Dissertations / Theses on the topic 'Plant reproduction'
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1
Luijten, Sheila Helen. "Reproduction and genetics of fragmented plant populations." Amsterdam : Amsterdam : Instituut voor Biodiversiteit en Ecosysteemdynamica (IBED) ; Universiteit van Amsterdam [Host], 2001. http://dare.uva.nl/document/60623.
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Jordan, Crispin Yves. "Studies investigating evolutionary transitions in plant reproduction." Thesis, University of British Columbia, 2011. http://hdl.handle.net/2429/36436.
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In this thesis I explore several topics related to the evolution of plant reproductive characters.
First, I consider mating system evolution at a single locus that simultaneously affects multiple fitness components, including pollen export, selfing rate, and viability (i.e., survival or a similar change in male and female function). I use two approaches. First, I assume frequency-independent mating, so the model characterizes prior selfing (Chapter 2). Second, I assume that selfing rates are determined by a "mass action" process, which characterizes several additional modes of selfing (Chapter 3). For both approaches, pleiotropy between increased viability and selfing rate reduces opportunities for the evolution of pure outcrossing, can favor complete selfing despite high inbreeding depression, and notably, can cause the evolution of mixed mating despite very high inbreeding depression. These results suggest that selection by non-pollinating agents may help explain mixed mating, particularly in species with very high inbreeding depression.
Second, I analyze the potential for different genome regions to harbor intra-locus sexually-antagonistic polymorphism. Such polymorphism, involving one allele that benefits fitness in males but decreases fitness in females, and a second allele with opposite effects, is believed to influence the evolution of sexual dimorphism and sex chromosome evolution; both have evolved repeatedly among plant lineages, so understanding the potential for sexually-antagonistic variation informs the evolution of dioecy. Numerical analyses confirm the previous major conclusion that sexually-antagonistic polymorphisms are generally maintained in a larger region of parameter space if the locus is in the pseudo-autosomal region than if it is autosomal.
Finally, I consider the effect of two stressors on time to flowering to address hypotheses regarding the evolution of flowering time in heterogeneous environments. A greenhouse experiment using Mimulus guttatus revealed that low water and herbivory had opposite effects on time to flowering, although these effects were weak. These stressors had stronger influences on plant height and the number of flowers produced. These data, combined with previously published results, suggest that a stressor's effect on non-phenological traits may influence the evolution of flowering time through mechanisms not considered by previously published theoretical studies.
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Forster, Anthony Carlyle. "Self-cleavage of plant pathogenic RNAs." Title page, contents and summary only, 1987. http://web4.library.adelaide.edu.au/theses/09PH/09phf7331.pdf.
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Maier, Camelia G. A. (Camelia Gabriela-Anca). "Phytoestrogens in Two Dioecious Species: Isolation, Characterization and Role in Plant Reproduction." Thesis, University of North Texas, 1996. https://digital.library.unt.edu/ark:/67531/metadc332478/.
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A highly specific steroid regulated transcription system system in Saccharomyces cerevisae was used to screen for phytoestrogens indioecious plants. Yeast cells were co-transformed with a human estrogen receptor expression plasmid and a reporter plasmid containing the E. coli β-galactosidase gene.
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Wyka, Tomasz P. "Storage, growth and reproduction in an alpine herbaceous plant, Oxytropis sericea /." free to MU campus, to others for purchase, 1999. http://wwwlib.umi.com/cr/mo/fullcit?p9946316.
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Iglesias, Maria Claudia. "Spacial patterns of the genders in Dioecius plant species." Thesis, McGill University, 1986. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=65458.
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Nam, Ki Jung. "Host-plant acceptance by aphids : cues initiating reproduction." Thesis, Imperial College London, 2010. http://hdl.handle.net/10044/1/6397.
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The host-plant acceptance behaviour of aphids was examined, in two aphid species, the bird cherry-oat aphid, Rhopalosiphum padi and the pea aphid, Acyrthosiphum pisum, to elucidate the recognition factors used to assess plant suitability for parthenogenetic reproduction. In addition, host-plant chemistry was investigated to study possible cues that initiated reproduction. The probing and parturition behaviour of R. padi on barley, Hordeum vulgare, or bird cherry leaves, Prunus padus, were monitored by electrical penetration graph (EPG) coupled with a simultaneous video recording. The autumn winged gynoparae and the summer winged virginoparae initiated reproduction on their host plants, P. padus and H. vulgare, respectively, before phloem contact occurred and these findings suggest that phloem contact is not necessary for host-acceptance decisions. Host acceptance behaviour of A. pisum, on susceptible and phloem-based resistant line of Medicago truncatula was monitored and found to be similar on both plant lines. The phloem-based resistance mechanism did not affect parturition behaviour indicating that reproduction is initiated prior to phloem contact. The results also imply that sign chemicals used as host recognition cues located in a peripheral tissue rather than in the phloem of host plants. Bioassays were employed to characterise the sign chemicals within host-plants of R. padi. It was found that virginoparae reproduced similarly on a neutral medium such as water or holidic diet as well as host-plant aqueous extract, which suggests that particular stimulants may be not involved in host-plant recognition by this generalist morph. On the other hand, aqueous extracts of bird cherry leaves specifically stimulated parturition in autumn gynoparae. Bioassay-guided chemical fractionation showed that at least five secondary metabolites appear to be involved in host recognition by gynoparae.
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Wissman, Jörgen. "Grazing regimes and plant reproduction in semi-natural grasslands /." Uppsala : Department of Conservation Biology, Swedish University of Agricultural Sciences, 2006. http://epsilon.slu.se/200640.pdf.
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Biddle, Kelly Denise. "An analysis of alternative forms of plant reproduction using Gossypium barbadense and Arabidopsis thaliana." [College Station, Tex. : Texas A&M University, 2006. http://hdl.handle.net/1969.1/ETD-TAMU-1158.
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Alliende, Maria Catalina. "Growth and reproduction in a dioecious tree, Salix cinera." Thesis, Bangor University, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.280693.
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Amaya, Iraida. "Centoradialis and the control of plant architecture." Thesis, University of East Anglia, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.302230.
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Gough, M. W. "Relationships between leaf demography, growth and reproduction in winter annuals." Thesis, University of Leeds, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.383999.
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Fairbanks, Meredith Margaret. "The effect of the fungicide phosphite on some aspects of plant reproduction." Thesis, Fairbanks, Meredith Margaret (2001) The effect of the fungicide phosphite on some aspects of plant reproduction. PhD thesis, Murdoch University, 2001. https://researchrepository.murdoch.edu.au/id/eprint/51677/.
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Phytophthora cinnamomi Rands is a plant pathogen capable of infecting about 20% of native plant species in the south-west of Western Australia. The fungicide phosphite (phosphonate) provides an inexpensive and effective control of the pathogen. Phosphite can be applied by injection, soil drench, spray to run-off and misting. In the Mediterranean climate of the south-west of Western Australia operational sprays to native plant communities are applied in autumn or spring.
The up-take of phosphite was compared using spraying foliage to run-off with 0, 2.5, 5 and 10 gL-1 and misting with 100, 200 and 400 gL-1 phosphite. High Performance Ion Chromatography showed that the phosphite concentration in shoot apices of Corymbia {Eucalyptus) calophylla (marri) sprayed to run-off with 5 gL-1 phosphite, was comparable to the concentration in shoot apices of plants misted with 100 gL phosphite. In plants sprayed with 10 gL-1 phosphite the concentration in shoots was comparable to that in plants misted with 200 or 400 gL-1 phosphite. In root apices, spray to run-off at 5 and 10 gL-1 phosphite gave comparable concentrations to a 100 and 200 gL-1 phosphite mist treatment. Operational treatments of native vegetation are carried out at 5 gL-1 phosphite for spray and 400 gL-1 phosphite for mist. The results on marri suggest that these treatments are not comparable in terms of phosphite uptake. Analysis of additional species is required to determine whether the concentrations used should be reviewed to obtain comparable results from spraying and misting.
Phosphite has in general, low phytotoxicity to vegetative plant parts, but its effect on sexual reproduction had not previously been evaluated. The effect on pollen fertility was studied in detail and it was shown that in some species pollen fertility was significantly reduced for many months after spraying. Phosphite had a varying effect on sexual reproduction of some annuals in the Eucalyptus marginata (jarrah) forest. It reduced pollen fertility of the annual Pterocheata paniculata when plants were sprayed in the vegetative stage and of Pt. paniculata, Podotheca gnaphalioides and Hyalosperma cotula when sprayed at anthesis. Seed germination was reduced by phosphite, in Pt. paniculata and H. cotula when plants were sprayed in the vegetative stage, and in H. cotula when sprayed at anthesis. Phosphite at concentrations of 5 and 10 gL-1 killed a proportion of plants from all 3 species with up to 90% of Po. gnaphalioides plants dying.
Phosphite also affected sexual reproduction of some perennial species of the jarrah forest. In Dryandra sessilis, which flowers from autumn to early spring, pollen fertility was reduced by phosphite for up to 35 and 60 weeks after spraying in spring and autumn, respectively. Seed germination was not affected by phosphite. Pollen fertility of Trymalium ledifolium, a winter to early spring flowering species, was reduced by phosphite for up to 38 and 61 weeks after spraying in spring and autumn, respectively. Seed germination was reduced by phosphite 11 weeks after a spring spray. Phosphite was still detected in T. ledifolium shoots 62 weeks after spraying. In Lasiopetalum floribundum a species that flowers in spring, pollen fertility was reduced for 3 weeks when sprayed in spring. There was no effect on seed germination. Phosphite was also found to reduce pollen fertility of perennial species from the northern sandplains of Western Australia for up to 8 months after spraying.
The deleterious effect of phosphite was shown to be partly a result of its effect on cell division. Model plants Vicia faba. Petunia hybrida and Tradescantia virginiana, which are used for cytological research and are readily available and fast growing, were used to study this interaction. Phosphite significantly increased the number of chromosome laggards and bridges/stickiness in mitotic cells in the root tips of V. faba and P. hybrida sprayed with phosphite. Phosphite also increased the number of univalents and micronuclei in T. virginiana pollen microspore cells. The levels of abnormality. although significant, were not large enough to account for the level of pollen sterility observed.
Another mechanism for the effect of phosphite was the disruption of the normal timing of tapetum breakdown. Phosphite at 20 gL-1 brought about the premature breakdown of the tapetum in P. hybrida, and a small alteration in protein synthesis in the tapetum of treated plants, 7 days after spraying.
Phosphite has mutagenic properties. The Ames in vitro spot test showed that 400 gL-1 phosphite increased the number of DH5a Escherichia coli mutants by 60%. Tests of 24 hour cultures of this E. coli strain in solutions of 0.4, 4, and 40 gL-1 phosphite resulted in an increase in mutation rate by a factor of 10 to 100. Phosphite reduced E. coli growth after 24 hours exposure at concentrations as low as 0.4 gL-1.
From the findings of this thesis, it is recommended that the current management and application of phosphite be reviewed. The concentrations of phosphite that are currently applied as spray to run-off or mist are not comparable and measures should be taken to ensure that the application methods are comparable if equivalent effects are expected. Phosphite was found to have deleterious effects on plant sexual reproduction of both annual and perennial native Australian species. When species are in flower at the time of phosphite application, their pollen fertility is significantly reduced. It would be beneficial therefore to spray when plants are not in flower. However, due to the limited period of ideal climatic conditions for aerial application, in autumn and spring, it is not feasible to apply phosphite at other times. However, when the treatment is being applied in order to protect rare species, it would be advisable to spot spray when the species is not flowering.
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Soares, Natalia Costa [UNESP]. "Variação intra-específica na fenologia de espécies de sub-bosque de floresta Atlântica e sua relação com variáveis microambientais." Universidade Estadual Paulista (UNESP), 2011. http://hdl.handle.net/11449/87852.
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Variação intra-específica na fenologia de espécies de sub-bosque de Floresta Atlântica e sua relação com variáveis microambientais - Fatores abióticos, como a umidade relativa, temperatura e luz, influenciam o estabelecimento, desenvolvimento e reprodução das espécies vegetais florestais. Entretanto é necessária a coleta de parâmetros estruturais, microclimáticos e microambientais para a caracterização dos ambientes nos quais as plantas se desenvolvem. Neste contexto, o presente trabalho objetivou avaliar a influência de fatores do microambiente na resposta fenológica de espécies vegetais componentes do sub-bosque de floresta Atlântica, em Ubatuba, SP. Procuramos responder as seguintes perguntas: i) As plantas de sub-bosque podem ser agrupadas em relação aos ambientes de luz: borda natural, clareira e interior sombreado da floresta?; ii) Existem variações intra-específicas na fenologia das espécies de sub-bosque de Floresta Atlântica de acordo com o ambiente de luz em que foram agrupadas?; iii) A intensidade das respostas fenológicas (número de estruturas reprodutivas produzidas) está relacionada aos locais de luz?; iv) Outras condições microclimáticas, como temperatura e umidade relativa, e microambientais, como a densidade da vegetação, também influenciam a fenologia das espécies? Para tanto a fenologia e a produção de estruturas reprodutivas de quatro espécies abundantes do sub-bosque foram acompanhadas de janeiro de 2009 a abril de 2010. Indivíduos foram selecionados em ambientes previamente determinados como borda natural (beira de rio), clareira e interior de floresta atlântica. Medidas periódicas das variáveis microclimáticas (temperatura, umidade relativa, PAR) e microambiental (abertura do dossel) próximas aos indivíduos amostrados foram realizadas. Medidas estruturais...
Phenological intraspecific variation of Atlantic Forest understory species and its relation to microenvironmental variables - Abiotic factors such as humidity, temperature and light influence the establishment, development and reproduction of forest plant species. However, it is necessary to collect structural, microclimatic and microenvironmental parameters to characterize the environments in which plants grow. In this context, this study evaluated the influence of the microenvironment in the phenological response of understory plant species components of the Atlantic Forest in Ubatuba, São Paulo State. We tried to answer the following questions: i) Can the understory species be grouped in relation to natural edge, gaps and interior microenvironments? ii) Do exist intraspecific variations in the phenology of understory species of Atlantic forest in accordance with the light environment in which they were grouped? iii) Do the intensity of phenological responses (number of reproductive structures produced) related to local condictions of light?; iv) Do other microclimatic (such as temperature and relative humidity) and microenvironmental (density vegetation) conditions also influence the phenology of species? The phenology and reproductive structures production of four abundant species of the understory were followed from January 2009 to April 2010. Individuals were selected in environments previously determined as natural edge (riverside), gap and interior. We performed periodic measurements of microclimatic (temperature, relative humidity and PAR) and microenvironmental variables (canopy openness) near the sampled individuals. Structural measures (CAS, CAP, plant height, crown height from the ground and crown size) and microenvironment characterization (canopy height, understory vertical density, distance... (Complete abstract click electronic access below)
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Sheldon, Candice Claire. "Hammerhead mediated self-cleavage of plant pathogenic RNAs /." Title page, contents and summary only, 1992. http://web4.library.adelaide.edu.au/theses/09PH/09phs544.pdf.
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Braly, S. Katharine. "Environmental variables influencing sexual reproduction of sea oats, Uniola paniculata (Poaceae) across a natural dune field on Bear Island, North Carolina." View electronic thesis (PDF), 2009. http://dl.uncw.edu/etd/2009-1/r1/bralys/sbraly.pdf.
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Guazzotti, A. "GENETIC AND EPIGENETIC REGULATION OF OVULE DEVELOPMENT AND PLANT REPRODUCTION IN A. THALIANA." Doctoral thesis, Università degli Studi di Milano, 2017. http://hdl.handle.net/2434/529249.
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In angiosperms, efficient and successful reproductive strategies have been
crucial to achieve evolutionary advantages such as genetic adaptability.
However, humans, during crop domestication, selected specific traits for
agricultural benefits. Understanding the molecular mechanisms associated to
agricultural noteworthy traits, i.e. seed yield, is fundamental for genetic
improvement of crops.
On top of that, in the present thesis I will discuss four different projects, all
related to plant reproduction process, with a particular focus on phytohormones
signaling pathway and epigenetic mechanisms in the model plant species
Arabidopsis thaliana.
Cytokinin has been widely described as a key regulator of plant development and
plant reproduction. Hereby, in the first supplied work, we give a hint on the role
of CYTOKININ RESPONSE FACTORs in auxin-cytokinin crosstalk during pistil
development. Moreover, there will be an insight on unexplored molecular
mechanisms of regulation of the AUXIN RESPONSE FACTOR 5/MONOPTEROS
(ARF5/MP), such as multiple transcriptional start site and alternative splicing.
Finally, taking advantage of innovative techniques, such as Fluorescence
Activated Cell Sorting coupled to RNA sequencing, we have investigated the role
of the chromatin remodeler HISTONE DEACETYLASE 19 during ovule primordia
formation process and pollen tube ovular guidance.
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Mossman, Ronald E. "Seed Dispersal and Reproduction Patterns Among Everglades Plants." FIU Digital Commons, 2009. http://digitalcommons.fiu.edu/etd/135.
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In this study three aspects of sexual reproduction in Everglades plants were examined to more clearly understand seed dispersal and the allocation of resources to sexual reproduction— spatial dispersal process, temporal dispersal of seeds (seedbank), and germination patterns in the dominant species, sawgrass (Cladium jamaicense). Community assembly rules for fruit dispersal were deduced by analysis of functional traits associated with this process. Seedbank ecology was investigated by monitoring emergence of germinants from sawgrass soil samples held under varying water depths to determine the fate of dispersed seeds. Fine-scale study of sawgrass fruits yielded information on contributions to variation in sexually produced propagules in this species, which primarily reproduces vegetatively. It was hypothesized that Everglades plants possess a set of functional traits that enhance diaspore dispersal. To test this, 14 traits were evaluated among 51 species by factor analysis. The factorial plot of this analysis generated groups of related traits, with four suites of traits forming dispersal syndromes. Hydrochory traits were categorized by buoyancy and appendages enhancing buoyancy. Anemochory traits were categorized by diaspore size and appendages enhancing air movement. Epizoochory traits were categorized by diaspore size, buoyancy, and appendages allowing for attachment. Endozoochory traits were categorized by diaspore size, buoyancy, and appendages aiding diaspore presentation. These patterns/trends of functional trait organization also represent dispersal community assembly rules. Seeds dispersed by hydrochory were hypothesized to be caught most often in the edge of the north side of sawgrass patches. Patterns of germination and dispersal mode of all hydrochorous macrophytes with propagules in the seedbank were elucidated by germination analysis from 90 soil samples collected from 10 sawgrass patches. Mean site seed density was 486 seeds/m2 from 13 species. Most seeds collected at the north side of patches and significantly in the outer one meter of the patch edge (p = 0.013). Sawgrass seed germination was hypothesized to vary by site, among individual plants, and within different locations of a plant’s infructescence. An analysis of sawgrass fruits with nested ANOVAs found that collection site and interaction of site x individual plant significantly affect germination ability, seed viability, and fruit size (p < 0.050). Fruit location within a plant’s infructescence did not significantly affect germination. As for allocation of resources to sexual reproduction, only 17.9% of sawgrass seeds germinated and only 4.8% of ungerminated seeds with fleshy endosperm were presumed viable, but dormant. Collectively, only 22% of all sawgrass seeds produced were viable.
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Saka, Kamel. "REGENERATION OF COTTON (GOSSYPIUM HIRSUTUM L.) CALLUS PROTOPLASTS TO MACROCALLI." Thesis, The University of Arizona, 1985. http://hdl.handle.net/10150/275376.
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Dhanaraj, Bhavya. "Effect of short duration high temperature stress on bambara groundnut (Vigna subterranea (L.) Verdc.) plant reproduction." Thesis, University of Nottingham, 2018. http://eprints.nottingham.ac.uk/49191/.
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Agricultural production is at the mercy of uncertainties driven by climate change, as a result of this most of the major and minor crops are under threat of crop failure due to the severity of its effects on ‘crop fertility’. Plant reproduction is regarded as highly sensitive to such climatic changes, especially under high temperatures stress. Therefore, a key strategy to adapt to ever-increasing global temperature is by improvement and promotion of underutilised crops, one such future crop and the main focus of our research is bambara groundnut (Vigna subterranea [L] Verdc.). The present research was aimed at investigating the effect of temperature stress on plant reproduction, however, there is very limited data on how bambara groundnut genotypes differ in their response to temperature stress with respect to plant reproduction. Therefore, the focus of this research was a systematic study to establish firstly a guide to the reproductive development and, to quantify the impact of high temperature stress on floral development, pollination to fertilization and pod set in bambara groundnut. The main methodology applied to establish the first guide to bambara groundnut flower development and pollen formation was through advanced microscopy techniques (fluorescence and scanning electron microscopy [SCM]). Later, the effect of short duration high temperature stress surrounding flowering time (pre- and post-anthesis) in seven bambara groundnut genotypes (IITA-686, S19-3, AHM-753, Uniswa red, Getso, and DipC), was investigated by applying three days of high temperature stress (36/33°C, day/night) at 100% flowering, before the temperature was returned to control conditions (28/22°C) and maintained until pod harvest. Phenotypic characteristics such as flower morphology, pollen viability and pod set, between control and heat stressed groups, were some of the traits observed to assess the effect among the seven genotypes. RNA sequencing experiment was designed and executed to obtain differential gene expression data under high temperature stress, however breakdown of a freezer prevented the successful completion of the experiment. Firstly, a scale of bambara groundnut flower development was established based on flower size as a unit of measurement, from stage 8 to stage 13, which corresponds to floral organ differentiation and flower opening, respectively. Pollen architecture and development (micro-sporogenesis and micro-gametogenesis) was documented using fluorescence microscopy and SCM. And this study is the first one to link flower phenology to the stages of pollen development through morphological data. Secondly, the effect of short duration high temperature stress was evaluated, it showed that the effect on in vitro pollen germination was significant (p < 0.05) and was seen within 24 h of the application of the heat stress (HT-1) in all genotypes, and correspondingly pod set was significantly (p < 0.05) reduced during heat stress. The genotypes IITA-686, AHM-753 and S19-3 recovered, pollen viability relatively faster and produced pods when the plants were returned to control conditions after heat- stress, in contrast to Uniswa red and Getso, where pod set was severely affected. We could conclude that like most of the legumes bambara groundnut pollen is sensitive to high temperature stress, with temperatures 36/33°C producing significant effects on pollen viability, and also display acclimation capability, when returned to control conditions. We advocate that selection for breeding should start at male gamete level, through in vitro pollen germination to determine tolerant and sensitive genotypes, and the prospects of bambara groundnut pollen thermo-tolerance should be evaluated. Many research experts are considering bambara groundnut as a future crop based on its agro-ecological, cultural, genetic and nutritional importance. This research is one step in contributing to the knowledge of this future crop. This study serves as a guide for future researchers interested in flower development and variation in the process observed within and between bambara groundnut genotypes. Assessing pollen thermo-tolerance can give a direct indication of crop success/ seed yield under heat stress and the methodology is not limited to only temperature stress, that is it could also be adapted in photoperiod, drought and water stress. Investigation of other forms of stress tolerance could ultimately contribute to the development of future crop which could cope with future climatic anomalies.
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Roller, Patricia Suzanne 1968. "Distribution, growth, and reproduction of Pima pineapple cactus (Coryphantha scheeri Kuntz var robustispina Schott)." Thesis, The University of Arizona, 1996. http://hdl.handle.net/10150/278536.
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Pima pineapple cactus (Coryphantha scheeri var. robustispina) (PPC) is listed as endangered by the US Fish and Wildlife Service. This taxon occurs south of Tucson, Arizona and Sonora, Mexico. Knowledge of this plant's distribution, growth, and reproduction is important for management. Research has documented reduced plant vigor and lack of reproduction within Lehmann lovegrass stands. PPC density and seedling presence were described at five sites in two different vegetation types. Field observations of 72 plants at five sites were monitored from fall 1993 through summer of 95 and shadehouse studies were conducted. This research resulted in five conclusions: (1) fire-induced mortality of PPC may be related to Lehmann lovegrass, (2) PPC grows vegetatively in the spring, (3) flower buds are initiated in May and open after a few summer rains, (4) seed germination follows several summer rains, and (5) cross-pollination produces significantly more PPC seeds than self-pollination.
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Levy, Zuleika Antunes da Silva 1957. "EFFECTS OF A SYSTEMIC NEMATICIDE ON THE DEVELOPMENT AND REPRODUCTION OF MELOIDOGYNE INCOGNITA." Thesis, The University of Arizona, 1986. http://hdl.handle.net/10150/277114.
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Bray, Christopher James. "The effects of a plant compound, 6-MBOA, on reproduction in the wild rabbit Oryctolagus cuniculus (L.)." Thesis, University of Aberdeen, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.278785.
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This study tested the hypothesis that a plant compound, 6-methoxybenzoxazoline (6-MBOA), can affect the annual reproductive cycle of wild rabits by acting as an agonist or antagonist of melatonin. Preliminary investigations into seasonal changes in the reproductive endocrinology of wild-caught adult female rabbits kept in outdoor cages revealed an annual cycle of pituitary (release of LH) and ovarian (release of progesterone) responses to exogenous GnRH. The largest responses were between March and May (during the peak breeding season in the wild), followed by a decrease in July. Pituitary responsiveness returned by late November, whereas ovarian responsiveness did not increase until after the winter solstice. Studies of the responses to GnRH of adult female rabbits kept indoors under regulated photoperiod demonstrated that the decrease in pituitary and ovarian responsiveness in July was due to declining daylength. Seasonal regrowth of the reproductive system at the winter solstice was stimulated by transfer to `long days' (16L:8D). This stimulation by long days was not observed if rabbits were also treated with daily, timed intra-muscular (i.m.) injections of melatonin, but injections of 6-MBOA were ineffective. Daily, timed injections of 6-MBOA did not stimulate the reproductive system of seasonally-anoestrus adult female rabbits in the autumn. Treatment of adult female rabbits with sub-cutaneous (s.c.) implants of 6-MBOA failed to prevent a decrease in pituitary and ovarian responsiveness to GnRH on transfer to `short days' (8L:16D). Sexually mature male rabbits under long days received daily, timed i.m. injections of 6-MBOA or melatonin. Only those treated with melatonin showed testicular regression. A dose-response relationship for 6-MBOA was tested by treating adult male rabbits with 6-MBOA in different size s.c. implants. All sizes tested failed to induce testicular regression. No evidence was found that 6-MBOA can affect the annual reproductive cycle in wild rabbits by acting as an agonist or antagonist of melatonin.
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Klady, Rebecca A. "Long-term experimental warming effects on tundra plant sexual reproduction in the high Arctic." Thesis, University of British Columbia, 2006. http://hdl.handle.net/2429/31537.
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Predictions that climate warming will enhance plant sexual reproduction in the High
Arctic were examined using a field experiment at a polar oasis and a polar semi-desert
site in the eastern Canadian High Arctic. Small open top chambers (OTCs), which
simulated climate warming, were established in plant communities along a soil moisture
gradient in 1992. Over two growing seasons, fresh and over-wintered seeds across a
range of species were collected from aerial seed banks exposed to experimental warming
and ambient conditions. Seeds were weighed and germinated to measure changes in
reproductive effort and success in response to experimental warming. OTCs increased
within-plot growing season air temperatures by 1 - 2°C, which is within range of general
circulation model (GCM) predictions for climate warming in the Arctic. Reproductive
effort and success of fresh seeds were enhanced by warming in most species, depending
on initial site conditions. Enhanced reproductive effort and success may be attributed to
warming conditions, which advanced dates of snowmelt and extended the growing
season. Similar effects on over-wintered seeds were likely, but seed dispersal prior to
over-wintered seed harvests confounded these results. Inter-annual variability in
reproductive success appeared to be diminished by experimental warming. Further
testing will verify if this result is an indicator of long-term (> 10 y) warming effects.
Results of this study confirm predictions that long-term warming will enhance sexual
reproduction in high arctic plants. These changes will have implications for plant
demographics at the community-level and the rate and extent of bare-ground
colonization, particularly if rates of seedling establishment also increase.Arts, Faculty of
Geography, Department of
Graduate
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Gaol, Mangadas Lumban. "Ecological study of plant species at Sandford Rocks Nature Reserve (SRNR)." Thesis, Curtin University, 2002. http://hdl.handle.net/20.500.11937/234.
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The ecology of plant species at Sandford Rocks Nature Reserve (SRNR) was studied. The study site is an important nature reserve that contains relatively undisturbed natural vegetation. It has a mosaic of exposed granite rocks, scrublands and woodlands. The study involved: a description of the structure and composition of the vegetation; the population characteristics of selected Acacia species; aspects of reproduction in Acacia; germination and seedling characteristics of some Acacia and grass species that dominate the reserve; the effect of seed size on germination and seedling characteristics; and, the relationship of seed size to seed coat thickness in selected Acacia species. Five different areas were studied using the point centered quarter method to sample the woody perennial species. Thirteen Acacia species were examined for reproduction characteristics; and in 2 selected Acacia species, the effects of phyllode and/or inflorescence removal on reproduction was investigated. Germination tests were conducted to identify germination characteristics in 8 Acacia and 7 grass species dominant at SRNR. The possible effects of variation in seed size on germination; seedling characteristics; and, seed coat thickness were investigated in Acacia fauntleroyi and Acacia prainii. A total of 85 species from 20 families of woody perennials were collated. All areas were dominated by the Myrtaceae, Mimosaceae and Proteaceae families. There was considerable variability in the structure and composition of vegetation. Most species were present in particular sites and the composition of communities appears to be related to the heterogeneity of the habitat within the reserve. In areas of shallow or rocky soil, vegetation types present include Allocasuarina huegeliana woodland, Grevillea paradoxa low scrubland and Acacia neurophylla medium shrubland.In a seasonally wet area, vegetation types present include low open grassland; Eucalyptus capillosa (wandoo) woodland; and, Acacia saligna thicket. In deep, dry sandy soil, vegetation types include Phebalium tuberculosum shrubland, Acacia acuminata and Acacia coolgardiensis thickets. On relatively flat areas that gain water from adjacent large granite hills, the vegetation consists mainly of tall, open woodlands of Eucalyptus species. Vegetation types include: medium tall Eucalyptus salmonophloia woodland with Kunzea pulchella shrubland at the periphery of the Eucalyptus woodland. At rock areas, vegetation types present include dense Leptospermum erubescens thicket, low open Acacia prainii and Dodonaea viscosa shrubland. Of the Acacia populations studied, in A. lasiocalyx no recent seedling establishment was observed. It is hypothesised that recruitment occurs in particular periods. As the plants are associated with rock and soils are generally shallow, it appears that recruitment depends on run-off water from the rocks in winter. Continuous recruitment seems to be the pattern in A. prainii with both seedlings and saplings represented. A. fauntleroyi forms relatively small populations; apparently long drought periods (>l00 d) result in mass death and limit its population size. In A. hemiteles, no seedling stage was found, root competition (for water) from associated Eucalyptus species presumably limits its recruitment. Reproductive success of Acacia is affected by rainfall. A wet winter is required to induce flowering and further rain is required after flowering to promote pod development and good seed set.All Acacia species suffer from drought in the reproduction season, however they differ in their degree of susceptibility. Leaflessness and tree shape also affect Acacia fecundity. Plants bearing more phyllodes produce more flowers and pods, and branches in the upper part of the crown bear heavier inflorescences. In 1998, all Acacia species at SRNR produced mature seed of low weight, with many immature and diseased seed, which gave poor germination. A late spring frost in 1998 is believed to be responsible for limited seed development. In two selected Acacia species, removal of phyllodes reduced the number of pods produced. Presumably, phyllode removal reduces photosynthate produced, therefore the competition among inflorescences (or pods) for resources is more intense and subsequent abortions are likely to occur. All Acacia species studied showed best germination in the cool winter temperature range. Apparently, seeds are adapted to germinate in winter when seasonal moisture is more likely to be available. The best temperature however, varied slightly between species. The grass species dominant in the reserve, except for Aristida contorta, also had more germination in cooler rather than warmer temperatures. The flora of SRNR is similar to typical vegetation of the Southwest. Generally, Acacia species are present only in particular sites, presumably were habitat moisture allows. Seedlings of Acacia species growing in naturally dry areas have greater root: shoot masses than those growing in seasonally wet areas. Biomass partitioning is an apparent strategy to conserve water. Of the 7 grass species, Amphipogon strictus appears to have fastest growth.Eriachne ovata has greater root than shoot mass, while in all other species, shoot mass is greater than root mass; a characteristic of species that grow well in moist habitats. The longest shoots and roots are in Austrostipa elegantissima, an understorey species of eucalypt woodland. In A. fauntleroyi, the degree of hard-seededness varies between seed sizes. There is a higher proportion of soft seed in smaller seed. Seed of different sizes show some responses to different pre-treatments and incubation temperatures for germination. Larger seeds generally germinate in greater numbers after higher treatment temperatures. The best treatment for small seeds is pre-treatment at 75°C and incubated at 15°C. For medium and large seed, best pre-treatment is at 75°C with incubation at 30°C or soaking in boiling water and incubation at either 15 or 3°C. In A. prainii, seed size; pre-treatment; incubation; and, their interaction all affected germination; larger seeds are more viable. The best treatment to promote germination of A. prainii is soaking in boiling water and incubation at 25°C. In both A. fauntleroyi and A. prainii, larger seeds produce larger seedlings. Seedlings from large seeds have the potential for more rapid pre-photosynthetic growth. Larger, heavier seed has a thicker seed coat. The seed coat of A. prainii is thicker than in A. fauntleroyi; the difference in seed coat thickness is reflected by more soft seed in A. fauntleroyi (35%) than in A. prainii (6%).
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Docking, T. Roderick. "The evolution of retrotransposon sequences in four asexual plant species /." Thesis, McGill University, 2004. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=81327.
Full textAbstract:
Since their discovery, transposable elements (TEs) have been regarded either as useful building blocks of genomes, or as "selfish DNA": genetic parasites that exploit the sexual cycle to spread in copy number within populations to the detriment of their hosts. If the "selfish DNA" hypothesis is correct, TEs are expected to deteriorate and be lost from asexual populations. This thesis tests the predictions of the "selfish DNA" hypothesis in four asexual plant species, focusing on patterns of nucleotide diversity and nucleotide substitution. Sequences bearing strong resemblance to known TE families including Ty1/copia, Ty3/gypsy, and LINE-like elements were successfully isolated from all four plant species, and showed patterns of nucleotide substitution consistent with a long history of purifying selection. Stochastic simulations were also conducted, and suggested that this result is expected if the host species has been asexual for less than tens of thousands of generations.
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Haig, David. "Applications of allocation and kinship models to the interpretation of vascular plant life cycles." Phd thesis, Australia : Macquarie University, 1990. http://hdl.handle.net/1959.14/23227.
Full textAbstract:
Thesis by publication.Thesis (PhD) -- Macquarie University, School of Biological Sciences, 1990.
Bibliography: leaves 269-324.
Introduction -- Models of parental allocation -- Sex expression in homosporous pteridophytes -- The origin of heterospory -- Pollination and the origin of the seed habit -- Brood reduction in gymnosperms -- Pollination: costs and consequences -- Adaptive explanations for the rise of the angiosperms -- Parent-specific gene expression and the triploid endosperm -- New perspectives on the angiosperm female gametophyte -- Overview -- Glossary -- Kinship terms in plants -- Literature Cited.
Among vascular plants/ different life cycles are associated with characteristic ranges of propagule size. In the modern flora, isospores of homosporous pteridophytes are almost all smaller than 150 urn diameter, megaspores of heterosporous pteridophytes fall in the range 100-1000 urn diameter, gymnosperm seeds are possibly all larger than the largest megaspores, but the smallest angiosperm seeds are of comparable size to large isospores. -- Propagule size is one of the most important features of a sporophyte's reproductive strategy. Roughly speaking, larger propagules have larger food reserves, and a greater probability of successful establishment, than smaller propagules, but a sporophyte can produce more smaller propagules from the same quantity of resources. Different species have adopted very different size-versus-number compromises. The characteristic ranges of propagule size, in each of the major groups of vascular plants, suggest that some life cycles are incompatible with particular size-versus-number compromises. -- Sex expression in homosporous plants is a property of gametophytes (homosporous sporophytes are essentially asexual). Gametophytes should produce either eggs or sperm depending on which course of action gives the greatest chance of reproductive success. A maternal gametophyte must contribute much greater resources to a young sporophyte than the paternal gametophyte. Therefore, smaller gametophytes should tend to reproduce as males, and gametophytes with abundant resources should tend to reproduce as females. Consistent with these predictions, large female gametophytes release substances (antheridiogens) which induce smaller neighbouring ametophytes to produce sperm. -- The mechanism of sex determination in heterosporous species appears to be fundamentally different. Large megaspores develop into female gametophytes, and small icrospores develop into male gametophytes. Sex expression appears to be determined by the sporophyte generation. This is misleading. As argued above, the optimal sex expression of a homosporous gametophyte is influenced by its access to resources. This is determined by (1) the quantity of food reserves in its spore and (2) the quantity of resources accumulated by the gametophyte's own activities. If a sporophyte produced spores of two sizes, gametophytes developing from the larger spores' would be more likely to reproduce as females than gametophytes developing from the smaller spores, because the pre-existing mechanisms of sex determination would favor production of archegonia by larger gametophytes. Thus, the predicted mechanisms of sex determination in homosporous species could also explain the differences in sex expression of gametophytes developing from large and small spores in heterosporous species.
Megaspores of living heterosporous pteridophytes contain sufficient resources for female reproduction without photosynthesis by the gametophyte (Platyzoma excepted), whereas microspores only contain sufficient resources for male reproduction. Furthermore, many more microspores are produced than megaspores. A gametophyte's optimal sex expression is overwhelmingly determined by the amount of resources supplied in its spore by the sporophyte, and is little influenced by the particular environmental conditions where the spore lands. Gametophytes determine sex expression in heterosporous species, as well as homosporous species. A satisfactory model for the evolution of heterospory needs to explain under what circumstances sporophytes will benefit from producing spores of two distinct sizes. -- In Chapter 4, I present a model for the origin of heterospory that predicts the existence of a "heterospory threshold". For propagule sizes below the threshold, homosporous reproduction is evolutionarily stable because gametophytes must rely on their own activities to accumulate sufficient resources for successful female reproduction. Whether a gametophyte can accumulate sufficient resources before its competitors is strongly influenced by environmental conditions. Gametophytes benefit from being able to adjust their sex expression in response to these conditions. For propagule sizes above the threshold, homosporous reproduction is evolutionarily unstable, because the propagule's food reserves are more than sufficient for a "male" gametophyte to fertilize all eggs within its neighbourhood. A population of homosporous sporophytes can be invaded by sporophytes that produce a greater number of smaller spores which could land in additional locations and fertilize additional eggs. Such'spores would be male-specialists on account of their size. Therefore, both spore types would be maintained in the population because of frequency-dependent selection. -- The earliest vascular plants were homosporous. Several homosporous groups gave rise to heterosporous lineages, at least one of which was the progeniture of the seed plants. The first heterosporous species appear in the Devonian. During the Devonian, there was a gradual increase in maximum spore size, possibly associated with the evolution of trees and the appearance of the first forests. As the heterospory threshold was approached, the optimal spore size for female reproduction diverged from the optimal spore size for male reproduction. Below the threshold, a compromise spore size gave the highest fitness returns to sporophytes, but above the threshold, sporophytes could attain higher fitness by producing two types of spores. -- The evolution of heterospory had profound consequences. Once a sporophyte produced two types of spores, microspores and megaspores could become specialized for male and female function respectively. The most successful heterosporous lineage (or lineages) is that of the seed plants. The feature that distinguishes seed plants from other heterosporous lineages is pollination, the capture of microspores before, rather than after, propagule dispersal. Traditionally, pollination has been considered to be a major adaptive advance because it frees sexual reproduction from dependence on external fertilization by freeswimming sperm, but pollination has a more important advantage. In heterosporous pteridophytes, a megaspore is provisioned whether or not it will be fertilized whereas seeds are only provisioned if they are pollinated.
The total cost per seed cannot be assessed solely from the seed's energy and nutrient content. Rather, each seed also has an associated supplementary cost of adaptations for pollen capture and of resources committed to ovules that remain unpollinated. The supplementary cost per seed has important consequences for understanding reproductive strategies. First, supplementary costs are expected to be proportionally greater for smaller seeds. Thus, the benefits of decreasing seed size (in order to produce more seeds) are reduced for species with small seeds. This effect may explain minimum seed sizes. Second, supplementary costs are greater for populations at lower density. Thus, there is a minimum density below which a species cannot maintain its numbers. -- By far the most successful group of seed plants in the modern flora are the angiosperms. Two types of evidence suggest that early angiosperms had a lower supplementary cost per seed than contemporary gymnosperms. First, the minimum size of angiosperm seeds was much smaller than the minimum size of gymnosperm seeds. This suggests that angiosperms could produce small seeds more cheaply than could gymnosperms. Second, angiosperm-dominated floras were more speciose than the gymnosperm-dominated floras they replaced. This suggests that the supplementary cost per seed of angiosperms does not increase as rapidly as that of gymnosperms, as population density decreases. In consequence, angiosperms were able to displace gymnosperms from many habitats, because the angiosperms had a lower cost of rarity. -- Angiosperm embryology has a number of distinctive features that may be related to the group's success. In gymnosperms, the nutrient storage tissue of the seed is the female gametophyte. In most angiosperms, this role is taken by the endosperm. Endosperm is initiated by the fertilization of two female gametophyte nuclei by a second sperm that is genetically identical to the sperm which fertilizes the egg. Endosperm has identical genes to its associated embryo, except that there are two copies of maternal genes for every copy of a paternal gene. -- Chapter 9 presents a hypothesis to explain the unusual genetic constitution of endosperm. Paternal genes benefit from their endosperm receiving more resources than the amount which maximizes the fitness of maternal genes, and this conflict is expressed as parent-specific gene expression in endosperm. The effect of the second maternal genome is to increase maternal control of nutrient acquisition. -- Female gametophytes of angiosperms are traditionally classified as monosporic, bisporic or tetrasporic. Bisporic and tetrasporic embryo sacs contain the derivatives of more than one megaspore nucleus. Therefore, there is potential for conflict between the different nuclear types within an embryo sac, but this possibility has not been recognized by plant embryologists. In Chapter 10, I show that many previously inexplicable observations can be understood in terms of genetic conflicts within the embryo sac.
Mode of access: World Wide Web.
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Taylor, Robin M. "Plant nectar contributes to the survival, activity, growth, and fecundity of the nectar-feeding wandering spider Cheiracanthium inclusum (Hentz) (Miturgidae)." Columbus, Ohio : Ohio State University, 2004. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1086114717.
Full textAbstract:
Thesis (Ph. D.)--Ohio State University, 2004.Title from first page of PDF file. Document formatted into pages; contains xii, 138 p.; also includes graphics. Includes abstract and vita. Advisor: Richard A. Bradley, Dept. of Evolution, Ecology, and Organismal Biology. Includes bibliographical references (p. 124-138).
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Napier, James Alexander. "Variation and adaptation in Allium ursinum L." Thesis, University of Ulster, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.242062.
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Soares, Natalia Costa. "Variação intra-específica na fenologia de espécies de sub-bosque de floresta Atlântica e sua relação com variáveis microambientais /." Rio Claro : [s.n.], 2011. http://hdl.handle.net/11449/87852.
Full textAbstract:
Orientador: L. Patricia C. MorellatoBanca: Flavio Nunes Ramos
Banca: Sergius Gandolfi
Resumo: Variação intra-específica na fenologia de espécies de sub-bosque de Floresta Atlântica e sua relação com variáveis microambientais - Fatores abióticos, como a umidade relativa, temperatura e luz, influenciam o estabelecimento, desenvolvimento e reprodução das espécies vegetais florestais. Entretanto é necessária a coleta de parâmetros estruturais, microclimáticos e microambientais para a caracterização dos ambientes nos quais as plantas se desenvolvem. Neste contexto, o presente trabalho objetivou avaliar a influência de fatores do microambiente na resposta fenológica de espécies vegetais componentes do sub-bosque de floresta Atlântica, em Ubatuba, SP. Procuramos responder as seguintes perguntas: i) As plantas de sub-bosque podem ser agrupadas em relação aos ambientes de luz: borda natural, clareira e interior sombreado da floresta?; ii) Existem variações intra-específicas na fenologia das espécies de sub-bosque de Floresta Atlântica de acordo com o ambiente de luz em que foram agrupadas?; iii) A intensidade das respostas fenológicas (número de estruturas reprodutivas produzidas) está relacionada aos locais de luz?; iv) Outras condições microclimáticas, como temperatura e umidade relativa, e microambientais, como a densidade da vegetação, também influenciam a fenologia das espécies? Para tanto a fenologia e a produção de estruturas reprodutivas de quatro espécies abundantes do sub-bosque foram acompanhadas de janeiro de 2009 a abril de 2010. Indivíduos foram selecionados em ambientes previamente determinados como borda natural (beira de rio), clareira e interior de floresta atlântica. Medidas periódicas das variáveis microclimáticas (temperatura, umidade relativa, PAR) e microambiental (abertura do dossel) próximas aos indivíduos amostrados foram realizadas. Medidas estruturais... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Phenological intraspecific variation of Atlantic Forest understory species and its relation to microenvironmental variables - Abiotic factors such as humidity, temperature and light influence the establishment, development and reproduction of forest plant species. However, it is necessary to collect structural, microclimatic and microenvironmental parameters to characterize the environments in which plants grow. In this context, this study evaluated the influence of the microenvironment in the phenological response of understory plant species components of the Atlantic Forest in Ubatuba, São Paulo State. We tried to answer the following questions: i) Can the understory species be grouped in relation to natural edge, gaps and interior microenvironments? ii) Do exist intraspecific variations in the phenology of understory species of Atlantic forest in accordance with the light environment in which they were grouped? iii) Do the intensity of phenological responses (number of reproductive structures produced) related to local condictions of light?; iv) Do other microclimatic (such as temperature and relative humidity) and microenvironmental (density vegetation) conditions also influence the phenology of species? The phenology and reproductive structures production of four abundant species of the understory were followed from January 2009 to April 2010. Individuals were selected in environments previously determined as natural edge (riverside), gap and interior. We performed periodic measurements of microclimatic (temperature, relative humidity and PAR) and microenvironmental variables (canopy openness) near the sampled individuals. Structural measures (CAS, CAP, plant height, crown height from the ground and crown size) and microenvironment characterization (canopy height, understory vertical density, distance... (Complete abstract click electronic access below)
Mestre
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Sampson, Dennis Archie. "An assessment of the evolutionary stability of distyly in Hedyotis caerulea (Rubiaceae)." Cleveland State University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=csu1296756691.
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Bolmgren, Kjell. "Adaptation and Constraint in the Plant Reproductive Phase." Doctoral thesis, Stockholm : Botaniska institutionen, Univ, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-99.
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Gaol, Mangadas Lumban. "Ecological study of plant species at Sandford Rocks Nature Reserve (SRNR)." Curtin University of Technology, Department of Environmental Biology, 2002. http://espace.library.curtin.edu.au:80/R/?func=dbin-jump-full&object_id=13955.
Full textAbstract:
The ecology of plant species at Sandford Rocks Nature Reserve (SRNR) was studied. The study site is an important nature reserve that contains relatively undisturbed natural vegetation. It has a mosaic of exposed granite rocks, scrublands and woodlands. The study involved: a description of the structure and composition of the vegetation; the population characteristics of selected Acacia species; aspects of reproduction in Acacia; germination and seedling characteristics of some Acacia and grass species that dominate the reserve; the effect of seed size on germination and seedling characteristics; and, the relationship of seed size to seed coat thickness in selected Acacia species. Five different areas were studied using the point centered quarter method to sample the woody perennial species. Thirteen Acacia species were examined for reproduction characteristics; and in 2 selected Acacia species, the effects of phyllode and/or inflorescence removal on reproduction was investigated. Germination tests were conducted to identify germination characteristics in 8 Acacia and 7 grass species dominant at SRNR. The possible effects of variation in seed size on germination; seedling characteristics; and, seed coat thickness were investigated in Acacia fauntleroyi and Acacia prainii. A total of 85 species from 20 families of woody perennials were collated. All areas were dominated by the Myrtaceae, Mimosaceae and Proteaceae families. There was considerable variability in the structure and composition of vegetation. Most species were present in particular sites and the composition of communities appears to be related to the heterogeneity of the habitat within the reserve. In areas of shallow or rocky soil, vegetation types present include Allocasuarina huegeliana woodland, Grevillea paradoxa low scrubland and Acacia neurophylla medium shrubland.In a seasonally wet area, vegetation types present include low open grassland; Eucalyptus capillosa (wandoo) woodland; and, Acacia saligna thicket. In deep, dry sandy soil, vegetation types include Phebalium tuberculosum shrubland, Acacia acuminata and Acacia coolgardiensis thickets. On relatively flat areas that gain water from adjacent large granite hills, the vegetation consists mainly of tall, open woodlands of Eucalyptus species. Vegetation types include: medium tall Eucalyptus salmonophloia woodland with Kunzea pulchella shrubland at the periphery of the Eucalyptus woodland. At rock areas, vegetation types present include dense Leptospermum erubescens thicket, low open Acacia prainii and Dodonaea viscosa shrubland. Of the Acacia populations studied, in A. lasiocalyx no recent seedling establishment was observed. It is hypothesised that recruitment occurs in particular periods. As the plants are associated with rock and soils are generally shallow, it appears that recruitment depends on run-off water from the rocks in winter. Continuous recruitment seems to be the pattern in A. prainii with both seedlings and saplings represented. A. fauntleroyi forms relatively small populations; apparently long drought periods (>l00 d) result in mass death and limit its population size. In A. hemiteles, no seedling stage was found, root competition (for water) from associated Eucalyptus species presumably limits its recruitment. Reproductive success of Acacia is affected by rainfall. A wet winter is required to induce flowering and further rain is required after flowering to promote pod development and good seed set.
All Acacia species suffer from drought in the reproduction season, however they differ in their degree of susceptibility. Leaflessness and tree shape also affect Acacia fecundity. Plants bearing more phyllodes produce more flowers and pods, and branches in the upper part of the crown bear heavier inflorescences. In 1998, all Acacia species at SRNR produced mature seed of low weight, with many immature and diseased seed, which gave poor germination. A late spring frost in 1998 is believed to be responsible for limited seed development. In two selected Acacia species, removal of phyllodes reduced the number of pods produced. Presumably, phyllode removal reduces photosynthate produced, therefore the competition among inflorescences (or pods) for resources is more intense and subsequent abortions are likely to occur. All Acacia species studied showed best germination in the cool winter temperature range. Apparently, seeds are adapted to germinate in winter when seasonal moisture is more likely to be available. The best temperature however, varied slightly between species. The grass species dominant in the reserve, except for Aristida contorta, also had more germination in cooler rather than warmer temperatures. The flora of SRNR is similar to typical vegetation of the Southwest. Generally, Acacia species are present only in particular sites, presumably were habitat moisture allows. Seedlings of Acacia species growing in naturally dry areas have greater root: shoot masses than those growing in seasonally wet areas. Biomass partitioning is an apparent strategy to conserve water. Of the 7 grass species, Amphipogon strictus appears to have fastest growth.
Eriachne ovata has greater root than shoot mass, while in all other species, shoot mass is greater than root mass; a characteristic of species that grow well in moist habitats. The longest shoots and roots are in Austrostipa elegantissima, an understorey species of eucalypt woodland. In A. fauntleroyi, the degree of hard-seededness varies between seed sizes. There is a higher proportion of soft seed in smaller seed. Seed of different sizes show some responses to different pre-treatments and incubation temperatures for germination. Larger seeds generally germinate in greater numbers after higher treatment temperatures. The best treatment for small seeds is pre-treatment at 75°C and incubated at 15°C. For medium and large seed, best pre-treatment is at 75°C with incubation at 30°C or soaking in boiling water and incubation at either 15 or 3°C. In A. prainii, seed size; pre-treatment; incubation; and, their interaction all affected germination; larger seeds are more viable. The best treatment to promote germination of A. prainii is soaking in boiling water and incubation at 25°C. In both A. fauntleroyi and A. prainii, larger seeds produce larger seedlings. Seedlings from large seeds have the potential for more rapid pre-photosynthetic growth. Larger, heavier seed has a thicker seed coat. The seed coat of A. prainii is thicker than in A. fauntleroyi; the difference in seed coat thickness is reflected by more soft seed in A. fauntleroyi (35%) than in A. prainii (6%).
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Thompson, Faye Laura. "Somatic, genetic and evolutionary trade-offs between sexual and asexual reproduction in a clonal aquatic plant." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2002. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/MQ65650.pdf.
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Genau, Anne Christina [Verfasser], and Stefan A. [Akademischer Betreuer] Rensing. "Evolutionary conservation of epigenetic control of plant sexual reproduction / Anne Christina Genau ; Betreuer: Stefan A. Rensing." Marburg : Philipps-Universität Marburg, 2021. http://d-nb.info/122758010X/34.
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Zidko, Alexsandro. "Coleópteros (insecta) associados às estruturas reprodutivas de espécies florestais arbóreas nativas no Estado de São Paulo." Universidade de São Paulo, 2002. http://www.teses.usp.br/teses/disponiveis/11/11150/tde-16072002-143506/.
Full textAbstract:
As espécies florestais arbóreas nativas apresentam interações com coleópteros que se desenvolvem no interior das estruturas reprodutivas. Foram estudadas as seguintes espécies florestais arbóreas nativas e identificados os coleópteros a elas associados: Pterogyne nitens Tul. (amendoim-bravo) - Tricorynus sp. (Anobiidae) e Ormiscus sp. (Anthribidae); Stryphnodendron adstringens (Mart.) Cov. (barbatimão) - Acanthoscelides sp. (Bruchidae); Cassia grandis L. f. (cássia-grande) - Pygiopachymerus lineola (Bruchidae); Tabebuia alba (Cham.) Sandwith (ipê-amarelo) - Sitophilus linearis (Curculionidae); Hymenaea courbaril var. stilbocarpa (Hayne) Lee & Lang (jatobá) - Tricorynus sp. (Anobiidae); Chorisia speciosa (A. St. - Hil.) Dawson (paineira) - Lonchophorus obliquus (Curculionidae); Caesalpinia ferrea var. leiostachya Benth. (pau-ferro) - Pityophthorus sp. (Scolytidae); Aspidosperma polyneuron Müll. Arg (peroba) - Tricorynus sp. (Anobiidae) e Rhinochoenus stigma (Curculionidae); Enterolobium contortisiliquum (Vell.) Morong (timbó) - Stator pacarae(Bruchidae).This paper deals with the identification of Coleoptera (species and family) associated to the reproductive structures of the following native forest tree species: Pterogyne nitens Tul. ("amendoim-bravo") - Tricorynus sp. (Anobiidae) and Ormiscus sp. (Anthribidae); Stryphnodendron adstringens (Mart.) Cov.("barbatimão") - Acanthoscelides sp. (Bruchidae); Cassia grandis L. f. ("cássiagrande") - Pygiopachymerus lineola (Bruchidae); Tabebuia alba (Cham.) Sandwith ("ipê-amarelo") - Sitophilus linearis (Curculionidae); Hymenaea courbaril var. stilbocarpa (Hayne) Lee & Lang ("jatobá") - Tricorynus sp. (Anobiidae); Chorisia speciosa (A. St. - Hil.) Dawson ("paineira") - Lonchophorus obliquus (Curculionidae); Caesalpinia ferrea var. leiostachya Benth. ("pau-ferro") - Pityophthorus sp. (Scolytidae); Aspidosperma polyneuron Müll. Arg ("peroba") - Tricorynus sp. (Anobiidae) and Rhinochoenus stigma(Curculionidae); Enterolobium contortisiliquum (Vell.) Morong ("timbó") - Stator pacarae (Bruchidae).
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Tan, Lor-Wai. "Biochemical aspects of self-incompatibility in Petunia hybrida." Title page, Contents and Summary only, 1988. http://web4.library.adelaide.edu.au/theses/09A/09at161.pdf.
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Nicholls, Ann M. "Influences of Environmental Variability, Genetics and Plant Size on Variation in Sexual and Clonal Reproduction and Allocation of Resources in Three Wetland Plant Species." Cleveland State University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=csu1305559126.
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Siekmann, Gitta. "Food foraging in adult parasitoid Cotesia rubecula : how sugar sources contribute to survival and reproduction." Title page, contents and abstract only, 2002. http://web4.library.adelaide.edu.au/theses/09PH/09phs5715.pdf.
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Bibliography: leaves 133-148. Examines sugar foraging in the field by adult female parasitoid wasp, Cotesia rubecula (Hymenoptera, Braconidae), to determine its effect on fecundity and lifespan. In the field, the area in which wasps search for sugar is likely to depend on the degree of association of hosts with nectar or honeydew, supporting the hypothesis that sugar encounters in the field happen opportunistically during host foraging activities. The survival gained by sugar feeding my often be severely limited by quality and quantity of sugary food and extrinsic mortality factors such as adverse weather conditions and predation, so the need for food must be studied in relation to a species' adaptation to its environment. Concentrations of sugar sources may distract wasps from host-foraging when the density of hosts is low. This has implications for flower propagation in agro-ecosystems with a view to supporting natural enemies of insect pests.
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Houghteling, Billy Burr. "Isolation of differentially expressed messages in sexually reproducing tripsacum dactyloides." Virtual Press, 1998. http://liblink.bsu.edu/uhtbin/catkey/1074547.
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The isolation and characterization of the gene(s) associated with and potentially responsible for the regulation of apomixis (asexual) and sexual reproduction in the grass species Tripsacum dactyloides is quintessential to agricultural advancement. Apomixis is the mechanism by which plants can produce seed without fertilization, where all progeny are genetically identical to the maternal parent. In natural populations of the genus Tripsacum, lower ploidy forms (i.e., diploid, 2n=36) reproduce sexually and the higher ploidy forms (triploid, 3n=54; tetraploid, 4n=72; etc.) reproduce asexually via apomixis. In order to gain a better understanding of sexual reproductive processes in plants, subtractive hybridization was performed on early and late female inflorescence gene products. This procedure allows for the recovery of gene products in the form of complimentary DNA, cDNA molecules, which correspond to messenger RNA (mRNA) present. These cDNA molecules were then used to extract unique sequence messages from the early developmental stage ovule tissue of diploid T. dactyloides. These cDNA molecules will allow for the direct isolation of the original form of the gene(s) from a large fragment library of the Tripsacum genome. Isolation and characterization of these gene(s) is of pivotal importance to our understanding of alternate modes of reproduction in Tripsacum.Department of Biology
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Bowman, G. Brian. "A comparison of vascular, herbaceous plants between disturbed and undisturbed east-central Indiana woodlots." Virtual Press, 1995. http://liblink.bsu.edu/uhtbin/catkey/941351.
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The mode of propagation of a plant species may influence its success in recolonizing a successional forest following agricultural disturbance. It is hypothesized that plants with animal-borne or broadcast-dispersed seed will successfully recolonize, while plants which rely upon vegetative propagules may not repopulate the disturbed area. This hypothesis was tested by comparing vascular, herbaceous plant communities of two forests (one old-growth and one successional) in east-central Indiana. Populations of vascular, herbaceous plant species were inventoried in both forests, and the soil characteristics (organic matter and pH) of both areas were analyzed. The two forests had similar soil organic matter profiles, but the pH of the disturbed forest was significantly lower than that of the undisturbed area. Most vegetatively-propagated plant species were, as predicted, significantly more abundant in the undisturbed forest; the disturbed area had been effectively recolonized by animal-borne and broadcast-dispersed seed plants. This perspective has implications for long-term management of east-central Indiana forests.Department of Natural Resources and Environmental Management
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Lopez, Swalls Renee Anita. "THE SPECIAL WALLS AROUND GAMETES IN CERATOPTERIS RICHARDII AND AULACOMNIUM PALUSTRE: USING IMMUNOCYTOCHEMISTRY TO EXPOSE STRUCTURE, FUNCTION, AND DEVELOPMENT." OpenSIUC, 2016. https://opensiuc.lib.siu.edu/dissertations/1257.
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AN ABSTRACT OF THE DISSERTATION OF RENEE A LOPEZ SWALLS, for the Doctor of Philosophy degree in PLANT BIOLOGY, presented on June 27, 2016, at Southern Illinois University Carbondale. TITLE: THE SPECIAL WALLS AROUND GAMETES IN CERATOPTERIS RICHARDII AND AULACOMNIUM PALUSTRE: USING IMMUNOCYTOCHEMISTRY TO EXPOSE STRUCTURE, FUNCTION, AND DEVELOPMENT MAJOR PROFESSOR: Dr. Karen S. Renzaglia Gametes are arguably the most important cells formed during the sexual life cycle of plants. The ancestral condition of gametes in land plants is the production of small motile sperm cells and larger non-motile eggs. Unique walls or cell matrices are formed during the development of these highly specialized cells, and are integral to their proper development and maturation. Yet, the polysaccharide composition, structural function, and metabolic processes of these special gamete cell walls remain unexplored beyond examination in the light microscope. Utilizing histochemical techniques coupled with immunocytochemical localizations with monoclonal antibodies (MAbs), I give a detailed survey of AGP and cell wall polymer distribution during male and female gametogenesis in the model fern, Ceratopteris richardi, and for comparison with both Ceratopteris and seed plants, I examined the same cell wall polymers during spermatogenesis in Aulacomnium palustre, a moss species. AGPs are abundant in the extraprotoplasmic matrix that surrounds differentiating sperm and egg cells in the fern, Ceratopteris richardii. During spermatogenesis, AGPs are speculated to regulate growth of flagella and cell morphogenesis through cell signaling via Ca+2 oscillations. Immunogold localizations revealed that AGPs are differentially expressed in the egg envelope in C. richardii. These glycoproteins are extremely abundant prior to fertilization but decrease substantially after fusion of the male gamete with the egg cytoplasm. Contrary to the AGP-filled matrix surrounding developing spermatids, developing eggs are bathed in (1,5)-α-L-arabinan pectins and not AGPs. Lastly, I examined the unique cell walls that are integral to sperm cell differentiation and release in both Ceratopteris and Aulacomnium. The preponderance of callose and hemicelluloses in the walls of the male gametes of Ceratopteris and Aulacomnium, respectively, and the importance of these polysaccharides in development are discussed. Taken together, the studies that comprise this dissertation advance significantly our understanding of cell wall dynamics during gametogenesis in early land plants.
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Shortlidge, Erin Elizabeth. "Testing the Ecological and Physiological Factors Influencing Reproductive Success in Mosses." PDXScholar, 2014. http://pdxscholar.library.pdx.edu/open_access_etds/1951.
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As non-vascular, early land plants with an aquatic ancestry, mosses do not regulate internal water conditions separate from that of their environment and as a result, evolved mechanisms to survive in a terrestrial world out of water. Yet, there is a widely accepted dogma that moss reproductive success is solely dependent on rainfall events carrying swimming, bi-flagellate sperm across the landscape to reproductively mature and receptive female mosses--but this classic view of moss reproduction may be too simplistic. In this dissertation I test the assumptions of reproductive limitation in mosses and present novel findings in a basal, yet understudied terrestrial plant mating system.
I find evidence of environmental desiccation tolerance in moss sperm, thus offering the potential for stress-tolerant gametes on the landscape possibly suited for various transport vectors, reminiscent of a pollen grain. To investigate the broad evolutionary implications of this newfound complexity in moss sexual reproduction, I tested classic tenets of plant-pollinator theory on the ancient mosses and their ubiquitous microarthropod inhabitants. Experimental results show that mosses and microarthropods are engaged in a "pollination-like" syndrome guided by sex-specific volatile cues that differentially affect microarthropod behavior. These data indicate an existing complex mutualistic relationship and provides new evidence of sexually dimorphic investment by male and female mosses into reproductive success. Further, these data put forth the idea that female mosses challenge an inherent mate limitation by investing into reproductive assurance via maintaining a relationship with microarthropods.
Experimental work further confirms a role for invertebrates in moss reproductive success and tests mutualism theory through ongoing experiments. Such experiments include an assessment of moss genetic diversity, paternity, and male fitness traits as it relates to mosses with or without the presence of microarthropods, thereby testing for fitness benefits gained by mosses possibly engaged in a transport mutualism with microarthropods.
I further tested mutualism, community ecology and moss sexual reproduction concepts in extreme geothermal moss populations living at the edges of inhabitable Earth, and results show that even geothermal moss canopies are diverse and host differential and abundant life. In a first field test of mutualism I found that although extreme heat stress may constrain sexual reproduction in mosses, a correlation between within-population moss genetic diversity and microarthropod abundances exists. To further examine mosses in extreme environments, and how these environments may constrain sexual reproductive success, I evaluated the effects of simulated warming on Antarctic moss physiology and reproductive biology. Data indicates that simulated warming relieves mosses of physiological stress, and results in a greater investment into primary productivity and sexual reproduction. These data support the hypothesis that with less stress, sexual reproduction is increased. Mosses are an ideal system by which to understand organisms that exist in environments ranging from the mesic to the extreme, in the laboratory and the field and even in the classroom, where the small functioning ecosystem of mosses can be used for discovery-based biology education as described in the Mosscosms curriculum.
This work contributes significantly to the field of bryophyte and plant biology by revealing novel insights into the biotic and abiotic drivers of sexual reproduction in mosses.
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Metzger, Genevieve. "CLONALITY AND GENETIC DIVERSITY IN POLYGONELLA MYRIOPHYLLA, A LAKE WALES RIDGE ENDEMIC PLANT." Master's thesis, University of Central Florida, 2010. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2103.
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Although capable of sexual reproduction, many plants also rely heavily on clonal reproduction. The formation of multiple, physiologically-independent units with the same genotype has important implications for spatial genetic structure and genetic diversity in these plants. The endangered scrub-dwelling perennial, Polygonella myriophylla is known to reproduce both sexually and clonally but no study to date has been able to investigate the spatial genetic patterns that occur in this species. I use microsatellite markers to investigate questions about clonal structure and genetic diversity in five populations of P. myriophylla and address some of the implications of my findings for conservation of this species: Overall, I find that 57% of sampled clusters of P. myriophylla are composed of a single genet (genetic individual) with multiple physiological units (ramets) while the remainder are made up of two or more genets. I found differences in both clonal reproduction and genetic diversity among populations. I also found evidence of limited gene flow even over small spatial scales (less than 10 km) and for at least 4 genetic clusters occurring within the species range. Despite high levels of genetic diversity overall, there is evidence of reduced genetic diversity in two populations My results suggest that high levels of clonality may be important in maintaining genetic diversity in P. myriophylla. I also provide evidence that dirt roadsides may not represent a refuge for this species.M.S.
Department of Biology
Sciences
Biology MS
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Hart, Rodney S. (Rodney Sebastian). "Physical interactions of filamentous fungal spores and unicellular fungi." Thesis, Stellenbosch : University of Stellenbosch, 2006. http://hdl.handle.net/10019.1/17371.
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Thesis (MSc)--University of Stellenbosch, 2006.ENGLISH ABSTRACT: It is known that many hyphomycetous fungi are dispersed by wind, water and insects. However, very little is known about how these fungi may differ from each other regarding their ability to be disseminated by different environmental vectors. Consequently, to obtain an indication of the primary means of spore dispersal employed by representatives of the genera Acremonium, Aspergillus and Penicillium, isolated from soil and indoor environments, we monitored spore liberation of cultures representing these genera in an airflow cell. The experimental data obtained, of plate counts conducted of the air at the outlet of the airflow cell, were subjected to an appropriate analysis of variance (ANOVA), using SAS statistical software. Intraspecific differences occurred regarding aerial spore release. Under humid conditions, however, Penicillium species were more successful in releasing their spores than Aspergillus and the Acremonium strain. Under desiccated conditions the Aspergillus took longer to release their spores than representatives of Acremonium and Penicillium. The taxa that were investigated did not differ from each other regarding the release of spores in physiological salt solution (PSS). Although not proven, indications are that water may act as an important dispersion agent for these fungi, because washing of cultures with PSS resulted in all cases in an immediate massive release of colony forming units. Subsequently, using standard plate count techniques, conidial adhesion of the fungi mentioned above to synthetic membranes, leaf cuttings and insect exoskeletons differing in hydrophobicity and electrostatic charge were investigated. We found that the different genera showed different adhesion profiles for the series of test surfaces, indicating differences in physico-chemical characteristics of the fungal spore surfaces. In general, the Penicillium strains showed a greater ability to adhere to the test surfaces, than the aspergilli, while the representative of Acremonium showed the least adherence. No significant difference in the percentage spore adhesion was found between hydrophobic and hydrophilic materials. Furthermore, evidence was uncovered supporting the contention that, under dry conditions, electrostatic surface charges play a role in the adherence of fungal spores to surfaces, because adherence was positively correlated (Correlation coefficient = 0.70898, p = 0.001) to positive electrostatic charges on the lamellar surfaces. In the next part of the study, standard plate count methods were used to determine the relative adhesion of the above mentioned hyphomycetous fungi, as well as a polyphyletic group of yeasts, to the test surfaces submerged in 10 mM sodium phosphate buffer (pH 7.0). As was found with the experiments with the dry surfaces, both intraspecific and intergenus differences were uncovered. Overall, the fungi adhered better to hydrophilic surfaces than to hydrophobic surfaces. This indicated that the fungal surfaces were covered with relatively hydrophilic compounds such as carbohydrates. Subsequently, it was demonstrated that all the fungi adhered to plasma membrane glycoprotein coated polystyrene and the presence of fungal carbohydrates on the surfaces of the fungal propagules was confirmed using epi-fluorescence microscopy. Differences in the strategy of the fungal genera to release their airborne spores, as well as differences in their adhesion profiles for the series of test materials, may be indicative of a unique environmental niche for each genus. In future, this phenomenon should be investigated further.
AFRIKAANSE OPSOMMING: Hifomisete fungi is daarvoor bekend om te versprei deur middel van wind, water, en insek vektore. Maar nietemin, daar is bykans geen kennis m.b.t. hoe hierdie fungi van mekaar verskil t.o.v. hul vermoë om versprei te word deur omgewings vektore nie. Gevolglik was spoorvrystelling van kulture, verteenwoordigend van die genera Acremonium, Aspergillus en Penicillium gemoniteer om ‘n aanduiding te kry van primêre wyse van spoorverspreiding waardeur verteenwoordigers van die onderskeie genera ingespan word. Eksperimentele data ingewin, vanaf plaat tellings wat uitgevoer was op lug afkomstig vanuit die uitlaat-klep van die lugvloei kapsule, was onderwerp aan ‘n toepaslike analise van afwyking (ANOVA), deur gebruik te maak van ‘n SAS statistiese pakket. Intraspesie verskille is waargeneem t.o.v. lug spoorvrystelling. Desnieteenstaande was Penicillium meer suksesvol onder vogtige kondisies t.o.v. spoorvrystelling in vergelyking met Aspergillus en die Acremonium stam. Onder droë kondisies het verteenwoordigers van Aspergillus langer geneem om hul spore vry te stel as verteenwoordigers van onderskeidelik, Penicillium en Acremonium. Geen verskille was waargeneem m.b.t. spoorvrystelling in fisiologiese soutoplossing (FSO) tussen die verskillende filogenetiese stamme nie. Alhoewel dit nie bewys is nie, wil dit voorkom asof water as belangrike verspreidingsagent van die betrokke fungi dien, aangesien die spoel van kulture met FSO tot ‘n oombliklike enorme vrystelling van kolonie-vormende eenhede gelei het. Gevolglik, deur gebruik te maak van standaard plaattellings tegnieke, was spoor aanhegting van bogenoemde fungi aan sintetiese membrane, blaar snitte en insek eksoskelette wat verskil in terme van hidrofobisiteit en elektriese lading, ondersoek. Daar was gevind dat die aanhegtingsprofiele m.b.t. hierdie reeks toetsoppervlaktes van die verskillende genera verskil, wat op sigself ‘n aanduiding was van verskille in fisieschemiese eienskappe van die swamspoor oppervlaktes. Penicillium stamme het ‘n hoër aanhegtings vermoë aan die toetsoppervlaktes getoon as die aspergilli, terwyl die verteenwoordiger van Acremonium die laagste aanhegting getoon het. Geen betekenisvolle verskille i.t.v. persentasie spoor aanhegting was gevind tussen hidrofobiese en hidrofiliese oppervlakte nie. Daarbenewens was die argument dat spoorvrystelling onder droë kondisies beïnvloed word deur elektrostatiese oppervlak ladings, bevestig deur ons bevindinge, want aanhegting het positief gekoreleer (Korrelasie koëffisient = 0.70898, p = 0.001) met positiewe ladings op die oppervlaktes. ‘n Standaard plaattellingstegniek was aangewend in die volgende fasset van die studie om die relatiewe aanhegting van bogenoemde hifomisete fungi, sowel as ‘n polifilitiese groep giste aan die toetsoppervlaktes, gedompel in 10 mM natrium fosfaat buffer (pH 7.0) vas te stel. Intraspesie en intragenus verskille was weereens waargeneem, net soos in die geval van die eksperimente met die droë oppervlakte. In die algemeen het die swamme baie beter geheg aan hidrofiliese oppervlaktes in vergelyking met hidrofobiese oppervlakte. Dit was ‘n aanduiding dat die swamspoor oppervlaktes bedek was met relatiewe hidrofiliese verbindings bv. koolhidrate. Verder was daar bewys dat alle swamme ingesluit in hierdie studie die vermoë het om plasmamembraan glikoproteïn bedekte polistireen te bind, en gevolglik was die teenwoordigheid van van koolhidrate op die swamspore bevestig m.b.v epi-fluoresensie mikroskopie. Verskille in die strategie van swamme om spore in die lug vry te stel, sowel as verskille in die aanhegtingsprofiele vir ‘n reeks toetsmateriale, mag net ‘n aanduiding wees van ‘n unieke omgewings nis vir elke genus wat in hierdie studie ondersoek is. Hierdie verskynsel moet dus in die nabye toekoms nagevors word.
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Schlotman, Holly Lynn. "The Effects of Forest Fragmentation on the Reproductive Success of Spring Ephemeral Wildflowers and Their Pollinators." Wright State University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=wright1303161008.
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Adhikari, Subodh. "Effects of insect herbivory on plant architecture, flowering phenology, flower visitors’ activity and reproduction success in Cirsium Altissimum L." Diss., Wichita State University, 2013. http://hdl.handle.net/10057/6417.
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Insect exclusion experiments have demonstrated that insect herbivores can reduce host plant fitness through both direct and indirect mechanisms. I did an experiment on Cirsium altissimum (tall thistle), whose apical meristems are attacked by the larvae of Platyptilia carduidactyla (artichoke plume moth), during 2012 to determine whether apical meristem mining affects C. altissimum fitness and to determine whether these effects arise indirectly through plant-mediated effects on floral visitation. In a restored tall grass prairie, 180 tall thistle adult plants were randomly selected and assigned randomly to treat with insecticide, water and unmanipulated control. On these plants, I quantified effects of apical meristem mining on plant architecture, flowering phenology, flower visitors’ activity and seed production.
Apical meristem miners affected several aspects of plant architecture, including reducing plant height and increasing the proportion of axial flower heads, and many aspects of plant flowering phenology, including delaying flowering and date of maximum floral display. Apical meristem miners significantly decreased C. altissimum lifetime seed production, showing their strong effects on plant fitness. Bombus pensylvanicus and Melissodes desponsa were the most common visitors on C. altissimum flower heads. No strong effect of apical meristem miners was reported on the behavior of bee (Apidae) species, which may have resulted from the availability of the major visitors of C. altissimum flower heads throughout the flowering season. Overall, apical meristem mining strongly affected the plant reproduction success but no evidence was found to suggest that these effects on fitness of C. altissimum arose through changes in floral visitation. Being a monocarpic plant with little seed bank, reduced seed production by C. altissimum may translate into smaller population sizes.Thesis (Ph.D.)--Wichita State University, College of Liberal Arts and Sciences, Dept. of Biological Sciences
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Gustafsson, Christel. "Plant Population Dynamics and Biotic Interactions in two Forest Herbs." Doctoral thesis, Uppsala University, Evolutionary Biology, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-3285.
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In Sweden today, deciduous woodlands are often restricted to small isolated remnants of what it once was. Managing practices have changed concerning both cattle grazing and logging. Thus, dispersal, habitat requirements and their importance for forest species distributions become a relevant issue. Most of the species found in the deciduous flora are perennial herbs. I have examined population dynamics in the forest perennial Sanicula europaea, and its relation to environmental factors such as grazing, competition and spatial and temporal variation in such factors. Moreover I examined species distributions in relation to dispersal and habitat suitability in S. europaea and Dentaria bulbifera. To understand mechanisms behind the observed patterns I performed a number of experiments.
The results clearly demonstrated that the distribution and abundance of S. europaea was not dispersal limited, whereas the opposite held true for D. bulbifera. Moreover, mollusc exclusion increased recruitment thus influencing population dynamics in D. bulbifera. Leaf losses had negative effects on S. europaea individuals. These negative effects depended both on the extent, frequency and timing of the leaf losses and early losses were more severe than late. Population level effects of grazing were not negative as negative direct effects were counterblanced by positive indirect effects. The positive effects of grazing were mainly in terms of an increased recruitment.
In S. europaea, high variation in a life cycle transition was always coupled to low elasticity, and traits that varied much due to the examined environmental factors had little importance to population growth rate. A population level perspective is required to assess total effects of environmental factors. In perennial organisms such evaluations need to calculate integrated measures of the effects over the entire life cycle. Field studies spanning several years and demographic models are important to achieve these objectives.
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Rodney, Sara. "Effects of Glyphosate on Flower Production in Three Entomophilous Herbaceous Plant Species (Rudbeckia hirta L., Centaurea cyanus L. and Trifolium pratense L.)." Thesis, Université d'Ottawa / University of Ottawa, 2018. http://hdl.handle.net/10393/37964.
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Reproductive endpoints are generally not considered in regulatory risk assessments used to inform registration decisions for pesticides, and relatively few studies have examined effects of herbicides on reproduction in non-target plants. In two sets of greenhouse experiments using three wild species (Rudbeckia hirta L., Centaurea cyanus L. and Trifolium pratense L), effects on flowering phenology and inflorescence characteristics were investigated following low, drift-equivalent glyphosate exposure at an early bud stage. Weekly post-spray observations included the number of inflorescences, aborted buds and malformed inflorescences. In the experiment focusing on inflorescence characteristics (C. cyanus and T. pratense only), inflorescences and pollen were collected at five weeks post-spray to measure inflorescence dry weight, count the number of reproductive florets, estimate the amount of pollen per floret, and assess pollen germination in vitro. Flower production was adversely affected in all three species, including delays in flowering, significant increases in the number of aborted buds and malformed inflorescences, an overall reduction in the number of inflorescences produced, as well as a reduction in the duration of individual inflorescence bloom time (R. hirta and T. pratense assessed only). Inflorescence dry weight and in vitro pollen germination were significantly reduced for C. cyanus exposed to glyphosate, but not for T. pratense. However, both species experienced a significant reduction in the number of reproductive florets produced per inflorescence in response to glyphosate exposure. Neither species was observed to have significant reductions in the amount of pollen produced per reproductive floret. These results have important implications for risk assessment, demonstrating that current glyphosate use in Canada and elsewhere could be adversely affecting non-target flowering plants in field margins, as well as other taxa that rely on them, particularly pollinators.
Les effets sur la reproduction des plantes ne sont généralement pas pris en ligne de compte dans les évaluations réglementaires sur les risques des pesticides lors de leur homologation. De plus, relativement peu d'études ont examiné les effets des herbicides sur la reproduction des plantes non ciblées. Dans deux séries d'expériences en serres avec trois espèces sauvages (Rudbeckia hirta L., Centaurea cyanus L. et Trifolium pratense L), les effets sur la phénologie florale et les caractéristiques des inflorescences ont été étudiés après une faible exposition au glyphosate équivalente à la dérive durant la pulvérisation lorsque les plantes sont au début des boutons floraux. Des observations hebdomadaires post-pulvérisation ont été effectuées sur le nombre d'inflorescences, de bourgeons avortés et d’inflorescences malformées. Dans l'expérience portant sur les caractéristiques des inflorescences (C. cyanus et T. pratense seulement), les inflorescences et le pollen ont été recueillis cinq semaines après la pulvérisation pour mesurer le poids sec des inflorescences, compter le nombre de fleurons reproducteurs, estimer la quantité de pollen par fleur et évaluer la germination du pollen in vitro. La production de fleurs a été affectée chez les trois espèces, y compris des retards de floraison, des augmentations significatives du nombre de bourgeons avortés et d’inflorescences malformées, une réduction globale du nombre d'inflorescences produites et une diminution de la durée de floraison par inflorescence. (R. hirta et T. pratense évalués seulement). Le poids sec des inflorescences et la germination in vitro du pollen ont été significativement réduits chez C. cyanus exposé au glyphosate, mais pas chez T. pratense. Cependant, les deux espèces ont subi une réduction significative du nombre de fleurons reproducteurs produits par inflorescence en réponse à l'exposition au glyphosate. Aucune des deux espèces n'a montré de réduction significative de la quantité de pollen produit par fleuron. Ces résultats ont des implications importantes pour l'évaluation de risques, démontrant que le glyphosate, tel qu’utilisé présentement au Canada et ailleurs, pourrait nuire aux plantes à fleurs non ciblées retrouvées en bordure de champs, ainsi qu'à d'autres taxons qui en dépendent, particulièrement les pollinisateurs.
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Kornbluh, Andrea G. "The effect of population density and distribution on pollinator visits and fruit production in a self-incompatible herb, Apocynum cannabinum (Apocynaceae)." University of Akron / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=akron1574358774644695.
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