subject:(Botany)

University of KwaZulu-Natal

1. Kambatuku, Jack Ratjindua. Ecophysiology of encroaching Acacia mellifera in intra- and inter-specific interactions.

Degree: PhD, Botany, 2010, University of KwaZulu-Natal

► The long-term economic viability and ecological integrity of savanna rangelands is being undermined by increasingly dense woody thickets at the expense of palatable herbaceous cover.… (more)

▼ The long-term economic viability and ecological integrity of savanna rangelands is being undermined by increasingly dense woody thickets at the expense of palatable herbaceous cover. This process is known as shrub- or bush-encroachment. Bush encroachment is a subset of a broader ecological riddle underlying the coexistence of woody and herbaceous vegetation that has been the subject of many ecological models. The ecophysiological mechanisms and interactions between trees and grasses on which most assumptions of ecological models are premised have seldom been tested empirically. This document synthesises the results of greenhouse and field-based investigations of the underlying ecological mechanisms and ecophysiological interactions between encroaching Acacia mellifera trees and grasses in a semi-arid environment. In a greenhouse study, I determined the contribution of N2 fixation to the N-budget of Acacia mellifera under conditions of both varying N availability and competition from grass. Tree seedlings had longer shoots and greater total dry mass in the absence of grass. The leaf δ15N values were lower with grass than without grasses. Thus, trees were more reliant on N2 fixation in the presence of grasses. N2 fixation may enable the tree seedlings to survive competition with grass at critical and vulnerable developmental stages of germination and establishment. In a field removal experiment, I monitored the growth rates, water relations and mortalities of shrubs around which neighbouring woody plants were removed (target) and control shrubs over three years. Results showed target trees to have benefitted from removal of neighbours, which was manifested in significantly faster growth rates, less negative predawn water potential and a relatively small degree of canopy die-back. Nonetheless, neighbouring trees appeared to prevent the whole plant mortalities resulting from severe environmental stress. Growing in close proximity with neighbours could therefore yield positive and negative ecophysiological effects. In another greenhouse experiment, I tested the effects of the separation of moisture uptake with depth between tree seedlings and grasses on two common substrate types. I also examined the influence of repeated grass clipping on the persistence of soil moisture. Results indicated a three-tier rooting pattern with a top layer exclusively exploited by grasses, an intermediate layer occupied by both grass and tree roots and deeper layers exclusively tapped by trees. Tree seedling biomass was negatively affected by grass competition although the biomass of grass was enhanced in the presence of tree seedlings on sandy substrates only. The repeated clipping of grass benefitted tree seedlings on rocky substrate more than it did on sandy substrate. The effects of heavy grazing on soil moisture availability to woody shrubs and thus bush encroachment may be contingent on substrate type, being more acute on rocky terrains. Grass competition suppresses tree seedlings but the removal of grass by grazing weakens this… Advisors/Committee Members: Ward, David Mercer (advisor), Cramer, Michael D (advisor).

Subjects/Keywords: Botany.

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APA (6^th Edition):

Kambatuku, J. R. (2010). Ecophysiology of encroaching Acacia mellifera in intra- and inter-specific interactions. (Doctoral Dissertation). University of KwaZulu-Natal. Retrieved from http://hdl.handle.net/10413/10786

Chicago Manual of Style (16^th Edition):

Kambatuku, Jack Ratjindua. “Ecophysiology of encroaching Acacia mellifera in intra- and inter-specific interactions.” 2010. Doctoral Dissertation, University of KwaZulu-Natal. Accessed February 25, 2020. http://hdl.handle.net/10413/10786.

MLA Handbook (7^th Edition):

Kambatuku, Jack Ratjindua. “Ecophysiology of encroaching Acacia mellifera in intra- and inter-specific interactions.” 2010. Web. 25 Feb 2020.

Vancouver:

Kambatuku JR. Ecophysiology of encroaching Acacia mellifera in intra- and inter-specific interactions. [Internet] [Doctoral dissertation]. University of KwaZulu-Natal; 2010. [cited 2020 Feb 25]. Available from: http://hdl.handle.net/10413/10786.

Council of Science Editors:

Kambatuku JR. Ecophysiology of encroaching Acacia mellifera in intra- and inter-specific interactions. [Doctoral Dissertation]. University of KwaZulu-Natal; 2010. Available from: http://hdl.handle.net/10413/10786

University of KwaZulu-Natal

2. Ghebrehiwot, Habteab Mesghina. The role of fire and fire-related factors on germination and growth of grassland species.

Degree: PhD, Botany, 2010, University of KwaZulu-Natal

URL: http://hdl.handle.net/10413/10826

► Fire, natural or of anthropologic origin is a recurrent phenomenon in South African mesic grasslands. The species composition of these grasslands is sensitive to fire… (more)

▼ Fire, natural or of anthropologic origin is a recurrent phenomenon in South African mesic grasslands. The species composition of these grasslands is sensitive to fire frequency and there exists a permanent fire-species relationship syndrome. The shift follows a general trend where, in the absence of fire for longer periods, the native grass species, possibly the most economically important grass species, give space to relatively less desirable and invasive species accompanied by significant decline in basal cover. Though much is known as to how the floristic composition of the grassland changes in response to fire, the underlying mechanisms responsible for changes in plant vigour and species composition are not fully understood. There exists limited information on germination requirements of the local flora and how recruitment of the species is influenced by fire, fire-related factors and the interaction of these factors among themselves is virtually unknown. Since the discovery by DE LANGE and BOUCHER (1990), plant-derived smoke is being widely studied as an important germination cue and the theme has been the subject of intense experimental research and theoretical work. Germination studies conducted on South African Fynbos, Californian Chaparral, and Australian species have illustrated the widespread ability of plant-derived smoke in promoting germination of species from both fire and non-fire prone habitats. Studies have also showed that plant-derived smoke plays a significant role in vegetative growth of many plants including horticultural and agricultural crops, though mechanisms of smoke action in enhancing germination and promoting plant growth are still under active research. This study sought to gain insight into the role of fire and fire-related cues and other related factors on germination and seedling growth of key grass species from fire-prone grassland in South Africa. In this study, various investigations were conducted on different aspects related to smoke-induced seed germination. Furthermore, in depth examinations were conducted on the effects of fire-related factors such as smoke, heat, soil and nutrients on seed germination and seedling growth of representative key mesic grassland species from South Africa. Laboratory-based germination and vigour experiments were conducted using smoke solutions. The aim was to examine if the strong fire-species relationship syndrome we encounter in post-fire mesic grassland in South Africa is related to the effect of plant-derived smoke on germination and seedling growth. In addition, the interaction of plant-derived smoke solutions with temperature was examined by incubating seeds at a range of temperatures. Treating seeds with smoke-water and butenolide, the germination rate (GR) and final germination percentage (FGP) were greater in 3 of the 6 species. Themeda triandra Forssk. and Tristachya leucothrix Trin. ex Nees showed the greatest response, with final germination increased from 43% to 67% and 35% to 63% respectively. These smoke solutions have also… Advisors/Committee Members: Van Staden, Johannes (advisor), Kirkman, Kevin Peter (advisor).

Subjects/Keywords: Botany.

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APA (6^th Edition):

Ghebrehiwot, H. M. (2010). The role of fire and fire-related factors on germination and growth of grassland species. (Doctoral Dissertation). University of KwaZulu-Natal. Retrieved from http://hdl.handle.net/10413/10826

Chicago Manual of Style (16^th Edition):

Ghebrehiwot, Habteab Mesghina. “The role of fire and fire-related factors on germination and growth of grassland species.” 2010. Doctoral Dissertation, University of KwaZulu-Natal. Accessed February 25, 2020. http://hdl.handle.net/10413/10826.

MLA Handbook (7^th Edition):

Ghebrehiwot, Habteab Mesghina. “The role of fire and fire-related factors on germination and growth of grassland species.” 2010. Web. 25 Feb 2020.

Vancouver:

Ghebrehiwot HM. The role of fire and fire-related factors on germination and growth of grassland species. [Internet] [Doctoral dissertation]. University of KwaZulu-Natal; 2010. [cited 2020 Feb 25]. Available from: http://hdl.handle.net/10413/10826.

Council of Science Editors:

Ghebrehiwot HM. The role of fire and fire-related factors on germination and growth of grassland species. [Doctoral Dissertation]. University of KwaZulu-Natal; 2010. Available from: http://hdl.handle.net/10413/10826

University of KwaZulu-Natal

3. Gold, John David. Cytokinins and the germination of Tagetes minuta L.

Degree: MS, Botany, 2013, University of KwaZulu-Natal

URL: http://hdl.handle.net/10413/10183

► Tagetes minuta L. is a weedy herb that has been a rich source of fragrant oils, used as in the perfume and flavour industry. T.… (more)

▼ Tagetes minuta L. is a weedy herb that has been a rich source of fragrant oils, used as in the perfume and flavour industry. T. minuta achenes germinate erratically under field conditions. However, at the optimal germination temperature of 25 °C, 100 % germination is attained within 48 h of imbibition. The achenes are thermoinhibited at 35 °C. The aims of this project were to assess the role of cytokinins (CKs) in normal germination at 25 °C, and to investigate the factors that regulate thermoinhibition at 35 °C. CKs were extracted from achenes germinating at 25 °C at 0, 24; 48; 96 and 144 h after imbibition. Two different purification techniques were used, namely Dowex cation exchange resin followed by paper chromatography, or high performance liquid chromatography (HPLC). CK-like activity was tested with the soybean callus bioassay. With both techniques, a peak in CK-like activity appeared 24 h after imbibition, which coincides with the period during which most of the achenes germinated. For quantitative analysis, HPLCmass spectrometry (MS) techniques were used. The isoprenoid CKs were far more abundant in T. minuta achenes than the aromatic CKs. cis-Zeatin (cZ) and its derivatives were the most abundant CKs. In total, 19 CK compounds were detected, including 4 free bases and a number of corresponding conjugates. Benzyladenine (BA) was the only aromatic CK detected. There was no common time at which active free base maximal concentrations were detected, suggesting that different CKs may have specific roles in the germination process, and thus peak at different times. This in turn suggests that germination is not a single process, but rather a correlative process involving a number of events, with specific CKs having specific roles relating to these correlative events. There is sufficient evidence obtained from both the soybean callus bioassay and HPLC/MS analysis to suggest that CKs have an active role in T. minuta germination. A decline in free BA during germination without corresponding conjugation, suggests that BA is actively used in early germination processes, possibly in the stimulation of DNA synthesis. Secondly, there was a distinct dihydrozeatin (DHZ) peak obtained at 24 h. Roughly 75 % of the achenes germinate between 16 and 26 h, thus it is likely that DHZ has an active role during the germination of T. minuta. Although CKs are probably not involved in the breaking of dormancy per se, the distinct peak in CK-like activity obtained in the bioassays, 24 h after imbibition, suggests that CKs have an active role in the germination of T. minuta. With respect to the regulation of thermoinhibition, a number of exogenous treatments were applied, including hormones [gibberellins (GA₄₊₇), abscisic acid (ABA), ethylene and a number of CKs], adenosine triphosphate (ATP) and incubation in 100 % oxygen. ABA was extracted from thermoinhibited and germinating achenes to assess the role of ABA in thermoinhibition and germination. While exogenous 0.1 mg L¯¹ GA₄₊₇ application slightly improved normal germination at 25°C,… Advisors/Committee Members: Van Staden, Johannes (advisor), Stirk, Wendy Ann (advisor).

Subjects/Keywords: Botany.

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Gold, J. D. (2013). Cytokinins and the germination of Tagetes minuta L. (Masters Thesis). University of KwaZulu-Natal. Retrieved from http://hdl.handle.net/10413/10183

Chicago Manual of Style (16^th Edition):

Gold, John David. “Cytokinins and the germination of Tagetes minuta L.” 2013. Masters Thesis, University of KwaZulu-Natal. Accessed February 25, 2020. http://hdl.handle.net/10413/10183.

MLA Handbook (7^th Edition):

Gold, John David. “Cytokinins and the germination of Tagetes minuta L.” 2013. Web. 25 Feb 2020.

Vancouver:

Gold JD. Cytokinins and the germination of Tagetes minuta L. [Internet] [Masters thesis]. University of KwaZulu-Natal; 2013. [cited 2020 Feb 25]. Available from: http://hdl.handle.net/10413/10183.

Council of Science Editors:

Gold JD. Cytokinins and the germination of Tagetes minuta L. [Masters Thesis]. University of KwaZulu-Natal; 2013. Available from: http://hdl.handle.net/10413/10183

University of KwaZulu-Natal

4. Nakhooda, Muhammad. The actions of, and interactions between, auxins and cytokinins and their effect on in vitro rooting of selected Eucalyptus clones.

Degree: PhD, Botany, 2011, University of KwaZulu-Natal

URL: http://hdl.handle.net/10413/9759

► Clonal propagation of Eucalyptus spp. and its hybrids allows for competitiveness in the commercial forestry industry through the propagation and preservation of superior/elite genotypes. Vegetative… (more)

▼ Clonal propagation of Eucalyptus spp. and its hybrids allows for competitiveness in the commercial forestry industry through the propagation and preservation of superior/elite genotypes. Vegetative propagation through rooted cuttings is the industry‟s standard and the choice of clones selected for plantations are determined by their rooting ability. However, as many potentially valuable genotypes are recalcitrant to adventitious rooting, micropropagation is the only effective means of propagating them. Micropropagation results in high plantlet yields, achieved primarily through the empirical use of the key plant growth regulators (PGRs) cytokinins and auxins, for shoot and root production, respectively. Their selection for use in vitro is driven by their effects on percent rooting rather than root quality. Little is known regarding the quality of the roots of the plantlets ex vitro, but there is some evidence that they are different from those of seedlings and cuttings. It was therefore hypothesized that the properties of exogenous PGRs and their interaction with other exogenous and endogenous PGRs, influenced root development and subsequent root quality. This was tested in vitro using a good-rooting E. grandis (TAG31) and two poor-rooting E. grandis x nitens hybrid clones (GN155 and NH58). In the former, the auxins supplied during the pre-rooting culture stages (multiplication and elongation) were sufficient for 100% rooting in an auxin-free rooting medium. Different combinations of PGRs in the two pre-rooting stages, followed by rooting without auxins, revealed a direct relationship between the stability of the supplied auxin and the rooting ability of TAG31. Gas chromatographymass spectrometry (GC-MS) analyses indicated that endogenous shoot levels of indole- 3-acetic acid (IAA) influenced graviperception. Also, low IAA content was associated with atypical starch grain accumulation or its absence from root tips (53.1 nmol IAA gˉ¹ DW compared with 325.7 nmol IAA g-¹ DW in gravisensing roots). The specific roles of the natural auxins IAA and IBA on root morphogenesis were then investigated using 2,3,5-triiodobenzoic acid (TIBA; inhibits IAA transport), ρ-chlorophenoxyisobutyric acid (PCIB; inhibits auxin signal transduction), and the auxin antagonist kinetin in the rooting medium, following root induction. After 3 weeks, the mean root diameter was significantly reduced from 552.8μm (control) to 129.2μm (with PCIB) and 278.6μm (with kinetin). TIBA increased root diameter to 833.4μm, decreased Δ root length, increased root vasculature and resulted in agravitropism. Hence, whereas rooting could be induced by IBA, IAA was necessary for the maintenance of vascular integrity and graviperception. This critical role of IAA in root development is of importance as IBA, owing to its higher stability, has been traditionally relied upon for root induction in the majority of micropropagation protocols. The potential of incorporating IAA into the media formulations of in vitro protocols for poor-rooters that do not respond well to… Advisors/Committee Members: Watt, M. Paula (advisor), Mycock, David John (advisor).

Subjects/Keywords: Botany.

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Nakhooda, M. (2011). The actions of, and interactions between, auxins and cytokinins and their effect on in vitro rooting of selected Eucalyptus clones. (Doctoral Dissertation). University of KwaZulu-Natal. Retrieved from http://hdl.handle.net/10413/9759

Chicago Manual of Style (16^th Edition):

Nakhooda, Muhammad. “The actions of, and interactions between, auxins and cytokinins and their effect on in vitro rooting of selected Eucalyptus clones.” 2011. Doctoral Dissertation, University of KwaZulu-Natal. Accessed February 25, 2020. http://hdl.handle.net/10413/9759.

MLA Handbook (7^th Edition):

Nakhooda, Muhammad. “The actions of, and interactions between, auxins and cytokinins and their effect on in vitro rooting of selected Eucalyptus clones.” 2011. Web. 25 Feb 2020.

Vancouver:

Nakhooda M. The actions of, and interactions between, auxins and cytokinins and their effect on in vitro rooting of selected Eucalyptus clones. [Internet] [Doctoral dissertation]. University of KwaZulu-Natal; 2011. [cited 2020 Feb 25]. Available from: http://hdl.handle.net/10413/9759.

Council of Science Editors:

Nakhooda M. The actions of, and interactions between, auxins and cytokinins and their effect on in vitro rooting of selected Eucalyptus clones. [Doctoral Dissertation]. University of KwaZulu-Natal; 2011. Available from: http://hdl.handle.net/10413/9759

University of KwaZulu-Natal

5. Smith, Alain. Niche modelling the distributions of large Acacia nigrescens and Sclerocarya birrea trees.

Degree: MS, Botany, 2011, University of KwaZulu-Natal

URL: http://hdl.handle.net/10413/9758

► MaxEnt modelling uses only the known locations of a species to predict the overall distribution of a species. Large trees are important for the functioning… (more)

▼ MaxEnt modelling uses only the known locations of a species to predict the overall distribution of a species. Large trees are important for the functioning of savanna ecosystems, bringing nutrients to the surface, providing shelter to animals and providing a number of ecological functions. Large trees have been identified as declining in density in many southern African reserves, making the conservation of large trees within reserves an issue in park management, such as in Kruger National Park (KNP) and Hluhluwe iMfolzi Parks (HiP). Two species of primary concern are Acacia nigrescens and Sclerocarya birrea, which have similar distributions in Southern Africa. Effective management of large trees requires understanding their distribution within reserves and any potential distribution changes. By determining the current locations of a species, and using GIS layers of environmental variables to predict the extent of habitats that could support the species, niche models can predict species distribution. Maximum Entropy techniques evaluate the probability of finding the species in raster squares, with values for environmental factors controlling distribution. For this study, the locations of A. nigrescens and S. birrea trees higher than 5 m were recorded in KNP and HiP, and were used in conjunction with MaxEnt to produce distribution probability maps for both species in each reserve. In HiP, the distribution map was compared with an independent existing data set to determine if the predicted distributions were accurate. The factors effecting their distribution were compared between HiP and KNP to determine why the species were found together in KNP but not in HiP. MaxEnt could predict the locations of the species within HiP, but predictions were better for A. nigrescens than S. birrea. In both Reserves, rainfall was the best predictor of tree location, along with elevation. The niche overlap was higher in KNP, where both species are well within their total species range, than in HiP where A. nigrescens was at the edge of its distribution. These variables that are limiting distribution at a reserve scale will have an influence on the overall distribution of the species. Niche models can be used to inform the establishment of botanical reserves or other management strategies that can help preserve large trees within reserves. Advisors/Committee Members: Slotow, Robert H (advisor), Page, Bruce (advisor).

Subjects/Keywords: Botany.

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APA (6^th Edition):

Smith, A. (2011). Niche modelling the distributions of large Acacia nigrescens and Sclerocarya birrea trees. (Masters Thesis). University of KwaZulu-Natal. Retrieved from http://hdl.handle.net/10413/9758

Chicago Manual of Style (16^th Edition):

Smith, Alain. “Niche modelling the distributions of large Acacia nigrescens and Sclerocarya birrea trees.” 2011. Masters Thesis, University of KwaZulu-Natal. Accessed February 25, 2020. http://hdl.handle.net/10413/9758.

MLA Handbook (7^th Edition):

Smith, Alain. “Niche modelling the distributions of large Acacia nigrescens and Sclerocarya birrea trees.” 2011. Web. 25 Feb 2020.

Vancouver:

Smith A. Niche modelling the distributions of large Acacia nigrescens and Sclerocarya birrea trees. [Internet] [Masters thesis]. University of KwaZulu-Natal; 2011. [cited 2020 Feb 25]. Available from: http://hdl.handle.net/10413/9758.

Council of Science Editors:

Smith A. Niche modelling the distributions of large Acacia nigrescens and Sclerocarya birrea trees. [Masters Thesis]. University of KwaZulu-Natal; 2011. Available from: http://hdl.handle.net/10413/9758

University of KwaZulu-Natal

6. Hajari, Elliosha. Development of strategies towards the cryopreservation of germplasm of Ekebergia capensis Sparrm. : an indigenous species that produces recalcitrant seeds.

Degree: PhD, Botany, 2011, University of KwaZulu-Natal

URL: http://hdl.handle.net/10413/9763

► The conservation of germplasm of indigenous plant species is vital not only to preserve valuable genotypes, but also the diversity represented by the gene pool.… (more)

▼ The conservation of germplasm of indigenous plant species is vital not only to preserve valuable genotypes, but also the diversity represented by the gene pool. A complicating factor, however, is that a considerable number of species of tropical and sub-tropical origin produce recalcitrant or otherwise non-orthodox seeds. Such seeds are hydrated and metabolically active when shed and cannot be stored under conventional conditions of low temperature and low relative humidity. This poses major problems for the longterm conservation of the genetic resources of such species. Presently, the only strategy available for the long-term conservation of species that produce recalcitrant seeds is cryopreservation. Ekebergia capensis is one such indigenous species that produces recalcitrant seeds. The aim of the present study was to develop methods for the cryopreservation of germplasm of this species. Different explant types were investigated for this purpose, viz. embryonic axes (with attached cotyledonary segments) excised from seeds, and two in vitro-derived explants, i.e. ‘broken’ buds excised from in vitro-germinated seedlings and adventitious shoots generated from intact in vitro-germinated roots. Suitable micropropagation protocols were developed for all explant types prior to any other experimentation. Before explants could be cryopreserved it was necessary to reduce their water content in order to limit damaging ice crystallisation upon cooling. All explants tolerated dehydration (by flash drying) to 0.46 – 0.39 g gˉ¹ water content (dry mass basis) with survival ranging from 100 – 80%, depending on the explant. In addition, penetrating and non-penetrating cryoprotectants were used to improve cryo-tolerance of explants. The cryoprotectants tested were sucrose, glycerol, DMSO and a combination of sucrose and glycerol. Explant survival following cryoprotection and dehydration ranged from 100 – 20%. Cryoprotected and dehydrated explants were exposed to cryogenic temperatures by cooling at different rates, since this factor is also known to affect the success of a cryopreservation protocol. The results showed that ‘broken’ buds could not tolerate cryogen exposure. This was likely to have been a consequence of the large size of explants and their originally highly hydrated condition. Adventitious shoots tolerated cryogenic exposure slightly better with 7 – 20% survival after cooling in sub-cooled nitrogen. Limited shoot production (up to 10%) was obtained when axes with attached cotyledonary segments were exposed to cryogenic temperatures. In contrast, root production from axes cooled in sub-cooled nitrogen remained high (67 – 87%). Adventitious shoots were subsequently induced on roots generated from cryopreserved axes by applying a protocol developed to generate adventitious shoots on in vitrogerminated roots. In this manner, the goal of seedling establishment from cryopreserved axes was attained. Each stage of a cryopreservation protocol imposes stresses that may limit success. To gain a better understanding of these… Advisors/Committee Members: Berjak, Patricia (advisor).

Subjects/Keywords: Botany.

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Hajari, E. (2011). Development of strategies towards the cryopreservation of germplasm of Ekebergia capensis Sparrm. : an indigenous species that produces recalcitrant seeds. (Doctoral Dissertation). University of KwaZulu-Natal. Retrieved from http://hdl.handle.net/10413/9763

Chicago Manual of Style (16^th Edition):

Hajari, Elliosha. “Development of strategies towards the cryopreservation of germplasm of Ekebergia capensis Sparrm. : an indigenous species that produces recalcitrant seeds.” 2011. Doctoral Dissertation, University of KwaZulu-Natal. Accessed February 25, 2020. http://hdl.handle.net/10413/9763.

MLA Handbook (7^th Edition):

Hajari, Elliosha. “Development of strategies towards the cryopreservation of germplasm of Ekebergia capensis Sparrm. : an indigenous species that produces recalcitrant seeds.” 2011. Web. 25 Feb 2020.

Vancouver:

Hajari E. Development of strategies towards the cryopreservation of germplasm of Ekebergia capensis Sparrm. : an indigenous species that produces recalcitrant seeds. [Internet] [Doctoral dissertation]. University of KwaZulu-Natal; 2011. [cited 2020 Feb 25]. Available from: http://hdl.handle.net/10413/9763.

Council of Science Editors:

Hajari E. Development of strategies towards the cryopreservation of germplasm of Ekebergia capensis Sparrm. : an indigenous species that produces recalcitrant seeds. [Doctoral Dissertation]. University of KwaZulu-Natal; 2011. Available from: http://hdl.handle.net/10413/9763

University of KwaZulu-Natal

7. Rice, Laura Jane. Micropropagation of Brunsvigia undulata F.M. Leight.

Degree: MS, Botany, 2009, University of KwaZulu-Natal

URL: http://hdl.handle.net/10413/804

► Many South African medicinal plants face the threat of over-collection for use in traditional medicines. Many bulbous plants suffer as the whole plant is removed… (more)

▼ Many South African medicinal plants face the threat of over-collection for use in traditional medicines. Many bulbous plants suffer as the whole plant is removed from the wild so that the bulb may be used for medicine. Micropropagation is a technique which can be used as an alternative to conventional propagation methods. Micropropagation produces many plantlets in a relatively short period of time. Different plant parts of Brunsvigia undulata F.M. Leight, a rare South African species of medicinal value, were used in an attempt to produce in vitro plantlets using micropropagation techniques. Although leaf and floral explants were successfully formed from seedling explants and twin-scales. Seeds germinated quickly in culture. Seedlings which grew from seeds were cut into sections and used to initiate bulblets. Seedling explants formed bulblets, shoots and callus best when the explants included a meristematic region. Callus from seedling explants formed shoot clusters readily when placed on hormone-free MURASHIGE and SKOOG (1962) (MS) medium. Shoots from shoot clusters formed bulblets and rooted on medium supplemented with IBA. The greatest rooting response was achieved by bulblets on 1 mgl-1 IBA. The callus which was left after shoot clusters were separated was placed back onto hormone-free MS medium. Callus explants continued to form shoot clusters. Twin-scales, cut from large parent bulbs, were cultured on 25 hormone treatments. Bulblets formed on twin-scales even in the absence of plant growth hormones. Bulblets formed by twin-scales were used to determine the effects of both medium constituents and environmental factors on bulblet multiplication. Bulblet multiplication was greatest when bulblets were split in half and cultured as half-bulblets. Optimal multiplication was achieved on hormone-free MS, with 4% sucrose, kept at high temperatures in the dark. Bulblets were successfully initiated and multiplied from both seedlings and twin-scales. Bulblets which were produced via both protocols were acclimatized relatively easily. Both explant types could be used to mass propagate Brunsvigia undulata. Advisors/Committee Members: Finnie, Jeffrey Franklin (advisor), Van Staden, Johannes (advisor).

Subjects/Keywords: Botany.

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Rice, L. J. (2009). Micropropagation of Brunsvigia undulata F.M. Leight. (Masters Thesis). University of KwaZulu-Natal. Retrieved from http://hdl.handle.net/10413/804

Chicago Manual of Style (16^th Edition):

Rice, Laura Jane. “Micropropagation of Brunsvigia undulata F.M. Leight.” 2009. Masters Thesis, University of KwaZulu-Natal. Accessed February 25, 2020. http://hdl.handle.net/10413/804.

MLA Handbook (7^th Edition):

Rice, Laura Jane. “Micropropagation of Brunsvigia undulata F.M. Leight.” 2009. Web. 25 Feb 2020.

Vancouver:

Rice LJ. Micropropagation of Brunsvigia undulata F.M. Leight. [Internet] [Masters thesis]. University of KwaZulu-Natal; 2009. [cited 2020 Feb 25]. Available from: http://hdl.handle.net/10413/804.

Council of Science Editors:

Rice LJ. Micropropagation of Brunsvigia undulata F.M. Leight. [Masters Thesis]. University of KwaZulu-Natal; 2009. Available from: http://hdl.handle.net/10413/804

University of KwaZulu-Natal

8. Rodger, James Gordon. Consequences of self-fertilisation for fecundity and progeny performance in invasive plants.

Degree: PhD, Botany, 2013, University of KwaZulu-Natal

URL: http://hdl.handle.net/10413/9863

► Plants that can self-fertilise should, on average, be more invasive than plants that can not self-fertilise because they can reproduce regardless of the availability of… (more)

▼ Plants that can self-fertilise should, on average, be more invasive than plants that can not self-fertilise because they can reproduce regardless of the availability of mates and pollinators. Self-fertilisation should have a strong effect on invasiveness because, to become invasive, introduced plants have to pass through bottlenecks of low plant abundance when mates and pollinators are likely to be scarce. Under these conditions, reproduction of plants that can not self-fertilise is often limited by pollen receipt. Selfing may thus contribute to invasiveness by alleviating pollen limitation Allee effects (pollen limitation caused by low abundance) especially as theoretical work indicates that ability to invade and rate of invasion are highly sensitive to fecundity of small and isolated populations and single individuals. Recently, a correlation between ability to self-fertilise and invasiveness has been observed in several invasive floras, consistent with the hypothesis that species that can self-fertilise should be more invasive. However, it has not yet been demonstrated that this relationship arises from reproductive assurance. To establish the causal basis of a correlation between a plant trait and invasiveness, a mechanism linking that trait to invasiveness must be demonstrated. For this it is necessary to show firstly that the trait actually affects performance in the introduced range and secondly that plant performance affects invasiveness. Self-fertilisation is hypothesised to increase invasiveness by enhancing reproductive performance. The first step in testing this hypothesis is therefore to show that being able to self-fertilise increases fecundity, i.e. that it provides reproductive assurance. However, progeny from self-fertilisation often suffer from inbreeding depression – they perform worse than those from cross-fertilisation – so it is also necessary to show that this cost does not outweigh the reproductive assurance benefit of selfing. So far, reproductive assurance has been assessed in only a few invasive plant species. These studies did not assess inbreeding depression and only one investigated reproductive assurance in relation to abundance, finding no relationship. In this thesis I have sought to understand the importance of self-fertilisation for reproduction of invasive plants in the introduced range through case studies. In particular, I assessed whether reproductive assurance from self-fertilization alleviates Allee effects via pollen limitation. To do this I tested whether pollen limitation and reproductive assurance were greater at low plant abundance. Further, I conducted progeny trials to assess inbreeding depression, as this cost of selfing potentially negates reproductive assurance benefits. I also conducted observations and experiments to identify the principle pollinators of my study species as reproductive assurance and its relationship to plant abundance depend on pollinator visitation, The Australian trees Acacia mearnsii and A. dealbata are highly invasive in the study region of… Advisors/Committee Members: Johnson, Steven D (advisor), Van Kleunen, Mark (advisor).

Subjects/Keywords: Botany.

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APA (6^th Edition):

Rodger, J. G. (2013). Consequences of self-fertilisation for fecundity and progeny performance in invasive plants. (Doctoral Dissertation). University of KwaZulu-Natal. Retrieved from http://hdl.handle.net/10413/9863

Chicago Manual of Style (16^th Edition):

Rodger, James Gordon. “Consequences of self-fertilisation for fecundity and progeny performance in invasive plants.” 2013. Doctoral Dissertation, University of KwaZulu-Natal. Accessed February 25, 2020. http://hdl.handle.net/10413/9863.

MLA Handbook (7^th Edition):

Rodger, James Gordon. “Consequences of self-fertilisation for fecundity and progeny performance in invasive plants.” 2013. Web. 25 Feb 2020.

Vancouver:

Rodger JG. Consequences of self-fertilisation for fecundity and progeny performance in invasive plants. [Internet] [Doctoral dissertation]. University of KwaZulu-Natal; 2013. [cited 2020 Feb 25]. Available from: http://hdl.handle.net/10413/9863.

Council of Science Editors:

Rodger JG. Consequences of self-fertilisation for fecundity and progeny performance in invasive plants. [Doctoral Dissertation]. University of KwaZulu-Natal; 2013. Available from: http://hdl.handle.net/10413/9863

University of KwaZulu-Natal

9. Bairu, Michael Wolday. Plant growth regulators and somaclonal variation in Cavendish banana (Musa AAA cv. Zelig).

Degree: MS, Botany, 2013, University of KwaZulu-Natal

URL: http://hdl.handle.net/10413/9849

► Cavendish bananas are the most important sub-group of all bananas. They includes more than 30% of the global banana production and almost all bananas exported… (more)

▼ Cavendish bananas are the most important sub-group of all bananas. They includes more than 30% of the global banana production and almost all bananas exported are of the Cavendish type. This sub-group is also an important food source. Most of the fruit is consumed locally, such that only 35% enters the international market. To meet the regular demand for domestic consumption and market supply there must be a reliable production strategy. The technique of tissue culture is a better option than conventional propagation techniques. However. the high incidence of somaclonal variation among plants derived from tissue culture is a problem for commercial producers. Several factors such as genotype, tissue source, duration in culture, and the tissue culture technique employed, cause somaclonal variation. The impact of plant growth regulators on somaclonal variation was studied on Cavendish banana cv. 'Zelig' obtained from African Biotechnologies Ltd., South Africa. In vitro grown plants at the 4th multiplication cycle were supplied for the investigation. The first component of the investigation dealt with the effect of types of plant growth regulators. Combinations of the auxins IAA, IBA and NAA with the cytokinins BA and TDZ were used to culture the plants for ten multiplication cycles. Plants were then randomly selected to collect leaf material for DNA extraction and RAPD analysis. The second aim of this study was to investigate the effect of the cytokinin BA on plantlets subcultured over 5-10 multiplication cycles. The auxin IAA at the concentration of 2 mgl-1 was combined with BA at concentrations of 2.5, 5.0 and 7.5 mgl-1. Plants were analyzed at each level of subculture from the 5th to the 10th cycle for respective cytokinin concentrations. Plants were then randomly selected for the collection of leaf material for DNA extraction and RAPD analysis. DNA was extracted from leaf tissue of in vitro grown plants using a modified CTAB extraction procedure. DNA amplification products were scored for the presence and absence of bands in a particular locus. Results were clustered according to their similarities. The relationship between multiplication rate and variation was assessed using correlation analysis. Results of the investigation showed that treatments with higher multiplication rates produced higher rates of variation. A variation rate of 55% was recorded for treatments containing IAA and BA. A higher rate of variation (72%) was identified in the treatment with IAA (2mgl-1) plus BA (7.5 mgl-1) over 10 cycles. In all cases the dwarf off-type was the most common type of variant obtained, contributing 87.7% of the total amount of variation. The dwarf specific marker (OPJ-041500) reported previously in Williams Cavendish was identified in cv. 'Zelig' in this study. Another band similar in size was amplified by primer OPC-15 and named OPC-151500 . This band consistently appeared in all the normal plants and was absent in all the dwarf types and hence could be used as a dwarf specific marker. Advisors/Committee Members: Van Staden, Johannes (advisor), Fennell, Catherine W (advisor).

Subjects/Keywords: Botany.

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APA (6^th Edition):

Bairu, M. W. (2013). Plant growth regulators and somaclonal variation in Cavendish banana (Musa AAA cv. Zelig). (Masters Thesis). University of KwaZulu-Natal. Retrieved from http://hdl.handle.net/10413/9849

Chicago Manual of Style (16^th Edition):

Bairu, Michael Wolday. “Plant growth regulators and somaclonal variation in Cavendish banana (Musa AAA cv. Zelig).” 2013. Masters Thesis, University of KwaZulu-Natal. Accessed February 25, 2020. http://hdl.handle.net/10413/9849.

MLA Handbook (7^th Edition):

Bairu, Michael Wolday. “Plant growth regulators and somaclonal variation in Cavendish banana (Musa AAA cv. Zelig).” 2013. Web. 25 Feb 2020.

Vancouver:

Bairu MW. Plant growth regulators and somaclonal variation in Cavendish banana (Musa AAA cv. Zelig). [Internet] [Masters thesis]. University of KwaZulu-Natal; 2013. [cited 2020 Feb 25]. Available from: http://hdl.handle.net/10413/9849.

Council of Science Editors:

Bairu MW. Plant growth regulators and somaclonal variation in Cavendish banana (Musa AAA cv. Zelig). [Masters Thesis]. University of KwaZulu-Natal; 2013. Available from: http://hdl.handle.net/10413/9849

University of KwaZulu-Natal

10. Cheesman, Lee. Micropropagation and pharmacological evaluation of Boophone disticha.

Degree: PhD, Botany, 2013, University of KwaZulu-Natal

URL: http://hdl.handle.net/10413/9919

► Boophone disticha (L.f.) Herb is one of the most widely distributed bulbous species in southern Africa. Of Africa’s many bulbous plants, it is widely known… (more)

▼ Boophone disticha (L.f.) Herb is one of the most widely distributed bulbous species in southern Africa. Of Africa’s many bulbous plants, it is widely known for its poisonous and medicinal properties. It is of considerable ethnobotanical interest in traditional medicine because of its hallucinogenic alkaloids and it has great potential as an ornamental due to its fan-shaped foliage and large umbel of bright pink to deep red flowers. In South Africa, many bulbous plants are used in traditional medicine which are collected from wild populations. The high demand for trade and use of such plants, that are destructively harvested, places an enormous pressure on natural populations. According to the Red List of South African Plants, the conservation status of B. disticha has been listed as ‘declining’. It is, therefore, important to develop conservation strategies for these medicinal plants, such as the development of alternative propagation methods. Micropropagation is a useful technique for rapid clonal multiplication of plant material which could alleviate the pressure on the wild plant populations, as well as potentially producing useful secondary metabolites. The in vitro induction of storage organs is especially beneficial as it can limit the loss of plants during acclimatization since bulblets are generally hardier than shoots or plantlets. Thus, the main aim of this research was to establish a micropropagation protocol which could be a valuable tool for conservation of this plant species. In addition, B. disticha plants were assessed in various ethnopharmacological assays to evaluate their medicinal properties, and a preliminary study on the population genetics was also conducted. As part of the development of a suitable micropropagation protocol, the effect of environmental and physiological factors on the initiation and growth of bulblets were investigated. These factors included the effect of various plant growth regulators, carbohydrates, temperature, photoperiod and liquid culture. Different explants (i.e. ovaries, anthers, filaments, pedicels, embryos, seeds and bulb twin-scales) were tested to determine which explants were the most suitable for subsequent experiments. Although success was limited, twin-scales proved to be the most suitable explant and it was demonstrated that activated charcoal, ascorbic acid and N6- benzyladenine were required as media supplements. Antimicrobial activity was tested between different plant parts and seasons. The plant parts (roots, leaves, outer and inner bulb scales) were extracted with a range of differing polarity solvents. These were screened for antibacterial activity against Bacillus subtilis, Staphylococcus aureus, Escherichia coli and Klebsiella pneumoniae, and for antifungal activity against Candida albicans. Extracts from roots of plants collected in spring and summer showed the best antimicrobial activity against B. subtilis, E. coli and K. pneumoniae, indicating that plant part and collection time do affect activity. In vitro grown bulblets also showed… Advisors/Committee Members: Van Staden, Johannes (advisor), Finnie, Jeffrey Franklin (advisor), Light, Marnie Elizabeth (advisor).

Subjects/Keywords: Botany.

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Cheesman, L. (2013). Micropropagation and pharmacological evaluation of Boophone disticha. (Doctoral Dissertation). University of KwaZulu-Natal. Retrieved from http://hdl.handle.net/10413/9919

Chicago Manual of Style (16^th Edition):

Cheesman, Lee. “Micropropagation and pharmacological evaluation of Boophone disticha.” 2013. Doctoral Dissertation, University of KwaZulu-Natal. Accessed February 25, 2020. http://hdl.handle.net/10413/9919.

MLA Handbook (7^th Edition):

Cheesman, Lee. “Micropropagation and pharmacological evaluation of Boophone disticha.” 2013. Web. 25 Feb 2020.

Vancouver:

Cheesman L. Micropropagation and pharmacological evaluation of Boophone disticha. [Internet] [Doctoral dissertation]. University of KwaZulu-Natal; 2013. [cited 2020 Feb 25]. Available from: http://hdl.handle.net/10413/9919.

Council of Science Editors:

Cheesman L. Micropropagation and pharmacological evaluation of Boophone disticha. [Doctoral Dissertation]. University of KwaZulu-Natal; 2013. Available from: http://hdl.handle.net/10413/9919

University of KwaZulu-Natal

11. Nigro, Sara Anna. Genetic modification in Pinus patula using transgenic technology.

Degree: PhD, Botany, 2006, University of KwaZulu-Natal

URL: http://hdl.handle.net/10413/10053

► Progress in tree biotechnology initially trailed behind agricultural crops due to their long life cycle, difficult tissue culture and regeneration protocols, and their abundance in… (more)

▼ Progress in tree biotechnology initially trailed behind agricultural crops due to their long life cycle, difficult tissue culture and regeneration protocols, and their abundance in natural forests. However, rapid global deforestation rates, together with an increased world demand for pulp, paper and timber products, have prompted scientific and commercial focus to improve genetic timber stocks. South Africa, a tree-poor country (where indigenous forests are protected), has relied almost solely on exotic plantations to meet its demand for timber. A pioneer study investigating the feasibility of using direct (biolistic) and indirect (Agrobacterium-mediated) methods for gene transfer was undertaken in Pinus patula Schiede et Deppe, a Mexican softwood and a forerunner for saw timber, pulpwood and paper in the South African forest industries. The aim of the transformation methods was to impart herbicide resistance to the trees. This was achieved via the introduction of a bar-GUS pAHC25 cassette under the control of the ubiquitin promoter. To provide target material for transformation, two in vitro micropropagation pathways were used: somatic embryogenesis and organogenesis. Both embryonal suspensor masses (ESM) and somatic embryos at various stages of development were initially used as target explants for the biolistic study using an established in vitro protocol. A stepwise selection was implemented in order to allow transformed (particularly bombarded) cultures the opportunity to regenerate under selection pressure using MSG3 maintenance medium supplemented with BASTA® herbicide at 1 mg l ¯¹ followed by 3 mg l¯¹ active ingredient at the next subculture. Biolistic transgene delivery was more efficient when sorbitol was included in the pre-bombardment medium enabling use of higher vacuum and shooting pressures, without lowering the regeneration potential of ESM significantly. Bombarded material from two genotypes (Lines 2 and 3) was regenerated to produce mature somatic embryos using an optimized regeneration regimen. The indirect study with Agrobacterium tumefaciens (LBA4404), transformed with the pAHC25 vector via triparental mating or heat shock, used a variety of target tissues including: mature somatic embryos, ESM and mature zygotic embryos (MZE's) - a novel in vitro system for P. patula. The Agrobacterium-mediated method resulted in optimized decontamination conditions using a combination of liquid MSG3 (or sterile dH₂O for mature embryos) supplemented with 500 mg l ¯¹ cefotaxime, with rotation, and sterile 65 mm Whatman No. 3 filter paper stacks, which avoided excess filtering and stress to transformation material. Further efforts to aid regeneration during the indirect study included L-proline post-transformation, though no mature somatic embryos were regenerated at the conclusion of the Agrobacterium-mediated study. Recovery of transformed ESM in both studies was best during the active growth phase 4-6 d after subculture. Regeneration with good somatic embryo potential was an exigent aspect in both… Advisors/Committee Members: Van Staden, Johannes (advisor), Makunga, Nokwanda P (advisor), Jones, N. B (advisor).

Subjects/Keywords: Botany.

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Nigro, S. A. (2006). Genetic modification in Pinus patula using transgenic technology. (Doctoral Dissertation). University of KwaZulu-Natal. Retrieved from http://hdl.handle.net/10413/10053

Chicago Manual of Style (16^th Edition):

Nigro, Sara Anna. “Genetic modification in Pinus patula using transgenic technology.” 2006. Doctoral Dissertation, University of KwaZulu-Natal. Accessed February 25, 2020. http://hdl.handle.net/10413/10053.

MLA Handbook (7^th Edition):

Nigro, Sara Anna. “Genetic modification in Pinus patula using transgenic technology.” 2006. Web. 25 Feb 2020.

Vancouver:

Nigro SA. Genetic modification in Pinus patula using transgenic technology. [Internet] [Doctoral dissertation]. University of KwaZulu-Natal; 2006. [cited 2020 Feb 25]. Available from: http://hdl.handle.net/10413/10053.

Council of Science Editors:

Nigro SA. Genetic modification in Pinus patula using transgenic technology. [Doctoral Dissertation]. University of KwaZulu-Natal; 2006. Available from: http://hdl.handle.net/10413/10053

University of KwaZulu-Natal

12. Light, Marnie Elizabeth. An investigation of the medicinal properties of Siphonochilus aethiopicus.

Degree: MS, Botany, 2013, University of KwaZulu-Natal

URL: http://hdl.handle.net/10413/10184

► Siphonochilus aethiopicus (Schweinf.) B.L. Burtt (Zingiberaceae), commonly known as wild ginger, is a highly sought after plant for use in traditional medicine in South Africa.… (more)

▼ Siphonochilus aethiopicus (Schweinf.) B.L. Burtt (Zingiberaceae), commonly known as wild ginger, is a highly sought after plant for use in traditional medicine in South Africa. Over-exploitation of this medicinal plant has resulted in regional extinction in the wild. As a result, there is great interest in the medicinal properties of S. aethiopicus, and as a plant for small scale cultivation to increase the supply for use in traditional medicine. Water, ethanol and ethyl acetate extracts were prepared from the leaves, rhizomes and roots of S. aethiopicus. These extracts were tested for in vitro anti-inflammatory activity in the cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2) assays, and in the microdilution antibacterial assay. The aqueous extracts showed no significant prostaglandin synthesis inhibition in the COX-1 and COX-2 assays. The ethanol and ethyl acetate extracts of the leaves showed the highest levels of activity at a concentration of 250 µg ml¯¹ per test solution, in both the COX-1 and COX-2 assays. The ethanol and ethyl acetate extracts of the rhizomes and roots also had moderate levels of activity in the COX-1 assay. These results provide some evidence for the rational use of S. aethiopicus in traditional medicine for anti-inflammatory purposes. In the microdilution antibacterial assay, no inhibitory activity against the test bacteria was detected with the aqueous extracts. The ethanol and ethyl acetate extracts tested showed greater antibacterial activity at minimal inhibitory concentrations ranging from 0.78 to 3.13 mg ml¯¹ against the gram-positive bacteria (Bacillus subtilis, Staphylococcus aureus) than the Gram-negative bacteria (Escherichia coli, Klebsiella pneumoniae). No distinct differences were observed between the ethanol and ethyl acetate extracts, or between the different plant parts. A serial extraction of S. aethiopicus rhizome material was conducted and the extracts were tested in the COX-1 assay and the microdilution assay as a preliminary investigation for a bulk extraction. The hexane and ethyl acetate extracts gave slightly higher COX-1 inhibition than the ethanol extract. No distinct differences were observed in the microdilution assay. A bulk ethyl acetate extract of S. aethiopicus rhizome material was prepared, yielding 6.3 g of a thin orange oil. Vacuum liquid chromatography (VLC) was used to fractionate ≈4 g of the extract. The VLC fractions were evaluated using thin layer chromatography (TLC) and a bioautographic assay, using S. aureus as a test organism. The fractions were also tested in the COX-1 assay. The bioautography revealed a number of compounds which exhibited antibacterial activity. Fraction C was purified further using preparative TLC, and 24.9 mg of a pure compound from R,0.54 (toluene:ethyl acetate 93:7) was isolated. The structure of the compound was elucidated from nuclear magnetic resonance (NMR) spectra, and mass spectroscopy of the compound was also recorded. The compound was identified as the sesquiterpenoid furanoeremophil-2-en-1-one, which is… Advisors/Committee Members: Van Staden, Johannes (advisor), Jager, Anna K (advisor).

Subjects/Keywords: Botany.

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Light, M. E. (2013). An investigation of the medicinal properties of Siphonochilus aethiopicus. (Masters Thesis). University of KwaZulu-Natal. Retrieved from http://hdl.handle.net/10413/10184

Chicago Manual of Style (16^th Edition):

Light, Marnie Elizabeth. “An investigation of the medicinal properties of Siphonochilus aethiopicus.” 2013. Masters Thesis, University of KwaZulu-Natal. Accessed February 25, 2020. http://hdl.handle.net/10413/10184.

MLA Handbook (7^th Edition):

Light, Marnie Elizabeth. “An investigation of the medicinal properties of Siphonochilus aethiopicus.” 2013. Web. 25 Feb 2020.

Vancouver:

Light ME. An investigation of the medicinal properties of Siphonochilus aethiopicus. [Internet] [Masters thesis]. University of KwaZulu-Natal; 2013. [cited 2020 Feb 25]. Available from: http://hdl.handle.net/10413/10184.

Council of Science Editors:

Light ME. An investigation of the medicinal properties of Siphonochilus aethiopicus. [Masters Thesis]. University of KwaZulu-Natal; 2013. Available from: http://hdl.handle.net/10413/10184

University of KwaZulu-Natal

13. Chukwujekwu, Jude Chinedu. A pharmacological study of some Nigerian medicinal plants.

Degree: PhD, Botany, 2013, University of KwaZulu-Natal

URL: http://hdl.handle.net/10413/10196

► Petroleum ether, dichloromethane, and 80% ethanol extracts of 15 plant species collected in Nigeria were screened for in vitro antibacterial, anti-inflammatory and antimalarial activities. Antibacterial… (more)

▼ Petroleum ether, dichloromethane, and 80% ethanol extracts of 15 plant species collected in Nigeria were screened for in vitro antibacterial, anti-inflammatory and antimalarial activities. Antibacterial activity was tested using the agar diffusion method, while the minimum inhibitory concentrations (MIC) of the active extracts were determined using the microtitre serial dilution method. Most antibacterial activity detected was against Gram-positive bacteria with Staphylococcus aureus being the most susceptible. The highest activity was found in petroleum ether and dichloromethane leaf extracts of Mallotus oppositifolius; petroleum ether, dichloromethane and ethanolic root extracts of Newbouldia laevis; and ethanolic root extracts of Morinda lucida and Canthium subcordatum. Against the Gram-negative bacterium Escherichia coli, the highest activity was found in dichloromethane leaf extracts of Newbouldia laevis, ethanolic root extracts of Phyllanthus amarus, Mallotus oppositifolius, and Canthium subcordatum. A total of 60 plant extracts were screened for antiplasmodial activity. A chloroquine sensitive strain of Plasmodium falciparum (D10) was used. In the assay, the parasite lactate dehydrogenase (pLDH) activity was used to measure parasite viability. About 11 extracts showed promising activity with an IC₅₀ ranging from 2.5 to 13.4 µg/ml. The petroleum ether leaf extract of Hyptis suaveolens had the highest activity (IC₅₀ = 2.5 µg/ml). The cyclooxygenase (COX-1 and COX-2) assays were used to test for anti-inflammatory activity. All the plant species, with the exception of Hedranthera barteri and Picralima nitida showed anti-inflammatory activity. Apart for a few ethanolic extracts, all the activities were recorded with petroleum ether and dichloromethane extracts. Employing bioassay-guided activity fractionation, an antibacterial anthraquinone identified as emodin was isolated from ethanolic root extract of Senna occidentalis. Although this compound had been isolated from other sources, this was the first report of isolation from Senna occidentalis. Using a similar approach a novel antimalarial diterpenoid was isolated from the petroleum ether leaves extract of Hyptis suaveolens. It had IC₅₀ of 0.1 µg/ml. This new compound is worthy of further investigation and may act as an important lead compound for future antimalarial drugs. Advisors/Committee Members: Van Staden, Johannes (advisor).

Subjects/Keywords: Botany.

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Chukwujekwu, J. C. (2013). A pharmacological study of some Nigerian medicinal plants. (Doctoral Dissertation). University of KwaZulu-Natal. Retrieved from http://hdl.handle.net/10413/10196

Chicago Manual of Style (16^th Edition):

Chukwujekwu, Jude Chinedu. “A pharmacological study of some Nigerian medicinal plants.” 2013. Doctoral Dissertation, University of KwaZulu-Natal. Accessed February 25, 2020. http://hdl.handle.net/10413/10196.

MLA Handbook (7^th Edition):

Chukwujekwu, Jude Chinedu. “A pharmacological study of some Nigerian medicinal plants.” 2013. Web. 25 Feb 2020.

Vancouver:

Chukwujekwu JC. A pharmacological study of some Nigerian medicinal plants. [Internet] [Doctoral dissertation]. University of KwaZulu-Natal; 2013. [cited 2020 Feb 25]. Available from: http://hdl.handle.net/10413/10196.

Council of Science Editors:

Chukwujekwu JC. A pharmacological study of some Nigerian medicinal plants. [Doctoral Dissertation]. University of KwaZulu-Natal; 2013. Available from: http://hdl.handle.net/10413/10196

University of KwaZulu-Natal

14. Rambuda, Tendani Dennis. Pollination and breeding systems of alien invasive plants in KwaZulu - Natal in South Africa.

Degree: MS, Botany, 2014, University of KwaZulu-Natal

URL: http://hdl.handle.net/10413/10375

► According to Baker (1955), success of plant invasions can be attributed to autogamous breeding systems and generalist pollination systems. A test of Baker's rule was… (more)

Subjects/Keywords: Botany.

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APA (6^th Edition):

Rambuda, T. D. (2014). Pollination and breeding systems of alien invasive plants in KwaZulu - Natal in South Africa. (Masters Thesis). University of KwaZulu-Natal. Retrieved from http://hdl.handle.net/10413/10375

Chicago Manual of Style (16^th Edition):

Rambuda, Tendani Dennis. “Pollination and breeding systems of alien invasive plants in KwaZulu - Natal in South Africa.” 2014. Masters Thesis, University of KwaZulu-Natal. Accessed February 25, 2020. http://hdl.handle.net/10413/10375.

MLA Handbook (7^th Edition):

Rambuda, Tendani Dennis. “Pollination and breeding systems of alien invasive plants in KwaZulu - Natal in South Africa.” 2014. Web. 25 Feb 2020.

Vancouver:

Rambuda TD. Pollination and breeding systems of alien invasive plants in KwaZulu - Natal in South Africa. [Internet] [Masters thesis]. University of KwaZulu-Natal; 2014. [cited 2020 Feb 25]. Available from: http://hdl.handle.net/10413/10375.

Council of Science Editors:

Rambuda TD. Pollination and breeding systems of alien invasive plants in KwaZulu - Natal in South Africa. [Masters Thesis]. University of KwaZulu-Natal; 2014. Available from: http://hdl.handle.net/10413/10375

University of KwaZulu-Natal

15. Cook, Elizabeth Louise. The senescence of the cut carnation (Dianthus caryophyllus L. cv. White Sim) flower.

Degree: PhD, Botany, 2014, University of KwaZulu-Natal

URL: http://hdl.handle.net/10413/10529

► A review of the literature pertaining to cut carnation flower senescence and the regulatory role of plant hormones in this process revealed the value of… (more)

▼ A review of the literature pertaining to cut carnation flower senescence and the regulatory role of plant hormones in this process revealed the value of this system in physiological studies. Carnation flower senescence is a good example of correlative senescence and therefore this final development stage involves an interaction between flower parts dying at the expense of the development of others. Due to the survival value of the seed, ovary growth occurs to the detriment of the surrounding flower parts especially the petals, the flower part that determines vaselife. This senescence strategy occurs, although at a later stage, even when pollination is unsuccessful. Additional ethylene applied using 2-chloroethyl phosphonic acid, which when incorporated into plant tissue produces ethylene, accelerated carnation flower senescence. If the carnation flowers are treated with silver thiosulphate,which prevents ethylene action,and ethanol,which inhibits ethylene biosynthesis,petal longevity is extended to the detriment of ovary growth. Correlating the physical appearance of the flowers in the presence and absence of ethylene with dry mass and labelled sucrose analyses, carbohydrate movement appeared to be a major event during the senescence of this cut flower. Such a conclusion could not be reached on dry mass analyses alone as the photosynthetic organs of the carnation flower contribute to the carbohydrate pool in the first days following harvest. Furthermore the respiratory pattern of the flower is not a steady decline. Concomitant with the natural ethylene emanation as the petals irreversibly wilt, so the respiratory rate increases. On the other hand, the respiratory rate is greatly reduced with silver thiosulphate and ethanol treatment. In the presence of ethylene, together with the growth of the ovary there is an influx of carbohydrates from all the flower parts including the petals into the ovary. With silver thiosulphate and ethanol treatment the petals become the dominant carbohydrate sink. It thus appears that insufficient carbohydrates moving to the ovary may be the cause of the lack of ovary development. However , an experiment with isolated cultured ovaries on a modified MILLER'S (1965) medium lacking in plant hormones but with a range of sucrose concentrations showed that sucrose alone cannot stimulate ovary growth. The mechanism by which this source-sink relationship is determined appears to be controlled from the sink. The source organs contribute carbohydrates that are in excess of their metabolic needs. Acid invertase activity, maintaining the sucrose gradient into the sink, was considered as a mechanism by which sink strength could be controlled due to the parallel in other plant systems between the activity of this enzyme and sink strength. On investigation the levels of acid invertase activity are higher in the ovaries of senescing carnations than in the petals. This balance of invertase activity was reached mainly due to a decline in petal invertase activity. However, as silver thiosulphate treatment… Advisors/Committee Members: Van Staden, Johannes (advisor).

Subjects/Keywords: Botany.

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Cook, E. L. (2014). The senescence of the cut carnation (Dianthus caryophyllus L. cv. White Sim) flower. (Doctoral Dissertation). University of KwaZulu-Natal. Retrieved from http://hdl.handle.net/10413/10529

Chicago Manual of Style (16^th Edition):

Cook, Elizabeth Louise. “The senescence of the cut carnation (Dianthus caryophyllus L. cv. White Sim) flower.” 2014. Doctoral Dissertation, University of KwaZulu-Natal. Accessed February 25, 2020. http://hdl.handle.net/10413/10529.

MLA Handbook (7^th Edition):

Cook, Elizabeth Louise. “The senescence of the cut carnation (Dianthus caryophyllus L. cv. White Sim) flower.” 2014. Web. 25 Feb 2020.

Vancouver:

Cook EL. The senescence of the cut carnation (Dianthus caryophyllus L. cv. White Sim) flower. [Internet] [Doctoral dissertation]. University of KwaZulu-Natal; 2014. [cited 2020 Feb 25]. Available from: http://hdl.handle.net/10413/10529.

Council of Science Editors:

Cook EL. The senescence of the cut carnation (Dianthus caryophyllus L. cv. White Sim) flower. [Doctoral Dissertation]. University of KwaZulu-Natal; 2014. Available from: http://hdl.handle.net/10413/10529

University of KwaZulu-Natal

16. Jaimangal, Ashika. Some investigations towards the cryopreservation of sugarcane germplasm.

Degree: MS, Botany, 2009, University of KwaZulu-Natal

URL: http://hdl.handle.net/10413/1045

► Sugarcane has become an increasingly important crop in recent years, with South Africa featuring as one of the prominent producers. This has led to a… (more)

▼ Sugarcane has become an increasingly important crop in recent years, with South Africa featuring as one of the prominent producers. This has led to a significant growth in the South African sugarcane industry, translating into an increased demand for planting material. Although this demand is now satisfied by recent biotechnological advancements such as protocols for somatic embryogenesis to increase the production of planting material, such techniques are limited as a result of the progressive loss of the embryogenic potential of calli over time. In order to facilitate management of this material, it is desirable to develop a protocol for the long-term storage of the germplasm. This study reports on investigations of the different parameters that influenced the cryoprocess in attempts to develop a protocol for the successful cryopreservation of sugarcane somatic embryos of the 88H0019 variety. Experiments were carried out to determine in vitro culture conditions for successful induction of somatic embryos via both the direct and indirect routes of micropropagation. A suitable regeneration medium for plantlet establishment pre- and post-cooling was established (Chapter 2). Investigations were also carried out to ascertain the responses of somatic embryos to both rapid and slow dehydration techniques (Chapter 3). Finally, several cooling techniques (both slow and rapid), were applied, on partially dehydrated somatic embryos, either without, or after cryoprotection, in an attempt to achieve survival after cryopreservation of the somatic embryos (Chapter 4). Both directly- and indirectly-derived somatic embryos were converted, most successfully, on full strength Murashige and Skoog medium without addition of plant growth regulators. The initial mean water contents of directly- and indirectly-derived somatic embryos were not significantly different from each other (8.38±0.19 g g-1 and 8.45±0.33 g g-1 [dry mass basis], respectively). The percentage conversion at these water contents was also not significantly different; 97% for directly- and 98% for indirectlyinduced embryos. Slow dehydration by culture on a series of media with increasing concentrations of sucrose (from 0.2 M to 1.2 M) for a period of 48 h each was the most effective technique, with water content being reduced to 0.94±0.03 g g-1 and 0.95±0.02 g g-1 after dehydration on media containing 1.0 M sucrose, while maintaining between 98% and 100% conversion, respectively. Of the various cryoprotectants tested, proline and casamino acid had the least adverse effects on the somatic embryos. The encapsulation-vitrification cooling technique was the most efficient of all techniques employed. The best conditions involved encapsulation of embryo clumps in a solution of MS medium with 3% (w/v) Na-alginate and loading solution containing 2 M glycerol plus 0.4 M sucrose, followed by infiltration and dehydration at 0°C for various time intervals (0, 5, 10, 15, 20, 25, 30 min) with 1 ml PVS2 solution and thereafter, rapid immersion in liquid nitrogen. Under such… Advisors/Committee Members: Pammenter, Norman W (advisor), Berjak, Patricia (advisor).

Subjects/Keywords: Botany.

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APA (6^th Edition):

Jaimangal, A. (2009). Some investigations towards the cryopreservation of sugarcane germplasm. (Masters Thesis). University of KwaZulu-Natal. Retrieved from http://hdl.handle.net/10413/1045

Chicago Manual of Style (16^th Edition):

Jaimangal, Ashika. “Some investigations towards the cryopreservation of sugarcane germplasm.” 2009. Masters Thesis, University of KwaZulu-Natal. Accessed February 25, 2020. http://hdl.handle.net/10413/1045.

MLA Handbook (7^th Edition):

Jaimangal, Ashika. “Some investigations towards the cryopreservation of sugarcane germplasm.” 2009. Web. 25 Feb 2020.

Vancouver:

Jaimangal A. Some investigations towards the cryopreservation of sugarcane germplasm. [Internet] [Masters thesis]. University of KwaZulu-Natal; 2009. [cited 2020 Feb 25]. Available from: http://hdl.handle.net/10413/1045.

Council of Science Editors:

Jaimangal A. Some investigations towards the cryopreservation of sugarcane germplasm. [Masters Thesis]. University of KwaZulu-Natal; 2009. Available from: http://hdl.handle.net/10413/1045

University of KwaZulu-Natal

17. Goveia, Meagan Jayne Theresa. The effect of developmental status and excision injury on the success of cryopreservation of germplasm from non-orthodox seeds.

Degree: MS, Biological and conservation sciences, 2007, University of KwaZulu-Natal

URL: http://hdl.handle.net/10413/1052

► The zygotic germplasm of plant species producing desiccation-sensitive seeds can be conserved in the long-term only by cryopreservation. Usually the embryonic axis is excised from… (more)

▼ The zygotic germplasm of plant species producing desiccation-sensitive seeds can be conserved in the long-term only by cryopreservation. Usually the embryonic axis is excised from the cotyledons and is used as the explant for cryopreservation as it is small and provides a large surface area:volume ratio. However the shoot of the axis of most species studied does not develop after excision, with the result that survival after cryopreservation is often recorded as callus production or simply explant enlargement and/or greening. Thus, besides explant size, factors such as in vitro regeneration techniques, physical injury induced upon excision and developmental status of the seed could compromise the success of cryopreservation. This study investigated the effect of the factors mentioned above, with particular attention to the developmental status of the seeds on explant in vitro development (section 3.1), response to dehydration (section 3.2) and cryopreservation of the desiccation-sensitive embryonic axes (section 3.3) of two species: Trichilia dregeana, T. emetica and embryos of a third, Strychnos gerrardii. For all three species, investigations were conducted on the embryonic axes/embryos excised from mature seeds immediately after fruit harvesting and from mature seeds stored under hydrated conditions for different periods (in order to achieve different degrees of development). In addition, preliminary studies were carried out on axes of T. dregeana to assess whether generation of reactive oxygen species (ROS) occurs in response to wounding upon axis excision (section 3.4). Excised embryonic axes of T. dregeana and T. emetica did not develop shoots in vitro unless the explants included attached cotyledonary segments. Following the development associated with short-term storage, however, the excised axes could develop shoots after complete cotyledon excision. The embryos from the (endospermous) seeds of S. gerrardii which included the paper-thin cotyledons, developed normally in vitro, with percentage germination increasing with seed storage time. For all three species, in vitro axis germination was promoted when activated charcoal was included in the germination medium, regardless of the developmental stage of the seeds. When dehydrated to approximately 0.3 g H2O g-1 dry mass (g g-1), embryonic axes from all three species failed to develop shoots even though a minimum of 50% produced roots in all cases. Hence, shoot production was shown to be more sensitive to desiccation than was root production. Furthermore, the sensitivity of the shoot apical meristem to desiccation was not ameliorated with seed storage for T. dregeana and T. emetica, but did decrease for S. gerrardii when seeds were stored for 6 – 8 weeks. The application of certain cryoprotectants did facilitate production of shoots after dehydration by a few axes of both Trichilia spp. For T. dregeana explants, combination of glycerol and sucrose allowed for 10% of the axes to retain the ability for shoot production after dehydration while for T. emetica… Advisors/Committee Members: Kioko, Joseph Ivala (advisor), Berjak, Patricia (advisor), Pammenter, Norman W (advisor).

Subjects/Keywords: Botany.

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APA (6^th Edition):

Goveia, M. J. T. (2007). The effect of developmental status and excision injury on the success of cryopreservation of germplasm from non-orthodox seeds. (Masters Thesis). University of KwaZulu-Natal. Retrieved from http://hdl.handle.net/10413/1052

Chicago Manual of Style (16^th Edition):

Goveia, Meagan Jayne Theresa. “The effect of developmental status and excision injury on the success of cryopreservation of germplasm from non-orthodox seeds.” 2007. Masters Thesis, University of KwaZulu-Natal. Accessed February 25, 2020. http://hdl.handle.net/10413/1052.

MLA Handbook (7^th Edition):

Goveia, Meagan Jayne Theresa. “The effect of developmental status and excision injury on the success of cryopreservation of germplasm from non-orthodox seeds.” 2007. Web. 25 Feb 2020.

Vancouver:

Goveia MJT. The effect of developmental status and excision injury on the success of cryopreservation of germplasm from non-orthodox seeds. [Internet] [Masters thesis]. University of KwaZulu-Natal; 2007. [cited 2020 Feb 25]. Available from: http://hdl.handle.net/10413/1052.

Council of Science Editors:

Goveia MJT. The effect of developmental status and excision injury on the success of cryopreservation of germplasm from non-orthodox seeds. [Masters Thesis]. University of KwaZulu-Natal; 2007. Available from: http://hdl.handle.net/10413/1052

University of KwaZulu-Natal

18. Masondo, Nqobile Andile. In vitro techniques for the improvement of growth and secondary metabolite production in Eucomis autumnalis subspecies autumnalis.

Degree: Botany, 2014, University of KwaZulu-Natal

URL: http://hdl.handle.net/10413/11440

► The wide utilization and popularity of medicinal plants in African Traditional Medicine (ATM) has been recognized and attributed to the effectiveness, affordability and accessibility of… (more)

▼ The wide utilization and popularity of medicinal plants in African Traditional Medicine (ATM) has been recognized and attributed to the effectiveness, affordability and accessibility of these medicinal plants. However, the extensive exploitation of medicinal plants has exacerbated the strain on the wild populations. In vitro propagation/micropropagation is an effective method which allows for mass production or multiplication of pathogen-free plants that are morphologically and genetically identical to the parent plant. In addition, the technique is contributing to the understanding of metabolic pathways and regulating the production of plant secondary products. Eucomis autumnalis (Mill.) Chitt. subspecies autumnalis (Hyacinthaceae) is a valuable medicinal species in ATM and commonly traded in the urban street markets of South Africa. Currently, the conservation status of this species has not been evaluated. However, as with most bulbous plants, the wild population is continuously under threat due to over-harvesting and habitat loss via various anthropogenic factors. Thus, in vitro propagation is a viable means of ensuring conservation of the plant species. However, mass propagation of medicinal plants should be accompanied with increased secondary metabolite production to guarantee their therapeutic efficacy. Therefore, the current study was aimed at understanding the different factors that affect the growth and secondary metabolite production in micropropagated E. autumnalis subspecies autumnalis. The influence of the type of gelling agent (gelrite versus agar) and source of initial/primary explant source (LDL = leaf explant derived from primary leaf regenerants and LDB = leaf explant derived from primary bulb regenerants) were evaluated. Gelrite-solidified medium significantly improved shoot proliferation when compared to the use of agar as a solidifying medium. In contrast, quantified phytochemicals such as flavonoids and phenolics were more enhanced in agar-supplemented media. On the basis of the explant source, shoot proliferation and secondary metabolites in regenerants from LDB were similar to those from LDL in most cases. Overall, the type of gelling agents and primary explant source individually or/and interactively significantly influenced the growth parameters as well as the production of iridoid, condensed tannin, flavonoid and phenolic content. The influence of different types of plant growth regulators (PGRs) on growth, phytochemical and antioxidant properties were evaluated. The PGRs were BA (benzyladenine); mT (meta-topolin); mTTHP [meta-topolin tetrahydropyran-2-yl or 6-(3-hydroxybenzylamino)-9-tetrahydropyran-2-ylpurine]; MemT [meta-methoxytopolin or 6-(3-methoxybenzylamino)purine]; MemTTHP [meta-methoxy 9-tetrahydropyran-2-yl topolin or 2-[6-(3-Methoxybenzylamino)-9-(tetrahydropyran-2-yl)purine] and NAA (α-naphthalene acetic acid). Five cytokinins (CKs) at 2 μM in combination with varying (0, 2.5, 5, 10, 15 μM) concentrations of NAA were tested. After 10 weeks of in vitro growth, the regenerants… Advisors/Committee Members: Van Staden, Johannes (advisor), Finnie, Jeffrey Franklin (advisor).

Subjects/Keywords: Botany.

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APA (6^th Edition):

Masondo, N. A. (2014). In vitro techniques for the improvement of growth and secondary metabolite production in Eucomis autumnalis subspecies autumnalis. (Thesis). University of KwaZulu-Natal. Retrieved from http://hdl.handle.net/10413/11440

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Masondo, Nqobile Andile. “In vitro techniques for the improvement of growth and secondary metabolite production in Eucomis autumnalis subspecies autumnalis.” 2014. Thesis, University of KwaZulu-Natal. Accessed February 25, 2020. http://hdl.handle.net/10413/11440.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Masondo, Nqobile Andile. “In vitro techniques for the improvement of growth and secondary metabolite production in Eucomis autumnalis subspecies autumnalis.” 2014. Web. 25 Feb 2020.

Vancouver:

Masondo NA. In vitro techniques for the improvement of growth and secondary metabolite production in Eucomis autumnalis subspecies autumnalis. [Internet] [Thesis]. University of KwaZulu-Natal; 2014. [cited 2020 Feb 25]. Available from: http://hdl.handle.net/10413/11440.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Masondo NA. In vitro techniques for the improvement of growth and secondary metabolite production in Eucomis autumnalis subspecies autumnalis. [Thesis]. University of KwaZulu-Natal; 2014. Available from: http://hdl.handle.net/10413/11440

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

University of KwaZulu-Natal

19. Botha, Christiaan Edward Johannes. Studies on the primary phloem of Gomphocarpus physocarpus.

Degree: PhD, Botany, 2014, University of KwaZulu-Natal

URL: http://hdl.handle.net/10413/11455

► Penetration of the stems and leaves of Gomphocnrpus physocarpus by the aphid, Aphis nerii was studied with light and phase microscopes. Penetration of the epidermis… (more)

Subjects/Keywords: Botany.

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APA (6^th Edition):

Botha, C. E. J. (2014). Studies on the primary phloem of Gomphocarpus physocarpus. (Doctoral Dissertation). University of KwaZulu-Natal. Retrieved from http://hdl.handle.net/10413/11455

Chicago Manual of Style (16^th Edition):

Botha, Christiaan Edward Johannes. “Studies on the primary phloem of Gomphocarpus physocarpus.” 2014. Doctoral Dissertation, University of KwaZulu-Natal. Accessed February 25, 2020. http://hdl.handle.net/10413/11455.

MLA Handbook (7^th Edition):

Botha, Christiaan Edward Johannes. “Studies on the primary phloem of Gomphocarpus physocarpus.” 2014. Web. 25 Feb 2020.

Vancouver:

Botha CEJ. Studies on the primary phloem of Gomphocarpus physocarpus. [Internet] [Doctoral dissertation]. University of KwaZulu-Natal; 2014. [cited 2020 Feb 25]. Available from: http://hdl.handle.net/10413/11455.

Council of Science Editors:

Botha CEJ. Studies on the primary phloem of Gomphocarpus physocarpus. [Doctoral Dissertation]. University of KwaZulu-Natal; 2014. Available from: http://hdl.handle.net/10413/11455

University of KwaZulu-Natal

20. Downing, Brian Harvey. A plant ecological survey of the Umfolozi Game Reserve, Zululand.

Degree: PhD, Botany, 2014, University of KwaZulu-Natal

URL: http://hdl.handle.net/10413/11558

► A landscape unit approach based on use of airphotos was used for investigation of Deciduous Acacia Woodland in the Reserve. The approach was useful for… (more)

▼ A landscape unit approach based on use of airphotos was used for investigation of Deciduous Acacia Woodland in the Reserve. The approach was useful for indicating that a quantity of as few as 531 samples could be suitable for sampling woody vegetation over the large, 493 km² area, and for showing where the samples might advantageously be distributed. Use of the approach minimised the extrapolation of community boundaries for mapping purposes. Normal association analysis of the samples revealed the nine woody consociations present and provided quantitative data on species constancy and fidelity. These data were used towards explaining low levels of homogeneity within consociations, as well as some close floristic similarities found between consociations. The successful emergence of a species to dominance in a consociation was ascribed to the presence of a particular, described soil series or rock substrate. The distribution pattern of the consociations resembled a soil-vegetation catena on the landscape. The consociations were grouped into defined physiognomic categories of Open, Closed and Riverine Woodland Associations that were distributed according to three soil associations. The effects of soil factors, fire and the biota on physiognomy, notably secondary thicket encroachment, were discussed; and the relationship between climate and phenology was mentioned. A quantitative description of the grass communities based on normal analysis of stratified sample data revealed a retrogression whereby climax grasses are being replaced by mid-seral and pioneer grasses. The retrogression was ascribed to selective grazing by an increasingly large biomass of enumerated, indigenous herbivores. Some of the management recommendations offered were based on empirically calculated estimates of the weights of dry grass required annually by the grazing animals. Copies of topography, place names, geology, land surface and vegetation maps are provided. The text is supplemented by check lists of plants and animals recorded, by eight figures, 33 tables and 54 photos. Advisors/Committee Members: Bayer, A. W (advisor).

Subjects/Keywords: Botany.

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APA (6^th Edition):

Downing, B. H. (2014). A plant ecological survey of the Umfolozi Game Reserve, Zululand. (Doctoral Dissertation). University of KwaZulu-Natal. Retrieved from http://hdl.handle.net/10413/11558

Chicago Manual of Style (16^th Edition):

Downing, Brian Harvey. “A plant ecological survey of the Umfolozi Game Reserve, Zululand.” 2014. Doctoral Dissertation, University of KwaZulu-Natal. Accessed February 25, 2020. http://hdl.handle.net/10413/11558.

MLA Handbook (7^th Edition):

Downing, Brian Harvey. “A plant ecological survey of the Umfolozi Game Reserve, Zululand.” 2014. Web. 25 Feb 2020.

Vancouver:

Downing BH. A plant ecological survey of the Umfolozi Game Reserve, Zululand. [Internet] [Doctoral dissertation]. University of KwaZulu-Natal; 2014. [cited 2020 Feb 25]. Available from: http://hdl.handle.net/10413/11558.

Council of Science Editors:

Downing BH. A plant ecological survey of the Umfolozi Game Reserve, Zululand. [Doctoral Dissertation]. University of KwaZulu-Natal; 2014. Available from: http://hdl.handle.net/10413/11558

University of KwaZulu-Natal

21. Button, James. Tissue culture studies on citrus and Welwitschia.

Degree: PhD, Botany, 2014, University of KwaZulu-Natal

URL: http://hdl.handle.net/10413/11563

► Part I. IN VITRO CULTURE OF CITRUS EMBRYOS AND NUCELLAR ISOLATES Zygotic embryos of the Ellendale mandarin, a monoembryonic variety of citrus, were cultured on… (more)

▼ Part I. IN VITRO CULTURE OF CITRUS EMBRYOS AND NUCELLAR ISOLATES Zygotic embryos of the Ellendale mandarin, a monoembryonic variety of citrus, were cultured on modified basal media of Murashige and Skoog (BM[1]), and White (BM[2]) , supplemented with various growth regulators and nutrient additives. The growth of immature embryos was greatly enhanced by the addition of 400 mg/l casein hydrolysate (CH) to the basal media. Coconut milk (CM) and malt extract (ME) enhanced growth to a lesser extent, while the addition of indoleacetic acid (IAA) and kinetin (KIN) at the concentrations used, was in no way beneficial. Nucellar isolates excised from abortive and normal Ellendale mandarin ovules eight to 20 weeks after anthesis, were cultured on BM[I] and BM[2] in the presence of various concentrations and combinations of IAA, indolebutyric acid, naph~haleneacetic acid (NAA), 2,4-dichlorophenoxyacetic acid (2,4-D), KIN, CM, benzyl adenine, 6-dimethylallylamino purine, yeast extract (YE), ME, CR, adenine (AD), adenine sulphate (AS), ascorbic acid (AA), and benzylthiazole-2-oxyacetic acid. Some of the isolates which remained alive for four months did develop callus but n~ differentiation of embryoids or other structures occurred. Unfertilized ovules from 8-12-week-old Washington Navel orange fruits provided nucellar isolates which were cultured on media similar to those upon which mandarin nucelli were unsuccessfully cultured. In the case of Navel orange nucelli however, BM[1] + 400 mg/l filter-sterilized ME, and BMl + 40 mg/l AD yielded numerous pseudobulbils which later developed embryoids. Adenine (10 mg/l) was more effective than 20 mg/l which in turn was more effective than 30 mg/l. Adenine was more effective than its equivalent amount supplemented in the sulphate form except at 10 mg/l where the two forms were equally effective. Zeatin (ZE) at 0,2 mg/l did induce some pseudobulbils and embryoids, but all these treatments were less effective than 400 mg/l ME. When transferred to BM[1] + GA[3] (1 mg/l) , embryoids developed roots and later, shoots. It was necessary to remove plantlets from the GA[3]-supplemented medium shortly after the first foliage leaves developed in order to prevent the development of weak, spindly plants . Plantlets were transferred from BM[1 ]+ GA[3] to BM[1] only, and then after careful conditioning they were planted out in soil. This appears to be the first successful attempt at inducing adventive embryogenesis 1n the nucellus of unpollinated, unfertilized citrus ovules in vitro. Part II. EMBRYO AND FREE-CELL CULTURE OF WELWITSCHIA MIRABILIS Welwitschia embryos, cultured on BMI supplemented with CR, and low levels of IAA and KIN, germinated and developed leaves but not roots. Embryos cultured on BM[I] with 5,0 and 10,0 mg/l NAA produced an abundance of friable callus from the hypocotyl root axis. This callus was used for starting suspension cultures aimed at inducing vegetative embryogenesis. A number of nutritional additives and hormones were used alone and in combination at various… Advisors/Committee Members: Bornman, Chris H (advisor).

Subjects/Keywords: Botany.

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APA (6^th Edition):

Button, J. (2014). Tissue culture studies on citrus and Welwitschia. (Doctoral Dissertation). University of KwaZulu-Natal. Retrieved from http://hdl.handle.net/10413/11563

Chicago Manual of Style (16^th Edition):

Button, James. “Tissue culture studies on citrus and Welwitschia.” 2014. Doctoral Dissertation, University of KwaZulu-Natal. Accessed February 25, 2020. http://hdl.handle.net/10413/11563.

MLA Handbook (7^th Edition):

Button, James. “Tissue culture studies on citrus and Welwitschia.” 2014. Web. 25 Feb 2020.

Vancouver:

Button J. Tissue culture studies on citrus and Welwitschia. [Internet] [Doctoral dissertation]. University of KwaZulu-Natal; 2014. [cited 2020 Feb 25]. Available from: http://hdl.handle.net/10413/11563.

Council of Science Editors:

Button J. Tissue culture studies on citrus and Welwitschia. [Doctoral Dissertation]. University of KwaZulu-Natal; 2014. Available from: http://hdl.handle.net/10413/11563

University of KwaZulu-Natal

22. Stuckenberg, Brian Roy. A review of the old world genera of Lauxaniidae (Diptera).

Degree: PhD, Botany, 2014, University of KwaZulu-Natal

URL: http://hdl.handle.net/10413/11549

► This paper presents in key form a review of the Old World genera of Lauxaniidae. Thirteen new genera are erected, three genera are placed in… (more)

Subjects/Keywords: Botany.

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APA (6^th Edition):

Stuckenberg, B. R. (2014). A review of the old world genera of Lauxaniidae (Diptera). (Doctoral Dissertation). University of KwaZulu-Natal. Retrieved from http://hdl.handle.net/10413/11549

Chicago Manual of Style (16^th Edition):

Stuckenberg, Brian Roy. “A review of the old world genera of Lauxaniidae (Diptera).” 2014. Doctoral Dissertation, University of KwaZulu-Natal. Accessed February 25, 2020. http://hdl.handle.net/10413/11549.

MLA Handbook (7^th Edition):

Stuckenberg, Brian Roy. “A review of the old world genera of Lauxaniidae (Diptera).” 2014. Web. 25 Feb 2020.

Vancouver:

Stuckenberg BR. A review of the old world genera of Lauxaniidae (Diptera). [Internet] [Doctoral dissertation]. University of KwaZulu-Natal; 2014. [cited 2020 Feb 25]. Available from: http://hdl.handle.net/10413/11549.

Council of Science Editors:

Stuckenberg BR. A review of the old world genera of Lauxaniidae (Diptera). [Doctoral Dissertation]. University of KwaZulu-Natal; 2014. Available from: http://hdl.handle.net/10413/11549

University of KwaZulu-Natal

23. Van Staden, Johannes. Abscisic acid and other hormonal effects on growth in Spirodela.

Degree: PhD, Botany, 2014, University of KwaZulu-Natal

URL: http://hdl.handle.net/10413/11550

► The effects of abscisic acid In particular, as well well as gibberellic acid and the cytoklnlns, 6-benzyladenine, kinetin, and 6-dlmethylal lalylamlnopurine, on the growth of… (more)

▼ The effects of abscisic acid In particular, as well well as gibberellic acid and the cytoklnlns, 6-benzyladenine, kinetin, and 6-dlmethylal lalylamlnopurine, on the growth of Spirodela oligorrhiza were investigated. Abscisic acid effectively arrested growth permanently at concentrations down to 10¯¹ mg/I. Normal growth tended to be resumed at concentrations of 10¯² and 10¯³ mg/l between nine and twelve days after treatment. A concentration of 10[-8] mg/l, however, resulted in a significant increase in dry weight at both eight, nine and twelve days after introduction into the culture medium. It is suggested that the resumption of growth twelve days after treatment at those concentrations which inhibit growth up to nine days, was due to a possible progressive inactivation of abscisic acid resulting in a lowering of its concentration to a level that is promotive. It was furthermore found that the growth response of Spirodela in terms of dry weight production over a period of eight days is proportional to the log[10] concentration of abscisic acid. It is suggested that this curve can be used as a relatively reliable and easily performed bioassay to detect amounts of abscisic acid as low as 10[-5] μg. The assay is more reliable over the range 0.01 to 10,000 μg and appears not to be affected by gibberellin, benzyladenine and kinetin. The inhibitory effect of abscisic acid on growth in Spirodela was shown to be reversed by benzyladenine, kinetin and dimethylallalylaminopurine, although they were not equally effective in doing so. Benzyladenine at 1.0 mg/l was the most effective In overcoming growth inhibition by abscisic acid. Gibberellic acid, however, proved ineffective in reversing the inhibitory effect of abscisic acid on Spirodela oligorrhiza. The apparent Increases in growth obtained in some cases may have resulted more directly from gibberellic acid stimulation than from the Interaction of gibberel lie acid with abscisic acid. Advisors/Committee Members: Bornman, Chris H (advisor).

Subjects/Keywords: Botany.

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APA (6^th Edition):

Van Staden, J. (2014). Abscisic acid and other hormonal effects on growth in Spirodela. (Doctoral Dissertation). University of KwaZulu-Natal. Retrieved from http://hdl.handle.net/10413/11550

Chicago Manual of Style (16^th Edition):

Van Staden, Johannes. “Abscisic acid and other hormonal effects on growth in Spirodela.” 2014. Doctoral Dissertation, University of KwaZulu-Natal. Accessed February 25, 2020. http://hdl.handle.net/10413/11550.

MLA Handbook (7^th Edition):

Van Staden, Johannes. “Abscisic acid and other hormonal effects on growth in Spirodela.” 2014. Web. 25 Feb 2020.

Vancouver:

Van Staden J. Abscisic acid and other hormonal effects on growth in Spirodela. [Internet] [Doctoral dissertation]. University of KwaZulu-Natal; 2014. [cited 2020 Feb 25]. Available from: http://hdl.handle.net/10413/11550.

Council of Science Editors:

Van Staden J. Abscisic acid and other hormonal effects on growth in Spirodela. [Doctoral Dissertation]. University of KwaZulu-Natal; 2014. Available from: http://hdl.handle.net/10413/11550

University of KwaZulu-Natal

24. Jones, Wayne Russell. Breeding systems of some cold tolerant eucalyptus species.

Degree: MS, Botany, 2014, University of KwaZulu-Natal

URL: http://hdl.handle.net/10413/11561

► Seasonal flowering times for Eucalyptus nitens, E. dunnii, E. smithii, E. macarthurii and E. grandis were evaluated in clonal grafted orchards located at the Shaw… (more)

▼ Seasonal flowering times for Eucalyptus nitens, E. dunnii, E. smithii, E. macarthurii and E. grandis were evaluated in clonal grafted orchards located at the Shaw Research Centre (SRC) in KwaZulu-Natal, South Africa. The orchards are situated at 29° 29 'South, 30° 11 'East at 1100 m above sea level. The climate is cool (MAT 16.7° C) with a January mean monthly maximum of 25.8° C and July minimum of 4.4° C. An estimated mean annual rainfall of 998 mm and median annual rainfall of 899 mm has been reported (PALLETT and MITCHELL 1993). It is evident that the different species flower consistently from one year to the next during the same period with similar mean flowering peaks. Long reproductive sequences where identified for all species relative to E. grandis, particularly E. smithii and E. dunnii. Paclobutrazol was used to initiate flowering to facilitate the study of the breeding systems of the different species. When applied as a soil drench during early summer an increase in the flower bud production in E. nitens, E. smithii and E. grandis was achieved. The use of various cytochemical methods to test pollen viability, were shown to be mere indicators of potential viability and lack the reliability for adequate testing of stored pollen. From the range of in vitro, pollen viability studies the most successful media for all species tested was 30 % sucrose with 150 mg r¯¹ boric acid. Without boric acid in the media, the response after 24 h was significantly poorer (p<0.001). Significant differences (p<0.05) in the area of pollen grains were found between and within species. There was no significant difference between E. dunnii and E. macarthurii at the species level. Pollen of E. smithii, E. grandis and E. nitens were significantly smaller than that of both E. dunnii and E. macarthurii. From isolation experiments which limited potential pollinators it is apparent that a reduction of pollinators not only leads to poorer capsule survival but also poorer seed set. Following an initial survey of pollinators of E. grandis, very few insects were recorded relative to surveys conducted in the natural habitats with indications that an association does exist between the presence of active pollinators and temperature. The potential of flowers to set seed is clearly demonstrated by the difference between open pollinated flowers and controlled pollinated flowers following intraspecific crosses where differences in seed yield per capsule are very often more than double for species such as E. nitens and E. macarthurii. Similarly with interspecific crosses, higher seed yields are extracted from crosses between closely related species. An extensive survey of orchards clearly demonstrates that E. nitens has the lowest clean seed recovery (13.8 %) significantly less than that of E. smithii (18.0 %) and both E. macarthurii and E. dunnii at 26.1 % and 26.0 % respectively. Advisors/Committee Members: Van Staden, Johannes (advisor).

Subjects/Keywords: Botany.

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APA (6^th Edition):

Jones, W. R. (2014). Breeding systems of some cold tolerant eucalyptus species. (Masters Thesis). University of KwaZulu-Natal. Retrieved from http://hdl.handle.net/10413/11561

Chicago Manual of Style (16^th Edition):

Jones, Wayne Russell. “Breeding systems of some cold tolerant eucalyptus species.” 2014. Masters Thesis, University of KwaZulu-Natal. Accessed February 25, 2020. http://hdl.handle.net/10413/11561.

MLA Handbook (7^th Edition):

Jones, Wayne Russell. “Breeding systems of some cold tolerant eucalyptus species.” 2014. Web. 25 Feb 2020.

Vancouver:

Jones WR. Breeding systems of some cold tolerant eucalyptus species. [Internet] [Masters thesis]. University of KwaZulu-Natal; 2014. [cited 2020 Feb 25]. Available from: http://hdl.handle.net/10413/11561.

Council of Science Editors:

Jones WR. Breeding systems of some cold tolerant eucalyptus species. [Masters Thesis]. University of KwaZulu-Natal; 2014. Available from: http://hdl.handle.net/10413/11561

University of KwaZulu-Natal

25. Howden, Jean Blair. Isolation and characterisation of senescence-related genes in carnations.

Degree: MS, Botany, 2014, University of KwaZulu-Natal

URL: http://hdl.handle.net/10413/11552

► Senescence has been the subject of many studies, with the ultimate goal of increasing longevity of cut flowers, and for insight into the process of… (more)

▼ Senescence has been the subject of many studies, with the ultimate goal of increasing longevity of cut flowers, and for insight into the process of ageing. Senescence in the carnation is a complex phenomonen involving many physiological and molecular events. The carnation serves as an excellent subject for studies in senescence because of the clearly visible evidence of "in-rolling" of petals indicating the onset of senescence. Senescence in the carnation results in a large number of physiological changes in the flower which in many cases involve the action of the growth regulating hormones, particularly ethylene. Physiological studies of senescence, though exhaustive, have not as yet been able to pinpoint the source of control of senescence in the carnation and the exact controlling mechanism. Senescence has in the past been shown to be partially regulated at the transcriptional level, thus warranting studies in the area of molecular biology. The aim of the present investigation was to isolate genes active during senescence . To achieve this, mRNA from presenescent and senescing carnation petals, receptacles and ovaries was extracted. The mRNA was used to synthesise cDNA which was cloned into ۸gt10 phage to produce presenescent and senescing cDNA libraries of carnation material. The production of the petal library was the only library that, after boosting levels of petal cDNA using PCR (polymerase chain reaction) technology; was generated successfully. A subtraction procedure was carried out between the presenescent and senescing libraries to isolate the sequences unique to the senescing library ie. the genes active only during senescence. One sequence of 1 kb in size was isolated. This gene could be used for future research into the influence of the growth regulators on its activity, and also to pinpoint organs other than the petals where this particular gene is active. It would be of interest to investigate the sequence of the gene, for a comparison with other gene isolates in order to elucidate the identity and function of the gene product. Advisors/Committee Members: Van Staden, Johannes (advisor), Cress, William A (advisor).

Subjects/Keywords: Botany.

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APA (6^th Edition):

Howden, J. B. (2014). Isolation and characterisation of senescence-related genes in carnations. (Masters Thesis). University of KwaZulu-Natal. Retrieved from http://hdl.handle.net/10413/11552

Chicago Manual of Style (16^th Edition):

Howden, Jean Blair. “Isolation and characterisation of senescence-related genes in carnations.” 2014. Masters Thesis, University of KwaZulu-Natal. Accessed February 25, 2020. http://hdl.handle.net/10413/11552.

MLA Handbook (7^th Edition):

Howden, Jean Blair. “Isolation and characterisation of senescence-related genes in carnations.” 2014. Web. 25 Feb 2020.

Vancouver:

Howden JB. Isolation and characterisation of senescence-related genes in carnations. [Internet] [Masters thesis]. University of KwaZulu-Natal; 2014. [cited 2020 Feb 25]. Available from: http://hdl.handle.net/10413/11552.

Council of Science Editors:

Howden JB. Isolation and characterisation of senescence-related genes in carnations. [Masters Thesis]. University of KwaZulu-Natal; 2014. Available from: http://hdl.handle.net/10413/11552

University of KwaZulu-Natal

26. Butler, Valerie. Ultrastructure of the germinating Welwitschia mirabilis seed.

Degree: PhD, Botany, 2014, University of KwaZulu-Natal

URL: http://hdl.handle.net/10413/11565

► The structure and chemical composition of quiescent Welwitschia mirabilis (Hooker fil.) seeds and resultant changes occurring during the first 7 days of germination were studied.… (more)

▼ The structure and chemical composition of quiescent Welwitschia mirabilis (Hooker fil.) seeds and resultant changes occurring during the first 7 days of germination were studied. Research was focussed on the megagametophyte and its interrelationship with the non-vascularised outgrowth produced by the embryo. This outgrowth was given the name "feeder" by Bower in 1881 who postulated that it functions as an absorptive organ. However the possibility existed that it merely fulfilled the mechanical role of anchorage. Following hydration activation of embryonic collar cells precedes that of gametophyte cells whose rate of activation is governed by relative distance from the embryo. This sequence of activation is suggestive of a stimulatory factor diffusing from the embryo into the gametophyte. Starch, protein and lipid reserves in the collar and developing feeder are consumed within 36 to 48 h. As a consequence the rapidly developing seedling is probably largely dependent on nutrient material in the gametophyte until the plumule emerges, after approximately 5 to 6 days germination. Ventral feeder cells in contact with gametophyte tissue apparently act as transfer cells, developing numerous small wall projections invested with plasmalemma which result in a much greater absorptive surface area. The large numbers of mitochondria occurring in these cells might suggest active uptake of nutrients. At the 3- to 4-day-stage the feeder and gametophyte adhere firmly. While this adherance probably facilitates translocation of nutrients it could also have the secondary function of anchoring the feeder in the gametophyte, thus providing the emerging plumule with a firm base. The apparent root cap origin of ventral feeder cells might explain the positive geotropism of the feeder, as recent work inter alia by Wilkins and Wain (1975) has shown that root cap cells may be geoperceptive. Cytochemical methods used at the light and electron microscope level suggest that reserve material within protein bodies of the embryo and gametophyte might exist as a proteincarbohydrate complex and that globoid origin might be cytoplasmic. The immediate digestion of protein body reserves in the embryo and gametophyte interface zone argues the presence of pre-existing hydrolytic enzymes laid down within the protein bodies prior to quiescence. However the enzymes responsible for reserve breakdown in deep gametophyte tissue seem to be synthesised de nova. Protein hydrolysis precedes lipid digestion which possibly indicates that some of the resulting free amino acids might be used in the de nova synthesis of lipases. Lipid bodies, microbodies, mitochondria and amyloplasts encircled with ER seem to form a complex. Fatty acids resulting from lipase action in the lipid bodies (Ching 1968) are probably converted by microbodies (glyoxysomes) to succunate (Breidenbach and Beevers 1967) which is converted to sucrose by the action of mitochondria (Cooper and Beevers 1969a, b). Excess sucrose is probably converted to starch and stored in the amyloplasts. In 5 days the… Advisors/Committee Members: Bornman, Chris H (advisor).

Subjects/Keywords: Botany.

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APA (6^th Edition):

Butler, V. (2014). Ultrastructure of the germinating Welwitschia mirabilis seed. (Doctoral Dissertation). University of KwaZulu-Natal. Retrieved from http://hdl.handle.net/10413/11565

Chicago Manual of Style (16^th Edition):

Butler, Valerie. “Ultrastructure of the germinating Welwitschia mirabilis seed.” 2014. Doctoral Dissertation, University of KwaZulu-Natal. Accessed February 25, 2020. http://hdl.handle.net/10413/11565.

MLA Handbook (7^th Edition):

Butler, Valerie. “Ultrastructure of the germinating Welwitschia mirabilis seed.” 2014. Web. 25 Feb 2020.

Vancouver:

Butler V. Ultrastructure of the germinating Welwitschia mirabilis seed. [Internet] [Doctoral dissertation]. University of KwaZulu-Natal; 2014. [cited 2020 Feb 25]. Available from: http://hdl.handle.net/10413/11565.

Council of Science Editors:

Butler V. Ultrastructure of the germinating Welwitschia mirabilis seed. [Doctoral Dissertation]. University of KwaZulu-Natal; 2014. Available from: http://hdl.handle.net/10413/11565

University of KwaZulu-Natal

27. Okubamichael, Desale Yosief. Host specificity of the hemiparasitic mistletoe, Agelanthus natalitius.

Degree: MS, Botany, 2009, University of KwaZulu-Natal

URL: http://hdl.handle.net/10413/10821

► Mistletoes are a group of hemiparasitic plants that grow on a wide variety of host trees and differ in their degree of host specificity, ranging… (more)

▼ Mistletoes are a group of hemiparasitic plants that grow on a wide variety of host trees and differ in their degree of host specificity, ranging from specialists to generalists. Mistletoes can also be locally host specific where host preference varies geographically, i.e. at a given location a mistletoe species may infect only part of its overall host set. The mistletoe Agelanthus natalitius parasitises at least 11 tree genera distributed throughout South Africa. However, there is geographic variation in infection patterns over the parasite’s range, suggesting that A. natalitius may be locally host specific. We quantified the degree of host specificity and tested the mechanisms that direct host specialisation in two distinct mistletoe populations at Highover and Mtontwane (about 110 km apart) in KwaZulu-Natal, South Africa. We investigated the distribution, abundance and community composition of woody species that host the mistletoe. We also assessed the effect of light on germination and early survival of the mistletoes in a greenhouse experiment. We conducted field reciprocal transplant experiments at both sites to investigate the compatibility of these mistletoes with their hosts Acacia karroo and A. caffra during early development. We then analysed the nutrient and water contents of the mistletoe-host pairs to investigate the role of nutrient and water status in directing host specificity in mistletoes. We further studied avian dispersal in the field and in captivity to investigate optimal dispersal distance and germination success, and evaluated their role in determining mistletoe host specificity. At both study sites, five host species were recorded as being parasitised by the mistletoe A. natalitius. A. karroo and A. caffra appear to be the two most common host species in the region; both grow abundantly at the study sites and were recorded with high infection by A. natalitius. However, A. karroo is the most abundant host species and the mistletoe showed a high degree of host specificity on A. karroo. Infection by mistletoes was positively correlated with tree size, and was highly aggregated, both individually and locally. Field observations and greenhouse shade experiments showed that light can influence mistletoe distribution. Germination of mistletoe seeds was independent of host species and site. However, hypocotyls (the structures that develop into haustoria) grew longer when placed on their source host species within their locality. Additionally, they showed preference for the most abundant host species, A. karroo. Water and nutrient status of the host species A. karroo and A. caffra had no significant effect. Thus, host nutrient and water content may not account for host specificity in this mistletoe species. Mistletoes accumulated more nutrients and maintained more negative than their host trees. We also investigated the mistletoes’ use of passive nutrient uptake (from host xylem) and active nutrient uptake (from host phloem) by using the N:Ca ratio as an index of nutrient access. Mistletoes growing on… Advisors/Committee Members: Ward, David Mercer (advisor), Griffiths, M. E (advisor).

Subjects/Keywords: Botany.

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Okubamichael, D. Y. (2009). Host specificity of the hemiparasitic mistletoe, Agelanthus natalitius. (Masters Thesis). University of KwaZulu-Natal. Retrieved from http://hdl.handle.net/10413/10821

Chicago Manual of Style (16^th Edition):

Okubamichael, Desale Yosief. “Host specificity of the hemiparasitic mistletoe, Agelanthus natalitius.” 2009. Masters Thesis, University of KwaZulu-Natal. Accessed February 25, 2020. http://hdl.handle.net/10413/10821.

MLA Handbook (7^th Edition):

Okubamichael, Desale Yosief. “Host specificity of the hemiparasitic mistletoe, Agelanthus natalitius.” 2009. Web. 25 Feb 2020.

Vancouver:

Okubamichael DY. Host specificity of the hemiparasitic mistletoe, Agelanthus natalitius. [Internet] [Masters thesis]. University of KwaZulu-Natal; 2009. [cited 2020 Feb 25]. Available from: http://hdl.handle.net/10413/10821.

Council of Science Editors:

Okubamichael DY. Host specificity of the hemiparasitic mistletoe, Agelanthus natalitius. [Masters Thesis]. University of KwaZulu-Natal; 2009. Available from: http://hdl.handle.net/10413/10821

University of KwaZulu-Natal

28. Russell, Jennifer Mary. Vegetation change in Northern KwaZulu-Natal since the Anglo-Zulu war of 1879.

Degree: 2015, University of KwaZulu-Natal

URL: http://hdl.handle.net/10413/11968

► Historic photographs have been successfully used to compare landscape change over time. I used photographs taken of the grassland biome during and just after the… (more)

▼ Historic photographs have been successfully used to compare landscape change over time. I used photographs taken of the grassland biome during and just after the Anglo-Zulu War (1879) in KwaZulu-Natal (South Africa), which are some of the earliest known available landscape photographs. The study area encompassed Fugitives’ Drift, Isandlwana and Rorke’s Drift and included communal and commercial rangelands, as well as conservation areas. These fixed-point photographs showed a dramatic increase in woody cover (< 82.5%) since the Anglo-Zulu War in all three land-use types. Floristic sampling showed that while vegetation structure did not differ significantly, plant species diversity and richness differed significantly for each land-use type. I also used a set of aerial photographs to give a much wider perspective of the landscape changes for the study area from 1944 to 2005. These images indicated that the increase in woody cover was progressive, with most of the woody plant recruitment occurring prior to 1964. Thereafter, the increase in woody plant cover was due to bush-clump thickening rather than recruitment into grasslands. This pattern did not occur, however, in the commercial rangeland, where recruitment into open grassland commenced in the 1980s. Although the theory of patch dynamics is cyclical in nature, this model may fit the patterns observed in the study area. Analysis of rainfall and temperature data showed that there has been a decrease in average annual rainfall since 1902 and an increase in minimum daily temperature since 1973. However, the decrease in mean annual rainfall is not consistent with woody plant encroachment. While the increase in mean annual daily temperature appears consistent with a shift to an environment typical of savannas, woody plant encroachment started before the increase in daily temperature. A survey of long-term residents in the study area with regard to livestock numbers, grazing patterns, fire and wood harvesting was also inconclusive. I, therefore, speculate that increasing levels of atmospheric CO2 is driving bush encroachment, with the other drivers such as rainfall, temperature, absence of intense fires, grazing patterns and land-use, playing a modifying role. Advisors/Committee Members: Ward, David Mercer (advisor).

Subjects/Keywords: Botany.

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APA (6^th Edition):

Russell, J. M. (2015). Vegetation change in Northern KwaZulu-Natal since the Anglo-Zulu war of 1879. (Thesis). University of KwaZulu-Natal. Retrieved from http://hdl.handle.net/10413/11968

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Russell, Jennifer Mary. “Vegetation change in Northern KwaZulu-Natal since the Anglo-Zulu war of 1879.” 2015. Thesis, University of KwaZulu-Natal. Accessed February 25, 2020. http://hdl.handle.net/10413/11968.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Russell, Jennifer Mary. “Vegetation change in Northern KwaZulu-Natal since the Anglo-Zulu war of 1879.” 2015. Web. 25 Feb 2020.

Vancouver:

Russell JM. Vegetation change in Northern KwaZulu-Natal since the Anglo-Zulu war of 1879. [Internet] [Thesis]. University of KwaZulu-Natal; 2015. [cited 2020 Feb 25]. Available from: http://hdl.handle.net/10413/11968.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Russell JM. Vegetation change in Northern KwaZulu-Natal since the Anglo-Zulu war of 1879. [Thesis]. University of KwaZulu-Natal; 2015. Available from: http://hdl.handle.net/10413/11968

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

University of KwaZulu-Natal

29. Boyes, Lauren J. Regeneration failure and the Acacia karroo successional pathway in coastal dune forests in KwaZulu-Natal, South Africa.

Degree: MS, Botany, 2007, University of KwaZulu-Natal

URL: http://hdl.handle.net/10413/4707

► Monospecific stands of Acacia karroo establish naturally on disturbed coastal dunes in KwaZulu-Natal, South Africa. While the A. karroo successional pathway is successful in rehabilitating… (more)

▼ Monospecific stands of Acacia karroo establish naturally on disturbed coastal dunes in KwaZulu-Natal, South Africa. While the A. karroo successional pathway is successful in rehabilitating mined dunes at the Richards Bay Minerals mining company (RBM), the same pathway has become arrested in the coastal dune forest at Cape Vidal in the Greater St. Lucia Wetland Park. This study examines the efficacy of the A. karroo successional pathway for restoring disturbed coastal dune forests. Dispersal of seeds and successful recruitment of seedlings are essential for habitat restoration. Seed and seedling banks were compared between previously disturbed A. karroo stands and adjacent forest at Cape Vidal. Different seed bank composition and higher seed bank richness in the forest suggest that seed dispersal into A. karroo stands is limited. Protected seed banks in A. karroo stands had increased seedling richness, indicating that dispersal limitation does not fully explain the lack of seedling establishment. At RBM, the seed bank richness of A. karroo stands increased with age since mining. While cumulative species richness of the seed bank of the oldest A. karroo stand at RBM was marginally lower than that at Cape Vidal, successful rehabilitation at RBM is associated with low seedling mortality. Consequently, forest tree species richness is high at RBM in the A. karroo stands and is converging on natural forest richness and composition. Although seed dispersal is reduced, it does not totally limit establishment of forest tree species in A. karroo stands at Cape Vidal, which implicates a post-establishment factor. Soil fertility potentially reduces seed germination and seedling growth. Soil nutrients in A. karroo stands at Cape Vidal were similar to those in the adjacent forest, and total nitrogen levels in A. karroo stands at Cape Vidal were higher than at RBM. Thus, soil conditions were unlikely to be limiting tree regeneration in A. karroo stands. Total nitrogen accumulated in the oldest stand at RBM at a rate of 10.0 g.m2.y(1 and a similarly rapid rate occurred at Cape Vidal. Therefore the A. karroo stands were not nitrogen limited. Nitrogen supplementation experiments at Cape Vidal demonstrated that a range of forest tree species establish in A. karroo stands regardless of nitrogen level, but there is low survival of seedlings. Thus, nitrogen availability is not arresting succession at Cape Vidal. Herbivory can also inhibit seedling recruitment. Selective feeding may enhance the persistence of species with defences against herbivory, such as A. karroo, ultimately altering the tree community composition. Browsing and trampling by large mammalian herbivores in A. karroo stands at Cape Vidal decreased survival and growth of forest tree seedlings. Large herbivores such as kudu, waterbuck, bushbuck and red duiker preferentially used the A. karroo stands as they offer abundant food and their topography allowed easy movement. This topdown pressure reduced recruitment, growth, and survival of seedlings of undefended species. Few… Advisors/Committee Members: Lawes, Michael J (advisor), Griffiths, M. E (advisor).

Subjects/Keywords: Botany.

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APA (6^th Edition):

Boyes, L. J. (2007). Regeneration failure and the Acacia karroo successional pathway in coastal dune forests in KwaZulu-Natal, South Africa. (Masters Thesis). University of KwaZulu-Natal. Retrieved from http://hdl.handle.net/10413/4707

Chicago Manual of Style (16^th Edition):

Boyes, Lauren J. “Regeneration failure and the Acacia karroo successional pathway in coastal dune forests in KwaZulu-Natal, South Africa.” 2007. Masters Thesis, University of KwaZulu-Natal. Accessed February 25, 2020. http://hdl.handle.net/10413/4707.

MLA Handbook (7^th Edition):

Boyes, Lauren J. “Regeneration failure and the Acacia karroo successional pathway in coastal dune forests in KwaZulu-Natal, South Africa.” 2007. Web. 25 Feb 2020.

Vancouver:

Boyes LJ. Regeneration failure and the Acacia karroo successional pathway in coastal dune forests in KwaZulu-Natal, South Africa. [Internet] [Masters thesis]. University of KwaZulu-Natal; 2007. [cited 2020 Feb 25]. Available from: http://hdl.handle.net/10413/4707.

Council of Science Editors:

Boyes LJ. Regeneration failure and the Acacia karroo successional pathway in coastal dune forests in KwaZulu-Natal, South Africa. [Masters Thesis]. University of KwaZulu-Natal; 2007. Available from: http://hdl.handle.net/10413/4707

University of KwaZulu-Natal

30. Mtshali, Ntombizamatshali Prudence. Role of light and temperature in the flowering of Watsonia species.

Degree: MS, Botany, 2006, University of KwaZulu-Natal

URL: http://hdl.handle.net/10413/5503

► The role of light and temperature on flowering of South African Watsonia species were evaluated to assess the potential for this genus as a commercial… (more)

▼ The role of light and temperature on flowering of South African Watsonia species were evaluated to assess the potential for this genus as a commercial flower crop. Species were selected that represent different climatic regions of South Africa, with the aim of understanding how ecologically distinct species perform under cultivation. The four selected species were W. borbonica and W. tabularis (winter-rainfall area), W. angusta (shared rainfall) and W. pillansii (summer-rainfall area). In order to establish the optimum temperature required for flowering, plants were exposed for 12 weeks to three temperature regimes (12/7 °C, 21/15 °C and 29/21 °C) after attaining their first and/or second leaves. A temperature shift of 12/7 °C was used to assess if the plants had a vemalisation requirement. Controls were maintained under 25 % shade under natural conditions, with an average temperature of 24/7 °C. An elevated temperature of 29/21 °C was detrimental to plant growth. Moderate temperatures of 21/15 °C significantly (P<0.001) increased the height and the number of leaves produced per plant relative to the 12/7 °C treatment. These temperatures significantly (P<0.001) increased the total number of flowers produced per plant compared to low temperatures. However, flowering percentage and quality of flowers were reduced. A low temperature regime of 12/7 °C was efficient in satisfying vernalisation requirements and inducing flowering in four selected species. However, the total number of leaves produced per plant was signifcantly reduced. The summer-rainfall species, W pillansii, displayed a qualitative response to vernalisation, as no flowering was observed in non-vernalised plants. Two winter-rainfall species, W borbonica and W. tabularis, demonstrated a quantitative response to vernalisation. These species flowered at non-vernalising temperatures. W angusta behaved like the winter-rainfall species in terms of flowering. Overall, a vernalisaton treatment marginally reduced days to flower while flowering percentage was increased compared to other temperature regimes. However, there was no increase in the total number of flowers produced per plant. Low temperatures were not only effective for flower induction, but also for releasing corm dormancy, thus synchronising growth. Storing corms at either 4 or 10 QC resulted in 100 % sprouting within 4-6 weeks. The role of daylength in flowering of Watsonia plants was established by subjecting plants to long days (LO) of 16 h light and 8 h dark and to short days (SO) of 8 h light and 16 h dark. The number of leaves and flowering were significantly (P<0.01) promoted under the LO regime. However, there was strong temperature and daylength interaction in terms of flowering potential, as at low temperatures flowering was induced irrespective of daylength. In W. pillansii, flowering was obtained under both regimes (LO and SO) applied at the second leaf stage. Flowering in W. borbonica and W. tabularis was only observed under the LO regime at the second leaf stage. In both species,… Advisors/Committee Members: Van Staden, Johannes (advisor), Thompson, David Ian (advisor), Erwin, J (advisor).

Subjects/Keywords: Botany.

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APA (6^th Edition):

Mtshali, N. P. (2006). Role of light and temperature in the flowering of Watsonia species. (Masters Thesis). University of KwaZulu-Natal. Retrieved from http://hdl.handle.net/10413/5503

Chicago Manual of Style (16^th Edition):

Mtshali, Ntombizamatshali Prudence. “Role of light and temperature in the flowering of Watsonia species.” 2006. Masters Thesis, University of KwaZulu-Natal. Accessed February 25, 2020. http://hdl.handle.net/10413/5503.

MLA Handbook (7^th Edition):

Mtshali, Ntombizamatshali Prudence. “Role of light and temperature in the flowering of Watsonia species.” 2006. Web. 25 Feb 2020.

Vancouver:

Mtshali NP. Role of light and temperature in the flowering of Watsonia species. [Internet] [Masters thesis]. University of KwaZulu-Natal; 2006. [cited 2020 Feb 25]. Available from: http://hdl.handle.net/10413/5503.

Council of Science Editors:

Mtshali NP. Role of light and temperature in the flowering of Watsonia species. [Masters Thesis]. University of KwaZulu-Natal; 2006. Available from: http://hdl.handle.net/10413/5503

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