Thesis (Ph. D.)--College of William and Mary. / Vita. Includes bibliographical references. Also available online.

The application of seaweed concentrates to plants has been shown to enhance growth and improve yield parameters. How these natural products elicit their beneficial responses is still unclear. While many of the growth responses have been attributed to cytokinins, it is obvious that this group of plant hormones cannot account for all the beneficial effects incurred from seaweed use. This study was therefore initiated to investigate the effects of a commercial seaweed concentrate (Kelpak) on several aspects of plant growth and development. Tentative determination of plant growth regulators in the seaweed concentrate (SWC) using bioassay systems, indicated the presence of compounds with gibberellin- , abscisic acid- and auxin-like properties. Tentative identification of the auxins present in the SWC and Ecklonia maxima using High Performance Liquid Chromatography revealed the presence of tryptophan, indole-3-acetamide, indole-3- acetic acid, indole-3-carboxylic acid and indole-3-acetaldehyde. The effect of SWC on the growth of nodal potato explants cultured in vitro was examined. 0.2% SWC significantly accelerated shoot growth and development. When applied at a concentration of 0.4% the number of axillary shoots per node increased. This treatment also stimulated the development of potato tubers on the shoots. The SWC was also shown to enhance the growth of tomato (Lycopersicon esculentum Mill.) roots cultured in vitro. Filtration of the SWC indicated a promotory filtrate phase and an inhibitory cell wall phase. ' The application of the SWC to nematode-infested roots, cultured in vitro, reduced the degree of infestation In susceptible roots but induced host/parasite compatibility in a resistant variety. One of the most pronounced effects noted with seaweed application was the promotion of adventitious roots on several species of garden plants. The application of similar dilutions to Eucalyptus cuttings increased the average root mass but had little effect on the number of roots initiated per cutting. The rooting factors, purified by HPLC, were tentatively identified as indole-3-acetamide, indole-3-acetic acid, indole-3-carbo. xylic acid or indole-3-acetaldehyde by co-chromatography with authentic standards. Finally, the effect of seaweed concentrate on the growth of tomato plants grown in nematode-infested soil was investigated. SWC applied as a soil drench, improved plant vigour, significantly increased shoot and root fresh weights and resulted in a marked reduction in the number of nematode galls per unit length and per unit weight of root. Plants treated with a foliar spray of SWC were invariably the first to produce ripe fruit. Total yield was improved by over 10%. Ashing the SWC indicated that the active constituents are possibly of an organic nature. Filtering the SWC confirmed earlier reports that promotory and inhibitory compounds are present in the concentrate. Chromatographic separation of the SWC into 10 Rf zones indicated the presence of several components with growth regulatory properties. It was found that the same fractions that improved plant growth also reduced nematode infestation. The significance of these findings and the possible relationship between the endogenous plant growth regulators in Ecklonia maxima and the effect of the SWC on plant growth is discussed. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1990.

Thesis (M.S.)--University of Hawaii at Manoa, 2007. / Includes bibliographical references (leaves 89-96). / ix, 96 leaves, bound ill. 29 cm

Thesis (M.S.)--University of Hawaii at Manoa, 2006. / Includes bibliographical references (leaves 28-33). / 50 leaves, bound ill. 29 cm

This study investigated the role of grazing as a possible cause for the upper limit of distribution of algae on a typical South African south coast.

In response to concern that excessive macroalgal growth and accumulation was occurring in some inshore areas of Lake Macquarie, the distribution, abundance and seasonality of macroalgae was investigated in relation to nutrient input and power station cooling water. Macroalgal dry weight biomass was measured at ten sites on a monthly basis for two years, with an analysis of community structure conducted using Multi-Dimensional Scaling. The macroalgal community in Lake Macquarie was typical of those found in other New South Wales coastal lagoons, exhibiting considerable spatial and temporal variation. A close similarity was observed in macroalgal community structure at sites affected by urban nutrient input, these being characterised by a high biomass often attributable to only one or two species. These nuisance macroalgae were mostly green algae, which were almost entirely absent from other sites. Biomass at sites affected by urban nutrient input was generally within the range documented for eutrophic estuaries elsewhere. Analysis of macroalgal community structure showed no evidence of large-scale changes macroalgal communities attributable to the effects of power station cooling water except within 500m of the outfall. At sites affected by a 1-2??C temperature increase, community structure and the magnitude of the biomass were similar to sites deemed as being relatively free of human impact. A reduction in species diversity occurred only within the immediate discharge zone, where water temperatures were approximately 6??C above ambient temperatures. Excessive growth of nuisance macroalgal species was not observed at any of the sites influenced by power station cooling water. There were no distinct patterns in seasonality of macroalgal growth in this study, though the greatest biomass appeared to occur in spring. The irregular temporal variation in macroalgal growth suggests that the most significant factors affecting growth occur on a time scale of weeks to months. It is therefore likely nutrient input to the nearshore through surface runoff is an important influence on the distribution and abundance of macroalgae in Lake Macquarie. This emphasises the need to reduce nitrogen and phosphorus input from urban sources in Lake management.

This thesis describes the isolation and structure elucidation of ten novel secondary metabolites from one fungus (Pycnoporus cinnabarinus), four lichens (Chrysothrix xanthina, Candelaria concolor, Ramalina glaucescens and Xanthoria parietina), three algae (Plocamium mertensii, Laurencia filiformis and Laurencia elata), two plants (Haemodorum simplex and Dianella callicarpa) and one sponge (Dactylospongia sp). The structures of these isolated compounds were elucidated by a combination of spectroscopic and chemical methods. This thesis also reports two new crystal structures, the identification of two new methylsilylated derivatives as well as the isolation of thirty seven previously reported compounds in which the complete structural assignment by one and two dimensional nuclear magnetic resonance spectroscopy (NMR) has been carried out on known compounds with incomplete or no NMR spectroscopic data. Furthermore, detailed spectroscopic analyses resulted in the re assignment of 1H and 13C chemical shifts for several previously isolated natural products. The biological screening (antimicrobial, antiviral and antitumor assays) of crude extracts and isolated natural products has also been presented. The application of chemical profiling techniques including GCxGC and high pressure liquid chromatography-nuclear magnetic resonance (HPLC-NMR) were utilised to assist with the natural product dereplication process (chemical profiling), monitor chemical degradations in situ and to identify the presence of new natural products and artefacts. In total, fifteen separate terrestrial and marine organisms were investigated.

Thesis (Ph.D.)--University of Western Australia, 2006.

Thesis (Ph.D.)--University of Wollongong, 2007. / Typescript. Includes bibliographical references: page 256-281.

Thesis (M.S.)--Baylor University, 2008. / Includes bibliographical references (p. 68-74)