The overall objective of this project was to investigate the effects of the symbiotic association of plants with vesicular - arbuscular mycorrhizal fungi on the intensity of intraspecific competition and its consequences on population structure I performed four main glasshouse experiments using a non - cultivated species, Rhodanthe chlorocephala ssp rosea, or a cultivated species, Trifolium subterraneum. I grew the plants at different plant densities, under different levels of resources ( phosphorus and / or light ), in environments with homogeneous and / or patchy distribution of phosphorus ( P ). In pots with homogeneous distribution of P, the addition of P to R. chlorocephala and mycorrhizal infection in T. subterraneum increased plant biomass of single plants. However, these beneficial effects were reduced by increasing plant density. Shading of plants of T. subterraneum did not generally alter these effects. Mycorrhizal symbiosis and the addition of P always increased the intensity of plant intraspecific competition. In trays with patchy or homogeneous distribution of P, mycorrhizal infection and patchy distribution of P increased the total biomass and size inequality of populations of plants of T. subterraneum. Individual biomass was determined by the local soil P concentration in patchy environments and by mycorrhizal infection in low density treatments. Mycorrhizal infection, but not patchy P distribution, increased relative competition intensity. Asymmetric or symmetric distribution of resources between plants will change these size hierarchies. The distinction between these two types of distributions has lead to two different models explaining the interaction between competition and size inequality ( degree to which the biomass is concentrated within a small fraction of the population &# 40 Weiner and Thomas 1986 ) ) the resource depletion and resource pre - emption models ( Weiner and Thomas 1986, Weiner 1988b ). In the first model ( resource depletion ) competition reduces the relative growth rate of all the individuals by the same proportion, reduces variance of growth rates and reduces variation in sizes. Thus, in this model resource acquisition is proportional to plant size ( Weiner 1990 ). This model is also called symmetric or two - sided competition and applies when competition for nutrients predominates. It predicts that at high density, plants will be smaller but the population will have less inequality than at low density ( Weiner and Thomas 1986 ). In the second model ( resource pre - emption ), competition increases the variation in relative growth rates and increases variation in sizes. Large plants obtain a more than proportional share of the resources ( relative to sizes ) ( Weiner 1990 ) and this increases their competitive ability which results in a positive feedback on plant size. This phenomenon is also called snowball cumulation, asymmetric or one - sided competition and it was observed only when competition for light was predominant ( Wilson 1988a ). This second model predicts that at high density plant populations will have more inequality than at low density ( Weiner and Thomas 1986 ). Although these two models are generally accepted, alternative analyses and recent experiments show that the degree of asymmetry of the interaction depends on the spatial and temporal distribution of the resource, the spatial distribution of the individuals in the population, neighbourhood competition and the mobility of the resource ( Huston 1986 ; Miller and Weiner 1989, Weiner 1990, Bonan 1991 ). Weiner ( 1990 ) suggested that if nutrients are distributed homogeneously and the uptake is proportional to root size, the competitive interaction will be more symmetric, whereas if patches with more nutrients can be reached by large individuals, asymmetric competition will predominate. This hypothesis has not been tested yet. Turner and Rabinowitz ( 1983 ) found that populations with an initial random spatial distribution of individuals had an unexpected increase in size inequality. My results emphasise that the main effects of mycorrhizas at the individual level cannot be expected to be apparent at the population level, because of the influence of density - dependent processes. However, infected individuals with a strong response to the symbiosis would have an advantage in situations of competition. This scenario can explain the maintenance of the symbiotic ability even under conditions such as dense populations, where there is no obvious advantage of the symbiosis at the population level. / Thesis (Ph.D.)--Department of Soil and Water, 1998.

Thesis (Ph. D.)--University of Adelaide, 1986. / Includes bibliographical references (p. [i.e. leaves ] 267-277).

Thesis (Ph.D.)--University of Adelaide, Dept. of Soil Science, 1999. / Bibliography: leaves 135-156.

Diss. (sammanfattning) Uppsala : Univ., 2007. / Härtill 4 uppsatser. Med sammanfattning på svenska.

Thesis (Ph. D.)--University of Missouri-Columbia, 1997. / Typescript. Vita. Includes bibliographical references (leaves 174-183). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 1997. / Typescript. Vita. Includes bibliographical references (leaves 174-183). Also available on the Internet.

Bibliography: leaves 135-156. This study investigated the effects of the symbiotic association of plants with vesicular-arbuscular mycorrhizal fungi on the intensity of intraspecific competition and its consequences on popular structure. Four main glasshouse experiments were performed using the non-cultivated Rhodanthe chlorocephala ssp. Rosea, and the cultivated species Trifolium subterraneum grown at different plant densities, under different levels of phosphorus and light, and in environments with homogeneous and patchy distribution of phosphorus. Results emphasise that the main effects of mycorrhizas at the individual level may not by apparent at population level because of the influence of density-dependent processes. However, infected individuals with a strong response to the symbiosis would have an advantage in situations of competition.

CNPq / Artemisia annua L. é uma planta herbácea nativa da Ásia, muito utilizada como fonte de óleo essencial e artemisinina, uma lactona sesquiterpenica utilizada como princípio ativo antimalárico. Devido à grande demanda por esta molécula a busca pela melhoria da produção de A. annua é intensa. O objetivo deste estudo foi identificar a densidade de cultivo adequada para o maior rendimento de biomassa, artemisinina e óleo essencial, e a composição deste, além de comparar o desempenho produtivo de três variedades de A. annua para o cultivo na região Sudoeste do Paraná. Para isso, um experimento foi conduzido em delineamento de blocos ao acaso, com quatro repetições. Foram utilizadas três diferentes variedades de A. annua: Artemis F2, Artemis F1 e (2/39 x 5)x3M. Um segundo experimento foi conduzido com a variedade Artemis F2 em delineamento de blocos ao acaso, com três repetições. Os tratamentos utilizados foram: T1: 16.666 plantas ha-1, T2: 55.555 plantas ha-1, T3: 94.444 plantas ha-1 e T4: 133.333 plantas ha-1. Em pleno florescimento, o material vegetal dos dois experimentos foi colhido (aproximadamente 159 dias após o transplante) e seco até peso constante em estufa com circulação de ar a 35 ºC. A quantificação de artemisinina foi realizada por cromatografia em camada delgada com detecção por densitometria. A separação e quantificação das substâncias presentes no óleo essencial foram realizadas em cromatógrafo gasoso com detector de ionização de chama e, a identificação das mesmas foi feita em cromatógrafo a gás acoplado a espectrômetro de massas. Os resultados foram submetidos à análise da variância e ao teste de Tukey a 5% de probabilidade do erro para as variáveis qualitativas e a regressão do quadro da análise da variância para os tratamentos quantitativos. Todas as variedades testadas apresentaram elevada produção de massa seca de parte aérea, massa seca de folhas, produção de artemisinina e óleo essencial por área não diferindo estatisticamente ente si. As variedades Artemis F2 e Artemis F1 apresentaram maior relação folha/caule entre as variedades testadas. As variedades Artemis F1 e (2/39 x 5)x3M apresentaram maior teor de óleo essencial na matéria seca de folhas sendo mais recomendadas para o cultivo na região Sudoeste do Paraná, para fins de produção de óleo essencial. Os principais constituintes encontrados no óleo essencial das três cultivares foram a cânfora (39,69%), 1,8 cineol (12,66%), mirceno (9,29%), γ-muuroleno (4,95%), trans-b-farneseno (4,02%), que juntos somam em média 70,61% do óleo essencial das variedades testadas. Alterações na densidade de plantio não tiveram influência significativa sobre os constituintes majoritários do óleo essencial de A. annua variedade Artemis F2. Para as diferentes densidades as maiores produções de biomassa de folhas, artemisinina, teor de artemisinina na massa seca de folhas e óleo essencial foram obtidas nas densidades de 93.966 plantas ha-1, 80.0,71 plantas ha-1, 81.969 plantas ha-1 e 91.272 plantas ha-1 respectivamente. O teor de óleo essencial na massa seca de folhas não foi alterado pela densidade de plantio. A alteração na densidade de plantio influenciou na produção de canfeno, α-copaeno, acetato de mirtenila, γ- terpineno. Em todas as densidades de plantio a cânfora foi o constituinte majoritário com níveis superiores a 39% indicando que A. annua é uma fonte alternativa para a produção desta substância. Os monoterpenos foram a classe de compostos mais abundantes no óleo essencial de A. annua com 59,03% da constituição química e 33,91% pertence à classe dos sesquiterpenos. / Artemisia annua L. is a herbaceous plant native from Asia which is much used as a source of essential oil and artemisinin, a sesquiterpene lactone used as antimalarial active principle. The search in the improvement regarding the production of A. annua is intense due to the high demand for this molecule. The aim of this study was to identify the suitable planting density for a higher yield of biomass, artemisinin and essential oil, and the composition of this, and also compare the performance of three varieties of A. annua for cultivation in the Southwest region of Paraná. In order to this, an experiment was conducted in a randomized block design with four replications. Three different varieties of A. annua were used: Artemis F2, and Artemis F1 (2/39 x 5)x3M. A second experiment was conducted with Artemis F2 variety in a randomized block design with three replications. The treatments were: T1: 16.666 plants ha-1, T2: 55.555 plants ha-1, T3: 94.444 plants ha-1 and T4: 133.333 plants ha-1. The plant material of both experiments was harvested at flowering (approximately 159 days after transplantation) and dried until a constant weight in an oven with air circulation at 35 ° C. The quantification of artemisinin was performed by thin-layer chromatography and detected by densitometry. The separation and quantification of substances present in the essential oil were performed by gas chromatography with a flame ionization detector and the identification of them was performed by gas chromatography coupled to a mass spectrometer. The results were submitted to analysis of variance and Tukey's test at 5% of failure probability for qualitative variables and the regression of the analysis of variance for quantitative treatments. All the tested varieties showed an increasing production in relation to the dry mass of the aerial part, dry mass of leaves, artemisinin and essential oil production per area and they did not differ statistically between themselves. The varieties of Artemis F1 and Artemis F2 had a higher leaf/stem ratio among the varieties tested. The varieties of Artemis F1 and (2/39 x 5)x3M showed a higher content of essential oil in the dry mass of leaves, and due to this they are recommended for cultivation in the Southwest region of Paraná, for the essential oil production. The main compounds found in essential oils from the three cultivars were camphor (39.69%), 1.8 cineole (12.66%), myrcene (9.29%), γ-muuroleno (4.95%), trans - β-farnesene (4.02%), which together totalize an average 70.61% of the essential oil of the varieties tested. Changes in the planting density had no significant influence on the major constituents regarding the essential oil of A. annua variety of Artemis F2. Concerning the different densities, the highest production of leaf biomass, artemisinin, artemisinin content in the dry mass of leaves and essential oil were obtained at densities of 93,966 plants ha-1, 80.0,71 plants ha-1, 81 969 plants ha-1 and 91,272 plants ha-1 respectively. The essential oil content in dry mass of leaves was not affected by the planting density. The alteration in planting density influenced the production of camphene, α-copaene, mirtenila acetate, γ-terpinene. Regarding all the planting densities, camphor was the major constituent with levels above 39% indicating that A. annua is an alternative source for the production of this substance. Monoterpenes were the most abundant class of compounds in essential oil of A. annua with 59.03% of the chemical constitution and 33.91% belong to the class of sesquiterpenes.

CNPq / Artemisia annua L. é uma planta herbácea nativa da Ásia, muito utilizada como fonte de óleo essencial e artemisinina, uma lactona sesquiterpenica utilizada como princípio ativo antimalárico. Devido à grande demanda por esta molécula a busca pela melhoria da produção de A. annua é intensa. O objetivo deste estudo foi identificar a densidade de cultivo adequada para o maior rendimento de biomassa, artemisinina e óleo essencial, e a composição deste, além de comparar o desempenho produtivo de três variedades de A. annua para o cultivo na região Sudoeste do Paraná. Para isso, um experimento foi conduzido em delineamento de blocos ao acaso, com quatro repetições. Foram utilizadas três diferentes variedades de A. annua: Artemis F2, Artemis F1 e (2/39 x 5)x3M. Um segundo experimento foi conduzido com a variedade Artemis F2 em delineamento de blocos ao acaso, com três repetições. Os tratamentos utilizados foram: T1: 16.666 plantas ha-1, T2: 55.555 plantas ha-1, T3: 94.444 plantas ha-1 e T4: 133.333 plantas ha-1. Em pleno florescimento, o material vegetal dos dois experimentos foi colhido (aproximadamente 159 dias após o transplante) e seco até peso constante em estufa com circulação de ar a 35 ºC. A quantificação de artemisinina foi realizada por cromatografia em camada delgada com detecção por densitometria. A separação e quantificação das substâncias presentes no óleo essencial foram realizadas em cromatógrafo gasoso com detector de ionização de chama e, a identificação das mesmas foi feita em cromatógrafo a gás acoplado a espectrômetro de massas. Os resultados foram submetidos à análise da variância e ao teste de Tukey a 5% de probabilidade do erro para as variáveis qualitativas e a regressão do quadro da análise da variância para os tratamentos quantitativos. Todas as variedades testadas apresentaram elevada produção de massa seca de parte aérea, massa seca de folhas, produção de artemisinina e óleo essencial por área não diferindo estatisticamente ente si. As variedades Artemis F2 e Artemis F1 apresentaram maior relação folha/caule entre as variedades testadas. As variedades Artemis F1 e (2/39 x 5)x3M apresentaram maior teor de óleo essencial na matéria seca de folhas sendo mais recomendadas para o cultivo na região Sudoeste do Paraná, para fins de produção de óleo essencial. Os principais constituintes encontrados no óleo essencial das três cultivares foram a cânfora (39,69%), 1,8 cineol (12,66%), mirceno (9,29%), γ-muuroleno (4,95%), trans-b-farneseno (4,02%), que juntos somam em média 70,61% do óleo essencial das variedades testadas. Alterações na densidade de plantio não tiveram influência significativa sobre os constituintes majoritários do óleo essencial de A. annua variedade Artemis F2. Para as diferentes densidades as maiores produções de biomassa de folhas, artemisinina, teor de artemisinina na massa seca de folhas e óleo essencial foram obtidas nas densidades de 93.966 plantas ha-1, 80.0,71 plantas ha-1, 81.969 plantas ha-1 e 91.272 plantas ha-1 respectivamente. O teor de óleo essencial na massa seca de folhas não foi alterado pela densidade de plantio. A alteração na densidade de plantio influenciou na produção de canfeno, α-copaeno, acetato de mirtenila, γ- terpineno. Em todas as densidades de plantio a cânfora foi o constituinte majoritário com níveis superiores a 39% indicando que A. annua é uma fonte alternativa para a produção desta substância. Os monoterpenos foram a classe de compostos mais abundantes no óleo essencial de A. annua com 59,03% da constituição química e 33,91% pertence à classe dos sesquiterpenos. / Artemisia annua L. is a herbaceous plant native from Asia which is much used as a source of essential oil and artemisinin, a sesquiterpene lactone used as antimalarial active principle. The search in the improvement regarding the production of A. annua is intense due to the high demand for this molecule. The aim of this study was to identify the suitable planting density for a higher yield of biomass, artemisinin and essential oil, and the composition of this, and also compare the performance of three varieties of A. annua for cultivation in the Southwest region of Paraná. In order to this, an experiment was conducted in a randomized block design with four replications. Three different varieties of A. annua were used: Artemis F2, and Artemis F1 (2/39 x 5)x3M. A second experiment was conducted with Artemis F2 variety in a randomized block design with three replications. The treatments were: T1: 16.666 plants ha-1, T2: 55.555 plants ha-1, T3: 94.444 plants ha-1 and T4: 133.333 plants ha-1. The plant material of both experiments was harvested at flowering (approximately 159 days after transplantation) and dried until a constant weight in an oven with air circulation at 35 ° C. The quantification of artemisinin was performed by thin-layer chromatography and detected by densitometry. The separation and quantification of substances present in the essential oil were performed by gas chromatography with a flame ionization detector and the identification of them was performed by gas chromatography coupled to a mass spectrometer. The results were submitted to analysis of variance and Tukey's test at 5% of failure probability for qualitative variables and the regression of the analysis of variance for quantitative treatments. All the tested varieties showed an increasing production in relation to the dry mass of the aerial part, dry mass of leaves, artemisinin and essential oil production per area and they did not differ statistically between themselves. The varieties of Artemis F1 and Artemis F2 had a higher leaf/stem ratio among the varieties tested. The varieties of Artemis F1 and (2/39 x 5)x3M showed a higher content of essential oil in the dry mass of leaves, and due to this they are recommended for cultivation in the Southwest region of Paraná, for the essential oil production. The main compounds found in essential oils from the three cultivars were camphor (39.69%), 1.8 cineole (12.66%), myrcene (9.29%), γ-muuroleno (4.95%), trans - β-farnesene (4.02%), which together totalize an average 70.61% of the essential oil of the varieties tested. Changes in the planting density had no significant influence on the major constituents regarding the essential oil of A. annua variety of Artemis F2. Concerning the different densities, the highest production of leaf biomass, artemisinin, artemisinin content in the dry mass of leaves and essential oil were obtained at densities of 93,966 plants ha-1, 80.0,71 plants ha-1, 81 969 plants ha-1 and 91,272 plants ha-1 respectively. The essential oil content in dry mass of leaves was not affected by the planting density. The alteration in planting density influenced the production of camphene, α-copaene, mirtenila acetate, γ-terpinene. Regarding all the planting densities, camphor was the major constituent with levels above 39% indicating that A. annua is an alternative source for the production of this substance. Monoterpenes were the most abundant class of compounds in essential oil of A. annua with 59.03% of the chemical constitution and 33.91% belong to the class of sesquiterpenes.

Paronychia virginica Spreng. (Caryophyllaceae) is a perennial evergreen herb of exposed, relatively xeric habitats. Approximately 10 mid-Appalachian populations remain in Virginia, West Virginia, and Maryland and are disjunct from populations located primarily in Texas, Oklahoma, and Arkansas. A study was conducted to test the hypothesis that eastern and western populations differ significantly and, therefore, represent at least two distinct taxa. Statistical analyses of 8 qualitative and 24 quantitative morphological characters indicated very highly significant (P < 0.001) variation between eastern and western populations of P. virginica. Characters differing most significantly included sepal pubescence, awn length, awn pubescence, awn curvature, length-width ratio of leaves, and shape of leaf apices. Starch gel electrophoresis was performed and six enzyme systems/nine loci (EST-2, EST-3, LAP, MDH-1, MDH-2, PGI, PGM-1, PGM-2, and SKDH) were identified as being consistently scorable and informative. Although gene flow between populations of P. virginica was shown to be restricted (mean FST = 0.353), populations are maintaining relatively high levels of genetic diversity. Genetic variability was quantified for each population and mean values for number of alleles per locus (A), percent loci polymorphic (P), and expected heterozygosity (HEXP) were found to be 1.95, 47.22%, and 0.204, respectively, exceeding those values reported for seed plants, widespread species, and endemic species. Hierarchical F statistics suggest higher levels of genetic variability within individual populations than among populations, regardless of geographic location. All statistically significant (P < 0.05) deviations from Hardy-Weinberg equilibrium indicated a deficiency in heterozygotes at the respective loci. Considering results from both the morphometric and allozyme analyses, the current author suggests recognizing two distinct subspecies, P. virginica subsp. virginica in the eastern U.S. and P. virginica subsp. scoparia in the south-central U.S. Conservation efforts should be focused on the maintenance of existing populations in both eastern and western regions of the U.S. in order to preserve the genetic and evolutionary potential of these taxa. / Master of Science