Thesis (Ph. D.)--University of Adelaide, Dept. of Soil Science, 1995? / Copies of author's previously published articles inserted. Includes bibliographical references (leaves 184-197).

Thesis (M.S.)--Oregon State University, 1989. / Typescript (photocopy). Includes bibliographical references. Also available on the World Wide Web.

Thesis (Ph.D.)--Murdoch University, 2004. / Thesis submitted to the Division of Science and Engineering. Includes bibliographical references (p. 199-210).

Thesis (M.S.)--University of Wisconsin -- La Crosse, 2009. / Includes bibliographical references (leaves 42-46)

Mycorrhizal colonization and types of mycorrhizae that formed on container-grown Douglas-fir, western hemlock, and western red cedar seedlings were determined in a nursery near Nanaimo, B.C. and under a range of field conditions on eastern Vancouver Island. Methods included a root clearing, bleaching, and staining procedure that allowed for accurate estimates of percentage colonization and some advantages in mycorrhiza characterization. The percentage of Douglas-fir and western hemlock short roots colonized by ectomycorrhizal fungi in the nursery was highly variable but over 99 percent of the mycorrhizae were formed by Thelephora terrestris. After one field season mycorrhizal colonization levels were between 72 and 93 percent on the new roots formed. The most difficult to regenerate site had the lowest percentage colonization and number of ectomycorrhizal types. T. terrestris mycorrhizae still had the highest relative abundance followed by Rhizopogon vinicolor (on Douglas-fir only), Cenococcum geophilum, Mycelium radicus atrovirens, Tujber-like, Sndogone-like, and 38 minor types of ectomycorrhizae. Some types of ectomycorrhizae were only present or common on specific sites. This included a type that formed spore-like structures on the mantle cystidia and a type that produced red-brown hyphal exudates. Douglas-fir seedlings artificially inoculated with R. vinicolor in an Oregon nursery were taller than control seedlings when outplanted but no height or weight difference was found after one field season. The 17 types of mycorrhizae that formed on the control seedlings were dominated in relative abundance by a type that was morphologically identical to that formed on the seedlings that were artificially inoculated with R. vinicolor. Western red cedar did not form mycorrhizae in the nursery but formed low levels of vesicular-arbuscular mycorrhizae in the field that included both fine and coarse endophytes. / Land and Food Systems, Faculty of / Graduate

No description available.

The overall objective of this thesis was to investigate how the arbuscular mycorrhizal (AM) symbiosis can affect the production of phytochemicals (antioxidants; rosmarinic and caffeic acid, RA & CA) in the shoots of basil (Ocimum basilicum L.). As a result of an increasing interest in natural/herbal medicines, more effort is now needed to produce herbal products of better quality, i.e. higher and standardised phytochemical concentrations. Thus, it was hypothesised that the naturally occurring AM fungi (AMF) could play an important role in improving the growth and phytochemical concentrations in medicinal herbs such as basil, as organic methods of cultivation are increasingly sought after to grow such plants. Despite a reasonable amount of information available in the literature on the changes of phytochemical concentrations in the roots of host plants following AM colonisation, very little is known about such processes in the aerial part of such plants. Furthermore, basil has hardly been studied as a host plant in AM research, and very little is known of its responsiveness to AM colonisation. As AMF are well known to improve phosphorus (P) uptake in their host plant, the first objective of this work was to obtain AM and non-mycorrhizal (NM) plants matched for tissue P concentrations and growth rates. Only under such conditions would it then be possible to separate benefits derived from improved plant P uptake from non-nutritional benefits. It was found that basil is highly responsive to P, and that under low or little P supply it is quite dependent on the AM symbiosis in order to grow. However, growth depressions were observed when growing basil in winter with Glomus intraradices, suggesting that the fungal symbiont can act as a strong sink of carbon (C) under such conditions. Thus, in order to obtain AM and NM plants with matched growth rates and tissue P concentrations, it was found that basil needed to be cultivated in summer in a soil/sand mixture with a ratio of 1:3 (w/w), along with 0.2 g/kg CaHPO4 and 25% of AM inoculum (AM plants). Under these conditions, AM plants grew as well as NM plants and G. caledonium and G. mosseae were shown to increase the concentrations of RA and CA in the shoots of basil, but not in roots. Such results were not an indirect effect of improved P uptake. In order to understand the mechanisms by which AMF increased RA and CA concentrations in basil, further experiments were set up to investigate the effect of 1) AM developmental stages, 2) nitrogen (N) supply and 3) phytohormone changes on the production of RA and CA in the shoots. None of these factors was found to contribute to increases in antioxidants in basil under AM symbiosis. Therefore, the mechanisms by which AMF affect RA and CA concentrations in basil still remain unknown. A final experiment was carried out to investigate the potential of an AM fungus to improve the growth of basil when challenged with a specific pathogen Fusarium oxysporum f.sp. basilici (Fob), which causes significant production losses. The results showed that inoculation of basil with G. mosseae not only improved plant growth compared to NM plants, but also conferred a protective effect against Fob. However, shoot antioxidant concentrations (RA, CA, total phenolics and essential oils) were not increased in AM plants compared to NM plants, and the mechanism of protection against Fob could not be elucidated. Due to the high variability of RA and CA concentrations obtained in AM plants in different experiments, it cannot be concluded that AMF confer an absolute advantage over uninoculated plants if the main concern is to obtain standardised concentrations of phytochemical in basil. On the other hand, the key results presented in this thesis do indicate that inoculating basil with AMF can be beneficial to improve its growth as well as antioxidant concentrations, compared to NM plants grown under similar conditions. Such results could be of potential interest to basil growers who wish to cultivate this medicinal herb organically (i.e. low P supply and no chemical fertilisers added). / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1330324 / Thesis (Ph.D) -- University of Adelaide, School of Earth and Environmental Sciences, 2008

No description available.

Under field conditions, vesicles were the most frequently observed mycorrhizal structures in sugar maple, while greenhouse grown seedlings formed more arbuscules. Seasonal fluctuations of vesicular-arbuscular mycorrhizae existed. Mycorrhizal associations formed within 30 days in the greenhouse. Arbuscules were usually formed from hyphal coils and occasionally from linear hyphae spreading from cell to cell. Degenerating arbuscules were not observed. The addition of basic cations increased the number of vesicles formed and decreased the overall infection rates and seedling growth. The uptake of calcium, magnesium, and nitrogen decreased, and potassium uptake increased as fertilization rates increased. Positive correlations existed between the incidence of arbuscules and plant growth and health and between the incidence of arbuscules and the uptake of calcium, magnesium, nitrogen and phosphorus, and with the uptake ratios and these elements with potassium. This suggests that vesicular-arbuscular mycorrhizae may in some way be regulating ionic balance in these seedlings.

Mycorrhiza is an association between a host plant and a soil fungus. Experiments were conducted to determine low temperature and soil disturbance effects on AM fungus winter survival and vigour in spring. The results showed that cool temperatures significantly reduced plant root growth and delayed AM formation. Glomus intraradices sporulation was highest at 23°C, while spore metabolic activity was significantly reduced with temperature below 10°C. Root length and colonization percentage decreased at 10°C. Mycorrhizal fungi increased 32P activity of leek leaves at a root zone temperature of 23°C 7 days after 32P injection, and at both 23°C and 15°C 14 days after injection. No difference was found at 0°C between mycorrhizal and non-mycorrhizal plants. Amounts of total and metabolically active spores and hyphae varied over sampling times. The infectivity of AM fungi was not affected by soil disturbance, but varied among the sampling times.