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Microorganisms, including presumptive nitrogen-fixing bacteria, in rhizospheres of fynbos plants and soils in Swartboskloof, Jonkershoek
Thesis (M. Sc.) -- University of Stellenbosch, 1992.
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| Format: | Thesis |
| Language: | English |
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Stellenbosch : Stellenbosch University
2012
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| _version_ | 1867613736233074688 |
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| access_status_str | Open Access |
| author | Dreyer, Karin Susanna |
| author2 | Loos, M. A. |
| author_browse | Dreyer, Karin Susanna Loos, M. A. |
| author_facet | Loos, M. A. Dreyer, Karin Susanna |
| author_sort | Dreyer, Karin Susanna |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (M. Sc.) -- University of Stellenbosch, 1992. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/69690 |
| institution | Stellenbosch University (South Africa) |
| language | English |
| last_indexed | 2026-06-10T12:40:53.123Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2012 |
| publishDateRange | 2012 |
| publishDateSort | 2012 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/69690 Microorganisms, including presumptive nitrogen-fixing bacteria, in rhizospheres of fynbos plants and soils in Swartboskloof, Jonkershoek Dreyer, Karin Susanna Loos, M. A. Stellenbosch University. Faculty of Science. Dept. of Microbiology. Fynbos -- South Africa -- Stellenbosch Rhizosphere Nitrogen-fixing microorganisms Microbial populations Soil microbiology -- South Africa -- Stellenbosch Jonkershoek (South Africa) Dissertations -- Microbiology Thesis (M. Sc.) -- University of Stellenbosch, 1992. Microbial populations in the rhizospheres of four fynbos plants on two soil forms, Glenrosa and Clovelly, in Swartboskloof, Jonkershoek, were studied during 1989 and 1990. The populations of fungi, bacteria and presumptive nitrogen-fixing bacteria in the rhizosphere soil and on the rhizoplane of Wasonia borbonica, Aristea major, Ficinia filiformis and Protea neriifolia, were estimated by dilution plate count and compared with populations in control (root-free) soil. The counts of rhizosphere soil organisms were usually higher than the corresponding count for the control soil, showing rhizosphere soil:control soil (R:S) ratios of 0.38 to 129.58. When the rhizoplane organisms were included with the rhizosphere soil organisms in the rhizosphere soil counts, the ratios increased to values (R′:S ratios) of 0.98 to 200.99. Seasonal variation of populations in the rhizosphere and control soils showed similar trends, with the highest counts during autumn or winter and the lowest during summer. Counts of rhizoplane organisms showed peaks in summer or winter. Counts for Glenrosa soil were usually higher than the corresponding counts for the Clovelly soil. Stimulation of the presumptive nitrogen-fixing bacteria near roots was often greater than the general stimulation of rhizosphere bacteria, and the highest R:S and R′:S ratios of 129.58 and 200.99, respectively, were recorded for the nitrogen-fixing bacteria in the rhizosphere of Wasonia borbonica. The fungi tended to show the least stimulation in the different rhizospheres (R:S and R′:S ratios to 31.48 and 34.34, respectively). It appeared from tentative identification studies of presumptive nitrogen-fixing bacteria, that most isolates belonged to the family Azotobacteraceae, comprising the genera Azotobacter and Azomonas, or the genus Beijerinckia, but further studies are necessary for their assignment to a particular genus or genera. Two yeasts isolated from the rhizosphere of Aristea major using nitrogen-free agar plates were identified as Cryptococcus laurentii. Nitrogen-fixing bacteria could play a significant role in nitrogen-poor fynbos soils, which lose a portion of their fixed nitrogen to the atmosphere wherever the vegetation is combusted by periodic prescribed or wild fires. Masters 2012-08-27T12:27:12Z 2012-08-27T12:27:12Z 1992 Thesis http://hdl.handle.net/10019.1/69690 en Stellenbosch University 130 pages : ill. application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Fynbos -- South Africa -- Stellenbosch Rhizosphere Nitrogen-fixing microorganisms Microbial populations Soil microbiology -- South Africa -- Stellenbosch Jonkershoek (South Africa) Dissertations -- Microbiology Dreyer, Karin Susanna Microorganisms, including presumptive nitrogen-fixing bacteria, in rhizospheres of fynbos plants and soils in Swartboskloof, Jonkershoek |
| title | Microorganisms, including presumptive nitrogen-fixing bacteria, in rhizospheres of fynbos plants and soils in Swartboskloof, Jonkershoek |
| title_full | Microorganisms, including presumptive nitrogen-fixing bacteria, in rhizospheres of fynbos plants and soils in Swartboskloof, Jonkershoek |
| title_fullStr | Microorganisms, including presumptive nitrogen-fixing bacteria, in rhizospheres of fynbos plants and soils in Swartboskloof, Jonkershoek |
| title_full_unstemmed | Microorganisms, including presumptive nitrogen-fixing bacteria, in rhizospheres of fynbos plants and soils in Swartboskloof, Jonkershoek |
| title_short | Microorganisms, including presumptive nitrogen-fixing bacteria, in rhizospheres of fynbos plants and soils in Swartboskloof, Jonkershoek |
| title_sort | microorganisms including presumptive nitrogen fixing bacteria in rhizospheres of fynbos plants and soils in swartboskloof jonkershoek |
| topic | Fynbos -- South Africa -- Stellenbosch Rhizosphere Nitrogen-fixing microorganisms Microbial populations Soil microbiology -- South Africa -- Stellenbosch Jonkershoek (South Africa) Dissertations -- Microbiology |
| url | http://hdl.handle.net/10019.1/69690 |
| work_keys_str_mv | AT dreyerkarinsusanna microorganismsincludingpresumptivenitrogenfixingbacteriainrhizospheresoffynbosplantsandsoilsinswartboskloofjonkershoek |