Magister Scientiae - MSc (Botany)

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Now showing 1 - 12 of 12

Effect of simulated acid rain on seed germination and on growth and mineral nutrition of Lycopersicon esculentum var. Red kaki
(University of the Western Cape, 1993) Marsh, Frans A; Raitt, L.M; Aalbers, J
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)'
The effects of clipping and burning on the allocation of total nonstructural carbohydrates and selected mineral nutrients in Imperata cylindrica (L.) Raeuschel
(University of the Western Cape, 1999) Mitchell, Faghrie; Raitt, Lincoln; Aanbers, Johannes
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.
Biomonitoring as a means to determine the pollution level in Stellenbosch
(University of the Western Cape, 1991) Davis, Shaun Andre; Raitt, L M; Aalbers, J
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.
The experimental cultivation and alginate properties of South African kelps
(University of the Western Cape, 2003) Harper, Mellisa N; Keats, Derek W.; Anderson, Robert J.
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
A critical analysis of aspects pertaining to the teaching of the ecology section of the standard eight biology syllabus.
(University of the Western Cape, 1991) Wagiet, R; Herman, H.; Kenzie, M.C
In this study an attempt has been made to investigate how the Ecology section (suitable for fostering awareness and concern for the environment) of the standard eight Biology syllabus is taught. Since fieldwork and related exercises are integral components of ecology, teachers are strongly advised to venture into such activities. It was ascertained that the restraints wh ich inhibited teachers from undertaking meaningful endeavours such as fieldwork include: an inadequate pre-serv ice training in ecology, with limited or no experience of fieldwork techniques; lack of time and, syllabus constraints. It is therefore recommended that there should be a restructuring of the content and approach followed by the tertiary institutions involved in teacher training. Additionally, it should be noted that in the absence of inservice teaching programmes, and, with the weaknesses identified in the textbooks, difficult sections experienced by the teachers (for example, nutrient cycling), will continue to be problematic, and unsuitable methods of ecology teaching will be perpetuated
Triterpene glycosides chemically defend the south african kelp bed sea cucumber, Pseudocnella insolens (echinodermata : holothu roidea), against predation.
(University of the Western Cape, 1997) Brown, R.E; Keats, D.W
The small, subtidal sea cucumber, Pseudocnella insolens appears to have no obvious protection from predation, yet it occurs in dense colonies covering rocky areas and appears to have few predators. Laboratory-based feeding rials were developed to assess the deterrent effects of various purified sea cucumber extract
Genetic variation among verticillium dahliae isolates using pathogenicity and aflp analysis
(University of the Western Cape, 1999) Visser, Marinda; Klaasen, J. A.; Mcleod, A
Soilborne plant pathogenic fungi have had an important economic and social impact on humans since the evolution of agricultural societies (Stakman, 1959). In South Africa, the soilborne pathogen Verticillium dahliae Kleb, causes wilt and early dying, which results in extensive losses in the production of potatoes and tomatoes (Uys et al., 1995). Control of soilborne diseases however remains elusive. Since roots are hidden from view, disease development and subsequent yield loss are not recognised until harvest or when symptom expression, in the form of plant death, occurs, by which time it is too late to react with any control measure. Management of soil-borne diseases is a continual challenge to growers. The structural, physical, and biological complexity of the soil environment, in which pathogens interact with plant roots, inherently limits the options available for disease control. The oldest and most fundamental approach employed by man to control plant diseases is the modification of cultural practices. Most cultural practices used to control plant diseases are preventative in nature. Some of the most proven control measures remain resistance and, in some situations, fungicides. Despite efforts to effectively combine these options with other control strategies, soilborne diseases continue to constrain crop production (Ligoxigakis & Vakalounakis 1992). Therefore, the study of soilborne diseases and their control poses a continuing challenge for plant pathologist.
Vegetation relationships of priority conservation sites on the Cape flats
(University of the Western Cape, 1992) Fredericks, Mogamat Fuad; McKenzi, Bruce
The physical environment of the cape Frats is outlined. The plant communities of twenty-one priority conservation sites are classified. Twenty-five communities, grouped into 15 associations, 8 alliances, 4 orders, 2 subclasses and a single class are defined. This is based entirely on floristic features, following the Braun-Blanquet approach and application of the code of phytosociological Nomenclature. These syntaxa are systematically described with reference to floristic, structural and macroenvironmental features . The distribution of the communities are indicated on 1:10 000 scale maps of the study sites. The communities are described further in relation to soil chemical and physical variables. The analysis indicates that soil chemical variables are more important in determining vegetation-soil relationships than physical variables. The main variables are soil Ca, pH, p, K, Nd, bulk density, moisture regime, t medium sand and t fine sand. The "general summary and recommendations" serve as a guideline for interest groups that adequate representatives of each conserved. is intended to so as to ensure community are
A study of the pollination biology of the (gyno)dioecious fig, Ficus capreifolia Del. (Moraceae)
(University of the Western Cape, 1994) Naidoo, S.; Baijnath, H.
The pollination biology of Ficus pareidolia Del. was studied. Ficus pareidolia is a (gyno)dioecious species with separate male and female plants bearing male and female syconia respectively. Male syconia had staminate flowers near the ostiolar region of their syconia and numerous short-styled pistillate flowers. Female syconia had only long-styled pistillate flowers throughout their syconia. A mature plant produced up to three hundred syconia. The developmental anatomy of the male and female syconia was studied at both the LM and SEM levels. The structure and development of gall and seed figs appeared to be similar from initiation to the receptive phase. Only female figs, with long-styled pistillate flowers, developed a syntagma and produce seeds. Hermaphrodite (male) figs, with staminate and short-styled pistillate flowers, did not develop a syn-stigma but instead showed early embryo and endosperm development, while also providing only for the development of wasps in their development of b ma le figs are presented. Pollination biology and insects were studied. Female pollinator wasps emerged from the male syconia (gall figs) carrying pollen in their mesothoracic pockets. Coxal combs were also present. Pollination was aerodynamic. Pollen was transferred to short-styled pistillate flowers in the male syconia after oviposition occurred and to long-styled pistillate flowers in the female syconia. Wasps only developed in male syconia, and seeds only developed in female syconia (seed figs). Ratios of gall to uninfected and pollinated to unpollinated flowers are given. Levels of infection of gall flowers varied from 25% to 86%. A single species of secondary psychrophile also oviposited in the gall flowers of male syconia. Of the total number of wasps in each syconium, there were about 70% females of the pollinator wasp, 19,1% males of the pollinator wasp, 8,1% females of the secondary psychrophile, and 2% males of the secondary psychrophile.
Perceptions of first year Biology students at a college of education towards the relevance of population dynamics as prescribed for current biology syllabusses at matriculation level in South African schools
(University of the Western Cape, 1992) Langenhoven, Keith Roy; Mc Kenzie, B; Herman, B
Throughout this research, an attempt has been made to assess the perceived relevance, if any, of the Population Dynamics topic of the standard ten Biology syllabus, especially of those standard ten pupils enrolling as student teachers at a College of Education. From this investigation, various factors, such as lesson methodology, practical field-work and time restraints amongst others, cause most pupils to misconstrue the relevance of Population Dynamics. Recommendations forwarded suggest an in-depth restructuring of the ecology aspects of the Biology courses at College by integrating content acquisition more closely with methodology than is evident at present- This will foster confidence and skills competence in aspirant teachers as they cultivate an environmental ethos in their classrooms. In addition, attention is focused on Energy FIow as a sample topic for transformation from the theoretical to a more relevant and functional approach. In the absence of a definite commitment to the importance of improving teaching and learning methods in the presentation of this topic, most pupils fail to understand the important role of Population Dynamics in a study of Ecology’ against global degradation.
a comparative study of the influence of different copper concentrations on the growth, chemical composition and activities of certain copper containing enzymes in atriplex nummularia lindl. and a. vestita (thunb.) Aell.
(University of the Western Cape, 1990) Green, D H; Aalbers, J
The total amount of native copper in soil depends on the amount of copper in the parent material (Tisdale .et .al.1968). It is usually in greater concentration in the soil than in parent rock because of weathering of the parent rock and the concentration of the element in the upper soil horizons by growing plants. Copper in parent rock exhibits typical chalcopyrite behaviour in that its abundant and stable minerals are sulfides rather than silicates or oxides (Mordtveldt .et .a.J. . 1972). B the most abundant of the copper minerals is which is common in igneous and sedementary rocks. The average ooppe r cxmte e s between 2 to lOOg.m- 3 soil solutions contain about 0.0-lg.m copper ( Devlin 1983). Concentrations higher than this are often regarded as toxic to plants. Two valences of copper are found in naturally occuring compounds i.e. cu+ and cu2 +. The cu 2 + ion is more commonly found in soils, adsorbed to clay minerals or tied up with organic matter.
Population and Physiological Studies of selected Geophytics Species of Lowland Coastal Fynbos in the Southwestern Cape
(University of the Western Cape, 1990) Ruiters, Cornelius; McKenzie, B.
Population and physiological studies were conducted in coastal fynbos in the South-western Cape. Minor ecophysiological studies were also conducted such as the soil moisture content and pH. Two species, viz. Haemanthus pubescens L.f. subspecies fimbriata subspecies Pubescens and Sparaxis grandiflora (de la Roche) Ker. subspecies fimbriata (Lam) Goldbl were selected for the project. H. pubescens subsp. pubescens is a bulbous geophyte belonging to the family Amaryllidaceae and S.grandiflora subsp. fimbriata a cormous geophyte a member of the family Iridaceae. The species were classified either as a perennial geophyte with hysteranthous leaves or an annual geophyte with synathous leaves. Two sites were dermacated on the farm Klein Welmoed at Penhill and near the Blackheath industrial area for the project.

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