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1
Khalil, Ayoub Adam Mohammed. "Water relations of young trees." Thesis, University of Edinburgh, 1993. http://hdl.handle.net/1842/10982.
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The morphological and physiological responses of tree seedlings to water stress and the significance of the non-hydraulic influence of root on shoot behaviour of the effects of soil drying were investigated. The experiments were conducted in a glasshouse and growth chamber, using sycamore (Acer pseudoplatanus L.) seedlings rooted in a soil mixture with high water holding capacity. The prime objective of the project was to evaluate the morphological and physiological components of drought tolerance that could be useful for isolation of plants with seedling characteristics acceptable for afforestation in drought-prone environments. Effects of drought on water relations and root growth were studied using long soil columns. Drought resulted in active osmotic adjustment in leaves, with decreases in osmotic potential at full and zero turgor, and it increased bulk elastic modulus and leaf dry weight to turgid weight ratio. Stomatal conductance declined well before any observable change in bulk leaf water potential and was correlated with soil water status. Drought caused changes in the root distribution profile and it increased the root weight. The increase in root weight was mainly due to a substantial shift in assimilates allocated in favour of roots with total biomass being unaffected. Cyclic water stress treatment, induced major changes in sycamore seedlings, including osmotic adjustment, acclimation of photosynthesis and stomatal conductance to water stress, increased water use efficiency, and a substantial shift in biomass allocation pattern in favour of roots, with a consequent increase in root/shoot ratio. The acclimation of photosynthetic machinery was the major factor contributing to the acclimation of photosynthesis to water stress. These modifications were concluded to be important for improvement of seedling drought tolerance. Seedlings grown in soil columns and subjected to drought exhibited substantial reduction in stomatal conductance and a limitation in leaf expansion well in advance of any detectable change in shoot water relations. Root abscisic acid (ABA) concentration increased deeper in the soil profile in concert with the progressive soil drying, and it appeared to be a sensitive indicator of the soil water status around the roots.
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Arif, Hamayun. "Water relations of salt stressed wheat." Thesis, Bangor University, 1990. https://research.bangor.ac.uk/portal/en/theses/water-relations-of-salt-stressed-wheat(b523794e-42f4-4165-bb35-11f07b7bbf28).html.
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The present study was conducted to investigate the water relations of individual plant cells and the biophysical parameters controlling plant growth in the context of salt stress. Growth and water relations were studied in growing as well as in mature zones of the first emerged leaf of wheat seedlings (cv. Flanders, a British variety) in the context of NaCl stress. Various levels of NaCl (0,25,50,75,100,125 and 150 mol m) -3 were used to salinize the media. I In the case of leaf elongation rate a two phase response was found i. e. an immediate decrease and then, a recovery in the elongation rate. Leaf elongation rate decreased within 1-2 minutes of the onset of stress and, later, a recovery started 1-2 h after the salt addition. The time taken for the recovery was proportional to the levels of external salinity. After 24 h the elongation rate was almost fully recovered for all the NaCl concentrations. A similar response was observed when equi-osmolar concentrations (with NaCl) of mannitol were added to the media. In control plants turgor pressure of the expanding cells was about 0.45 MPa while tissue osmotic pressure was equal to 1.1 MPa showing that the cell had a low water potential (-0.6 MPa). The transpiration tension was equivalent to 0.1 MPa. Turgor pressure in th e growing cells did not change after the salt addition (0- 150 mol m-3 NaCl), however, the tissue osmotic pressure continuously increased with time. Turgor pressure dropped when more -3 than 150 mol m NaCl were applied to the media i. e. 200 and 250 mol m. -3 This is presented as evidence that growing leaf cells - maintained their turgor pressure In response. to . the salt stress by taking up osmotically -active solutes present in the cell wall. The salt stress had not any effect on Instron tensiometric measurements of elastic and plastic extension of the cell wall. A different turgor pressure response was found in the mature cells. Turgor pressure was about 1.0 MPa, almost twice that in the growing cells, while tissue osmotic pressure was similar to that found in the growing cells i. e. 1.1 MPa. After the application of the stress the turgor pressure dropped within 15- 20 min of the application of all the concentrations of NaCl. The osmotic pressure of osmotically active solutes present in the cell wall, nwr was almost negligible i. e. 4 0.1 MPa, in mature cells and so could not contribute to turgor maiýtenance. The extent of decrease was proportional to the external stress of 25, 50 and 75 mol m-3 NaCl only. Turgor pressure recovery, due to osmotic adjustment, started after about 10-12 h of the stress initiation. Complete turgor recovery was achieved after 24-48 h of the onset of stress depending on the applied NaCl concentration. Tissue osmotic pressure increased continuously with time. An increase in the nw was inferred during the whole experimental period and after 6d of the stress application that appeared to correspond to the magnitude of external stress. The concentrations of major ions and sugars were determined to measure their contribution towards the osmotic adjustment. Under control conditions Na +, ci-, PO 4 3- ' so 4 2- , glucose, fructose and sucrose were present in small amounts, while, K+ and No 3- were the-major osmotica. Their concentrations were about 200. mol _m-3. After the stress a large increase in the concentrations of Na + and Cl was observed, the sucrose concentration increased to a small extent. However, other osmotica remained Uniform for whole of the experimental time. A small decrease was observed in k+ concentration in response to higher salt levels. volumetric elastic modulus, -c, of mature cells was remained unchanged by the salt stress. However, the apparent resistance of the root cortex to osmotically driven water flow increased with the increase in stress level. No conclusion could be drawn about the contribution of these parameters to the control of growth and to leaf water relations in the context of salt stress. The possible use of turgor pressure recovery in the mature cells was investigated for assessing the extent of salt tolerance of various Pakistani wheat varieties. These varieties were previously rated according to their performance in absolute grain yield in response to NaCl stress. No simple correlation was found.
3
Hart, Miranda M. "Compensatory water relations in aspen following defoliation." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/MQ34374.pdf.
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Hukin, David James John. "Water relations and biophysics of plant cells." Thesis, University of Birmingham, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.398699.
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Trocsanyi, Zsuzsa. "Water relations and cutting management of switchgrass." Diss., Virginia Tech, 1990. http://hdl.handle.net/10919/39760.
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Vieux, Micah Steven. "AN INTERNSHIP IN WATER UTILITY STAKEHOLDER RELATIONS." Miami University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=miami1368017965.
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Hernandez-Leos, Bertha Alicia. "Water Uptake, Water Relations, Tree Growth, and Root Distribution under Herbaceous Competition." DigitalCommons@USU, 1998. https://digitalcommons.usu.edu/etd/6573.
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There are numerous situations where trees are grown together with herbaceous plants. In these situations there will be some degree of competition between their root zones, depending on the water content of the soils and crop and tree root distribution . Two studies were conducted : the first with maple (Acer platanoides) grown in turf grass, and the second with willow (Salix matsudana) grown in more deeply rooted barley . The objectives of this study were to quantify the effect of herbaceous competition of potential tree water stress under irrigation and when the soil is allowed to dry-down . Soil water uptake was measured in both studies to 1.2 m depth and outwards to 1.2-2.10 m away from the tree . In the maple-turf grass study, water content was measured in a single line away from the tree , while four lines covering a quadrant of the surface area were measured in willow . Water relations stomatal conductance and water potential, and tree growth were also monitored in both studies. Water uptake in turf plots was statistically different from mulch plots by depth and distance during three seasons. Water uptake was greatest at 0-60 cm depth in the turf treatments compared with mulch treatments. Soil water in mulched plots decreased slowly during the growing season. There were no statistical differences between bare soil and barley competition water uptake after soil surface water was depleted.
There were marked differences in tree root characteristics as a result of competition from turf or barley roots. The root systems of maples in the mulch and willow in bare soil extended laterally and fine roots were evident. Tree roots extended deeper and fine root were reduced under competition from turf and barley. Trees growing with turf and barley had fewer roots in the top 0.3 m soil surface while trees in mulch and bare soil had more and greater diameter roots at the same depth. Early in the season, when water content is high, root competition for water was not evident, and late in the season after turf roots and barley had depleted the soil water, trees exhibited more negative predawn leaf water potential and less stomatal conductance in response to water stress during a soil dry-down period. Tree growth was measured periodically during 1994, 1995, and 1996. Leaf area and stem growth comparisons showed a significant increase in size as a result of the absence of competition in both species, with mulch and bare soil treatments. Leaf area in mulched trees was twice that in turf treatments. In summary, we found that competition resulted in deeper tree root growth and less top growth in the presence of herbaceous competitors.
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Heinmiller, B. Timothy Sproule-Jones Mark. "Partners and competitors : intergovernmental relations and the governance of transboundary common pools /." *McMaster only, 2004.
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Molloy, Shannon. "Sugar transport and water relations of Agaricus bisporus." Thesis, Cranfield University, 2004. http://hdl.handle.net/1826/797.
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The A. bisporus fruit body can develop from a 0.5 cm primordium to a 7 cm fruit body within 6 days and it is this rapid growth and expansion which was investigated. The mycelium and fruit body extract water and solutes from the compost and casing soil. Water and solute translocation is thought to occur by osmotically derived pressure driven mass flow whereby the accumulation of the polyol mannitol in the fruit body lowers the water potential and allows for an influx of water which increases the turgor pressure and creates a turgor gradient thus driving water and solutes into the mycelium. This work investigated the mechanism of water and sugar translocation through the mycelium and into the developing sporophore and the factors which affect this translocation path. The effect of different water stresses (osmotic and matric) on mycelial growth, osmotic, turgor and water potential and the accumulation of endogenous sugars and polyols when grown on two different media: a defined malt extract and compost derived was investigated. The concentration of various sugars and polyols was measured in the following sporophore tissue: cap, gills, skin and upper and lower stipe. A sugar transporter gene SUT1 which had previously been identified in A. bisporus was fully characterised.
The mycelium was most sensitive to changes in matric than osmotic potential on malt extract agar (MEA) medium and there was no mycelial growth below -0.98 MPa on matrically modified medium but the mycelium continued to grow at water stresses of -1.48 and -2.48 MPa on osmotically modified MEA medium. However on compost derived medium less difference was found between osmotic and matric stresses. The following sugars: glucose and trehalose and the polyols: mannitol, glycerol and erythritol were quantified in the mycelium and mannitol was found to be the dominant polyol which increased with increasing water stress in the mycelium. However in mycelium grown on matrically modified compost media at -0.48 and -0.98 MPa the mannitol levels didn’t increase with increasing water stress and this was reflected by the mycelium having a lower internal water potential than the external medium indicating that the mycelial tolerance to matric stresses is linked to the components of the compost as no such tolerance was found on MEA medium.
Mannitol was the main polyol detected in all the sporophore tissues but there were no significant differences between the stages of sporophore development indicating that there was no change in the levels of mannitol. Previous reports by Hammond and Nichols (1976) and Wannet et al. (2000) have shown that the level of mannitol increased during sporophore development but the difference could be attributed to the casing soil which is now wetter and therefore the sporophore is not under increasing water stress and can extract water without having to constantly adjust its polyol concentration.
The SUT1 protein had a predicted molecular weight of 61.2 kDa and according to topology predictions had 12 transmembrane domains and a number of highly conserved regions which place it in the sugar transporter family of the major facilitator superfamily. The level of SUT1 transcript increased during sporophore development and there were higher but equal levels of SUT1 transcript in the upper and lower stipe compared to the cap, gills and skin tissue (indicated by Northern analysis). However no SUT1 transcript could be detected in the mycelium supporting stage 2 and 4 sporophore development indicating that it is possibly involved in translocation in the fruit body but not in the mycelium. The detection of the SUT1 protein by Westerns was attempted using an antibody raised to the SUT1 C-terminal region. However the extraction and solubilisation of the membrane bound SUT1 protein proved very difficult and was not successfully detected by Westerns.
10
Hadjiloucas, Sillas. "Optical sensors and techniques for plant-water relations." Thesis, University of Reading, 1996. http://centaur.reading.ac.uk/18980/.
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Mohiuddin, Mohammed. "Plant water relations in a model agroforestry system." Thesis, University of Edinburgh, 1992. http://hdl.handle.net/1842/11174.
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This study reports the results of experiments on growth and physiology of an agricultural annual (French bean) and a young tree (poplar) in relation to limited soil water. Competition and complementarity between the species were evaluated in a model agroforestry experiment. The experiments were carried out in a greenhouse and growth cabinet with plants grown in pots containing sandy-loam compost. The species studied were Phaseolus vulgaris cv. Argus and Populus trichocarpa X P. deltoides cv. Raspalje. The main aim of the study was to characterise the responses of both species to different soil water supply regimes, shoot water supply by roots and chemical signalling from the roots in drying soil and to show how these responses could be used in the selection of suitable agroforestry for dry regions. Bean and poplar plants showed differential growth responses although both the species performed better in mixed stands than in monoculture when soil water was severely limited. Beanplants were more competitive than poplar, although both species showed complementarity in exploration for soil water. As the soil dried leaf water potential declined. Stomatal conductance of both species was more closely related to pre-dawn leaf water potential than to mid-day leaf water potential, indicating the importance of soil water status. Experiments with both vertically and horizontally divided root systems showed that bean and poplar plants with at least half of their root system in moist soil were able to maintain leaf water status as well as plants with all their root systems in moist soil. Furthermore, stomatal conductance and leaf expansion of both species were affected directly by soil drying independent of leaf water potential.
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Damaske, Michael Andreas Christian. "Water relations in mango (Mangifera indica L.) trees." Diss., University of Pretoria, 2010. http://hdl.handle.net/2263/28875.
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Goodchild, A. J. P. "Contributions to knowledge of water relations in Hemiptera." Thesis, University of Bath, 1988. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.384120.
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Bell, Brian P. "Growth and Water Relations of Native Wheatgrass Populations." DigitalCommons@USU, 2008. https://digitalcommons.usu.edu/etd/7499.
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Screening populations for development into released plant materials can be done inexpensively and in a timely manner. A common approach has been to quantify the amount of shoot dry mass produced as a surrogate for competitiveness. Besides dry mass production , other morphological characteristics have been employed , but physiological parameters have received less emphasis. Dry mass production may be an important characteristic, but identifying the traits responsible can be just as imperative . Populations with greater drought tolerance may be less impacted by competition for water from weeds, which could lead to greater establishment of desirable grasses on disturbed landscapes.
The objective for chapter 2 was to evaluate the effects of cheatgrass competition on the growth and water relations of three Snake River wheatgrass (Elymus wawawaiensis) populations and two bluebunch wheatgrass (Pseudoroegneria spicata) populations in the seedling stage in a greenhouse setting. The treatments were 1) containers with a single wheatgrass plant or 2) containers with one wheatgrass and one cheatgrass plant. Containers were watered gravimetrically to 11.5% soil-water content, regard less of treatment, every few days until harvested on day 35. Cheatgrass competition reduced root dry mass, shoot dry mass, leaf area, leaf number, tiller number, xylem pressure potential, and stomata} conductance. The bluebunch wheatgrass populations generally had more negative xylem pressure potential, higher stomata! conductance, and higher shoot dry mass, while the Snake River populations had higher specific leaf area and less negative xylem pressure potentials .
The objective for chapter 3 was to evaluate the effects of planting density on the growth and water relations over a 2-year period among five Snake River wheatgrass populations, one thickspike wheatgrass (Elymus lanceolatus) population , and three interspecific hybrids. High (25 plants/m 2 ) and low-density (7.8 plants/m2) plots of each grass were transplanted to Millville, Utah in the spring of 2005 and 2006 intended to generate low and high resource availability environments, respectively. Thickspike wheatgrass had the highest shoot dry mass and least negative xylem pressure potential , the hybrids were intermediate, and the Snake River wheatgrasses were least productive and more water stressed.
The primary benefit of this thesis will be through identifying the potential for developing these populations into improved plant materials and releasing them for commercial use in degraded rangelands across the Intermountain West. These new plant materials may also help transition damaged rangelands towards more desirable stable states composed of lower abundances of invasive annual grasses.
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Bonner, Donald M. "Comparative water relations and drought tolerance among alfalfa cultivars." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/mq23227.pdf.
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Wikberg, Jenny. "Water relations in Salix with focus on drought responses /." Umeå : Department of Forest Genetics and Plant physiology, Swedish University of Agricultural Sciences, 2006. http://epsilon.slu.se/200648.pdf.
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Griffiths, Allen. "Abscisic acid and the water relations of tomato roots." Thesis, Bangor University, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.306779.
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Zafiropoulos, Apostolos. "Prospects for studying plant water relations using THz technology." Thesis, University of Reading, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.502493.
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Taking into consideration tlie current understanding of the biophysical processes encountered in plants, expressions for the water potential at the cellular and tissue level as well as in the immediate environment around a canopy have been clarified. A critical review of the different THz technologies is provided and conclusions are made on the suitability of different measurement systems for noninvasively monitoring the water status of plants. Broadband spectrometric measurements of leafwater content are provided to demonstrate the advantage of operating at this part of the spectrum. Elaborate null-balance bridge techniques are discussed in detail as these can provide a measure of absolute reflectance or transmittance from the sample. A discussion of an automated (microprocessor based) procedure for finding the nulls corresponding to a balanced state of the instrument is provided. The performance limits of the automated reflectometer are discussed by performing measurements on several samples spanning the entire range of possible reflectivities. The errors from the balancing procedure are propagated to the leaf water content index so as to establish the levels of performance required for such instrument to be useful to plant scientists. Additional errors related to this balancing procedure due to the diffractive spreading of the beam in the sample arm of the interfermeter before reported in the literature are provided. Furthermore, a new leaf-water-content index is suggested as a way of relating leaf relative water content to THz reflectance directly. It is explained that provided additional equipment is available, the above parameters can provide estimates of leaf water potential, solute or matric potential and volumetric elastic modulus of the cells.
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Noakes, Timothy David. "Water relations of mosses from maritime Antarctic cryptogamic fellfields." Thesis, University of Reading, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.315302.
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Ellis, Warren. "Grapevine (Shiraz/Richter 99) water relations during berry ripening." Thesis, Stellenbosch : Stellenbosch University, 2008. http://hdl.handle.net/10019.1/2328.
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Thesis (MscAgric (Viticulture and Oenology))--Stellenbosch University, 2008.The effect of various irrigation strategies on grapevine water relations during the berry ripening period was investigated in a Shiraz/Richter 99 vineyard. Comparisons between different irrigation strategies (full/seasonal, véraison+post véraison, post véraison and no irrigation) were made. During the day, the seasonally irrigated vines experienced less water stress than the deficit treatments. Non-irrigated vines seemed to maintain higher diurnal leaf water potentials. Lower leaf water potentials indicated lower water contents in the vegetative and reproductive tissue. Full irrigation seemed to stimulate primary shoot length. Longer water deficit induced earlier and more complete shoot maturation (reserve accumulation). Re-distribution of leaf area on the shoot may occur when vines are subjected to water deficit. Extended water deficit seemed to induce earlier and restricted water loss from vegetative tissue. The water relations were reflected in the berry size. Irrigation during ripening seemed to induce a continuation of berry water loss. Transpiration losses were apparently much higher in fully irrigated vines whereas stomatal control efficiently maintained water relations in non-irrigated vines. Water deficit seemed to have enhanced the soluble solid accumulation. Irrigation treatments did not seem to affect the titratable acid and pH. The post véraison irrigation in particular seemed to favour a wide window for harvesting. Irrigation at post véraison and especially véraison+post veraison seemed to have a greater effect on the synthesis and extraction of phenolics, anthocyanins and tannins in the berry skins. Different irrigation strategies may affect grapes in such a way that different wine styles are obtained.
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Pellegrino, Antonio 1959. "Water relations of Vitis vinifera L. c.v. 'Cabernet Sauvignon'." Thesis, The University of Arizona, 1987. http://hdl.handle.net/10150/191939.
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Evapotranspiration measured from two Vitis vinifera L. c.v. 'Cabernet Sauvignon' by the water budget method totaled 136.1 1 d⁻¹, and steady state leaf transpiration rates averaged 57 ± 47 mg m⁻² s⁻¹ from March to August 1986 in Oracle, Arizona. Rooted cuttings were subjected to four levels of water stress in the greenhouse by withholding water. Pot weight variation was correlated to soil water potential by thermocouple psychrometry. Mesophyll conductance and CO₂ assimilation, measured with an open gas exchange system, were decreased by 80 and 70%, respectively, indicating severe limitations imposed by water stress on photosynthesis for this cultivar.
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Van, Metre Peter Chapman 1956, and Metre Peter Chapman 1956 Van. "Flow and water quality relations between surface water and ground water in the Puerco River basin near Chambers, Arizona." Thesis, The University of Arizona, 1990. http://hdl.handle.net/10150/277926.
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The Puerco River is an ephemeral stream that received effluent from uranium-mine dewatering operations from the 1950's until 1962 and from 1968 until mining ceased in 1986. Flow and water-quality relations between the Puerco River and the alluvial aquifer underlying it were investigated at a site near Chambers. Data collection included installing and sampling nine monitor wells and two drive points; monitoring stage and sampling surface water; and slug testing wells. The stream recharges the alluvial aquifer during periods of flow and the streambed is a location of ground-water discharge by evapotranspiration during periods of no flow. Discharge by evapotranspiration may exceed recharge thus reducing the potential for contaminant movement away from the river by advective transport. Geochemical modeling indicates that uranium minerals are undersaturated in the range in Eh observed. A +0.84 correlation was calculated relating dissolved uranium concentration to depth in monitor wells suggesting the stream is a source of uranium to the alluvial aquifer. (Abstract shortened with permission of author.)
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Gindaba, Jiregna. "Water and nutrient relations of selected tree species of Ethiopia." Thesis, Stellenbosch : University of Stellenbosch, 2004. http://hdl.handle.net/10019.1/16050.
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Dissertation (PhD (Bosb))--University of Stellenbosch, 2003.ENGLISH ABSTRACT: This study was conducted to evaluate and compare the water and nutrient relations of three indigenous deciduous tree species, viz., Cordia africana Lam., Croton macrostachyus Del., Millettia ferruginea (Hochst.) Baker and two widely planted eucalypts, viz., Eucalyptus camaldulensis Dehnh and Eucalyptus globulus Labill from Ethiopia. The study was organized as glasshouse and field observations in Ethiopia. Owing to the lack of baseline studies on the water and nutrient relations of the deciduous tree species, the glasshouse experiments involved a wide range of water and nutrient applications. Seedlings were grown with the supply of various levels of water and nutrients during which gas exchange, water potential, relative water content, tissue nutrient content and biomass production were measured. The field observations were limited to the study of surface root distribution and leaf nutrient composition of mature trees and their effects on soil nutrient pool. The observations were made on isolated trees and mixed or pure stands of trees in Badessa area, Eastern Ethiopia. The field site was selected because of the availability of the study species and suitability of the trees for the study. In the glasshouse, increased water deficit significantly reduced predawn leaf water potential, relative water content, stomatal conductance, photosynthetic rate, whole plant water use efficiency, plant height, diameter, leaf area and biomass production. Both of the eucalypts did not grow faster than the deciduous species under well-watered conditions unlike under water stress conditions. C. macrostachyus and C. africana had higher transpiration rates and tissue nutrient accumulations than the other species. They also demonstrated higher biomass allocation to roots than all the other species to support the intensive water and nutrient uptake rate. Due to the ability to re-orient its leaves to avoid direct solar irradiance, M. ferruginea maintained higher tissue water potential and relative water content than all the other species under water stress regimes. The impact of imposed drought was quick and more damaging to the eucalypts compared to the deciduous tree species indicating that the eucalypts may not survive extreme drought conditions unlike the deciduous species that drop their leaves and may remain dormant for weeks. The current study gave new experimental proof that E. globulus was more vulnerable to drought than E. camaldulensis. Soil N stress resulted in an overall reduction of tissue N concentration, N:P ratio, photosynthetic rate, stomatal conductance and photosynthetic water use efficiency in all the species studied. Pants with high foliar nitrogen concentration had higher photosynthetic capacities indicating that N plays a key role in photosynthesis and growth of all the studied species. The current study showed that for all the tree species, more attention has to be given to soil N than to P as soil P had minor effects on the photosynthetic activities of plants of all species compared to N.The investigation on tissue nutrient composition confirmed that N:P ratio could be used to detect Plimitation in plants. However, N:P ratio could not distinguish between N-limitation and combined limitations of N and P. The study of isolated C. africana and C. macrostachyus trees on soils in Badessa, Eastern Ethiopia indicated improved soil N, P and K under tree canopies whereas no effects were observed on the other soil nutrients studied. Similar to glasshouse conditions, C. macrostachyus and C. africana produced extensive surface roots, interfering with crops grown in association. Due to their high nutrient cycling potential the net effect on soil was positive. Comparison of E. camaldulensis woodlot and a mixed stand composed of deciduous species indicated that the fine root biomass in the surface soil under E. camaldulensis was about three times that under the mixed stand. The fine root biomass of E. camaldulensis inside the stand and 10 meters away from the stand were comparable in the surface soils showing the presence of root competition with adjacent crops. Therefore, planting of E. camaldulensis in association or adjacent to croplands should be avoided. Nutrient and carbon pool of soil inside the mixed stand was generally higher than that of E. camaldulensis indicating that trees of the mixed stand recycled more nutrients to the soil.
AFRIKAANSE OPSOMMING: Die doel van hierdie studie was om die verskille tussen water- en voedingstofverhoudings van drie inheemse blaarwisselemde boomsoorte te vergelyk, viz., Cordia africana Lam., Croton macrostachyus Del., Millettia ferruginea (Hochst.) Baker en twee bekende eucalyptus spesies, viz., Eucalyptus camaldulensis Dehnh en Eucalyptus globulus Labil van Etiopië. Die studie het bestaan uit kweekhuis- en veldobservasies in Etiopië. As gevolg van beperkte navorsing ten opsigte van water- en voedingstofverhoudings in bladwisselende boomsoorte, het die kweekhuis-eksperimente bestaan uit 'n wye verkeidenheid water- en voedingstoftoetse. Saailinge is gegroei deur verskillende vlakke van water- en voedingstowwe by te voeg. Gaswisseling, waterpotensiaal, relatiewe hoeveelheid water, hoeveelheid voedingstowwe en produksie van biomassa is gemeet. Die veldobservasies was beperk tot oppervlak-wortelverspreiding en blaarvoedingstof hoeveelhede van volwasse bome, sowel as die effek op grondvoedingstowwe. Observasies was beperk tot geïsoleerde, gemengde en een spesie opstande, in die Badessa area, Oos Etiopië. Die studiearea was gekies op grond van die voorkoms van die gekose boomsoorte, sowel as die toepaslikheid van die bome vir die studie. In die kweekhuis is gevind dat die verhoogte watertekort die pre-sonop blaarwaterpotensiaal, relatiewe hoeveelheid water, stomatiese geleiding, fotosintetiese tempo, heelplant water-gebruikseffektiwiteit, plant hoogte, diameter, blaararea en biomassa produksie beduidend verminder het. Nie een van die eucalyptus spesies het vinniger as die bladwisselende spesies onder voldoende hidrasie gegroei nie. Dit was egter nie die geval onder die waterbeperkte toestande nie. C. macrostachyus en C. africana het ‘n hoër transpirasie tempo sowel as weefselvoedingstof waardes gehad as die ander spesies. Hierdie boomsoorte se wortelbiomassa was ook meer as die ander spesies, om vir die tempo van water- en voedingstofopname te akkomodeer. As gevolg van die vermoë om blare te kan oriënteer om direkte sonlig te vookom, het M. ferruginea ‘n hoër water-weefselpotensiaal en relatiewe waterinname gehad in vergelyking met die ander boomsoorte in beperkte water toestande. Die impak van gëinisieerde droogte het vinnig voorgekom en het meer skade aan die eucalyptus aangerig in vergelyking met die bladwisselende boomsoorte. Dit dui aan dat die eucalyptus-spesie nie ekstreme droogte kan oorleef nie, waar bladwisselende spesies hul blare laat afval en vir weke aan een dormant kan bly. Hierdie studie gee eksperimentele bewyse dat E. globulus minder bestand is teen droogte as E. camaldulensis. Beperkte N in die grond het veroorsaak dat daar ‘n algemene vermindering van weefsel Nkonsentrasie, N:P ratio, fotosintetiese tempo, stomatiese geleiding en fotosintetiese watergebruiks effektiwiteit in al die bestudeerde spesies was. Plante wat oor hoër blaar-stikstofkonsentrasiesbeskik, het hoër fotosintetiese kapasiteite wat aandui dat N ‘n belangrike rol in fotosintese en die groei van al die bestudeerde spesies speel. Die oorhoofse bevindings van die studie was, dat daar meer aandag gegee moet word aan grond-N as P omdat grond-P net ‘n kleiner rol speel in die fotosintetiese aktiwiteite van plante van al die spesies in vergelyking met N. Die ondersoek na weefselvoedingstof hoeveelhede het bewys dat die N:P ratio gebruik kan word om P-tekorte in plante aan te dui. Die N:P ratio kan egter nie die verskil in N-tekorte en gekombineerde tekorte van N en P aandui nie. Die studie van die geïsoleerde C. africana en C. macrostachyus bome op grondtipes in Badessa, Oos Etiopië het verbeterde grond-N, P en K onder kroondak gebiede getoon, daar was egter geen verskille in die ander grondvoedingstowwe wat bestudeer is nie. In toestande gelykstaande aan die van die kweekhuis, het C. macrostachyus en C. africana meer oppervlaksswortels ontwikkel. Die toename aan oppervlakswortels het ingedring op gewasse wat in assosiasie gegroei is, dit het egter ‘n positiewe effek op die grond gehad as gevolg van die hoë voedingstof-siklus-potensiaal. Die E. camaldulensis opstand is gevergelyk met ‘n gemengde opstand van bladwisselende spesies waar daar gevind is dat die fynwortel biomassa in die oppervlak grond onder die E. camaldulensis ongeveer drie keer soveel was as die van onder die gemengde opstand. Kompetisie met aangrensende gewasse is aangeui deurdat die fynwortel biomassa van E. camaldulensis binne die opstand en 10 meter weg van die opstand vergelykbaar was in die oppervlakgronde. Dit dui dus aan dat die plant van E. camaldulensis in assosiasie of aangrensend aan gewasse vermy moet word. Die teenwoordigheid van voedingstowwe en koolstof in die grond van die gemengde opstand was oor die algemeen hoër as die van die E. camaldulensis. Dit is ‘n aanduiding dat die bome van die gemengde opstand meer voedingstowwe aan die grond verskaf.
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Perks, Michael Philip. "Aspects of the water relations of Scots Pine during drought." Thesis, University of Edinburgh, 1998. http://hdl.handle.net/1842/15631.
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This study investigated the physiological response to drought of a 41-year-old Pinus sylvestris stand in south central Scotland. The imposed drought (April-August) resulted in an approximate 15% reduction in the number of functional conduits but no adverse effects on the above ground hydraulic resistance were evident. This may be the result of 'spare capacity' in the amount of conducting tissue or may be indicative of refilling. Under water-stress a significant increase in xylem embolism was detected in 1-year-old shoots. Leaf-level conductance measurements established a strong reduction in conductance with increasing vapour pressure at the leaf surface and a reduction in transpiration and assimilation. Maximal levels of stomatal conductance, under ambient conditions, were 280 mmol m-2 s-1 in water-stressed trees and 315 mmol m-2 s-1 in control trees. Maximum net photosynthesis rates were approximately 4.5 μmol m-2 s-1 in both treatments. Stomatal control of transpiration prevented needle water potential from declining below -1.5 MPa. Strong restrictions on midday conductance at both the leaf and stand levels were apparent when soil volumetric water content declined below a threshold of 12%. The results show an immediate response of leaf conductance to the onset of drought and suggest a mechanism involving sensing of soil water status. There was an increase in ABA in the xylem sap to 600 μmol ml-1 at the height of the drought, but the observed stomatal closure preceded any increase in ABAxyl. Calculations of ABA delivery times suggest it may take a chemical signal in excess of six weeks to travel from root to shoot, in a mature conifer, at the peak of the prolonged water-stress. It is therefore suggested that ABA signals from the roots are not the primary cause of stomatal closure in conifers.
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Ellis, Michael Battiscombe. "Homeostasis : humidity and water relations in honeybee colonies (Apis mellifera)." Diss., University of Pretoria, 2008. http://hdl.handle.net/2263/28357.
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One of the benefits of colonial living in insect societies is the ability to build a nest which enables the maintenance of a homeostatic microenvironment. The detrimental and uncertain effects of fluctuating ambient conditions are thus avoided. An extensive amount of work has documented the regulation of respiratory gases and temperature by honeybee (Apis mellifera) colonies but relatively little is known of their water relations. Nest humidity influences the fitness of the honeybee colony by affecting adult and brood mortality, microbial and parasitic growth, nectar concentration and thermoregulation. This study aims at determining whether honeybee colonies are able to actively regulate humidity within their nest or whether humidity is stabilised merely as consequence of other socially regulated parameters. As a first step in understanding water relations in a hive, the daily, seasonal and two-dimensional humidity patterns are described in diverse contexts: various subspecies, nest architectures, ambient climates and colony conditions. The humidity in the brood nest of a healthy honeybee colony does not show a daily pattern: mean hourly RH remains between 50 and 60 % and high vapour pressure deficit results in a large evaporative capacity. Two-dimensional humidity patterns show that a vapour pressure gradient exists from the central brood area to the periphery of a hive. This finding suggests possible active regulation by workers and to test this idea we determined the behavioural response of a group of workers to a humidity gradient. Young honeybee workers in the absence of brood exhibit a weak hygropreference for approximately 75% RH. When brood is present the expression of this preference is further weakened, suggesting that workers tend to the brood by distributing evenly in the gradient. In addition, fanning behaviour is shown to be triggered by increasing humidity adding to our understanding of this behaviour. Although these results suggest that humidity in honeybee colonies is actively controlled by workers, passive mechanisms are also involved in the observed patterns. Cocoons that are spun by the larvae accumulate in cells and these hygroscopic cocoons contribute to passive stabilisation of humidity. Old comb containing cocoons absorb 11 % of its own mass in water when placed in high humidity and this water can readily evaporate into the atmosphere when humidity decreases. This buffering effect may increase brood survivorship by maintaining a high and stable humidity in the brood cells. This study contributes to our understanding of the complex mechanisms that govern microclimatic regulation in social insect nests and specifically the active and passive mechanisms that ensure homeostasis of honeybee nest humidity. CopyrightDissertation (MSc)--University of Pretoria, 2009.
Zoology and Entomology
unrestricted
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Ellis, Michael B. "Homeostasis : humidity and water relations in honeybee colonies (Apis mellifera)." Pretoria : [s.n.], 2008. http://upetd.up.ac.za/thesis/available/etd-10022009-135223/.
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Naiola, Beth Paul. "Water relations of acacia with special emphasis on osmotic adjustment /." Title page, table of contents and summary only, 1996. http://web4.library.adelaide.edu.au/theses/09PH/09phn1572.pdf.
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Kooy, Michelle Élan. "Relations of power, networks of water : governing urban waters, spaces, and populations in (post)colonial Jakarta." Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/867.
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This thesis documents the genealogy of the development of Jakarta’s urban water supply infrastructure from 1873 (the inception of the first colonial water supply network) to the present. Using an analytical framework of governmentality, supplemented by insights from postcolonial studies and political ecology, the thesis explains the highly unequal patterns of water access in Jakarta as the product of (post)colonial governmentalities, whose relations of power are expressed not only through discursive categories and socio-economic relations, but also through material infrastructures and urban spaces.
The thesis presents material from the colonial archives, Jakarta’s municipal archives, and the publications of international development agencies and engineering consultancy firms. This is combined with primary data derived from interviews, questionnaires, and participant observation of the implementation of current pro-poor water supply projects in Jakarta. This data is used to document how water supply is implicated in the discursive and material production of the city and its citizens, and to challenge conventional developmentalist and academic analyses of water supply access.
Specifically, a conceptual triad of water, space, and populations – produced through, but also productive of government rationalities – is used to explain two apparent paradoxes: (1) the fragmentation of access in Jakarta despite a century of concerted attempts to develop a centralized system; and (2) the preferences of lower-income households for non-networked water supply, despite its higher cost per unit volume. This analysis hinges on an elucidation of the relationships between urban governance and urban infrastructure, which documents the interrelated process of differentiation of types of water supply, water use practices, populations, and urban spaces from the colonial period to the present. This, in turn, is used to explain the barriers being encountered in current pro-poor water supply development projects in Jakarta.
The thesis thus makes a contribution to current academic debates over the ‘colonial present’. The contribution is both theoretical – in the emphasis placed upon the materiality of governmentality – and empirical. Finally, the thesis also makes a contribution to the urban and development studies literatures through its reinterpretation of the urban ‘water crisis’.
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Malusa, James Rudolph. "The phylogeny and water relations of pinyon pines in relation to the vicariance biogeography of the American southwest." Diss., The University of Arizona, 1989. http://hdl.handle.net/10150/191149.
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Axelrod (1958) suggested that the late Tertiary shift in regional climate -- the elimination of summer rains -- had a profound influence on the evolution of biotic provinces in the American southwest. In particular, the taxa endemic to biotic provinces characterized by summer drought, e.g., the Mojave Desert, should be derived from ancestors that likely inhabited regions of summer rain, e.g., the Chihuahuan Desert. Further, the derived features of summer-drought taxa should be related to water stress. I examined Axelrod's thesis, using a combination of phylogenetic systematics, physiological ecology, and vicariance biogeography. The first chapter is a cladistic study of the pinyon pines, 13 taxa of small trees that range from the summer-wet regions of Mexico to the summer drought regions of Nevada and California. A parsimony analysis using twenty morphological characters showed that the most recently derived pinyons are from regions of summer drought. The "summer-drought" taxa are characterized by relatively few needles per fascicle. Because fewer needles per fascicle results in a reduction in the needle surface-to-volume ratio, Haller (1965) hypothesized that fewer needles in pines is an adaptation to reduce transpirational water loss. The second chapter reports on a two year study of the xylem pressure potentials of single- and double-needled fascicles of hybrid pinyons in central Arizona. The results showed no significant differences between single- and double-needles. I concluded that either needle morphology does not effect water relations, or that the relatively high precipitation during the study did not allow significant water stress to occur. The third chapter uses the methods of vicariance biogeography to search for a common pattern of relationship between southwestern biotic provinces, as indicated by the relationships of their endemic taxa. Using a biogeographic parsimony analysis, I compared the area cladograms of six taxa -- junipers, pinyon pines, the composite Palafoxia, hedgehog cactus, desert tortoises, and gecko lizards. The most parsimonious area cladogram supports Axelrod's (1958) hypothesis, but also shows that some taxa, notably the junipers, support other patterns of area relationships, e.g., summer-drought primitive. I suggest that there is no single pattern of area relationships because of the effects of the Pleistocene (including dispersal and extinction) and vicariance events other than the Tertiary climatic change, e.g., the separation of the Baja peninsula from mainland Mexico during the Miocene.
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Hayat, Faisal [Verfasser], and Andrea [Akademischer Betreuer] Carminati. "Impact of heterogeneous soil water distribution on soil and plant water relations / Faisal Hayat ; Betreuer: Andrea Carminati." Bayreuth : Universität Bayreuth, 2021. http://d-nb.info/1227444591/34.
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Gundogdu, Bora. "Relations Between Pore Water Pressure, Stability And Movements In Reactivated Landslides." Master's thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12612967/index.pdf.
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Slope movements cause considerable damage to life and property in Turkey as well as in the world. Although they do not typically cause loss of life, slow landslide movements can severely damage structures, interrupt the serviceability of lifelinesand, related stabilization efforts can be too costly. Most of these slow-moving landslides are reactivated landslides in stiff clays and shales, and they are mainly triggered by rainfall induced high pore water pressures. In this study, a number of reactivated, slow-moving landslide case histories with extensive pore pressure and movement data are selected for further analysis. For these landslides, the relation between pore water pressures, factor of safety and rate of movements of the slide are investigated by using limit equilibrium and finite element methods. It is found that there is a nonlinear relationship between these three variables. Sensitivity of slow moving landslides to changes in pore water pressure is developed by defining the percent change in factor of safety and percent change in pore pressure coefficient, for 10-fold change in velocity. Such relations could especially be useful in planning required level of remediation, for example, to decide on how many meters the ground water level should be lowered at a certain piezometric location, so that the stability increases to a desired level of F.S., and movement rates are reduced to an acceptable slow rate.
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Whittington, John. "Water relations of the mistletoe Amyema miquelii and host Eucalyptus fasciculosa /." Title page, summary and table of contents only, 1985. http://web4.library.adelaide.edu.au/theses/09S.B/09s.bw626.pdf.
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Santos, Miranda Tatiana dos [Verfasser], and Wilfried [Akademischer Betreuer] Konrad. "Water Relations of Lianas / Tatiana Dos Santos Miranda ; Betreuer: Wilfried Konrad." Tübingen : Universitätsbibliothek Tübingen, 2013. http://d-nb.info/1162897058/34.
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Dunsiger, Zoe. "The influence of arbuscular mycorrhiza on the water relations of trees." Thesis, University of Edinburgh, 2001. http://hdl.handle.net/1842/12184.
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This study increases the body of knowledge on the drought response of plant-fungal associations. Hybrid black popular Populus x canadensis, a species commonly seen in shelter belts and small plantations, is tested on its drought response to mycorrhizal colonisation. It also suggests an alternative mechanism for the alteration of plant water relations by arbuscular mycorrhiza. The concept of chemical signalling compounds which control plant response to stress, including drought stress, is topical. This study aims to extend the concept of the plant-fungus symbiosis. The ability of the fungal hyphae to act as an integral part of the root system is tested in its contribution to signalling of drought stress to the host shoot. The response of mycorrhizal poplar to gradients in water availability was tested in two ways. First the effect of changing water availability over time, as drying and wetting cycles, was examined. Second, gradients in water availability across the root-fungal system were considered. The response of poplar to drought stress was tested when inoculated with one of four species of mycorrhizal fungi. These were Glomus intraradices, Glomus mosseae, Gigaspora rosea and Gigaspora margarita. There was no consistent improvement in plant response to drying. However there were variations in plant response over time, and with severity of drought conditions, particularly by plants colonised with G. intraradices and Gi. rosea. Changes in the host plant nutrient status were also found. The concept of hyphal to plant shoot signalling of drought was tested with poplar inoculated with G. intraradices, grown in a specially designed microcosm. Fungal hyphae were able to grow into a separate volume of soil from which plant roots were excluded. The soil water availability around plant roots and adjacent hyphae was altered independently. The plant response in terms of gas exchange was monitored under conditions of varying water availability in each section of the root-hyphal system. In general there were no consistent alterations in plant gas exchange with changing water availability. However during one experiment possible evidence for short-term hyphal signalling to host plants was noticed. This method is suggested as a new concept for further experimentation in plant-fungal water relations.
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Irvine, James. "Water relations of a pine plantation (Pinus sylvestris L.) during drought." Thesis, University of Edinburgh, 1998. http://hdl.handle.net/1842/14153.
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An investigation of the impact of imposed drought on the physiology of 41 year old Scots pine (Pinus sylvestris) was made in southern Scotland. Measurements were made of the seasonal course of transpiration, canopy stomatal conductance, needle water potential, xylem water content, soil-to-needle hydraulic resistance, and growth. Two new techniques were developed to aid these measurements; (i) the use of time domain reflectometry with short probes to detect changes in xylem embolism, and (ii) the continuous measurement of bole water potential based on relating the elastic deformation of the xylem to the internal water tension. Comparison was made between droughted plots and those receiving average precipitation. Under drought, transpiration rate declined once a threshold soil moisture of 12 % volumetric moisture content (VMC) over the top of 20 cm of soil had been reached, and transpiration was thereafter a near linear function of soil moisture. As the drought became intense, hydraulic resistance between soil and needles increased by a factor of three as pre-dawn needle water potential declined from -0.54 MPa to -0.71 MPa. A small but significant increase in xylem embolism was detected in year-old shoots. Stomatal control of transpiration prevented needle water potential from declining below -1.5 MPa. Basal area, shoot and needle growth was significantly reduced in the droughted treatment. In the year following the drought, canopy stomatal conductance and soil-to-needle hydraulic resistance recovered. Current year needle extension recovered, but a significant reduction in basal area increment was evident. Multiplicative non-linear regression models for relating the canopy stomatal conductance to environmental variables were developed. It was found that a simple model that included the effects of air vapour pressure deficit and soil moisture deficit could explain 56 % of the measured canopy stomatal conductance. Overall results suggest that in response to soil drought mature Scots pine closes its stomata sufficiently to prevent the development of substantial xylem embolism. The reduced basal area growth in the year after the drought is not likely to be a result of residual embolism from the previously droughted period.
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Feeney, Deborah Siobhan. "The influence of fungi upon soil structure and soil water relations." Thesis, Abertay University, 2004. https://rke.abertay.ac.uk/en/studentTheses/2a92d2fc-b3c5-456f-8b9a-e406bd78ee84.
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The investigation of soil structural stability and soil water processes was assessed through the application of laboratory investigations and a field based analysis. The impact of an arbuscular mycorrhizal (AM) fungal exudate glomalin (a glycoprotein), proposed to be hydrophobic was assessed for a correlation with low levels of soil hydrophobicity through measures of subcritical water repellency. Initially no correlation was reported but a further temporal investigation that involved a soil inoculum detected a significant positive effect; the results indicated that a certain concentration of protein is required before an influence upon soil hydrophobicity is detected. The temporal investigation detected significant re-aggregation of previously disturbed soil; this was linked to both increases in fungal biomass and enmeshment by plant roots. Soil in the direct vicinity of plant roots showed the most significant increases in aggregated structures, indicating that plant root enmeshment was one of the predominant factors in soil aggregation. Soil water repellency was directly correlated with measures of macroaggregates (aggregates >2000 pm), indicating that increased hydrophobicity is a mechanism involved in aggregate stabilisation. Field scale sampling and analysis indicated that fertilizer applications had varied effects upon fungal populations, dependent on the particular land management applied to the soil. Undisturbed grassland where fungal biomass was likely to be the predominant microorganism present showed significant effects of fertilizer regime upon fungal biomass, with effects likely to be related to plant-fungi interactions through changes in AM fungal biomass. The influence of fertilizer regime on arable sites was less pronounced which indicated a significant influence of disturbance reducing fungal biomass and reducing the direct and indirect effects associated with fertilizer additions. The investigation of soil pore spatial distribution is essential for understanding soil processes as water flow, gas and nutrient exchanges will occur within pore space, as will many biological processes. The investigation of inter-aggregate pore space was completed upon soil aggregates < 2 mm that had been exposed to previous experimental perturbations, where increased aggregate stability, water repellency and fungal biomass were reported. A resolution of «4 pm was achieved and changes in percentage porosity and spatial pore distributions were detected as a result of direct and indirect effects of plant roots. Greatest increases in heterogeneity of pore space were reported in soil from close proximity to roots, with a reduction in this phenomenon at an increasing distance from the root zone. The mechanism proposed for these changes was localised drying from roots. The results presented provide greater understanding of controlling factors associated with soil water and stability mechanisms, along with demonstrating biologically and physically induced changes in micro and meso-scale structures as a result of different treatments. The work provides scope for further investigation of particular biological and physical factors associated with soil structural mechanisms.
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Bergh, Nicola G. "Comparative water relations of indigenous and invasive Australian Proteaceae in fynbos." Bachelor's thesis, University of Cape Town, 1998. http://hdl.handle.net/11427/26049.
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Water-use efficiency (WUE) as reflected in the leaf carbon stable isotope ratio was compared between co-occurring indigenous fynbos proteoids and invasive Australian hakeas H. sericea, H. gibbosa and H. suaveolens. At the driest site, H. suaveolens was slightly more WUE than several co-occurring proteoids; there was no significant difference between hakeas and proteas at the other sites. Transpiration rates of shoots and of whole trees were compared between Hakea sericea and Protea repens growing on Stellenboschberg northeast of Cape Town. Both measurements showed no real difference between the species and it is concluded that differences in water relations are not responsible for the highly competitive growth rates of hakeas in fynbos. It is hypothesised that hakeas may be able to vegetatively outcompete proteoids as a consequence of monopodial architecture and some ability to prevent shade-limitation of photosynthesis. A rough estimate of water loss due to transpiration and interception by H. sericea stands indicates that this species may have a significant effect on catchment water loss relative to open-canopy proteoid fynbos. This effect would be due not to transpiration rates of individual trees but to consistently high densities of mature hakea stands.
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Weeks, Jon Randall 1949. "The growth and water relations of a coastal halophyte, Salicornia bigelovii." Diss., The University of Arizona, 1986. http://hdl.handle.net/10150/191114.
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The succulent, annual euhalophyte, Salicornia bigelovii was grown in 1, 10, 35, 45 and 60 ppt Instant Ocean. This range represents approximately 1/35 to nearly twice the salinity of seawater. The plants in the 4 highest salinities had common final dry weights and seed yields of about 60 and 11 g, respectively, while the 1 ppt plants had 28 and nearly 5 g, respectively. The water relations data reflected the growth and seed production of the plants. The plants in the 4 higher salinities had water potentials sufficient to generate large import gradients and osmotic potentials which contributed to substantial turgors. The 1 ppt plants had a gradient like the rest, but a very low turgor of 0.11 MPa which was barely 23% of that of the lowest of the other treatments. Higher salinities resulted in slightly greater organic and inorganic osmotica contents. Overall, these results suggest a relatively fixed genetic response to a wide range of salinities, as well as an inability to function well at very low salinities. No plant grown at 0 ppt was ever able to reproduce. Therefore, this plant is an obligate halophyte. Experiments in the plant's native coastal estuary indicated meristem water potentials fluctuate with the tides, although they remain about 1.5 MPa below the corresponding soil water potentials. The plants occupy a discrete elevational range throughout the estuary, spending about 1/3 of their daylight hours submerged, and apparently never see dryness. Phenotype differences in the estuary suggest that, within the habitat, pacing and consequent resource domination may be important parameters affecting plant size and possibly fitness. Nitrogen, which is characteristically rare in this and other estuaries, may be critical in this regard. The plants produce large quantities of glycine-betaine, which may be for simultaneous osmoticum use and nitrogen storage. Most roots occur in the first 3 inches of soil. A mechanism is proposed, based on highly efficient compartmentation at the cellular level and the shuttling of organic osmoticum across the tonoplast, by which the tidally based cyclical water potentials could be explained.
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Sickles, Mark David. "The future of intergovernmental relations and the US Army Corps of Engineers changing traditions and building new partnerships." Thesis, Georgia Institute of Technology, 1986. http://hdl.handle.net/1853/29438.
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Avelar, Portillo Lourdes Johanna. "In every cantaro of water| Women's water access struggles in rural El Salvador." Thesis, California State University, Long Beach, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=1598620.
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Latin America is one of the richest regions in the world in rainfall and freshwater resources. Despite this, large populations in this region struggle to gain safe access to safe drinking water supply and sanitation services. The objectives of this research are not simply to show that more wells and better infrastructure are needed. Instead this study encompasses both the physical and emotional geographies of water to dig deep into the social relations to show whether gender intersects with inequalities in water access, and understand how this relationship may cause water insecurities and water distress. By examining local water access in rural El Salvador, my analysis concludes that in every cántaro of water are women’s personal water access struggles. Although some men help with the water collection and carrying labor in rural areas, it is women who as homemakers are more involved and affected by water insecurities.
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Ernstsen, Jerriann. "Effects of Water Stress Preconditioning on Plant Water Relations and Transplant Survival of Artemisia cana and Agropyron intermedium." DigitalCommons@USU, 1993. https://digitalcommons.usu.edu/etd/6513.
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Typically, dormant seedlings are transplanted when revegetating nonirrigated disturbed lands in order to prevent transplant shock triggered by water stress. Since dormant seedlings have to be used, this limits the duration of the transplant season. It may be possible to increase this limited season by inducing acclimation responses that would increase drought tolerance. Preconditioning actively growing seedlings to water stress prior to transplanting could induce acclimation responses such as solute accumulation and/or stomatal modulation.
Under greenhouse conditions, A. cana and A. intermedium seedlings were subjected to three water stress preconditioning treatments: a well watered control, one dry-down cycle, and three dry-down cycles. After conditioning, seedlings were either allowed to dry-down in their containers until leaf senescence, or were transplanted to disturbed land sites. Plant water potential components, relative water content, and leaf mortality were measured.
Immediately following treatments, water relations parameters of preconditioned seedlings were not markedly different from controls in either species. At the end of the final dry-down, water stress preconditioning had not induced active or passive solute accumulation, prolonged leaf survival when exposed to lethal drought conditions, or resulted in differences in transplant survival rates under the experimental conditions of this study.
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Bybee, Megan Claire. "Water governance & international cooperation over trans-boundary water courses in Southern Africa: the case of the Okavango River Basin." Master's thesis, University of Cape Town, 2015. http://hdl.handle.net/11427/17420.
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Includes bibliographical referencesThis dissertation seeks to explore the core drivers of international cooperation over shared water courses particularly in Southern African, using the example of the Okavango River Basin as a case study. As a starting point it highlights the hydro-political context of Southern African, which is dominated by more than 21 shared water courses and faces significant challenges to its water sector namely through climate variability and population growth. In light of these pressing issues which could create a security complex for sovereign riparian states, international cooperation over trans-boundary water sources is imperative. Drawing on core theories of international relations, this dissertation suggests that cooperation between riparian states is a result of strong institutional frameworks, at a river-basin, regional and international level. Cooperation is further reinforced through development functionalism which plays an important role in facilitating cooperation through the advancement of regional development goals and initiatives. Finally, the dissertation explores the role of international norms of cooperation over trans-boundary water courses and the important role they play in fostering cooperation. Using the case of the Okavango River Basin, the dissertation suggests that in Southern Africa, the strongest driver of cooperation is strong legal and institutional frameworks, which once established, form the basis for sustainable cooperation for water diplomacy between riparian states. Cooperation over the Okavango River Basin and the twenty years of cooperation established between Angola, Namibia and Botswana through the Permanent Cubango-Okavango River Basin Commission (OKACOM) highlights an optimistic account for hydro-political cooperation over trans-boundary water systems between sovereign riparian states and provides a useful model for water basin agreements that are yet to be established. This thesis thus concludes that in light of the growing challenges facing the water sector in Southern Africa, strong institutions and legal frameworks are required to enhance cooperation among riparian states.
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Herzog, Karl Martin. "Water relations of a mature subalpine Norway spruce (Picea abies (L.) Karst.) /." [S.l.] : [s.n.], 1995. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=11126.
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Reiner, Susann. "Impact of ozone on the water relations of ash (Fraxinus excelsior L.)." Thesis, University of Nottingham, 1996. http://eprints.nottingham.ac.uk/11434/.
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During the field seasons 1993 and 1994, five-year-old field-grown ash trees as well as potted two-year-old saplings and one-year-old seedlings of ash (Fraxinu. g exccl. 5ior L. ) were exposed to ozone episodes in open-top chambers. The plants received either charcoal-filtered air (CF) or charcoal-filtered air to which 150 ppb of ozone were added (CF+03). Plants in unchambered plots, receiving ambient air (Ambient), were included into the investigation for comparison. Half of the two-year-old saplings of each of the three pollution treatments were subjected to three drought cycles of 7-14 days, while the rest of the plants were well watered as a control. The two-year-old saplings were the main object of the investigation. On these, the main parameters investigated were: stomatal conductance; the growth parameters - extension growth, radial increment at the stembase and radial increment at the base of the new shoot; leaf area; aboveground biomass production; the microscopic determination of ringwidth; and the structure of the latest annual ring for samples taken from the stembase. Additionally, stomatal conductance was measured in the five-year-old trees and total biomass accumulation, photosynthate allocation and ring parameters of the latest annual ring were investigated in the one-year-old seedlings. The ozone episodes were shown to influence stomatal conductance in plants of different water status differently. Drought stress led to a significant decrease of stomatal conductances, and the drought-ozone interaction caused a further decrease which was also significant. The ozone episodes also affected stomatal responsiveness of the plants, restricting stomatal aperture of the droughted two-year-old saplings, when the drought cycles were finished and the plants were maintained at high soil moisture again. The drought cycles alone, however, left the functioning of the stomata unimpaired. The restriction of stomatal aperture which was found for the droughted CF+03 treatment caused reductions of growth and biomass accumulation, but a significant decrease was found only for radial growth at the stembase of those plants. Analysis of the annual rings showed that this was caused by a reduction of xylem growth, while phloem development did not seem to be affected. Radial increment at the base of the new shoot was less affected by the pollution treatment. Here only a significant impact of the drought could be found, and the growth reduction was less pronounced. In the well-watered plants, ozone caused a slight increase in stomatal conductance which led to increased aboveground biomass accumulation, but concomitantly biomass allocation was slightly altered, favouring the crown rather than the lower plant organs. A reduction of photosynthate allocation to the roots became evident from measurements on the one-year-old saplings. Due to chamber effects, stomatal conductance as well as growth, biomass accumulation and allocation differed from those of plants from the Ambient treatment. The responses to ozone that were found in this study could lead to increased crown growth during periods of good water availability and to a strong reduction of water uptake during and following drought conditions. Thus crown demand for water may increase in ash trees exposed to elevated ozone concentrations, while the supply of water to the crown may become limiting.
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Robinson, A. W. "Water relations and the control of flush growth in Theobroma cacao L." Thesis, University of Liverpool, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.380125.
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Bellett-Travers, David Marcus. "Water relations and soil moisture requirements of transplanted amenity trees during establishment." Thesis, University of Hertfordshire, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.251544.
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Beecher, Tim. "Studies on the water relations of the common cultivated mushroom (Agaricus bisporus)." Thesis, Cranfield University, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.341085.
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Eltayef, Khalifa Mohamed Khalifa. "Water and solute relations of salt stressed wheat and annual Suaeda maritima." Thesis, Bangor University, 2014. https://research.bangor.ac.uk/portal/en/theses/water-and-solute-relations-of-salt-stressed-wheat-and-annual-suaeda-maritima(d47951b5-6ff5-4f29-b21e-7c961247169c).html.
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World agriculture is challenged by the increasing demand on diminishing resources of fresh water. Climate change and salinity are both issues, resulting in a major international research effort to breed more resistant crops. The aim of this thesis is to contribute to this effort by determining how wheat varieties respond to salt stress. This study describes an analysis of three wheat varieties (Gamina and Bohoth 105, from Libya and of reported salt tolerance, and Hereward) representing different palis of a salt tolerance spectrum. The effect of induced salt stress on leaf growth rate and final length was investigated by analysing water and solute relations at single cell resolution, using Single Cell Sampling and Analysis (SiCSA). The parameters for the wheat were compared with those of the halophyte (salt tolerant plant) Sea Blight (Suaeda maritima), in order to determine which wheat variety showed the most similar response. All four plants showed rapid cell osmotic adjustment (leaf and root) under salt stress, and leaf turgor pressure was at control levels by 48 hours after salt stress in all wheat varieties. However, varietal differences were evident in terms of cation activity, cortical cell osmotic adjustment, and root turgor regulation, with Bohoth 105 most resembling Suaeda in each. An unexpected observation for wheat leaf cells was a continued increase in turgor pressure after control values had been reached at 48 h post stress, which was not accompanied by an increase in osmotic pressure.
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Caspari, Horst. "The effect of water deficits on the water balance and water relations of Asian pear trees (Pyrus serotina Rehd., cv. Hosui) growing in lysimeters /." Bonn : [s.n.], 1993. http://bibpurl.oclc.org/web/30018.
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Anand, Prathivadi B. "Water and Identity: An analysis of the Cauvery River water dispute." Bradford Centre for International Development, 2004. http://hdl.handle.net/10454/2893.
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YesThis paper focuses on the dispute over river Cauvery in Southern India. Among the causes of river water disputes are contested property rights, difficulty in enforcing such rights, conflict of uses and a lack of willingness to compromise. A co-operative outcome in such cases depends on several factors: asymmetry of power in a triadic relationship between a federal government and two riparian states (one upstream and one downstream). Other factors influencing co-operation are the extent to which the claims of river waters can be elevated from those of immediate riparian peoples to those of an entire state; the dominance of a masculine paradigm towards 'taming' river waters using 'hard' investments rather than 'soft' and decentralised alternatives. On the basis of district level data, the importance of river Cauvery to the hydrology, economy and polity of the two contesting states is examined. This analysis helps us to appreciate why the two riparian state governments have limited room to manouvre. Drawing from two brief case studies of Murray Darling Basin and recent litigation in the USA, and other international experiences of river water treaties, the paper identifies various implications for the resolution of Cauvery and other river water disputes.