During the present study it was found that herbicides, applied at the
recommended dosage, has an inhibitory effect on fungi in vitro. However, when the
effect of herbicides on soil microbial and bacteria activity was tested in experimental
microcosms, it was found that soil with a high organic matter content had a buffer effect
on soil microbes.
Microbial activity increased after glyphosate treatment in rich soil microcosms,
indicating tha soil microbes utilized glyphosate as a source of carbon and nutrients or
that the toxicity of glyphosate to specific soil microflora and microfauna increased the
available nutrient base for increased activity of resistant organisms.
No significant differences were observed in terms of rhizosphere bacterial activity
between glyphosate resistant (GR) maize and soybean in comparison to their
conventional counterparts. Clay- and organic matter concentration in soil did however
have a significant influence. Soil with a high clay- and organic matter content had
higher microbial activity than soil with low clay- and organic matter content. Higher
ergosterol levels were also isolated from high clay- and organic matter soil than low
clay- and organic matter soil.
Dry root biomass of GR maize and soybean kultivars did not differ significantly
from their conventional counterparts. However, when glyphosate was applied to GR
maize and soybean, dry root biomass decreased significantly compared to GR maize
and soybean which received no glyphosate treatment. The same pattern was observed in terms of ergosterol concentrations, thus indicating that glyphosate had a physiological
effect on the respective crop roots.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:ufs/oai:etd.uovs.ac.za:etd-07182013-092646 |
| Date | 18 July 2013 |
| Creators | Wolmarans, Karen |
| Contributors | Prof WJ Swart |
| Publisher | University of the Free State |
| Source Sets | South African National ETD Portal |
| Language | en-uk |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.uovs.ac.za//theses/available/etd-07182013-092646/restricted/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to University Free State or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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