Magister Scientiae - MSc (Botany)http://hdl.handle.net/11394/322024-03-19T10:15:47Z2024-03-19T10:15:47ZEffect of simulated acid rain on seed germination and on growth and mineral nutrition of Lycopersicon esculentum var. Red kakiMarsh, Frans Ahttp://hdl.handle.net/11394/103542023-06-28T00:01:36Z1993-01-01T00:00:00ZEffect of simulated acid rain on seed germination and on growth and mineral nutrition of Lycopersicon esculentum var. Red kaki
Marsh, Frans A
The phenomenon of acid rain is not new. It has been active for more than a billion years (Abelson, 1983). The term "acid rain" was introduced as early as 1872 by Robert Angus Smith, the world's first air pollution control inspector, who measured pH values of precipitation considerably lower than 5,6 (the pH of distilled water in equilibrium with atmospheric CO2) in and around northern English industrial cities. At this time relatively little interest was shown in the topic (Anon, 1984;BeI1, 1988). Widespread interest in the topic began in the mid - 1970's, when Scandinavian studies identified a downward trend in pH of precipitation in southern Norway and Sweden accompanied by an increase in acidity of lakes and rivers (Bell, 1988). At the same time' predictions were made that Swedish soils would become progressively acidified, with a concommitant fall in timber production. Initially there appeared to be little evidence to support the latter contention and research concentrated on the causes of the loss of fish, untill the early L980's when a serious forest decline was observed in Central Europe, which has been popularly ascribed to acid rain (Bell, 1988)'
>Magister Scientiae - MSc
1993-01-01T00:00:00ZThe effects of clipping and burning on the allocation of total nonstructural carbohydrates and selected mineral nutrients in Imperata cylindrica (L.) RaeuschelMitchell, Faghriehttp://hdl.handle.net/11394/103332023-06-23T00:02:05Z1999-01-01T00:00:00ZThe effects of clipping and burning on the allocation of total nonstructural carbohydrates and selected mineral nutrients in Imperata cylindrica (L.) Raeuschel
Mitchell, Faghrie
The rhizomatous grass, Imperata cylindrica, occurs in the Cape Flats Nature Reserve (CFNR), South Africa. It is recognised globally as a weed of crop plants. The response of this weed to defoliation, in the forms of clipping and burning, was studied in terms of its total nonstructural carbohydrates and mineral nutrition. This study will serve as a starting point for later studies aiming to control this weed. It was confirmed that the underground stems or rhizomes serve as the major storage tissue for total nonstructural carbohydrates and mineral nutrients. These rhizomes also make up the largest part of its biomass and hence defoliation was found not to significantly decrease stem total nonstructural carbohydrates or mineral nutrients. The burn treatment induced faster replacement of above ground material than the other defoliation treatments. The burn and basal clipping treatments induced higher leaf nitrogen and phosphorus levels following defoliation. These two treatments also led to significantly higher number of tillers after defoliation and were also the only treatments which induced flowering. The one-off defoliation which was applied at the start of this study, was found to be ineffective in taxing I. cylindrica's resources to the point where it would be vulnerable to eradication. It is hence recommended that future studies on the grass should entail multiple defoliations in order to develop a defoliation regime which will exterminate the grass.
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1999-01-01T00:00:00ZBiomonitoring as a means to determine the pollution level in StellenboschDavis, Shaun Andrehttp://hdl.handle.net/11394/103252023-07-19T08:58:16Z1991-01-01T00:00:00ZBiomonitoring as a means to determine the pollution level in Stellenbosch
Davis, Shaun Andre
A pollution survey was done in Stellenbosch, along two transects. One was south-east and the north-east of the Oorrobrick brickfield the focal point of this study. Pine and Oak trees, chasman the leaves and lichens were used as bio-indicators for this survey. The levels of fluoride and sulphur decreased with distance from the main pollution source. Exceptionally high levels were recorded in the pine and oak trees within 1.5. km from the brickworks. The availability of calcium and magnesium in the leaves of pine and oak trees appeared to be negatively affected due to their binding with F- to form insoluble compounds. The brickfield proved to be a major source of especially copper and iron, as their levels in the bark material decreased with increasing distance. Lead levels were found to be correlated with vehicular traffic in the area. There was some evidence that the iron levels were also linked to the lead concentrations in the bark.
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1991-01-01T00:00:00ZThe experimental cultivation and alginate properties of South African kelpsHarper, Mellisa Nhttp://hdl.handle.net/11394/102942023-06-21T00:01:20Z2003-01-01T00:00:00ZThe experimental cultivation and alginate properties of South African kelps
Harper, Mellisa N
Alginates are used in various industries and the quality of alginates used must be controlled. Alginates used for medical purposes must be of a very high quality. The cost of obtaining high-quality alginate is high and very time-consuming. A simple procedure is described for the purification and extraction of alginate from the kelp Laminaria pallida. The kelp was divided into different sections, including the blades. The stipes were cleaned and some were peeled and extractions were made of all the different sections including the peels. Analysis of the purified alginate showed a protein content below detectable levels and a very low polyphenol content. The purified alginate was
highly viscous, with24 - 29 centipoise for a0.l %o solution. Using this method a higher quality alginate can be obtained from any section of the kelp and this will help in more medical advances
Magister Scientiae (Biodiversity and Conservation Biology)
2003-01-01T00:00:00Z