Thesis (MSc (Genetics))--University of Pretoria, 2005. / Includes summary. Includes bibliographical references. Available on the Internet via the World Wide Web.

Th. univ.--Pharm.--Montpellier 1, 1981.

Thesis (MSc.(Microbiology and Plant Pathology)-University of Pretoria, 2006. / Summary in English and Afrikaans. Includes bibliographical references.

To ensure acceptable survival and initial growth of Eucalyptus grandis clonal and clonal hybrid material planted in the cool temperate and sub-tropical climates of Zululand (KwaZulu-Natal, South Africa) the planting seasons are currently restricted to the winter or summer months respectively. The Zululand coast (sub-tropical climate) experiences traditionally hot and humid summers and as a result Eucalyptus planting is largely restricted to the cool and dry winter months when survival is acceptable (90- 95%). In comparison, the Zululand interior (cool temperate climate) experiences moderately cooler summers followed by drier winters. As a result, the Eucalyptus planting season is reversed to that of the Zululand coast, with most of the planting taking place during the summer months with little or no planting occurring during winter. To ensure adequate transplant survival during and beyond these periods, transplants are planted with large volumes of water at a high cost. To determine whether it was possible to significantly reduce current water volumes at planting and therefore reduce costs, and to potentially extend the current planting seasons, two field trials were initiated during traditionally “unsuitable” planting periods (winter months for the Zululand interior and summer months for the Zululand coast). These trials were established near Kwambonambi on the Zululand coast and at Ntonjaneni in the Zululand interior. Five levels of water were combined with five levels of hydrogel and applied to the pit at planting in a 5 x 5 factorial treatment design for both trials. The tree variates of mortality, height, groundline diameter, crown diameter, corrected leaf surface index (LSIC) and corrected biomass index (BIC) were assessed at regular intervals until the final measurement dates (118 and 128 days after planting for the Ntonjaneni and Kwambonambi trials respectively). For the Kwambonambi trial, the response of transplant survival to the application water was highly significant (p<0,01) 128 days after planting, but not to the application of the hydrogel. Transplant survival nevertheless conformed to the silviculturally accepted norms of 90-95% using the hydrogel, thus water volumes could be significantly reduced without negatively affecting current survival standards. The lack of the expected response of significantly reduced transplant survival to increasing levels of hydrogel could possibly be attributed to the significant rainfall event (146 mm) that fell two days after trial initiation. Increasing levels of both water and hydrogel resulted in significantly enhanced growth (LSIC and BIC: p<0.01) for the final measurement date. For the Ntonjaneni trial, there was a significant (p<0,01) interaction between hydrogel and water, 118 days after planting. There were significant (p<0,01) differences between water only and all hydrogel treatments, with the hydrogel treatments performing significantly better. Optimum transplant survival for water only treatments was 50% using 4000 ml water while that for hydrogel treatments was 100% using 6 g hydrogel with 1000 ml of water and 12 g hydrogel with 2000 ml of water. The variates, corrected leaf surface index and corrected biomass index indicated that tree growth was significantly enhanced by the addition of a hydrogel over all levels of water. A pot trial was subsequently implemented to ascertain whether the significant increases obtained for initial transplant growth for the sandy clay loam soils of Ntonjaneni were due to an initial but unsustainable positive response of the roots to the presence of the hydrogel, or whether root growth was sustainably advantaged by the presence of the hydrogel. There was a highly significant (p<0,01) response of root biomass and above ground biomass over all levels of hydrogel, including a significant positive linear (p<0,01) relationship between increased root biomass and above ground biomass. This clearly indicated that initial root growth was not negatively affected by the addition of the soil-amending hydrogel Stockosorb 400K.

Eucalyptus urophylla is one of the most extensively used forest tree species in plantation forestry worldwide. Commonly, E. urophylla is used in hybrid combinations with species possessing better wood properties largely because it is an exceptional grower and it imparts good disease resistance. E. urophylla is endemic to islands of the Lesser Sunda archipelago situated north of Australia. Human induced deforestation practices including urbanization are threatening the existence of several natural populations of the species throughout its range. It has become crucial that efforts be made to conserve the genetic resources in this species. To this end, a forest tree conservation genetics organization called Camcore (http://www.camcore.org) in collaboration with other forestry institutions has initiated seed collection explorations throughout the Lesser Sunda archipelago. Collected seed was sown in provenance test trials to gather information including growth performance of different genotypes in exotic locations. Comprehensive species-wide genetic diversity surveys (at the gene and genome levels) will assist in determining the genetic relationships between different E. urophylla populations, information that is relevant for guiding in situ and ex situ conservation strategies for the species. Nucleotide diversity studies exploit the diversity between homologous gene sequences from different individuals to identify the genetic variation underlying phenotypic traits. Commonly, genetic variation is in the form of single nucleotide polymorphisms (SNPs). Information on SNP diversity coupled with a detailed understanding of the molecular evolution of candidate genes including linkage disequilibrium (LD), selection and recombination may lead to the identification of haplotypes (a combination of SNPs that are inherited together) that associate with trait variation. Thus, sequence diversity surveys in candidate wood biosynthetic genes in E. urophylla may lead to the identification of allelic (SNP) haplotypes that associate with wood quality traits. Such haplotypes will be very valuable in Eucalyptus breeding programmes. The aim of the current M.Sc. study was to investigate levels of nucleotide and allelic (SNP) diversity in three candidate wood biosynthetic genes of E. urophylla. Levels of nucleotide diversity were surveyed in two cellulose biosynthetic genes, namely, cellulose synthase 1 (CesA1) and sucrose synthase 1 (SuSy1) , and the lignin biosynthetic gene cinnamyl alcohol dehydrogenase 2 (CAD2) of E. urophylla. This was achieved by sequencing two DNA fragments of approximately 1000 base pairs (bp) from the 5’ and 3’ ends of one randomly cloned allele (for each gene) in each of the 25 E. urophylla representative individuals. These individuals originated from different families and populations across the seven islands of the Lesser Sunda archipelago. Average levels of nucleotide diversity () and SNP haplotype diversity in EuCesA1, EuSuSy1 and EuCAD2 genes were approximately 1% and 0.95, respectively. SNP density was similar among the three genes with one SNP occurring every 40 bp on average. LD declined to minimal levels within 1000 bp in EuCesA1 and EuSuSy1, but remained significant across the 3000 bp length of EuCAD2. An allele-based geographic analysis based on SNP haplotypes revealed that there was no significant clustering of SNP haplotypes based on island of origin. Nonetheless, high SNP density and low LD levels suggest that the E. urophylla may be useful for high-resolution LD mapping and gene-based marker development for marker-assisted breeding programmes. / Dissertation (MSc)--University of Pretoria, 2009. / Genetics / unrestricted

Thesis (M.Sc.)(Microbiology)--University of Pretoria, 2005. / Title from opening screen (viewed March 28, 2006). Includes summary. Includes bibliographical references.

Approved for entry into archive by Patricia Barros (patricia.barros@ufes.br) on 2016-06-23T18:04:37Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Propriedades da madeira de eucalipto para a produção de madeira serrada.pdf: 1213256 bytes, checksum: a3a6beecc882902f8572185da646cf88 (MD5) / Made available in DSpace on 2016-06-23T18:04:38Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Propriedades da madeira de eucalipto para a produção de madeira serrada.pdf: 1213256 bytes, checksum: a3a6beecc882902f8572185da646cf88 (MD5) / O objetivo do trabalho foi mensurar as deformações residuais longitudinais (DRL) decorrentes das tensões de crescimento em árvores de 20 de clones de Eucalyptus grandis x Eucalyptus urophylla com 13 anos de idade. Foram medidas o tamanho da copa, o diâmetro à altura do peito (DAP) e a espessura da casca. As medições das DRL nas posições norte e sul do fuste foram realizadas de acordo com o método do CIRAD-Forêt. Houve diferença significativa entre clones para DAP, DRL e espessura de casca. Não houve correlação significativa entre DAP e DRL. A correlação foi significativa entre DAP e tamanho da copa, podendo-se afirmar que o tamanho da copa afeta o crescimento diamétrico das árvores. DAP e espessura de casca também se correlacionaram significativamente, em que árvores de maiores diâmetros possuem cascas mais espessas. Foi possível selecionar clones com melhor potencial para produção de madeira serrada, isto é, elevados DAP com reduzidas DRL. / This study aims to evaluate growth stress measuring the longitudinal growth strain (LGS) of randomly selected trees from different clones of Eucalyptus grandis x Eucalyptus urophylla hybrid. Twenty 13-year-old clones, from Alcobaça, Bahia state, Brazil. Visual analysis of the crown size, diameter at breast height (DBH) and bark thickness were measured. LGS in the North and South positions the stem were made with the aid of the extensometer, called Growth Strain Gauge method, by CIRAD-Forêt. Significant differences were found between clones for DBH, LGS and bark thickness. There was no significant correlation between DBH and LGS. The correlation was significant between DBH and crown size. It can be stated that the size of the crown affects the diameter of the trunk of trees. The correlation was also significant between DBH and bark thickness, larger DBH trees have thicker bark. It was possible to select clones with better potential for lumber production, i.e. higher DBH with reduced LGS.

In clonal deployment programmes of plantation species, there is frequently the need to deploy Eucalyptus species and interspecific hybrids as rooted cuttings. However, the rooting ability of a particular species or hybrid is a major, and usually limiting, factor affecting the economics of commercial deployment. There is also significant between-species and between-family variation for this trait. Recently, Eucalyptus longirostrata was crossed with E. grandis in an effort to combine its desirable wood properties, drought tolerance and disease resistance with the latter's vigorous growth. Should progeny with these suitable characteristics be identified, there is the possibility of extending plantations to more marginal areas and increasing the quality and volume from existing plantations. An investigation was undertaken to study the rooting ability of E. grandis x E. longirostrata hybrid cuttings. The plant material was sourced from five families in seedling derived hedges at two nurseries, as well as five families coppiced from an unreplicated progeny trial planted in the midlands of KwaZulu-Natal. Their rooting ability was assessed by determining the percentage of cuttings that developed roots using two different rooting methods. The variation between and within families and clones is presented. The study shows that root strike is under moderate genetic control, with an estimate of broad-sense rooting heritability of 0.197 (S.E. = 0.070). The two nurseries used in this study used different rooting technologies, with cuttings rooted either in media (traditional method) or in air (aeroponically). The aeroponics technology was highly significantly (p<0.0001) superior, in terms of rooting success. Rooting was also highly significantly affected (p<0.0001) by the temperature at the time of cutting. Rooting success of cuttings from seedling-derived parental hedges was similar to cuttings from coppiced stumps. The consequences of the low repeatability of measurements of rooting ability, 0.187 (S.E. 0.067) by clone and 0.340 (S.E. 0.072) by ramet, which was influenced by the response to age of material and nursery conditions, is discussed. This study demonstrated that large improvements in rooting success can be made by the optimization of rooting protocols and selecting for superior genotypes, as long as the performances of genotypes are accurately assessed. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2011.

O Brasil é um dos maiores produtores de polpa de eucalipto e suas plantações são dependentes do enraizamento adventício de genótipos selecionados. Neste trabalho foram analisados os efeitos de diferentes fontes de carboidratos e de qualidade de luz no enraizamento adventício in vitro de duas espécies de eucalipto economicamente importantes, Eucalyptus grandis, de fácil enraizamento e Eucalyptus globulus, recalcitrante ao enraizamento. As fontes de carboidratos testadas em meio de cultura líquido foram sacarose, glicose e frutose. Microestacas de ambas as espécies e plantas-matrizes de Eucalyptus globulus foram expostas a comprimentos de onda enriquecidos para luz branca, azul, vermelha e vermelho-extrema e seus efeitos foram testados em relação ao enraizamento. O enraizamento adventício aumentou em ambas as espécies quando foi fornecida sacarose durante a fase de indução e frutose na fase de formação. Fazendo uma analogia entre o enraizamento adventício e a tuberização de batata, este resultado pode ser atribuído a atividade de invertases na fase de indução e fructoquinase na fase de formação, porém mais estudos devem ser conduzidos para confirmar esta hipótese. Não houve efeito de qualidade de luz no enraizamento adventício quando os tratamentos de luz foram aplicados nas microestacas. A exposição de plantas-matrizes crescidas em meio de cultura sem sacarose à ambiente enriquecido com comprimento de onda vermelho-extremo proporcionou um aumento de 255% na porcentagem de enraizamento de suas microestacas, mesmo na ausência de auxina exógena no meio de enraizamento, quando comparado com plantas-matrizes expostas à luz branca nas mesmas condições de cultura. Este resultado está aparentemente relacionado com o balanço 8 endógeno de açúcares solúveis e amido na parte aérea e raízes em desenvolvimento, com maior conteúdo de ambos na região das raízes. / Brazil is one of the largest producers of eucalypt pulp and its plantations are dependent of adventitious rooting of selected genotypes. In this work we analyzed the effects of different carbohydrate sources and light qualities on in vitro adventitious rooting of two economically important eucalypt species, the easy-to-root Eucalyptus grandis and the recalcitrant Eucalyptus globulus. The carbohydrate sources tested in static liquid medium were sucrose, glucose and fructose. The effect of white, blue, red and far-red light exposure on microcuttings of both species and on donor-plants of E. globulus was evaluated in relation to rooting. Rooting was improved in both species by supplying sucrose in the induction phase and fructose in the formation phase. By a putative analogy of adventitious rooting with tuberization in potato stems, this result was attributed to activities of invertases in the induction phase and fructokinase in the formation phase, but more studies will be needed to confirm this hypothesis. There was no effect of light quality on adventitious rooting when light treatments were applied on microcuttings. Compared to the white light-treated control donor-plants grown on medium without sucrose, donor-plants grown under a far-red light enriched environment on medium devoid of sucrose yielded 255% in the rooting percentage of microcuttings derived therefrom, even in the absence of exogenous auxin in rooting medium. This result was apparently related to the balance between endogenous hexoses and starch content in shoots and developing roots, with a higher content of both in the rooting zone.

Box-Ironbark forests occur on the inland hills of the Great Dividing Range in Australia, from western Victoria to southern Queensland. These dry, open forests are characteristically dominated by Eucalyptus species such as Red Ironbark E. tricarpa, Mugga Ironbark E. sideroxylon and Grey Box E. microcarpa. Within these forests, several Eucalyptus species are a major source of nectar for the blossom-feeding birds and marsupials that form a distinctive component of the fauna. In Victoria, approximately 83% of the original pre - European forests of the Box-Ironbark region have been cleared, and the remaining fragmented forests have been heavily exploited for gold and timber. This exploitation has lead to a change in the structure of these forests, from one dominated by large 80-100 cm diameter, widely -spaced trees to mostly small (≥40 cm DBH), more densely - spaced trees. This thesis examines the flowering ecology of seven Eucalyptus species within a Box-Ironbark community. These species are characteristic of Victorian Box-Ironbark forests; River Red Gum E. camaldulensis, Yellow Gum E. leucoxylon, Red Stringybark E. macrorhyncha, Yellow Box E. melliodora, Grey Box E. microcarpa, Red Box E. polyanthemos and Red Ironbark E. tricarpa. Specifically, the topics examined in this thesis are: (1) the floral character traits of species, and the extent to which these traits can be associated with syndromes of bird or insect pollination; (2) the timing, frequency, duration, intensity, and synchrony of flowering of populations and individual trees; (3) the factors that may explain variation in flowering patterns of individual trees through examination of the relationships between flowering and tree-specific factors of individually marked trees; (4) the influence of tree size on the flowering patterns of individually marked trees, and (5) the spatial and temporal distribution of the floral resources of a dominant species, E. tricarpa. The results are discussed in relation to the evolutionary processes that may have lead to the flowering patterns, and the likely effects of these flowering patterns on blossom-feeding fauna of the Box-Ironbark region. Flowering observations were made for approximately 100 individually marked trees for each species (a total of 754 trees). The flower cover of each tree was assessed at a mean interval of 22 (+ 0.6) days for three years; 1997, 1998 and 1999. The seven species of eucalypt each had characteristic flowering seasons, the timing of which was similar each year. In particular, the timing of peak flowering intensity was consistent between years. Other spatial and temporal aspects of flowering patterns for each species, including the percentage of trees that flowered, frequency of flowering, intensity of flowering and duration of flowering, displayed significant variation between years, between forest stands (sites) and between individual trees within sites. All seven species displayed similar trends in flowering phenology over the study, such that 1997 was a relatively 'poor' flowering year, 1998 a 'good' year and 1999 an 'average' year in this study area. The floral character traits and flowering seasons of the seven Eucalyptus species suggest that each species has traits that can be broadly associated with particular pollinator types. Differences between species in floral traits were most apparent between 'summer' and 'winter' flowering species. Winter - flowering species displayed pollination syndromes associated with bird pollination and summer -flowering species displayed syndromes more associated with insect pollination. Winter - flowering E. tricarpa and E. leucoxylon flowers, for example, were significantly larger, and contained significantly greater volumes of nectar, than those of the summer flowering species, such as E. camaldulensis and E. melliodom. An examination of environmental and tree-specific factors was undertaken to investigate relationships between flowering patterns of individually marked trees of E. microcarpa and E. tricarpa and a range of measures that may influence the observed patterns. A positive association with tree-size was the most consistent explanatory variable for variation between trees in the frequency and intensity of flowering. Competition from near-neighbours, tree health and the number of shrubs within the canopy area were also explanatory variables. The relationship between tree size and flowering phenology was further examined by using the marked trees of all seven species, selected to represent five size-classes. Larger trees (≥40 cm DBH) flowered more frequently, more intensely, and for a greater duration than smaller trees. Larger trees provide more abundant floral resources than smaller trees because they have more flowers per unit area of canopy, they have larger canopies in which more flowers can be supported, and they provide a greater abundance of floral resources over the duration of the flowering season. Heterogeneity in the distribution of floral resources was further highlighted by the study of flowering patterns of E. tricarpa at several spatial and temporal scales. A total of approximately 5,500 trees of different size classes were sampled for flower cover along transects in major forest blocks at each of five sample dates. The abundance of flowers varied between forest blocks, between transects and among tree size - classes. Nectar volumes in flowers of E. tricarpa were sampled. The volume of nectar varied significantly among flowers, between trees, and between forest stands. Mean nectar volume per flower was similar on each sample date. The study of large numbers of individual trees for each of seven species was useful in obtaining quantitative data on flowering patterns of species' populations and individual trees. The timing of flowering for a species is likely to be a result of evolutionary selective forces tempered by environmental conditions. The seven species' populations showed a similar pattern in the frequency and intensity of flowering between years (e.g. 1998 was a 'good' year for most species) suggesting that there is some underlying environmental influence acting on these aspects of flowering. For individual trees, the timing of flowering may be influenced by tree-specific factors that affect the ability of each tree to access soil moisture and nutrients. In turn, local weather patterns, edaphic and biotic associations are likely to influence the available soil moisture. The relationships between the timing of flowering and environmental conditions are likely to be complex. There was no evidence that competition for pollinators has a strong selective influence on the timing of flowering. However, as there is year-round flowering in this community, particular types of pollinators may be differentiated along a temporal gradient (e.g. insects in summer, birds in winter). This type of differentiation may have resulted in the co-evolution of floral traits and pollinator types, with flowers displaying adaptations that match the morphologies and energy requirements of the most abundant pollinators in any particular season. Spatial variation in flowering patterns was evident at several levels. This is likely to occur because of variation in climate, weather patterns, soil types, degrees of disturbance and biotic associations, which vary across the Box-Ironbark region. There was no consistency among sites between years in flowering patterns suggesting that factors affecting flowering at this level are complex. Blossom-feeding animals are confronted with a highly spatially and temporally patchy resource. This patchiness has been increased with human exploitation of these forests leading to a much greater abundance of small trees and fewer large trees. Blossom-feeding birds are likely to respond to this variation in different ways, depending upon diet-breadth, mobility and morphological and behavioural characteristics. Future conservation of the blossom-feeding fauna of Box-Ironbark forests would benefit from the retention of a greater number of large trees, the protection and enhancement of existing remnants, and revegetation with key species, such as E. leucoxylon, E. microcarpa and E. tricarpa. The selective clearing of summer flowering species, which occur on the more fertile areas, may have negatively affected the year-round abundance and distribution of floral resources. The unpredictability of the spatial distribution of flowering patches within the region means that all remnants are likely to be important foraging areas in some years.