The present study aimed to examine the effects of root colonization in tomato, Solanum lycopersicum L. cv. Moneymaker, by the arbuscular mycorrhizal (AM) fungus, Glomus intraradices Shenck and Smith, on alleviating salt stress. I postulated that AM symbiosis increases tomato plant performance to salt stress. Two greenhouse experiments were done according to a randomized factorial experimental design. The results showed a significantly higher level of AM root colonization that also occurred earlier in salt than non-salt treated plants. There were also positive interactions between root colonization levels and the alleviation of salt stress; these contributions resulted initially on higher root fresh mass (FM), later on shoot FM, and DM, and higher phosphorus and unchanged potassium concentrations in roots. The effects observed in salt-treated plants were significant when root colonization levels were significantly different than those observed in non-salt treated plants. This suggests a relationship between the level of root colonization and the alleviation of salt stress in plants. The attempt to use molecular techniques to detect early root colonization was quite successful in detecting the presence of G. intraradices in AM plants. However, it was not possible to detect the presence of the AM fungus as early as by classical root staining. This was observed presumably because sampling methods were different. In general, the results support the hypothesis that AM root colonization contributes to some extent to salt resistance of tomato plants.

Thesis (doctoral)--Oulun yliopisto, 2003. / Includes bibliographical references. Also available in electronic format.

Thesis (Ph. D.)--University of Queensland, 2002. / Includes bibliographical references.

Mycorrhizae improve plant growth and ecosystem sustainability by forming a symbiotic association with higher plants including the economically important willows (Salix spp.). With the recognition of the importance of mycorrhizae in terrestrial ecosystems, inoculation of plants with mycorrhizae is becoming a common practice in agricultural and land reclamation industries. However, little information is available on important ecological parameters such as soil aggregation, soil organic carbon content (SOC) and mycorrhizal communities associated with willow rhizospheres in response to mycorrhizal inoculation in willow systems. The main objectives of this research were to explore how commercial mycorrhizal inoculation of willows impacts (1) percent water-stable soil aggregates (%WSA); (2) indigenous arbuscular mycorrhizal fungi (AMF) and ectomycorrhizal fungi (EMF) community composition associated with different size soil aggregates; (3) SOC, and (4) willow growth. These objectives were examined under both greenhouse and field conditions. Using molecular approaches, we observed the existence of spatial variability in indigenous AMF communities among different soil aggregate size classes. This spatial variability varied with type of soil and could be reduced by inoculating with a commercial AMF inoculant. The indigenous EMF diversity was low and did not show spatial heterogeneity among soil aggregates, but it did vary with soil type. In addition, other parameters, including %WSA, SOC within the willow rhizosphere, and willow plant growth also varied by soil type and changed in association with commercial mycorrhizal inoculation. In the field experiment, soil extracts from willow nursery soil had comparable plant growth promotion with commercial mycorrhizal inoculation, and altered the AMF community associated with bulk soil and soil aggregates in the willow rhizosphere. These results suggest that historically superior willow growth in the willow nursery soil could be due to pre-existing soil microbiological factors. Overall this research indicates that AMF and EMF inoculation has the potential to influence the composition of the AMF community, but had little influence on the composition of the EMF community in the systems tested. / Natural Sciences and Engineering Research Council of Canada

The present study aimed to examine the effects of root colonization in tomato, Solanum lycopersicum L. cv. Moneymaker, by the arbuscular mycorrhizal (AM) fungus, Glomus intraradices Shenck and Smith, on alleviating salt stress. I postulated that AM symbiosis increases tomato plant performance to salt stress. Two greenhouse experiments were done according to a randomized factorial experimental design. The results showed a significantly higher level of AM root colonization that also occurred earlier in salt than non-salt treated plants. There were also positive interactions between root colonization levels and the alleviation of salt stress; these contributions resulted initially on higher root fresh mass (FM), later on shoot FM, and DM, and higher phosphorus and unchanged potassium concentrations in roots. The effects observed in salt-treated plants were significant when root colonization levels were significantly different than those observed in non-salt treated plants. This suggests a relationship between the level of root colonization and the alleviation of salt stress in plants. The attempt to use molecular techniques to detect early root colonization was quite successful in detecting the presence of G. intraradices in AM plants. However, it was not possible to detect the presence of the AM fungus as early as by classical root staining. This was observed presumably because sampling methods were different. In general, the results support the hypothesis that AM root colonization contributes to some extent to salt resistance of tomato plants.

"June 2002" / Bibliography: leaves 179-194. / 194 leaves : ill. (col.), plates (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / The overall aim of the research presented in this thesis was to determine if the growth and function of external hyphae of Arbuscular Mycorrhizal (AM) fungi is affected by changes in soil pore size. / Thesis (Ph.D.)--University of Adelaide, Dept. of Soil and Water, 2002

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

Thesis (Ph.D.) -- University of Adelaide, Dept. of Soil and Water, 2001. / Bibliography: leaves 106-132.

Thesis (M.Sc.)--University of Western Australia, 2003.

Thesis (Ph. D.)--West Virginia University, 2000. / Title from document title page. Document formatted into pages; contains vii, 146 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 126-145).