grain yield. As, maximum plant height, number of follicles per plant and biological yield were observed in first planting date and maximum number of main branches and grain yield were observed in first and second planting dates. Planting dates had no significant effects on number of follicles in main branches, number of seed per follicles, weight of 1000 seeds and harvest index. Nitrogen rates and interaction between planting dates and nitrogen rates had no significant effect on the traits. According to the results of this experiment 40 kg/ha nitrogen is enough for black cumin. Also, planting dates in 21 March and 4 April were recognised better because of high yield production.

  19. Increasing nitrogen rates in rice and its effect on plant nutrient composition and nitrogen apparent recovery

    Directory of Open Access Journals (Sweden)

    Juan Hirzel

    2013-12-01

    Full Text Available Rice (Oryza sativa L. is one of the essential foods of the human diet; advances in agronomic crop management can improve productivity and profitability as well as reduce adverse environmental impacts. Nitrogen rates in Chile are generally based on crop yield without considering other agronomic factors. The objective of this experiment was to determine the effect of increasing N rates on plant nutrient composition and N apparent recovery in rice cultivated in five different locations in Chile. The five sites located in central Chile belong to one of the following soil orders: Inceptisol, Alfisol, and Vertisol; they were cropped in field conditions with 'Zafiro-INIA' rice fertilized with 0, 80, and 160 kg N ha-1. Whole-plant total DM, macronutrient composition, and N apparent recovery efficiency (NARE were determined at grain harvest. Results indicate that all evaluated parameters, with the exception of K concentration, were affected by the soil used. Nitrogen rates only affected total DM production and P, K, and Mg concentrations in plants. Phosphorus and K response decreased when N was added to some soils, which is associated with its chemical properties. Magnesium concentration exhibited an erratic effect, but it was not affected by the N rate in most soils. Nitrogen apparent recovery efficiency was not affected by the N rate and accounted for approximately 49% and 41% for 80 and 160 kg N ha-1, respectively. Macronutrient composition was 5.1-7.7 g N, 1.3-1.8 g P, 5.4-10.8 g K, 1.68-2.57 g Ca, and 0.81-1.45 g Mg kg-1 of total DM.

  20. Modelling of root ABA synthesis, stomatal conductance, transpiration and potato production under water saving irrigation regimes

    DEFF Research Database (Denmark)

    Plauborg, Finn; Abrahamsen, Per; Gjettermann, Birgitte

    2010-01-01

    a central role in reducing crop transpiration. This paper presented a mechanistic model (Daisy) developed based on data obtained in the SAFIR project on measured leaf gas exchange and soil water dynamics in irrigated potato crops grown in a semi-field environment subjected to different irrigation regimes...... Daisy model is capable of simulating the mechanisms underlying the water saving effects of the partial root-zone drying (PRD) irrigation as compared with the conventional full irrigation (FI). However the simulated effect on both crop yield and water use in this particular experiment was negligible......Application of water saving irrigation strategies in agriculture has become increasingly important. Both modelling and experimental work are needed to gain more insights into the biological and physical mechanisms in the soil-plant system, which regulates water flow in the system and plays...

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

    Science.gov (United States)

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

    2014-11-01

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

  2. Evapo-transpiration, role of aerosol radiative forcing: a study over a dense canopy

    Science.gov (United States)

    Bhanage, VInayak; Latha, R.; Murthy, B. S.

    2016-05-01

    Current study uses Satellite and Reanalysis data to quantify the effect of aerosol on ET at various space and time scales. All the data are obtained for the period June 2008 to May 2009 over Dibrugarh district, Assam, Indi a where NDVI has limited change of through the year. Monthly Evapo-Transpiration (ET, cumulative), Normalized Difference Vegetation Index (NDVI) and Aerosol Optical Depth (AOD) are retrieved from satellite images of Terra-MODIS. The AOD data are evaluated against in-situ observations. Maximum values of AOD are observed in the pre-monsoon season while minimum AOD values are perceived in October and November. Aerosol Radiative Forcing (ARF) is calculated by using the MERRA data sets of `clean-clear radiation' and `clear-radiation' at surface over the study area. Maximum aerosol radiative forcing is observed during the pre-monsoon season; this is in tune with ground observations. Strong positive correlation (r=0.75) between ET and NDVI is observed and it is found that the dense vegetative surfaces exhibit higher rate of evapo-transpiration. A strong positive correlation (r= -0.85) between ARF at surface and AOD is observed with radiative forcing efficiency of 35 W/m2. A statistical regression equation of ET a s a function of NDVI and AOD i.e. ET = 0.25 + (-84.27) * AOD + (131.51) * NDVI, is obtained that shows a correlation of 0.824.

  3. Revisiting the Lie-group symmetry method for turbulent channel flow with wall transpiration

    CERN Document Server

    Khujadze, George

    2016-01-01

    The Lie-group-based symmetry analysis, as first proposed in Avsarkisov et al. (2014) and then later modified in Oberlack et al. (2015), to generate invariant solutions in order to predict the scaling behavior of a channel flow with uniform wall transpiration, is revisited. By focusing first on the results obtained in Avsarkisov et al. (2014), we failed to reproduce two key results: (i) For different transpiration rates at a constant Reynolds number, the mean velocity profiles (in deficit form) do not universally collapse onto a single curve as claimed. (ii) The universally proposed logarithmic scaling law in the center of the channel does not match the direct numerical simulation (DNS) data for the presented parameter values. In fact, no universal scaling behavior in the center of the channel can be detected from their DNS data, as it is misleadingly claimed in Avsarkisov et al. (2014). Moreover, we will demonstrate that the assumption of a Reynolds-number independent symmetry analysis is not justified for th...

  4. A real-time phenotyping framework using machine learning for plant stress severity rating in soybean.

    Science.gov (United States)

    Naik, Hsiang Sing; Zhang, Jiaoping; Lofquist, Alec; Assefa, Teshale; Sarkar, Soumik; Ackerman, David; Singh, Arti; Singh, Asheesh K; Ganapathysubramanian, Baskar

    2017-01-01

    Phenotyping is a critical component of plant research. Accurate and precise trait collection, when integrated with genetic tools, can greatly accelerate the rate of genetic gain in crop improvement. However, efficient and automatic phenotyping of traits across large populations is a challenge; which is further exacerbated by the necessity of sampling multiple environments and growing replicated trials. A promising approach is to leverage current advances in imaging technology, data analytics and machine learning to enable automated and fast phenotyping and subsequent decision support. In this context, the workflow for phenotyping (image capture → data storage and curation → trait extraction → machine learning/classification → models/apps for decision support) has to be carefully designed and efficiently executed to minimize resource usage and maximize utility. We illustrate such an end-to-end phenotyping workflow for the case of plant stress severity phenotyping in soybean, with a specific focus on the rapid and automatic assessment of iron deficiency chlorosis (IDC) severity on thousands of field plots. We showcase this analytics framework by extracting IDC features from a set of ~4500 unique canopies representing a diverse germplasm base that have different levels of IDC, and subsequently training a variety of classification models to predict plant stress severity. The best classifier is then deployed as a smartphone app for rapid and real time severity rating in the field. We investigated 10 different classification approaches, with the best classifier being a hierarchical classifier with a mean per-class accuracy of ~96%. We construct a phenotypically meaningful 'population canopy graph', connecting the automatically extracted canopy trait features with plant stress severity rating. We incorporated this image capture → image processing → classification workflow into a smartphone app that enables automated real-time evaluation of IDC

  5. Effects of Plant Density and Nitrogen Application Rate on Grain Yield and Nitrogen Uptake of Super Hybrid Rice

    Institute of Scientific and Technical Information of China (English)

    LIN Xian-qing; ZHU De-feng; CHEN Hui-zhe; ZHANG Yu-ping

    2009-01-01

    The nitrogen uptake, yield and its components for two super-high-yielding hybrid rice combinations, Guodao 6 and Eryou 7954 were investigated under different plant densities (15, 18, and 21 plants/m2) and different nitrogen application rates (120, 150, 180, and 210 kg/hm2). The experiment was conducted on loam soil during 2004-2006 at the experimental farm of the China National Rice Research Institute in Hangzhou, China. In these years, the two hybrid rice clearly showed higher yield at a plant density of 15 plants/m2 with a nitrogen application rate of 180 kg/hm2. Guodao 6 produced an average grain yield of 10 215.6 kg/hm2 across the three years, while the yield of Eryou 7954 was 9 633.0 kg/hm2. With fewer plants per unit-area and larger plants in the plots, the two hybrid rice produced more panicles per plant in three years. The highest nitrogen uptake of the two hybrid rice was at a plant density of 15 plants/m2 with a nitrogen application rate of 180 kg/hm2. Further increasing nitrogen application rate was not advantageous for nitrogen uptake in super-high-yielding rice under the same plant density.

  6. Use of virtual reality to estimate radiation dose rates in nuclear plants

    Energy Technology Data Exchange (ETDEWEB)

    Augusto, Silas C.; Mol, Antonio C.A.; Jorge, Carlos A.F. [Instituto de Engenharia Nuclear (IEN/CNEN-RJ), Rio de Janeiro, RJ (Brazil)]. E-mail: silas@ien.gov.br; Couto, Pedro M. [Faculdade Paraiso, Sao Goncalo, RJ (Brazil). Sistemas de Informacao]. E-mail: pedro98@gmail.com; Cunha, Gerson G.; Landau, Luis [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia (COPPE). Lab. de Metodos Computacionais em Engenharia (LAMCE)]. E-mail: gerson@lamce.ufrj.br

    2007-07-01

    Operators in nuclear plants receive radiation doses during several different operation procedures. A training program capable of simulating these operation scenarios will be useful in several ways, helping the planning of operational procedures so as to reduce the doses received by workers, and to minimize operations' times. It can provide safe virtual operation training, visualization of radiation dose rates, and estimation of doses received by workers. Thus, a virtual reality application, a free game engine, has been adapted to achieve the goals of this project. Simulation results for Argonauta research reactor of Instituto de Engenharia Nuclear are shown in this paper. A database of dose rate measurements, previously performed by the radiological protection service, has been used to display the dose rate distribution in the region of interest. The application enables the user to walk in the virtual scenario, displaying at all times the dose accumulated by the avatar. (author)

  7. Wheat cultivars selected for high Fv/Fm under heat stress maintain high photosynthesis, total chlorophyll, stomatal conductance, transpiration and dry matter

    DEFF Research Database (Denmark)

    Sharma, Dew Kumari; Andersen, Sven Bode; Ottosen, Carl-Otto

    2015-01-01

    ) than the low group, accompanied by higher stomatal conductance (gs), transpiration rate (E) and evaporative cooling of the leaf (ΔT). The difference in PN between the groups was not caused by differences in PSII capacity or gs as the variation in Fv/Fm and intracellular CO2 (Ci) was non...

  8. Influence of Seeding Rate on Weed Density in Soybean Planting System for Southeastern Coastal Plains

    Directory of Open Access Journals (Sweden)

    Pawel Wiatrak

    2011-01-01

    Full Text Available Problem statement: Increasing seeding rates may help decrease weed pressure in soybean [Glycine max (L. Merr.] wide row spacing. Approach: The objective of this study was to evaluate the influence of five glyphosate-resistant soybean Maturity Groups (MG (IV, V, VI, VII and VIII and six seeding rates (68,000,136,000, 204,000, 272,000, 340,000 and 408,000 seeds ha-1 on weed density under dryland conditions on the Southeastern coastal plain in 2007-2009. Results: Weed decrease with increasing seeding rate varied over years. Weed density was generally lower at higher seeding rates for most MG soybeans at 30 and 60 DAP, except MG IV and VIII at 30 DAP in 2007 and MG VI at 30 DAP in 2008. At 60 DAP, soybean leaf area index (LAI and normalized difference vegetation index (NDVI were greater with lower weed density. Conclusion: Additionally, negative correlations were observed between weed density and plant LAI/NDVI for all MG in 2008 and MG IV through VI in 2009. These results suggest that increased seeding rates may help decrease weed pressure and improve soybean growth at early growth stages. However the response of weed pressure to seeding rate may vary over years and depend on MG soybean.

  9. Joint estimation of contemporary seed and pollen dispersal rates among plant populations.

    Science.gov (United States)

    Robledo-Arnuncio, J J

    2012-03-01

    There are few statistical methods for estimating contemporary dispersal among plant populations. A maximum-likelihood procedure is introduced here that uses pre- and post-dispersal population samples of biparentally inherited genetic markers to jointly estimate contemporary seed and pollen immigration rates from a set of discrete external sources into a target population. Monte Carlo simulations indicate that accurate estimates and reliable confidence intervals can be obtained using this method for both pollen and seed migration rates at modest sample sizes (100 parents/population and 100 offspring) when population differentiation is moderate (F(ST) ≥ 0.1), or by increasing pre-dispersal samples (to about 500 parents/population) when genetic divergence is weak (F(ST) = 0.01). The method exhibited low sensitivity to the number of source populations and achieved good accuracy at affordable genetic resolution (10 loci with 10 equifrequent alleles each). Unsampled source populations introduced positive biases in migration rate estimates from sampled sources, although they were minor when the proportion of immigration from the latter was comparatively low. A practical application of the method to a metapopulation of the Australian resprouter shrub Banksia attenuata revealed comparable levels of directional seed and pollen migration among dune groups, and the estimate of seed dispersal was higher than a previous estimate based on conservative assignment tests. The method should be of interest to researchers and managers assessing broad-scale nonequilibrium seed and pollen gene flow dynamics in plants.

  10. Non-linear direct effects of acid rain on leaf photosynthetic rate of terrestrial plants.

    Science.gov (United States)

    Dong, Dan; Du, Enzai; Sun, Zhengzhong; Zeng, Xuetong; de Vries, Wim

    2017-09-12

    Anthropogenic emissions of acid precursors have enhanced global occurrence of acid rain, especially in East Asia. Acid rain directly suppresses leaf function by eroding surface waxes and cuticle and leaching base cations from mesophyll cells, while the simultaneous foliar uptake of nitrates in rainwater may directly benefit leaf photosynthesis and plant growth, suggesting a non-linear direct effect of acid rain. By synthesizing data from literature on acid rain exposure experiments, we assessed the direct effects of acid rain on leaf photosynthesis across 49 terrestrial plants in China. Our results show a non-linear direct effect of acid rain on leaf photosynthetic rate, including a neutral to positive effect above pH 5.0 and a negative effect below that pH level. The acid rain sensitivity of leaf photosynthesis showed no significant difference between herbs and woody species below pH 5.0, but the impacts above that pH level were strongly different, resulting in a significant increase in leaf photosynthetic rate of woody species and an insignificant effect on herbs. Our analysis also indicates a positive effect of the molar ratio of nitric versus sulfuric acid in the acid solution on leaf photosynthetic rate. These findings imply that rainwater acidity and the composition of acids both affect the response of leaf photosynthesis and therefore result in a non-linear direct effect. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. Plant Growth Models Using Artificial Neural Networks

    Science.gov (United States)

    Bubenheim, David

    1997-01-01

    In this paper, we descrive our motivation and approach to devloping models and the neural network architecture. Initial use of the artificial neural network for modeling the single plant process of transpiration is presented.

  12. Thermographic visualization of leaf response in cucumber plants infected with the soil-borne pathogen Fusarium oxysporum f. sp. cucumerinum.

    Science.gov (United States)

    Wang, Min; Ling, Ning; Dong, Xian; Zhu, Yiyong; Shen, Qirong; Guo, Shiwei

    2012-12-01

    Infection with the soil-borne pathogen Fusarium oxysporum f. sp. cucumerinum (FOC), which causes Fusarium wilt of cucumber plants, might result in changes in plant transpiration and water status within leaves. To monitor leaf response in cucumber infected with FOC, digital infrared thermography (DIT) was employed to detect changes in leaf temperature. During the early stages of FOC infection, stomata closure was induced by ABA in leaves, resulting in a decreased transpiration rate and increased leaf temperature. Subsequently, cell death occurred, accompanied by water loss, resulting in a little decrease in leaf temperature. A negative correlation between transpiration rate and leaf temperature was existed. But leaf temperature exhibited a special pattern with different disease severity on light-dark cycle. Lightly wilted leaves had a higher temperature in light and a lower temperature in dark than did in healthy leaves. We identified that the water loss from wilted leaves was regulated not by stomata but rather by cells damage caused by pathogen infection. Finally, water balance in infected plants became disordered and dead tissue was dehydrated, so leaf temperature increased again. These data suggest that membrane injury caused by FOC infection induces uncontrolled water loss from damaged cells and an imbalance in leaf water status, and ultimately accelerate plant wilting. Combining detection of the temperature response of leaves to light-dark conditions, DIT not only permits noninvasive detection and indirect visualization of the development of the soil-borne disease Fusarium wilt, but also demonstrates certain internal metabolic processes correlative with water status.

  13. Impact of proximity of thermoelectric power plants on bronchial obstructive crisis rates.

    Science.gov (United States)

    Ugarte-Avilés, Tamara; Manterola, Carlos; Cartes-Velásquez, Ricardo; Otzen, Tamara

    2017-01-19

    Environmental pollution is a risk factor for cardiorespiratory diseases. Energy generated by thermoelectric power plants (TEPP) represents a relevant source of pollution. The aim of this study was to evaluate the relationship between living near a coal-fired TEPP and the consultation rates for bronchial obstructive crises (BOC) in the province of Concepción, Chile. Population-based study. The epidemiological weeks from 2012 to 2014 were analyzed. The dependent variable was the emergency consultation rate for BOC in two health centers within 5 km of a TEPP (Coronel) and two that were more than 40 Km away from a TEPP (Talcahuano). The independent variables were the commune, climatological variables (air temperature and relative atmospheric humidity), environmental pollutants (PM10, PM2.5 and nitrogen oxide), weeks with the highest consultation rate and the years. Rates, Pearson's correlation and gross risk measures were calculated and adjusted for environmental and climatological variables. BOC rates were significantly higher in Coronel (RR = 4.9 95% CI 4.0-5.8; p < 0.05). The PM2.5 it showed the strongest correlation with BOC rates (r = 0.3; p < 0.01) in Coronel, but not Talcahuano. Linear regression modelling indicated that proximity to a TEPP (health center location) and temperature explained 26 and 18% of the variance in BOC rates, respectively. Rates of emergency consultation for BOC were significantly higher among a population living within 5 km of a coal-fired TEPP than those living 40 km away.

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

    Science.gov (United States)

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

    2010-01-01

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

  15. BIOMETRIC AND PHYSIOLOGICAL CHARACTERISTICS OF CHRYSANTHEMUM (CHRYSANTHEMUM INDICUM L. PLANTS GROWN AT DIFFERENT RATES OF NITROGEN FERTILIZATION

    Directory of Open Access Journals (Sweden)

    V IVANOVA

    2003-07-01

    Full Text Available A trial with large the flowered chrysanthemum cultivar Dark Westland was carried out in an unheated greenhouse. Three rates of nitrogen fertilization were studied: 0, 100 and 140 kgN/ha, as well as two modes of plant formation – single- and two-stemmed plants. Parameters of the biometric characteristics, leaf gasexchange and leaf pigment content were determined. The best results about growth and decorative behaviour were achieved at nitrogen fertilization level of 100 kgN/ha. It was established that nitrogen fertilization in rates of 100 and 140 kgN/ha enhances photosynthetic rate in both modes of plant formation.

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

    Science.gov (United States)

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

    2012-07-01

    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.

  17. Flexible Transpiration Cooled Thermal Protection System for Inflatable Atmospheric Capture and Entry Systems Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Andrews Space, Inc. proposes an innovative transpiration cooled aerobrake TPS design that is thermally protective, structurally flexible, and lightweight. This...

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

    Science.gov (United States)

    Gray, C. M.; Fierer, N.

    2013-12-01

    Our knowledge of microbial production and consumption of volatile organic compounds (VOCs) from soil and litter, as well as which microorganisms are involved, is relatively limited compared to what we know about VOC emissions from terrestrial plants. With climate change expecting to alter plant community composition, nitrogen (N) deposition rates, mean annual temperatures, precipitation patterns, and atmospheric VOC concentrations, it is unknown how microbial production and consumption of VOCs from litter and soil will respond. We have spent the last 5 years quantifying VOC flux rates in decaying plant litter, mineral soils and from a subalpine field site using a proton transfer reaction mass spectrometer (PTR-MS). Microbial production, relative to abiotic sources, accounted for 78% to 99% of the total VOC emissions from decomposing litter, highlighting the importance of microbial metabolisms in these systems. Litter chemistry correlated with the types of VOCs emitted, of which, methanol was emitted at the highest rates from all studies. The net emissions of carbon as VOCs was found to be up to 88% of that emitted as CO2 suggesting that VOCs likely represent an important component of the carbon cycle in many terrestrial systems. Nitrogen additions drastically reduced VOC emissions from litter to near zero, though it is still not understood whether this was due to an increase in consumption or a decrease in production. In the field, the root system contributed to 53% of the carbon that was emitted as VOCs from the soil with increasing air temperatures correlating to an increase in VOC flux rates from the soil system. Finally, we are currently utilizing next generation sequencing techniques (Illumina MiSeq) along with varying concentrations of isoprene, the third most abundant VOC in the atmosphere behind methane and methanol, above soils in a laboratory incubation to determine consumption rates and the microorganisms (bacteria, archaea and fungi) associated with the

  19. Improvement of Drought Tolerance in Transgenic Tobacco Plants by a Dehydrin-Like Gene Transfer

    Institute of Scientific and Technical Information of China (English)

    SHEN Ye; JIA Wei-long; ZHANG Yan-qin; HU Yuan-lei; WU Qi; LIN Zhong-ping

    2004-01-01

    A full-length cDNA of dehydrin BcDh2 from Boea crassifolia and its antisense nucleotide sequence have been transferred into tobacco (Nicotiana tabacum) NC89 under the control of a caulifower mosaic virus 35S promoter. Under a progressive water stress, photosynthetic rate, transpiration rate and stomatal conductance of the sense and antisense plants reduced, and those of the control reduced much more. Photosynthetic rate, transpiration rate and stomatal conductance of all plants tested increased significantly 24 hours later after recoveried water supply, and those of the sense and antisense plants were higher than control. These indicated that overexpression of a dehydrin gene in tobacco may improve tolerance to water stress for plants, however, antisense BcDh2 gene in transgenic plant did not influence physiological conditions. The results of germination experiment of the transgenic seeds showed that on MS medium with different concentration PEG (8000), sense seed could more endure drought than control, while antisense seed was sensitive to drought. The results suggested that the overexpression of a dehydrin gene in tobacco might improve the tolerance to water stress for plants.

  20. Improvement of Drought Tolerance in Transgenic Tobacco Plants by aDehydrin-Like Gene Transfer

    Institute of Scientific and Technical Information of China (English)

    SHENYe; JIAWei-long; ZHANGYan-qin; HUYuan-lei; WUQi; LINZhongping

    2004-01-01

    A full-length cDNA of dehydrin BcDh2 from Boea crassifolia and its antisense nucleotide sequence have been transferred into tobacco (Nicotiana tabacum) NC89 under the control of a caulifower mosaic virus 35S promoter. Under a progressive water stress, photosynthetic rate, transpiration rate and stomatal conductance of the sense and antisense plants reduced, and those of the control reduced much more. Photosynthetic rate, transpiration rate and stomatal conductance of all plants tested increased significantly 24 hours later after recoveried water supply, and those of the sense and antisense plants were higher than control. These indicated that overexpression of a dehydrin gene in tobacco may improve tolerance to water stress for plants, however, antisense BcDh2 gene in transgenic plant did not influence physiological conditions. The results of germination experiment of the transgenic seeds showed that on MS medium with different concentration PEG (8000), sense seed could more endure drought than control, while antisense seed was sensitive to drought. The results suggested that the overexpression of a dehydrin gene in tobacco might improve the tolerance to water stress for plants.

  1. Enhancement of the Initial Growth Rate of Agricultural Plants by Using Static Magnetic Fields.

    Science.gov (United States)

    Kim, Seung C; Mason, Alex; Im, Wooseok

    2016-07-08

    Electronic devices and high-voltage wires induce magnetic fields. A magnetic field of 1,300-2,500 Gauss (0.2 Tesla) was applied to Petri dishes containing seeds of Garden Balsam (Impatiens balsamina), Mizuna (Brassica rapa var. japonica), Komatsuna (Brassica rapa var. perviridis), and Mescluns (Lepidium sativum). We applied magnets under the culture dish. During the 4 days of application, we observed that the stem and root length increased. The group subjected to magnetic field treatment (n = 10) showed a 1.4 times faster rate of growth compared with the control group (n = 11) in a total of 8 days (p abnormal arrangements. However, the exact cause remains unclear. These results of growth enhancement of applying magnets suggest that it is possible to enhance the growth rate, increase productivity, or control the speed of germination of plants by applying static magnetic fields. Also, magnetic fields can cause physiological changes in plant cells and can induce growth. Therefore, stimulation with a magnetic field can have possible effects that are similar to those of chemical fertilizers, which means that the use of fertilizers can be avoided.

  2. Assessing HYDRUS-2D model to estimate soil water contents and olive tree transpiration fluxes under different water distribution systems

    Science.gov (United States)

    Autovino, Dario; Negm, Amro; Rallo, Giovanni; Provenzano, Giuseppe

    2016-04-01

    In Mediterranean countries characterized by limited water resources for agricultural and societal sectors, irrigation management plays a major role to improve water use efficiency at farm scale, mainly where irrigation systems are correctly designed to guarantee a suitable application efficiency and the uniform water distribution throughout the field. In the last two decades, physically-based agro-hydrological models have been developed to simulate mass and energy exchange processes in the soil-plant-atmosphere (SPA) system. Mechanistic models like HYDRUS 2D/3D (Šimunek et al., 2011) have been proposed to simulate all the components of water balance, including actual crop transpiration fluxes estimated according to a soil potential-dependent sink term. Even though the suitability of these models to simulate the temporal dynamics of soil and crop water status has been reported in the literature for different horticultural crops, a few researches have been considering arboreal crops where the higher gradients of root water uptake are the combination between the localized irrigation supply and the three dimensional root system distribution. The main objective of the paper was to assess the performance of HYDRUS-2D model to evaluate soil water contents and transpiration fluxes of an olive orchard irrigated with two different water distribution systems. Experiments were carried out in Castelvetrano (Sicily) during irrigation seasons 2011 and 2012, in a commercial farm specialized in the production of table olives (Olea europaea L., var. Nocellara del Belice), representing the typical variety of the surrounding area. During the first season, irrigation water was provided by a single lateral placed along the plant row with four emitters per plant (ordinary irrigation), whereas during the second season a grid of emitters laid on the soil was installed in order to irrigate the whole soil surface around the selected trees. The model performance was assessed based on the

  3. Anatomical Basis for Optimal Use of Water for Maintenance of Three Xerophytic Plants

    Directory of Open Access Journals (Sweden)

    Abdullahi Alanamu ABDULRAHAMAN

    2012-05-01

    Full Text Available Three xerophytic plant species namely Agave americana Linn., Aloe vera Tourn. and Linn. and Euphorbia milii Des Moul. were propagated in a greenhouse each with 5 varying soil moisture contents i.e. 1.25%, 2.5%, 5%, 10%, and 20% and subjected to 4 watering frequencies i.e. daily, weekly, biweekly and monthly. Euphorbia milii was the most xerophytic species having relatively lower rate of transpiration than Aloe vera and Agave americana. It was suggested that the high rate of transpiration in Aloe vera and Agave americana may be due to the large tetracytic stomata as compared to the small paracytic stomata of Euphorbia milii. It was also observed that Aloe vera was least tolerant of high soil moisture in daily watering as well as low soil moisture in monthly regime. Agave americana and Euphorbia milii were species that were more robust with capacity to cope well with low and high watering regimes than Aloe vera.

  4. Relationships of photosynthesis and transpiration of Populus euphratica with their affecting factors%胡杨光合蒸腾与影响因子间关系的研究

    Institute of Scientific and Technical Information of China (English)

    曹生奎; 冯起; 司建华; 常宗强; 陈克龙; 曹广超

    2012-01-01

    In this research we studied correlations between the photosynthetic and transpiration rate of Populus euphratica and their affecting factors. Results showed that photosynthetic rate was logarithmically related to stomatal conductance; The relation between transpiration rate and stomatal conductance was lineal. They both polyno-mially associated with photosynthetically active radiation, and binomially with air temperature. There also indica- ted that P. euphratica belonged to the plants limited by stomata. Stomatal conductance and photosynthetically ac- tive radiation commonly decided the magnitude of photosynthetic and transpiration rate. Air temoerature, and rein-tive humanity affected them by means of stomatal conductance. The conditions that P. euphratica adapt to photo- synthetic gas exchange were that photosynthetically active radiation kept about 1700μmol·m^-2·s^-1, temperature was nearly 350℃ and relative humanity was 20% -30% or so.%对胡杨光合速率和蒸腾速率同各主要影响因子间相关关系进行了研究。结果表明:胡杨光合速率和气孔导度1司呈对数关系,蒸腾速率与气孔导度间呈线性关系;两者与光合有效辐射均呈多项式关系;与空气温度均呈二项式关系。结果说明胡杨属气孔限制型植物,气孔导度和光合有效辐射共同决定胡杨的光合和蒸腾作用。气温和相对湿度通过影响胡杨的气孔导度进而影响胡杨的光合速率和蒸腾速率。适宜胡杨进行光合气体交换的环境条件是光合有效辐射保持在1700μmol·m^-2·s^-1左右,温度保持在35℃左右,相对湿度保持在20%-30%间。

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

    Science.gov (United States)

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

    2012-01-01

    The growth rate hypothesis (GRH) proposes that higher growth rate (the rate of change in biomass per unit biomass, μ) 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, μ 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 μ, increasing for small values of μ, reaching a maximum, and then decreasing. The range of variations in μ was positively correlated with variation in C:N:P stoichiometry. Furthermore, μ 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.

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

    Directory of Open Access Journals (Sweden)

    Qiang Yu

    Full Text Available The growth rate hypothesis (GRH proposes that higher growth rate (the rate of change in biomass per unit biomass, μ 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, μ 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 μ, increasing for small values of μ, reaching a maximum, and then decreasing. The range of variations in μ was positively correlated with variation in C:N:P stoichiometry. Furthermore, μ 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.

  7. The Effect of Bio-Fertilizers on Plant Growth and Growth Rate of Grafted Avocado (Persea americana Mill.

    Directory of Open Access Journals (Sweden)

    Lazarus Agus Sukamto

    2014-01-01

    Full Text Available Avocado (Persea americana Mill. is considered the most nutritious of all fruits. Avocado fruit contain high unsaturated fat, protein, and energy. It could be eaten fresh for food, drinks, cooking, and cosmetics. Recently, it has become a significant commodity in international trade. Indonesia is the 2nd avocado producing country, but only little quantity of avocado fruits could be exported. The farmers usually grow avocado plants from the seeds, without proper fertilizers in their backyards or small gardens. The problems could be solved by using grafted plants, proper fertilizers, and growing in a large scale of areas. This research was conducted to find out the effect of two liquid bio-fertilizers namely Mega Rhizo and Beyonic StarTmik on the plant growth and growth rate of grafted avocado plants. Some plant growths and growth rates of grafted avocado were influenced significantly by genotype accession, kind of bio-fertilizer, and weather (temperature.  Plant growth and growth rate of most avocado accessions were not significant differences to bio-fertilizer applications, but some avocado accessions on certain months were significant differently. Growth rate ranks of plant height based on accession were no. 10, 28, 13, 1, 5, 2, and 14 consecutively. Those of canopy width were no. 28, 10, 1, 2, 14, 5, and 13 consecutively. Those of trunk diameters were no. 28, 10, 2, 5, 1, 13, and 14 consecutively. All growth rate ranks based on bio-fertilizer were Mega Rhizo, Beyonic StarTmik, and control consecutively.

  8. Water relations and transpiration of quinoa (Chenopodium quinoa Willd.) under salinity and soil drying

    DEFF Research Database (Denmark)

    Razzaghi, Fatemeh; Ahmadi, Seyed Hamid; Adolf, Verena Isabelle

    2011-01-01

    Drought and salinity are the two major factors limiting crop growth and production in arid and semi-arid regions. The separate and combined effects of salinity and progressive drought in quinoa (Chenopodium quinoa Willd.) were studied in a greenhouse experiment. Stomatal conductance (gs), leaf...... water potential (Wl), shoot and root abscisic acid concentration ([ABA]) and transpiration rate were measured in full irrigation (FI; around 95 % of water holding capacity (WHC)) and progressive drought (PD) treatments using the irrigation water with five salinity levels (0, 10, 20, 30 and 40 dS m)1......); the treatments are referred to as FI0, FI10, FI20, FI30, FI40; PD0, PD10, PD20, PD30, PD40, respectively. The measurements were carried out over 9 days of continuous drought. The results showed that increasing salinity levels decreased the total soil water potential (WT) and consequently decreased gs and Wl...

  9. Plant diversity does not buffer drought effects on early-stage litter mass loss rates and microbial properties.

    Science.gov (United States)

    Vogel, Anja; Eisenhauer, Nico; Weigelt, Alexandra; Scherer-Lorenzen, Michael

    2013-09-01

    Human activities are decreasing biodiversity and changing the climate worldwide. Both global change drivers have been shown to affect ecosystem functioning, but they may also act in concert in a non-additive way. We studied early-stage litter mass loss rates and soil microbial properties (basal respiration and microbial biomass) during the summer season in response to plant species richness and summer drought in a large grassland biodiversity experiment, the Jena Experiment, Germany. In line with our expectations, decreasing plant diversity and summer drought decreased litter mass loss rates and soil microbial properties. In contrast to our hypotheses, however, this was only true for mass loss of standard litter (wheat straw) used in all plots, and not for plant community-specific litter mass loss. We found no interactive effects between global change drivers, that is, drought reduced litter mass loss rates and soil microbial properties irrespective of plant diversity. High mass loss rates of plant community-specific litter and low responsiveness to drought relative to the standard litter indicate that soil microbial communities were adapted to decomposing community-specific plant litter material including lower susceptibility to dry conditions during summer months. Moreover, higher microbial enzymatic diversity at high plant diversity may have caused elevated mass loss of standard litter. Our results indicate that plant diversity loss and summer drought independently impede soil processes. However, soil decomposer communities may be highly adapted to decomposing plant community-specific litter material, even in situations of environmental stress. Results of standard litter mass loss moreover suggest that decomposer communities under diverse plant communities are able to cope with a greater variety of plant inputs possibly making them less responsive to biotic changes.

  10. Plant response of onion cultivars developed from greenhouse-grown transplants to plant density and fertilizer rate

    Science.gov (United States)

    Onions (Allium cepa L.) can be established from seed or transplants. The latter planting material can be dormant or actively growing when transplanted to the field. Onion transplants can be produced in a greenhouse, but there are gaps in the knowledge of the cultural requirements for these plants ...

  11. Transpiration and Groundwater Uptake Dynamics of Pinus Brutia on a Fractured Mediterranean Mountain Slope during Two Hydrologically Contrasting Years

    Science.gov (United States)

    Eliades, Marinos; Bruggeman, Adriana; Lubczynski, Maciek; Christou, Andreas; Camera, Corrado; Djuma, Hakan

    2017-04-01

    Semi-arid environments tend to have extreme temporal variability in rainfall, resulting in extended periods with little to no precipitation. The mountainous topography is characterized by steep slopes, often leading to shallow soil layers with limited water storage capacity. Tree species survive in these environments by developing various adaptation mechanisms to access water. The main objective of this study is to examine the differences of two hydrologically contrasting years on the transpiration and groundwater uptake dynamics of Pinus brutia trees. We selected four trees for sap flow monitoring in an 8966-m2 fenced area of Pinus brutia forest. The site is located at 620 m elevation, on the northern foothills of the Troodos mountains in Cyprus. The slope of the site ranges between 0 and 82%. The average daily minimum temperature is 5 0C in January and the average daily maximum temperature is 35 oC in August. The mean annual rainfall is 425 mm. Monitoring started on 1 January 2015 and is ongoing. We measured soil depth in a 1-m grid around each of the selected trees for monitoring. We processed soil depths in ArcGIS software (ESRI) to create a soil depth map. We used a Total Station and a differential GPS for the creation of a high resolution DEM of the area covering the selected trees. We installed seventeen soil moisture sensors at 12-cm depth and two at 30-cm depth, where the soil was deeper than 24 cm. We randomly installed 28 metric manual rain gauges under the trees' canopy to measure throughfall. For stemflow we installed a plastic tube around each tree trunk and connected it to a manual rain gauge. We used sap flow heat ratio method (HRM) instruments to determine sap flow rates of the Pinus brutia. Hourly meteorological conditions were observed by an automatic meteorological station. Here we present the results of the January to October periods, in order to have comparable results for the two contrasting years. During the wet year of 2015, we measured 439

  12. Planting Date and Seeding Rate Effects on Sunn Hemp Biomass and Nitrogen Production for a Winter Cover Crop

    Directory of Open Access Journals (Sweden)

    Kipling S. Balkcom

    2011-01-01

    Full Text Available Sunn hemp (Crotalaria juncea L. is a tropical legume that produces plant biomass and nitrogen (N quickly. Our objectives were to assess the growth of a new sunn hemp cultivar breed to produce seed in a temperate climate and determine the residual N effect on a rye (Secale cereale L. cover crop in east-central Alabama from 2007 to 2009. Plant populations, plant height, stem diameter, biomass production, and N content were determined for two sunn hemp planting dates, following corn (Zea mays L. and wheat (Triticum aestivum L. harvest, across different seeding rates (17, 34, 50, and 67 kg/ha. Rye biomass was measured the following spring. Sunn hemp biomass production was inconsistent across planting dates, but did relate to growing degree accumulation. Nitrogen concentrations were inversely related to biomass production, and subsequent N contents corresponded to biomass levels. Neither planting date nor seeding rate affected rye biomass production, but rye biomass averaged over both planting dates following wheat/sunn hemp averaged 43% and 33% greater than rye following fallow. Rye biomass following corn/sunn hemp was equivalent to fallow plots. Early planting dates are recommended for sunn hemp with seeding rates between 17 and 34 kg/ha to maximize biomass and N production.

  13. Engineering rhizosphere hydraulics: pathways to improve plant adaptation to drought

    Science.gov (United States)

    Ahmed, Mutez; Zarebanadkouki, Mohsen; Ahmadi, Katayoun; Kroener, Eva; Kostka, Stanley; Carminati, Andrea

    2017-04-01

    Developing new technologies to optimize the use of water in irrigated croplands is of increasing importance. Recent studies have drawn attention to the role of mucilage in shaping rhizosphere hydraulic properties and regulating root water uptake. During drying mucilage keeps the rhizosphere wet and conductive, but upon drying it turns hydrophobic limiting root water uptake. Here we introduced the concept of rhizoligands, defined as additives that 1) rewet the rhizosphere and 2) reduce mucilage swelling hereby reducing the rhizosphere conductivity. We then tested its effect on rhizosphere water dynamics and transpiration. The following experiments were carried out to test if selected surfactants behave as a rhizoligand. We used neutron radiography to monitor water redistribution in the rhizosphere of lupine and maize irrigated with water and rhizoligand solution. In a parallel experiment, we tested the effect of rhizoligand on the transpiration rate of lupine and maize subjected to repeated drying and wetting cycles. We also measured the effect of rhizoligand on the maximum swelling of mucilage and the saturated hydraulic conductivity of soil mixed with various mucilage concentrations. The results were then simulated using a root water uptake model. Rhizoligand treatment quickly and uniformly rewetted the rhizosphere of maize and lupine. Interestingly, rhizoligand also reduced transpiration during drying/wetting cycles. Evaporation from the bare soil was of minor importance. Our hypothesis is that the reduction in transpiration was triggered by the interaction between rhizoligand and mucilage exuded by roots. This hypothesis is supported by the fact that rhizoligand reduced the maximum swelling of mucilage, increased its viscosity, and decreased the hydraulic conductivity of soil-mucilage mixtures. The reduced conductivity of the rhizosphere induced a moderate stress to the plants reducing transpiration. Simulation with a reduced hydraulic conductivity of the

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

    NARCIS (Netherlands)

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

    1992-01-01

    Several authors have determined the sensitivity of transpiration to different environmental parameters using the Penman-Monteith equation. In their studies the interaction between transpiration and, for example, the humidity of the air is ignored: the feedback with the planetary boundary layer (PBL)

  15. Transpiration of oak trees in the oak savannas of the Southwestern Borderlands region

    Science.gov (United States)

    Peter F. Ffolliott; Cody L. Stropki; Aaron T. Kauffman; Gerald J. Gottfried

    2008-01-01

    Transpiration of oak trees on the Cascabel watersheds in the savannas on the eastern slope of the Peloncillo Mountains in southwestern New Mexico has been estimated by the sap-flow method. Transpiration represents the largest loss of gross precipitation falling on a watershed in approximations of water budgets for the more densely stocked oak woodlands of the...

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

    Science.gov (United States)

    Sade, Nir; Gebremedhin, Alem; Moshelion, Menachem

    2012-07-01

    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 (Ψleaf) when water is abundant, as well as under drought conditions, by reducing stomatal conductance as necessary to limit transpiration. Anisohydric plants have more variable Ψleaf 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.

  17. Responses of plant growth rate to nitrogen supply: a comparison of relative addition and N interruption treatments.

    Science.gov (United States)

    Walker, R L; Burns, I G; Moorby, J

    2001-02-01

    This paper investigates the effects of uptake of nitrate and the availability of internal N reserves on growth rate in times of restricted supply, and examines the extent to which the response is mediated by the different pools of N (nitrate N, organic N and total N) in the plant. Hydroponic experiments were carried out with young lettuce plants (Lactuca sativa L.) to compare responses to either an interruption in external N supply or the imposition of different relative N addition rate (RAR) treatments. The resulting relationships between whole plant relative growth rate (RGR) and N concentration varied between linear and curvilinear (or possibly bi-linear) forms depending on the treatment conditions. The relationship was curvilinear when the external N supply was interrupted, but linear when N was supplied by either RAR methods or as a supra-optimal external N supply. These differences resulted from the ability of the plant to use external sources of N more readily than their internal N reserves. These results show that when sub-optimal sources of external N were available, RGR was maintained at a rate which was dependent on the rate of nitrate uptake by the roots. Newly acquired N was channelled directly to the sites of highest demand, where it was assimilated rapidly. As a result, nitrate only tended to accumulate in plant tissues when its supply was essentially adequate. By comparison, plants forced to rely solely on their internal reserves were never able to mobilize and redistribute N between tissues quickly enough to prevent reductions in growth rate as their tissue N reserves declined. Evidence is presented to show that the rate of remobilization of N depends on the size and type of the N pools within the plant, and that changes in their rates of remobilization and/or transfer between pools are the main factors influencing the form of the relationship between RGR and N concentration.

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

    Energy Technology Data Exchange (ETDEWEB)

    Fayer, M.J.; Richmond, M.C.; Wigmosta, M.S. [Pacific Northwest National Lab., Richland, WA (United States); Kelley, M.E. [Battelle Environmental Restoration Dept., Columbus, OH (United States)

    1998-04-01

    In FY 1996, the Pacific Northwest National Laboratory (PNNL) provided technical assistance to Battelle Columbus Operations (BCO) in their ongoing assessment of contaminant migration at the Pantex Plant in Amarillo, Texas. The objective of this report is to calculate deep drainage rates at the Pantex Plant. These deep drainage rates may eventually be used to predict contaminant loading to the underlying unconfined aquifer for the Pantex Plant Baseline Risk Assessment. These rates will also be used to support analyses of remedial activities involving surface alterations or the subsurface injection withdrawal of liquids or gases. The scope of this report is to estimate deep drainage rates for the major surface features at the Pantex Plant, including ditches and playas, natural grassland, dryland crop rotation, unvegetated soil, and graveled surfaces. Areas such as Pantex Lake that are outside the main plant boundaries were not included in the analysis. All estimates were derived using existing data or best estimates; no new data were collected. The modeling framework used to estimate the rates is described to enable future correlations, improvements, and enhancements. The scope of this report includes only data gathered during FY 1996. However, a current review of the data gathered on weather, soil, plants, and other information in the time period since did not reveal anything that would significantly alter the results presented in this report.

  19. A Comparison of the Effects of Two Arbuscular Mycorrhizal Fungal Species on Photosynthesis, Transpiration and Water Use Efficiency of Wheat%两种丛枝菌根菌抗旱效应的比较

    Institute of Scientific and Technical Information of China (English)

    叶爱华; 袁艺; 杨莉; 蔡永萍; 田胜尼

    2003-01-01

    Drought is a major restriction to plant growth. AMF(arbuscular mycorrhizal fungi)can increase the absorption of nutrition, facilitate the growth of plant and improve drought resistance of many plants. The experiment compared the effects of two AMF species on wheat at 10% water level. The wheat inoculated with 90089 and 90036 decreased stomatal resistance, increased net photosynthetic rate, stomatal conduction,transpiration rate and WUE compared with the control.%丛枝菌根可在与植物共生的过程中增加植物对营养元素的吸收,增加植物的生长量,提高植物的抗旱抗涝性.在盆栽条件下,水分控制在10%左右时,接菌的小麦和对照相比降低了气孔的阻力,提高了叶片气孔传导力,蒸腾速率,有效光合作用和水平利用效率.

  20. Sensitivity of transpiration to subsurface properties: Exploration with a 1-D model

    Science.gov (United States)

    Vrettas, Michail D.; Fung, Inez Y.

    2017-06-01

    The amount of moisture transpired by vegetation is critically tied to the moisture supply accessible to the root zone. In a Mediterranean climate, integrated evapotranspiration (ET) is typically greater in the dry summer when there is an uninterrupted period of high insolation. We present a 1-D model to explore the subsurface factors that may sustain ET through the dry season. The model includes a stochastic parameterization of hydraulic conductivity, root water uptake efficiency, and hydraulic redistribution by plant roots. Model experiments vary the precipitation, the magnitude and seasonality of ET demand, as well as rooting profiles and rooting depths of the vegetation. The results show that the amount of subsurface moisture remaining at the end of the wet winter is determined by the competition among abundant precipitation input, fast infiltration, and winter ET demand. The weathered bedrock retains ˜30% of the winter rain and provides a substantial moisture reservoir that may sustain ET of deep-rooted (>8 m) trees through the dry season. A small negative feedback exists in the root zone, where the depletion of moisture by ET decreases hydraulic conductivity and enhances the retention of moisture. Hence, hydraulic redistribution by plant roots is impactful in a dry season, or with a less conductive subsurface. Suggestions for implementing the model in the CESM are discussed.

  1. Corrosion circumstance in the Tokai Reprocessing Plant and evaluation of the corrosion rate

    Energy Technology Data Exchange (ETDEWEB)

    Maki, Akira [Japan Nuclear Cycle Development Inst., Tokai Works, Tokai Reprocessing Center, Tokai, Ibaraki (Japan)

    2002-03-01

    In the reprocessing plant, corrosive circumstances arise, because the major equipment contains a high concentration of the metal ions that originate from the fission products. They are also equipped in the various concentrations of nitric acid and various temperatures. Based on failed experiments due to corrosion, repairing the equipment and exchanging materials, the corrosion rate of stainless steel containing Nb was measured over 1 mm/yr in the heat transfer surface of the dissolver. Pin-holes in the weld zone of the heat conduction surface of the dissolver and the acid recovery evaporator were observed. Although the corrosion rate of Ti-5Ta in the vapor zone of the plutonium solution evaporator reached 0.1 - 0.3 mm/yr, no local attacks were confirmed. On the other hand, the corrosion of Ti-5Ta was not observed in the acid recovery evaporator. This report presents the survey result of the corrosion equipment and an outline of the corrosion tests, with the wall thickness measurement result obtained as a soundness confirmation of the equipment. (author)

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

    Science.gov (United States)

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

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

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

    Science.gov (United States)

    Liu, Xiaozhen; Zhang, Shuoxin

    2010-05-01

    Water is essential for plants and involves most physical and chemical processes within their lifecycles. Drought stress is a crucial limiting factor for plant growth and production. 48% of the land in China is arid and semi-arid, and non-irrigated land occupies approximately 51.9% of the total cultivated areas. Therefore, studies on plant drought resistant mechanisms have great significance for improving water use efficiency and thus increasing productivity of economical plants. Prior research has shown that the application of nitrogenous fertilizer affects the drought-resistant characteristics of plants. This study aimed to reveal the effect of nitrogenous fertilizer on physiological aspects and its impact on the drought resistance of four tree species (Robinia pseudoacacia L., Ligustrum lucidum Ait., Acer truncatum Bge. and Ulmus pumila L. ) in northwest China. Three levels of nitrogen fertilization (46% N based of urea adjusted to: 5g/15g soil, 15g/15g soil and 25g/15g soil) and an additional control study were applied to 2-year-old well-grown seedlings under drought conditions (30% field moisture capacity). Stomatal conductance, transpiration rate and net photosynthetic rate were measured by a LI-6400 photosynthesis system, while water use efficiency was calculated from net photosynthesis rate and transpiration rate. The results revealed that as the amount of urea applied was raised, stomatal conductance, transpiration rate and net photosynthetic rate decreased significantly, and thus water use efficiency significantly increased. It is therefore concluded that the application of nitrogenous fertilizer regulated physiological parameters by reducing stomata conductance to improve water use efficiency. In addition, among the four tree species, U. pumila had the maximum value of water use efficiency under the same drought condition. The outcome of this study provides a guided option for forest management in arid and semi-arid areas of northwest China.

  4. Interactions between plant size and canopy openness influence vital rates and life-history tradeoffs in two neotropical understory herbs.

    Science.gov (United States)

    Westerband, Andrea C; Horvitz, Carol C

    2015-08-01

    • For tropical forest understory plants, the ability to grow, survive, and reproduce is limited by the availability of light. The extent to which reproduction incurs a survival or growth cost may change with light availability, plant size, and adaptation to shade, and may vary among similar species.• We estimated size-specific rates of growth, survival, and reproduction (vital rates), for two neotropical understory herbs (order Zingiberales) in a premontane tropical rainforest in Costa Rica. During three annual censuses we monitored 1278 plants, measuring leaf area, number of inflorescences, and canopy openness. We fit regression models of all vital rates and evaluated them over a range of light levels. The best fitting models were selected using Akaike's Information Criterion.• All vital rates were significantly influenced by size in both species, but not always by light. Increasing light resulted in higher growth and a higher probability of reproduction in both species, but lower survival in one species. Both species grew at small sizes but shrank at larger sizes. The size at which shrinkage began differed among species and light environments. Vital rates of large individuals were more sensitive to changes in light than small individuals.• Increasing light does not always positively influence vital rates; the extent to which light affects vital rates depends on plant size. Differences among species in their abilities to thrive under different light conditions and thus occupy distinct niches may contribute to the maintenance of species diversity. © 2015 Botanical Society of America, Inc.

  5. Water balance measurements and simulations of maize plants on lysimeters

    Science.gov (United States)

    Heinlein, Florian; Biernath, Christian; Klein, Christian; Thieme, Christoph; Priesack, Eckart

    2016-04-01

    In Central Europe expected major aspects of climate change are a shift of precipitation events and amounts towards winter months, and the general increase of extreme weather events like heat waves or summer droughts. This will lead to strongly changing regional water availability and will have an impact on future crop growth, water use efficiency and yields. Therefore, to estimate future crop yields by growth models accurate descriptions of transpiration as part of the water balance is important. In this study, maize was grown on weighing lysimeters (sowdate: 24 April 2013). Transpiration was determined by sap flow measurement devices (ICT International Pty Ltd, Australia) using the Heat-Ratio-Method: two temperature probes, 0.5 cm above and below a heater, detect a heat pulse and its speed which allows the calculation of sap flow. Water balance simulations were executed with different applications of the model framework Expert-N. The same pedotransfer and hydraulic functions and the same modules to simulate soil water flow, soil heat and nitrogen transport, nitrification, denitrification and mineralization were used. Differences occur in the chosen potential evapotranspiration ETpot (Penman-Monteith ASCE, Penman-Monteith FAO, Haude) and plant modules (SPASS, CERES). In all simulations ETpot is separated into a soil and a plant part using the leaf are index (LAI). In a next step, these parts are reduced by soil water availability. The sum of these parts is the actual evapotranspiration ETact which is compared to the lysimeter measurements. The results were analyzed from Mid-August to Mid-September 2013. The measured sap flow rates show clear diurnal cycles except on rainy days. The SPASS model is able to simulate these diurnal cycles, overestimates the measurements on rainy days and at the beginning of the analyzed period, and underestimates transpiration on the other days. The main reason is an overestimation of potential transpiration Tpot due to too high

  6. Effects of sand burial on dune plants:a review

    Institute of Scientific and Technical Information of China (English)

    Hao Qu; HaLin Zhao; RuiLian Zhou

    2014-01-01

    Burial of different growth stages of plants (e.g., adult plants, seedlings and seeds) is frequent in dune ecosystems. The soil micro-environment, which differs from surface conditions, influences the survival and growth of dune plants. To sum up knowledge about the survival mechanisms of plants under sand burial and to promote practical rehabilitation of dune vegetation, we reviewed relevant published literature and concluded that:(1) Focus in recent years has been on impacts of sand burial on seed germination and seedling emergence. Generally, shallow burial increased seed germination and seed-ling emergence, but deeper burial was negative. Buried at the same depth, large seeds showed higher germination and seedling emergence rates, attributed to larger energy reserves. (2) Survival, growth and reproduction rates of dune plants show plasticity in response to sand burial. Long-term deep burial is fatal because it creates a physical barrier which overcomes the vertical growth of plants, reduces photosynthetic leaf area, and limits oxygen availability to roots. Modest burial, on the other hand, is advantageous for growth and reproduction of many dune plants, due to protection from ex-cessive temperature and drought. (3) There are few reports concerning effects of sand burial on plant physiology, but a limited number of studies indicate that partial burial increases water use efficiency, chlorophyll content, transpiration rate and net photosynthetic rates. The antioxidant protective enzyme system and osmolyte balance were reported to be involved in the mechanisms of dune plant resistance to burial.

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

    Science.gov (United States)

    Bachand, P.A.M.; S. Bachand,; Fleck, Jacob A.; Anderson, Frank E.; Windham-Myers, Lisamarie

    2014-01-01

    The current state of science and engineering related to analyzing wetlands overlooks the importance of transpiration and risks data misinterpretation. In response, we developed hydrologic and mass budgets for agricultural wetlands using electrical conductivity (EC) as a natural conservative tracer. We developed simple differential equations that quantify evaporation and transpiration rates using flowrates and tracer concentrations atwetland inflows and outflows. We used two ideal reactormodel solutions, a continuous flowstirred tank reactor (CFSTR) and a plug flow reactor (PFR), to bracket real non-ideal systems. From those models, estimated transpiration ranged from 55% (CFSTR) to 74% (PFR) of total evapotranspiration (ET) rates, consistent with published values using standard methods and direct measurements. The PFR model more appropriately represents these nonideal agricultural wetlands in which check ponds are in series. Using a fluxmodel, we also developed an equation delineating the root zone depth at which diffusive dominated fluxes transition to advective dominated fluxes. This relationship is similar to the Peclet number that identifies the dominance of advective or diffusive fluxes in surface and groundwater transport. Using diffusion coefficients for inorganic mercury (Hg) and methylmercury (MeHg) we calculated that during high ET periods typical of summer, advective fluxes dominate root zone transport except in the top millimeters below the sediment–water interface. The transition depth has diel and seasonal trends, tracking those of ET. Neglecting this pathway has profound implications: misallocating loads along different hydrologic pathways; misinterpreting seasonal and diel water quality trends; confounding Fick's First Law calculations when determining diffusion fluxes using pore water concentration data; and misinterpreting biogeochemicalmechanisms affecting dissolved constituent cycling in the root zone. In addition,our understanding of internal

  8. [Species-dependence of the pattern of plant photosynthetic rate response to light intensity transition from saturating to limiting one].

    Science.gov (United States)

    Chen, Yue; Xu, Da-Quan

    2007-12-01

    By observing the photosynthetic responses of leaves to changes in light intensity and CO(2) concentration it was found that among the more than 50 plant species examined 32 species and 25 species showed respectively the V pattern and L pattern of the photosynthetic response to light intensity transition from saturating to limiting one (Figs.1 and 2 and Table 1). The pattern of photosynthetic response to light intensity transition is species-dependent but not leaf developmental stage-dependent (Fig.3). The species-dependence was not related to classification in taxonomy because the photosynthetic response might display the two different patterns (V and L) in plants of the same family, for example, rice and wheat (Gramineae), soybean and peanut (Leguminosae). It seemed to be related to the pathway of photosynthetic carbon assimilation because all of the C(4) plants examined (maize, green bristlegrass and thorny amaranth) displayed the L pattern. It might be related to light environment where the plants originated. The V pattern of photosynthetic response to light intensity transition was often observed in some plants grown in shade habitats, for example, sweet viburnum and Japan fatsia, while the L pattern was frequently observed in those plants grown in sunny habitats, for example, ginkgo and cotton. Furthermore, the ratio of electron transport rate to carboxylation rate in vivo measured at limiting light was far higher in the V pattern plants (mostly higher than 10) than in the L pattern plants (mostly lower than 5), but the ratio measured at saturating light had no significant difference between the two kinds of plants (Table 2). These results can be explained in part by that the V pattern plant species have larger light-harvesting complex (LHCII) and at saturating light the reversible dissociation of some LHCIIs from PSII reaction center complex occurs. The pattern of photosynthetic response to light intensity transition and the ratio of electron transport rate

  9. A simple framework to analyze water constraints on seasonal transpiration in rubber tree (Hevea brasiliensis plantations

    Directory of Open Access Journals (Sweden)

    Jessada eSopharat

    2015-01-01

    Full Text Available Climate change and fast extension in climatically suboptimal areas threaten the sustainability of rubber tree cultivation. A simple framework based on reduction factors of potential transpiration was tested to evaluate the water constraints on seasonal transpiration in tropical sub-humid climates, according pedoclimatic conditions. We selected a representative, mature stand in a drought-prone area. Tree transpiration, evaporative demand and soil water availability were measured every day over 15 months. The results showed that basic relationships with evaporative demand, leaf area index and soil water availability were globally supported. However the implementation of a regulation of transpiration at high evaporative demand whatever soil water availability was necessary to avoid large overestimates of transpiration. The details of regulation were confirmed by the analysis of canopy conductance response to vapour pressure deficit. The final objective of providing hierarchy between the main regulation factors of seasonal and annual transpiration was achieved. In the tested environmental conditions, the impact of atmospheric drought appeared larger importance than soil drought contrary to expectations. Our results support the interest in simple models to provide a first diagnosis of water constraints on transpiration with limited data, and to help decision making towards more sustainable rubber plantations.

  10. Stomatal acclimation to vapour pressure deficit doubles transpiration of small tree seedlings with warming

    DEFF Research Database (Denmark)

    Marchin, Renée M.; Broadhead, Alice A.; Bostic, Laura E.

    2016-01-01

    .5-1.3 kPa on transpiration and stomatal conductance (gs ) of tree seedlings in the temperate forest understory (Duke Forest, North Carolina, USA). We observed peaked responses of transpiration to VPD in all seedlings, and the optimum VPD for transpiration (Dopt ) shifted proportionally with increasing...... chamber VPD. Warming increased mean water use of Carya by 140% and Quercus by 150%, but had no significant effect on water use of Acer. Increased water use of ring-porous species was attributed to (1) higher air T and (2) stomatal acclimation to VPD resulting in higher gs and more sensitive stomata...

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

    Directory of Open Access Journals (Sweden)

    Hogg Bridget V

    2011-12-01

    Full Text Available Abstract 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.

  12. The effects of plant density of Melastoma malabathricum on the erosion rate of slope soil at different slope orientations

    Institute of Scientific and Technical Information of China (English)

    Aimee Halim n; Osman Normaniza

    2015-01-01

    abstract Malaysia's cut slopes, especially for road lines accommodation, are prone to erosions and landslides. These problems mainly occur due to lack of vegetation cover and strong erosive forces. In addition, the topography factors have also become a major factor affecting soil degradation. Thus, this study is aimed at determining the effects of planting density of a selected species, namely Melastoma malabathricum;one, two, and three seedlings per box, on the erosion rate at selected slopes of different orientation (morning and evening sun) at the Guthrie Corridor Expressway, Selangor. In six months of observation, treatment with three seedlings/box on the morning sun slope showed a lower erosion rate by 69.2%than those with the same treatment on the evening sun slope. In addition, the treatment of the three seedlings recorded at month six (final observation) had the highest reduction of soil saturation level (STL), by 23.6%. Furthermore, the physiological values of the species studied, grown on the morning sun slope, were higher in terms of stomatal conductance and photosynthetic rate by 12.1%and15.8%(three seedlings/box), respectively. The overall results showed that plant density was inversely related to the STL and erosion rate on the slope. In conclusion, a planting density of three seedlings/box and morning sun orientation gave positive effects on the plant's physiological performance of the slope, reducing the STL, as well as alleviating the erosion rate of slope soils.

  13. Genetic Variation of Morphological Traits and Transpiration in an Apple Core Collection under Well-Watered Conditions: Towards the Identification of Morphotypes with High Water Use Efficiency.

    Directory of Open Access Journals (Sweden)

    Gerardo Lopez

    Full Text Available Water use efficiency (WUE is a quantitative measurement which improvement is a major issue in the context of global warming and restrictions in water availability for agriculture. In this study, we aimed at studying the variation and genetic control of WUE and the respective role of its components (plant biomass and transpiration in a perennial fruit crop. We explored an INRA apple core collection grown in a phenotyping platform to screen one-year-old scions for their accumulated biomass, transpiration and WUE under optimal growing conditions. Plant biomass was decompose into morphological components related to either growth or organ expansion. For each trait, nine mixed models were evaluated to account for the genetic effect and spatial heterogeneity inside the platform. The Best Linear Unbiased Predictors of genetic values were estimated after model selection. Mean broad-sense heritabilities were calculated from variance estimates. Heritability values indicated that biomass (0.76 and WUE (0.73 were under genetic control. This genetic control was lower in plant transpiration with an heritability of 0.54. Across the collection, biomass accounted for 70% of the WUE variability. A Hierarchical Ascendant Classification of the core collection indicated the existence of six groups of genotypes with contrasting morphology and WUE. Differences between morphotypes were interpreted as resulting from differences in the main processes responsible for plant growth: cell division leading to the generation of new organs and cell elongation leading to organ dimension. Although further studies will be necessary on mature trees with more complex architecture and multiple sinks such as fruits, this study is a first step for improving apple plant material for the use of water.

  14. Integrated rate expression for the production of glucose equivalent in C4 green plant and the effect of temperature

    Indian Academy of Sciences (India)

    Anirban Panda; Sambhu N Datta

    2007-09-01

    A temperature-dependent integrated kinetics for the overall process of photosynthesis in green plants is discussed. The C4 plants are chosen and in these plants, the rate of photosynthesis does not depend on the partial pressure of O2. Using some basic concepts like chemical equilibrium or steady state approximation, a simplified scheme is developed for both light and dark reactions. The light reaction rate per reaction center ('1) in thylakoid membrane is related to the rate of exciton transfer between chlorophyll neighbours and an expression is formulated for the light reaction rate '1. A relation between '1 and the NADPH formation rate is established. The relation takes care of the survival probability of the membrane. The CO2 saturation probability in bundle sheath is also taken into consideration. The photochemical efficiency () is expressed in terms of these probabilities. The rate of glucose production is given by glucose = (8/3)('1L)()() ([G3P]/[i]2 leaf)SSG3P → glucose where is the activity quotient of the involved enzymes, and G3P represent glycealdehyde-3-phosphate in steady state. A Gaussian distribution for temperaturedependence and a sigmoid function for de-activation are incorporated through the quotient . In general, the probabilities are given by sigmoid curves. The corresponding parameters can be easily determined. The theoretically determined temperature-dependence of photochemical efficiency and glucose production rate agree well with the experimental ones, thereby validating the formalism.

  15. On the development of turbulent boundary layer with wall transpiration

    Science.gov (United States)

    Ferro, Marco; Downs, Robert S., III; Fallenius, Bengt E. G.; Fransson, Jens H. M.

    2015-11-01

    An experimental study of the development of the transpired boundary layer in zero pressure gradient is carried out on a 6.4 m long hydrodynamically smooth and perforated plate. The relatively longer development length of the present perforated plate compared to the ones used in previous studies allows us to investigate whether an asymptotic suction boundary layer with constant thickness is achieved for the turbulent state, analogously to what happens in the laminar state. Velocity profiles are obtained via hot-wire anemometry while the wall shear stress is measured at several streamwise locations with hot-film and wall-wire probes as well as with oil-film interferometry. The threshold suction coefficient above which relaminarization starts to occur is examined. The scaling of the mean velocity and of higher order velocity moments is discussed in light of the measured wall shear stress data. Support from the European Research Council of the Advanced Fluid Research On Drag reduction in Turbulence Experiments (AFRODITE) is acknowledged.

  16. Dependence of leaf surface potential response of a plant (Ficus Elastica) to light irradiation on room temperature; Shokubutsu (gomunoki) hamen den`i no hikari shosha oto no shitsuon izonsei

    Energy Technology Data Exchange (ETDEWEB)

    Ishii, H.; Kenmoku, Y.; Sakakibara, T. [Toyohashi University of Technology, Aichi (Japan); Nakagawa, S. [Maizuru National College of Technology, Kyoto (Japan); Kawamoto, T. [Shizuoka University, Shizuoka (Japan)

    1997-11-25

    In order to clarify plant body potential information, study was made on a leaf surface potential response to light irradiation. The leaf surface potential change, total transpiration and transpiration rate of Ficus Elastica were measured using light irradiation period and room temperature as parameters. The leaf surface potential change shows a positive peak after the start of light irradiation, while a negative peak after its end. Arrival time to both peaks is constant regardless of the light irradiation period, while decrease with an increase in room temperature. Although the total transpiration increases with room temperature, this tendency disappears with an increase in light irradiation period. The transpiration rate shows its peak after the start of light irradiation. Arrival time to the peak is saturated with the light irradiation period of 60min, while decreases with an increase in room temperature. These results suggest that opening of stomata becomes active with an increase in room temperature, and the peak of the leaf surface potential after the start of light irradiation relates to the opening. 3 refs., 11 figs.

  17. Transport of root-derived CO2 via the transpiration stream affects aboveground tree physiology

    Science.gov (United States)

    Bloemen, J.; McGuire, M. A.; Aubrey, D. P.; Teskey, R. O.; Steppe, K.

    2012-04-01

    Recent research on soil CO2 efflux has shown that belowground autotrophic respiration is largely underestimated using classical net CO2 flux measurements. Aubrey & Teskey (2009) found that in forest ecosystems a substantial portion of the CO2 released from root respiration remained within the root system and was transported aboveground in the stem via the transpiration stream. The magnitude of this upward movement of CO2 from belowground tissues suggested important implications for how we measure above- and belowground respiration. If a considerable fraction of root-respired CO2 is transported aboveground, where it might be fixed in woody and leaf tissues, then we are routinely underestimating the amount of C needed to sustain belowground tissues. In this study, we infused 13C labeled water into the base of field-grown poplar trees as a surrogate for root-respired CO2 to investigate the possible role of root-derived CO2 as substrate for carbon fixation. The label was transported upwards from the base of the tree toward the top. During its ascent, the 13C label was removed from the transpiration stream and fixed by chlorophyll-containing woody (young bark and xylem) and leaf (petiole) tissues. Moreover, based on 13C analysis of gas samples, we observed that up to 88 ± 0.10 % of the label applied was lost to the atmosphere by stem and branch efflux higher in the trees. Given that one-half of root-respired CO2 may follow this internal flux pathway (Aubrey & Teskey, 2009), we calculated that up to 44% of the root-respired CO2 could diffuse to the atmosphere once transported to the stem and branches. Thus, a large portion of CO2 that diffuses out of aboveground tissues may actually result from root respiration. Our results show that CO2 originating belowground can be transported internally to aboveground parts of trees, where it will have an important impact on tree physiology. Internal transport of CO2 indicates that the gas exchange approach to estimating above- and

  18. An examination of heat rate improvements due to waste heat integration in an oxycombustion pulverized coal power plant

    Science.gov (United States)

    Charles, Joshua M.

    Oxyfuel, or oxycombustion, technology has been proposed as one carbon capture technology for coal-fired power plants. An oxycombustion plant would fire coal in an oxidizer consisting primarily of CO2, oxygen, and water vapor. Flue gas with high CO2 concentrations is produced and can be compressed for sequestration. Since this compression generates large amounts of heat, it was theorized that this heat could be utilized elsewhere in the plant. Process models of the oxycombustion boiler, steam cycle, and compressors were created in ASPEN Plus and Excel to test this hypothesis. Using these models, heat from compression stages was integrated to the flue gas recirculation heater, feedwater heaters, and to a fluidized bed coal dryer. All possible combinations of these heat sinks were examined, with improvements in coal flow rate, Qcoal, net power, and unit heat rate being noted. These improvements would help offset the large efficiency impacts inherent to oxycombustion technology.

  19. Changes in 14CO2 absorption rates by the successive leaves in buckwheat and white mustard plants of various ages

    Directory of Open Access Journals (Sweden)

    B. Gej

    2015-01-01

    Full Text Available The experiments with different-aged buckwheat (Fagopyrum esculentum Mnch. and white mustard (Sinapis alba L. plants showed that the sub-apical and middle leaves, before they had reached their approximate final sizes, had the highest rates of 14CO2 absorption. The intensity of this process decreases in each leaf with age of the plant. White mustard leaves showed a little higher absorption rate of 14CO2 than analogous leaves of buckwheat plants. In the investigated leaves no close relationship between the intensity of 14CO2 assimilation and chlorophyll a and b concentration was observed. Some possible reasons for the higher intensity of photosynthesis in the sub-apical leaves are discussed.

  20. Low-Cost and Light-Weight Transpiration-Cooled Thrust Chambers Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed effort aims to evaluate the feasibility of using transpiration-cooled Titanium as the primary material in small-scale thrust chambers for in-space...

  1. Variation of the return rate of a thermoelectric power plant; Variacao da taxa de retorno de termoeletrica

    Energy Technology Data Exchange (ETDEWEB)

    Schwyter, Anton A.; Saviano, Jose Fernando F. [Companhia de Gas de Sao Paulo, SP (Brazil); Vasconcelos, Marcio V. [ELETROPAULO, Sao Paulo, SP (Brazil); Almanca, Reinaldo A. [Companhia Energetica de Sao Paulo, SP (Brazil)

    1998-12-31

    This paper analyzes the variation of the internal rate of return of a thermoelectrical plant using natural gas, that acts as supplier, selling capacity to the electrical system, and as buyer of secondary energy, when this price is inferior as its variable costs of production. (author) 18 refs., 1 fig.

  2. Effect of Planting Methods and Seeding Rates on Yield of Alfalfa (Medicago sativa L. CV. Hamedani in Bajgah, Fars Province

    Directory of Open Access Journals (Sweden)

    A. Yazdani

    2015-06-01

    ha-1, respectively. Seeding rates also had a significant effect on number of weeds so that maximum and minimum weed numbers were obtained in 20 kg and 5 kg seed ha-1. Our results showed that 20 kg seed ha-1 and furrow planting method was the best treatment to gain maximum forage yield and minimum weed's detrimental impact.

  3. Effect of application rate and persistence of boric acid sugar baits applied to plants control of Aedes albopictus

    Science.gov (United States)

    The use of toxic baits to kill adult Aedes albopictus (Skuse) mosquitoes is a safe and potentially effective alternative to the use of synthetic chemical insecticides. This study was made to identify effective application rates for boric acid-sugar solution baits sprayed onto plant surfaces and to ...

  4. Flow rate analysis of wastewater inside reactor tanks on tofu wastewater treatment plant

    Science.gov (United States)

    Mamat; Sintawardani, N.; Astuti, J. T.; Nilawati, D.; Wulan, D. R.; Muchlis; Sriwuryandari, L.; Sembiring, T.; Jern, N. W.

    2017-03-01

    The research aimed to analyse the flow rate of the wastewater inside reactor tanks which were placed a number of bamboo cutting. The resistance of wastewater flow inside reactor tanks might not be occurred and produce biogas fuel optimally. Wastewater from eleven tofu factories was treated by multi-stages anaerobic process to reduce its organic pollutant and produce biogas. Biogas plant has six reactor tanks of which its capacity for waste water and gas dome was 18 m3 and 4.5 m3, respectively. Wastewater was pumped from collecting ponds to reactors by either serial or parallel way. Maximum pump capacity, head, and electrical motor power was 5m3/h, 50m, and 0.75HP, consecutively. Maximum pressure of biogas inside the reactor tanks was 55 mbar higher than atmosphere pressure. A number of 1,400 pieces of cutting bamboo at 50-60 mm diameter and 100 mm length were used as bacteria growth media inside each reactor tank, covering around 14,287 m2 bamboo area, and cross section area of inner reactor was 4,9 m2. In each reactor, a 6 inches PVC pipe was installed vertically as channel. When channels inside reactor were opened, flow rate of wastewater was 6x10-1 L.sec-1. Contrary, when channels were closed on the upper part, wastewater flow inside the first reactor affected and increased gas dome. Initially, wastewater flowed into each reactor by a gravity mode with head difference between the second and third reactor was 15x10-2m. However, head loss at the second reactor was equal to the third reactor by 8,422 x 10-4m. As result, wastewater flow at the second and third reactors were stagnant. To overcome the problem pump in each reactor should be installed in serial mode. In order to reach the output from the first reactor and the others would be equal, and biogas space was not filled by wastewater, therefore biogas production will be optimum.

  5. EFFECT OF DIFFERENT SOURCES AND RATES OF SOME ORGANIC MANURE ON CONTENT OF SOME HEAVY METALS IN DIFFERENT SOILS AND PLANTS GROWN THEREIN: I. EFFECT ON SPINACH PLANTS.

    Directory of Open Access Journals (Sweden)

    Hala Kandil

    2012-12-01

    Full Text Available This experiment was conducted to study the influence of different sources and rates of some organic manure on growth and heavy metals concentration in spinach plants grown on two different soils. Resultsshowed that values of dry weight (DW of roots, shoots and total plant of spinach grown on Abou-Rawash and El-Nobaria soils significantly increased by using all the organic manure sources (sewage sludge(SS, banana and cotton composts (BC and CC and rates (11, 22, and 44 t/fed as compared with control treatment. Thehighest dry weight of roots, shoots and total spinach plants grown on both soils were obtained by using cotton compost (CC followed by banana compost (BC and sewage sludge (SS in decreasing order (CC > BC > SS. The obtained results revealed that DW of spinach plants grown on sandy calcareous soil of El- Nobaria was higher under all the organic manure treatments than those obtained from sandy soil of Abou-Rawash. Moreover, dry weight of spinach plants grown on Abou-Rawash and El-Nobaria soils significantly increased by increasing the application rate from all the used organic manures up to 44 t/fed. Organic manures (SS, BC and CC led to more significantly increases in the concentration of Zn, Cu, Pb, Cd and Ni in both roots and shoots of spinach plants grown on Abou-Rawash and El-Nobaria soils as compared with control treatment. Theconcentration of Zn, Cu, Pb, Cd and Ni in roots and shoots of spinach plants grown on sandy and calcareous soils were higher when SS was applied to the tested soils in comparison with the addition of the other organic composts (BC and CC. The tested sources of organic manures could be arranged due to their inducing effect on Zn, Cu, Pb, Cd and Ni concentrations in roots and shoots of spinach plants grown on both soils in the following decreasing order: SS > CC > BC. The efficiency of studied materials on heavy metal concentrations was varied in accordance to sources and rates of application and / or the part of

  6. Influence of biochar, mycorrhizal inoculation and fertilizer rate on growth and flowering of pelargonium (Pelargonium zonale L. plants

    Directory of Open Access Journals (Sweden)

    Giulia eConversa

    2015-06-01

    Full Text Available Peat is the most common substrate used in nurseries despite being a very expensive and a non-renewable material. Peat replacement with biochar could be a sound environmental practice, as it is produced from waste biomass, but evaluation of biochar as a potting substrate is needed. Ratios of peat:biochar of 100:0, 70:30, 30:70 (BC0, BC30, and BC70, respectively, two fertilizer rates (FERT1, FERT2 and arbuscular mycorrhizal fungi (AMF inoculation were tested on potted pelargonium plants. Plant growth, flowering, bio-physiological and nutritional responses, and root mycorrhization were evaluated. The BC30 mixture did not affect plant growth compared with pure peat. However, BC30 in combination with FERT2 treatment was more effective in enhancing nitrogen (N and chlorophyll leaf concentrations, and leaf and flower numbers. The BC70 mixture depressed plant growth, flowering traits and root mycorrhization. Leaf N concentration was below the sufficiency range reported for pelargonium growth. Leaf concentration of phosphorous (P was adequate in pure peat and in BC30 but it dropped close to sub-optimal values in BC70. The pH value of the mixtures lowered P availability, though in BC30 the mycorrhizal activity could have allowed adequate P plant uptake. In BC70 plants, the deficiency of both N and P might be a reason for the observed growth reduction. The inoculation of the substrate with selected AMF improved plant growth (higher dry biomass, greater floral clusters, larger and more abundant leaves and quality resulting in unstressed (lower electrolyte leakage and higher relative water content values and greener leaves (low L* and C*, high chlorophyll content and in more intensely colored flowers. We conclude that biochar can be applied in nursery/potted plant production provided that the proportion in the peat mixture does not exceed 30%. Furthermore, AMF inoculation contributed to achieving the best plant performance in 30% biochar amended medium.

  7. Solution aluminum and transpiration in Picea rubens and Gleditsia triacanthos seedlings.

    Science.gov (United States)

    Ren, Z; Sucoff, E I

    1990-09-01

    Soil solution Al may contribute to red spruce (Picea rubens Sarg.) decline by inhibiting transpiration (Klein 1985). This study examines how Al affects transpiration in red spruce and honeylocust (Gleditsia triacanthos L.) seedlings and explores mechanisms for the observed responses. Red spruce seedlings were grown in dilute nutrient solutions containing 0 to 925 microM Al at pH 4.5 or 3.8. Solution Al had no effect on the transpiration, root hydraulic conductivity (K(r)) or shoot water potential (Psi) of red spruce. Transpiration of honeylocust was higher in the presence of 100 to 350 microM Al than 0, 500, or 600 microM Al. The Al-induced increases in transpiration of honeylocust were unrelated to shoot Psi or root K(r), but were closely correlated with the greater root lengths produced by intermediate levels of Al. In neither species was transpiration correlated with tissue concentrations of Al, P, K, Ca or Mg.

  8. Soil water and transpirable soil water fraction variability within vineyards of the Penedès DO (NE Spain) affected by management practices

    Science.gov (United States)

    Concepción Ramos, Maria

    2015-04-01

    This work investigated the variability in soil water recorded within the vineyard plots related to soil properties and management practices and its influence on the transpirable sol water fraction. The study was carried out in vineyards in the Penedès Designation of Origin, planted with Chardonnay, with different disturbance degree and with compost treated and untreated areas within the plots. The response in years with different rainfall distributions, included years with extreme situations were evaluated. The main soil types are Typic Xerorthent and Calcixerollic Xerorthent and soil is bare most of the time. Soil water content was measured at different depths using TDR probes. The transpirable soil water fraction was estimated as the ratio between available soil water (ASW) at a given date and the total transpirable soil water (TTSW). TTSW was estimated as the soil water reserve held between an upper and lower limit (respectively, the soil water content near field capacity and soil water content at the end of a dry summer) and integrated over the estimated effective rooting depth. Both minimum and maximum soil water values varied within the plot at all depths. On the surface the minimum values ranged between 4.45 to about 10%, while on deeper layers it ranged between 7.8 and 17.8%. Regarding the maximum value varied between 17.45 and 24.8%. The transpirable soil water fraction for a given year varied significantly within the plot, with differences greater than 20% between the treated and untreated areas. The results were more exacerbated in the driest years an in those with more irregular distribution. Water available has a significant effect on yield. The results indicate the need of using different strategies for water management within the plots.

  9. Mycorrhizal and non-mycorrhizal Lactuca sativa plants exhibit contrasting responses to exogenous ABA during drought stress and recovery

    Science.gov (United States)

    Aroca, Ricardo; Vernieri, Paolo; Ruiz-Lozano, Juan Manuel

    2008-01-01

    The arbuscular mycorrhizal (AM) symbiosis enhances plant tolerance to water deficit through the alteration of plant physiology and the expression of plant genes. These changes have been postulated to be caused (among others) by different contents of abscisic acid (ABA) between AM and non-AM plants. However, there are no studies dealing with the effects of exogenous ABA on the expression of stress-related genes and on the physiology of AM plants. The aim of the present study was to evaluate the influence of AM symbiosis and exogenous ABA application on plant development, physiology, and expression of several stress-related genes after both drought and a recovery period. Results show that the application of exogenous ABA had contrasting effects on AM and non-AM plants. Only AM plants fed with exogenous ABA maintained shoot biomass production unaltered by drought stress. The addition of exogenous ABA enhanced considerably the ABA content in shoots of non-AM plants, concomitantly with the expression of the stress marker genes Lsp5cs and Lslea and the gene Lsnced. By contrast, the addition of exogenous ABA decreased the content of ABA in shoots of AM plants and did not produce any further enhancement of the expression of these three genes. AM plants always exhibited higher values of root hydraulic conductivity and reduced transpiration rate under drought stress. From plants subjected to drought, only the AM plants recovered their root hydraulic conductivity completely after the 3 d recovery period. As a whole, the results indicate that AM plants regulate their ABA levels better and faster than non-AM plants, allowing a more adequate balance between leaf transpiration and root water movement during drought and recovery. PMID:18469324

  10. Modeling Plant Uptake of Metal in Constructed Wetlands Supported by Experimentally Derived Uptake Rates.

    Science.gov (United States)

    1996-12-01

    stress to a system and could eventually induce chronic effects such as decreased species diversity and biomass , altered biogeochemical nutrient...erosion Remove accumulated solids in forebay and near outlet Clean pretreatment devices; clean forebay once every five years or when sediment exceeds...Sagua la Grande river basin near a chlor- alkali plant and other industrial plants differed by location. Highest concentrations were found in the zone

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

    Science.gov (United States)

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

    1986-01-01

    This study reports on the effects of nitrogen stress and restoration of nitrogen availability after a period of stress on expansion and photosynthetic rate of soybean leaves of differing maturity. We hypothesized that nitrogen resupply would lead to additional accumulation of reduced nitrogen in the leaves and, ultimately, resumption of leaf initiation and expansion and photosynthetic activity. In continuously nitrogen-stressed plants, expansion of middle trifoliolates of main-stem trifoliates and leaf area at full expansion were severely restricted. Leaves showing the greatest effects were initiated after removal of nitrogen. When the reduced nitrogen concentration in mature leaves of continuously stressed plants fell below 9 mg dm-2, the photosynthetic rate per unit leaf decreased rapidly, reaching a minimum of ca. 6-8 mg dm-2 h-1. The older mature leaves tended to abscise at this point, while the youngest leaves remained on the plant and continued to photosynthesize slowly. When nitrogen was resupplied, leaf expansion and final leaf area increased. Leaf initiation was also stimulated as reduced nitrogen levels rose in the leaves. Photosynthetic rates of the oldest and youngest pair of mature leaves returned to values comparable to those of similar-aged leaves of nonstressed soybean plants.

  12. Relationships between xylem embolism and eco-physiological indices in eight woody plants in sltu(Ⅱ):The relationship with photosynthetic eco-physiological indices

    Institute of Scientific and Technical Information of China (English)

    AN Feng; CAI Jing; JIANG Zaimin; ZHANG Yuanying; ZHAO Pingjuan; ZHANG Shuoxin

    2007-01-01

    The relationship between xylem embolism and eco-physiology indices (I.e.photosynthetic available radiation,temperature,relative humidity,photosynthetic rate,transpiration rate,stomatal conductance and water use efficiency) in eight tree species was investigated in situ.The species studied,Robinia pseudoacacia L.,Acer truncatum Bge.,Hippophae rhamnoides L.,Ulmus pumila L.,Pinus tabulaeformis Carr., Pinus bungeana Zucc.ex Endl.,Ligustrum lucidum Ait.,and Salix matsudana Koidz.f.pendula Schneid,grow well on the Xilin campus of Northwest A&F University.Results indicated that photosynthetic available radiation,air temperature and relative humidity can affect xylem embolism by daily adjustment of stomatal conductance,transpiration rate and water relations of a tree.Embolism was a common case in the daily growth of the plants,and there was some correlation between xylem embolism and photosynthetic rate,transpiration rate,stornatal conductance,and water use efficiency.Embolism may thus be an adaptive mechanism by some tree species to water stress.

  13. Differences in Copper Absorption and Accumulation between Copper-Exclusion and Copper-Enrichment Plants: A Comparison of Structure and Physiological Responses.

    Science.gov (United States)

    Fu, Lei; Chen, Chen; Wang, Bin; Zhou, Xishi; Li, Shuhuan; Guo, Pan; Shen, Zhenguo; Wang, Guiping; Chen, Yahua

    2015-01-01

    Differences in copper (Cu) absorption and transport, physiological responses and structural characteristics between two types of Cu-resistant plants, Oenothera glazioviana (Cu-exclusion type) and Elsholtzia haichowensis (Cu-enrichment type), were investigated in the present study. The results indicated the following: (1) After 50 μM Cu treatment, the Cu ratio in the xylem vessels of E. haichowensis increased by 60%. A Cu adsorption experiment indicated that O. glazioviana exhibited greater resistance to Cu, and Cu absorption and the shoot/root ratio of Cu were significantly lower in O. glazioviana than in E. haichowensis. (2) An analysis of the endogenous abscisic acid (ABA) variance and exogenous ABA treatment demonstrated that the ABA levels of both plants did not differ; exogenous ABA treatment clearly reduced Cu accumulation in both plants. (3) The leaf stomatal density of O. glazioviana was significantly less than that of E. haichowensis. Guard cells in E. haichowensis plants were covered with a thick cuticle layer, the epidermal hair was more numerous and longer, and the number of xylem conduits in the root was small. (4) The transpiration rate and the stomatal conductance of O. glazioviana were both significantly lower than those of E. haichowensis, regardless of whether the plants were treated with Cu. Taken together, these results indicate that the differences in the structural characteristics between these two plant species, particularly in the characteristics related to plant transpiration, are important factors that govern whether plants acquire or exclude Cu.

  14. Differences in Copper Absorption and Accumulation between Copper-Exclusion and Copper-Enrichment Plants: A Comparison of Structure and Physiological Responses.

    Directory of Open Access Journals (Sweden)

    Lei Fu

    Full Text Available Differences in copper (Cu absorption and transport, physiological responses and structural characteristics between two types of Cu-resistant plants, Oenothera glazioviana (Cu-exclusion type and Elsholtzia haichowensis (Cu-enrichment type, were investigated in the present study. The results indicated the following: (1 After 50 μM Cu treatment, the Cu ratio in the xylem vessels of E. haichowensis increased by 60%. A Cu adsorption experiment indicated that O. glazioviana exhibited greater resistance to Cu, and Cu absorption and the shoot/root ratio of Cu were significantly lower in O. glazioviana than in E. haichowensis. (2 An analysis of the endogenous abscisic acid (ABA variance and exogenous ABA treatment demonstrated that the ABA levels of both plants did not differ; exogenous ABA treatment clearly reduced Cu accumulation in both plants. (3 The leaf stomatal density of O. glazioviana was significantly less than that of E. haichowensis. Guard cells in E. haichowensis plants were covered with a thick cuticle layer, the epidermal hair was more numerous and longer, and the number of xylem conduits in the root was small. (4 The transpiration rate and the stomatal conductance of O. glazioviana were both significantly lower than those of E. haichowensis, regardless of whether the plants were treated with Cu. Taken together, these results indicate that the differences in the structural characteristics between these two plant species, particularly in the characteristics related to plant transpiration, are important factors that govern whether plants acquire or exclude Cu.

  15. Transcriptomics and molecular evolutionary rate analysis of the bladderwort (Utricularia, a carnivorous plant with a minimal genome

    Directory of Open Access Journals (Sweden)

    Herrera-Estrella Alfredo

    2011-06-01

    Full Text Available Abstract Background The carnivorous plant Utricularia gibba (bladderwort is remarkable in having a minute genome, which at ca. 80 megabases is approximately half that of Arabidopsis. Bladderworts show an incredible diversity of forms surrounding a defined theme: tiny, bladder-like suction traps on terrestrial, epiphytic, or aquatic plants with a diversity of unusual vegetative forms. Utricularia plants, which are rootless, are also anomalous in physiological features (respiration and carbon distribution, and highly enhanced molecular evolutionary rates in chloroplast, mitochondrial and nuclear ribosomal sequences. Despite great interest in the genus, no genomic resources exist for Utricularia, and the substitution rate increase has received limited study. Results Here we describe the sequencing and analysis of the Utricularia gibba transcriptome. Three different organs were surveyed, the traps, the vegetative shoot bodies, and the inflorescence stems. We also examined the bladderwort transcriptome under diverse stress conditions. We detail aspects of functional classification, tissue similarity, nitrogen and phosphorus metabolism, respiration, DNA repair, and detoxification of reactive oxygen species (ROS. Long contigs of plastid and mitochondrial genomes, as well as sequences for 100 individual nuclear genes, were compared with those of other plants to better establish information on molecular evolutionary rates. Conclusion The Utricularia transcriptome provides a detailed genomic window into processes occurring in a carnivorous plant. It contains a deep representation of the complex metabolic pathways that characterize a putative minimal plant genome, permitting its use as a source of genomic information to explore the structural, functional, and evolutionary diversity of the genus. Vegetative shoots and traps are the most similar organs by functional classification of their transcriptome, the traps expressing hydrolytic enzymes for prey

  16. Representing plant hydraulics in a global Earth system model.

    Science.gov (United States)

    Kennedy, D.; Gentine, P.

    2015-12-01

    Earth system models need improvement to reproduce observed seasonal and diurnal cycles of photosynthesis and respiration. Model water stress parameterizations lag behind the plant physiology literature. A plant hydraulics model is developed and deployed in a global Earth system model (NCAR CESM 1.2.2 with CLM 4.5). Assimilation and transpiration are attenuated according to literature cavitation curves. Water stress is evaluated based on plant functional type hydraulic parameters forced by soil moisture and atmospheric conditions. Resolving the plant water status allows for modelling divergent strategies for water stress. The case of isohydric versus anisohydric species is presented, showing that including plant hydraulic traits alter modelled photosynthesis and transpiration.

  17. Effect of application rate and persistence of boric acid sugar baits applied to plants for control of Aedes albopictus.

    Science.gov (United States)

    Xue, Rui-De; Müller, Günter C; Kline, Daniel L; Barnard, Donald R

    2011-03-01

    The use of toxic bait to kill adult Aedes albopictus is a safe and potentially effective alternative to the use of synthetic chemical insecticides. This study was carried out to determine effective concentrations of boric acid needed in sugar bait solutions applied to plant surfaces, and to determine its residual effect in reducing adult mosquito densities. In outdoor tests in 1,100-m3 screened enclosures, landing rates of Ae. albopictus on a human subject and the number of female mosquitoes in mechanical traps were significantly reduced by a 1% boric acid bait compared with the other tested concentrations (0.25%, 0.50%, and 0.75%) and untreated control. Studies of the duration of boric acid activity on plant surfaces were made in 1.4-m3 cages in the laboratory and outdoors in 78-m3 screened enclosures. In the laboratory tests, 1% boric acid bait resulted in >96% mortality in male and female Ae. albopictus for 14 days, whereas in outdoor tests, mosquito landing rates in the treated enclosures were significantly lower than in the control enclosures for 7 days. Also, mosquito mortality responses to boric acid baits between plants with flowers and nonflowers (1.4-m3 cages in the laboratory) were not significantly different. The results of this study suggest that boric acid baits applied to plant surfaces may provide specific data related to the development of an effective point-source-based adjunct/alternative to the use of conventional adulticides for mosquito control.

  18. Partition of nocturnal sap flow in Acacia mangium and its implication for estimating the whole-tree transpiration

    Institute of Scientific and Technical Information of China (English)

    Hua WANG; Ping ZHAO; Xian CAI; Ling MA; Xingquan RAO; Xiaoping ZENG; Quan WANG

    2009-01-01

    We analyzed the partition of nocturnal sap flow into refilling of internal water storage and transpiration in Acacia mangium. Sap flow of trees was monitored continuously with Granier's sensors for estimating the whole-tree transpiration. Possible night transpiration and stomatal conductance at the leaf level in the canopy were measured with a LI-6400 photosynthesis measuring system. For nocturnal leaf transpiration and stomatal conductance were weak, nocturnal sap flow of mature A. mangium trees was mainly associated with water recharge in the trunk. No significant change in night water recharge of the trunk was found at both seasonal and inter-annual scales. Morphological features of trees including diameter at the breast height (DBH), tree height, and canopy size could explain variances of night water recharge. Furthermore, although the contribution of nocturnal sap flow to the total transpiration varied among seasons and DBH classes, the error caused by night water recharge on whole-tree transpiration was negligible.

  19. Anaerobic soil disinfestation: Carbon rate effects on tomato plant growth and organic acid production

    Science.gov (United States)

    Anaerobic soil disinfestation (ASD) is a non-chemical soil disinfestation technique proposed for the control of soil-borne pathogens, plant parasitic-nematodes, and weeds in different crops. ASD is applied in three steps: 1) Soil amendment with a labile carbon (C) source; 2) Cover the soil with tota...

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

    Science.gov (United States)

    Bergtold, Matthias; Dohmen, Gerhard Peter

    2011-04-01

    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. Copyright © 2010 SETAC.

  1. Transpiration flow controls Zn transport in Brassica napus and Lolium multiflorum under toxic levels as evidenced from isotopic fractionation

    Science.gov (United States)

    Couder, Eléonore; Mattielli, Nadine; Drouet, Thomas; Smolders, Erik; Delvaux, Bruno; Iserentant, Anne; Meeus, Coralie; Maerschalk, Claude; Opfergelt, Sophie; Houben, David

    2015-11-01

    Stable zinc (Zn) isotope fractionation between soil and plant has been used to suggest the mechanisms affecting Zn uptake under toxic conditions. Here, changes in Zn isotope composition in soil, soil solution, root and shoot were studied for ryegrass (Lolium multiflorum L.) and rape (Brassica napus L.) grown on three distinct metal-contaminated soils collected near Zn smelters (total Zn 0.7-7.5%, pH 4.8-7.3). The Zn concentrations in plants reflected a toxic Zn supply. The Zn isotopic fingerprint of total soil Zn varied from -0.05‰ to +0.26 ± 0.02‰ (δ66Zn values relative to the JMC 3-0749L standard) among soils, but the soil solution Zn was depleted in 66Zn, with a constant Zn isotope fractionation of about -0.1‰ δ66Zn unit compared to the bulk soil. Roots were enriched with 66Zn relative to soil solution (δ66Znroot - δ66Znsoil solution = Δ66Znroot-soil solution = +0.05 to +0.2 ‰) and shoots were strongly depleted in 66Zn relative to roots (Δ66Znshoot-root = -0.40 to -0.04 ‰). The overall δ66Zn values in shoots reflected that of the bulk soil, but were lowered by 0.1-0.3 ‰ units as compared to the latter. The isotope fractionation between root and shoot exhibited a markedly strong negative correlation (R2 = 0.83) with transpiration per unit of plant weight. Thus, the enrichment with light Zn isotopes in shoot progressed with increasing water flux per unit plant biomass dry weight, showing a passive mode of Zn transport by transpiration. Besides, the light isotope enrichment in shoots compared to roots was larger for rape than for rye grass, which may be related to the higher Zn retention in rape roots. This in turn may be related to the higher cation exchange capacity of rape roots. Our finding can be of use to trace the biogeochemical cycles of Zn and evidence the tolerance strategies developed by plants in Zn-excess conditions.

  2. Leaf water relations and sapflow in eastern cottonwood (Populus deltoides Bartr.) trees planted for phytoremediation of a groundwater pollutant

    Science.gov (United States)

    James M. Vose; Wayne T. Swank; Gregory J. Harvey; Barton D. Clinton; Christine Sobek

    2000-01-01

    Plants that remediate groundwater pollutants may offer a feasible alternative to the traditional and more expensive practices. Because its success depends on water use, this approach requires a complete understanding of species-specific transpiration patterns. The objectives of this study were (1) to quantify tree and stand-level transpiration in two age classes (whips...

  3. EFFECT OF DIFFERENT SOURCES AND RATES OF SOME ORGANIC MANURE ON CONTENT OF SOME HEAVY METALS IN DIFFERENT SOILS AND PLANTS GROWN THEREIN: II. EFFECT ON CORN PLANTS

    Directory of Open Access Journals (Sweden)

    Hala Kandil

    2012-12-01

    Full Text Available This experiment was conducted to study the influence of different sources and rates of some organic manure on growth and heavy metals concentration in spinach plants grown on two different soils. The important results could be summarized in the following: results show that values of dry weight (DW of roots, shoots and total plant of corn grown on Abou-Rawash and El-Nobaria soils significantly increased by using all the organic manure sources (sewage sludge(SS, banana and cotton composts (BC and CC and rates (11, 22, and 44 t/fed as compared with control treatment. There is no significant effect between all the used organic manures (SS, BC, and CC on dry weight production of roots, shoots and total plant of corn grown on Abou-Rawash sandy soil, but in El-Nobaria sandy calcareous soil, the SS and BC treatments significantly increased dry weight of roots, shoots and total plant of corn in comparison with those obtained by using CC treatment. Furthermore, there is no any significant effect between sewage sludge (SS and (BC on the production of the dry weight of different organs of corn plant grown on El-Nobaria soil. Dry weight of corn plants grown on both soils significantly increased by increasing the application rate from all the used organic manures up to 44 t/fed. The highest DW of corn plants grown on both soils were obtained by using BC and rate of 44 t/fed, while the lowest values were attained by using CC and rate of 11 t/fed. All the organic manures (SS, BC and CC led to more significantly increases in the concentration of Zn, Cu, Pb,Cd and Ni in both roots and shoots of corn plants grown on both soils as compared with control. The concentrations of Zn, Cu, Pb, Cd and Ni in corn plants grown on Abou-Rawash significantly increased when BC was applied as compared with CC. Moreover, there is no clear difference could be found between BC and CC used in sandy calcareous soil of El-Nobaria, and the concentration of all the heavy metals in corn

  4. Plant virus infections control stomatal development

    Science.gov (United States)

    Murray, Rose R.; Emblow, Mark S. M.; Hetherington, Alistair M.; Foster, Gary D.

    2016-01-01

    Stomata are important regulators of carbon dioxide uptake and transpirational water loss. They also represent points of vulnerability as bacterial and fungal pathogens utilise this natural opening as an entry portal, and thus have an increasingly complex relationship. Unlike the situation with bacterial and fungal pathogens, we know very little about the role of stomata in viral infection. Here we report findings showing that viral infection influences stomatal development in two susceptible host systems (Nicotiana tabacum with TMV (Tobacco mosaic virus), and Arabidopsis thaliana with TVCV (Turnip vein-clearing virus)), but not in resistant host systems (Nicotiana glutinosa and Chenopodium quinoa with TMV). Virus infected plants had significantly lower stomatal indices in systemic leaves of susceptible systems; N. tabacum 9.8% reduction and A. thaliana 12.3% reduction, but not in the resistant hosts. Stomatal density in systemic leaves was also significantly reduced in virus infected A. thaliana by 19.6% but not in N. tabacum or the resistant systems. In addition, transpiration rate was significantly reduced in TMV infected N. tabacum. PMID:27687773

  5. Plant virus infections control stomatal development

    Science.gov (United States)

    Murray, Rose R.; Emblow, Mark S. M.; Hetherington, Alistair M.; Foster, Gary D.

    2016-09-01

    Stomata are important regulators of carbon dioxide uptake and transpirational water loss. They also represent points of vulnerability as bacterial and fungal pathogens utilise this natural opening as an entry portal, and thus have an increasingly complex relationship. Unlike the situation with bacterial and fungal pathogens, we know very little about the role of stomata in viral infection. Here we report findings showing that viral infection influences stomatal development in two susceptible host systems (Nicotiana tabacum with TMV (Tobacco mosaic virus), and Arabidopsis thaliana with TVCV (Turnip vein-clearing virus)), but not in resistant host systems (Nicotiana glutinosa and Chenopodium quinoa with TMV). Virus infected plants had significantly lower stomatal indices in systemic leaves of susceptible systems; N. tabacum 9.8% reduction and A. thaliana 12.3% reduction, but not in the resistant hosts. Stomatal density in systemic leaves was also significantly reduced in virus infected A. thaliana by 19.6% but not in N. tabacum or the resistant systems. In addition, transpiration rate was significantly reduced in TMV infected N. tabacum.

  6. The effect of water availability on stand-level productivity, transpiration, water use efficiency and radiation use efficiency of field-grown willow clones

    Energy Technology Data Exchange (ETDEWEB)

    Linderson, Maj-Lena [Lund University, Lund (Sweden). Geobiosphere Science Centre, Department of Physical Geography and Ecosystems Analysis; Technical University of Denmark, Roskilde (Denmark). Risoe National Laboratory, Bio Systems Department; Iritz, Zinaida [Swedish International Development Cooperation Agency, Stockholm (Sweden); Lindroth, Anders [Lund University, Lund (Sweden). Geobiosphere Science Centre, Department of Physical Geography and Ecosystems Analysis

    2007-07-15

    The effect of water availability on stand-level productivity, transpiration, water use efficiency (WUE) and radiation use efficiency (RUE) is evaluated for different willow clones at stand level. The measurements were made during the growing season 2000 in a 3-year-old plantation in Scania, southernmost Sweden. Six willow clones were included in the study: L78183, SW Rapp, SW Jorunn, SW Jorr, SW Tora and SW Loden. All clones were exposed to two water treatments: rain-fed, non-irrigated treatment and reduced water availability by reduced soil water recharge. Field measurements of stem sap-flow and biometry are up-scaled to stand transpiration and stand dry substance production and used to assess WUE. RUE is estimated from the ratio between the stand dry substance production and the accumulated absorbed photosynthetic active radiation over the growing season. The total stand transpiration rate for the 5 months lies between 100 and 325 mm, which is fairly low compared to the Penman-Monteith transpiration for willow, reaching 400-450 mm for the same period. Mean WUE of all clones and treatments is 5.3 g/kg, which is high compared to earlier studies, while average RUE is 0.31 g/mol, which is slightly low compared to other results. Generally, all clones, except for Jorunn, seem to be better off concerning biomass production, WUE and RUE than the reference clone. Jorr, Jorunn and Loden also seem to be able to cope with the reduced water availability with increase in the water use efficiency. Tora performs significantly better than the other clones concerning both growth and efficiency in light and water use, but the effect of the dry treatment on stem growth shows sensitivity to water availability. The reduced stem growth could be due to a change in allocation patterns. (author)

  7. Study on the Photosynthetic and Transpiration Characteristics of Two Succulents in Indoor Environment%2种多肉植物在室内环境中的光合及蒸腾特性研究

    Institute of Scientific and Technical Information of China (English)

    岳莉然; 岳桦

    2012-01-01

    [Objective] To study the photosynthetic and transpiration characteristics of two succulents (Kalanchoe bhssfeldiana * Sensation' and Aptenia cordifolia in indoor environment, so as to provide theoretical basis for their application in indoor decoration, [ Method] Through a continual study of indoor light intensity, temperature and humidity, a curve map about the change of indoor light was drawn. At the same time, five representative indoor environments with different light intensities were selected as the experimental area, and then a LI-6400 portable pholosynthetie system tester was used to detect the diurnal variation of C02 net absorption rate and transpiration rate, and carbon capacity and transpiration water release were measured. [ Result ] The diurnal variation of CO2 net absorption rate and transpiration rate in the two plants was basically the same in different light environment. In consideration of CO2, it is appropriate to put the two plants in a 1 052 - 1 360 jxmol/(m2 · S) light environment in the southward house, and put Kalanchoe bbssfeldiana l Sensation' by the north window and the Aptenia cordifolia by the east window of the northward house. In view of reducing air humidity, both plants should be put in a 1 052 - 1 360 jjunoJ/(m · S) light environment in the southward house, while by the north window of northward house, the transpiration amount of Kalan-ckoe bhssfeldiana 'Sensation' put at the north window of northward house was more than thai put at the window of southward house. [Conclusion] Tlie study provided references for the better application of (Kalanchoe blossfeldiana ' Sensation' and Aptenia cordifolia in indoor decoration.%[目的]研究多肉植物长寿花(Kalanchoe blossfeldiana ‘Sensation')和花蔓草(Aptenia cordifolia)在室内环境中的光合特性和蒸腾特性,为其室内应用提供理论依据.[方法]以观赏性好、市场拥有率高的多肉植物长寿花和花蔓草为试验材料,通过对室内不同环境

  8. Maize response to elevated plant density combined with lowered N-fertilizer rate is genotype-dependent

    Institute of Scientific and Technical Information of China (English)

    Ahmed; Medhat; M.Al-Naggar; Reda; A.Shabana; Mohamed; M.M.Atta; Tarek; H.Al-Khalil

    2015-01-01

    Increasing plant density and improving N fertilizer rate along with the use of high density-tolerant genotypes would lead to maximizing maize(Zea mays L.) grain productivity per unit land area. The objective of this investigation was to match the functions of optimum plant density and adequate nitrogen fertilizer application to produce the highest possible yields per unit area with the greatest maize genotype efficiency. Six maize inbred lines differing in tolerance to low N and high density(D) [three tolerant(T); L-17, L-18, L-53,and three sensitive(S); L-29, L-54, L-55] were chosen for diallel crosses. Parents and crosses were evaluated in the 2012 and 2013 seasons under three plant densities: low(47,600),medium(71,400), and high(95,200) plants ha-1and three N fertilization rates: low(no N addition), medium(285 kg N ha-1) and high(570 kg N ha-1). The T × T crosses were superior to the S × S and T × S crosses under the low N–high D environment in most studied traits across seasons. The relationships between the nine environments and grain yield per hectare(GYPH) showed near-linear regression functions for inbreds L54, L29, and L55 and hybrids L18 × L53 and L18 × L55 with the highest GYPH at a density of47,600 plants ha-1and N rate of 570 kg N ha-1and a curvilinear relationship for inbreds L17, L18, and L53 and the rest of the hybrids with the highest GYPH at a density of95,200 plants ha-1combined with an N rate of 570 kg N ha-1. Cross L17 × L54 gave the highest grain yield in this study under both high N–high-D(19.9 t ha-1) and medium N–high-D environments(17.6 t ha-1).

  9. Is whole-plant photosynthetic rate proportional to leaf area? A test of scalings and a logistic equation by leaf demography census.

    OpenAIRE

    Koyama, Kohei; Kikuzawa, Kihachiro; 小山, 耕平

    2009-01-01

    Allometric scalings and a logistic equation assume that whole-plant photosynthetic rate under resource-unlimited conditions is proportional to leaf area. We tested this proportionality for the herb Helianthus tuberosus. During growth, we repeatedly measured the percentage of leaves with high, medium, and low photosynthetic capacity to estimate the whole-plant sum of photosynthetic capacity. We found that the whole-plant sum of the light-saturated photosynthetic rate of leaves is proportional ...

  10. Increase of Power Rates Has a Big Impact on Aluminum Plants

    Institute of Scientific and Technical Information of China (English)

    2004-01-01

    <正> An important cause for the recent adjustment ofpower rates in China is to contain the growth ofhigh-energy-consumption industries by impos-ing differentiated power rates.Therefore,as thefirst of six high-energy-consumption industries,the primary aluminum industry has receivedspecial attention.Based on the complicatedplan on adjustment of power rates currentlyavailable,it is expected that approximately800,000 tons of self-baking pot production ca-

  11. Plant-specific volatile organic compound emission rates from young and mature leaves of Mediterranean vegetation

    Science.gov (United States)

    Bracho-Nunez, Araceli; Welter, Saskia; Staudt, Michael; Kesselmeier, Jürgen

    2011-08-01

    The seasonality of vegetation, i.e., developmental stages and phenological processes, affects the emission of volatile organic compounds (VOCs). Despite the potential significance, the contributions of seasonality to VOC emission quality and quantity are not well understood and are therefore often ignored in emission simulations. We investigated the VOC emission patterns of young and mature leaves of several Mediterranean plant species in relation to their physiological and developmental changes during the growing period and estimated Es. Foliar emissions of isoprenoids and oxygenated VOCs like methanol and acetone were measured online by means of a proton transfer reaction mass spectrometer (PTR-MS) and offline with gas chromatography coupled with a mass spectrometer and flame ionization detector. The results suggest that VOC emission is a developmentally regulated process and that quantitative and qualitative variability is plant species specific. Leaf ontogeny clearly influenced both the VOC Es and the relative importance of different VOCs. Methanol was the major compound contributing to the sum of target VOC emissions in young leaves (11.8 ± 10.4 μg g-1 h-1), while its contribution was minor in mature leaves (4.1 ± 4.1 μg g-1 h-1). Several plant species showed a decrease or complete subsidence of monoterpene, sesquiterpene, and acetone emissions upon maturity, perhaps indicating a potential response to the higher defense demands of young emerging leaves.

  12. Is Mass-based Metabolism Rate Proportional to Surface Area in Plant Leaves? A Data Re-analysis

    Institute of Scientific and Technical Information of China (English)

    Dongmei Jin; Yiqiang Dai; Li Sun; Shucun Sun

    2008-01-01

    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, Amass, and mass-based dark respiration, Rdmass) 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 Amass and SLA, significantly larger than 1.0; and 1.04 between Rdmass and SLA. The scaling exponent of the relationship between Amass 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 Rdmass 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.

  13. Reduction of transpiration and altered nutrient allocation contribute to nutrient decline of crops grown in elevated CO(2) concentrations.

    Science.gov (United States)

    McGrath, Justin M; Lobell, David B

    2013-03-01

    Plants grown in elevated [CO(2) ] have lower protein and mineral concentrations compared with plants grown in ambient [CO(2) ]. Dilution by enhanced production of carbohydrates is a likely cause, but it cannot explain all of the reductions. Two proposed, but untested, hypotheses are that (1) reduced canopy transpiration reduces mass flow of nutrients to the roots thus reducing nutrient uptake and (2) changes in metabolite or enzyme concentrations caused by physiological changes alter requirements for minerals as protein cofactors or in other organic complexes, shifting allocation between tissues and possibly altering uptake. Here, we use the meta-analysis of previous studies in crops to test these hypotheses. Nutrients acquired mostly by mass flow were decreased significantly more by elevated [CO(2) ] than nutrients acquired by diffusion to the roots through the soil, supporting the first hypothesis. Similarly, Mg showed large concentration declines in leaves and wheat stems, but smaller decreases in other tissues. Because chlorophyll requires a large fraction of total plant Mg, and chlorophyll concentration is reduced by growth in elevated [CO(2) ], this supports the second hypothesis. Understanding these mechanisms may guide efforts to improve nutrient content, and allow modeling of nutrient changes and health impacts under future climate change scenarios.

  14. Thermal transpiration and mechanocaloric effect. IV. Flow of a polyatomic gas in a cylindrical tube

    Science.gov (United States)

    Loyalka, S. K.; Storvick, T. S.; Lo, S. S.

    1982-04-01

    The phenomenological coefficients for mass and energy flows due to axial pressure and to temperature gradients on long capillary tubes containing a polyatomic gas at all degrees of rarefaction are reported. The Hansen and Morse polyatomic gas model of the linearized Wang Chang and Uhlenbeck equation was used together with Maxwell's diffuse scattering boundary conditions. The results are consistent with previous results obtained for flow between parallel plates. Experimental isothermal flow data are nearly quantitatively represented by the theory in the transition flow regime (Knudsen number ˜ 1). Experimental thermal transpiration effect ratios (Δp/p0)/(ΔT/T0) are also quantitatively represented for simple gases, argon, air, and carbon dioxide. Thermal transpiration measurements on sulfur dioxide correlate as the other gases but the transpiration effect ratio is not quantitatively given by the theory due to inadequacy of the Hansen-Morse model and the continuum theory for strongly polar gases.

  15. In-Containment Signal Conditioning and Transmission via Power Lines within High Dose Rate Areas of Nuclear Power Plants

    Energy Technology Data Exchange (ETDEWEB)

    Mueller, Steffen; Weigel, Robert; Koelpin, Alexander [Institute for Electronics Engineering, University of Erlangen-Nuremberg, Cauerstr. 9, 91058 Erlangen (Germany); Dennerlein, Juergen; Janke, Iryna; Weber, Johannes [AREVA GmbH, Paul-Gossen-Str. 100, 91052 Erlangen (Germany)

    2015-07-01

    Signal conditioning and transmission for sensor systems and networks within the containment of nuclear power plants (NPPs) still poses a challenge to engineers, particularly in the case of equipment upgrades for existing plants, temporary measurements, decommissioning of plants, but also for new builds. This paper presents an innovative method for efficient and cost-effective instrumentation within high dose rate areas inside the containment. A transmitter-receiver topology is proposed that allows simultaneous, unidirectional point-to-point transmission of multiple sensor signals by superimposing them on existing AC or DC power supply cables using power line communication (PLC) technology. Thereby the need for costly installation of additional cables and containment penetrations is eliminated. Based on commercial off-the-shelf (COTS) electronic parts, a radiation hard transmitter is designed to operate in harsh environment within the containment during full plant operation. Hardware modularity of the transmitter allows application specific tradeoffs between redundancy and channel bandwidth. At receiver side in non-radiated areas, signals are extracted from the power line, demodulated, and provided either in analog or digital output format. Laboratory qualification tests and field test results within a boiling water reactor (BWR) are validating the proof of concept of the proposed system. (authors)

  16. Experimental infection of Fusarium proliferatum in Oryza sativa plants; fumonisin B1 production and survival rate in grains.

    Science.gov (United States)

    Kushiro, Masayo; Saitoh, Hatsuo; Sugiura, Yoshitsugu; Aoki, Takayuki; Kawamoto, Shin-ichi; Sato, Toyozo

    2012-06-01

    Fusarium proliferatum is a plant pathogenic fungus associated with crops such as asparagus and corn, and it possesses the ability to produce a range of mycotoxins, including fumonisins. In Asia, rice (Oryza sativa) is a staple cereal and is occasionally colonized by this fungus without obvious physiological changes. F. proliferatum is closely related to Gibberella fujikuroi (anamorph F. fujikuroi) responsible for Bakanae disease in rice; however there are few reports of F. proliferatum as a rice pathogen. In this study, we examined the pathogenic potential of F. proliferatum in rice plants with respect to browning, fumonisin production, and survival rates in rice grains. Fungal inoculation was conducted by spraying a conidial suspension of F. proliferatum onto rice plants during the flowering period. Browning was found on the stalk, leaf, and ear of rice. Fumonisin B(1) was detected at levels from trace to 21 ng/g grains, using tandem mass spectrometry. Fungal recovery after 6 months indicated that F. proliferatum had high affinity to rice plants being still viable in grains. From this study, it can be concluded that F. proliferatum is a possible pathogen of rice and possesses a potential to produce fumonisin B(1) in rice grains in the field. Copyright © 2012 Elsevier B.V. All rights reserved.

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

    Science.gov (United States)

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

    2012-08-01

    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.

  18. Effects of nitrogen form on growth, CO₂ assimilation, chlorophyll fluorescence, and photosynthetic electron allocation in cucumber and rice plants.

    Science.gov (United States)

    Zhou, Yan-hong; Zhang, Yi-li; Wang, Xue-min; Cui, Jin-xia; Xia, Xiao-jian; Shi, Kai; Yu, Jing-quan

    2011-02-01

    Cucumber and rice plants with varying ammonium (NH(4)(+)) sensitivities were used to examine the effects of different nitrogen (N) sources on gas exchange, chlorophyll (Chl) fluorescence quenching, and photosynthetic electron allocation. Compared to nitrate (NO(3)(-))-grown plants, cucumber plants grown under NH(4)(+)-nutrition showed decreased plant growth, net photosynthetic rate, stomatal conductance, intercellular carbon dioxide (CO(2)) level, transpiration rate, maximum photochemical efficiency of photosystem II, and O(2)-independent alternative electron flux, and increased O(2)-dependent alternative electron flux. However, the N source had little effect on gas exchange, Chl a fluorescence parameters, and photosynthetic electron allocation in rice plants, except that NH(4)(+)-grown plants had a higher O(2)-independent alternative electron flux than NO(3)(-)-grown plants. NO(3)(-) reduction activity was rarely detected in leaves of NH(4)(+)-grown cucumber plants, but was high in NH(4)(+)-grown rice plants. These results demonstrate that significant amounts of photosynthetic electron transport were coupled to NO(3)(-) assimilation, an effect more significant in NO(3)(-)-grown plants than in NH(4)(+)-grown plants. Meanwhile, NH(4)(+)-tolerant plants exhibited a higher demand for the reduced form of nicotinamide adenine dinucleotide phosphate (NADPH) for NO(3)(-) reduction, regardless of the N form supplied, while NH(4)(+)-sensitive plants had a high water-water cycle activity when NH(4)(+) was supplied as the sole N source.

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

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Bhupinder, E-mail: bhupindersinghiari@yahoo.co [Nuclear Research Laboratory, Indian Agricultural Research Institute, New Delhi 110 012 (India); Datta, Partha Sarathi [Nuclear Research Laboratory, Indian Agricultural Research Institute, New Delhi 110 012 (India)

    2010-08-15

    We recently reported the use of low dose gamma irradiation to improve plant vigor, grain development and yield attributes of wheat (). 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.

  20. Effects of climate change on plant population growth rate and community composition change.

    Science.gov (United States)

    Chang, Xiao-Yu; Chen, Bao-Ming; Liu, Gang; Zhou, Ting; Jia, Xiao-Rong; Peng, Shao-Lin

    2015-01-01

    The impacts of climate change on forest community composition are still not well known. Although directional trends in climate change and community composition change were reported in recent years, further quantitative analyses are urgently needed. Previous studies focused on measuring population growth rates in a single time period, neglecting the development of the populations. Here we aimed to compose a method for calculating the community composition change, and to testify the impacts of climate change on community composition change within a relatively short period (several decades) based on long-term monitoring data from two plots-Dinghushan Biosphere Reserve, China (DBR) and Barro Colorado Island, Panama (BCI)-that are located in tropical and subtropical regions. We proposed a relatively more concise index, Slnλ, which refers to an overall population growth rate based on the dominant species in a community. The results indicated that the population growth rate of a majority of populations has decreased over the past few decades. This decrease was mainly caused by population development. The increasing temperature had a positive effect on population growth rates and community change rates. Our results promote understanding and explaining variations in population growth rates and community composition rates, and are helpful to predict population dynamics and population responses to climate change.

  1. Effects of climate change on plant population growth rate and community composition change.

    Directory of Open Access Journals (Sweden)

    Xiao-Yu Chang

    Full Text Available The impacts of climate change on forest community composition are still not well known. Although directional trends in climate change and community composition change were reported in recent years, further quantitative analyses are urgently needed. Previous studies focused on measuring population growth rates in a single time period, neglecting the development of the populations. Here we aimed to compose a method for calculating the community composition change, and to testify the impacts of climate change on community composition change within a relatively short period (several decades based on long-term monitoring data from two plots-Dinghushan Biosphere Reserve, China (DBR and Barro Colorado Island, Panama (BCI-that are located in tropical and subtropical regions. We proposed a relatively more concise index, Slnλ, which refers to an overall population growth rate based on the dominant species in a community. The results indicated that the population growth rate of a majority of populations has decreased over the past few decades. This decrease was mainly caused by population development. The increasing temperature had a positive effect on population growth rates and community change rates. Our results promote understanding and explaining variations in population growth rates and community composition rates, and are helpful to predict population dynamics and population responses to climate change.

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

    Science.gov (United States)

    Liao, Z; Rasmussen, V; Odegaard, H

    2003-01-01

    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.

  3. Plant resting site preferences and parity rates among the vectors of Rift Valley Fever in northeastern Kenya.

    Science.gov (United States)

    Arum, Samwel O; Weldon, Christopher W; Orindi, Benedict; Tigoi, Caroline; Musili, Francis; Landmann, Tobias; Tchouassi, David P; Affognon, Hippolyte D; Sang, Rosemary

    2016-05-31

    Mosquito lifespan can influence the circulation of disease causing pathogens because it affects the time available for infection and transmission. The life-cycle of mosquitoes is determined by intrinsic and environmental factors, which can include the availability of hosts and suitable resting environments that shelter mosquitoes from extreme temperature and desiccating conditions. This study determined the parity rates (an indirect measure of survival) and plant resting preference of vectors of Rift Valley fever (RVF) in northeastern Kenya. Resting mosquitoes were trapped during the rainy and the dry season using a Prokopack aspirator from vegetation, whereas general adult populations were trapped using CDC light traps. At each site, sampling was conducted within a 1 km(2) area, subdivided into 500 × 500 m quadrants and four 250 × 250 m sub-quadrants from which two were randomly selected as sampling units. In each sampling unit, plants were randomly selected for aspiration of mosquitoes. Only Aedes mcintoshi and Ae. ochraceus were dissected to determine parity rates while all mosquito species were used to assess plant resting preference. Overall, 1124 (79 %, 95 % CI = 76.8-81.1 %) mosquitoes were parous. There was no significant difference in the number of parous Ae. mcintoshi and Ae. ochraceus. Parity was higher in the rainy season than in the dry season. Daily survival rate was estimated to be 0.93 and 0.92 among Ae. ochraceus and Ae. mcintoshi, respectively. Duosperma kilimandscharicum was the most preferred plant species with the highest average capture of primary (3.64) and secondary (5.83) vectors per plant, while Gisekia africana was least preferred. Survival rate of each of the two primary vectors of RVF reported in this study may provide an indication that these mosquitoes can potentially play important roles in the circulation of diseases in northern Kenya. Resting preference of the mosquitoes in vegetation may influence their

  4. Impact on ambient dose rate in metropolitan Tokyo from the Fukushima Daiichi Nuclear Power Plant accident.

    Science.gov (United States)

    Inoue, Kazumasa; Tsuruoka, Hiroshi; Van Le, Tan; Arai, Moeko; Saito, Kyoko; Fukushi, Masahiro

    2016-07-01

    A car-borne survey was made in metropolitan Tokyo, Japan, in December 2014 to estimate external dose. This survey was conducted for all municipalities of Tokyo and the results were compared with measurements done in 2003. The ambient dose rate measured in the whole area of Tokyo in December 2014 was 60 nGy h(-1) (23-142 nGy h(-1)), which was 24% higher than the rate in 2003. Higher dose rates (>70 nGy h(-1)) were observed on the eastern and western ends of Tokyo; furthermore, the contribution ratio from artificial radionuclides ((134)Cs and (137)Cs) to ambient dose rate in eastern Tokyo was twice as high as that of western Tokyo. Based on the measured ambient dose rate, the effective dose rate after the accident was estimated to be 0.45 μSv h(-1) in Tokyo. This value was 22% higher than the value before the accident as of December 2014.

  5. Needle longevity, photosynthetic rate and nitrogen concentration of eight spruce taxa planted in northern Japan.

    Science.gov (United States)

    Kayama, Masazumi; Kitaoka, Satoshi; Wang, Wenjie; Choi, Dongsu; Koike, Takayoshi

    2007-11-01

    Growth characteristics of Picea glehnii Masters, P. jezoensis (Sieb. et Zucc) Carr., P. jezoensis var. hondoensis (Mayr) Rehder and P. shirasawae Hayashi from Japan, P. abies (L.) Karst. from Europe and P. glauca Voss, P. mariana Britt., Sterns and Pogg. and P. rubens Sarg. from North America were compared. The trees were grown in similar conditions at the Tomakomai Experimental Forest of Hokkaido University in northern Japan. Tree growth, needle biomass, longevity, photosynthetic rate, nitrogen concentration and specific leaf area (SLA) were measured, and photosynthetic nitrogen-use efficiency was calculated. Picea jezoensis, P. jezoensis var. hondoensis, P. abies and P. glauca had high growth rates, high photosynthetic rates in young needles, high needle nitrogen concentrations and short needle life spans. In contrast, P. glehnii, P. shirasawae, P. mariana and P. rubens had low growth and photosynthetic rates, low needle nitrogen concentrations, long needle life spans and maintained a high photosynthetic nitrogen-use efficiency in older needles. Examination of relationships between several growth parameters of the eight taxa revealed positive correlations between SLA and mass-based photosynthetic rate and between SLA and mass-based nitrogen concentration, whereas mass-based photosynthetic rate and mass-based nitrogen concentration were negatively correlated with needle longevity. The species differed greatly in growth characteristics despite being grown in similar conditions.

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

    DEFF Research Database (Denmark)

    Schurgers, Guy; Lagergren, F.; Molder, M.

    2015-01-01

    the importance of vertical variations in light, temperature, CO2 concentration and humidity within the canopy for fluxes of photosynthesis and transpiration of a boreal coniferous forest in central Sweden. A leaf-level photosynthesis-stomatal conductance model was used for aggregating these processes to canopy...... abovecanopy and within-canopy humidity, and despite large gradients in CO2 concentration during early morning hours after nights with stable conditions, neither humidity nor CO2 played an important role for vertical heterogeneity of photosynthesis and transpiration....

  7. Evaluating physiological responses of plants to salinity stress

    KAUST Repository

    Negrão, S.

    2016-10-06

    Background Because soil salinity is a major abiotic constraint affecting crop yield, much research has been conducted to develop plants with improved salinity tolerance. Salinity stress impacts many aspects of a plant’s physiology, making it difficult to study in toto. Instead, it is more tractable to dissect the plant’s response into traits that are hypothesized to be involved in the overall tolerance of the plant to salinity. Scope and conclusions We discuss how to quantify the impact of salinity on different traits, such as relative growth rate, water relations, transpiration, transpiration use efficiency, ionic relations, photosynthesis, senescence, yield and yield components. We also suggest some guidelines to assist with the selection of appropriate experimental systems, imposition of salinity stress, and obtaining and analysing relevant physiological data using appropriate indices. We illustrate how these indices can be used to identify relationships amongst the proposed traits to identify which traits are the most important contributors to salinity tolerance. Salinity tolerance is complex and involves many genes, but progress has been made in studying the mechanisms underlying a plant’s response to salinity. Nevertheless, several previous studies on salinity tolerance could have benefited from improved experimental design. We hope that this paper will provide pertinent information to researchers on performing proficient assays and interpreting results from salinity tolerance experiments.

  8. The Rise of Flowering Plants and Land Surface Physics: The Cretaceous and Eocene Were Different

    Science.gov (United States)

    Upchurch, G. R.; Feild, T.

    2010-12-01

    The Cretaceous and Eocene have served as the poster children of past greenhouse climates. One difference between the two time periods is that angiosperms (flowering plants) underwent a major diversification and rise to dominance during the mid-Cretaceous to Paleocene. Flowering plants differ from all other living and fossil plants in having significantly higher rates of transpiration and photosynthesis, which in modern leaves correlate with the density of venation (Dv), a feature that can be measured directly from fossils. This increase in Dv, coupled with an increase in the abundance of angiosperms, is thought to have had major impact on the climate system. This is, in part, because transpiration plays an important role in determining the ratio of sensible to latent heat flux from the land surface and in determining precipitation rate in regions such as the equatorial rainforest. Analysis of Dv in fossil leaves indicates two phases of increase in transpiration rate for angiosperms during the Cretaceous-Paleocene. The oldest known angiosperms (Aptian-early Albian) have a low Dv characteristic of extant and fossil ferns and gymnosperms. At this time angiosperms are low-stature plants of minor importance in terms of relative abundance and diversity (<5%). The first phase of Dv increase occurs during the Late Albian to Cenomanian, where average Dv is 40% greater than that of conifers and ferns, and maximum Dv reaches levels characteristic of many trees from the temperate zone. This first phase coincides with the first local dominance of angiosperms, the first occurrence of moderate to large angiosperm trees (up to 1 m in diameter) , and the first common occurrence of angiosperms in the Arctic. The second phase of Dv increase occurs during the Maastrichtian to Paleocene, where average Dv reaches levels characteristic of modern tropical forests and maximum Dv reaches the level found in highly productive modern vegetation. This second phase coincides with the rise to

  9. Optical crop sensor for variable-rate nitrogen fertilization in corn: i - plant nutrition and dry matter production

    Directory of Open Access Journals (Sweden)

    Jardes Bragagnolo

    2013-10-01

    Full Text Available Variable-rate nitrogen fertilization (VRF based on optical spectrometry sensors of crops is a technological innovation capable of improving the nutrient use efficiency (NUE and mitigate environmental impacts. However, studies addressing fertilization based on crop sensors are still scarce in Brazilian agriculture. This study aims to evaluate the efficiency of an optical crop sensor to assess the nutritional status of corn and compare VRF with the standard strategy of traditional single-rate N fertilization (TSF used by farmers. With this purpose, three experiments were conducted at different locations in Southern Brazil, in the growing seasons 2008/09 and 2010/11. The following crop properties were evaluated: above-ground dry matter production, nitrogen (N content, N uptake, relative chlorophyll content (SPAD reading, and a vegetation index measured by the optical sensor N-Sensor® ALS. The plants were evaluated in the stages V4, V6, V8, V10, V12 and at corn flowering. The experiments had a completely randomized design at three different sites that were analyzed separately. The vegetation index was directly related to above-ground dry matter production (R² = 0.91; p<0.0001, total N uptake (R² = 0.87; p<0.0001 and SPAD reading (R² = 0.63; p<0.0001 and inversely related to plant N content (R² = 0.53; p<0.0001. The efficiency of VRF for plant nutrition was influenced by the specific climatic conditions of each site. Therefore, the efficiency of the VRF strategy was similar to that of the standard farmer fertilizer strategy at sites 1 and 2. However, at site 3 where the climatic conditions were favorable for corn growth, the use of optical sensors to determine VRF resulted in a 12 % increase in N plant uptake in relation to the standard fertilization, indicating the potential of this technology to improve NUE.

  10. Effects of soil water deficits on three genotypes of potted Campanula medium plants during bud formation stage

    DEFF Research Database (Denmark)

    Mao, Hongyu; Sun, Yanqi; Müller, Renate;

    2014-01-01

    , the floral bud abortion rate in the D plants was significantly higher for G100 as compared with G102 and G104. It is concluded that in potted ornamentals, a low transpiration rate, hereby a slow rate of soil water depletion, is crucial for maintaining postharvest quality under drought stress.......Potted ornamental plants are often exposed to drought stress during shipping and retailing, which decreases the value and postharvest quality. Thus, selection of genotypes which can better withstand soil water deficits is essential for sustainable production. Here, the response of three genotypes...... of potted Campanula medium (denoted as G100, G102 and G104) to progressive soil drying was investigated and their post-production performance was evaluated for four weeks. The potted plants were grown in a climate controlled greenhouse and were either well-watered (W) or drought-stressed (D) at floral bud...

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

    Science.gov (United States)

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

    2014-05-01

    Water management and understanding of irrigation efficiency could be significantly improved if the components of evapotranspiration (ET) in row-crop systems (plants and soil interrows) could be quantified separately. This evaporation/transpiration (E/T) partition, and its daily and seasonal evolution, depends on a variety of biophysical and environmental factors. In this work we present an operational method to provide continuous E/T results avoiding soil or canopy disturbance. This technique is based on the combination of the surface-atmosphere energy exchange modeling together with an accurate remote thermal characterization of the crop elements. An experiment was carried out in a row-crop vineyard in Mallorca, Spain, from June 2012 to May 2013. A set of 6 thermal-infrared radiometers (IRTs) were mounted in a mast placed in the middle of a vineyard N-S row. Two IRTs pointed to the soil between rows and other two pointed to the plants from a frontal view, measuring both east and west sides of the row. A fifth IRT pointed upward to collect the downwelling sky radiance and the remaining IRT was mounted at 4.5-m height over the canopy measuring the composed soil-canopy temperature. Measurements of the four components of the net radiation over the canopy and soil heat fluxes, as well as air temperature, humidity, wind speed, and soil moisture, were collected and stored in 15-min averages. A two-source energy balance approach was applied to the vineyard from its appropriate thermal characterization. Total and separate soil/canopy components of net radiation, soil, sensible and latent heat fluxes were obtained every 15 minutes and averaged at hourly and daily scales. Comparison between observed and modeled values of available surface energy showed relative errors below 15%. An analysis of the partition E/T was conducted along the vineyard growing season and the different phenological stages. In this experiment, interrow soil evaporation reached as much as 1/3 of the

  12. Removal rate and releases of polybrominated diphenyl ethers in two wastewater treatment plants, Korea

    Science.gov (United States)

    Lee, Hyo Jin; Kim, Gi Beum

    2017-06-01

    Wastewater treatment plants (WWTPs) play an important role in minimizing the release of many pollutants into the environment. Nineteen congeners in two WWTPs in Korea were determined to investigate the occurrence and fate of polybrominated diphenyl ethers (PBDEs) during wastewater treatment processes. The concentration of total PBDEs was 69.6 and 183 ng/L in influent, which declined to 1.59 and 2.34 ng/L in the final effluent, respectively (Tongyeong and Jinhae WWTPs). PBDEs were found to exist mostly in the particulate phase of wastewater, which rendered sedimentation efficient for the removal of PBDEs. BDE-209 was the predominant congener in the influent and sludge. Most of the PBDEs entering the WWTPs presumably ended up in the sludge, with WWTP in Korea.

  13. Impact of within-field variability in soil hydraulic properties on transpiration fluxes and crop yields: A numerical study

    NARCIS (Netherlands)

    Hupet, F.; Dam, van J.C.; Vanclooster, M.

    2004-01-01

    By means of numerical modeling we investigate the impact of within-field variability in the soil hydraulic properties on actual transpiration and dry matter yield for three different climate scenarios. We first show that the sensitivity of the simulated actual transpiration and dry matter yield to s

  14. Development of An Optimization Method for Determining Automation Rate in Nuclear Power Plants

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Seung Min; Seong, Poong Hyun [KAIST, Daejeon (Korea, Republic of); Kim, Jong Hyun [KEPCO, Ulsan (Korea, Republic of)

    2014-08-15

    Since automation was introduced in various industrial fields, it has been known that automation provides positive effects like greater efficiency and fewer human errors, and negative effect defined as out-of-the-loop (OOTL). Thus, before introducing automation in nuclear field, the estimation of the positive and negative effects of automation on human operators should be conducted. In this paper, by focusing on CPS, the optimization method to find an appropriate proportion of automation is suggested by integrating the suggested cognitive automation rate and the concepts of the level of ostracism. The cognitive automation rate estimation method was suggested to express the reduced amount of human cognitive loads, and the level of ostracism was suggested to express the difficulty in obtaining information from the automation system and increased uncertainty of human operators' diagnosis. The maximized proportion of automation that maintains the high level of attention for monitoring the situation is derived by an experiment, and the automation rate is estimated by the suggested automation rate estimation method. It is expected to derive an appropriate inclusion proportion of the automation system avoiding the OOTL problem and having maximum efficacy at the same time.

  15. Groundwater Availability Alters Soil-plant Nutrient Cycling in a Stand of Invasive, N-fixing Phreatophytes

    Science.gov (United States)

    Dudley, B. D.; Miyazawa, Y.; Hughes, F.; Ostertag, R.; Kettwich, S. K.; MacKenzie, R.; Dulaiova, H.; Waters, C. A.; Bishop, J.; Giambelluca, T. W.

    2013-12-01

    N-fixing phreatophytic trees are common in arid and semi-arid regions worldwide, and can play significant roles in modifying hydrology and soil-plant nutrient cycling where they are present. In light of reductions in groundwater levels in many arid regions we estimated annual transpiration rates at a stand level, and alterations to C, N and P accretion in soils as a function of groundwater depth in a ca.120 year old stand of Prosopis pallida along an elevation gradient in coastal leeward Hawaii. We measured sapflow and stand level sapwood area to quantify transpiration, and calculated groundwater transpiration rates using P. pallida stem water δ18O values. By measuring soil resistivity, we were able to compare the volume of groundwater transpired by these trees to groundwater depth across the stand. We examined nutrient deposition and accretion in soils in lowland areas of the stand with accessible shallow groundwater, compared to upland areas with no groundwater access, as indicated by stem water δ18O values. Resistivity results suggested that groundwater was at a height close to sea level throughout the stand. Transpiration was around 1900 m3 ha-1 year-1 in the areas of the stand closest to the sea (where groundwater was at around 1-4 m below ground level) and decreased to around a tenth of that volume where groundwater was not accessible. Litterfall rates over the course of the year studied were 17 times greater at lowland sites, but this litterfall contributed ca. 24 times the N, and 35 times the P of upland sites. Thus, groundwater access contributed to the total mass of nitrogen and phosphorus deposited in the form of litter through higher litter quantity and quality. Total N content of soils was 4.7 times greater and inorganic N pools were eight times higher at lowland plots. These results suggest that groundwater depth can have strong effects on soil-plant nutrient cycling, so that reductions in the availability of shallow groundwater are likely to impact

  16. Constraining Ecosystem Gross Primary Production and Transpiration with Measurements of Photosynthetic 13CO2 Discrimination

    Science.gov (United States)

    Blonquist, J. M.; Wingate, L.; Ogeé, J.; Bowling, D. R.

    2011-12-01

    The stable carbon isotope composition of atmospheric CO2 (δ13Ca) can provide useful information on water use efficiency (WUE) dynamics of terrestrial ecosystems and potentially constrain models of CO2 and water fluxes at the land surface. This is due to the leaf-level relationship between photosynthetic 13CO2 discrimination (Δ), which influences δ13Ca, and the ratio of leaf intercellular to atmospheric CO2 mole fractions (Ci / Ca), which is related to WUE and is determined by the balance between C assimilation (CO2 demand) and stomatal conductance (CO2 supply). We used branch-scale Δ derived from tunable diode laser absorption spectroscopy measurements collected in a Maritime pine forest to estimate Ci / Ca variations over an entire growing season. We combined Ci / Ca estimates with rates of gross primary production (GPP) derived from eddy covariance (EC) to estimate canopy-scale stomatal conductance (Gs) and transpiration (T). Estimates of T were highly correlated to T estimates derived from sapflow data (y = 1.22x + 0.08; r2 = 0.61; slope P MuSICA) (y = 0.88x - 0.05; r2 = 0.64; slope P MuSICA (y = 1.10 + 0.42; r2 = 0.50; slope P < 0.001). Results demonstrate that the leaf-level relationship between Δ and Ci / Ca can be extended to the canopy-scale and that Δ measurements have utility for partitioning ecosystem-scale CO2 and water fluxes.

  17. Effect of radiocesium transfer on ambient dose rate in forest environments affected by the Fukushima Nuclear Power Plant accident

    Science.gov (United States)

    Kato, H.

    2015-12-01

    We investigated the transfer of canopy-intercepted radiocesium to the forest floor during 3 years following the Fukushima Daiichi Nuclear Power Plant accident. The cesium-137 (Cs-137) contents in throughfall, stemflow, and litterfall were monitored in two coniferous stands (plantation of Japanese cedar) and a deciduous broad-leaved forest stand (Japanese oak with red pine). We also measured the ambient dose rate (ADR) at different heights in the forest using a survey meter and a portable Ge gamma-ray detector. Total Cs-137 deposition flux from the canopy to forest floor for the mature cedar, young cedar, and the mixed broad-leaved stands were 166 kBq/m2, 174 kBq/m2, and 60 kBq/m2, respectively. These values correspond to 38%, 40% and 13% of total atmospheric input after the accident. The ambient dose rate in forest exhibited height dependency and its vertical distribution varied with forest type and stand age. The ambient dose rate showed an exponential decrease with time for all the forest sites, however the decreasing trend differed depending on the height of dose measurement and forest type. The ambient dose rate at the canopy (approx. 10 m-height) decreased faster than that expected from physical decay of the two radiocesium isotopes, whereas those at the forest floor varied between the three forest stands. The radiocesium deposition via throughfall seemed to increase ambient dose rate during the first 200 days after the accident, however there was no clear relationship between litterfall and ambient dose rate since 400 days after the accident. These data suggested that the ambient dose rate in forest environment varied both spatially and temporally reflecting the transfer of radiocesium from canopy to forest floor. However, further monitoring investigation and analysis are required to determine the effect of litterfall on long-term trend of ambient dose rate in forest environments.

  18. Association of biodiversity with the rates of micropollutant biotransformations among full-scale wastewater treatment plant communities.

    Science.gov (United States)

    Johnson, David R; Helbling, Damian E; Lee, Tae Kwon; Park, Joonhong; Fenner, Kathrin; Kohler, Hans-Peter E; Ackermann, Martin

    2015-01-01

    Biodiversities can differ substantially among different wastewater treatment plant (WWTP) communities. Whether differences in biodiversity translate into differences in the provision of particular ecosystem services, however, is under active debate. Theoretical considerations predict that WWTP communities with more biodiversity are more likely to contain strains that have positive effects on the rates of particular ecosystem functions, thus resulting in positive associations between those two variables. However, if WWTP communities were sufficiently biodiverse to nearly saturate the set of possible positive effects, then positive associations would not occur between biodiversity and the rates of particular ecosystem functions. To test these expectations, we measured the taxonomic biodiversity, functional biodiversity, and rates of 10 different micropollutant biotransformations for 10 full-scale WWTP communities. We have demonstrated that biodiversity is positively associated with the rates of specific, but not all, micropollutant biotransformations. Thus, one cannot assume whether or how biodiversity will associate with the rate of any particular micropollutant biotransformation. We have further demonstrated that the strongest positive association is between biodiversity and the collective rate of multiple micropollutant biotransformations. Thus, more biodiversity is likely required to maximize the collective rates of multiple micropollutant biotransformations than is required to maximize the rate of any individual micropollutant biotransformation. We finally provide evidence that the positive associations are stronger for rare micropollutant biotransformations than for common micropollutant biotransformations. Together, our results are consistent with the hypothesis that differences in biodiversity can indeed translate into differences in the provision of particular ecosystem services by full-scale WWTP communities. Copyright © 2015, American Society for

  19. From leaf to whole-plant water use efficiency (WUE in complex canopies: Limitations of leaf WUE as a selection target

    Directory of Open Access Journals (Sweden)

    Hipólito Medrano

    2015-06-01

    Full Text Available Plant water use efficiency (WUE is becoming a key issue in semiarid areas, where crop production relies on the use of large volumes of water. Improving WUE is necessary for securing environmental sustainability of food production in these areas. Given that climate change predictions include increases in temperature and drought in semiarid regions, improving crop WUE is mandatory for global food production. WUE is commonly measured at the leaf level, because portable equipment for measuring leaf gas exchange rates facilitates the simultaneous measurement of photosynthesis and transpiration. However, when those measurements are compared with daily integrals or whole-plant estimates of WUE, the two sometimes do not agree. Scaling up from single-leaf to whole-plant WUE was tested in grapevines in different experiments by comparison of daily integrals of instantaneous water use efficiency [ratio between CO2 assimilation (AN and transpiration (E; AN/E] with midday AN/E measurements, showing a low correlation, being worse with increasing water stress. We sought to evaluate the importance of spatial and temporal variation in carbon and water balances at the leaf and plant levels. The leaf position (governing average light interception in the canopy showed a marked effect on instantaneous and daily integrals of leaf WUE. Night transpiration and respiration rates were also evaluated, as well as respiration contributions to total carbon balance. Two main components were identified as filling the gap between leaf and whole plant WUE: the large effect of leaf position on daily carbon gain and water loss and the large flux of carbon losses by dark respiration. These results show that WUE evaluation among genotypes or treatments needs to be revised.

  20. From leaf to whole-plant water use efficiency (WUE) in complex canopies:Limitations of leaf WUE as a selection target

    Institute of Scientific and Technical Information of China (English)

    Hiplito Medrano; Magdalena Toms; Sebasti Martorell; Jaume Flexas; Esther Hernndez; Joan Rossell; Alicia Pou; Jos-Mariano Escalona; Josefina Bota

    2015-01-01

    Plant water use efficiency (WUE) is becoming a key issue in semiarid areas, where crop production relies on the use of large volumes of water. Improving WUE is necessary for securing environmental sustainability of food production in these areas. Given that climate change predictions include increases in temperature and drought in semiarid regions, improving crop WUE is mandatory for global food production. WUE is commonly measured at the leaf level, because portable equipment for measuring leaf gas exchange rates facilitates the simultaneous measurement of photosynthesis and transpiration. However, when those measurements are compared with daily integrals or whole-plant estimates of WUE, the two sometimes do not agree. Scaling up from single-leaf to whole-plant WUE was tested in grapevines in different experiments by comparison of daily integrals of instantaneous water use efficiency [ratio between CO2 assimilation (AN) and transpiration (E); AN/E] with midday AN/E measurements, showing a low correlation, being worse with increasing water stress. We sought to evaluate the importance of spatial and temporal variation in carbon and water balances at the leaf and plant levels. The leaf position (governing average light interception) in the canopy showed a marked effect on instantaneous and daily integrals of leaf WUE. Night transpiration and respiration rates were also evaluated, as well as respiration contributions to total carbon balance. Two main components were identified as filling the gap between leaf and whole plant WUE:the large effect of leaf position on daily carbon gain and water loss and the large flux of carbon losses by dark respiration. These results show that WUE evaluation among genotypes or treatments needs to be revised.

  1. From leaf to whole-plant water use efficiency(WUE)in complex canopies:Limitations of leaf WUE as a selection target

    Institute of Scientific and Technical Information of China (English)

    Hipólito; Medrano; Magdalena; Tomás; Sebastià; Martorell; aume; Flexas; Esther; Hernández; Joan; Rosselló; Alicia; Pou; José-Mariano; Escalona; Josefina; Bota

    2015-01-01

    Plant water use efficiency(WUE) is becoming a key issue in semiarid areas, where crop production relies on the use of large volumes of water. Improving WUE is necessary for securing environmental sustainability of food production in these areas. Given that climate change predictions include increases in temperature and drought in semiarid regions,improving crop WUE is mandatory for global food production. WUE is commonly measured at the leaf level, because portable equipment for measuring leaf gas exchange rates facilitates the simultaneous measurement of photosynthesis and transpiration. However,when those measurements are compared with daily integrals or whole-plant estimates of WUE, the two sometimes do not agree. Scaling up from single-leaf to whole-plant WUE was tested in grapevines in different experiments by comparison of daily integrals of instantaneous water use efficiency [ratio between CO2assimilation(AN) and transpiration(E); AN/E] with midday AN/E measurements, showing a low correlation, being worse with increasing water stress. We sought to evaluate the importance of spatial and temporal variation in carbon and water balances at the leaf and plant levels. The leaf position(governing average light interception) in the canopy showed a marked effect on instantaneous and daily integrals of leaf WUE. Night transpiration and respiration rates were also evaluated, as well as respiration contributions to total carbon balance. Two main components were identified as filling the gap between leaf and whole plant WUE: the large effect of leaf position on daily carbon gain and water loss and the large flux of carbon losses by dark respiration. These results show that WUE evaluation among genotypes or treatments needs to be revised.

  2. Evaluation of diel patterns of relative changes in cell turgor of tomato plants using leaf patch clamp pressure probes.

    Science.gov (United States)

    Lee, Kang M; Driever, Steven M; Heuvelink, Ep; Rüger, Simon; Zimmermann, Ulrich; de Gelder, Arie; Marcelis, Leo F M

    2012-12-01

    Relative changes in cell turgor of leaves of well-watered tomato plants were evaluated using the leaf patch clamp pressure probe (LPCP) under dynamic greenhouse climate conditions. LPCP changes, a measure for relative changes in cell turgor, were monitored at three different heights of transpiring and non-transpiring leaves of tomato plants on sunny and cloudy days simultaneously with whole plant water uptake. Clear diel patterns were observed for relative changes of cell turgor of both transpiring and non-transpiring leaves, which were stronger on sunny days than on cloudy days. A clear effect of canopy height was also observed. Non-transpiring leaves showed relative changes in cell turgor that closely followed plant water uptake throughout the day. However, in the afternoon the relative changes of cell turgor of the transpiring leaves displayed a delayed response in comparison to plant water uptake. Subsequent recovery of cell turgor loss of transpiring leaves during the following night appeared insufficient, as the pre-dawn turgescent state similar to the previous night was not attained. Copyright © Physiologia Plantarum 2012.

  3. Is whole-plant photosynthetic rate proportional to leaf area? A test of scalings and a logistic equation by leaf demography census.

    Science.gov (United States)

    Koyama, Kohei; Kikuzawa, Kihachiro

    2009-05-01

    Allometric scalings and a logistic equation assume that whole-plant photosynthetic rate under resource-unlimited conditions is proportional to leaf area. We tested this proportionality for the herb Helianthus tuberosus. During growth, we repeatedly measured the percentage of leaves with high, medium, and low photosynthetic capacity to estimate the whole-plant sum of photosynthetic capacity. We found that the whole-plant sum of the light-saturated photosynthetic rate of leaves is proportional to the whole-plant leaf area, disregarding the dynamics of the leaf population. We also found that the daily photosynthesis of each leaf appeared as a linear function of the light-saturated photosynthetic rate of that leaf, as predicted by the optimization theory. Using those results, we expressed whole-plant photosynthetic rate as a product of the light-saturated whole-plant photosynthetic rate and an efficiency index that reflects resource limitation as in the logistic equation. This efficiency decreased with increasing leaf area, reflecting light limitation. Therefore, realized whole-plant photosynthetic rate is not proportional to leaf area. These "diminishing returns" are well explained by a simple saturating curve, such as the logistic equation.

  4. Characteristics of photosynthesis in rice plants transformed with an antisense Rubisco activase gene

    Institute of Scientific and Technical Information of China (English)

    金松恒; 蒋德安; 李雪芹; 孙骏威

    2004-01-01

    Transgenic rice plants with an antisense gene inserted via Agrobacterium tumefaciens were used to explore the impact of the reduction of Rubisco activase (RCA) on Rubisco and photosynthesis. In this study, transformants containing 15% to 35% wild type Rubisco activase were selected, which could survive in ambient CO2 concentration but grew slowly compared with wild type controls. Gas exchange measurements indicated that the rate of photosynthesis decreased sig-nificantly, while stomatal conductance and transpiration rate did not change; and that the intercellular CO2 concentration even increased. Rubisco determination showed that these plants had approximately twice as much Rubisco as the wild types,although they showed 70% lower rate of photosynthesis, whichRubsico activase and/or the reduction in carbamylation.was likely an acclimation response to the reduction in Rubsico activase and/or the reduction in carbamylation.

  5. Characteristics of photosynthesis in rice plants transformed with an antisense Rubisco activase gene

    Institute of Scientific and Technical Information of China (English)

    金松恒; 蒋德安; 李雪芹; 孙骏威

    2004-01-01

    Transgenic rice plants with an antisense gene inserted via Agrobacterium tumefaciens were used to explore the impact of the reduction of Rubisco activase (RCA) on Rubisco and photosynthesis. In this study, transformants containing 15% to 35% wild type Rubisco activase were selected, which could survive in ambient CO2 concentration but grew slowly compared with wild type controls. Gas exchange measurements indicated that the rate of photosynthesis decreased significantly, while stomatal conductance and transpiration rate did not change; and that the intercellular CO2 concentration even increased. Rubisco determination showed that these plants had approximately twice as much Rubisco as the wild types,although they showed 70% lower rate of photosynthesis, which was likely an acclimation response to the reduction inRubsico activase and/or the reduction in carbamylation.

  6. Characteristics of photosynthesis in rice plants transformed with an antisense Rubisco activase gene.

    Science.gov (United States)

    Jin, Song-Heng; Jiang, De-An; Li, Xue-Qin; Sun, Jun-Wei

    2004-08-01

    Transgenic rice plants with an antisense gene inserted via Agrobacterium tumefaciens were used to explore the impact of the reduction of Rubisco activase (RCA) on Rubisco and photosynthesis. In this study, transformants containing 15% to 35% wild type Rubisco activase were selected, which could survive in ambient CO2 concentration but grew slowly compared with wild type controls. Gas exchange measurements indicated that the rate of photosynthesis decreased significantly, while stomatal conductance and transpiration rate did not change; and that the intercellular CO2 concentration even increased. Rubisco determination showed that these plants had approximately twice as much Rubisco as the wild types, although they showed 70% lower rate of photosynthesis, which was likely an acclimation response to the reduction in Rubsico activase and/or the reduction in carbamylation.

  7. Forest transpiration from sap flux density measurements in a Southeastern Coastal Plain riparian buffer system

    Science.gov (United States)

    Forested riparian buffers are prevalent throughout the Southeastern Coastal Plain Region of the United States (US). Because they make up a significant portion of the regional landscape, transpiration within these riparian buffers is believed to have an important impact on the hydrologic budget of r...

  8. Predicting of regional transpiration at elevated atmospheric CO2: influence of the PBL vegetation interaction.

    NARCIS (Netherlands)

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

    1997-01-01

    A coupled planetary boundary layer (PBL)-vegetation model is used to study the influence of the PBL-vegetation interaction and the ambient CO2 concentration on surface resistance rs and regional transpiration E. Vegetation is described using the big-leaf model in which rs is modeled by means of a

  9. Predicting of regional transpiration at elevated atmospheric CO2: influence of the PBL vegetation interaction.

    NARCIS (Netherlands)

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

    1997-01-01

    A coupled planetary boundary layer (PBL)-vegetation model is used to study the influence of the PBL-vegetation interaction and the ambient CO2 concentration on surface resistance rs and regional transpiration E. Vegetation is described using the big-leaf model in which rs is modeled by means of a co

  10. Minimizing instrumentation requirement for estimating crop water stress index and transpiration of maize

    Science.gov (United States)

    Research was conducted in northern Colorado in 2011 to estimate the Crop Water Stress Index (CWSI) and actual water transpiration (Ta) of maize under a range of irrigation regimes. The main goal was to obtain these parameters with minimum instrumentation and measurements. The results confirmed that ...

  11. Partitioning evaporation and transpiration in a maize field with heat-pulse sensors used for evaporation

    Science.gov (United States)

    Evaporation (E) and transpiration (T) occur simultaneously in many systems with varying levels of importance, yet terms are typically lumped as evapotranspiration (ET) due to difficulty with distinguishing component fluxes. Few studies have measured all three terms (ET, E, and T), and in the few cas...

  12. Effect of Putrescine, 4-PU-30, and Abscisic Acid on Maize Plants Grown under Normal, Drought, and Rewatering Conditions.

    Science.gov (United States)

    Todorov; Alexieva; Karanov

    1998-12-01

    The experiments were carried out with maize (Zea mays L.) seedlings, hybrid Kneja 530, grown hydroponically in a growth chamber. Twelve-day-old plants were foliar treated with putrescine, N1-(2-chloro-4-pyridyl)-N2-phenylurea (4-PU-30), and abscisic acid (ABA) at concentrations of 10(-5) m. Twenty-four hours later the plants were subjected to a water deficit program, induced by 15% polyethylene glycol (PEG; molecular weight, 6,000). Three days after drought stress half of the plants were transferred to nutrient solution for the next 3 days. The effects of the water shortage, rewatering, and plant growth regulator (PGR) treatment on the fresh and dry weights, leaf pigment content, proline level, relative water content (RWC), transpiration rate, activities of catalase and guaiacol peroxidase, hydrogen peroxide content, and level of the products of lipid peroxidation were studied. It was established that the application of PGRs alleviated to some extent the plant damage provoked by PEG stress. At the end of the water shortage program the plants treated with these PGRs possessed higher fresh weight than drought-subjected control seedlings. It was found also that putrescine increased the dry weight of plants. Under drought, the RWC and transpiration rate of seedlings declined, but PGR treatment reduced these effects. The accumulation of free proline, malondialdehyde, and hydrogen peroxide was prevented in PGR-treated plants compared with the water stress control. The results provided further information about the influence of putrescine, 4-PU-30, and ABA on maize plants grown under normal, drought, and rewatering conditions. Key Words. Maize-Putrescine-4-PU-30-ABA-Drought

  13. Effects of wastewater treatment plant effluent inputs on planktonic metabolic rates and microbial community composition in the Baltic Sea

    Science.gov (United States)

    Vaquer-Sunyer, Raquel; Reader, Heather E.; Muthusamy, Saraladevi; Lindh, Markus V.; Pinhassi, Jarone; Conley, Daniel J.; Kritzberg, Emma S.

    2016-08-01

    The Baltic Sea is the world's largest area suffering from eutrophication-driven hypoxia. Low oxygen levels are threatening its biodiversity and ecosystem functioning. The main causes for eutrophication-driven hypoxia are high nutrient loadings and global warming. Wastewater treatment plants (WWTP) contribute to eutrophication as they are important sources of nitrogen to coastal areas. Here, we evaluated the effects of wastewater treatment plant effluent inputs on Baltic Sea planktonic communities in four experiments. We tested for effects of effluent inputs on chlorophyll a content, bacterial community composition, and metabolic rates: gross primary production (GPP), net community production (NCP), community respiration (CR) and bacterial production (BP). Nitrogen-rich dissolved organic matter (DOM) inputs from effluents increased bacterial production and decreased primary production and community respiration. Nutrient amendments and seasonally variable environmental conditions lead to lower alpha-diversity and shifts in bacterial community composition (e.g. increased abundance of a few cyanobacterial populations in the summer experiment), concomitant with changes in metabolic rates. An increase in BP and decrease in CR could be caused by high lability of the DOM that can support secondary bacterial production, without an increase in respiration. Increases in bacterial production and simultaneous decreases of primary production lead to more carbon being consumed in the microbial loop, and may shift the ecosystem towards heterotrophy.

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

    Science.gov (United States)

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

    2012-07-01

    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.

  15. Service Power Rate and Electricity-Saving in Conventional Thermal Power Plants

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    @@ Since reforming and opening to the outside world, the power construction in China has been expanding by leaps and bounds. As of the end of 2005, the nationwide generation installed capacity made a breakthrough of 500 GW, of which thermal power units represented three-fourths.Relevant predictions indicate that the installed capacity will reach 680-730 GW in 2010 and it will exceed 1000 GW in 2020 as expected. The present situation of service power rate of thermal power units and how to make it approach and come up to world level are questions to be discussed in this paper.

  16. Water uptake efficiency of a maize plant - A simulation case study

    Science.gov (United States)

    Meunier, Félicien; Leitner, Daniel; Bodner, Gernot; Javaux, Mathieu; Schnepf, Andrea

    2014-05-01

    Water uptake by plant roots is a complex mechanism controlled by biological and physical properties of the soil-plant-atmosphere system and affects a major component of the water cycle, transpiration. This uptake of water by plants is one of the major factors of plant development. Since water uptake occurs at the roots, root architecture and hydraulic properties both play a crucial role in plant productivity. A fundamental understanding of the main processes of water uptake will enable better breeding of drought resistant plants and the improvement of irrigation strategies. In this work we analyzed the differences of root water uptake between idealized genotypes of a plant using mathematical modelling The numerical simulations were performed by the R-SWMS software (Javaux et al., 2008). The model describes 3-D water movement in soil by solving Richard's equation with a sink term representing root uptake. Water flow within the root xylem network and between soil and root is modelled based on water pressure gradients and calculated according to Doussan's model. The sink term is calculated by integration of local uptakes within rooted representative elementary volumes of soil. The plant water demand is described by a boundary condition at the base of the shoot. We compare the water uptake efficiency of three types of root system architectures of a maize plant. Two are actual architectures from genotypes showing significant differences regarding the internodal distance, the root growth rate and the insertion angle of their primary roots. The third one is an ideotype according to Lynch of the maize plant designed to perform better in one dry environment. We generated with RootBox five repetitions of these three root systems with the same total root volume and simulated two drought scenarios at the flowering stage (lack of water at the top or at the bottom of the soil domain). We did these simulations for two distinct distributions of local conductivities of root

  17. Use of plant woody species electrical potential for irrigation scheduling.

    Science.gov (United States)

    Ríos-Rojas, Liliana; Morales-Moraga, David; Alcalde, José A; Gurovich, Luis A

    2015-01-01

    The electrical response of plants to environmental stimuli can be measured and quantitatively related to the intensity of several stimulating sources, like temperature, solar radiation, soil water content, evapotranspiration rates, sap flow and dendrometric cycles. These relations can be used to assess the influence of different environmental situations on soil water availability to plants, defined as a steady state condition between leaf transpirative flow and soil water flow to plant roots. A restricted soil water flow due to soil dryness can trigger water stress in plants, if the atmospheric evaporative demand is high, causing partial stomata closure as a physiological response to avoid plant dehydration; water stressed and unstressed plants manifest a differential electrical response. Real time plant electrical response measurements can anticipate actions that prevent the plant reaching actual stress conditions, optimizing stomata gas exchange and photosynthetic rates. An electrophysiological sensor developed in this work, allows remote real-time recording information on plant electrical potential (EP) in the field, which is highly related to EP measurements obtained with a laboratory Keithley voltmeter sensor used in an highly controlled experimental setup. Our electrophysiological sensor is a wireless, autonomous devise, which transmits EP information via Internet to a data server. Using both types of sensors (EP electrodes with a Keithley voltmeter and the electrophysiological sensor), we measured in real time the electrical responses of Persea americana and Prunus domestica plants, to induced water deficits. The differential response for 2 scenarios: irrigation and water restriction is identified by a progressive change in slope on the daily maximal and minimal electric signal values in stressed plants, and a zero-slope for similar signals for well-watered plants. Results show a correspondence between measured signals obtained by our electrophysiological

  18. Dissolved Organic Nitrogen Inputs from Wastewater Treatment Plant Effluents Increase Responses of Planktonic Metabolic Rates to Warming.

    Science.gov (United States)

    Vaquer-Sunyer, Raquel; Conley, Daniel J; Muthusamy, Saraladevi; Lindh, Markus V; Pinhassi, Jarone; Kritzberg, Emma S

    2015-10-06

    Increased anthropogenic pressures on coastal marine ecosystems in the last century are threatening their biodiversity and functioning. Global warming and increases in nutrient loadings are two major stressors affecting these systems. Global warming is expected to increase both atmospheric and water temperatures and increase precipitation and terrestrial runoff, further increasing organic matter and nutrient inputs to coastal areas. Dissolved organic nitrogen (DON) concentrations frequently exceed those of dissolved inorganic nitrogen in aquatic systems. Many components of the DON pool have been shown to supply nitrogen nutrition to phytoplankton and bacteria. Predictions of how global warming and eutrophication will affect metabolic rates and dissolved oxygen dynamics in the future are needed to elucidate their impacts on biodiversity and ecosystem functioning. Here, we experimentally determine the effects of simultaneous DON additions and warming on planktonic community metabolism in the Baltic Sea, the largest coastal area suffering from eutrophication-driven hypoxia. Both bacterioplankton community composition and metabolic rates changed in relation to temperature. DON additions from wastewater treatment plant effluents significantly increased the activation energies for community respiration and gross primary production. Activation energies for community respiration were higher than those for gross primary production. Results support the prediction that warming of the Baltic Sea will enhance planktonic respiration rates faster than it will for planktonic primary production. Higher increases in respiration rates than in production may lead to the depletion of the oxygen pool, further aggravating hypoxia in the Baltic Sea.

  19. Response of insect relative growth rate to temperature and host-plant phenology: estimation and validation from field data.

    Science.gov (United States)

    Ciss, Mamadou; Parisey, Nicolas; Fournier, Gwenaëlle; Taupin, Pierre; Dedryver, Charles-Antoine; Pierre, Jean-Sébastien

    2014-01-01

    Between 1975 to 2011, aphid Relative Growth Rates (RGR) were modelled as a function of mean outdoor temperature and host plant phenology. The model was applied to the grain aphid Sitobion avenae using data on aphid counts in winter wheat at two different climate regions in France (oceanic climate, Rennes (western France); continental climate, Paris). Mean observed aphid RGR was higher in Paris compared to the Rennes region. RGR increased with mean temperature, which is explained by aphid reproduction, growth and development being dependent on ambient temperature. From the stem extension to the heading stage in wheat, there was either a plateau in RGR values (Rennes) or an increase with a maximum at heading (Paris) due to high intrinsic rates of increase in aphids and also to aphid immigration. From the wheat flowering to the ripening stage, RGR decreased in both regions due to the low intrinsic rate of increase in aphids and high emigration rate linked to reduced nutrient quality in maturing wheat. The model validation process showed that the fitted models have more predictive power in the Paris region than in the Rennes region.

  20. The PLASTID DIVISION1 and 2 Components of the Chloroplast Division Machinery Determine the Rate of Chloroplast Division in Land Plant Cell Differentiation

    National Research Council Canada - National Science Library

    Kumiko Okazaki; Yukihiro Kabeya; Kenji Suzuki; Toshiyuki Mori; Takanari Ichikawa; Minami Matsui; Hiromitsu Nakanishi; Shin-Ya Miyagishima

    2009-01-01

    .... By contrast, land plants evolved cell and chloroplast differentiation systems in which the size and number of chloroplasts change along with their respective cellular function by regulation of the division rate...

  1. The ecological effects of different loading rates of metalaxyl on microbial biomass in unplanted and planted soils under field conditions

    Directory of Open Access Journals (Sweden)

    M. Mansourzadeh

    2016-05-01

    Full Text Available Fungicides are most widely used pesticides in Iran and the world. Application of fungicides may affect the populations and activity of soil microorganisms, particularly fungi, with a consequence for soil fertility and crop growth. In the current study, the effects of different levels of metalaxyl on soil microbial biomass carbon (C and nitrogen (N, microbial biomass C/N ratio and metabolic quotient under field conditions were assessed. Two levels of metalaxyl (30 and 60 kg.ha-1 were applied in planted soils with corn and unplanted calcareous soils, using a split-plots experiment in a completely randomized design with three replications. The C and N contents in soil microbial biomass as well as metabolic quotient were measured at 30 and 90 days after the onset of the experiment. Results showed that in cultivated soils metalaxyl application at 30 kg.ha-1 increased (15-80% significantly (p≤0.01 the amounts of microbial biomass C and N at both intervals (except microbial biomass C at 90 days compared to the control soil (0 kg.ha-1, while in uncultivated soils both microbial biomass C and N reduced by almost 1-34%. Microbial biomass C/N ratios in unplanted soils decreased (15 and 53% with increasing loading rates of metalaxyl, without a clear effect in cultivated soils. On the other hand, metabolic quotient values reduced (48% at 30 and 60 kg.ha-1 metalaxyl in corn-cultivated soils when compared to untreated soils while in uncultivated soils metalaxyl rate at 30 kg.a-1 had the greatest values at 30 days, and increased with increasing the levels of metalaxyl at 90 days. In summary, application of metalaxyl can either reduce or increase soil biological indices, and the direction and changes are depended upon the application rate of metalaxyl, time elapsed since metalaxyl application and the presence or absence of plant.

  2. Engineering the use of green plants to reduce produced water disposal volume.

    Energy Technology Data Exchange (ETDEWEB)

    Hinchman, R.; Mollock, G. N.; Negri, M. C.; Settle, T.

    1998-01-29

    In 1990, the Laboratory began an investigation into biological approaches for the reduction of water produced from oil and gas wells. In the spring of 1995, the Company began an on-site experiment at an oil/gas lease in Oklahoma using one of these approaches. The process, known as phytoremediation, utilizes the ability of certain salt tolerant plants to draw the produced water through their roots, transpire the water from their leaves, and thereby reduce overall water disposal volumes and costs. At the Company experimental site, produced water flows through a trough where green plants (primarily cordgrass) have been planted in pea gravel. The produced water is drawn into the plant through its roots, evapotranspirates and deposits a salt residue on the plant leaves. The plant leaves are then harvested and used by a local rancher as cattle feed. The produced water is tested to assure it contains nothing harmful to cattle. In 1996, the Company set up another trough to compare evaporation rates using plants versus using an open container without plants. Data taken during all four seasons (water flow rate, temperature, pH, and conductivity) have shown that using plants to evapotranspirate produced water is safe, more cost effective than traditional methods and is environmentally sound.

  3. Silicon alleviates drought stress of rice plants by improving plant water status, photosynthesis and mineral nutrient absorption.

    Science.gov (United States)

    Chen, Wei; Yao, Xiaoqin; Cai, Kunzheng; Chen, Jining

    2011-07-01

    Drought is a major constraint for rice production in the rainfed lowlands in China. Silicon (Si) has been verified to play an important role in enhancing plant resistance to environmental stress. Two near-isogenic lines of rice (Oryza sativa L.), w-14 (drought susceptible) and w-20 (drought resistant), were selected to study the effects of exogenous Si application on the physiological traits and nutritional status of rice under drought stress. In wet conditions, Si supply had no effects on growth and physiological parameters of rice plants. Drought stress was found to reduce dry weight, root traits, water potential, photosynthetic parameters, basal quantum yield (F(v)/F(0)), and maximum quantum efficiency of PSII photochemistry (F(v)/F(m)) in rice plants, while Si application significantly increased photosynthetic rate (Pr), transpiration rate (Tr), F(v)/F(0), and F(v)/F(m) of rice plants under drought stress. In addition, water stress increased K, Na, Ca, Mg, Fe content of rice plants, but Si treatment significantly reduced these nutrient level. These results suggested that silicon application was useful to increase drought resistance of rice through the enhancement of photochemical efficiency and adjustment of the mineral nutrient absorption in rice plants.

  4. Modeling Potential Impacts of Planting Palms or Tree in Small Holder Fruit Plantations on Ecohydrological Processes in the Central Amazon

    Directory of Open Access Journals (Sweden)

    Norbert Kunert

    2015-07-01

    Full Text Available Native fruiting plants are widely cultivated in the Amazon, but little information on their water use characteristics can be found in the literature. To explore the potential impacts of plantations on local to regional water balance, we studied plant water use characteristics of two native fruit plants commonly occurring in the Amazon region. The study was conducted in a mixed fruit plantation containing a dicot tree species (Cupuaçu, Theobroma grandiflorum and a monocot palm species (Açai, Euterpe oleracea close to the city of Manaus, in the Central Amazon. Scaling from sap flux measurements, palms had a 3.5-fold higher water consumption compared to trees with a similar diameter. Despite the high transpiration rates of the palms, our plantation had only one third of the potential water recycling capacity of natural forests in the area. Converting natural forest into such plantations will thus result in significantly higher runoff rates.

  5. Three dimensional free convection couette flow with transpiration cooling

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Free convection flow between two vertical parallel plates with transverse sinusoidal injection of the fluid at the stationary plate and its corresponding removal by constant suction through the plate in uniform motion has been analyzed. Due to this type of injection velocity, the flow becomes three-dimensional. Analytical expressions for the velocity, temperature, skin friction and rate of heat transfer were obtained. The important characteristics of the problem, namely the skin friction and the rate of heat transfer are discussed in detail with the help of graphs.

  6. Use of the transpiration method to study polonium evaporation from liquid lead-bismuth eutectic at high temperature

    Energy Technology Data Exchange (ETDEWEB)

    Prieto, Borja Gonzalez [SCKCEN (Belgian Nuclear Research Centre), Mol (Belgium); KU Leuven, Heverlee (Belgium). Centre of Surface Chemistry and Catalysis; Marino, Alessandro [SCKCEN (Belgian Nuclear Research Centre), Mol (Belgium); Vrije Universiteit Brussel, Elsene (Belgium); Lim, Jun; Rosseel, Kris; Bosch, Joris van den; Aerts, Alexander [SCKCEN (Belgian Nuclear Research Centre), Mol (Belgium); Martens, Johan [KU Leuven, Heverlee (Belgium). Centre of Surface Chemistry and Catalysis; Rizzi, Matthias; Neuhausen, Joerg [Paul Scherrer Institute, Villigen (Switzerland). Lab. for Radio- and Environmental Chemistry

    2014-07-01

    Qualitative and quantitative understanding of Po volatilization under different conditions is of key importance for safety assessments of lead-bismuth eutectic (LBE) based nuclear reactors, spallation targets and accelerator driven systems. In this work we explore the possibilities of the transpiration method in combination with simple models to study the equilibrium and kinetics of Po evaporation from highly diluted solutions in lead-bismuth eutectic between 600 and 1000 C in Ar/5% H{sub 2} and Ar. On the basis of evaporation experiments at various carrier gas flow rates, we identified the conditions of vapor saturation allowing the determination of equilibrium constants. From the limiting behavior at high flow rates, values for the maximal evaporation rate of Po from LBE were estimated. Measurements of evaporation as a function of time were consistent with the assumption that polonium dissolved in LBE obeys Henry's law. A theoretical analysis furthermore suggested that diffusion of polonium in LBE was not a rate limiting factor for evaporation under vapor saturation conditions. Newly determined values for the Henry constant of Po in LBE between 600 and 1000 C were consistent with previously derived correlations.

  7. Carbon Isotope Discrimination is not Correlated with Transpiration Efficiency in Three Cool-Season Grain Legumes (Pulses)

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The carbon Isotope discrimination (δ13C) of leaves has been shown to be correlated with the transpiration efficiency of leaves in a wide range of species. This has led to δ13C being used in breeding programs to select for improved transpiration efficiency. The correlation between δ13C and transpiration efficiency was determined under well-watered conditions during the vegetative phase In six genotypes of lentil (Lens culinaris Medikus), six genotypes of chickpea (Cicer arietinum L.) and 10 cultivars of narrow-leafed lupin (Lupinus angustifolius L.). Biomass (dry matter) accumulation and water use (transpiration)varied among the genotypes in all three species and transpiration efficiency was 40% to 75% higher In the most efficient compared with the least efficient genotypes. However, δ13C and transpiration efficiency were not significantly correlated in any of the species. This suggests that the δ13C technique cannot be used In selection for transpiration efficiency in the three grain legumes (pulses) studied.

  8. Heterogeneity of competition at decameter scale: patches of high canopy leaf area in a shade-intolerant larch stand transpire less yet are more sensitive to drought.

    Science.gov (United States)

    Xiong, Wei; Oren, Ram; Wang, Yanhui; Yu, Pengtao; Liu, Hailong; Cao, Gongxiang; Xu, Lihong; Wang, Yunni; Zuo, Haijun

    2015-05-01

    offer potential explanations to the observed phenomenon. Our results demonstrate that spatial variation of L at decameter scale, even within relatively homogeneous, single-species, even-aged stands, can produce large variation of transpiration, soil moisture and biomass production and should be considered in 1-D soil-plant-atmosphere models.

  9. The activity of ascorbic acid and catechol oxidase, the rate of photosynthesis and respiration as related to plant organs, stage of development and copper supply

    Directory of Open Access Journals (Sweden)

    St. Łyszcz

    2015-06-01

    Full Text Available Some experiments were performed to investigate the physiological role of copper in oat and sunflower and to recognize some effects of copper deficiency. Oat and sunflower plants were grown in pots on a peat soil under copper deficiency conditions (–Cu or with the optimal copper supply (+Cu. In plants the following measurements were carried out: 1 the activity of ascorbic acid oxidase (AAO and of catechol oxidase (PPO in different plant organs and at different stages of plant development, 2 the activity and the rate of photosynthesis, 3 the activity of RuDP-carboxylase, 4 the intensity of plant respiration. The activity of AAO and of PPO, and also the rate and the activity of photosynthesis were significantly lower under conditions of copper deficiency. The activity of both discussed oxidases depended on: 1 the plant species, 2 plant organs, 3 stage of plant development. Copper deficiency caused decrease of the respiration intensity of sunflower leaves but it increased to some extent the respiration of oat tops. Obtained results are consistent with the earlier suggestion of the authors that the PPO activity in sunflower leaves could be a sensitive indicator of copper supply of the plants, farther experiments are in progress.

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

    Science.gov (United States)

    Burkhardt, J; Pariyar, S

    2016-01-01

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

  11. Background dose-rates to reference animals and plants arising from exposure to naturally occurring radionuclides in aquatic environments

    Energy Technology Data Exchange (ETDEWEB)

    Hosseini, A; Brown, J E; Thoerring, H [Norwegian Radiation Protection Authority (Norway); Beresford, N A [Centre for Ecology and Hydrology, Lancaster Environment Centre, Bailrigg, Lancaster LA1 4AP (United Kingdom); Jones, D G [British Geological Society, Keyworth, Nottingham NG12 5GG (United Kingdom); Phaneuf, M [Canadian Nuclear Safety Commission (Canada); Yankovich, T [AREVA Resources Canada Inc. (Canada)

    2010-06-15

    In order to put dose-rates derived in environmental impact assessments into context, the International Commission on Radiological Protection (ICRP) has recommended the structuring of effects data according to background exposure levels. The ICRP has also recommended a suite of reference animals and plants (RAPs), including seven aquatic organisms, for use within their developing framework. In light of these propositions, the objective of this work was to collate information on activity concentrations of naturally occurring primordial radionuclides for marine and freshwater ecosystems and apply appropriate dosimetry models to derive absorbed dose-rates. Although coverage of activity concentration data is comprehensive for sediment and water, few, or in some cases no, data were found for some RAPs, e.g. for frogs (Ranidae) and freshwater grasses (Poaceae) for most radionuclides. The activity concentrations for individual radionuclides in both organisms and their habitat often exhibit standard deviations that are substantially greater than arithmetic mean values, reflecting large variability in activity concentrations. To take account of variability a probabilistic approach was adopted. The dominating radionuclides contributing to exposure in the RAPs are {sup 40}K, {sup 210}Po and {sup 226}Ra. The mean unweighted and weighted dose-rates for aquatic RAPs are in the ranges 0.07-0.39 {mu}Gy h{sup -1} and 0.37-1.9 {mu}Gy h{sup -1} respectively.

  12. Hydraulic resistance partitioning between shoot and root system and plant water status of Haloxyolon ammodendron growing at sites of contrasting soil texture

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Hydraulic resistance components and water relations were studied on Haloxyolon ammoden-dron,a small xeric tree,growing at sites significantly differed in soil texture.Soil water content,leaf water potential(ψl),xylem water potential(ψx),root water potential(ψroot),leaf transpiration rate(TR) and stomatal conductance(gs) were measured at the two sites during the growing season of 2005 and 2006.Leaf spe-cific hydraulic resistance(Rplant) during the whole growing season,hydraulic resistance of plants(Rp),shoots(Rshoot) and roots(Rroot) in the August of both years were calculated and expressed on leaf area basis.The results showed the proportion of the hydraulic resistance of the aerial part(Rshoot) to the Rp was the same to the proportion of the hydraulic resistance of the soil part(Rroot) to the Rp,indicating that both parts were equivalent important to plant water hydraulic system from soil to leaf.Positive significant corre-lations were found between Rp and Rroot,suggesting that root hydraulics resistance was a major determinant of plant hydraulic resistance(Rp) and transpiration rate.The integrated effect of stomatal control,hy-draulic regulation and morphology adjustment enabled plants at heavy soil site surviving the extreme water deficit period.

  13. Soil- and plant- water uptake in saline environments and their consequences to plant adaptation in fluctuating climates

    Science.gov (United States)

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

    2010-12-01

    Ecological processes determining plant colonization are quite peculiar and competition among different species is governed by a set of unique adaptations to stress conditions caused by drought, hypoxic or hyper-saline conditions. These adaptations and possible positive feedbacks often lead to the formation of patterns of vegetation colonization and spatial heterogeneity (zonation), and play a primary role in the stabilization of sediments. It is these issues that frame the scope of this study. The main objective of this work is to track one of the fundamental pathways between plant adaptation (quantified in terms of physiological and ecological attributes such as leaf area or root density profile) and feedbacks (quantified by plant-mediated alterations to water availability and salinity levels): root water uptake. Because root-water uptake is the main conduit connecting transpiring leaves to reservoirs of soil water, the means by which salinity modifies the processes governing its two end-points and any two-way interactions between them serves as a logical starting point. Salinity effects on leaf transpiration and photosynthesis are first explored via stomatal optimization principles that maximize carbon gain at a given water loss for autonomous leaves. Salinity directly affects leaf physiological attributes such as mesophyll conductance and photosynthetic parameters and hence over-all conductance to transpiration as well as different strategies to cope with the high salinity (e.g. through salt seclusion, compartmentation and osmotic adjustments). A coupled model of subsurface flow based on a modified Richards’ equation that accounts for the effects of increasing salinity, anaerobic conditions, water stress and compensation factors is developed. Plant water uptake is considered as a soil moisture sink term with a potential rate dictated by the carbon demands of the leaves, and an actual rate that accounts for both - hydraulic and salinity limitations. Using this

  14. Torrefaction of invasive alien plants: Influence of heating rate and other conversion parameters on mass yield and higher heating value.

    Science.gov (United States)

    Mundike, Jhonnah; Collard, François-Xavier; Görgens, Johann F

    2016-06-01

    With the aim of controlling their proliferation, two invasive alien plants, Lantana camara (LC) and Mimosa pigra (MP), both widespread in Africa, were considered for torrefaction for renewable energy applications. Using thermogravimetric analysis, the influence of heating rate (HR: 2.18-19.82°Cmin(-1)) together with variable temperature and hold time on char yield and HHV (in a bomb calorimeter) were determined. Statistically significant effects of HR on HHV with optima at 10.5°Cmin(-1) for LC and 20°Cmin(-1) for MP were obtained. Increases of HHV up to 0.8MJkg(-1) or energy yield greater than 10%, together with a 3-fold reduction in torrefaction conversion time could be achieved by optimisation of HR. Analysis of the torrefaction volatiles by TG-MS showed that not only hemicelluloses, but also lignin conversion, could influence the optimum HR value.

  15. Relationship between stomatal behavior and characteristics of photosynthesis and transpiration of Adenophora Iobophylla and A. potaninii at different altitudes

    Institute of Scientific and Technical Information of China (English)

    Ma Shu rong; Yan Xiufeng; Zu Yuangang

    1999-01-01

    The photosynthesis and transpiration characteristics ofAdenophora Iobophylla and A. potaninii, as well as stomatal behavior such as stomatal size, stomatal density, stomatal open and stomatal conductivity were measured at different altitudes. The relationship between the photosynthesis and transpiration characteristics and the stomatal behavior was analysed by correlation coefficient and path coefficient analysis with altitude changes.The results showed that the influences of stomatal behavior were not evident on the photosynthesis and transpiration characteristics of A. Lobophylla, but evident on that of A. potaninii.

  16. Some Physiological Processes Related to Water Use Efficiency of Higher Plants

    Institute of Scientific and Technical Information of China (English)

    GUO Shi-wei; ZHOU Yi; SONG Na; SHEN Qi-rong

    2006-01-01

    Water use efficiency (WUE) of higher plants is of vital importance in the dry-land agricultural ecosystem in terms of the development of water-saving agriculture. Of all the approaches used to improve WUE, the intrinsic water use efficiency (WUET, the ratio of CO2 assimilation rate to transpiration rate) can be a right index, as the variation of WUET is correlated with the physiological and biochemical processes of higher plants. The measurements of leaf gas exchange and carbon isotope discrimination (D13C) are the two ways to detect the variation in WUET. This article reviewed some physiological processes related to WUET, including the relationship between CO2 assimilation and stomatal conductance and WUEr and water absorption. The relationship between WUE and aquaporin and the yield are discussed as well.

  17. Effect of Pot Size on Various Characteristics Related to Photosynthetic Matter Production in Soybean Plants

    Directory of Open Access Journals (Sweden)

    Minobu Kasai

    2012-01-01

    Full Text Available Despite the wide uses of potted plants, information on how pot size affects plant photosynthetic matter production is still considerably limited. This study investigated with soybean plants how transplantation into larger pots affects various characteristics related to photosynthetic matter production. The transplantation was analyzed to increase leaf photosynthetic rate, transpiration rate, and stomatal conductance without affecting significantly leaf intercellular CO2 concentration, implicating that the transplantation induced equal increases in the rate of CO2 diffusion via leaf stomata and the rate of CO2 fixation in leaf photosynthetic cells. Analyses of Rubisco activity and contents of a substrate (ribulose-1,5-bisphosphate (RuBP for Rubisco and total protein in leaf suggested that an increase in leaf Rubisco activity, which is likely to result from an increase in leaf Rubisco content, could contribute to the transplantation-induced increase in leaf photosynthetic rate. Analyses of leaf major photosynthetic carbohydrates and dry weights of source and sink organs revealed that transplantation increased plant sink capacity that uses leaf starch, inducing a decrease in leaf starch content and an increase in whole plant growth, particularly, growth of sink organs. Previously, in the same soybean species, it was demonstrated that negative correlation exists between leaf starch content and photosynthetic rate and that accumulation of starch in leaf decreases the rate of CO2 diffusion within leaf. Thus, it was suggested that the transplantation-induced increase in plant sink capacity decreasing leaf starch content could cause the transplantation-induced increase in leaf photosynthetic rate by inducing an increase in the rate of CO2 diffusion within leaf and thereby substantiating an increase in leaf Rubisco activity in vivo. It was therefore concluded that transplantation of soybean plants into larger pots attempted in this study increased the

  18. Exposure to air pollution near a steel plant is associated with reduced heart rate variability: a randomised crossover study.

    Science.gov (United States)

    Shutt, Robin H; Kauri, Lisa Marie; Weichenthal, Scott; Kumarathasan, Premkumari; Vincent, Renaud; Thomson, Errol M; Liu, Ling; Mahmud, Mamun; Cakmak, Sabit; Dales, Robert

    2017-01-28

    Epidemiological studies have shown that as ambient air pollution (AP) increases the risk of cardiovascular mortality also increases. The mechanisms of this effect may be linked to alterations in autonomic nervous system function. We wished to examine the effects of industrial AP on heart rate variability (HRV), a measure of subtle changes in heart rate and rhythm representing autonomic input to the heart. Sixty healthy adults were randomized to spend five consecutive 8-h days outdoors in one of two locations: (1) adjacent to a steel plant in the Bayview neighbourhood in Sault Ste Marie Ontario or (2) at a College campus, several kilometers from the plant. Following a 9-16 day washout period, participants spent five consecutive days at the other site. Ambient AP levels and ambulatory electrocardiogram recordings were collected daily. HRV analysis was undertaken on a segment of the ambulatory ECG recording during a 15 min rest period, near the end of the 8-h on-site day. Standard HRV parameters from both time and frequency domains were measured. Ambient AP was measured with fixed site monitors at both sites. Statistical analysis was completed using mixed-effects models. Compared to the College site, HRV was statistically significantly reduced at the Bayview site by 13% (95%CI 3.6,19.2) for the standard deviation of normal to normal, 8% (95%CI 0.1, 4.9) for the percent normal to normal intervals differing by more than 50 ms, and 15% (95%CI 74.9, 571.2) for low frequency power. Levels of carbon monoxide, sulphur dioxide, nitrogen dioxide, and fine and ultrafine particulates were slightly, but statistically significantly, elevated at Bayview when compared to College. Interquartile range changes in individual air pollutants were significantly associated with reductions in HRV measured on the same day. The patterns of effect showed a high degree of consistency, with nearly all pollutants significantly inversely associated with at least one measure of HRV. The significant

  19. Guidance proposal for using available DegT50 values for estimation of degradation rates of plant protection products in Dutch surface water and sediment

    NARCIS (Netherlands)

    Boesten, J.J.T.I.; Adriaanse, P.I.; Horst, ter M.M.S.; Tiktak, A.; Linden, van der A.M.A.

    2014-01-01

    The degradation rate of plant protection products and their transformation products in surface water and sediment may influence their concentrations in Dutch surface water. Therefore the estimation of these rates may be an important part of the assessment of the exposure of aquatic organisms. We

  20. Canopy-scale biophysical controls on transpiration and evaporation in the Amazon Basin

    DEFF Research Database (Denmark)

    Mallick, Kaniska; Trebs, Ivonne; Bøgh, Eva

    2016-01-01

    Canopy and aerodynamic conductances (gC and gA) are two of the key land surface biophysical variables that control the land surface response of land surface schemes in climate models. Their representation is crucial for predicting transpiration (λET) and evaporation (λEE) flux components of the t......Canopy and aerodynamic conductances (gC and gA) are two of the key land surface biophysical variables that control the land surface response of land surface schemes in climate models. Their representation is crucial for predicting transpiration (λET) and evaporation (λEE) flux components...... is attributed to relatively low soil water availability as compared to the rainforests, likely due to differences in rooting depth between the two systems. Evaporation was significantly influenced by gA for all the PFTs and across all wetness conditions. Our analytical framework logically captures the responses...

  1. Use of Several Plant Materials and Chemicals to inhibit Soil Urease Activity and Increase Nitrogen Recovery Rate of Urea by Plant

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Effects of residues of 9 plants, lemon eucalyptus (Eucalyptus citriodora Hook., P1), robust eucalyptus (E. robusta Smith, P2), Nepal camphortree (Cinnamomum glanduliferum (Wall.) Nees, P3), tea (Camellia sinensis (Linn.) O. Ktze. f., P4), oleander (Nerium indicum Mill, P5), rape (Brassica campestris L., P6),Chinese tallow tree (Sapium sebiferum L., P7), tung (Vernicia fordii (Hemsl.), P8), and croton (Croton tiglium L., P9), 7 chemicals, boric acid (C1), borax (C2), oxalic acid (C3), sodium oxalite (C4), sodium dihydrogen phosphate (C6), sodium silicate (C7) and sodium citrate (C8), and a natural organic substance,humic acid (C5), on urease activity of a neutral purple soil and recovery of urea nitrogen by maize were studied through incubation and pot experiments. Hydroquinone (HQ) was applied as the reference inhibitor. After incubation at 37 ℃ for 24 h, 7 inhibitors with higher ability to inhibit urease activity were selected and then incubated for 14 days at 25 ℃. Results of the incubation experiments showed that soil urease activity was greatly inhibited by them, and the inhibition effect followed an order of P2>P4>C3>C2>P3>C1>HQ>P1.The 7 selected materials reduced the accumulative amounts of N released from urea and the maximum urease activity by 11.7%~28.4% and 26.7%~39.7%, respectively, and postponed the N release peak by 2~4 days in the incubation period of 14 days under constant temperature, as compared to the control (no inhibitor).In the pot experiment with the 7 materials at two levels of addition, low (L) and high (H), the C1 (H), C3(H), C1 (L), P4 (L) and C2 (L) treatments could significantly increase the dry weights of the aboveground parts and the total biomass of the maize plants and the apparent recovery rate of urea-N was increased by 6.3%~32.4% as compared to the control (no hibitor).

  2. Relative importance of an arbuscular mycorrhizal fungus (Rhizophagus intraradices) and root hairs in plant drought tolerance.

    Science.gov (United States)

    Li, Tao; Lin, Ge; Zhang, Xin; Chen, Yongliang; Zhang, Shubin; Chen, Baodong

    2014-11-01

    Both arbuscular mycorrhizal (AM) fungi and root hairs play important roles in plant uptake of water and mineral nutrients. To reveal the relative importance of mycorrhiza and root hairs in plant water relations, a bald root barley (brb) mutant and its wild type (wt) were grown with or without inoculation of the AM fungus Rhizophagus intraradices under well-watered or drought conditions, and plant physiological traits relevant to drought stress resistance were recorded. The experimental results indicated that the AM fungus could almost compensate for the absence of root hairs under drought-stressed conditions. Moreover, phosphorus (P) concentration, leaf water potential, photosynthetic rate, transpiration rate, stomatal conductance, and water use efficiency were significantly increased by R. intraradices but not by root hairs, except for shoot P concentration and photosynthetic rate under the drought condition. Root hairs even significantly decreased root P concentration under drought stresses. These results confirm that AM fungi can enhance plant drought tolerance by improvement of P uptake and plant water relations, which subsequently promote plant photosynthetic performance and growth, while root hairs presumably contribute to the improvement of plant growth and photosynthetic capacity through an increase in shoot P concentration.

  3. Effects of SO/sub 2/ dosage kinetics and exposure frequency on photosynthesis and transpiration of kidney beans (Phaseolus vulgaris L. )

    Energy Technology Data Exchange (ETDEWEB)

    McLaughlin, S.B.; Shriner, D.S.; McConathy, R.K.; Mann, L.K.

    1979-01-01

    The effects of variations in SO/sub 2/ dosage kinetics on bean plants (Phaseolus vulgaris L. red kidney) were studied at SO/sub 2/ levels equal to or below the current secondary ambient air quality standard. Response of photosynthesis, transpiration and growth were measured to evaluate the extent and duration of effects following repeated treatment at weekly (Experiment I) and daily (Experiment II) intervals. Depression of photosynthesis was the most consistent response observed. Transpiration was either stimulated or depressed by SO/sub 2/ concentrations which reduced photosynthesis. This effect indicates a probable biochemical rather than stomatal basis for observed photosynthetic depressions noted in these experiments. Increasing the peak:mean concentration ratio from 1.0 to 1.7 during exposure had no obvious effect on short-term photosynthetic response but caused apparent stimulation of photosynthesis one day later. Increasing the peak:mean ratio from 1.0 to 6.0 caused a threefold average greater depression of short-term photosynthetic response even though the 3 hr av. concentration was reduced by 25% (0.50-0.37). Residual effects from this treatment were generally small on the day after exposure. No strong evidence was obtained to indicate that plants were sensitized to SO/sub 2/-induced suppression of photosynthesis by previous exposure to SO/sub 2/. Predisposition was not apparent when exposures were repeated at weekly or daily intervals. Visible foliar injury did not occur. Analysis of harvest data at the end of these experiments indicated that plants could undergo a repeated short-term (1 day) cycle of photosynthetic inhibition and still retain an essentially unimpaired capacity for growth during a subsequent recovery period. When exposures were spaced a week apart, some indication of a residual effect on growth, particularly with the highest peak:mean ratio (6.0), was apparent. 26 references, 6 figures, 2 tables.

  4. A multiscale Bayesian data integration approach for mapping air dose rates around the Fukushima Daiichi Nuclear Power Plant.

    Science.gov (United States)

    Wainwright, Haruko M; Seki, Akiyuki; Chen, Jinsong; Saito, Kimiaki

    2017-02-01

    This paper presents a multiscale data integration method to estimate the spatial distribution of air dose rates in the regional scale around the Fukushima Daiichi Nuclear Power Plant. We integrate various types of datasets, such as ground-based walk and car surveys, and airborne surveys, all of which have different scales, resolutions, spatial coverage, and accuracy. This method is based on geostatistics to represent spatial heterogeneous structures, and also on Bayesian hierarchical models to integrate multiscale, multi-type datasets in a consistent manner. The Bayesian method allows us to quantify the uncertainty in the estimates, and to provide the confidence intervals that are critical for robust decision-making. Although this approach is primarily data-driven, it has great flexibility to include mechanistic models for representing radiation transport or other complex correlations. We demonstrate our approach using three types of datasets collected at the same time over Fukushima City in Japan: (1) coarse-resolution airborne surveys covering the entire area, (2) car surveys along major roads, and (3) walk surveys in multiple neighborhoods. Results show that the method can successfully integrate three types of datasets and create an integrated map (including the confidence intervals) of air dose rates over the domain in high resolution. Moreover, this study provides us with various insights into the characteristics of each dataset, as well as radiocaesium distribution. In particular, the urban areas show high heterogeneity in the contaminant distribution due to human activities as well as large discrepancy among different surveys due to such heterogeneity.

  5. Effect of the plant Azolla pinnata on survival, growth rate, fecundity and hatchability of egg-masses of Biomphalaria alexandrina snails.

    Science.gov (United States)

    Abdel Hafez, A M; Zidan, Z H; Abdel-Megeed, M I; el-Emam, M A; Ragab, F M; el-Deeb, F A

    1997-12-01

    Data indicated that Azolla pinnata plants variously reduce the growth rate of Biomphalaria alexandrina snails expressed as net increase in shell diameter (direct or indirect exposure). The plant density played an important role in this respect. The higher the plant density was the lower the growth rate and vice versa. Too, indirect exposure of newly hatched B. alexandrina resulted from exposed treated eggs reduced the growth rate of these snails. Data revealed that direct and/or indirect exposure to the abnormal high density (50,000 plants/L) resulted in complete kill of B. alexandrina snails after two weeks from continuous exposure. Snails exposed directly to Azolla at 50,000 and 25,000 plants/L failed to lay eggs. On the other hand, sanils exposed to 10,000 plants/L laid few eggs, resulted in low reproductive rate (57.94) compared with unexposed ones (110.6). The same trend of results was recorded with hatchability of Biomphalaria eggs.

  6. [Effects of nitrogen fertilization rate and planting density on cotton biomass and nitrogen accumulation in extremely early mature cotton region of Northeast China].

    Science.gov (United States)

    Wang, Zi-Sheng; Xu, Min; Zhang, Guo-Wei; Jin, Lu-Lu; Shan, Ying; Wu, Xiao-Dong; Zhou, Zhi-Guo

    2011-12-01

    Taking two cotton cultivars Liaomian 19 and NuCOTN 33B with different growth periods as test materials, a field experiment was conducted to study the effects of different nitrogen fertilization rates (0, 240 and 480 kg N x hm(-2)) and different planting densities (75000, 97500 and 120000 plants x hm(-2)) on the cotton biomass, nitrogen accumulation, and accumulative nitrogen utilization in the planting region of extremely early mature cotton in Northeast China. The dynamics of cotton biomass and nitrogen accumulation of the two cultivars with their growth process followed Logistic model. Both nitrogen fertilization rate and planting density had significant effects on the cotton nitrogen accumulation dynamics and the cotton yield and quality. In all treatments, the beginning time of rapid accumulation of nitrogen was about 13 d earlier than that of biomass. In treatment plant density 97500 plants x hm(-2) and nitrogen fertilization rate 240 kg x hm(-2), the eigenvalues of the dynamic accumulation models of nitrogen and biomass for the two cultivars were most harmonious, lint yield was the highest, fiber quality was the best, and accumulative nitrogen utilization efficiency was the highest. In the study region, the earlier beginning time of rapid accumulation of nitrogen and biomass and their higher accumulation rates were benefit to the formation of higher cotton yield.

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

    Science.gov (United States)

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

    2007-01-01

    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.

  8. Kinetic Theory of Thermal Transpiration and Mechanocaloric Effects: Flow of Rarefied Polyatomic Gases.

    Science.gov (United States)

    Lo, Sui-Sang

    The polyatomic gas model equations developed by Hansen and Morse were used in the linearized Wang-Chang and Uhlenbeck equation to study the thermal transpiration and mechanocaloric effects in various geometries with different boundary conditions. The phenomenological coefficients for mass and energy flows at all degrees of rarefaction are reported. It is shown, on a theoretical basis, that the thermal transpiration effect ratio has a strong dependence on f(,tr), the translational Eucken factor, and only a weak dependence on f(,tr), the total Eucken factor. The cross coefficients (,MQ) = (,QM) for all calculations but the energy flux near the wall was found negative for inverse Knudsen numbers greater than 3. Flow of polyatomic gases was studied in a long cylindrical tube with the Maxwell's diffuse scattering boundary conditions. Experimental thermal transpiration effect ratios ((DELTA)p/p(,0))/((DELTA)T/T(,0)) are nearly represented by the Hansen-Morse model for simple gases, argon, air and carbon dioxide. The sulfur dioxide data are not quantitatively given by the theory due to inadequacy of the Hansen-Morse model for strongly polar gases. The work was also extended to a cylindrical annulus where comparisons were made with the Poiseuille flow data for helium, air, hydrogen and carbon dioxide. The cross effects were also studied for arbitrary (alpha), the fraction of molecules that are diffusely reflected from the surface, for a gas confined between parallel plates and in a cylindrical tube. The comparisons of the experimental thermal transpiration data with the theoretical results yielded (alpha) values which lie between 0.8 and 1.0, as expected for the "engineering surfaces.".

  9. Some analytical results for thermal transpiration and the mechanocaloric effect in a cylindrical tube

    Science.gov (United States)

    Lang, H.; Loyalka, S. K.

    1984-07-01

    Analytical expressions for the phenomenological coefficients for thermal transpiration and the mechanocaloric effect in a cylindrical tube, relating to flow of a rarefied gas, are obtained by considering the BGK model. Neumann iteration and variational techniques are used in the near free molecular regime and the method of elementary solutions is used in the near continuum regime. The previously reported results of Ferziger and Loyalka on Poiseuille and thermal creep flows are extended and augmented.

  10. Comparison of root water uptake modules using either the surface energy balance or potential transpiration

    OpenAIRE

    I. Braud; Varado, N.; A. Olioso

    2005-01-01

    Numerical models simulating changes in soil water content with time rely on accurate estimation of root water uptake. This paper considers two root water uptake modules that have a compensation mechanism allowing for increased root uptake under conditions of water stress. These modules, proposed by Lai and Katul and Li et al. [Adv. Water Resour. 2.3 (2000) 427 and J. Hydrol. 252 (2001) 189] use potential transpiration weighted, for each soil layer, by a water stress and a compensation functio...

  11. Groundwater and unsaturated zone evaporation and transpiration in a semi-arid open woodland

    Science.gov (United States)

    Balugani, E.; Lubczynski, M. W.; Reyes-Acosta, L.; van der Tol, C.; Francés, A. P.; Metselaar, K.

    2017-04-01

    Studies on evapotranspiration partitioning under eddy covariance (EC) towers rarely address the separate effects of transpiration and evaporation on groundwater resources. Such partitioning is important to accurately assess groundwater resources, especially in arid and semi-arid areas. The main objective of this study was to partition (evaluate separately) the evaporation and transpiration components of evapotranspiration, originated either from saturated or unsaturated zone, and estimate their contributions in a semi-arid area characterized by relatively shallow groundwater Table (0-10 m deep). Evapotranspiration, tree transpiration and subsurface evaporation were estimated with EC tower, using sap flow methods and HYDRUS1D model, respectively. To set up the HYDRUS1D model, soil material properties, soil moisture, soil temperature, soil matric potential and water table depth were measured in the area. The tree transpiration was sourced into groundwater and unsaturated zone components (∼0.017 mm d-1 for both) and accounted for only ∼6% of the evapotranspiration measured by the EC tower (∼0.565 mm d-1), due to the low canopy coverage in the study area (7%). The subsurface evaporation fluxes were also sourced into groundwater and unsaturated zone components using the SOURCE package, and their relative relevance in total evapotranspiration was assessed. Subsurface evaporation was the main flux year-round (∼0.526 mm d-1). During late autumn, winter and early spring time, the unsaturated zone evaporation was dominant, while in dry summer the relevance of groundwater evaporation increased, reaching one third of evapotranspiration, although errors in the water balance closure point still at its possible underestimation. The results show that, in arid and semi-arid areas with sparse vegetation, the often neglected groundwater evaporation is a relevant contribution to evapotranspiration, and that water vapor flow should be taken into account in the calculation of

  12. Regulation of transpirational water loss in Quercus suber trees in a Mediterranean-type ecosystem.

    Science.gov (United States)

    Otieno, D O; Schmidt, M W T; Kurz-Besson, C; Lobo Do Vale, R; Pereira, J S; Tenhunen, J D

    2007-08-01

    Sap flux density in branches, leaf transpiration, stomatal conductance and leaf water potentials were measured in 16-year-old Quercus suber L. trees growing in a plantation in southern Portugal to understand how evergreen Mediterranean trees regulate water loss during summer drought. Leaf specific hydraulic conductance and leaf gas exchange were monitored during the progressive summer drought to establish how changes along the hydraulic pathway influence shoot responses. As soil water became limiting, leaf water potential, stomatal conductance and leaf transpiration declined significantly. Predawn leaf water potential reflected soil water potential measured at 1-m depth in the rhizospheres of most trees. The lowest predawn leaf water potential recorded during this period was -1.8 MPa. Mean maximum stomatal conductance declined from 300 to 50 mmol m(-2) s(-1), reducing transpiration from 6 to 2 mmol m(-2) s(-1). Changes in leaf gas exchange were attributed to reduced soil water availability, increased resistances along the hydraulic pathway and, hence, reduced leaf water supply. There was a strong coupling between changes in soil water content and stomatal conductance as well as between stomatal conductance and leaf specific hydraulic conductance. Despite significant seasonal differences among trees in predawn leaf water potential, stomatal conductance, leaf transpiration and leaf specific hydraulic conductance, there were no differences in midday leaf water potentials. The strong regulation of changes in leaf water potential in Q. suber both diurnally and seasonally is achieved through stomatal closure, which is sensitive to changes in both liquid and vapor phase conductance. This sensitivity allows for optimization of carbon and water resource use without compromising the root-shoot hydraulic link.

  13. An Experimental Investigation on Transpiration Cooling Part II: Comparison of Cooling Methods and Media

    OpenAIRE

    Wang J; Messner J.; Stetter H.

    2004-01-01

    This article attempts to provide a cooling performance comparison of various mass transfer cooling methods and different cooling media through two experiments. In the first experiment, pressurized air was used as a cooling medium and two different circular tubes were used as specimens. One is made of impermeable solid material with four rows of discrete holes to simulate film cooling, and the other consists of sintered porous material to create a porous transpiration cooling effect. The...

  14. A hybrid dual-source model for potential evaporation and transpiration partitioning

    Science.gov (United States)

    Guan, Huade; Wilson, John L.

    2009-10-01

    SummaryPotential ET (PET) and partitioning of evaporation and transpiration are important information for hydrologic, ecologic, forest, and agricultural studies. Most PET models were developed in flat areas for agricultural purposes, with potential evaporation (PE) and potential transpiration (PT) lumped together. To quantify the evaporative demand for sloped surfaces with a wide range of vegetation coverage, a topography- and vegetation-based surface energy partitioning algorithm for PE and PT estimates (TVET) is developed. In this paper, vegetation-based part of the TVET model is presented. TVET employs a hybrid of layer and patch approaches in partitioning energy and routing vapor and sensible heat. It first uses a layer approach to partition available energy for the canopy and the soil components. The available energy of each component is then partitioned into potential latent heat and sensible heat, using a patch approach. Hybrid of these two approaches results in simple model formulae, while coupling the two components in terms of energy partitioning and aerodynamic resistances for heat and vapor transfer. TVET is different from a layer-approach model in that it distinguishes the difference in evaporation from inter-canopy soil and from under-canopy soil, and limits convective transfer contribution to transpiration only for vegetation-cover fraction. TVET is different from a patch-approach model in that it allows evaporation occurring from under-canopy soil, and that vegetation effect on both evaporation and transpiration is well considered. These features make TVET sensitive to vegetation effect on surface energy partitioning. The model is demonstrated and tested with Penman-Monteith and Shuttleworth-Wallace models, and with observations, at four sites covering mountain, basin floor, and riparian environments. The results indicate that TVET can be used to estimate PE and PT partitioning for a wide range of surfaces with different fractional vegetation cover

  15. An extension of the transpired skin-friction equation to compressible turbulent boundary layers

    Science.gov (United States)

    Silva-Freire, Atila P.

    1988-11-01

    A skin-friction equation for transpired incompressible turbulent boundary layer, proposed in a previous paper (Silva-Freire, 1988), is extended to compressible flow. The expression derived here is simple and gives more consistent results than the momentum-integral equation. The difficulty with the present formulation, however, is that the wake profile parameter due to injection has to be carefully determined in order to obtain good results.

  16. Accumulation and distribution of arsenic and cadmium by tea plants

    Institute of Scientific and Technical Information of China (English)

    Yuan-zhi SHI; Jian-yun RUAN; Lifeng MA; Wen-yan HAN; Fang WANG

    2008-01-01

    It is important to research the rules about accumulation and distribution of arsenic and cadmium by tea plants, which will give us some scientific ideas about how to control the contents of arsenic and cadmium in tea. In this study, by field inves- tigation and pot trial, we found that mobility of arsenic and cadmium in tea plants was low. Most arsenic and cadmium absorbed were fixed in feeding roots and only small amount was transported to the above-ground parts. Distribution of arsenic and cadmium, based on their concentrations of unit dry matter, in tea plants grown on un-contaminated soil was in the order: feeding roots>stems≈main roots>old leaves>young leaves. When tea plants were grown on polluted soils simulated by adding salts of these two metals, feeding roots possibly acted as a buffer and defense, and arsenic and cadmium were transported less to the above- ground parts. The concentration of cadmium in soil significantly and negatively correlated with chlorophyll content, photosyn- thetic rate, transpiration rate and biomass production of tea plants.

  17. Energy Balance, Evapo-transpiration and Dew deposition in the Dead Sea Valley

    Science.gov (United States)

    Metzger, Jutta; Corsmeier, Ulrich

    2016-04-01

    The Dead Sea is a unique place on earth. It is a terminal hypersaline lake, located at the lowest point on earth with a lake level of currently -429 m above mean sea level (amsl). It is located in a transition zone of semiarid to arid climate conditions, which makes it highly sensible to climate change (Alpert1997, Smiatek2011). The Virtual Institute DEad SEa Research Venue (DESERVE) is an international project funded by the German Helmholtz Association and was established to study coupled atmospheric hydrological, and lithospheric processes in the changing environment of the Dead Sea. At the moment the most prominent environmental change is the lake level decline of approximately 1 m / year due to anthropogenic interferences (Gertman, 2002). This leads to noticeable changes in the fractions of the existing terrestrial surfaces - water, bare soil and vegetated areas - in the valley. Thus, the partitioning of the net radiation in the valley changes as well. To thoroughly study the atmospheric and hydrological processes in the Dead Sea valley, which are driven by the energy balance components, sound data of the energy fluxes of the different surfaces are necessary. Before DESERVE no long-term monitoring network simultaneously measuring the energy balance components of the different surfaces in the Dead Sea valley was available. Therefore, three energy balance stations were installed at three characteristic sites at the coast-line, over bare soil, and within vegetation, measuring all energy balance components by using the eddy covariance method. The results show, that the partitioning of the energy into sensible and latent heat flux on a diurnal scale is totally different at the three sites. This results in gradients between the sites, which are e.g. responsible for the typical diurnal wind systems at the Dead Sea. Furthermore, driving forces of evapo-transpiration at the sites were identified and a detailed analysis of the daily evaporation and dew deposition rates

  18. Transpirative Deficit Index (TDI) for the management of water scarcity in irrigated areas: development and application in northern Italy

    Science.gov (United States)

    Borghi, Anna; Facchi, Arianna; Rienzner, Michele; Gandolfi, Claudio

    2016-04-01

    In Europe, the monitoring and assessment of drought is entrusted to the European Drought Observatory (EDO). EDO indicators are calculated considering rainfed agriculture and delivered on a 5 km grid. However, in southern Europe, irrigation may compensate for potentially severe agricultural droughts and specific water scarcity indicators that explicitly consider irrigation are needed. In the Po River Plain, irrigated crops cover more than 70% of the agricultural land, massive amounts of water are diverted from rivers for irrigation, and surface irrigation methods are largely applied. Nowadays, the region is not a water scarce basin, but irrigation water shortages have occurred with increased frequency during the last two decades. Moreover, a recent EU report shows that the Po River Plain is included among areas in Europe that by 2030 shall be affected by water scarcity. In this context, a study was started to select and develop indicators for the management and prevention of Water Scarcity and Drought (WS&D) based on the synergic use of hydrological modelling and Earth Observation data applied at a spatial scale of interest for end-users (250m grid). These indicators shall be better suited for the assessment of WS&D in Italy as well as in other southern European countries. This work presents the development and the application of the TDI (Transpirative Deficit Index) to a study area, within the Po River Plain. TDI is an agricultural drought index based on the transpiration deficit (TDx, calculated as the difference between potential and actual transpiration), computed by the spatially distributed hydrological model IDRAGRA and cumulated over a period of x days. TDx for each day of a specific year is compared to the long-term TDx probability distribution (e.g., over 20-30 years), which is transformed into a standardized normal distribution. The non-exceedance probability of TDx is finally expressed in terms of unit of standard deviation (TDI), following the approach

  19. Soil organic matter influences cerium translocation and physiological processes in kidney bean plants exposed to cerium oxide nanoparticles.

    Science.gov (United States)

    Majumdar, Sanghamitra; Peralta-Videa, Jose R; Trujillo-Reyes, Jesica; Sun, Youping; Barrios, Ana C; Niu, Genhua; Margez, Juan P Flores-; Gardea-Torresdey, Jorge L

    2016-11-01

    Soil organic matter plays a major role in determining the fate of the engineered nanomaterials (ENMs) in the soil matrix and effects on the residing plants. In this study, kidney bean plants were grown in soils varying in organic matter content and amended with 0-500mg/kg cerium oxide nanoparticles (nano-CeO2) under greenhouse condition. After 52days of exposure, cerium accumulation in tissues, plant growth and physiological parameters including photosynthetic pigments (chlorophylls and carotenoids), net photosynthesis rate, transpiration rate, and stomatal conductance were recorded. Additionally, catalase and ascorbate peroxidase activities were measured to evaluate oxidative stress in the tissues. The translocation factor of cerium in the nano-CeO2 exposed plants grown in organic matter enriched soil (OMES) was twice as the plants grown in low organic matter soil (LOMS). Although the leaf cover area increased by 65-111% with increasing nano-CeO2 concentration in LOMS, the effect on the physiological processes were inconsequential. In OMES leaves, exposure to 62.5-250mg/kg nano-CeO2 led to an enhancement in the transpiration rate and stomatal conductance, but to a simultaneous decrease in carotenoid contents by 25-28%. Chlorophyll a in the OMES leaves also decreased by 27 and 18% on exposure to 125 and 250mg/kg nano-CeO2. In addition, catalase activity increased in LOMS stems, and ascorbate peroxidase increased in OMES leaves of nano-CeO2 exposed plants, with respect to control. Thus, this study provides clear evidence that the properties of the complex soil matrix play decisive roles in determining the fate, bioavailability, and biological transport of ENMs in the environment. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. Wetland tree transpiration modified by river-floodplain connectivity

    Science.gov (United States)

    Allen, Scott T; Krauss, Ken W.; Cochran, J. Wesley; King, Sammy L.; Keim, Richard F.

    2016-01-01

    Hydrologic connectivity provisions water and nutrient subsidies to floodplain wetlands and may be particularly important in floodplains with seasonal water deficits through its effects on soil moisture. In this study, we measured sapflow in 26 trees of two dominant floodplain forest species (Celtis laevigata and Quercus lyrata) at two hydrologically distinct sites in the lower White River floodplain in Arkansas, USA. Our objective was to investigate how connectivity-driven water table variations affected water use, an indicator of tree function. Meteorological variables (photosynthetically active radiation and vapor pressure deficit) were the dominant controls over water use at both sites; however, water table variations explained some site differences. At the wetter site, highest sapflow rates were during a late-season overbank flooding event, and no flood stress was apparent. At the drier site, sapflow decreased as the water table receded. The late-season flood pulse that resulted in flooding at the wetter site did not affect the water table at the drier site; accordingly, higher water use was not observed at the drier site. The species generally associated with wetter conditions (Q. lyrata) was more positively responsive to the flood pulse. Flood water subsidy lengthened the effective growing season, demonstrating ecological implications of hydrologic connectivity for alleviating water deficits that otherwise reduce function in this humid floodplain wetland.

  1. Rate Constants of PSII Photoinhibition and its Repair, and PSII Fluorescence Parameters in Field Plants in Relation to their Growth Light Environments.

    Science.gov (United States)

    Miyata, Kazunori; Ikeda, Hiroshi; Nakaji, Masayoshi; Kanel, Dhana Raj; Terashima, Ichiro

    2015-09-01

    The extent of photoinhibition of PSII is determined by a balance between the rate of photodamage to PSII and that of repair of the damaged PSII. It has already been indicated that the rate constants of photodamage (kpi) and repair (krec) of the leaves differ depending on their growth light environment. However, there are no studies using plants in the field. We examined these rate constants and fluorescence parameters of several field-grown plants to determine inter-relationships between these values and the growth environment. The kpi values were strongly related to the excess energy, EY, of the puddle model and non-regulated energy dissipation, Y(NO), of the lake model, both multiplied by the photosynthetically active photon flux density (PPFD) level during the photoinhibitory treatment. In contrast, the krec values corrected against in situ air temperature were very strongly related to the daily PPFD level. The plants from the fields showed higher NPQ than the chamber-grown plants, probably because these field plants acclimated to stronger lightflecks than the averaged growth PPFD. Comparing chamber-grown plants and the field plants, we showed that kpi is determined by the incident light level and the photosynthetic capacities such as in situ rate of PSII electron transport and non-photochemical quenching (NPQ) [e.g. Y(NO)×PPFD] and that krec is mostly determined by the growth light and temperature levels. © The Author 2015. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  2. Model-assisted analysis of spatial and temporal variations in fruit temperature and transpiration highlighting the role of fruit development.

    Directory of Open Access Journals (Sweden)

    Thibault Nordey

    Full Text Available Fruit physiology is strongly affected by both fruit temperature and water losses through transpiration. Fruit temperature and its transpiration vary with environmental factors and fruit characteristics. In line with previous studies, measurements of physical and thermal fruit properties were found to significantly vary between fruit tissues and maturity stages. To study the impact of these variations on fruit temperature and transpiration, a modelling approach was used. A physical model was developed to predict the spatial and temporal variations of fruit temperature and transpiration according to the spatial and temporal variations of environmental factors and thermal and physical fruit properties. Model predictions compared well to temperature measurements on mango fruits, making it possible to accurately simulate the daily temperature variations of the sunny and shaded sides of fruits. Model simulations indicated that fruit development induced an increase in both the temperature gradient within the fruit and fruit water losses, mainly due to fruit expansion. However, the evolution of fruit characteristics has only a very slight impact on the average temperature and the transpiration per surface unit. The importance of temperature and transpiration gradients highlighted in this study made it necessary to take spatial and temporal variations of environmental factors and fruit characteristics into account to model fruit physiology.

  3. Seasonal shift in climatic limiting factors on tree transpiration: evidence from sap flow observations at alpine treelines in southeast Tibet

    Directory of Open Access Journals (Sweden)

    Liu Xinsheng

    2016-07-01

    Full Text Available Alpine and northern treelines are primarily controlled by low temperatures. However, little is known about the impact of low soil temperature on tree transpiration at treelines. We aim to test the hypothesis that in cold-limited forests, the main limiting factors for tree transpiration switch from low soil temperature before summer solstice to atmospheric evaporative demand after summer solstice, which generally results in low transpiration in the early growing season. Sap flow, meteorological factors and predawn needle water potential were continuously monitored throughout one growing season across Smith fir (Abies georgei var. smithii and juniper (Juniperus saltuaria treelines in southeast Tibet. Sap flow started in early May and corresponded to a threshold mean air-temperature of 0 oC. Across tree species, transpiration was mainly limited by low soil temperature prior to the summer solstice but by vapor pressure deficit and solar radiation post-summer solstice, which was further confirmed on a daily scale. As a result, tree transpiration for both tree species was significantly reduced in the pre-summer solstice period as compared to post-summer solstice, resulting in a lower predawn needle water potential for Smith fir trees in the early growing season. Our data supported the hypothesis, suggesting that tree transpiration mainly responds to soil temperature variations in the early growing season. The results are important for understanding the hydrological response of cold-limited forest ecosystems to climate change.

  4. Seasonal Shift in Climatic Limiting Factors on Tree Transpiration: Evidence from Sap Flow Observations at Alpine Treelines in Southeast Tibet.

    Science.gov (United States)

    Liu, Xinsheng; Nie, Yuqin; Luo, Tianxiang; Yu, Jiehui; Shen, Wei; Zhang, Lin

    2016-01-01

    Alpine and northern treelines are primarily controlled by low temperatures. However, little is known about the impact of low soil temperature on tree transpiration at treelines. We aim to test the hypothesis that in cold-limited forests, the main limiting factors for tree transpiration switch from low soil temperature before summer solstice to atmospheric evaporative demand after summer solstice, which generally results in low transpiration in the early growing season. Sap flow, meteorological factors and predawn needle water potential were continuously monitored throughout one growing season across Smith fir (Abies georgei var. smithii) and juniper (Juniperus saltuaria) treelines in southeast Tibet. Sap flow started in early May and corresponded to a threshold mean air-temperature of 0°C. Across tree species, transpiration was mainly limited by low soil temperature prior to the summer solstice but by vapor pressure deficit and solar radiation post-summer solstice, which was further confirmed on a daily scale. As a result, tree transpiration for both tree species was significantly reduced in the pre-summer solstice period as compared to post-summer solstice, resulting in a lower predawn needle water potential for Smith fir trees in the early growing season. Our data supported the hypothesis, suggesting that tree transpiration mainly responds to soil temperature variations in the early growing season. The results are important for understanding the hydrological response of cold-limited forest ecosystems to climate change.

  5. Effects of Different Fertilizer Rates, Planting Density and Plant Growth Regulators on Yield of Soybean Cultivar Tiedou 68%肥密化控对铁豆68号产量的影响

    Institute of Scientific and Technical Information of China (English)

    董友魁; 刘德恒; 韩艳红

    2015-01-01

    采用正交试验对影响铁豆68号产量的密度、施肥量、叶面喷肥、化控次数4因素进行研究,结果表明,对大豆新品种铁豆68号产量影响的顺序是:施肥量、密度、叶面喷肥、化控次数;铁豆68号最理想的栽培技术模式是密度1.1万株/667m2,施肥量为20 kg/667m2,叶面喷肥1次,化控次数1次。%In order to examine the effects of planting density, fertilization rates, foliar application and times of plant growth regulator application during the growing period of soybean cultivar Tiedou 68, the orthogonal experimental design was used to carry out data analysis. The result indicated that the order of cultivation practices on soybean new variety Tiedou 68 was: fertilization rate, planting density, foliar application and times of plant growth regulator application. The ideal cultural pattern of cultivar Tiedou 68 was planting density of 11 000/667m2, fertilization rate of 20 kg/667m2, and one time of foliar and plant growth regulator application.

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

    Science.gov (United States)

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

    2012-08-01

    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.

  7. Flexible resource allocation during plant defense responses

    Directory of Open Access Journals (Sweden)

    Jack C. Schultz

    2013-08-01

    Full Text Available Plants are organisms composed of modules connected by xylem and phloem transport streams. Attack by both insects and pathogens elicits sometimes rapid defense responses in the attacked module. We have also known for some time that proteins are often reallocated away from pathogen-infected tissues, while the same infection sites may draw carbohydrates to them. This has been interpreted as a tug of war in which the plant withdraws critical resources to block microbial growth while the microbes attempt to acquire more resources. Sink-source regulated transport among modules of critical resources, particularly carbon and nitrogen, is also altered in response to attack. Insects and jasmonate can increase local sink strength, drawing carbohydrates that support defense production. Shortly after attack, carbohydrates may also be drawn to the root. The rate and direction of movement of photosynthate or signals in phloem in response to attack is subject to constraints that include branching, degree of connection among tissues, distance between sources and sinks, proximity, strength, and number of competing sinks, and phloem loading/unloading regulators. Movement of materials (e.g., amino acids, signals to or from attack sites in xylem is less well understood but is partly driven by transpiration. The root is an influential sink and may regulate sink-source interactions and transport above and below ground as well as between the plant and the rhizosphere and nearby, connected plants. Research on resource translocation in response to pathogens or herbivores has focused on biochemical mechanisms; whole-plant research is needed to determine which, if any, of these plant behaviors actually influence plant fitness.

  8. The effects of Brassica green manures on plant parasitic and free living nematodes used in combination with reduced rates of synthetic nematicides.

    Science.gov (United States)

    Riga, Ekaterini

    2011-06-01

    Brassica plants once incorporated into soil as green manures have recently been shown to have biofumigant properties and have the potential of controlling plant-parasitic nematodes. In Washington State, plant-parasitic nematodes are successfully managed with synthetic nematicides. However, some of the synthetic nematicides became unavailable recently or their supply is limited leaving growers with few choices to control plant-parasitic nematodes. The objective of this project was to evaluate the effects of Brassica green manures on their own and in combination with reduced rates of synthetic nematicides on plant-parasitic nematodes and free living nematodes. In a greenhouse experiment and field trials in three seasons, Brassica green manures in combination with half the recommended rate of 1,3-dichloropropene (1,3-D, Telone) reduced root knot nematode, Meloidogyne chitwoodi to below detection levels, and reduced lesion nematodes, Pratylenchus penetrans and stubby root nematodes, Paratrichodorus allius, to below economic thresholds. The combination treatments did not affect the beneficial free-living nematode populations and the non-pathogenic Pseudomonas. The total cost of growing and soil-incorporating Brassica crops as green manures in combination with reduced rates of 1,3-D was approximately 35% lower than the present commercial costs for application for the full rate of this fumigant. Integrating conventional management practices with novel techniques fosters sustainability of production systems and can increase economic benefit to producers while reducing chemical input.

  9. Measurement and Empirical Correlation of Transpiration-Cooling Parameters on a 25 degree Cone in a Turbulent Boundary Layer in Both Free Flight and a Hot-Gas Jet

    Science.gov (United States)

    Walton, Thomas E., Jr.; Rashis, Bernard

    1961-01-01

    Transpiration-cooling parameters are presented for a turbulent boundary layer on a cone configuration with a total angle of 250 which was tested in both free flight and in an ethylene-heated high-temperature jet at a Mach number of 2.0. The flight-tested cone was flown to a maximum Mach number of 4.08 and the jet tests were conducted at stagnation temperatures ranging from 937 R to 1,850 R. In general, the experimental heat transfer was in good agreement with the theoretical values. Inclusion of the ratio of local stream temperature to wall temperature in the nondimensional flow rate parameter enabled good correlation of both sets of transpiration data. The measured pressure at the forward station coincided with the theoretical pressure over a sharp cone; however, the measured pressure increased with distance from the nose tip.

  10. [Photosynthetic characteristics of an invasive plant Conyza canadensis and its associated plants].

    Science.gov (United States)

    Wang, Xiao-Hong; Ji, Ming-Shan

    2013-01-01

    To explore the invasion mechanisms of Conyza canadensis and develop effective control measures, this paper studied the photosynthetic characteristics of the invasive plant and its main associated plants Ixeris chinensis and Commelina communis. The light saturation point and light compensation point of C. canadensis were 1634.00 and 23.84 micromol x m(-2) x s(-1), respectively, which were between those of the two associated plants. The maximum net photosynthetic rate of C. canadensis below light saturation point was 28.12 micromol x m(-2) x s(-1), being much higher than that of the two associated plants. The apparent quantum yield of C. canadensis was 0.06, equal to that of I. chinensis but higher than that of C. communis. The CO2 saturation point and CO2 compensation point of C. canadensis were 834.00 and 23.69 micromol x mol(-1), respectively. The maximum net photosynthetic rate of C. canadensis below CO2 saturation point was 31.97 micromol x m(-2) x s(-1), which was between that of the two associated species. The carboxylation efficiency of C. canadensis was 0.078, being higher than that of the two associated species. The variations of photosynthetically active radiation and CO2 concentration had little effects on the stomatal conductance and transpiration rate of the three plants, but significantly affected their water use efficiency. C. canadensis had higher photosynthetic rate and material accumulation capability, and its high productivity could be one of the important factors for its successful invasion.

  11. Leaf d15N as a physiological indicator of the responsiveness of N2-fixing alfalfa plants to elevated [CO2], temperature and low water availability

    Directory of Open Access Journals (Sweden)

    Idoia eAriz

    2015-08-01

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

  12. Determination of the Optimized Automation Rate considering Effects of Automation on Human Operators in Nuclear Power Plants

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Seung Min; Seong, Poong Hyun [Korea Advanced Institute of Science and Technology, Daejon (Korea, Republic of); Kim, Jong Hyun [KEPCO International Nuclear Graduate School, Seosaeng (Korea, Republic of); Kim, Man Cheol [Chung-Ang University, Seoul (Korea, Republic of)

    2015-05-15

    Automation refers to the use of a device or a system to perform a function previously performed by a human operator. It is introduced to reduce the human errors and to enhance the performance in various industrial fields, including the nuclear industry. However, these positive effects are not always achieved in complex systems such as nuclear power plants (NPPs). An excessive introduction of automation can generate new roles for human operators and change activities in unexpected ways. As more automation systems are accepted, the ability of human operators to detect automation failures and resume manual control is diminished. This disadvantage of automation is called the Out-of-the- Loop (OOTL) problem. We should consider the positive and negative effects of automation at the same time to determine the appropriate level of the introduction of automation. Thus, in this paper, we suggest an estimation method to consider the positive and negative effects of automation at the same time to determine the appropriate introduction of automation. This concept is limited in that it does not consider the effects of automation on human operators. Thus, a new estimation method for automation rate was suggested to overcome this problem.

  13. Hydrological, chemical, and isotopic budgets of Lake Chad: a quantitative assessment of evaporation, transpiration and infiltration fluxes

    Science.gov (United States)

    Bouchez, Camille; Goncalves, Julio; Deschamps, Pierre; Vallet-Coulomb, Christine; Hamelin, Bruno; Doumnang, Jean-Claude; Sylvestre, Florence

    2016-04-01

    In the Sahelian belt, Lake Chad is a key water body for 13 million people, who live on its resources. It experiences, however, substantial and frequent surface changes. Located at the centre of one of the largest endorheic basins in the world, its waters remain surprisingly fresh. Its low salinity has been attributed to a low infiltration flow whose value remains poorly constrained. Understanding the lake's hydrological behaviour in response to climate variability requires a better constraint of the factors that control its water and chemical balance. Based on the three-pool conceptualization of Lake Chad proposed by Bader et al. (2011), this study aims to quantify the total water outflow from the lake, the respective proportions of evaporation (E), transpiration (T), and infiltration (I), and the associated uncertainties. A Bayesian inversion method based on lake-level data was used, leading to total water loss estimates in each pool (E + T + I = ETI). Sodium and stable isotope mass balances were then used to separate total water losses into E, T, and I components. Despite the scarcity of representative data available on the lake, the combination of these two geochemical tracers is relevant to assess the relative contribution of these three outflows involved in the control of the hydrological budget. Mean evapotranspiration rates were estimated at 2070 ± 100 and 2270 ± 100 mm yr-1 for the southern and northern pools, respectively. Infiltration represents between 100 and 300 mm yr-1 but most of the water is evapotranspirated in the first few kilometres from the shorelines and does not efficiently recharge the Quaternary aquifer. Transpiration is shown to be significant, around 300 mm yr-1 and reaches 500 mm yr-1 in the vegetated zone of the archipelagos. Hydrological and chemical simulations reproduce the marked hydrological change between the normal lake state that occurred before 1972 and the small lake state after 1972 when the lake surface shrunk to a one

  14. Canopy-scale biophysical controls of transpiration and evaporation in the Amazon Basin

    Science.gov (United States)

    Mallick, Kaniska; Trebs, Ivonne; Boegh, Eva; Giustarini, Laura; Schlerf, Martin; Drewry, Darren T.; Hoffmann, Lucien; von Randow, Celso; Kruijt, Bart; Araùjo, Alessandro; Saleska, Scott; Ehleringer, James R.; Domingues, Tomas F.; Ometto, Jean Pierre H. B.; Nobre, Antonio D.; Leal de Moraes, Osvaldo Luiz; Hayek, Matthew; Munger, J. William; Wofsy, Steven C.

    2016-10-01

    Canopy and aerodynamic conductances (gC and gA) are two of the key land surface biophysical variables that control the land surface response of land surface schemes in climate models. Their representation is crucial for predicting transpiration (λET) and evaporation (λEE) flux components of the terrestrial latent heat flux (λE), which has important implications for global climate change and water resource management. By physical integration of radiometric surface temperature (TR) into an integrated framework of the Penman-Monteith and Shuttleworth-Wallace models, we present a novel approach to directly quantify the canopy-scale biophysical controls on λET and λEE over multiple plant functional types (PFTs) in the Amazon Basin. Combining data from six LBA (Large-scale Biosphere-Atmosphere Experiment in Amazonia) eddy covariance tower sites and a TR-driven physically based modeling approach, we identified the canopy-scale feedback-response mechanism between gC, λET, and atmospheric vapor pressure deficit (DA), without using any leaf-scale empirical parameterizations for the modeling. The TR-based model shows minor biophysical control on λET during the wet (rainy) seasons where λET becomes predominantly radiation driven and net radiation (RN) determines 75 to 80 % of the variances of λET. However, biophysical control on λET is dramatically increased during the dry seasons, and particularly the 2005 drought year, explaining 50 to 65 % of the variances of λET, and indicates λET to be substantially soil moisture driven during the rainfall deficit phase. Despite substantial differences in gA between forests and pastures, very similar canopy-atmosphere "coupling" was found in these two biomes due to soil moisture-induced decrease in gC in the pasture. This revealed the pragmatic aspect of the TR-driven model behavior that exhibits a high sensitivity of gC to per unit change in wetness as opposed to gA that is marginally sensitive to surface wetness variability

  15. Radiocesium contaminations of 20 wood species and the corresponding gamma-ray dose rates around the canopies at 5 months after the Fukushima nuclear power plant accident.

    Science.gov (United States)

    Yoshihara, Toshihiro; Matsumura, Hideyuki; Hashida, Shin-nosuke; Nagaoka, Toru

    2013-01-01

    Radiocesium ((134)Cs + (137)Cs) deposition from the Fukushima nuclear power plant accident was measured in 20 woody plants (12 evergreen and 8 deciduous species) grown in Abiko (approximately 200 km SSW from the NPP). Leaves (needles) and twigs were sampled from each of three foliar positions (top, middle, and bottom) in the plant canopy in early August 2011. At the time, soils around the plants were also sampled, and gamma radiation dose rates were measured at each sampling position. The average radiocesium activity in the observed leaves of the evergreen species was 7.7 times that in the leaves of the deciduous species. Among the observed evergreen coniferous species, the activity in pre-fallout-expanded leaves was 2.4 times that in the post-fallout-expanded leaves. Notably, a distinct variation in the activity among the evergreen coniferous species could be observed for the post-fallout-expanded leaves but not for the pre-fallout-expanded leaves. Although these differences depend on whether the leaves had expanded at the time of the fallout, it is probable that a considerable amount of radiocesium was translocated to newly developed leaves at a species-specific rate. In addition, it was demonstrated that dose rates around woody plants were not consistent with the prevailing prediction that general dose rates correspondingly decrease with monitoring height from the ground. Thus, the dose rates in the top foliar layer of the deciduous species decreased more than predicted, whereas those in the top foliar layer of the coniferous species did not decrease. This may be due to differences in the balance between the attenuation resulting from a shielding effect of the plant bodies and the higher radiocesium accumulation in the leaves.

  16. Effect of soil moisture, over field capacity, on growth of beans plants (phaseolus vulgaris L.); Efecto de la humedad del suelo, por encima de la capacidad de campo sobre el crecimiento de plantas de judia (phaseolus vulgaris L.) Durante un mes de desarrollo

    Energy Technology Data Exchange (ETDEWEB)

    Ballesteros, M.; Mazon, M. P.

    1985-07-01

    The effect of soil moisture, over field capacity, on growth and photosynthesis of three moisture levels (20,30 and 40 %) was studied.The first moisture level was near field capacity while the others exceeded. Weekly dry weight of different plant parts, chlorophyll content, net CO{sub 2} exchange rate in light and darkness, 14{sup C}O{sub 2} assimilated rate and stomatal aperture were determined. Results show a positive effect of soil moisture over field capacity on growth, photosynthate and transpiration of beans during the first growing month. (Author) 76 refs.

  17. Single Plant Root System Modeling under Soil Moisture Variation

    Science.gov (United States)

    Yabusaki, S.; Fang, Y.; Chen, X.; Scheibe, T. D.

    2016-12-01

    A prognostic Virtual Plant-Atmosphere-Soil System (vPASS) model is being developed that integrates comprehensively detailed mechanistic single plant modeling with microbial, atmospheric, and soil system processes in its immediate environment. Three broad areas of process module development are targeted: Incorporating models for root growth and function, rhizosphere interactions with bacteria and other organisms, litter decomposition and soil respiration into established porous media flow and reactive transport models Incorporating root/shoot transport, growth, photosynthesis and carbon allocation process models into an integrated plant physiology model Incorporating transpiration, Volatile Organic Compounds (VOC) emission, particulate deposition and local atmospheric processes into a coupled plant/atmosphere model. The integrated plant ecosystem simulation capability is being developed as open source process modules and associated interfaces under a modeling framework. The initial focus addresses the coupling of root growth, vascular transport system, and soil under drought scenarios. Two types of root water uptake modeling approaches are tested: continuous root distribution and constitutive root system architecture. The continuous root distribution models are based on spatially averaged root development process parameters, which are relatively straightforward to accommodate in the continuum soil flow and reactive transport module. Conversely, the constitutive root system architecture models use root growth rates, root growth direction, and root branching to evolve explicit root geometries. The branching topologies require more complex data structures and additional input parameters. Preliminary results are presented for root model development and the vascular response to temporal and spatial variations in soil conditions.

  18. Analysis of power ramp rate and minimum power controllability of the MMS model for a plant dynamics analysis of a Prototype SFR

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Eui Kwang; Kim, Dehee; Joo, Hyungkook; Lee, Taeho [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2014-05-15

    A full plant dynamic model was developed for a prototype SFR using the Modular Modeling System (MMS). It includes the modeling of various subsystems such as the neutronics, primary and intermediate sodium systems of the NSSS, steam and water systems of the BOP, BOP controls, and the supervisory plant controls. The NSSS model is subdivided into component models, such as a Core, IHXs, Pumps, SGs, and the rest of the NSSS loop model. The BOP model is subdivided into a steam subsystem, feedwater subsystem, and preheater subsystem. Plant transient tests were performed to study the operational considerations. It includes varying the power ramp rate and studying the controllability at minimum power. Plant transient tests were performed to study operational considerations by using the MMS model for a prototype SFR. It includes varying the power ramp rate, studying the controllability at the minimum power set point. At a power ramp rate of higher than 2%, the steam temperature has a large deviation from the target. As the power set point decreases, the PHTS hot leg temperature and steam temperature tend to have higher deviations. After further refinement of the MMS model, it can be useful for developing the plant operation logics of the prototype SFR.

  19. Transpiration of montane Pinus sylvestris L. and Quercus pubescens Willd. forest stands measured with sap flow sensors in NE Spain

    Directory of Open Access Journals (Sweden)

    R. Poyatos

    2005-01-01

    Full Text Available Stand transpiration was measured during the 2003 and 2004 growing seasons using heat dissipation sap flow sensors in a Scots pine (Pinus sylvestris L. and a pubescent oak (Quercus pubescens Willd. forests located in a montane area of the Eastern Pyrenees (NE Spain. The first aim of the study was to assess the differences in quantitative estimates of transpiration (Ec and the response to evaporative demand of the two stands. Over the studied period of 2003, characterised by a severe drought episode during the summer, the oak stand (Ec was only 110 mm compared to the 239 mm transpired by the Scots pine stand, although the ratio of transpiration to reference evapotranspiration (Ec/ET0 in the oak stand compares well with the expected values predicted for low leaf area index (LAI oak forests in southern Europe. Scots pine showed a strong reduction in (Ec/ET0 as the drought developed, whereas pubescent oak was less affected by soil moisture deficits in the upper soil. As a second objective, and given the contrasting meteorological conditions between 2003 and 2004 summer periods, the interannual variability of transpiration was studied in the Scots pine plot. Rainfall during the summer months (June-September in 2003 was almost 40% less than in the same interval in 2004. Accordingly, transpiration was also reduced about 25% in 2003. Finally, Scots pine data from 2003 and 2004 was used to calibrate a simple transpiration model using ET0 and soil moisture deficit (SMD as input variables, and implicitly including stomatal responses to high vapour pressure deficits (Dd and soil water status.

  20. A novel stress-induced sugarcane gene confers tolerance to drought, salt and oxidative stress in transgenic tobacco plants.

    Directory of Open Access Journals (Sweden)

    Kevin Begcy

    Full Text Available BACKGROUND: Drought is a major abiotic stress that affects crop productivity worldwide. Sugarcane can withstand periods of water scarcity during the final stage of culm maturation, during which sucrose accumulation occurs. Meanwhile, prolonged periods of drought can cause severe plant losses. METHODOLOGY/PRINCIPAL FINDINGS: In a previous study, we evaluated the transcriptome of drought-stressed plants to better understand sugarcane responses to drought. Among the up-regulated genes was Scdr1 (sugarcane drought-responsive 1. The aim of the research reported here was to characterize this gene. Scdr1 encodes a putative protein containing 248 amino acids with a large number of proline (19% and cysteine (13% residues. Phylogenetic analysis showed that ScDR1is in a clade with homologs from other monocotyledonous plants, separate from those of dicotyledonous plants. The expression of Scdr1 in different varieties of sugarcane plants has not shown a clear association with drought tolerance. CONCLUSIONS/SIGNIFICANCE: The overexpression of Scdr1 in transgenic tobacco plants increased their tolerance to drought, salinity and oxidative stress, as demonstrated by increased photosynthesis, water content, biomass, germination rate, chlorophyll content and reduced accumulation of ROS. Physiological parameters, such as transpiration rate (E, net photosynthesis (A, stomatal conductance (gs and internal leaf CO(2 concentration, were less affected by abiotic stresses in transgenic Scdr1 plants compared with wild-type plants. Overall, our results indicated that Scdr1 conferred tolerance to multiple abiotic stresses, highlighting the potential of this gene for biotechnological applications.

  1. A novel stress-induced sugarcane gene confers tolerance to drought, salt and oxidative stress in transgenic tobacco plants.

    Science.gov (United States)

    Begcy, Kevin; Mariano, Eduardo D; Gentile, Agustina; Lembke, Carolina G; Zingaretti, Sonia Marli; Souza, Glaucia M; Menossi, Marcelo

    2012-01-01

    Drought is a major abiotic stress that affects crop productivity worldwide. Sugarcane can withstand periods of water scarcity during the final stage of culm maturation, during which sucrose accumulation occurs. Meanwhile, prolonged periods of drought can cause severe plant losses. In a previous study, we evaluated the transcriptome of drought-stressed plants to better understand sugarcane responses to drought. Among the up-regulated genes was Scdr1 (sugarcane drought-responsive 1). The aim of the research reported here was to characterize this gene. Scdr1 encodes a putative protein containing 248 amino acids with a large number of proline (19%) and cysteine (13%) residues. Phylogenetic analysis showed that ScDR1is in a clade with homologs from other monocotyledonous plants, separate from those of dicotyledonous plants. The expression of Scdr1 in different varieties of sugarcane plants has not shown a clear association with drought tolerance. The overexpression of Scdr1 in transgenic tobacco plants increased their tolerance to drought, salinity and oxidative stress, as demonstrated by increased photosynthesis, water content, biomass, germination rate, chlorophyll content and reduced accumulation of ROS. Physiological parameters, such as transpiration rate (E), net photosynthesis (A), stomatal conductance (gs) and internal leaf CO(2) concentration, were less affected by abiotic stresses in transgenic Scdr1 plants compared with wild-type plants. Overall, our results indicated that Scdr1 conferred tolerance to multiple abiotic stresses, highlighting the potential of this gene for biotechnological applications.

  2. Competition for light and water in a coupled soil-plant system

    Science.gov (United States)

    Manoli, Gabriele; Huang, Cheng-Wei; Bonetti, Sara; Domec, Jean-Christophe; Marani, Marco; Katul, Gabriel

    2017-10-01

    It is generally accepted that resource availability shapes the structure and function of many ecosystems. Within the soil-plant-atmosphere (SPA) system, resource availability fluctuates in space and time whereas access to resources by individuals is further impacted by plant-to-plant competition. Likewise, transport and transformation of resources within an individual plant is governed by numerous interacting biotic and abiotic processes. The work here explores the co-limitations on water losses and carbon uptake within the SPA arising from fluctuating resource availability and competition. In particular, the goal is to unfold the interplay between plant access and competition for water and light, as well as the impact of transport/redistribution processes on leaf-level carbon assimilation and water fluxes within forest stands. A framework is proposed that couples a three-dimensional representation of soil-root exchanges with a one-dimensional description of stem water flow and storage, canopy photosynthesis, and transpiration. The model links soil moisture redistribution, root water uptake, xylem water flow and storage, leaf potential and stomatal conductance as driven by supply and demand for water and carbon. The model is then used to investigate plant drought resilience of overstory-understory trees simultaneously competing for water and light. Simulation results reveal that understory-overstory interactions increase ecosystem resilience to drought (i.e. stand-level carbon assimilation rates and water fluxes can be sustained at lower root-zone soil water potentials). This resilience enhancement originates from reduced transpiration (due to shading) and hydraulic redistribution in soil supporting photosynthesis over prolonged periods of drought. In particular, the presence of different rooting systems generates localized hydraulic redistribution fluxes that sustain understory transpiration through overstory-understory interactions. Such complex SPA dynamics

  3. A role for ABA in the plants response to chitosan

    Directory of Open Access Journals (Sweden)

    Americo Rodrigues

    2014-06-01

    Full Text Available Chitosan is a biopolymer of glucosamine residue that can be produced by deacetylation of chitin present in seafood wastes such as shrimp or crab shell. Chitosan and its derivatives are nontoxic and biodegradable, and have been used in applications like cosmetics, medicine or agriculture. When used to enhance plant defenses, chitosan induces host defense responses in both monocotyledons and dicotyledons. These responses include lignification, chitinase and glucanase activation, phytoalexin biosynthesis, among others (El Hadrami et al., 2010. Reduction of plant leaves transpiration due to stomatal closure without affecting the photosynthetic rate or production yields has also been described in plants treated with chitosan. This effect was observed in different plants like bean (Phaseolus vulgaris(Khokon et al., 2010, pepper (Capsicum sp(Bittelli et al., 2001 or barley (Hordeum vulgare (Koers et al., 2011 among others. Abscisic acid (ABA plays a crucial role in the regulation of stomata aperture (Kim et al., 2010 but the role of this phytohormone in the chitosan induced stomatal closure is not clearly understood. Chitosan treatment of bean leaves triggers a 3 times increase in ABA content indicating an involvement of ABA in chitosan induced stomatal closure (Iriti et al., 2009. However, in Arabidopsis, aba2-2 mutants and wild type plants treated with an ABA biosynthesis inhibitor presented chitosan induced stomatal closure similar to wild type untreated plants suggesting that endogenous ABA is not required for this effect (Issak et al., 2013. The involvement of ABA in this process is also suggested by the observation that chitosan and ABA have convergent signaling components, like calcium and reactive oxygen species (Srivastava et al., 2009. The aim of this work is to better understand the role of ABA in chitosan induced stomatal closure, leading to a reduction of transpiration and concomitantly to higher water-use efficiency, using molecular and

  4. Comparing removal efficiency and reaction rates of organic micro-pollutants during ozonation from different municipal waste water treatment plants effluents in Sweden

    DEFF Research Database (Denmark)

    El-taliawy, Haitham; Ekblad, Maja; Nilsson, Filip

    2015-01-01

    The Removal of about 50 micro-pollutants from 7 waste water treatment plant effluents –in Sweden- was tested on pilot scale. Different ozone doses and two different pilots with different reactor sizes and retention times were tested. Ozone reaction rates depended on DOC concentration in the water...

  5. Changes in net photosynthesis, transpiration and dark respiration in winter barley exposed to elevated levels of sulphur dioxide using an open-air fumigation system

    Energy Technology Data Exchange (ETDEWEB)

    Darrall, N.M. (National Power Technology and Environmental Centre, Leatherhead (UK))

    1991-01-01

    Photosynthesis, transpiration and dark respiration were measured in winter barley (Hordeum vulgare L.) cv. 'Igri' exposed to sulphur dioxide (SO{sub 2}) in an open-air fumigation experiment during three growing seasons from 1985 to 1987. Observations were made on the most recently fully expanded leaves in situ using portable photosynthesis equipment with an integral logging facility. No long-term inhibition of photosynthesis was detected in response to elevated levels of SO{sub 2} of up to means of 0.043, 0.048 and 0.038 microliter l{sup {minus}1} during three experiments, respectively, but elevated rates of dark respiration were recorded in plots exposed to means of 0.032 and 0.043 microliter l{sup {minus}1} in 1985. Significantly enhanced rates of net photosynthesis were seen on the flag leaves in plots exposed to means of 0.021 and 0.043 microliter l{sup {minus}1} SO{sub 2} in 1985 and 0.014 and 0.048 microliter l{sup {minus}1} SO{sub 2} in 1986 where infestation with powdery mildew Erysiphe graminis DC ex Merat F. sp. hordei (Em Marchal) was also significantly greater of a percentage leaf area basis. The possible enhancement of leaf photosynthetic rates by mildew infestation of the lower leaves is discussed. No long-term reduction in the rate of transpiration or in stomatal conductance was detected, but simultaneous changes were observed in these two parameters in the same direction, as short-term incrases or decreases in photosynthesis. 6 figs., 29 refs., 3 tabs.

  6. Scaling up and error analysis of transpiration for Populus euphratica in a desert riparian forest

    Science.gov (United States)

    Si, J.; Li, W.; Feng, Q.

    2013-12-01

    Water consumption information of the forest stand is the most important factor for regional water resources management. However, water consumption of individual trees are usually measured based on the limited sample trees , so, it is an important issue how to realize eventual scaling up of data from a series of sample trees to entire stand. Estimation of sap flow flux density (Fd) and stand sapwood area (AS-stand) are among the most critical factors for determining forest stand transpiration using sap flow measurement. To estimate Fd, the various links in sap flow technology have great impact on the measurement of sap flow, to estimate AS-stand, an appropriate indirect technique for measuring each tree sapwood area (AS-tree) is required, because it is impossible to measure the AS-tree of all trees in a forest stand. In this study, Fd was measured in 2 mature P. euphratic trees at several radial depths, 0~10, 10~30mm, using sap flow sensors with the heat ratio method, the relationship model between AS-tree and stem diameter (DBH), growth model of AS-tree were established, using investigative original data of DBH, tree-age, and AS-tree. The results revealed that it can achieve scaling up of transpiration from sample trees to entire forest stand using AS-tree and Fd, however, the transpiration of forest stand (E) will be overvalued by 12.6% if using Fd of 0~10mm, and it will be underestimated by 25.3% if using Fd of 10~30mm, it implied that major uncertainties in mean stand Fd estimations are caused by radial variations in Fd. E will be obviously overvalued when the AS-stand is constant, this result imply that it is the key to improve the prediction accuracy that how to simulate the AS-stand changes in the day scale; They also showed that the potential errors in transpiration with a sample size of approximately ≥30 were almost stable for P.euphrtica, this suggests that to make an allometric equation it might be necessary to sample at least 30 trees.

  7. Fundamental study of transpiration cooling. [pressure drop and heat transfer data from porous metals

    Science.gov (United States)

    Koh, J. C. Y.; Dutton, J. L.; Benson, B. A.

    1973-01-01

    Isothermal and non-isothermal pressure drop data and heat transfer data generated on porous 304L stainless steel wire forms, sintered spherical stainless steel powder, and sintered spherical OFHC copper powder are reported and correlated. Pressure drop data was collected over a temperature range from 500 R to 2000 R and heat transfer data collected over a heat flux range from 5 to 15 BTU/in2/sec. It was found that flow data could be correlated independently of transpirant temperature and type (i.e., H2, N2). It was also found that no simple relation between heat transfer coefficient and specimen porosity was obtainable.

  8. Transpiration and hydraulic strategies in a piñon-juniper woodland.

    Science.gov (United States)

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

    2008-06-01

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

  9. Control of Leaf Expansion by Nitrogen Nutrition in Sunflower Plants : ROLE OF HYDRAULIC CONDUCTIVITY AND TURGOR.

    Science.gov (United States)

    Radin, J W; Boyer, J S

    1982-04-01

    Nitrogen nutrition strongly affected the growth rate of young sunflower (Helianthus annuus L.) leaves. When plants were grown from seed on either of two levels of N availability, a 33% decrease in tissue N of expanding leaves was associated with a 75% overall inhibition of leaf growth. Almost all of the growth inhibition resulted from a depression of the daytime growth rate. Measurements of pressure-induced water flux through roots showed that N deficiency decreased root hydraulic conductivity by about half. Thus, N deficiency lowered the steady-state water potential of expanding leaves during the daytime when transpiration was occurring. As a result, N-deficient leaves were unable to maintain adequate turgor for growth in the daytime. N deficiency also decreased the hydraulic conductivity for water movement into expanding leaf cells in the absence of transpiration, but growth inhibition at night was much less than in the daytime. N nutrition had no detectable effects on plastic extensibility or the threshold turgor for growth.

  10. Photosynthesis is induced in rice plants that associate with arbuscular mycorrhizal fungi and are grown under arsenate and arsenite stress.

    Science.gov (United States)

    de Andrade, Sara Adrian Lopez; Domingues, Adilson Pereira; Mazzafera, Paulo

    2015-09-01

    The metalloid arsenic (As) increases in agricultural soils because of anthropogenic activities and may have phytotoxic effects depending on the available concentrations. Plant performance can be improved by arbuscular mycorrhiza (AM) association under challenging conditions, such as those caused by excessive soil As levels. In this study, the influence of AM on CO2 assimilation, chlorophyll a fluorescence, SPAD-chlorophyll contents and plant growth was investigated in rice plants exposed to arsenate (AsV) or arsenite (AsIII) and inoculated or not with Rhizophagus irregularis. Under AsV and AsIII exposure, AM rice plants had greater biomass accumulation and relative chlorophyll content, increased water-use efficiency, higher carbon assimilation rate and higher stomatal conductance and transpiration rates than non-AM rice plants did. Chlorophyll a fluorescence analysis revealed significant differences in the response of AM-associated and -non-associated plants to As. Mycorrhization increased the maximum and actual quantum yields of photosystem II and the electron transport rate, maintaining higher values even under As exposure. Apart from the negative effects of AsV and AsIII on the photosynthetic rates and PSII efficiency in rice leaves, taken together, these results indicate that AM is able to sustain higher rice photosynthesis efficiency even under elevated As concentrations, especially when As is present as AsV.

  11. 干燥密罗木复水过程中光诱导蒸腾拉力变化与复水时间的关系%The Relationship Between Light-induced Changes in Transpiration Pull and Rehydration Times in Desiccated Myrothamnus flabellifolia

    Institute of Scientific and Technical Information of China (English)

    朱建军; 刘林德; 朱路英

    2013-01-01

    该文探讨了干燥脱水后的复苏植物密罗木(Myrothamnus flabellifolia)的复水速度和复水后不同时间下的木质部压力与植物对光-暗反应的关系.研究结果表明,密罗木整株植物和离体枝条复水时水分在茎内的上升速度都很快,10小时左右水分即可接近枝条的顶端.在植物复水初期,木质部压力反应随着复水时间的延长不断增加,3周后达到正常值.这种木质部压力的调节能力可能与气孔功能的恢复程度有关.同时,密罗木在整个复水恢复过程中受到光照时木质部压力下降的弛豫时间都明显大于植物在光源关闭时木质部压力上升的弛豫时间.表明密罗木对蒸腾速率上升过程的调节速度明显低于对蒸腾速率下降过程的调节速度.%We investigated the rate of water ascent and time course of xylem pressure in response to light or darkness in the rehydrated resurrection plant Myrothamnus flabellifolia.The time for water to rise to the apex of an intact or detached desiccated twig was about 10 h,whereas the time for full recovery of the regulation of xylem pressure response to light or darkness was about 3 weeks.The recovery of the pressure regulation should be associated with the recovery and function of stomata in desiccated leaves after rehydration.In addition,the relaxation time of xylem pressure decline in response to light was significantly longer than that of xylem pressure ascent in response to darkness,so the regulation rate of the plant to transpiration increase induced by light was significantly lower than that to transpiration decline induced by darkness.

  12. The differential effects of CO{sub 2} on relative growth rates of a C{sub 3} and C{sub 4} plant

    Energy Technology Data Exchange (ETDEWEB)

    Grise, D.J.; Sage, R.F. [Univ. of Georgia, Athens, GA (United States)]|[Univ. of Toronto, Ontario (Canada)

    1995-09-01

    We examined growth and allocation in Chenopodium album (C{sub 3}) and Amaranthus hybridus (C{sub 4}) at three CO{sub 2} levels (350, 750 and 1000 {mu}bar CO{sub 2}), at 34{degrees}C. Although net assimilation rate increased at