Thesis (M.Sc.(Systematics and Biodiversity Science))-- Stellenbosch University, 2001. / ENGLISH ABSTRACT: Sequence data from the intron and the spacer of the trnL-F chloroplast DNA region were used to study the phylogenetic relationships of the genus Zygophyllum L. (Zygophylloideae: Zygophyllaceae) in the southern African region. The chloroplast DNA was extracted from both herbarium and silica-gel dried material. Closely related genera, i.e. Augea Thunb., Fagonia L. and Tetraena Maxim. within the subfamily Zygophylloideae and more distantly related genera Seetzenia R.Br. ex Decne and Tribulus L. were used as outgroups. Sequences revealed length variation mainly due to the presence of indels (insertions and deletions). Phylogenetic analysis using parsimony revealed two distinct lineages for southern African members of Zygophyllum, corresponding to the proposed subgeneric classification (Van Huysteen 1937; Van Zyl 2000). There is a strong monophyly support for the sections within the subgenus Agrophyllum (Neck.) Endl. However, the transference of the monotypic section Grandifolia Engl. from subgenus Zygophyllum to Agrophyllum is not confirmed, because material of Z. stapffii Schinz. was not available. Despite the morphological evidence for the subdivision of the subgenus Zygophyllum, the molecular data did not confirm the monophyly for its sections. This could be the result of biased sampling, since all the species used in the analyses, except Z. cordifolium L.f. and Z. morgsana L., belong to section Capensia Engl. The trnL region data support the transfer of the mono typic section Morgsana Huysst. from subgenus Agrophyllum to subgenus Zygophyllum. The molecular data also seem to have implications for the biogeography of Zygophyllum. The southern African Agrophyllum representatives are related to East African and Middle East Zygophyllum species, whereas the southern African subgenus Zygophyllum members are closely related to Australian Zygophyllum species. / AFRIKAANSE OPSOMMING: Die volgorde-data van die trnL-F chloroplas-DNA gebied is gebruik om die filogenetiese verwantskappe van die genus Zygophyllum L. (Zygophylloideae: Zygophyllaceae) in suider Afrika te bestudeer. Die chloroplas-DNA is geëkstraheer van beide herbaria en silica-gel gedroogde materiaal. Naverwante genera binne die subfamilie Zygophylloideae bv. Augea Thunb., Fagonia L. en Tetraena Maxim., sowel as verder verwante genera, soos Seetzenia R.Br. ex Decne en Tribulus L., was as buite-groepe gebruik. Die lengte-variasie in die volgorde-data kan toegeskryf word aan indels (insertions and deletions). Filogenetiese analise deur die gebruik van parsimonie het twee duidelike ontwikkelingslyne vir suider-Afrikaanse Zygophyllum taksa aangedui. Dit stem goed ooreen met die voorgestelde subgeneriese klassifikasiesisteem vir die genus (Van Huysteen1937; Van Zyl 2000). Daar is 'n sterk ondersteuning vir monofilie van die seksies binne die subgenus Agrophyllum (Neck.) Endl. Die oorplasing van die monotipiese seksie Grandifolia Engl. vanaf subgenus Zygophyllum na subgenus Agrophyllum is nie bevestig nie, want materiaal van Z. stapffii Schinz. was nie beskikbaar nie. Ten spyte van morfologiese bewyse vir die subdivisie van die subgenus Zygophyllum het die molekulêre data nie die monofilie van die seksies bevestig nie. Dit is moontlik as gevolg van eensydige data-insameling, aangesien al die spesies wat in die analise gebruik word (behalwe Z. cordifolium L.f. en Z. morgsana L.) aan die seksie Capensia Engl. behoort. Die trnL-gebied data ondersteun die oordra van die monotipiese seksie Morgsana Huysst. van die subgenus Agrophyllum na die subgenus Zygophyllum. Die molekulêre data bied ode inligting oor die biogeografie van Zygophyllum. Die suider-Afrikaanse Agrophyllum taksa is verwant aan Oos-Afrika en Midde-Oosterse Zygophyllum spesies, terwyl lede van die Suid-Afrikaanse subgenus Zygophyllum nouverwant is aan Zygophyllum spesies in Australië.

Thesis (MSc (Botany and Zoology))--University of Stellenbosch, 2005. / The main substrate use during shoot establishment from the lateral bud of sugarcane setts and enzymes involved in sucrose metabolism were investigated in the shoots and the internodes acting as source of carbohydrates. Radiolabelling studies were conducted to investigate the metabolism of sucrose and glucose during shoot establishment. The internode’s total dry mass over the 21-day of shoot establishment period was reduced by 25% and 30% in plants incubated in dark/light and total darkness, respectively.

Thesis (MSc)--Stellenbosch University, 2002. / ENGLISH ABSTRACT:Several authors regard the subdivision of the large genus Heliophila as unsatisfactory and in need of a detailed taxonomic study. Previous studies on this genus were based exclusively on gross external morphological characters. The present study investigates patterns of variation in Heliophila in order to identify taxonomically informative characters that could be used in the subdivision of this large genus. The study differs from previous studies in Heliophila because, in addition to macro-morphology, it employs micro- morphological (SEM) and palynological evidence to elucidate the subdivisio.n of Heliophila. The study emanates from a taxonomic revision of Heliophila proposed by Sander (1860), in which he subdivided the genus into six sections, based on the variation in fruit characters. Subsequent authors ignored the sections, regarding the generic subdivision as insufficiently supported, hence unsatisfactory . The results of cluster analysis, which are based on all the characters examined in the study (overall variation), propose the subdivision of Heliophila into three main clades: Micromorphological characters of fruits, seeds, and leaves are consistently found to be more congruent with the phenogram than macro-morphological characters of the same organs. This suggests that micro-morphological characters are taxonomically informative in Heliophila and should prove very important in a future phylogenetic classification of the genus. Palynological characters were found to be of limited taxonomic importance in the subdivision of the genus. / AFRIKAANSE OPSOMMING: Verskeie outeurs beskou die onderverdeling van die groot genus Heliophila as onbevredigend, en meen dat dit 'n gedetaileerde taksonomies studie benodig. Vorige studies op hierdie genus het slegs op ekstern morfologiese kenmerke gekonsentreer. In die huidige studie word patrone van variasie in Heliophila ondersoek met die oog op 'n moontlike onderverdeling van die genus, en taksonomies betek~nisvolle kenmerke wat in hierdie verband gebruik kan word, word geidentifiseer. Die huidige stud'e verskil van vorige studies daarin dat, benewens makro-morfologiese kenmerke, dit ook mikro-~rfologiese tegnieke (SEM) en palinologiese kenmerke gebruik om 'n sinvolle subverdeling van Heliophila te probeer vind. Die huidige studie spruit uit 'n taksonomiese hersiening van Heliophila deur Sonder (1860), waarin hy voorstel dat die genus in ses seksies verdeel word op grond van variasie in vrug kenmerke. Hierdie generiese onderverdeling en die voorgestelde seksies is deur latere outeurs as onbevredigend beskou, en is meestal in die literatuur geignoreer. Die resultate van fenetiese analise, wat op alle ingeslote kenmerke gebaseer is (algehele variasie), stel voor dat Heliophila in drie hoof groepe verdeel moet word. Taksonomies belangrike kenmerke wat hierdie onderverdeling ondersteun sluit in blaartipe, variasie in blaar-oppervlakke (SEM), variasie in die aard van die saadhuid (SEM) en variasie in vrugoppervlakke (SEM). Palinologiese en makro-morfologiese kenmerke was van geringe waarde in die onderverdeling van die genus.

Thesis (MSc)--Stellenbosch University, 2003. / ENGLISH ABSTRACT: Oxalis L. has two centres of diversity, one in South-Central America and the other in southern Africa. Previous palynological studies of southern Africa Oxalis revealed four main pollen types, namely rugulate-reticulate, micro-rugulate-spinate, reticulate and supra-areolate (Dreyer 1996). The reticulate pollen type is further divided into 15 subtypes, out of which five have a monotypic status. The supra-areolate pollen type is divided into four subtypes based on exine structure. The reticulate pollen type is the most common pollen type within the South African members of Oxalis. The three remaining main pollen types display more complex exine structures and are therefore considered more derived than the reticulate pollen type. The present study assessed the pollen of 50 American Oxalis species with three main objectives: 1. To observe pollen type variations among American members of Oxalis, 2. To compare pollen types from the two centres of diversity, and 3. To assess which centre of diversity house the palynologically more advanced species of Oxalis. Two main pollen types are recorded from the present study, namely reticulate and verrucate pollen types. The reticulate pollen type could be further divided into 11 subtypes. Out of the 11 subtypes observed, nine also occur among South African members of Oxalis, while two types are only observed in the American members of Oxalis. The verrucate pollen type is found in a single American taxon and displays a more complex exine structure than the reticulate pollen type. In this study the reticulate pollen type proved to be the most common pollen type among the American members of Oxalis. The South African members of Oxalis display more complex pollen types than the American members of the genus. / AFRIKAANSE OPSOMMING: Oxalis L. het twee diversiteitsentrums, een in Suid-Sentraal Amerika en die ander in suidelike Afrika. Palinologiese studies van suidelike Afrika Oxalis-taksa toon vier hoofstuifmeeltipes, naamlik gerimpel-netvormig, fyn-gerimpel-stekelrig, netvormig en supra-areolêr (Dreyer 1996). Die netvormige stuifmeeltipe word verder verdeel in 15 subtipes. Vyfvan hierdie tipes het 'n monotipiese status. Die supra-areolêre stuifmeeltipe word verdeel in vier subtipes gebaseer op eksienstruktuur. Die netvormige stuifmeeltipe is die mees algemene stuifmeeltipe aanwesig in die Suid Afrikaanse Oxalis-taksa. Die drie oorblywende hoofstuifmeeltipes toon 'n meer komplekse eksienstruktuur en word as meer gevorderd as die netvormig stuilmeeltipe beskou. In die huidige studie is stuifmeelkorrels van 50 Amerikaanse Oxalis spesies bestudeer met drie doelstellings in gedagte: 1. Om die variasie in die stuifmeeltipes van die Amerikaanse spesies van Oxalis te bestudeer, 2. Om die stuifmeeltipes van die twee diversiteitsentrurns te vergelyk, en 3. Om vas te stel watter diversiteitsentrum het palinologies die meer gevorderde spesies van die genus Oxalis. In die huidige studie is twee hoofstuifmeeltipes onderskei, naamlik netvormige en verrukate stuifmeeltipes. Die netvormige stuifmeeltipe is verder verdeel in 11 subtipes. Van die 11 subtipes wat onderskei is, kom nege tipes ook in die Suid Afrikaanse taksa van Oxalis voor, terwyl twee stuifmeeltipes slegs by die Amerikaanse soorte van Oxalis voorkom. Die verrukate stuifmeeltipe is slegs in 'n enkele Amerikaanse spesie gevind. Hierdie tipe toon 'n meer komplekse eksienstruktuur as die netvormige stuifmeeltipe. In die huidige studie het die netvormige stuifmeeltipe gebleik die mees algemene stuifmeeltipe in die Amerikaanse Oxalis-spesies te wees. Die Suid Afrikaanse taksa van Oxalis toon meer komplekse stuifmeeltipes as die Amerikaanse taksa.

Thesis (DPhil)--Stellenbosch University, 2002. / ENGLISH ABSTRACT: A biosytematic revision of the seven minor genera of the Hyacinthaceae, including twenty-two species, was undertaken. Muller-Doblies & Muller-Doblies (1997) considered these seven genera (Amphisiphon Barker, Androsiphon Schltr., Daubenya Lindl., Massonia Thunb. ex Houtt., Neobakeria SChItL, Polyxena Kunth and Whiteheadia Harv.) together with the genus Eucomis L'Herit. to form the subtribe Massoniinae of the tribe Massonieae. Previous revisions of the group were based only on morphological characters (Jessop 1976; Muller-Doblies & Muller-Doblies 1997). The subtribe Massoniinae is characterised by the large variety of floral forms exhibited by the different species in the group. In the past this has led to the establishment of many monotypic genera for species thought to have unique floral structures. Morphological, leaf anatomical, palynological, geographical and molecular data were studied in order to delimit the taxa and determine the phylogenetic relationships within the group. This showed that most of the unique floral structures are probably only adaptations to pollination strategies and all except one of the monotypic genera are now placed in the genus Daubenya. In the genus Massonia there is a great deal of variation in leaf morphology and this resulted in the establishment of many invalid species, now mostly reduced to synonymy. A new species was described, several name changes made and several species were reduced to synonymy. / AFRIKAANSE OPSOMMING: 'n Biosistematiese hersiening van die sewe kleiner genera van die Hyacinthaceae, insluitende twee-en-twintig spesies, is onderneem. Muller-Doblies & Muller-Doblies (1997) sluit hierdie sewe genera (Amphisphon Barker, Androsiphon Schltr., Daubenya Lindl., Massonia Thunb. ex Houtt., Neobakeria Schltr., Polyxena Kunth and Whiteheadia Harv.) saam met die genus Eucomis L'Herit. in die subtribus Massoniinae van die tribus Massonieae in. Vorige hersienings van die groep was meestal net op morfologiese kenmerke gebaseer (Jessop 1976; Muller-Doblies & Muller-Doblies 1997). Die subtribus Massoniinae word gekenmerk deur die groot variasie in blomstrukture wat by die verskillende spesies in die groep voorkom. In die verlede het dit gelei tot die beskrywing van verskeie monotipiese genera gegrond op wat geblyk het, unieke blomstrukture te wees. Morfologiese, blaar anatomiese, palinologiese, geografiese en molekulere data is bestudeer om die verskillende taksons af te baken en terselfdertyd die filogenetiese verwantskappe binne die groep te bepaal. Dit het aangetoon dat die unieke blomkenmerke eerder aanpassings aan bestuiwings-strategiee is en dat al hierdie monotipiese genera, behalwe een tot die genus Daubenya behoort. In die genus Massonia is daar baie variasie in blaarmorfologie en dit het veroorsaak dat 'n groot aantal spesies beskryf is, waarvan baie nou as sinonieme beskou word. Een nuwe spesies is beskryf, verskeie naarnsveranderinge is gemaak, en 'n aantal van die spesies is tot sinonieme verander.

Thesis (PhD) -- Stellenbosch University, 1991. / ENGLISH ABSTRACT: The effect of partial defoliation as canopy management practice on metabolism and grape composition of the grapevine, Vitis vinifera L cv. Cabernet Sauvignon, was investigated. The establishment of physiologically sound principles on how to overcome deleterious effects associated with vigorous and dense-canopy vines is emphasized. Experimental vines were defoliated 33 % and 66 % evenly over the whole canopy from different developmental stages in a field study. Effects on canopy microclimate, photosynthesis, photosynthate translocation, vegetative growth, reproductive growth, root development and distribution, as well as grape and wine quality, were determined. A method for the simultaneous extraction of sugars and organic acids from freeze-dried berries at different developmental stages is described. Partial defoliation of vines improved canopy microclimate and photosynthetic efficiency of remaining leaves. Normal translocation and distribution patterns of photosynthates were apparently unaffected by partial defoliation. Translocation to and accumulation of photosynthetic products in the leaves and bunches of partially defoliated vines were, however, improved. Remaining leaves of partially defoliated vines were in comparison photosynthetically more active. Apart from a less favourable canopy microclimate, it seemed that the sink capacity of non-defoliated vines did not comply to the source capacity, inducing a reduced rate of photosynthesis. Normal sigmoidal growth patterns of vines were not affected by partial defoliation as applied in this study. This is important for the longevity, healthiness and productivity of vines. Vegetative growth was differentially affected by partial defoliation. No compensatory leaf growth occurred in reaction to partial defoliation from different developmental stages. Main shoot length, however, decreased slightly. Lateral shoot length and number of laterals increased, whereas cane mass decreased when vines were partially defoliated, particularly the earlier and more severe the defoliation. Reproductive growth in terms of yield was deleteriously affected by 33 % defoliation prior to pea size and 66 % defoliation prior to veraison. Budding percentage was, however, improved by 33 % and 66 % defoliation, whereas bud fertility was only improved by 33 % defoliation. Partial defoliation changed the canopy microclimate to conditions favourable for pest and disease control and higher grape quality. Subterranean growth was favourably affected by partial defoliation, particularly when applied from pea size stage. These changes included higher root densities, development of higher numbers of fine and medium diameter roots and occurrence of higher total root numbers in all soil layers. Generally, defoliations from pea size and veraison were more efficient regarding root development than defoliations from just after bud break and from berry set. Partially defoliated vines reacted by forming new roots, creating a more efficient nutrient absorption capacity and utilization of soil and available water and that, together with higher photosynthetic activities of leaves, provided an efficient mechanism for continued high performance. Grape quality was not affected markedly by partial defoliation. Total soluble solids in berries of defoliated vines were comparable to and even significantly higher than those of non-defoliated vines in some cases, in spite of much lower leaf areas. Generally, total titratable acidity of musts was also slightly higher for partially defoliated vines. Glucose and fructose concentrations in berries were unaffected by partial defoliation, while tartaric acid concentrations were slightly increased and malic acid concentrations slightly decreased. Partial defoliation generally increased the anthocyanin concentration of berry skins. These changes in grape composition suggest higher grape quality and seemed to result from improved light conditions in the canopy interior. Berry volume decreased with partial defoliation, which lowered the pulp:skin ratio. These berries are more desirable for quality wines. Regardless of severity or the developmental stage defoliation was commenced, wine cultivar character and overall wine quality were significantly improved. Partial defoliation changed the general metabolism of vines, mainly in terms of more favourable source:sink ratios, resulting in more efficient photosynthesis, subterranean performance and canopy microclimate. In general, the results suggest that an even removal of 33 % of leaves opposite and below bunches during the period from flowering or berry set to pea size stage may be applied. lt is further suggested that existing vigorous and dense-canopy vines be 33 % defoliated evenly on the lower half of the shoot (canopy) from pea size or veraison. This hypothesis proved effective in improving canopy microclimate, photosynthetic activity and yield, while vegetative growth was inhibited. Grape and wine quality were higher. On the whole, partial defoliation as applied in this study, is recommended as canopy management practice in order to facilitate the abolishment of deleterious effects of excessive vegetative growth and canopy density on balanced metabolic activity, fruit and wine quantity and quality, as well as longevity and healthiness of grapevines. / AFRIKAANSE OPSOMMING: Die invloed van blaarverwydering as loofbestuurspraktyk op die metabolisme en druifsamestelling van die wingerdstok, Vitis vinifera L cv. Cabernet Sauvignon, is ondersoek. Die vestiging van fisiologies-betroubare beginsels oor hoe nadelige effekte geassosieerd met geil en lower-verdigte wingerde uitgeskakel kan word, word beklemtoon. Proefstokke is in 'n veldondersoek 33 % en 66 % eweredig oor die hele lower vanaf verskillende ontwikkelingstadiums ontblaar. Effekte op lowermikroklimaat, fotosintese, translokasie van fotosintetiese produkte, vegetatiewe groei, reproduktiewe groei, wortelontwikkeling en verspreiding asook druif- en wynkwaliteit is bepaal. 'n Metode vir die gelyktydige ekstraksie van suikers en organiese sure uit gevriesdroogde korrels op verskillende groeistadiums is ontwikkel. Blaarverwydering het lowermikroklimaat verbeter en fotosintetiese doeltreffendheid van oorblywende blare op die stok verhoog. Normale translokasie en verspreidingspatrone van produkte van fotosintese is skynbaar nie deur blaarverwydering befiwloed nie. Translokasie na, en akkumulering van fotosintetiese produkte in die blare en druiwe van gedeeltelik ontblaarde stokke, is egter verbeter. Oorblywende blare van gedeeltelik ontblaarde stokke was fotosinteties meer aktief. Afgesien van 'n ongunstiger lowermikroklimaat, het die sinkkapasiteit van nie-ontblaarde stokke skynbaar ook nie teen die bronkapasiteit opgeweeg nie en is 'n verlaagde tempo van fotosintese verkry. Normale sigmofdale groeipatrone van die stokke is nie deur blaarverwydering befrivloed nie. Dit is belangrik vir langlewendheid, gesondheid en produktiwiteit van stokke. Vegetatiewe groei is differensieel deur blaarverwydering befrivloed. Geen kompenserende blaargroei het in reaksie op blaarverwydering vanaf verskillende ontwikkelingstadiums voorgekom nie. Hooflootlengte was egter effens korter. Sylootlengte en aantal sylote het toegeneem, terwyl lootmassa afgeneem het met blaarverwydering, veral hoe vroeer en strawwer dit toegepas is. Reproduktiewe groei in terme van opbrengs is nadelig befrivloed deur 33 % ontblaring voor ertjiekorrelstadium en 66 % ontblaring voor die deurslaanstadium. Botpersentasie is egter deur blaarverwydering verbeter, terwyl oogvrugbaarheid slegs deur 33 % ontblaring verbeter is. Blaarverwydering het 'n gunstige lowermikroklimaat vir die beheer van plae en siektes en hoer druifkwaliteit geskep. Ondergrondse groei is gunstig deur blaarverwydering befrivloed, veral wanneer toegepas vanaf ertjiekorrelstadium. Hierdie veranderinge het ingesluit hoer worteldigtheid, ontwikkeling van groter hoeveelhede wortels met 'n fyn en medium deursnit en die voorkoms van 'n groter aantal totale wortels in alle grondlae. Blaarverwydering vanaf ertjiekorrel- en deurslaanstadia was in die algemeen meer doeltreffend ten opsigte van wortelontwikkeling as blaarverwydering vanaf net na bot en vanaf korrelset. Gedeeltelik ontblaarde stokke het gereageer deur nuwe wortels te vorm, waardeur 'n meer doeltreffende vermoe tot voedingstofopname en benutting van grand an beskikbare water verkry is. Tesame met hoer fotosintetiese aktiwiteite van die blare is 'n doeltreffende meganisme vir aanhoudende hoe prestasie verkry. Druifkwaliteit is nie aanmerklik deur blaarverwydering beirwloed nie. Totale oplosbare stowwe in druiwe van gedeeltelik ontblaarde stokke was vergelykbaar en selfs betekenisvol hoer as die van nie-ontblaarde stokke in sekere gevalle, ten spyte van die baie laer blaaroppervlakte. In die algemeen was die totale titreerbare suur in die mos van gedeeltelik ontblaarde stokke oak effens hoer. Glukose- en fruktosekonsentrasies in die druiwe is nie deur blaarverwydering beinvloed nie. Die konsentrasie wynsteensuur is egter effens verhoog en die appelsuurkonsentrasie effens verlaag. Antosianienkonsentrasie van korreldoppe is in die algemeen deur blaarverwydering verhoog. Hierdie veranderinge in druifsamestelling dui op hoer druifkwaliteit en is skynbaar die resultaat van verbeterde ligtoestande in die binnekant van die lower. Korrelvolume het afgeneem met blaarverwydering. Dit het die pulp:dop verhouding verlaag. Sulke korrels is meer gewens vir bereiding van kwaliteitswyne. Wyn cultivarkarakter en totale wynkwaliteit is betekenisvol deur blaarverwydering verhoog, onafhanklik van die strafheid of ontwikkelingstadium waarvandaan blare verwyder is. Blaarverwydering het die algemene metabolisme van die wingerdstok verander, hoofsaaklik ten opsigte van meer gunstige bron:sink-verhoudings en derhalwe meer doeltreffende fotosintese, ondergrondse groei en lowermikroklimaat. Die resultate dui in die algemeen daarop dat 'n eweredige blaarverwydering van 33 % regoor en onderkant die trosse tydens blomvorming of korrelset tot ertjiekorrelstadium toegepas kan word. Die resultate dui verder daarop dat 33 %van bestaande geil en lower-verdigte stokke se blare eweredig verwyder kan word op die onderste helfte van die loot (lower) vanaf ertjiekorrel- of deurslaanstadium. Hierdie hipotese was suksesvol in die verbetering van lowermikroklimaat, fotosintetiese aktiwiteit en oesmassa. Vegetatiewe groei is gestrem. Druif- en wynkwaliteit was hoer. In die geheel kan blaarverwydering soos toegepas in hierdie ondersoek aanbeveel word as loofbestuurspraktyk ten einde die uitskakeling van nadelige effekte van oormatige vegetatiewe groei en lowerdigtheid op gebalanseerde metaboliese aktiwiteit, druif- en wynkwantiteit en kwaliteit, asook langlewendheid en gesondheid van wingerdstokke te bevorder.

Thesis (MSc (Botany and Zoology))--Stellenbosch University, 2008. / Sequence data from the Internal Transcribed Spacer (ITS) of the nuclear ribosomal DNA were used to study the phylogenetic relationships in the genus Ursinia Gaertn. (Asteraceae, Anthemideae) in the southern African region. Closely related genera, i.e. Cotula L., Osteospermum L. and Agoseris Raf., were used as outgroups. The study also included maximum parsimony and principal component analyses. The taxa within the genus Ursinia had previously been classified into two subgenera, Ursinia and Sphenogyne R.Br., mainly on the basis of distinct cypsela characters. The maximum parsimony, principal component and the phylogenetic analyses revealed two subgenera, corresponding to the existing subgeneric classification. Principal component analysis shows that the pappus, the number of pappus bristles and the colour of the cypsela are the most informative characters. However, the low number of phylogenetically informative characters of the ITS sequences, the poor resolution in the consensus tree, and low branch support values indicate that the ITS data contain weak phylogenetic signals. The low bootstrap values for many nodes suggest that one should be cautious in using the ITS region alone to make final conclusions about the origin and evolution of taxa. In maximum parsimony analysis, the RI, CI and bootstrap values are low; principal component analysis values are also low. Furthermore, there is a lack of resolution in subgenus Sphenogyne. In the literature, Ursinia is divided into seven series but they were not retrieved as monophyletic in this study, probably because of short branch lengths in the phylogeny. Further molecular data are therefore required to be able to support or reject the present classification. Maximum parsimony, principal component and molecular analyses show that U. trifida f. calva Prassler and U. trifida (Thunb.) N.E.Br. f. trifida are not sister taxa, supporting the recognition of these two taxa as separate species. The Ursinia taxa from the summer-rainfall region are not monophyletic and are sister to a clade of Cape species. This supports a hypothesis that Ursinia migrated from the Cape into the Drakensberg which has been shown for a number of other Cape groups that have Drakensberg relatives.

Thesis (MSc)--University of Stellenbosch, 2005. / ENGLISH ABSTRACT: The aim of this study was to elucidate the control of flowering in Protea spp. The main factor that makes studying flowering in this diverse genus so challenging is the fact that most Protea spp. and their commercial hybrids have very dissimilar flowering times. The carbon input into floral organ formation and support is expensive as flowers from Protea spp are arranged in a very large ‘flowerhead’ (50 mm by 130 mm for ‘Carnival’) that can take up to two months to develop fully. Therefore the carbon needed for structural formation, metabolic respiration and the sugar-rich nectar production make these structures extremely expensive to form and maintain. Protea is a sclerophyllous, woody perennial shrub with a seasonal flush growth habit. The leathery leaves (source tissue) produce most of the carbon needed for support and growth of the new leaves, roots and flowers (sink tissue). In the case of expensive structures, such as the inflorescences, remobilization from stored reserves, probably from underground storage systems, can be observed for structural development and maintenance. At all times the flush subtending the apical meristem or florally developing bud provides the largest proportion of carbon for support of the heterotrophic structures. Protea apical meristems stay dormant during the winter months, but BA (benzyl adenine, 6-benzylaminopurine) application to the apical meristem of the Protea hybrid ‘Carnival’ has shown to be effective in the release of dormancy and subsequently shift flowering two months earlier than the natural harvesting time. BA is thought to shift source/sink relationships by stimulating the remobilization of carbon to the resting meristem. Although no direct evidence was found for this in our assay, possible reasons for a weak assay are discussed. This study combined physiological research with the use of molecular tools. An homologue of the Arabidopsis thaliana meristem identity gene, LEAFY, was identified in Proteaceae. PROFL (PROTEA FLORICAULA LEAFY) is expressed in both vegetative and reproductive meristems as well as leaves. PROFL expression in leaves may have an inhibitory effect on vegetative growth, as the expression was high at the same time as the expression in the apical meristem increased marking the transition to reproductive growth. In perennial species such as Protea, the availability of carbon is thought to be the main factor controlling floral development. Possible mechanisms of control may be through the direct control of meristem identity genes such as PROFL through sugar signaling. BA did not have a direct effect on PROFL expression although the expression pattern was one month in advance when compared to the natural system. PROFL expression seems to be consistent with that found for other woody perennial species and would therefore be a convenient marker for floral transition. / AFRIKAANSE OPSOMMING: Die doel van hierdie studie was om die inisiëring van blomvorming in Protea spp. te ondersoek. Die verskil in blomtyd tussen Protea spp. en hul kommersieel ontwikkelde hibriede maak die studie van hierdie genus ‘n groot uitdaging. Die groot hoeveelheid koolstof wat benodig word vir blomvorming in Protea is hoofsaaklik as gevolg van die grootte (50 mm by 130 mm vir ‘Carnival’) van die blomkop waarin individuele blomme geranskik is. Hierdie blomkoppe kan tot 2 maande neem om volwassenheid te bereik. Die koolstof benodig vir strukturele ontwikkeling, metaboliese respirasie en produksie van suiker-ryke nektar maak die vorming van hierdie structure ongelooflik duur. Protea is ‘n bladhoudende, houtagtige bos met ‘n seisoenale groeipatroon. Die leeragtige blare voorsien die grootste hoeveelheid koolstof vir die ontwikkelende blare, wortels en blomme. Koolstof vir die ontwikkeling en ondersteuning van die groot stukture soos die blomkoppe word gedeeltelik deur die huidige fotosinfaat voorsien en bewyse vir die remobilisasie van gestoorde koolstof, heel waarskynlik vanaf ondergrondse stukture, is gevind. Die blare van die stemsegment wat die apikale meristeem of ontwikkelende blom dra, voorsien altyd die grootse hoeveelheid koolhidrate aan die ontwikkelende struktuur. Die apikale meristeme van Protea bly dormant gedurende die winter maande, maar applikasie van BA (bensieladenien, 6-bensielaminopurien) aan die apikale meristeme van die Protea hibried ‘Carnival’ verbreek dormansie en die blomtyd van hierdie gemanipuleerde plante is daarom twee maande vroeër as die natuurlike oestyd. Daar word gespekuleer dat BA applikasie aan die apikale meristeem die hoeveelheid koolstof wat na die dormante meristeem gestuur word verhoog wat dan die dormansie verbreek. Hierdie studie beproef ongelukkig hierdie hipotese swak en redes hiervoor word bespreek. In hierdie studie word fisiologiese analises met molekulêre studies gekombineer. ‘n Meristeem identiteits gene wat homologie wys met LEAFY (LFY) in Arabidopsis thaliana (Arabidopsis), PROFL (PROTEA FLORICAULA LEAFY), is in Proteaceae geïdentifiseer. PROFL word uitgedruk in reproduktiewe meristeme so wel as die vegetatiewe meristeme en blare. PROFL uitdrukking in blare mag dalk ‘n inhiberende effek hê op die vorming van nuwe blare, omdat die uitdrukking hoog was op die selfde tyd as wat blominisiëring plaasgevind het in die apikale meristeem. Die transisie tot reproduktiewe groei word gekenmerk deur ‘n verhoging in PROFL uitdrukking in die apikale meristeem. In meerjarige plante soos Protea spp word daar verwag dat die teenwoordigheid van voldoende koolstof die oorskakeling na reproduktiewe groei inisieer. Dit mag wees deur die direkte aksie van suikers met gene soos PROFL wat die finale skakel na reproduktiewe groei beheer. Alhoewel BA applikasie geen direkte effek gehad het op PROFL uitdrukking nie, was die blomtyd met twee maande vervroeg. PROFL uitdrukking was vergelykbaar met die uitdrukking van LFY homoloë in ander houtagtige, meerjarige plante en kan gebruik word as ‘n merker vir blominisiëring in Protea spp.

Thesis (MSc)--University of Stellenbosch, 2000. / ENGLISH ABSTRACT: The changes in carbon allocation to sucrose, hexoses, fibre, starch and respiration were investigated in developing internodes of sugarcane. Radiolabelling studies were conducted on internode 3, 6 and 9 tissue, representing three stages of increasing maturity. It was apparent that a high rate of cycling between triose-phosphate and hexose-phosphate occurred. A maximum of 50% of carbon entering triose-phosphates was returned to hexose-phosphate in internode 3 tissue, and this flux decreased with tissue maturity to 30%. Carbon partitioning into sucrose increased from 34% of total 14C uptake in internode 3, to 61% in internodes 6 and 9. In immature tissue, the protein and fibre components were the dominant competing sinks with sucrose for incoming carbon, to which 14 and 16% of carbon were allocated respectively. Increased carbon allocation to sucrose with tissue maturity, coincided with a decrease in partitioning to fibre. This indicated that previous studies had underestimated total carbon allocation to respiration, since the protein component was not considered. In contrast with earlier work, the respiratory pathway was the strongest competitor with sucrose for incoming carbon, even in mature tissue. Between internodes 3 and 6, carbon allocation to total respiration did not change significantly, but decreased 50% in mature tissue. Starch was a weak competitor with sucrose, for incoming carbon, to which a maximum of 2% of 14Cwas allocated in immature tissue. In cane harvested in early spring, radiolabelled maltose was recovered in internode 3 tissue of ripening cane, indicating that concomitant starch synthesis and degradation occurred. The. redistribution of C-1 and C-6 in starch glucose was analysed following feeding of tissue with [1_14C]_and [6_14C]_glucose. Randomization of label in starch indicated that the pathway for carbon movement into sugarcane plastids for starch synthesis is primarily through the triose-phosphate translocator. Finally, this study indicated that radiolabelling of tissue discs is a suitable experimental system to determine carbon flux in sugarcane. During the 3 h labelling period the rate of 14C02 release became linear, indicating that the system approached isotopic steady state between the external and internal glucose pool; and the respiratory processes involved in CO2 release. / AFRIKAANSE OPSOMMING: Die veranderinge in koolstoftoedeling na sukrose, heksoses, vesel, stysel en respirasie is in ontwikkelende internodes van suikerriet ondersoek. Die koolhidraatmetabolisme in internodes 3, 6 en 9, wat drie stadiums van toenemende rypheid verteenwoordig, is met behulp van 14Cmerkingstudies ondersoek. Dit is duidelik dat daar 'n hoë mate van koolstofsirkulering tussen die heksose- en triose-fosfaat poele voorkom. In internode 3 word tot 50% van die koolstofwat in triose-fosfate geïnkorporeer is, weer na heksosefosfaat omgeskakel. Selfs in volwasse weefsel vind daar nog soveel as 30% koolstofsirkukering plaas tussen die twee poele plaas. Koolstoftoedeling vanaf glukose na sukrose het van 34% in internode 3, tot 61% in internodes 6 en 9 toegeneem. Proteïn en selwandkomponente was die belangrikste swelgpunte vir koolstof in onvolwasse weefsel gewees. Namate die weefsel meer volwasse word, word sukrose 'n belangriker swelgpunt. Die koolstoftoedeling aan sukrose is veral ten koste van toedeling aan die selwandkomponente. Die bevinding dat die proteïenpoel 'n sterk swelgpunt is dui aan dat vorige studies die belang van respiratoriese koolstofvloei onderskat het. In teenstelling met vorige aansprake is dit duidelik dat selfs in volwasse weefsel respirasie die grootste swelpunt vir die inkomende organiese koolstof in die internode vorm. Koolstoftoedeling aan respirasie het nie noemenswaardig tussen internodes 3 en 6 verskil nie, maar het met 50% in volwasse weefsel afgeneem. Stysel is deurgaans 'n swak swelgpunt vir koolstof met die hoogste toedeling aan die poel (2%) in die jong weefsel (internode 3) . Na toediening van [U- 14C]-glukose is radioaktief gemerkte maltose gevind in suikerriet wat vroeg in die lente geoes is. Dit dui aan dat gelyktydige afbraak en sintese van stysel plaasgevind het. Die herverdeling van C-l en C-6 in glukose afkomstig van stysel is na toediening van [1_14C]_ en [6-14C]-glukose ontleed. Die ewekansige verspreiding van radioaktiwiteit tussen koolstof 1 en 6 van die glukose in stysel dui aan dat dit hoofsaaklik die triose-fosfaat translokeerder is wat in die plastied verantwoordelik is. Hierdie studie het ook aangetoon dat radioaktiewe merking van weefselsnitte 'n geskikte eksperimentele sisteem is om koolstoftoedeling in suikerriet te ondersoek. Die patroon van 14C02 vrystelling dui daarop dat die weefsel na 'n 3 h inkuberingsperiode isotopiese ewewig tussen die eksterne en interne glukose poele en die respiratoriese prosesse begin bereik het.

Thesis (MSc)--University of Stellenbosch, 2002. / ENGLISH ABSTRACT: Two key attributes of biodiversity, species richness and endemism are documented, analysed and mapped for the indigenous spermatophyte plant taxa of Namibia. A provisional diversity map is presented and transitional zones were shown to be the most significant for species richness. Distribution maps of the majority of endemic species in Namibia are shown together for the first time. Combinations of these data were used to map the overall distribution of endemic taxa, localities where significant numbers of local endemics occur, as well as the species that can be found in taxon phytogeographic centres. Recurring patterns are evident and areas of high species concentrations are catalogued. This thesis has contributed to the knowledge of the large number of plant taxa for .which Namibia is solely responsible, i.e. endemics restricted to within the political borders of Namibia. The mapping used an updateable, but permanent dataset on which future applications can be based. Examples of the uses of phytogeographic information proposed, include not only the traditional role in the identification of species in the herbarium, but also in creating a better basis for future policy especially in the development of land management strategies and conservation of Namibia's plant wealth / AFRIKAANSE OPSOMMING: Twee sleutelkenmerke van biodiversiteit, naamlik spesiesrykheid en endemisme word dokumenteer, ontleed, en karteer vir die inheemse saadplante van Namibië. 'n Voorlopige kaart van diversiteit word voorsien waaruit blyk dat oorgangsgebiede die belangrikste is vir spesiesrykheid. Verspreidingskaarte van meeste van die endemiese spesies in Namibië is word vir die eerste keer gesamentlik aangebied. Kombinasies van hierdie gegewens is gebruik om die algehele verspreiding van endemiese taksa, plekke waar betekenisvolle aantalle plaaslike endemiese taksa voorkom, sowel as die spesies wat voorkom in takson-geografiese sentrums, te karteer. Herhalende patrone is sigbaar, en gebiede met hoë specieskonsentrasies is gelys. Hierdie tesis het bygedra tot die kennis van 'n groot aantal plantsoorte waarvoor Namibië alleen verantwoordelik is, synde endemiese soorte wat beperk is tot binne die polieke grense van Namibië. Die kartering het 'n opdateerbare, maar permanente, databasis gebruik waarop toekomstige aanwendings baseer kan word. Voorbeelde van die gebruike van plantgeografiese inligting wat voorgestel is, sluit in tradisionele gebruik in die identifikasie van species in die herbarium, sowel as die skepping van 'n beter fondament vir toeskomstige beleid in veral die ontwikkeling van bestuurstrategië en bewaring van Namibia se planterykdom