Dissertations / Theses on the topic 'Environmental effects on plants'
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Zavistoski, Rebecca Anne. "Hydrodynamic effects of surface piercing plants." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/38026.
Full textIncludes bibliographical references (leaves 124-125).
by Rebecca Anne Zavistoski.
M.S.
Ncise, Wanga. "Environmental stress effects on the phytochemistry and bioactivity responses of a South African medicinal bulbous plant, Tulbaghia violacea Harvey (Alliaceae)." Thesis, Cape Peninsula University of Technology, 2018. http://hdl.handle.net/20.500.11838/2854.
Full textDeteriorating living and environmental conditions have contributed to the increasing prevalence of diseases in plants and animals. In humans, accumulation of abnormally high levels of free radicals in the tissues has been implicated in many non-communicable diseases, such as diabetes, cancer, arthritis, ischemia, gastritis, obesity and asthma. Worldwide, there is recognition of need to improve plant and animal health. Tulbaghia violacea (Alliaceae) is a medicinal plant that is extensively harvested by traditional healers in the wild for its medicinal uses and if this practice continues, it may result in an unsolicited decline of the species in situ. Therefore, there is a need for cultivation of this species. Plant cultivation in a controlled environment for conservation purposes as well as the enhancement of yield and quality is gaining favour among farmers and consumers. The main aim of this study was to investigate the effects of altering the growing conditions by applying environmental stresses on the plant growth, antifungal and antioxidant activities of T. violacea, with the view of enhancing the future cultivation of this species for pharmaceutical companies, traditional healers and the horticulture industry. This study was divided into two parts, and the first part, which was further sub-divided into two separate preliminary experiments, is presented in chapter three. Simultaneous assessments of the effects of i) varied pH levels (pH 4, pH 6, pH 8) and ii) light intensity on plant growth, antioxidant-content and -capacity of extracts of T. violacea were carried out. The second part of the thesis consisted of a more detailed assessment of the above-mentioned independent variables and interactions thereof on plant growth, and antifungal activity of extracts of T. violacea. Results obtained from the first part of the study, showed that plants exposed to pH 6 showed a marked increase in plant height (from 25-37 cm) after 2 months of treatment although, generally, the variations of the different growth parameters among the pH treatments were not significant (p > 0.05). Antioxidant-contents and -capacity were not significantly different (p > 0.05) when pH treatments were compared. However, a high polyphenol content value (of 3 mg/g) occurred in leaves of plants exposed to pH 8. Overall, comparatively, there was no significant difference (p > 0.05) in antioxidant-content and -capacity when pH treatments. In the light experiment, decreasing light intensity led to the elongation of plant height. A higher mean shoot length of 34.6 cm was obtained under low light compared to normal light (26.5 cm) two months post-treatment. The results obtained in this study indicated that light had a significant affect (p < 0.05) on the vegetative growth of this species. In contrast, normal light intensity yielded higher antioxidant-content and -capacity. The polyphenol and flavanol content were fluctuating between the averages of 5.8 mg/g to 8.5 mg/g. Overall, there was a significant difference (p < 0.05) in the antioxidant-content and -capacity when low and normal light intensity treatments compared. In conclusion, both normal light intensity and at pH 8 induced better antioxidant results. In the second part of the study, chapter four, one-month old T. violacea plantlets were grown under two light intensities (low light and normal light) in a greenhouse and concurrently exposed to varying pH levels: pH 4, pH 6 and pH 8. Plants exposed to normal light received natural sunlight through the roof of the greenhouse, while low light intensity (40% reduction) was achieved using shade nets. Plants were drip irrigated with Nutrifeed fertilizer. Plant growth parameters such as height and fresh and dry weights were determined. Leaf samples were analysed for macro-and micro-nutrients contents. Antifungal tests were carried out on the plant extracts from the various treatments in an antifungal bioassay (minimum inhibitory concentration [MIC]). The experimental data collected were analysed using one and two-way analyses of variance (ANOVA), and Tukey HSD was used to separate the means at p < 0.05 level of significance. Varied effects of different pH levels (4, 6 and 8) and light intensities (low and normal) on plant height, and fresh and dry weights were recorded in the current study. A significant interactive (df, 2; F = 0.001; p < 0.001) effect between pH and light on fresh weight was observed. The results revealed that there was a significant difference (df, 2, 57; F = 12.63; p < 0.001) in dry weights with plants under normal light intensity and pH 4 treatment (8.285 ± 0.802 g) producing the highest dry weight. There was a significant interaction (df, 2; F = 6.4; p < 0.001) between pH and light intensity on plant dry weight. Extracts from plants grown under normal light intensity showed stronger antifungal activity at pH level 4, and MIC values ranged from 0.18 ± 0 to 0.375 ± 0.04 mg/ml at 6h and 1.5 ± 0 to 0.97 ± 0.18 mg/ml at 18h. In conclusion, this study demonstrated the interactive effects of pH and light intensity on the growth of T. violacea. These findings also confirmed that it is possible to enhance the cultivation of T. violacea under greenhouse conditions. Chapter 5 focused on the interactive effects of pH and watering regime on plant growth, nutrient uptake and antifungal activity of T. violacea plant extracts, grown hydroponically. The results showed that there were significant differences (p < 0.05) on plant growth parameters amongst the different watering regimes under normal light intensity. Broadly, two trends occurred in the results: firstly, more macro-nutrients were taken up by plants in the higher frequency watering intervals as opposed to higher tissue micronutrient nutrient values for plants grown under the lower light intensity conditions. The levels of N, P, K, Mg nutrient uptake differed significantly in plants (p < 0.001) among watering interval periods. On the other hand, plants simultaneously exposed to extended watering intervals of 21-day and low light intensity showed more bioactivity of the crude extracts against F. oxysporum in the MIC bioassay. Based on the current results, a combination of shorter watering interval and normal light intensity favoured plant growth and development, while plants grown under low light intensity with longer watering interval showed good bioactivity. Broadly, these results demonstrated that varying pH, light intensity, and watering regime can influence plant growth, secondary metabolite contents and antifungal activity of crude extracts of T. violacea. These findings will contribute to the current body of knowledge around cultivation of indigenous medicinal plants. The study will further benefit the conservation of medicinal plant initiatives, increased income of small-scale farmers and potentially promote indigenous knowledge by increasing the availability of South African medicinal plants.
Dodds, Heather Anne. "An investigation into vanadium contamination of soil and its effects on plants." Master's thesis, University of Cape Town, 1994. http://hdl.handle.net/11427/17002.
Full textThis study constitutes a preliminary assessment of the behaviour of effluent-associated vanadium, and its possible effects on the biotic components of land treatment sites, used for the disposal of liquid industrial wastes from a chemical plant in the eastern Transvaal. A review of the literature showed that although the emission of vanadium into the environment is on the increase, very little information is available regarding its behaviour and impact as an environmental pollutant. This study is therefore important not only in the context of the land treatment operation in question, but clearly in a more universal context as well. The study involved a three-phase approach to the problem. Firstly, vanadium sorption was considered in four soils encountered on the sites in question. Secondly, an investigation was conducted into the potential toxicity of vanadium to relevant plant species. Finally, the potential inhibition of soil biological activity at increasing levels of vanadium was examined, although the results of this experiment were inconclusive.
Memon, Ejaz. "Environmental effects of thermal power plant emissions : a case study /." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0016/MQ55524.pdf.
Full textHobson, Colin Desmond. "Environmental and socio-economic effects associated with the planting of Atriplex nummularia Lindl. (Oldman saltbush) in the Karoo." Thesis, Rhodes University, 1991. http://hdl.handle.net/10962/d1001894.
Full textDavey, Jared. "The effects of invasive alien plants on cultural ecosystem services : tourism and recreation." Master's thesis, University of Cape Town, 2011. http://hdl.handle.net/11427/9238.
Full textWith the continued spread of invasive alien vegetation in South Africa, there is a growing need and recognition in protecting ecosystem service delivery. While most literature on ecosystem services has focussed on provisioning and supporting services, this study looks at the less addressed cultural ecosystem services, specifically focussing on tourism and recreation. This research explores the relationship between tourism and invasive alien vegetation. This was carried out at firstly a national level, utilising primarily quantitative methods to identify, and map alien vegetation overlaps with key tourist sites in South Africa. This was followed by a more in-depth qualitative analysis, at a case study level, focussed on the Stellenbosch municipality, to determine the understanding and perceptions, tourists, landowners, and tourism operators have regarding invasive alien plants. Moderate to high levels of infestation were found overlapping various key tourism destinations across the country. The most heavily impacted provinces include the Western Cape, Eastern Cape, and KwaZulu-Natal. In certain areas, invasion levels at key tourist destinations raise concerns regarding the management of these sites. The findings of this research signify a close link and definite relationship between tourism, and invasive alien vegetation. Looking specifically at tourism as a cultural ecosystem service, and the relationship this service has with invasive alien vegetation, future studies need to recognise the significance of this association, while the broader tourism industry needs to recognise the potential threats invasive alien vegetation poses to their operations. Furthermore, this research identifies the value in combining qualitative, human dimensions, with quantitative data and mapping approaches in ecosystem services research.
Pattison, Zarah. "Effects of invasive alien plants on riparian vegetation and their response to environmental factors." Thesis, University of Stirling, 2016. http://hdl.handle.net/1893/25404.
Full textIven, Mark Edward. "An analysis of the inhibitory effects of linolenic acid upon photosystem II of higher plants." PDXScholar, 1989. https://pdxscholar.library.pdx.edu/open_access_etds/3893.
Full textXu, Zhen. "Environmental toxicity testing of chemicals : application of higher plants as test organism to investigate phytotoxic effects /." Aachen : Shaker, 2004. http://bvbr.bib-bvb.de:8991/F?func=service&doc_library=BVB01&doc_number=012998832&line_number=0001&func_code=DB_RECORDS&service_type=MEDIA.
Full textWheeler, Alan David. "Impacts of grazing systems on Nama Karoo phytodiversity." Thesis, Cape Technikon, 2003. http://hdl.handle.net/20.500.11838/2030.
Full textThe study was carried out on two adjacent farms on the plains of the Nama Karoo near Beaufort West. The impacts of three grazing treatments (a) zero grazing (b) non-selective grazing (c) conventional grazing, on plant diversity and certain vegetation parameters were compared. Unpredictable and variable rainfall and major disturbance events such as droughts drive vegetation change in the Nama Karoo. Major recruitment events are rare and can determine Karoo vegetation composition for many years. The diversity of plant species plays an important role in determining vegetation composition during major recruitment events and following drought or disturbance such as grazing. Grazing can influence the composition, abundance and seed production of Karoo plants and in so doing influence the future abundance of desirable and undesirable forage species. These changes may only become evident over long periods, but small changes in vegetation as a response to grazing treatment can accumulate considerably over time.On the farm Elandsfontein, studies have shown that non-selective grazing leads to a higher plant turnover rate, resulting in more vigorous and productive plants, and improved ecosystem functioning. However there is no evidence of this grazing system promoting or reducing plant diversity. The aim of this study was to test whether the non-selective grazing system promoted or reduced plant diversity compared to no grazing and conventional grazing. The hypothesis was that there were no differences between the grazing treatments in terms of plant diversity or any of the vegetation parameters measured. To evaluate this hypothesis, plant data were collected from the three grazing treatments using the Modified-Whittaker vegetation sampling method. The method was further modified for this study to allow for accurate abundance measurements rather than estimates, and an increased area for recording species richness. Using various diversity indices that incorporate species richness and the proportional abundance of species, plant diversity values for each treatment were obtained. No differences in terms of plant diversity were found between the treatments. A significant difference between treatments was found in the density of plants, particularly in perennial grasses and shrubs. Canopy cover percentage did not differ for individual species or as total cover between the treatments.
Holt, Galen. "Diversity Maintenance In Annual Plants And Stream Communities: The Effects Of Life History And Environmental Structure On Coexistence In A Variable Environment." Diss., The University of Arizona, 2014. http://hdl.handle.net/10150/338703.
Full textCreech, Cody F. "Effects of Planting Date, Harvest Date, and Environmental Conditions on Germination of Forage Kochia Accessions." DigitalCommons@USU, 2012. https://digitalcommons.usu.edu/etd/1264.
Full textXu, Zhen [Verfasser]. "Environmental Toxicity Testing of Chemicals: Application of Higher Plants as Test Organism to Investigate Phytotoxic Effects / Zhen Xu." Aachen : Shaker, 2004. http://d-nb.info/1181604419/34.
Full textPrill, Nadine. "Effects of environmental change on plant performance and plant-herbivore interactions." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:c58761e9-666c-4b7d-a78a-d70de7f253d4.
Full textHunt, Matthew. "Effects of environmental change on endophyte-plant-insect relationships." Thesis, University of Oxford, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.275301.
Full textAttwood, Paul Anthony. "Tolerance and growth of willow (Salix viminalis) and willow mycorrhiza in oxygen deficient environments." Thesis, University of Bristol, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.335616.
Full textAl-Salhi, Raghad Adnan Ahmed. "Identification of the xenometabolome and novel contaminant markers in fish exposed to a wastewater treatment works effluent." Thesis, University of Sussex, 2012. http://sro.sussex.ac.uk/id/eprint/40340/.
Full textPeterson, Kenton W. "Environmental effects on turfgrass growth and water use." Diss., Kansas State University, 2013. http://hdl.handle.net/2097/16222.
Full textDepartment of Horticulture, Forestry, and Recreation Resources
Dale J. Bremer
Jack D. Fry
Researchers and practitioners can use numerous techniques to measure or estimate evapotranspiration (ET) from turfgrass but little is known about how they compare to ET using standard lysimeters. An investigation was conducted to compare measurements of ET from lysimeters (LYS[subscript]E[subscript]T) with ET estimates from the FAO56 Penman-Monteith (PM[subscript]E[subscript]T) and Priestley-Taylor (PT[subscript]E[subscript]T) empirical models, atmometers (AT[subscript]E[subscript]T), eddy covariance (EC[subscript]E[subscript]T), and a canopy stomatal conductance model that estimates transpiration (COND[subscript]T). Methods were compared at the same site during the 2010, 2011, and 2012 growing seasons. Overall, PT[subscript]E[subscript]T and EC[subscript]E[subscript]T were not different from LYS[subscript]E[subscript]T, whereas PM[subscript]E[subscript]T, AT[subscript]E[subscript]T, and COND[subscript]T, increasingly underestimated LYS[subscript]E[subscript]T. Differences exist among ET measurement techniques and one should employ the technique that best fits their situation. An atmometer is an inexpensive tool that can be used to measure turfgrass ET within microclimates, such as those typically found in an urban home lawn. An investigation was conducted to compare AT[subscript]E[subscript]T estimates with PM[subscript]E[subscript]T estimates within a number of lawn microclimates. Home lawns in Manhattan and Wichita, KS, were selected for study during the growing seasons of 2010 and 2011. Open sward AT[subscript]E[subscript]T was 4.73 mm d[superscript]-[superscript]1, whereas PM[subscript]E[subscript]T was 5.48 mm d[superscript]-[superscript]1. Within microclimates, AT[subscript]E[subscript]T was 3.94 mm d[superscript]-[superscript]1 and PM[subscript]E[subscript]T 3.23 mm d[superscript]-[superscript]1. Atmometers can provide practitioners with reliable estimates of PM[subscript]E[subscript]T within microclimates. Zoysiagrass (Zoysia spp.) is a common turfgrass used on home lawns and golf courses. However, poor shade tolerance and cold hardiness have limited its use in the transition zone. A study was conducted to determine changes and differences in growth and physiology among selected Zoysia over a three-year period (2010-2012) in the transition zone. The genotypes were 'Emerald' [Z. japonica × Z. pacifica], 'Zorro' [Z. matrella], 'Meyer' and Chinese Common [Z. japonica], and experimental progeny Exp1 [Z. matrella × Z. japonica], and Exp2 and Exp3 [(Z. japonica × Z. pacifica) × Z. japonica]. 'Zorro' and 'Emerald' experienced winter injury. 'Meyer', Chinese Common, and Exp1 showed poor performance over the three-years. The Exp2 and Exp3 progeny, maintained high percent cover, visual quality, and tiller density, and may provide practitioners more shade-tolerant cultivar choices in the transition zone.
Ramachandran, Gurumurthy. "Computerized feedback control of an environmental chamber." Thesis, Virginia Tech, 1988. http://hdl.handle.net/10919/43278.
Full textMaster of Science
LAIBI, SAMI RESHAK. "EFFECT OF ENVIRONMENTAL FACTORS AND APPLIED GROWTH REGULATORS ON GROWTH, CYTOKININ PRODUCTION AND PHYSIOLOGICAL CHANGES OF PEPPERS (CAPSICUM ANNUUM L.) (ARIZONA)." Diss., The University of Arizona, 1985. http://hdl.handle.net/10150/188004.
Full textHowe, Katherine Mitchell. "The ecology of invasions in a Minnesota grassland : characteristics of invasive species and invaded communities and the effects of global change /." Thesis, Connect to this title online; UW restricted, 2002. http://hdl.handle.net/1773/5266.
Full textDavison, Elizabeth L. 1947, and Elizabeth L. 1947 Davison. "Caesalpinia pulcherrima, Calliandra californica, and Justicia specigera: Chemical and environmental regulation of their growth and development." Thesis, The University of Arizona, 1989. http://hdl.handle.net/10150/277127.
Full textMaurer, Kyle D. "The Bias towards Updrafts for Seed Abscission of Wind Dispersing Plants and its Effects on Dispersal Kernels." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1316095873.
Full textSearles, Peter S. "Responses of Sphagnum and Carex Peatlands to Ultraviolet-B Radiation, and a Meta-Analysis of UV-B Effects on Vascular Plants." DigitalCommons@USU, 2000. https://digitalcommons.usu.edu/etd/6578.
Full textJune, Tania. "Environmental effects on photosynthesis of C₃ plants scaling up from electron transport to the canopy (Study case: Glycine max L. Merr) /." Online version, 2002. http://bibpurl.oclc.org/web/23803.
Full textKapira, Elvanus. "EFFECTS OF PLANT HARVESTING ON NUTRIENTS REMOVAL IN CONSTRUCTED WETLANDS." Thesis, Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-35170.
Full textJoubert, Retief. "Influence of geometric and environmental parameters on air-cooled steam condenser performance." Thesis, Stellenbosch : University of Stellenbosch, 2010. http://hdl.handle.net/10019.1/4153.
Full textENGLISH ABSTRACT: Air-cooled steam condensers (ACSCs) are used in the power generation industry to directly condense turbine exhaust steam in areas where cooling water is expensive or unavailable. Large axial flow fans force ambient air through A-frame heat exchanger bundles made up of a number of rows of finned tubes through which the steam is ducted and consequently condensed during the heat transfer process to the air. The heat rejection rate or performance of an ACSC is proportional to the air mass flow rate, determined by fan volumetric performance, and the temperature difference between the finned tubes and the air. The air flow through a 30 fan ACSC (termed the generic ACSC) operating under windy conditions is solved using the commercial computational fluid dynamics (CFD) code FLUENT and the required data is extracted from the solution to calculate performance trends. It is found that fan performance is reduced due to a combination of factors. The first is additional upstream flow losses caused by separated flow occurring primarily at the leading edge of the ACSC and secondarily at the fan bellmouth inlets. The second factor leading to reduced fan performance is the presence of distorted flow conditions at the fan inlets. Hot plume air recirculation is responsible for decreased ACSC thermal performance due to increased fan inlet air temperatures. It is found that reduced fan performance is the greater contributor to reduced ACSC performance. The performance effects of varying two geometrical parameters of the generic ACSC, namely the fan platform height and the windwall height, are investigated under windy conditions. It is found that each parameter is linked to a specific mechanism of performance reduction with the fan platform height affecting fan performance and the windwall height affecting recirculation. The respective platform and windwall heights specified for the generic ACSC are found to provide acceptable performance results. To mitigate wind induced performance reductions a number of modification and additions to the ACSC are investigated. These primarily aim at improving fan performance and included the addition of walkways or skirts, the addition of wind screens beneath the fan platform, removing the bellmouth fan inlets, using different types of fans and increasing fan power. The addition of a periphery walkway and windscreens is considered to be the most practical methods of improving ACSC performance under windy conditions. The generic ACSC is modified to include both modifications and under high wind conditions the performance is found to increase measurably. The modifications also resulted in the ACSC performance being less sensitive to wind direction effects.
AFRIKAANSE OPSOMMING: Lugverkoelde kondensators word in die kragopwekkings industrie gebruik om turbine uitlaatstoom te kondenseer, veral in gebiede waar verkoelingwater duur of onbeskikbaar is. Aksiaalvloei-waaiers forseer omgewingslug deur A-raam warmteuitruiler bondels wat bestaan uit verskeie rye vinbuise. Die uitlaatstoom vloei in die vinbuise en kondenseer as gevolg van die warmteoordrag na die lug. Die warmteoordragkapasiteit van die lugverkoelde stoom kondensator is eweredig aan die massavloei-tempo van die lug, wat bepaal word deur die waaierwerkverigting, en die temperatuur verskil tussen die vinbuise en die lug. Die lugvloei deur 'n 30 waaier lugverkoelde stoom kondensator (genoem die generiese lugverkoelde stoom kondensator) onderworpe aan winderige toestande word opgelos deur die gebruik van die kommersiële vloeidinamika-pakket, FLUENT. Die nodige data is onttrek uit die oplossing en werkverrigting neigings is bereken. Dit is gevind dat waaierwerkverigting verminder as gevolg van 'n kombinasie van faktore. Die eerste is bykomende vloeiverliese wat veroorsaak word deur vloeiwegbreking wat plaasvind primêr by die voorste rand van die lugverkoelde stoom kondensator asook by die klokvormige waaier-inlate. 'n Tweede faktor wat lei tot vermindere waaierwerkverigting is die teenwoordigheid van lugvloeiversteurings by die waaier-inlate. Hersirkulering van warm pluim lug is ook verantwoordelik vir verminderde lugverkoelde stoom kondensator werkverrigting. Daar word bevind dat die vermindering in waaierwerkverrigting die grootste bydraende faktor tot vermindere lugverkoelde stoom kondensator werkverrigting is. Die effek van verandering van twee geometriese lugverkoelde stoom kondensator parameters, naamlik die waaierplatformhoogte en die windwandhoogte is ondersoek onder winderige toestande. Daar word bevind dat elk van die parameters gekoppel is aan 'n spesifieke meganisme van vermindere lugverkoelde stoom kondensator verrigting: Die waaierplatformhoogte beïnvloed waaierverrigting terwyl die windwandhoogte hersirkulering beinvloed. Daar word ook bevind dat die onderskeie waaierplatform- and windwandhoogtes van die generiese lugverkoelde stoom kondensator, van so 'n aard is dat dit aanvaarbare werkverrigting tot gevolg het. Om verlaging in werksverrigting in winderige toestande te verminder is verskeie modifikasies en byvoegings tot die lugverkoelde stoom kondensator ondersoek wat primêr gemik is op verbetering in waaierwerkverigting. Die ondersoek dek die byvoeging van 'n loopvlak, die byvoeging van windskerms onder die waaierplatform, verwydering van die klokvormige waaier-inlate, die gebruik van verskillende waaiers en die verhoging van waaierdrywing. Daar was besluit dat die byvoeging van 'n loopvlak rondom die rand van die lugverkoelde stoom kondensator en die byvoeging van windskerms die mees praktiese manier was om die lugverkoelde stoom kondensator verigting te verbeter. Die generiese lugverkoelde stoom kondensator was aangepas om beide veranderings in te sluit en meetbare verbetering in werkrigting was verkry. Die veranderings het ook meegebring dat die lugverkoelde stoom kondensator minder sensitief is vir windrigting effekte.
Janks, Matthew Richard. "Montane Wetlands of the South African Great Escarpment : plant communities and environmental drivers." Thesis, Rhodes University, 2015. http://hdl.handle.net/10962/d1018917.
Full textTouny, Mahmoud A. "The effects of environmental regulations on industrial plant inefficiency and the determinants of plant environmental performance : a case study of Egypt." Thesis, University of East Anglia, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.410071.
Full textPoteet, D. C., D. L. Robinson, A. K. Dobrenz, and S. E. Smith. "The Effects of Alfalfa Seed Scarification in Saline Environments." College of Agriculture, University of Arizona (Tucson, AZ), 1988. http://hdl.handle.net/10150/200811.
Full textBateman, Mark J. "The uptake of heavy metals by aquatic macrophytes and the development of microsampling analytical techniques." Thesis, Coventry University, 1999. http://curve.coventry.ac.uk/open/items/82ba9974-f8fc-6290-40a7-3a64e63ff8a6/1.
Full textLou, Laiqing. "Arsenic uptake, accumulation and tolerance in Chinese brake fern (Pteris vittata L., an arsenic hyperaccumulator) under the influence of phosphate." HKBU Institutional Repository, 2008. http://repository.hkbu.edu.hk/etd_ra/928.
Full textLynes, Melissa Kate. "Production efficiencies of U.S. electric generation plants: effects of data aggregation and greenhouse gas and renewable energy policy." Diss., Kansas State University, 2015. http://hdl.handle.net/2097/19781.
Full textDepartment of Agricultural Economics
Jeffery R. Williams
Over the last few decades there has been a shift in electricity production in the U.S. Renewable energy sources are becoming more widely used. In addition, electric generation plants that use coal inputs are more heavily regulated than a couple decades ago. This shift in electricity production was brought on by changes in federal policy – a desire for electricity produced in the U.S. which led to policies being adopted that encourage the use of renewable energy. The change in production practices due to policies may have led to changes in the productivity of electric generation plants. Multiple studies have examined the most efficient electric generation plants using the data envelopment analysis (DEA) approach. This study builds on past research to answer three questions: 1) Does the level of aggregation of fuel input variables affect the plant efficiency scores and how does the efficiency of renewable energy input compare to nonrenewable energy inputs; 2) Are policies geared toward directly or indirectly reducing greenhouse gas emissions affecting the production efficiencies of greenhouse gas emitting electric generation plants; and 3) Do renewable energy policies and the use of intermittent energy sources (i.e. wind and solar) affect the productivity growth of electric generation plants. All three analysis, presented in three essays, use U.S. plant level data obtained from the Energy Information Administration to answer these questions. The first two essays use DEA to determine the pure technical, overall technical, and scale efficiencies of electric generation plants. The third essay uses DEA within the Malmquist index to assess the change in productivity over time. Results indicate that the level of aggregation does matter particularly for scale efficiency. This implies that valuable information is likely lost when fuel inputs are aggregated together. Policies directly focused on reducing greenhouse gas emissions may improve the production efficiencies of greenhouse gas emitting electric generation plants. However, renewable energy policies do not have an effect on productivity growth. Renewable energy inputs are found to be as efficient if not more efficient than traditional energy sources.
Larsson, Marie-France. "The Effect of Plants on Individuals' Stress Level in an Indoor Work Environment." Thesis, Mid Sweden University, Department of Social Sciences, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-11141.
Full textMany instances of sick leave can be linked to diseases caused by stress. An efficient way to counter the negative effects of stress is coping. However, trying to fit coping activities into an already busy schedule can be stressful in itself. Therefore it is interesting to study passive stress-reducing methods, for instance interaction with nature. This paper studied the effect of the presence of plants in a work-like environment on the stress level of 30 participants divided equally in a control group and a test group by measuring their heart rate. A factorial analysis of variance and a multivariate analysis of variance were used to analyze the data. Despite the heart rate of the control group being on an average 5 beats per minute higher than the test group, the difference was found not to be statistically significant. An explanation for this could be the poor reliability of heart rate as a measure of stress.
Keywords: coping, heart rate, indoors, nature, plants, stress, work
Larson, Daniel. "Non-indigenous freshwater plants : patterns, processes and risk evaluation /." Uppsala : Dept. of Environmental Assessment, Swedish University of Agricultural Sciences, 2007. http://epsilon.slu.se/200715.pdf.
Full textDolan, Bianca Christine. "Effects of Increased Nitrogen Deposition on the Dominance of Hedera helix in the Pacific Northwest." PDXScholar, 2013. https://pdxscholar.library.pdx.edu/open_access_etds/680.
Full textSequera, Mutiozabal Miren Iranzu. "Polyamine signaling pathway during environmental stress: Metabolomic approaches to elucidate spermine down-stream targets." Doctoral thesis, Universitat de Barcelona, 2015. http://hdl.handle.net/10803/315648.
Full textEl estrés medioambiental está afectando de forma paulatina la productividad de los cultivos. En la búsqueda de soluciones, uno de los principales objetivos de la investigación en fisiología de plantas, es dilucidar los mecanismos de tolerancia que se presentan ante diversos estreses, con la finalidad de generar plantas con fenotipos resistentes. En referencia a este asunto, las poliaminas y sus rutas señalizadoras son de importancia crucial. Las más abundantes en plantas (putrescina, espermidina y espermina) tienden a acumularse en respuesta al estrés por lo cual se les asocia a un rol protector, sin embargo, las tendencias de acumulación dependen del tipo de estrés que la planta es capaz de percibir. De hecho, su ruta biosintética se activa a diferentes niveles dependiendo del estímulo, lo cual les confiere un carácter selectivo. La Espermina (una de las poliaminas superiores) no es esencial para el crecimiento de la planta, no obstante, actualmente se sabe que esta molécula ejerce diversos roles protectores en una gran variedad de condiciones y además activa cascadas señalizadoras implicadas en la respuesta defensiva de la planta. En consecuencia, para dilucidar los mecanismos de tolerancia, se ha hecho necesario profundizar en las dianas de señalización por parte de la espermina. Empleando como modelo experimental Arabidopsis thaliana, el presente estudio ha demostrado la implicación de este policatión en el aumento de la capacidad anti-oxidativa a través de conexiones con metabolitos centrales en el metabolismo de azucares, lípidos y aminoácidos como es el caso del piruvato y el mio-Inositol, así como también, la implicación de esta poliamina en la morfología y ramificación de las raíces, reforzando la noción de implicación esencial por parte de esta poliamina, en la fisiología del estrés en plantas.
Facun, Jasmine B. "Effects of Mowing Regimes on the Plants, Pollinators, and Roughness of the Channelized Hocking River’s Riparian Zone, Athens, Ohio." Ohio University / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1597248243432497.
Full textStruckhoff, Garrett Cletus. "Plant-assisted bioremediation of perchlorate and the effect of plants on redox conditions and biodiversity in low and high organic carbon soil." Diss., University of Iowa, 2009. https://ir.uiowa.edu/etd/441.
Full textScarano, Fabio Rubio. "The effects of ontogeny and environmental oscillations on plant responses to oxygen deprivation." Thesis, University of St Andrews, 1993. http://hdl.handle.net/10023/14344.
Full textJablonski, Leanne M. "Reproductive response to elevated CO2 : the roles of vegetative carbon storage, nitrogen and seed traits." Thesis, McGill University, 1997. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=34646.
Full textReed, Donna K. "Impact zone delineation for biological assessment of power plant effluent effects on snail populations in the Clinch River." Diss., Virginia Tech, 1993. http://hdl.handle.net/10919/38639.
Full textNiziolek, Dani R. "Landscape Effects on Urban Plant Traits: Rethinking the Value of Urban Weeds." Ohio University Honors Tutorial College / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=ouhonors1587738269628448.
Full textSohel, Mohammed Imroz. "Thermodynamic Modelling and Simulation for High Efficiency Design and Operation of Geothermal Power Plants." Thesis, University of Canterbury. Mechanical Engineering, 2011. http://hdl.handle.net/10092/5292.
Full textGenter, Robert B. "Population and community changes of attached-algae to zinc stress alone and in combination with selected environmental variables." Diss., Virginia Polytechnic Institute and State University, 1986. http://hdl.handle.net/10919/49778.
Full textSessoms, Holly Nicol. "Water use potential and salt tolerance of riparian species in saline-sodic environments." Thesis, Montana State University, 2004. http://etd.lib.montana.edu/etd/2004/sessoms/SessomsH0805.pdf.
Full textStegemeier, John Peter. "Effects of Transformations of Ag and CuO Nanoparticles on Their Fate in Freshwater Wetland Sediments and Plants." Research Showcase @ CMU, 2016. http://repository.cmu.edu/dissertations/714.
Full textSezer, Ozcelik Ganime Asli. "Prediction Techniques Of Acid Mine Drainage: A Case Study Of A New Poly- Metallic Mine Development In Erzincan-ilic, Turkey." Phd thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/3/12608263/index.pdf.
Full textÇ
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pler Gold Prospect case. The mineralization in Ç
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pler is in sulfide and oxide types. The oxide is a supergene alteration and porphyry-copper type gold mineralization is classified as an intermediate sulfidation. The major lithologies observed in the study area are the regionally un-correlated meta-sedimentary lithologies, Munzur Limestone, and the Ç
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pler Granitoid.Thirty-eight representative samples were tested for AMD prediction purposes. Sixteen more were included to the sampling scheme for site characterization. Both acid producing and neutralizing lithologies are present in the mine site. Similarly it was revealed that the sulphate sulfur content of the samples were insignificant that any determined total sulfur amount can be directly considered as the factor for AMD production. Geochemical data revealed arsenic enrichments up to 10000 ppm in the study area. Therefore, during the operational stage, in addition to the planning to avoid or minimize AMD, it is necessary to take precautions against arsenic mobilization during the design of the AMD neutralization scheme. Both Kinetic studies and the heavy metal mobilization related to AMD are kept out of the scope of this investigation. Similarly, management and abatement stages of AMD are excluded.
Naidu, Bodapati Purushothama. "Variability in the accumulation of amino acids and glycinebetaine in wheat and barley under environmental stress /." Title page, table of contents and summary only, 1987. http://web4.library.adelaide.edu.au/theses/09PH/09phn155.pdf.
Full textRaeini, Sarjaz Mahmoud. "The influences of environmental diversity on water-use efficiency, carbon isotope discrimination leaf movements and nutrition of bush bean." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape16/PQDD_0028/NQ37014.pdf.
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