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Agyeman, Victor Kwame. "Environmental influences on seedling growth." Thesis, University of Aberdeen, 1994. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU068823.
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The tropical high forests of West Africa have been under stress due to a greater dependence on wood resources. Logging rate has more than doubled within the last decade. However, the exact effects of logging on vegetation composition and the degree of canopy opening that should be created in the forest to ensure the regeneration of timber tree species are not known. Three major experiments were carried out to determine the ecophysiological responses of timber tree species in different irradiances and red:far-red ratios. (1) 16 tree species were grown in six neutral shade treatments (2, 6, 27, 42 and 65% full sun) and their growth assessed by standard measurements used in growth analysis (biomass, height, stem diameter, leaf area, leaf production and mortality). (2) Eight species, of which six were also used in the shade house experiment, were grown in a series of artificially-created gaps in two forest sites differing in annual rainfall. Gaps created received 1-2, 5, 10, 15, 30 and 66% full sun. (3) Possible differences in the results between shade house and forest experiments due to differences in light quality (red:far-red ratio) were tested separately. Differences in red:far-red ratio has little effect of growth but showed some influence on allocation of biomass. Seedling growth response of species were higher in shade houses compared to the two field sites and higher in the wet compared to dry forests. Sixteen tropical timber tree species were ranked on an ecological (shade tolerance) gradient based on their differential growth response to light. The results indicate that the ranking of species on an ecological gradient is robust and potentially more reliable than intuitive classification of species into groups.
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Kilaru, Aruna, and Kent D. Chapman. "N-Acylated Phospholipid Metabolism and Seedling Growth." Digital Commons @ East Tennessee State University, 2012. https://doi.org/10.4161/psb.21314.
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N-Acylphosphatidylethanolamines (NAPEs) are precursors of endogenous bioactive lipids, N-acylethanolamines (NAEs). NAPEs, which occur as a minor membrane lipid, are hydrolyzed in a single enzymatic step catalyzed by a type of phospholipase D (PLD) to generate fatty acid ethanolamides. Although, the occurrence of NAPE is widespread in the plant kingdom, the physiological roles remain under appreciated due to the lack of sensitive tools to quantify the pathway metabolites. In Kilaru et al. (2012, Planta, DOI 10.1007/s00425-012-1669-z), comprehensive mass spectrometry (MS)-based methods were developed to gain a clearer understanding of the complex network of metabolites that participate in NAE metabolic pathway. This targeted lipidomics approach allowed insights to be drawn into the implications of altered NAE levels on NAPE content and composition, and the overall regulation of PLD-mediated hydrolysis in Arabidopsis. Based on these results, we point out here the important need for the identification of the precise isoform(s) of PLD in plants that is (are) involved in the regulated hydrolysis of NAPE and formation of NAE lipid mediators in vivo.
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Bloomberg, Mark. "Modelling germination and early seedling growth of radiata pine." Lincoln University, 2008. http://hdl.handle.net/10182/681.
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Background: This study seeks to model aspects of the regeneration of radiata pine (Pinus radiata D.Don) seedlings under a range of environmental conditions. This study investigated whether “hybrid” mechanistic models, which predict plant growth and development using empirical representations of plant physiological responses to the environment, could provide a realistic alternative to conventional empirical regeneration models. Objectives: The objectives of this study were to 1) identify the functional relationships between the environmental conditions controlling germination, establishment and growth of radiata pine seedlings, under a range of those environmental conditions as specified by temperature and available light and soil water; and 2) specify those functional relationships in hybrid mechanistic (“hybrid”) models. Methods: Radiata pine seedling germination and growth were measured under controlled environmental conditions (incubators for seed germination, growth cabinets for seedlings), and results used to adapt, parameterise and test two published hybrid models; one for germination (the hydrothermal time model); and one for seedling growth in the first six months after germination, based on plant radiation use efficiency (RUE). The hydrothermal model was tested by incubating commercial radiata pine seeds under factorial combinations of temperature and water potentials where germination was likely to occur (12.5 ºC to 32.5 ºC and 0 MPa to –1.2 MPa.). 100 seeds were germinated for each factorial combination. The hydrothermal germination model was fitted to the germination data using non-linear regression modles, will allowed simultaneous estimation of all modle parameters. Seedlings were grown in controlled growth cabinets, and their RUE was calculated as the ratio of net primary production (NPP, specified in terms of an increase in oven dry biomass), to PAR intercepted or absorbed by a seedling. Estimation of seedling RUE required development of novel techniques for non-destructive estimation of seedling oven dry weight, and measurement of PAR interception by seedlings. The effect of varying PAR flux density on RUE was tested by measuring RUE of seedlings grown at 125, 250 and 500 µmol m⁻² s⁻¹. In a second experiment, the effect of deficits in available soil water on RUE was tested by measuring RUE of seedlings grown under 250 µmol m⁻² s⁻¹ PAR flux, and at different levels of available soil water. Available soil water was specified by a soil moisture modifier factor (ƒθ) which ranges between 1 for moist soils and 0 for soils where there is insufficient water for seedling growth. This soil moisture modifier had not previously been applied in studies of tree seedling growth. Temperatures for both seedling experiments were a constant 17.5 ºC (day) and 12.5 ºC (night). Results: Hydrothermal time models accurately described radiata pine seed germination. Model predictions were closely correlated with actual seed germination over the full range of temperature and water potentials where germination was likely to occur (12.5 ºC to 32.5 ºC and 0 MPa to –1.2 MPa. The minimum temperature for germination (base temperature) was 9.0 ºC. Optimum temperatures for germination ranged from ~20ºC for slow-germinating seeds to ~27 ºC for the fastest germinating seeds. The minimum water potential for seed germination varied within the seed population, with an approximately normal distribution (base water potential = –1.38 MPa, standard deviation of 0.48 MPa). In the process of developing the model, a novel explanation for the decline in germination rates at supra-optimal temperatures was developed (Section 3.4.6), based on earlier models proposed by Alvarado & Bradford (2002) and Rowse & Finch-Savage (2003). This explanation was that the decline in germination rate was not driven just by temperature, but by accumulated hydrothermal time above the base temperature for germination (T₀). This in turn raised the base soil water potential (Ψb) towards 0, so that the reduction in germination rate arose from a reduced accumulation of hydro-time, rather than from thermal denaturation of enzymes facilitating germination – the conventional explanation for non-linear accumulation of thermal time at supra-optimal temperatures for plant development. Upwards adjustment (towards 0 MPa) of base water potentials of germinating seeds occurred also at very cold temperatures in combination with high water potentials. In both cases (very cold or else supra-optimal temperatures) this upwards adjustment in base water potentials prevented germination of part of the seed population, and is proposed as a mechanism which enables seed populations to “hedge their bets” when germinating under less than ideal germination conditions. RUE of young germinated radiata pine seedlings growing in a controlled growth cabinet was not significantly different over a range of constant PAR flux densities. Mean RUE’s were 3.22, 2.82 and 2.58 g MJ⁻¹ at 125, 250 and 500 µmol m⁻² s⁻¹ respectively. In the second experiment, the novel use of a soil moisture modifier (ƒθ) to predict RUE of seedlings subjected to water stress proved successful within a limited range of soil water stress conditions. Measured seedling transpiration and stomatal conductance were closely correlated but seedling photosynthesis was less correlated with available soil water. This result suggests that photosynthesis was not coupled with stomatal conductance when PAR flux was 250 µmol m⁻² s⁻¹, which is well below saturating irradiance for C₃ plants. Conclusions: The use of hybrid, quasi-mechanistic models to describe tree seedling growth has been seldom explored, which necessitated the development of novel experimental and analytical techniques for this study. These included a predictive model of germination decline at sub- and supra-optimal temperatures; a method for accurately estimating seedling dry weights under a range of PAR flux densities; and a novel method for estimating light interception by small seedlings. The work reported in this thesis showed that existing hybrid models (the hydrothermal time germination model and the RUE model) can be adapted to model germination and growth of radiata pine seedlings under controlled environmental conditions. Nonetheless, further research is needed before the models can be confidently used as an alternative to conventional empirical models to model regeneration in “real-world” forests. Research priorities are the performance of hydrothermal germination models under variable field conditions, and the use of the soil moisture modifier for seedlings growing on a range of soil textures and under a range of PAR fluxes.
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Taylor, Anne. "Phototropism, traumatropism and blue light effects on seedling growth." Thesis, University of Aberdeen, 1987. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU010196.
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The growth events which are responsible for the phototropic curvature of seedlings towards blue light were investigated by growth analysis of seedlings of Avena sativa L. Time-lapse video analysis of coleoptiles given equivalent unilateral or bilateral blue light stimuli showed that both the duration and fluence-rate of the light treatments affected the growth responses which were recorded. The results suggest that the growth responses in bilateral light occur simultaneously with the growth changes which cause phototropic curvature, although they do not appear to make any contribution to the magnitude of curvature. Seedlings were also subjected to continuous unilateral microbeam (1mm) irradiation of discrete zones, to investigate whether 'message' transmission occurs in phototropism. The growth changes which occur in response to this treatment were recorded over the whole length of a 20 mm seedling, but began at different times in different zones. It was concluded that there must be some kind of 'message' transmission following perception of a phototropic stimulus in Avena. The kinetics of the response showed that it was unlikely that transmission could be simply due to tissue light-piping from the position of the original light beam. Unilateral irradiation of a small zone at the base of a coleoptile resulted in negative curvature. This experiment provided some evidence for acropetal transmission of the phototropic signal. A study was also made on the effects of wounding on the growth of Avena seedlings. This led to a re-evaluation of the significance of the traumatropic response to unilateral wounding. The experiments showed that even a slight wound can have severe effects on the growth of a coleoptile. The results are discussed in relation to previous theories on the mechanism of traumatropic curvature.
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Hahne, Kathryn S., and Ursula K. Schuch. "Nitrogen Requirements of Prosopis Velutina during Early Seedling Growth." College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2004. http://hdl.handle.net/10150/216532.
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The objective of this study was to determine the optimum rate of N to maximize growth of Prosopis velutina seedlings and minimize N leaching when seedlings were grown in different substrates. Mesquite seedlings were grown in sand or soilless media and were fertigated with a solution of67 % NH₄⁺: 33 % NO₃⁻ at a rate of 25, 50, 100, or 200 mg N/L. After 60 days, plants in media produced 41 % more leaves and total biomass compared to those in sand. Leaf number was greatest for plants grown at 200 mg N/L in both substrates. Root biomass of plants in media showed no response to increasing N concentrations while root biomass of seedlings in sand were similar for the three lower N concentrations and nearly doubled for the highest one. Shoot biomass of seedlings receiving 25, 50, or 100 mg N/L was similar, but more than doubled for plants fertigated with 200 mg N/L. N leachate losses were highest from seedlings growing in sand and receiving the two higher N fertigations, those in media had greatest N leachate loss when fertigated at 200 mg N/L.
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Kamboozia, Jafar. "Seedling vigour in winter grain legumes." Title page, table of contents and abstract only, 1994. http://web4.library.adelaide.edu.au/theses/09PH/09phk152.pdf.
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Abreu, F. M. S. G. "Influence of atmospheric saturation deficit on early growth of groundnut." Thesis, University of Nottingham, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.378471.
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Sinclair, John. "Crusting, soil strength and seedling emergence in Botswana." Thesis, University of Aberdeen, 1985. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU363198.
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This thesis gives the results of an investigation of the strengths and particularly the crust forming potential of arable soils from Botswana and the relationship to seedling emergence of sorghum, the most important crop in Botswana and one that because of its small seed weight (about 2 0 mg) can fail to emerge through a hard soil crust. A review of the literature suggested that the soil factors which had to be considered were dispersibility of clay and factors which affect this, and the bulk density of the soils. Soils which are found in many tropical and sub-tropical regions, with low organic matter and inactive clays can set hard after a simple wetting and drying cycle. In these soils, the strength is very strongly dependent on the water content, showing a hyperbolic or exponential relationship-, and the strengths when dry may be very greatly increased by remoulding the wet soil. The crust strength required to prevent seedling emergence varies with the size of the seedling and for cotton (seed weight about 80 mg), 1-3 MPa penetration resistance measured with a penetrometer is sufficient to prevent emergence. Seedlings exert a total force proportional to their number. In the experimental programme, seedlings' forces were measured, seedling emergence observed in a field experiment under crusting conditions, and the strength characteristics of a group of soils, representative of arable soils in Botswana, studied. A sorghum seedling was found to exert a maximum force of about 1 N or dividing by the area of the plumule, a pressure of about 0,5 MPa. The field experiment showed that much better emergence was obtained from planting 15 seeds together than from planting 4 seeds together when a crust formed after planting. A study of 32 soils, most of them sand to sandy loam in texture but with a few clays and hydroirorphic soils, from arable areas in Botswana showed the sandy to sandy loam soils to have high bulk densities ( 1,45-1 ,75 Mg/m3) and extremely low organic carbon contents (0,12-0,85 g/100g). The bulk densities of all the soils were inversely related to the organic carbon content and this was itself related to the clay content of the soils. The bulk densities of the sands were dependent on the grading of the sand fraction. Many of the soils were sensitive to remoulding in the Emerson test and the sands to loany sands had 0,4-1,0 g/100 g water dispersible clay. Measurements of tensile strength on air-dry samples showed that all the soils, except for one sand, set hard after a wetting and drying cycle, giving for vacuum wet samples indirect tensile strengths 1,0-14,4 kPa. For the sands to sandy loams this strength was related to the water dispersible clay content. Samples wet at atmospheric pressure were weaker than the vacuum wet samples, the reduction in strength was related to the air porosity of the non-vacuum wet soils prior to drying. Remoulding the soils prior to drying them increased the strength by a factor of up to 50 times, giving strengths from 4 kPa to 600 kPa. The strength after remoulding was dependent on the Emerson index. Compacting the soils increased their strength greatly and to an extent that agreed with the hypothesis that the strength obtained was proportional to the area of contact between the particles. Experiments on penetration resistance at a range of water contents were performed on a few soils. A hyperbolic relationship between water content and penetration resistance of the surface soil was found for sand to sandy loam soils, with the maximum resistance of dry soils above 2 MPa. The penetration resistance of the sandy loam soil was Increased three times by disturbing it when wet. Sprinkler wetting the sieved soils was not found to affect the penetration resistance by a large amount compared and other methods of welting. Penetration resistance was measured on air-dry samples of most of the main group of soils following varying degrees of wetting with a rainfall simulator. The clays and hydromorphic soils gave very low values of penetration resistance under these conditions, showing that at organic carbon contents of about 1% and clay contents from 20 to 30%, the decreased bulk density and tendency to form aggregates' on drying overcame the tendency to set hard. The mean values for the sands to sandy loams were from 1 to 6 MPa so all these soils could offer significant resistance to a sorghum seedling. The penetration resistance of the sands and loam/ sands depended on their bulk densities and water dispersible clay contents, while the penetration resistance of the sandy loams depended only on the water dispersible clay content.
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Stomph, Tjeerd Jan. "Seedling establishment in pearl millet (Pennisetum glaucum (L.) R.Br.) : the influence of genotype, physiological seed quality, soil temperature and soil water." Thesis, University of Reading, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.276632.
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McElhannon, Laura Michelle Waters Luther. "Enhancement of seed germination and seedling growth of Lenten rose." Auburn, Ala., 2008. http://repo.lib.auburn.edu/EtdRoot/2008/SUMMER/Horticulture/Thesis/Moore_Laura_47.pdf.
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Peacock, Kenneth. "Growth, mechanical stress responses and mutation of sunflower seedling hypocotyls." Thesis, University of Aberdeen, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.277289.
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The aims of this thesis were four-fold: 1. To characterise the patterns of growth underlying established nutations of etiolated sunflower seedling hypocotyls. 2. To characterise the growth patterns and events surrounding the initiation of nutation in etiolated sunflower seedling hypocotyls. 3. To investigate the effects of applied compression and tension forces on the straight growth of etiolated sunflower seedling hypocotyls. 4. To investigate the relationship between auxin and the responses to mechanical stress in etiolated sunflower seedling hypocotyls. Time-lapse video analysis showed that the growth of etiolated sunflower seedling hypocotyls was more dynamic than expected, with growth constantly changing. When growth rates were plotted against time, the resultant curves showed regular oscillations similar to those of the movement traces for nutation and it was apparent that the nutational movements were intimately linked to the patterns of growth. Such patterns of growth were also found prior to the onset of nutation but in that case the growth curves on opposite sides of the hypocotyl did not oscillate out of phase with each other until immediately before the start of nutation. It was also found that there was a threshold height below which nutations were never found. The roles of light and geotropic responses in the initiation of nutation were also investigated. It was found that light was not required for nutation to occur and that various types of geotropic stimulation failed to initiate nutation in seedlings below the threshold height, although such seedlings were capable of responding to a gravity stimulus. It was concluded that the initiation and maintenance of nutation is an endogenous process and that nutation is a result of the way in which seedling hypocotyls grow rather than a discrete phenomenon superimposed on `normal' growth. The application of compression forces increased the growth of etiolated sunflower seedling hypocotyls over that of the non-compressed controls while tension forces applied to the same material did not produce any significant change in growth rates. When compression forces were applied to seedlings immersed in 10-10 Molar auxin solution the increase in growth due to compression were larger than those found for seedlings compressed while immersed in distilled water. It was concluded that some mechanism for the reception of compression forces operates in this material possibly involving a change in the sensitivity of the epidermal cells to auxin. A model was proposed in which growth is controlled by the mechanical forces acting on individual cells. It is suggested that nutation arises from the responses of cells and groups of cells to such mechanical strains.
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Magnitskiy, Stanislav V. "Controlling seedling height by treating seeds with plant growth regulators." Connect to this title online, 2004. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1101741472.
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Thesis (Ph. D.)--Ohio State University, 2004.<br>Title from first page of PDF file. Document formatted into pages; contains xix, 157 p.; also includes graphics. Includes bibliographical references (p. 147-157).
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FitzGerald, Véronique Chartier. "Ectomycorrhizal fungal assessment of South African Pinus patula seedlings and their biological control potential to enhance seedling growth." Thesis, Rhodes University, 2019. http://hdl.handle.net/10962/67902.
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Self, Guy K. "Studies of xylopodium formation and early seedling growth in Kielmeyera coriacea Mart." Thesis, University of Edinburgh, 1989. http://hdl.handle.net/1842/14374.
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Verheul, Michel J. "Seedling growth of maize (<> L.) genotypes under chilling conditions /." [S.l.] : [s.n.], 1992. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=9855.
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Moss, Stuart Alan. "Nitrogen availability and pine seedling growth in organically- amended mine soils." Thesis, Virginia Polytechnic Institute and State University, 1986. http://hdl.handle.net/10919/101135.
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Adequate supply and availability of nitrogen (N) is a major factor hindering successful revegetation of reclaimed surface mines. Because topsoils are often unrecoverable, “topsoil substitutes”, made up of overburden materials devoid of N, are often used on reclaimed surfaces. Four replications of seven surface treatments were applied to 12 m² plots of 2:1 sandstone:siltstone material on a reclaimed coal surface mine in Wise Co., VA: 1) fertilizer (168 kg/ha N, 147 kg/ha P, and 139 kg/ha K), 2) limed (7.8 Mg/ha), fertilized topsoil (30 cm deep), 3) 112 Mg/ha sawdust + fertilizer + 336 kg/ha slow-release N, and 4-7) lime-treated municipal sewage sludge at rates of 22, 56, 112, and 224 Mg/ha. Nitrogen availability after 40 mo (as determined by aerobic and anaerobic incubations) in sawdust- and sludge-amended soils was two to 20 times higher than in fertilized and topsoil-amended soils. Moisture holding capacity was nearly twice as high in sawdust-amended soils as in all other treatments. Soil nitrate (NO₃⁻) levels (0-20 cm layer) in excess of 75 μg/g were detected in the 112 and 224 Mg/ha sludge plots 28 mo after application. Stem volumes of three-year-old pitch X loblolly pines (<i>Pinus rigida</i> X <i>taeda</i>) were four times larger in soils amended with sawdust + slow-release N and were twice as large in soils amended with 22 and 56 Mg/ha sludge compared to fertilized-only seedlings. Increased seedling mortality was observed in the 112 and 224 Mg/ha sludge treatments, possibly due to high soluble salt levels and/or manganese deficiencies. The availability of N from sawdust + slow-release N or sludge (≤ 56 Mg/ha) is better than that of inorganic fertilizer for sustained tree growth. These amendments are recommended for reclamation to the extent that they are economically available.<br>M.S.
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Ali, Md Gous. "The effects of low temperature and seed quality on the germination of fifteen rice (Oryza sativa L.) cultivars from Bangladesh." Thesis, University of Aberdeen, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.369730.
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The responses of 15 rice cultivars to low temperature during germination were studied in order to develop appropriate techniques to identify rice genotypes suitable for direct-wet seeding in the cooler <I>Boro</I> season. Most rice cultivars showed more than 90% final germination over a range of temperatures. When tested at 13.7°C, cultivars differed in their final germination and rate of germination. The rates of germination at higher temperatures were significantly related to the rates of germination at lower temperatures. Thermal times to 50% final germination also differed significantly. Artificial ageing for 48 hours clearly separated the cultivars which had different K<sub>i</sub><I> </I>(initial seed viability). Such measures of physiological age and their relationship with final germination suggested that low quality seed exhibited reduced low temperature germination. Differences in rates and final germination at lower temperature of unaged seed suggested genotypic differences between cultivars. Inconsistency in rates of seed deterioration was seen contrary to conventional theory. Storage of seeds up to 9 weeks in simulated Bangladeshi conditions showed reductions in final germination tested at 11°C but not at 20°C. The rates of chitting and germination were increased by pregermination hydration treatments. Emergence of rice cultivars from soil was greater in constant than in alternating temperatures. Higher final emergence was associated with faster emergence. Thermal time to 50% and 80% emergence differed between cultivars. Many of the seedling growth parameters were higher in constant temperatures where the rate of germination was faster. The outcome of these experiments is to highlight the potential for comparing rates of germination of large numbers of genotypes relatively rapidly at higher temperatures as a measure to predict germination at lower temperatures.
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Bryan, James Alfred. "The effects of growth medium acidity, exogenous growth regulators, and nitrogen fertilizer on the acceleration of Fraser fir seedling growth." Thesis, This resource online, 1988. http://scholar.lib.vt.edu/theses/available/etd-04272010-020339/.
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Masamba, Christopher Riach Liamba. "Factors influencing accelerated seedling growth in Malawian provenances of Faiherbia Albida del." Thesis, Imperial College London, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.392122.
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Kuo, Eva Grotkopp. "Genome size evolution, seedling relative growth rate, and invasiveness in pines (Pinus) /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2003. http://uclibs.org/PID/11984.
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Cardoso, Danúbia Gonçalves. "Phytotoxic activity of auxin on germination and seedling growth of Stylosanthes humilis." Universidade Federal de Viçosa, 2015. http://www.locus.ufv.br/handle/123456789/8373.
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Previous issue date: 2015-07-10<br>Coordenação de Aperfeiçoamento de Pessoal de Nível Superior<br>Apesar dos efeitos das auxinas, em altas concentrações, no crescimento das plantas ser bem conhecido, pouco se conhece sobre os seus efeitos durante a transição de sementes para plântulas. Este estudo foi realizado para avaliar o efeito da biossíntese de etileno e do ajuste metabólico em resposta a auxina, durante a germinação das sementes e no crescimento de plântulas de Stylosanthes humilis. Em sementes dormentes de S. humilis, auxina, em elevada concentração, inibiu a atividade da oxidase do ácido 1- aminociclopropano-1-carboxílico (ACO). Por outro lado, a biossíntese do ácido 1- aminociclopropano-1-carboxílico (ACC) e a produção de etileno em plântulas aumentaram quando tratadas com auxinas, o que foi associado com a inibição do crescimento das plântulas. Além disso, auxina inibiu a biossíntese do ACC em sementes não-dormentes de S. humilis. Em conjunto, estes dados indicam que o efeito da auxina, em alta concentração, no controle e no metabolismo do etileno é de fato temporalmente separado. Além disso, o ácido 2,4-diclorofenoxiacético (2,4-D) induziu dormência secundária em sementes de S. humilis, o que foi associado com um mecanismo de reserva de energia. Além disso, a dormência secundária de sementes tratadas com 2,4-D foi quebrada por solução de ACC. Assim, este estudo revelou a existe de um mecanismo em que a mobilização de reservas e a biossíntese de etileno se conectam para regular a transição do desenvolvimento das sementes dormentes para o crescimento plântulas.<br>Although auxins, at high concentrations, are well known for their effects on plant growth control, little is known about their effects during seed-to-seedling transition. This study was carried out to evaluate the modulation of ethylene biosynthesis and metabolic adjustment in response to auxin during seed germination and postgermination growth of Stylosanthes humilis. In freshly harvested seeds (dormant seeds) of S. humilis, auxin, at high concentration, repressed the 1-aminocyclopropane-1-carboxylic acid (ACC) oxidase activity. On the other hand, ACC biosynthesis and ethylene production by seedlings were increased by auxin treatments, which was associated with seedling growth inhibition. Furthermore, auxin inhibited ACC biosynthesis in aged seeds (non-dormant seeds). Together, these data indicate that the effect of high levels of auxin in the control of ethylene metabolism is developmentally separated. In addition, 2,4-dichlorophenoxyacetic acid (2,4-D) induced secondary dormancy in aged seeds of S. humilis, which was associated with the operation of energy-saving metabolism. Moreover, secondary dormancy of 2,4-D treated seeds was broken by ACC solution. Thus, this study has revealed a process in which storage reserves mobilization and ethylene crosstalk in regulating the developmental transition from metabolic quiescent seed to actively growing seedling.
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Farifr, Eiman. "Seedling growth and physiological responses of Perth’s eucalypts to soil-induced stresses." Thesis, Curtin University, 2010. http://hdl.handle.net/20.500.11937/1865.
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Perth’s Swan Coastal Sand Plain soils are typically nutrient impoverished, and the native trees of the region are therefore adapted to maximise nutrient uptake. Although the dune systems here are generally not known to be particularly saline or alkaline, there are areas that susceptible to salinity, flooded and elevated pH, especially those that have been modified by human activities. This study investigated the seedlings growth of three Eucalyptus species (Corymbia calophylla, Eucalyptus gomphocephala and E. marginata) to three environmental stress; salinity waterlogging and alkalinity in a greenhouse at Curtin University to assess their relative tolerance to these stressors, and hence understand more about their potential use in landscape restoration and rehabilitation. Knowing the seedling growth and physiological responses of three prominent Perth eucalypts to soil-induced stresses provides us with invaluable knowledge for rehabilitating and restoring Perth’s urban bushland.For the salt tolerance experiment, seedlings of the three species were subjected to 81 days growing in potting mix watered weekly with either 0, 50, 100, 150, 250 mM NaCl solutions. Measurements of relative plant growth, biomass allocation and leaf water loss and seedling survival suggested that E. gomphocephala was the most tolerant. Survival data suggests that E. gomphocephala seedlings have shown ability to cope with a weekly dosage of NaCl solution much greater than 0.25 M, and at least survived for more than 11 weeks under moderately saline conditions. Corymbia calophylla, and E. marginata were the least tolerance with more than half the seedlings succumbing to salt solutions > 250 mM NaCl.A flooding experiment, caused by prolonged inundation of water, lasting for 70 days, all three species grew most vigorously in well watered condition but when waterlogged condition E. gomphocephala and E. marginata seedlings grew slowly and became more water stressed compared to C. calophylla seedlings. These finding suggest that although E. gomphocephala and E. marginata can occurs in wetter areas of Perth’s Swan Coastal Plain they are not flood tolerant. C. calophylla is a common tree species in the moderately wet lower south-west of Western Australia; it is less common north of Perth where it is restricted to river valleys (Powell 2009). This may explain Marri’s ability to physiologically tolerate seasonal flooding (i.e. no significant reduction in stomatal conductance or transpiration rate), despite a reduction in seedling growth.A liming experiment, was conducted with 20% w/w crushed and sifted Tomala limestone add to potting mix to increase soil pH. The pot trial was conducted over 82 days. E. gomphocephala is restricted soils overlying limestone on Perth’s Swan Coastal Plain, and according to total seedling dry weight data and calculated relative growth rates coped best in a limestone-enriched soil. However, when examining all the growth and physiological data collected C. calophylla appears to be the most tolerant, with no significant difference in leaf allocation or leaf water loss between the well-watered controls and the limestone-enriched treatments. E. marginata was the least tolerant with a 14% reduction in stomatal conductance.As seedlings, E. marginata was the least tolerant to the three soil-induced stresses (i.e. flooding, salinity, alkalinity) imposed. The next most tolerant species, E. gomphocephala wasn’t the most tolerant to an increase is soil alkalinity, although it displayed the least change in seedling dry weight and relative growth rate. C. calophylla was the most tolerant of the three eucalypts to the three stressors. However soil-induced stresses will last for longer than the 70-80 days when plants are growing in more natural environments than the seedlings were exposed to in these experiments. By itself, these results will assist Perth’s urban land managers in understanding how these tree species respond at the seedling stage to three important soil-induced stressors, more work is required to understand how the observed responses after seedling physiology and how long the seedlings can tolerate these extreme changes in their growing environment.
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Bebber, Daniel Patrick. "Dipterocarp seedling growth and mortality in the understorey : roles of herbivory and drought." Thesis, University of Oxford, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.289347.
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Ali, Rao Sajjad. "The potential for breeding Zea mays (L.) for saline conditions." Thesis, University of Liverpool, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.387451.
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King, Janice Elizabeth. "The role of arginine and arginase in Pinus taeda L. early seedling growth." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ34789.pdf.
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Bahizire, François B. "Effect of salinity on germination and seedling growth of canola (Brassica napus L.) /." Link to the online version, 2007. http://hdl.handle.net/10019.1/1939.
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Norberg, Gisela. "Steam treatment of forest ground vegetation to improve tree seedling establishment and growth /." Umeå : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 2000. http://epsilon.slu.se/avh/2000/91-576-6054-9.pdf.
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Xue, Jianming. "Effects of biuret addition on soil nitrogen transformations and Douglas fir seedling growth." Thesis, University of Canterbury. Forestry, 2002. http://hdl.handle.net/10092/7595.
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This project was carried out to evaluate the feasibility of using of biuret as a plant growth and/or soil microbial activity regulator at low concentrations, and as a slow-release N fertiliser at high concentrations.
Biuret stimulated Douglas-fir seedling growth at low concentrations, but inhibited it at high concentrations. The stimulation of biuret on seedling growth in sand and solution culture was associated with increased net photosynthetic rate and nutrient uptake and when grown in the soil it was also related to the improvement of soil N availability and therefore the uptake of N by seedlings. Provenance 93 (relatively fast growing) was more responsive to lower concentrations of biuret, but more sensitive to the toxicity of biuret at high concentrations than provenance 98 (relatively slow growing). Yellow-tip (chlorosis) in needles was a typical symptom of biuret toxicity.
Applied nitrogen had a much greater effect on Douglas fir seedling growth than biuret.
Provenance 93 grew faster at lower N supply due to its greater ability to absorb more
nutrients and further to distribute more into the shoot.
Biuret at lower concentrations had a positive real priming effect on net mineralisation of native soil N in both soils. The causes for the positive priming effects were related to the stimulation of microbial growth and activity at an early stage of the incubation and/or the death of microbes at a later stage, which was biuret-concentration-dependent. Biuret additions increased gross rates of soil N mineralisation and nitrification and affected the turnover rates of mineral N pools. The biuret-¹⁵N tracing technique further confirmed that biuret addition stimulated the mineralization of native soil N by increasing the turnover rate constant (k value). The potential of biuret as a slow-release N source at high concentrations (especially in the Burnham soil) was related to the slow mineralisation, nitrification and more immobilisation of biuret-N, which reduced the potential of N losses by volatilisation and denitrification.
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Mahwood, T. "Physiology of metal ion-induced effects on germination and seedling growth in cereals." Thesis, University of Edinburgh, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.657209.
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The effects of zinc, lead and copper ions, at concentrations up to 10 mM, on germination and seedling vigour of wheat, barley and rice were investigated. Percentage germination was unaffected by lead and zinc ions in the three species tested. The highest concentration of copper ions (10 mM) decreased the percentage germination in rice. Rice seedlings were grown in controlled environment cabinets using a nutrient culture technique. A copper ion concentration of 8 μM in the culture solution was found to inhibit the elongation of the longest root. Seedlings were grown in nutrient solutions at pH 5.5, 5.0 and 4.5, and three concentrations of copper ions. The reduction in all the growth parameters was highest at pH 4.5 in all copper ion treatments. The amount of chlorophyll in the uppermost fully-expanded leaves of the seedlings grown at pH 4.5, was considerably less than that in comparable leaves of the control seedlings. The effect of copper ions on root plasma membranes of the seedlings was estimated by measuring K<SUP>+</SUP> leakage from intact roots. A larger amount of K<SUP>+</SUP> leaked from roots when seedlings were incubated with high (16 μM) copper ion concentrations than when seedling roots were incubated in water. Similarly, the effect of copper ions on root lipid peroxidation as measured by TBA-rm(2-thiobarbituric acid-reactive material) accumulation, showed that more TBA-rm was accumulated in copper ion treated roots than in control roots. The effect of various copper ion concentrations on the morphology and ultrastructure of the roots was studied using light and scanning electron microscopy. The results showed that copper ions caused a reduction in the length of the root hair zone and of root hair length, a reduction in the size of the root cells, and initiation of lateral root closer to the root tip, compared to seedlings grown in control solutions.
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Bahizire, Francois B. "Effect of salinity on germination and seedling growth of Canola (Brassica napus L.)." Thesis, Stellenbosch : University of Stellenbosch, 2007. http://hdl.handle.net/10019.1/1939.
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Thesis (MScAgric (Agronomy)--University of Stellenbosch, 2007.<br>Soil salinity is a serious constrain to crop production in many countries.
In the Western Cape canola production area, large variability in soil properties within the same field is a very common feature. Some of this variability may be ascribed to differences in salinity. These saline patches affected the germination and survival of cereal crops like wheat and may therefore also be a reason for the high variability and generally low canola yields obtained in this area. It will therefore be important to quantify the effect of such saline conditions on the germination and seedling establishment of canola in an effort to improve yields.
In this study several experiments were conducted under controlled conditions in either Petri dishes in an incubator or pots in a temperature controlled glasshouse to determine the salinity response of canola.
Results of the experiments done in Petri dishes, showed that the germination response of canola (Brassica napus L., cv. Tornado) to increasing levels of salinity is very similar to that of wheat (Triticum aestivum L., cv SST 88). Although canola germinated more rapidly than wheat at a temperature of 20 ºC, the final percentage germination for both crops decreased severely when NaCl induced salinity exceeded levels of an EC of 8 dS m-1, but less severe responses were obtained with NaCl/CaCl2 induced salinity.
Under soil conditions an interaction between soil type and salinity level showed that the responses in sandy soil to an increase in salinity from 0 to 8
iv
dS m-1 were less severe than in loamy soil and especially when salinity stress was induced by NaCl.
Although cultivar Spektrum showed more tolerance to saline conditions during the germination and seedling stages in pot experiments when compared to other cultivars tested, these results will have to be confirmed in field trails where grain yield and quality can be measured.
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Mahmood, Tariq. "Physiology of metal ion-induced effects of germination and seedling growth in cereals." Thesis, University of Edinburgh, 1995. http://hdl.handle.net/1842/12550.
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Wiant, William C. "N-Acylethanolamine (NAE) Profiles Change During Arabidopsis Thaliana Seed Germination and Seedling Growth." Thesis, University of North Texas, 2006. https://digital.library.unt.edu/ark:/67531/metadc5333/.
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An understanding of the potential roles as lipid mediators of a family of bioactive metabolites called N-acylethanolamines (NAEs) depends on their accurate identification and quantification. The levels of 18C unsaturated NAEs (e.g. NAE18:2, NAE 18:3, etc.) in wild-type seeds (about 2000 ng/g fw) generally decreased by about 80% during germination and post-germinative growth. In addition, results suggest NAE-degradative fatty acid amide hydrolase (FAAH) expression does not play a major role in normal NAE metabolism as previously thought. Seedlings germinated and grown in the presence of abscisic acid (ABA), an endogenous plant hormone, exhibited growth arrest and secondary dormancy, similar to the treatment of seedlings with exogenous Nlauroylethanolamine (NAE12:0). ABA-mediated growth arrest was associated with higher levels of unsaturated NAEs. Overall, these results are consistent with the concept that NAE metabolism is activated during seed germination and suggest that the reduction in unsaturated NAE levels is under strict temporal control and may be a requirement for normal seed germination and post-germinative growth.
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Weatherall-Thomas, Clayton Richard. "Seed dynamics and seedling survival in mainland thicket of the Eastern Cape." Thesis, Nelson Mandela Metropolitan University, 2009. http://hdl.handle.net/10948/1048.
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Subtropical Thicket is the dominant vegetation biome in the Eastern Cape. Little regeneration through seedlings has been observed in Thicket. This is of serious concern, as Thicket has been degraded over large areas of its distribution. An understanding of the seed dynamics is necessary for any restoration project. A number of possible causes for the lack of seedlings were therefore investigated. Study sites were best classified according to the biogeographical regions of the Subtropical Thicket Ecosystem Planning (STEP) project. The seed bank of Thicket is dissimilar to the aboveground vegetation, as it lacks woody species and is dominated by herbs and grasses, making little contribution to the regeneration of Thicket species. An increase in canopy cover resulted in lower soil and air temperatures, as well as light, and an increase in litter depth. Seedling abundance and species richness increases with mean annual rainfall, with woody seedlings being dominant in the higher rainfall areas, and succulent species in the lower rainfall regions. Anemochorous species dominated the germinable seed bank, and zoochorous species were more prevalent underneath the canopy, compared to open areas, an indication of active seed dispersal. No germination was recorded in many Thicket species, and dormancy mechanisms were lacking in many of the species that did germinate. Immersion in hot water increased germination in the hard seeds of Acacia karroo, whereas shade enhanced germination in small seeded Burchellia bubalina. The response of seedlings of four Thicket species with varying distribution to shade and drought was studied. Ptaeroxylon obliquum and Aloe africana are drought tolerant species, whereas Burchellia bubalina and Rhus dentata were intolerant to low soil moisture. All four species were able to grow in deep shade, although Rhus dentata would be classified as a shade avoider, unlike the other three species that are shade tolerant. This results in the four species having different regeneration niches. It was concluded that dispersal and the lack of “safe sites” for seedlings were the main limitations to seedling establishment in Mainland Thicket.
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Socolowski, Fabio. "Ecologia germinativa, relações alométricas e o efeito da massa das sementes de Tecoma stans L. Juss. ex Kunth (Bignoniaceae) sobre a emergência e desenvolvimento das plântulas /." Rio Claro : [s.n.], 2007. http://hdl.handle.net/11449/100667.
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Orientador: Massanori Takaki<br>Banca: João Domingos Rodrigues<br>Banca: Silvio Moure Cícero<br>Banca: José Marcos Barbosa<br>Banca: Márcia Balistiero Figliolia<br>Resumo: Este estudo teve como objetivo avaliar a relação entre a massa e características morfométricas de frutos e sementes de Tecoma stans, bem como relacionar a massa das sementes a suas características morfológicas, utilizando paquímetro e imagens de raios X, e fisiológicas, através da germinação, emergência e desenvolvimento inicial de suas plântulas, sob duas condições de luminosidade . a pleno sol e sombra. Além disso, também foram avaliados os efeitos de diferentes condições de temperatura e luz constantes, em laboratório, e em ambiente natural no sol e na sombra na germinação e emergência das plântulas. A massa dos frutos apresentou relações lineares significativas e positivas com suas características morfológicas e de produção de sementes. As relações entre a massa das sementes e suas características morfológicas foram positivas e significativas, porém na forma de uma função potência, sendo esta relação mais evidente com a largura do embrião. A massa das sementes também esteve relacionada a determinadas anomalias do desenvolvimento embrionário, observadas nas imagens de raios X. A germinação, a emergência e o desenvolvimento inicial das plântulas foram significativamente afetados pela massa das sementes, porém somente durante os três primeiros meses de desenvolvimento no ambiente de sol. A temperatura apresentou efeito na germinação e suas sementes germinaram tanto na luz quanto no escuro, contudo a emergência e sobrevivência das plântulas no ambiente de sol foi superior em relação ao observado na sombra.<br>Abstract: This study had the objective to evaluate the relationship between the mass and the morphometric characteristics of Tecoma stans fruits and seeds, as well as to relate the seed mass with its morphometric characteristics, utilizing caliper and X-ray images, and physiological characteristics, thought germination, emergency and seedlings initial development, under two conditions of light - at the sun and shade. More than, also were evaluated the effects of different conditions of constant temperature and light, under laboratory, and natural environment under sun and shade in the germination and emergency of the seedlings. The fruit mass presented positive, significative linear relationship with his morphological characteristics and with its seed production characteristics. The relationship between seed mass and its morphological characteristics were positive and significative, nevertheless with the model (shape) of power function, being the relationship more clear with the embryo width. The seed mass also was related to determinate anomalies of the embryo development that could be observed in the X-ray images. The germination, the seedling emergence and the initial seedling development were significative affected by seed mass, but only in the firth three months of development at the sun environment. The temperature affected Tecoma stans seed germination in both light and darkness environment, however the seedlings emergency and survival was greater at the sun environment than shade.<br>Doutor
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Lhotka, John Michael Loewenstein Edward F. "Predicting light transmittance and seedling growth across a gradient of riparian forest canopy structures." Auburn, Ala., 2006. http://hdl.handle.net/10415/1315.
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Yang, Dongsheng. "The response of two eucalypt subspecies to water stress and fertilizer at early seedling stage." Thesis, Canberra, ACT : The Australian National University, 1987. http://hdl.handle.net/1885/140223.
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Mohamed, Nadia Mussad 1952. "Effect of Ortho XE-1019 on the germination and seedling growth of two cotton cultivars." Thesis, The University of Arizona, 1989. http://hdl.handle.net/10150/277000.
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Experiments were conducted to determine if there was a residual effect of the experimental plant growth regulator Ortho XE-1019, (E)-(P-chlorophenyl)-4,4-dimethyl-2-1,2,4-triazol-l-yl)-l-penten-3-01, remaining in Deltapine 50 and 90 cottonseed obtained at three harvest dates from experiments run at the University of Arizona Marana and Maricopa Agricultural Centers in 1986. Commercial DPL 50 seed were treated with XE-1019 in a second experiment. Several growth characteristics were measured including dry weights after 7 and 12 days. Hypocotyl length was not significantly different between treatments after 12 days of growth, with one exception, nor between dates of harvest for DPL 90 and DPL 50. Other measurements sometimes had statistical differences which were more academic but would be of little consequence in obtaining a satisfactory field stand. A significant reduction of hypocotyl length resulted when seed was directly treated with XE-1019 and would result in poor emergence. Results indicated that the use of XE-1019 as a plant growth regulator on cotton would not have significant residual responses on early seedling growth of Deltapine 90 and Deltapine 50 when the resulting seed are used for planting seed in the next generation.
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Lawrence, Margaret Diane. "Studies on the mobilisation of storage reserves during germination and seedling growth of sugar beet." Thesis, University of Leeds, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.237076.
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Tenywa, John Stephen. "Crop residue influence on exchangeable aluminum, potassium availability, and seedling root growth in a oxisol /." The Ohio State University, 1993. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487844105976783.
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Fautley, Robin Hayes. "Seedling growth and survival of Abies magnifica and A. concolor as affected by mycorrhizal infection /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2004. http://uclibs.org/PID/11984.
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Oddie, Rachel Louise Annabelle. "Eucalyptus camaldulensis x globulus hybrids for saline land: Production, seedling growth and salt / waterlogging tolerance." Thesis, Oddie, Rachel Louise Annabelle (1996) Eucalyptus camaldulensis x globulus hybrids for saline land: Production, seedling growth and salt / waterlogging tolerance. PhD thesis, Murdoch University, 1996. https://researchrepository.murdoch.edu.au/id/eprint/52423/.
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The rapid development of Eucalyptus globulus Labill. plantations for the paper and pulp industry and the increasing problem of dry land salinity in the south west of Western Australia, stimulated the development of a breeding programme aimed at producing a Eucalyptus L'Herit. hybrid that combines the salt / waterlogging tolerance of selected E. camaldulensis Dehnh. clones with the high pulp quality and yield of selected E. globulus subsp. globulus families.
Controlled pollination techniques were used to produce intraspecific and interspecific hybrids. Unilateral cross incompatibility was observed between the two species. When E. globulus was used as the female parent E. camaldulensis pollen tubes failed to grow the entire length of E. globulus styles. However when E. camaldulensis was used as the female parent, interspecific crosses were successful. Five E. camaldulensis salt tolerant clones and four E. globulus families (three with known pedigree) were used to produce the crosses.
E. camaldulensis flowers were emasculated just before operculum shed. Stigma receptivity, assessed by seed production, peaked in E. camaldulensis three days after emasculation. This coincided with the style turning red and the stigma becoming enlarged, yellow and sticky. Reasonably high levels of seed (> 25 seeds per capsule and > 65 % capsule set) could also be produced when flowers were pollinated before or after day three (days 0 - 5). Pollen placed on green, dry stigmas (days 0-2) remained ungerminated until stigmas began to enlarge and become sticky. The timing of stigma receptivity varied between the E. camaldulensis genotypes.
The number of seeds produced per capsule when E. camaldulensis was selfed was 87 % less than when the clones were outcrossed. The interspecific hybrids showed a 77 % reduction in seed set compared to outcrossed E. camaldulensis. In both cases the mechanism of the partial incompatibility was not operating in the style.
Further barriers to the hybridization of E. camaldulensis and E. globulus were manifested as a high percentage of seedlings with abnormalities compared to outcrossed E. camaldulensis. The intensity of barriers to interspecific hybridization varied, with families exhibiting from 50 to 97 % abnormal progeny.
Seedlings at the two leaf stage and at six to eight months old were scored for a number of morphological characters. These were cotyledon length, cotyledon width, depth of cotyledon emargination, petiole length, lamina length, lamina width at the widest point, the vertical distance between the axillary buds at the fifth node and leaf angle (angle between the main stem and the midvein of the lamina). Overall the morphology of the hybrids (assessed by these characters) tended to be intermediate between the two parents, but more like E. globulus than E. camaldulensis.
A small number of seedlings produced from E. camaldulensis x globulus crosses were morphologically very similar to E. camaldulensis. Allozyme analysis was used to determine the parentage of these individuals. Of the six enzyme systems studied malate dehydrogenase (MDH, E.C. 1.1.1.37) and 6-phosphogluconate dehydrogenase (6PGD, E.C. 1.1.1.44) were the most useful in identifying E. camaldulensis x globulus hybrids. The seedlings from hybrid families with similar morphology to E. camaldulensis were identified as E. camaldulensis. All other seedlings from hybrid families were clearly of hybrid origin. The possible cause of the seed contamination in the controlled crosses is discussed.
Seven month old seedlings were screened for salt / waterlogging tolerance in a glasshouse trial. Seedlings were placed in tanks and flooded to the sand level in the pots with one fifth Hoagland nutrient solution number two for one week. The following and each subsequent week 50 mM NaCl was added to the tanks until the NaCl concentration reached 350 mM. This concentration was held for three weeks. E. camaldulensis had a greater salt / waterlogging tolerance than E. globulus based on survival and height growth rate. The performance of the hybrid families was intermediate between the two parental species. Genotypes with superior tolerance of saline waterlogging were micropropagated for further field trials.
The potential of selected E. camaldulensis x globulus genotypes is discussed in light of the preliminary results of the breeding programme.
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Sill, David W., Barry Tickes, and Lisa A. Carey. "Field Emergence and Seedling Growth of Lettuce as Affected by Pre-Plant/Pre-Emergent Herbicides." College of Agriculture, University of Arizona (Tucson, AZ), 1997. http://hdl.handle.net/10150/221599.
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Pre plant and pre- emergence herbicides are commonly used in lettuce production. We investigated possible effects the herbicides benefin (Balan), pronamide (Kerb) and bensulfide (Prefar) had on emergence and seedling growth of several iceberg lettuce varieties that had been primed and pelleted by seed enhancement companies The herbicide Prefar and a mixture of Balan + Prefar had the greatest impact on dry weight regardless of variety, while seedlings grown on Kerby plots were not significantly different than seedlings from untreated plots. Dry weight accumulation and field emergence were influenced significantly by pellet types and priming methods.
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Lukic, Veronika. "Examination of physiological and morphological parameters of a population of lodgepole pine, Pinus contorta Dougl. spp. latifolia, seedling roots in relation to first year seedling growth." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/mq22629.pdf.
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Jäderlund, Anders. "Bilberry (Vaccinium myrtillus L.) in a boreal forest ecosystem : effects on tree seedling emergence and growth /." Umeå : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 2001. http://epsilon.slu.se/avh/2001/91-576-6072-7.pdf.
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Boe, Brian Jeffrey Dickson Kenneth L. "Evaluating tree seedling survival and growth in a bottomland old-field site implications for ecological restoration /." [Denton, Tex.] : University of North Texas, 2007. http://digital.library.unt.edu/permalink/meta-dc-3998.
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Kilroy, Hayley A. "Enrichment planting of an understory palm: Effect of microenvironmental variables on seedling establishment, growth, and survival." Miami University Honors Theses / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=muhonors1209495979.
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Lash, Kevin D. "Facilitative effects of dead Amur honeysuckle (Lonicera maackii) shrubs on native tree seedling growth and survival." Miami University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=miami1540296714970484.
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Boe, Brian Jeffrey. "Evaluating Tree Seedling Survival and Growth in a Bottomland Old-field Site: Implications for Ecological Restoration." Thesis, University of North Texas, 2007. https://digital.library.unt.edu/ark:/67531/metadc3998/.
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In order to assess the enhancement of seedling survival and growth during drought conditions, five-hundred bare-root seedlings each of Shumard oak (Quercus shumardii Buckl.) and green ash (Fraxinus pennsylvanica Marsh.) were planted each with four soil amendments at a Wildlife Management Area in Lewisville, Texas. The treatments were a mycorrhizal inoculant, mulch fabric, and two superabsorbent gels (TerraSorb® and DRiWATER®). Survival and growth measurements were assessed periodically for two years. Research was conducted on vegetation, soil, and site history for baseline data. Both superabsorbent gels gave significant results for Shumard oak survival, and one increased green ash diameter. For overall growth, significant results were found among DRiWATER®, mycorrhizae, and mulch treatments.
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Wyss, Lozano Hoyos Tania. "Pinus elliottii var. densa Seedling Performance Reflects Ectomycorrhizas, Soil Nutrient Availability and Root Competition." Scholarly Repository, 2010. http://scholarlyrepository.miami.edu/oa_dissertations/496.
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Ectomycorrhizas generally improve seedling mineral nutrition and growth, so I hypothesized that decline of the Florida native pine variety Pinus elliottii var. densa Little & Dorman is related to deficiency of appropriate ectomycorrhizal (ECM) fungi in the pine's native flatwoods. At Archbold Biological Station I examined how quickly ECM fungi colonize P. elliottii var. densa seedlings and I compared the effect of local absence versus presence of adult pines on ECM colonization and pine seedling performance. Under controlled greenhouse conditions, I investigated how a wide range of ECM colonization and spread of extraradical mycelium throughout a large volume of relatively infertile, flatwoods soil enhance the mineral nutrition and growth of pine seedlings. In a field bioassay, I transplanted two-month-old pine seedlings to three flatwoods sites with low (4 pines/400 square m), medium (9 pines/400 square m), and high (19 pines/400 square m) adult pine densities. I subsequently excavated seedlings every two weeks for four-and-a-half months and determined their ECM colonization, response to shade, and response to surrounding grass density. Across all sites, pine seedlings in high shade had a higher mean chlorophyll concentration and lower stem dry weight than in full sun. Competition with grass reduced seedling survival and stem dry weight. Initial colonization was rapid and not different among sites, with 5.4 % of roots colonized 15 days after transplant. Pine seedlings had midpoint means of 29.5 %, 18.1 % and 21.3 % ECM root tips in low, medium and high adult pine density sites, respectively, suggesting that pine seedlings establishing in flatwoods encounter sufficient ECM fungi to support their growth, regardless of adult pine density. In a field experiment, I determined in the presence versus absence of adult pines if pine seedlings had higher ECM colonization and consequent improved survival, mineral nutrition, and growth. Within and beyond pine stands, I transplanted seedlings into intact or drilled, hyphae in-growth pipes buried in the ground. I placed autoclaved or fresh ECM root inoculum in two sets of intact pipes, and autoclaved inoculum in drilled pipes into which mycorrhizal hyphae could extend from the surrounding vegetation. Seven-and-a-half months after transplant, ECM hyphae had penetrated the drilled pipes and colonized pine seedlings, but roots from the surrounding vegetation also penetrated pipes. Extraneous roots reduced the survival of seedlings both within and beyond pine stands, but extraneous roots reduced seedling growth only beyond pine stands. Because percentage ECM root tips was higher in the presence (53 %) than in the absence (38.8%) of adult pines, pine stands might benefit the competitive ability of seedlings by increased ECM colonization and possibly by common mycorrhizal networks connecting seedlings to adults. Because beneficial effects of ECM in the field were small, I also examined ECM effects on pine seedlings in a greenhouse experiment. I manipulated ECM fungus colonization and the volume of flatwoods soil to which extraradical mycelium had access. In a small volume of soil (220 mL), fresh ECM root inoculum promoted the mycorrhizal colonization of seedlings versus those receiving autoclaved roots, but seedling growth and uptake of Mg, Ca, and Zn was lower with fresh than with autoclaved root inoculum. Growth and mineral nutrient uptake likely was enhanced by a pulse of nutrients from autoclaved roots, but for inoculated plants may have been reduced because of nutrient retention by saprotrophic microorganisms degrading fresh ECM roots and because of mineral nutrient retention by ECM fungi. Ectomycorrhizal seedlings with extraradical mycelium access to a large soil volume had higher mean chlorophyll concentration than those in a small soil volume. Weekly disturbance of the extraradical mycelium, however, reduced foliar contents of Mn, K, P, N, and Zn by one-third to one-half, and reduced needle dry weight of seedlings by one-third, demonstrating the importance of extraradical mycelium accessing a large volume of soil when it is nutrient-poor. My research demonstrates that ECM fungi are widespread in flatwoods and rapidly colonize pine seedlings. ECM fungus inocula are greater in the presence than in the absence of adult pines, and ECM or seedlings' connections to a common mycorrhizal network improve seedlings' belowground competitive ability. ECM especially enhance seedling mineral nutrition and growth when undisturbed, extraradical mycelium extends throughout a large volume of soil. Populations of Pinus elliottii var. densa might best regenerate in flatwoods if seedlings recruit near adult pines and where there is little competition for light, water, and mineral nutrients.
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Sparks, Grace Beehler. "Influence of forest-clearcut edges on fungal fruiting, litter decomposition and seedling growth in low elevation second-growth conifer forests in Western Washington /." Thesis, Connect to this title online; UW restricted, 2003. http://hdl.handle.net/1773/5533.
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